SFU-style fifo is empty file with system attribute set. This format is used
by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
(which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
SFU-style socket is file which has system attribute set and file content is
one zero byte. This format was introduced in Interix 3.0 subsystem, as part
of the Microsoft SFU 3.0 and is used also by all later versions. Previous
versions had no UNIX domain socket support.
Currently when sfu mount option is specified then CIFS creates fifo and
socket special files with some strange LnxSOCK or LnxFIFO content which is
not compatible with Microsoft SFU and neither recognized by other SMB
implementations which have some SFU support, including older Linux cifs
implementations.
So when sfu mount option is specified, create all fifo and socket special
files compatible with SFU format to achieve SFU interop, as it is expected
by sfu mount option.
Signed-off-by: Pali Rohár <pali@kernel.org>
---
fs/smb/client/cifssmb.c | 8 ++++----
fs/smb/client/smb1ops.c | 2 +-
fs/smb/client/smb2ops.c | 29 +++++++++++++++++++----------
3 files changed, 24 insertions(+), 15 deletions(-)
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index cfae2e918209..0ffc45aa5e2c 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
- /* set file as system file if special file such
- as fifo and server expecting SFU style and
+ /* set file as system file if special file such as fifo,
+ * socket, char or block and server expecting SFU style and
no Unix extensions */
if (create_options & CREATE_OPTION_SPECIAL)
@@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
req->AllocationSize = 0;
/*
- * Set file as system file if special file such as fifo and server
- * expecting SFU style and no Unix extensions.
+ * Set file as system file if special file such as fifo, socket, char
+ * or block and server expecting SFU style and no Unix extensions.
*/
if (create_options & CREATE_OPTION_SPECIAL)
req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
index e1f2feb56f45..e03c91a49650 100644
--- a/fs/smb/client/smb1ops.c
+++ b/fs/smb/client/smb1ops.c
@@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
/*
* Check if mounted with mount parm 'sfu' mount parm.
* SFU emulation should work with all servers, but only
- * supports block and char device (no socket & fifo),
+ * supports block and char device, socket & fifo,
* and was used by default in earlier versions of Windows
*/
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 9c2d065d3cc4..9e90672caf60 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -5066,26 +5066,32 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
struct cifs_fid fid;
unsigned int bytes_written;
struct win_dev pdev = {};
+ size_t pdev_len = 0;
struct kvec iov[2];
__u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
int rc;
switch (mode & S_IFMT) {
case S_IFCHR:
+ pdev_len = sizeof(pdev);
memcpy(pdev.type, "IntxCHR\0", 8);
pdev.major = cpu_to_le64(MAJOR(dev));
pdev.minor = cpu_to_le64(MINOR(dev));
break;
case S_IFBLK:
+ pdev_len = sizeof(pdev);
memcpy(pdev.type, "IntxBLK\0", 8);
pdev.major = cpu_to_le64(MAJOR(dev));
pdev.minor = cpu_to_le64(MINOR(dev));
break;
case S_IFSOCK:
- strscpy(pdev.type, "LnxSOCK");
+ /* SFU socket is system file with one zero byte */
+ pdev_len = 1;
+ pdev.type[0] = '\0';
break;
case S_IFIFO:
- strscpy(pdev.type, "LnxFIFO");
+ /* SFU fifo is system file which is empty */
+ pdev_len = 0;
break;
default:
return -EPERM;
@@ -5100,14 +5106,17 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
if (rc)
return rc;
- io_parms.pid = current->tgid;
- io_parms.tcon = tcon;
- io_parms.length = sizeof(pdev);
- iov[1].iov_base = &pdev;
- iov[1].iov_len = sizeof(pdev);
+ if (pdev_len > 0) {
+ io_parms.pid = current->tgid;
+ io_parms.tcon = tcon;
+ io_parms.length = pdev_len;
+ iov[1].iov_base = &pdev;
+ iov[1].iov_len = pdev_len;
+
+ rc = server->ops->sync_write(xid, &fid, &io_parms,
+ &bytes_written, iov, 1);
+ }
- rc = server->ops->sync_write(xid, &fid, &io_parms,
- &bytes_written, iov, 1);
server->ops->close(xid, tcon, &fid);
return rc;
}
@@ -5149,7 +5158,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
/*
* Check if mounted with mount parm 'sfu' mount parm.
* SFU emulation should work with all servers, but only
- * supports block and char device (no socket & fifo),
+ * supports block and char device, socket & fifo,
* and was used by default in earlier versions of Windows
*/
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
--
2.20.1
Per Steve's request I'm re-sending changes from PATCH 6/7 and PATCH 7/7 from patch series "cifs: Improve client SFU support for special files" (Sep 12, 2024). There is no functional change, just split and reorder. All changes are: * Use ARRAY_SIZE() instead of magic value 2 * Patch for SFU symlinks (original 6/7) is the first one * Patch for SFU fifo/sockets is after symlinks and is split into other tree independent patches (socket, fifo and comments), so every one can be applied separatetely or dropped if would not be acceptable. Pali Rohár (4): cifs: Add support for creating SFU symlinks cifs: Fix creating of SFU socket special files cifs: Fix creating of SFU fifo special files cifs: Update SFU comments about fifos and sockets fs/smb/client/cifspdu.h | 6 --- fs/smb/client/cifsproto.h | 4 ++ fs/smb/client/cifssmb.c | 8 ++-- fs/smb/client/fs_context.c | 13 ++++--- fs/smb/client/link.c | 3 ++ fs/smb/client/smb1ops.c | 2 +- fs/smb/client/smb2ops.c | 79 +++++++++++++++++++++++++++++--------- 7 files changed, 80 insertions(+), 35 deletions(-) -- 2.20.1
Linux cifs client can already detect SFU symlinks and reads it content
(target location). But currently is not able to create new symlink. So
implement this missing support.
When 'sfu' mount option is specified and 'mfsymlinks' is not specified then
create new symlinks in SFU-style. This will provide full SFU compatibility
of symlinks when mounting cifs share with 'sfu' option. 'mfsymlinks' option
override SFU for better Apple compatibility as explained in fs_context.c
file in smb3_update_mnt_flags() function.
Extend __cifs_sfu_make_node() function, which now can handle also S_IFLNK
type and refactor structures passed to sync_write() in this function, by
splitting SFU type and SFU data from original combined struct win_dev as
combined fixed-length struct cannot be used for variable-length symlinks.
Signed-off-by: Pali Rohár <pali@kernel.org>
---
fs/smb/client/cifspdu.h | 6 ---
fs/smb/client/cifsproto.h | 4 ++
fs/smb/client/fs_context.c | 13 ++++---
fs/smb/client/link.c | 3 ++
fs/smb/client/smb2ops.c | 80 +++++++++++++++++++++++++++++---------
5 files changed, 77 insertions(+), 29 deletions(-)
diff --git a/fs/smb/client/cifspdu.h b/fs/smb/client/cifspdu.h
index a2072ab9e586..c3b6263060b0 100644
--- a/fs/smb/client/cifspdu.h
+++ b/fs/smb/client/cifspdu.h
@@ -2573,12 +2573,6 @@ typedef struct {
} __attribute__((packed)) FIND_FILE_STANDARD_INFO; /* level 0x1 FF resp data */
-struct win_dev {
- unsigned char type[8]; /* IntxCHR or IntxBLK or LnxFIFO or LnxSOCK */
- __le64 major;
- __le64 minor;
-} __attribute__((packed));
-
struct fea {
unsigned char EA_flags;
__u8 name_len;
diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index 497bf3c447bc..791bddac0396 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -676,6 +676,10 @@ char *extract_sharename(const char *unc);
int parse_reparse_point(struct reparse_data_buffer *buf,
u32 plen, struct cifs_sb_info *cifs_sb,
bool unicode, struct cifs_open_info_data *data);
+int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
+ struct dentry *dentry, struct cifs_tcon *tcon,
+ const char *full_path, umode_t mode, dev_t dev,
+ const char *symname);
int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
struct dentry *dentry, struct cifs_tcon *tcon,
const char *full_path, umode_t mode, dev_t dev);
diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index bc926ab2555b..2f0c3894b0f7 100644
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -1896,14 +1896,17 @@ void smb3_update_mnt_flags(struct cifs_sb_info *cifs_sb)
if (ctx->mfsymlinks) {
if (ctx->sfu_emul) {
/*
- * Our SFU ("Services for Unix" emulation does not allow
- * creating symlinks but does allow reading existing SFU
- * symlinks (it does allow both creating and reading SFU
- * style mknod and FIFOs though). When "mfsymlinks" and
+ * Our SFU ("Services for Unix") emulation allows now
+ * creating new and reading existing SFU symlinks.
+ * Older Linux kernel versions were not able to neither
+ * read existing nor create new SFU symlinks. But
+ * creating and reading SFU style mknod and FIFOs was
+ * supported for long time. When "mfsymlinks" and
* "sfu" are both enabled at the same time, it allows
* reading both types of symlinks, but will only create
* them with mfsymlinks format. This allows better
- * Apple compatibility (probably better for Samba too)
+ * Apple compatibility, compatibility with older Linux
+ * kernel clients (probably better for Samba too)
* while still recognizing old Windows style symlinks.
*/
cifs_dbg(VFS, "mount options mfsymlinks and sfu both enabled\n");
diff --git a/fs/smb/client/link.c b/fs/smb/client/link.c
index 80099bbb333b..47ddeb7fa111 100644
--- a/fs/smb/client/link.c
+++ b/fs/smb/client/link.c
@@ -606,6 +606,9 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
/* BB what if DFS and this volume is on different share? BB */
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) {
rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
+ } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
+ rc = __cifs_sfu_make_node(xid, inode, direntry, pTcon,
+ full_path, S_IFLNK, 0, symname);
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
} else if (pTcon->unix_ext) {
rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 9c2d065d3cc4..2c251e9a3a30 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -5055,9 +5055,10 @@ static int smb2_next_header(struct TCP_Server_Info *server, char *buf,
return 0;
}
-static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
+int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
struct dentry *dentry, struct cifs_tcon *tcon,
- const char *full_path, umode_t mode, dev_t dev)
+ const char *full_path, umode_t mode, dev_t dev,
+ const char *symname)
{
struct TCP_Server_Info *server = tcon->ses->server;
struct cifs_open_parms oparms;
@@ -5065,30 +5066,64 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifs_fid fid;
unsigned int bytes_written;
- struct win_dev pdev = {};
- struct kvec iov[2];
+ u8 type[8];
+ int type_len = 0;
+ struct {
+ __le64 major;
+ __le64 minor;
+ } __packed pdev = {};
+ __le16 *symname_utf16 = NULL;
+ u8 *data = NULL;
+ int data_len = 0;
+ struct kvec iov[3];
__u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
int rc;
switch (mode & S_IFMT) {
case S_IFCHR:
- memcpy(pdev.type, "IntxCHR\0", 8);
+ type_len = 8;
+ memcpy(type, "IntxCHR\0", type_len);
pdev.major = cpu_to_le64(MAJOR(dev));
pdev.minor = cpu_to_le64(MINOR(dev));
+ data = (u8 *)&pdev;
+ data_len = sizeof(pdev);
break;
case S_IFBLK:
- memcpy(pdev.type, "IntxBLK\0", 8);
+ type_len = 8;
+ memcpy(type, "IntxBLK\0", type_len);
pdev.major = cpu_to_le64(MAJOR(dev));
pdev.minor = cpu_to_le64(MINOR(dev));
+ data = (u8 *)&pdev;
+ data_len = sizeof(pdev);
+ break;
+ case S_IFLNK:
+ type_len = 8;
+ memcpy(type, "IntxLNK\1", type_len);
+ symname_utf16 = cifs_strndup_to_utf16(symname, strlen(symname),
+ &data_len, cifs_sb->local_nls,
+ NO_MAP_UNI_RSVD);
+ if (!symname_utf16) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ data_len -= 2; /* symlink is without trailing wide-nul */
+ data = (u8 *)symname_utf16;
break;
case S_IFSOCK:
- strscpy(pdev.type, "LnxSOCK");
+ type_len = 8;
+ strscpy(type, "LnxSOCK");
+ data = (u8 *)&pdev;
+ data_len = sizeof(pdev);
break;
case S_IFIFO:
- strscpy(pdev.type, "LnxFIFO");
+ type_len = 8;
+ strscpy(type, "LnxFIFO");
+ data = (u8 *)&pdev;
+ data_len = sizeof(pdev);
break;
default:
- return -EPERM;
+ rc = -EPERM;
+ goto out;
}
oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, GENERIC_WRITE,
@@ -5098,17 +5133,26 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
rc = server->ops->open(xid, &oparms, &oplock, NULL);
if (rc)
- return rc;
+ goto out;
- io_parms.pid = current->tgid;
- io_parms.tcon = tcon;
- io_parms.length = sizeof(pdev);
- iov[1].iov_base = &pdev;
- iov[1].iov_len = sizeof(pdev);
+ if (type_len + data_len > 0) {
+ io_parms.pid = current->tgid;
+ io_parms.tcon = tcon;
+ io_parms.length = type_len + data_len;
+ iov[1].iov_base = type;
+ iov[1].iov_len = type_len;
+ iov[2].iov_base = data;
+ iov[2].iov_len = data_len;
+
+ rc = server->ops->sync_write(xid, &fid, &io_parms,
+ &bytes_written,
+ iov, ARRAY_SIZE(iov)-1);
+ }
- rc = server->ops->sync_write(xid, &fid, &io_parms,
- &bytes_written, iov, 1);
server->ops->close(xid, tcon, &fid);
+
+out:
+ kfree(symname_utf16);
return rc;
}
@@ -5120,7 +5164,7 @@ int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
int rc;
rc = __cifs_sfu_make_node(xid, inode, dentry, tcon,
- full_path, mode, dev);
+ full_path, mode, dev, NULL);
if (rc)
return rc;
--
2.20.1
Hi Pali,
On 09/15, Pali Rohár wrote:
>Linux cifs client can already detect SFU symlinks and reads it content
>(target location). But currently is not able to create new symlink. So
>implement this missing support.
>
>When 'sfu' mount option is specified and 'mfsymlinks' is not specified then
>create new symlinks in SFU-style. This will provide full SFU compatibility
>of symlinks when mounting cifs share with 'sfu' option. 'mfsymlinks' option
>override SFU for better Apple compatibility as explained in fs_context.c
>file in smb3_update_mnt_flags() function.
>
>Extend __cifs_sfu_make_node() function, which now can handle also S_IFLNK
>type and refactor structures passed to sync_write() in this function, by
>splitting SFU type and SFU data from original combined struct win_dev as
>combined fixed-length struct cannot be used for variable-length symlinks.
>
>Signed-off-by: Pali Rohár <pali@kernel.org>
>---
> fs/smb/client/cifspdu.h | 6 ---
> fs/smb/client/cifsproto.h | 4 ++
> fs/smb/client/fs_context.c | 13 ++++---
> fs/smb/client/link.c | 3 ++
> fs/smb/client/smb2ops.c | 80 +++++++++++++++++++++++++++++---------
> 5 files changed, 77 insertions(+), 29 deletions(-)
>
>diff --git a/fs/smb/client/cifspdu.h b/fs/smb/client/cifspdu.h
>index a2072ab9e586..c3b6263060b0 100644
>--- a/fs/smb/client/cifspdu.h
>+++ b/fs/smb/client/cifspdu.h
>@@ -2573,12 +2573,6 @@ typedef struct {
> } __attribute__((packed)) FIND_FILE_STANDARD_INFO; /* level 0x1 FF resp data */
>
>
>-struct win_dev {
>- unsigned char type[8]; /* IntxCHR or IntxBLK or LnxFIFO or LnxSOCK */
>- __le64 major;
>- __le64 minor;
>-} __attribute__((packed));
>-
> struct fea {
> unsigned char EA_flags;
> __u8 name_len;
>diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
>index 497bf3c447bc..791bddac0396 100644
>--- a/fs/smb/client/cifsproto.h
>+++ b/fs/smb/client/cifsproto.h
>@@ -676,6 +676,10 @@ char *extract_sharename(const char *unc);
> int parse_reparse_point(struct reparse_data_buffer *buf,
> u32 plen, struct cifs_sb_info *cifs_sb,
> bool unicode, struct cifs_open_info_data *data);
>+int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
>+ struct dentry *dentry, struct cifs_tcon *tcon,
>+ const char *full_path, umode_t mode, dev_t dev,
>+ const char *symname);
> int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct dentry *dentry, struct cifs_tcon *tcon,
> const char *full_path, umode_t mode, dev_t dev);
>diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
>index bc926ab2555b..2f0c3894b0f7 100644
>--- a/fs/smb/client/fs_context.c
>+++ b/fs/smb/client/fs_context.c
>@@ -1896,14 +1896,17 @@ void smb3_update_mnt_flags(struct cifs_sb_info *cifs_sb)
> if (ctx->mfsymlinks) {
> if (ctx->sfu_emul) {
> /*
>- * Our SFU ("Services for Unix" emulation does not allow
>- * creating symlinks but does allow reading existing SFU
>- * symlinks (it does allow both creating and reading SFU
>- * style mknod and FIFOs though). When "mfsymlinks" and
>+ * Our SFU ("Services for Unix") emulation allows now
>+ * creating new and reading existing SFU symlinks.
>+ * Older Linux kernel versions were not able to neither
>+ * read existing nor create new SFU symlinks. But
>+ * creating and reading SFU style mknod and FIFOs was
>+ * supported for long time. When "mfsymlinks" and
> * "sfu" are both enabled at the same time, it allows
> * reading both types of symlinks, but will only create
> * them with mfsymlinks format. This allows better
>- * Apple compatibility (probably better for Samba too)
>+ * Apple compatibility, compatibility with older Linux
>+ * kernel clients (probably better for Samba too)
> * while still recognizing old Windows style symlinks.
> */
> cifs_dbg(VFS, "mount options mfsymlinks and sfu both enabled\n");
>diff --git a/fs/smb/client/link.c b/fs/smb/client/link.c
>index 80099bbb333b..47ddeb7fa111 100644
>--- a/fs/smb/client/link.c
>+++ b/fs/smb/client/link.c
>@@ -606,6 +606,9 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
> /* BB what if DFS and this volume is on different share? BB */
> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) {
> rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
>+ } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
>+ rc = __cifs_sfu_make_node(xid, inode, direntry, pTcon,
>+ full_path, S_IFLNK, 0, symname);
> #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
> } else if (pTcon->unix_ext) {
> rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
>diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
>index 9c2d065d3cc4..2c251e9a3a30 100644
>--- a/fs/smb/client/smb2ops.c
>+++ b/fs/smb/client/smb2ops.c
>@@ -5055,9 +5055,10 @@ static int smb2_next_header(struct TCP_Server_Info *server, char *buf,
> return 0;
> }
>
>-static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
>+int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct dentry *dentry, struct cifs_tcon *tcon,
>- const char *full_path, umode_t mode, dev_t dev)
>+ const char *full_path, umode_t mode, dev_t dev,
>+ const char *symname)
> {
> struct TCP_Server_Info *server = tcon->ses->server;
> struct cifs_open_parms oparms;
>@@ -5065,30 +5066,64 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
> struct cifs_fid fid;
> unsigned int bytes_written;
>- struct win_dev pdev = {};
>- struct kvec iov[2];
>+ u8 type[8];
>+ int type_len = 0;
>+ struct {
>+ __le64 major;
>+ __le64 minor;
>+ } __packed pdev = {};
>+ __le16 *symname_utf16 = NULL;
>+ u8 *data = NULL;
>+ int data_len = 0;
>+ struct kvec iov[3];
> __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> int rc;
>
> switch (mode & S_IFMT) {
> case S_IFCHR:
>- memcpy(pdev.type, "IntxCHR\0", 8);
>+ type_len = 8;
>+ memcpy(type, "IntxCHR\0", type_len);
> pdev.major = cpu_to_le64(MAJOR(dev));
> pdev.minor = cpu_to_le64(MINOR(dev));
>+ data = (u8 *)&pdev;
>+ data_len = sizeof(pdev);
> break;
> case S_IFBLK:
>- memcpy(pdev.type, "IntxBLK\0", 8);
>+ type_len = 8;
>+ memcpy(type, "IntxBLK\0", type_len);
> pdev.major = cpu_to_le64(MAJOR(dev));
> pdev.minor = cpu_to_le64(MINOR(dev));
>+ data = (u8 *)&pdev;
>+ data_len = sizeof(pdev);
>+ break;
>+ case S_IFLNK:
>+ type_len = 8;
>+ memcpy(type, "IntxLNK\1", type_len);
>+ symname_utf16 = cifs_strndup_to_utf16(symname, strlen(symname),
>+ &data_len, cifs_sb->local_nls,
>+ NO_MAP_UNI_RSVD);
>+ if (!symname_utf16) {
>+ rc = -ENOMEM;
>+ goto out;
>+ }
>+ data_len -= 2; /* symlink is without trailing wide-nul */
>+ data = (u8 *)symname_utf16;
Can't S_IFLNK be handled somewhere else/other function? mknod doesn't
support S_IFLNK, so this seems out of place.
And even though it's unreachable (AFAICS), cifs_sfu_make_node() calls
this with @symname == NULL (caught with gcc -fanalyzer).
Cheers,
Enzo
> break;
> case S_IFSOCK:
>- strscpy(pdev.type, "LnxSOCK");
>+ type_len = 8;
>+ strscpy(type, "LnxSOCK");
>+ data = (u8 *)&pdev;
>+ data_len = sizeof(pdev);
> break;
> case S_IFIFO:
>- strscpy(pdev.type, "LnxFIFO");
>+ type_len = 8;
>+ strscpy(type, "LnxFIFO");
>+ data = (u8 *)&pdev;
>+ data_len = sizeof(pdev);
> break;
> default:
>- return -EPERM;
>+ rc = -EPERM;
>+ goto out;
> }
>
> oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, GENERIC_WRITE,
>@@ -5098,17 +5133,26 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
>
> rc = server->ops->open(xid, &oparms, &oplock, NULL);
> if (rc)
>- return rc;
>+ goto out;
>
>- io_parms.pid = current->tgid;
>- io_parms.tcon = tcon;
>- io_parms.length = sizeof(pdev);
>- iov[1].iov_base = &pdev;
>- iov[1].iov_len = sizeof(pdev);
>+ if (type_len + data_len > 0) {
>+ io_parms.pid = current->tgid;
>+ io_parms.tcon = tcon;
>+ io_parms.length = type_len + data_len;
>+ iov[1].iov_base = type;
>+ iov[1].iov_len = type_len;
>+ iov[2].iov_base = data;
>+ iov[2].iov_len = data_len;
>+
>+ rc = server->ops->sync_write(xid, &fid, &io_parms,
>+ &bytes_written,
>+ iov, ARRAY_SIZE(iov)-1);
>+ }
>
>- rc = server->ops->sync_write(xid, &fid, &io_parms,
>- &bytes_written, iov, 1);
> server->ops->close(xid, tcon, &fid);
>+
>+out:
>+ kfree(symname_utf16);
> return rc;
> }
>
>@@ -5120,7 +5164,7 @@ int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> int rc;
>
> rc = __cifs_sfu_make_node(xid, inode, dentry, tcon,
>- full_path, mode, dev);
>+ full_path, mode, dev, NULL);
> if (rc)
> return rc;
On Friday 27 September 2024 14:54:31 Enzo Matsumiya wrote:
> Hi Pali,
>
> On 09/15, Pali Rohár wrote:
> > Linux cifs client can already detect SFU symlinks and reads it content
> > (target location). But currently is not able to create new symlink. So
> > implement this missing support.
> >
> > When 'sfu' mount option is specified and 'mfsymlinks' is not specified then
> > create new symlinks in SFU-style. This will provide full SFU compatibility
> > of symlinks when mounting cifs share with 'sfu' option. 'mfsymlinks' option
> > override SFU for better Apple compatibility as explained in fs_context.c
> > file in smb3_update_mnt_flags() function.
> >
> > Extend __cifs_sfu_make_node() function, which now can handle also S_IFLNK
> > type and refactor structures passed to sync_write() in this function, by
> > splitting SFU type and SFU data from original combined struct win_dev as
> > combined fixed-length struct cannot be used for variable-length symlinks.
> >
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > ---
> > fs/smb/client/cifspdu.h | 6 ---
> > fs/smb/client/cifsproto.h | 4 ++
> > fs/smb/client/fs_context.c | 13 ++++---
> > fs/smb/client/link.c | 3 ++
> > fs/smb/client/smb2ops.c | 80 +++++++++++++++++++++++++++++---------
> > 5 files changed, 77 insertions(+), 29 deletions(-)
> >
> > diff --git a/fs/smb/client/cifspdu.h b/fs/smb/client/cifspdu.h
> > index a2072ab9e586..c3b6263060b0 100644
> > --- a/fs/smb/client/cifspdu.h
> > +++ b/fs/smb/client/cifspdu.h
> > @@ -2573,12 +2573,6 @@ typedef struct {
> > } __attribute__((packed)) FIND_FILE_STANDARD_INFO; /* level 0x1 FF resp data */
> >
> >
> > -struct win_dev {
> > - unsigned char type[8]; /* IntxCHR or IntxBLK or LnxFIFO or LnxSOCK */
> > - __le64 major;
> > - __le64 minor;
> > -} __attribute__((packed));
> > -
> > struct fea {
> > unsigned char EA_flags;
> > __u8 name_len;
> > diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
> > index 497bf3c447bc..791bddac0396 100644
> > --- a/fs/smb/client/cifsproto.h
> > +++ b/fs/smb/client/cifsproto.h
> > @@ -676,6 +676,10 @@ char *extract_sharename(const char *unc);
> > int parse_reparse_point(struct reparse_data_buffer *buf,
> > u32 plen, struct cifs_sb_info *cifs_sb,
> > bool unicode, struct cifs_open_info_data *data);
> > +int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > + struct dentry *dentry, struct cifs_tcon *tcon,
> > + const char *full_path, umode_t mode, dev_t dev,
> > + const char *symname);
> > int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > struct dentry *dentry, struct cifs_tcon *tcon,
> > const char *full_path, umode_t mode, dev_t dev);
> > diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
> > index bc926ab2555b..2f0c3894b0f7 100644
> > --- a/fs/smb/client/fs_context.c
> > +++ b/fs/smb/client/fs_context.c
> > @@ -1896,14 +1896,17 @@ void smb3_update_mnt_flags(struct cifs_sb_info *cifs_sb)
> > if (ctx->mfsymlinks) {
> > if (ctx->sfu_emul) {
> > /*
> > - * Our SFU ("Services for Unix" emulation does not allow
> > - * creating symlinks but does allow reading existing SFU
> > - * symlinks (it does allow both creating and reading SFU
> > - * style mknod and FIFOs though). When "mfsymlinks" and
> > + * Our SFU ("Services for Unix") emulation allows now
> > + * creating new and reading existing SFU symlinks.
> > + * Older Linux kernel versions were not able to neither
> > + * read existing nor create new SFU symlinks. But
> > + * creating and reading SFU style mknod and FIFOs was
> > + * supported for long time. When "mfsymlinks" and
> > * "sfu" are both enabled at the same time, it allows
> > * reading both types of symlinks, but will only create
> > * them with mfsymlinks format. This allows better
> > - * Apple compatibility (probably better for Samba too)
> > + * Apple compatibility, compatibility with older Linux
> > + * kernel clients (probably better for Samba too)
> > * while still recognizing old Windows style symlinks.
> > */
> > cifs_dbg(VFS, "mount options mfsymlinks and sfu both enabled\n");
> > diff --git a/fs/smb/client/link.c b/fs/smb/client/link.c
> > index 80099bbb333b..47ddeb7fa111 100644
> > --- a/fs/smb/client/link.c
> > +++ b/fs/smb/client/link.c
> > @@ -606,6 +606,9 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
> > /* BB what if DFS and this volume is on different share? BB */
> > if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) {
> > rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
> > + } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> > + rc = __cifs_sfu_make_node(xid, inode, direntry, pTcon,
> > + full_path, S_IFLNK, 0, symname);
> > #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
> > } else if (pTcon->unix_ext) {
> > rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
> > diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> > index 9c2d065d3cc4..2c251e9a3a30 100644
> > --- a/fs/smb/client/smb2ops.c
> > +++ b/fs/smb/client/smb2ops.c
> > @@ -5055,9 +5055,10 @@ static int smb2_next_header(struct TCP_Server_Info *server, char *buf,
> > return 0;
> > }
> >
> > -static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > +int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > struct dentry *dentry, struct cifs_tcon *tcon,
> > - const char *full_path, umode_t mode, dev_t dev)
> > + const char *full_path, umode_t mode, dev_t dev,
> > + const char *symname)
> > {
> > struct TCP_Server_Info *server = tcon->ses->server;
> > struct cifs_open_parms oparms;
> > @@ -5065,30 +5066,64 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
> > struct cifs_fid fid;
> > unsigned int bytes_written;
> > - struct win_dev pdev = {};
> > - struct kvec iov[2];
> > + u8 type[8];
> > + int type_len = 0;
> > + struct {
> > + __le64 major;
> > + __le64 minor;
> > + } __packed pdev = {};
> > + __le16 *symname_utf16 = NULL;
> > + u8 *data = NULL;
> > + int data_len = 0;
> > + struct kvec iov[3];
> > __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> > int rc;
> >
> > switch (mode & S_IFMT) {
> > case S_IFCHR:
> > - memcpy(pdev.type, "IntxCHR\0", 8);
> > + type_len = 8;
> > + memcpy(type, "IntxCHR\0", type_len);
> > pdev.major = cpu_to_le64(MAJOR(dev));
> > pdev.minor = cpu_to_le64(MINOR(dev));
> > + data = (u8 *)&pdev;
> > + data_len = sizeof(pdev);
> > break;
> > case S_IFBLK:
> > - memcpy(pdev.type, "IntxBLK\0", 8);
> > + type_len = 8;
> > + memcpy(type, "IntxBLK\0", type_len);
> > pdev.major = cpu_to_le64(MAJOR(dev));
> > pdev.minor = cpu_to_le64(MINOR(dev));
> > + data = (u8 *)&pdev;
> > + data_len = sizeof(pdev);
> > + break;
> > + case S_IFLNK:
> > + type_len = 8;
> > + memcpy(type, "IntxLNK\1", type_len);
> > + symname_utf16 = cifs_strndup_to_utf16(symname, strlen(symname),
> > + &data_len, cifs_sb->local_nls,
> > + NO_MAP_UNI_RSVD);
> > + if (!symname_utf16) {
> > + rc = -ENOMEM;
> > + goto out;
> > + }
> > + data_len -= 2; /* symlink is without trailing wide-nul */
> > + data = (u8 *)symname_utf16;
>
> Can't S_IFLNK be handled somewhere else/other function? mknod doesn't
> support S_IFLNK, so this seems out of place.
>
> And even though it's unreachable (AFAICS), cifs_sfu_make_node() calls
> this with @symname == NULL (caught with gcc -fanalyzer).
>
>
> Cheers,
>
> Enzo
Hello! As SFU-style special files have same format, I just extended this
function which handles all SFU types, to handle also symlink.
I wanted to reuse existing function instead of copying and duplicating
code.
Parameter symname is used only for S_IFLNK, so this should be safe. And
as you pointed out mknod does not support S_IFLNK, so mknod code path
would not call __cifs_sfu_make_node() function with S_IFLNK argument.
So I think that there is not issue. But if you want to refactor this
code, do you have an idea what to do?
> > break;
> > case S_IFSOCK:
> > - strscpy(pdev.type, "LnxSOCK");
> > + type_len = 8;
> > + strscpy(type, "LnxSOCK");
> > + data = (u8 *)&pdev;
> > + data_len = sizeof(pdev);
> > break;
> > case S_IFIFO:
> > - strscpy(pdev.type, "LnxFIFO");
> > + type_len = 8;
> > + strscpy(type, "LnxFIFO");
> > + data = (u8 *)&pdev;
> > + data_len = sizeof(pdev);
> > break;
> > default:
> > - return -EPERM;
> > + rc = -EPERM;
> > + goto out;
> > }
> >
> > oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, GENERIC_WRITE,
> > @@ -5098,17 +5133,26 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> >
> > rc = server->ops->open(xid, &oparms, &oplock, NULL);
> > if (rc)
> > - return rc;
> > + goto out;
> >
> > - io_parms.pid = current->tgid;
> > - io_parms.tcon = tcon;
> > - io_parms.length = sizeof(pdev);
> > - iov[1].iov_base = &pdev;
> > - iov[1].iov_len = sizeof(pdev);
> > + if (type_len + data_len > 0) {
> > + io_parms.pid = current->tgid;
> > + io_parms.tcon = tcon;
> > + io_parms.length = type_len + data_len;
> > + iov[1].iov_base = type;
> > + iov[1].iov_len = type_len;
> > + iov[2].iov_base = data;
> > + iov[2].iov_len = data_len;
> > +
> > + rc = server->ops->sync_write(xid, &fid, &io_parms,
> > + &bytes_written,
> > + iov, ARRAY_SIZE(iov)-1);
> > + }
> >
> > - rc = server->ops->sync_write(xid, &fid, &io_parms,
> > - &bytes_written, iov, 1);
> > server->ops->close(xid, tcon, &fid);
> > +
> > +out:
> > + kfree(symname_utf16);
> > return rc;
> > }
> >
> > @@ -5120,7 +5164,7 @@ int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > int rc;
> >
> > rc = __cifs_sfu_make_node(xid, inode, dentry, tcon,
> > - full_path, mode, dev);
> > + full_path, mode, dev, NULL);
> > if (rc)
> > return rc;
merged into cifs-2.6.git for-next pending review/testing
On Sun, Sep 15, 2024 at 2:46 PM Pali Rohár <pali@kernel.org> wrote:
>
> Linux cifs client can already detect SFU symlinks and reads it content
> (target location). But currently is not able to create new symlink. So
> implement this missing support.
>
> When 'sfu' mount option is specified and 'mfsymlinks' is not specified then
> create new symlinks in SFU-style. This will provide full SFU compatibility
> of symlinks when mounting cifs share with 'sfu' option. 'mfsymlinks' option
> override SFU for better Apple compatibility as explained in fs_context.c
> file in smb3_update_mnt_flags() function.
>
> Extend __cifs_sfu_make_node() function, which now can handle also S_IFLNK
> type and refactor structures passed to sync_write() in this function, by
> splitting SFU type and SFU data from original combined struct win_dev as
> combined fixed-length struct cannot be used for variable-length symlinks.
>
> Signed-off-by: Pali Rohár <pali@kernel.org>
> ---
> fs/smb/client/cifspdu.h | 6 ---
> fs/smb/client/cifsproto.h | 4 ++
> fs/smb/client/fs_context.c | 13 ++++---
> fs/smb/client/link.c | 3 ++
> fs/smb/client/smb2ops.c | 80 +++++++++++++++++++++++++++++---------
> 5 files changed, 77 insertions(+), 29 deletions(-)
>
> diff --git a/fs/smb/client/cifspdu.h b/fs/smb/client/cifspdu.h
> index a2072ab9e586..c3b6263060b0 100644
> --- a/fs/smb/client/cifspdu.h
> +++ b/fs/smb/client/cifspdu.h
> @@ -2573,12 +2573,6 @@ typedef struct {
> } __attribute__((packed)) FIND_FILE_STANDARD_INFO; /* level 0x1 FF resp data */
>
>
> -struct win_dev {
> - unsigned char type[8]; /* IntxCHR or IntxBLK or LnxFIFO or LnxSOCK */
> - __le64 major;
> - __le64 minor;
> -} __attribute__((packed));
> -
> struct fea {
> unsigned char EA_flags;
> __u8 name_len;
> diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
> index 497bf3c447bc..791bddac0396 100644
> --- a/fs/smb/client/cifsproto.h
> +++ b/fs/smb/client/cifsproto.h
> @@ -676,6 +676,10 @@ char *extract_sharename(const char *unc);
> int parse_reparse_point(struct reparse_data_buffer *buf,
> u32 plen, struct cifs_sb_info *cifs_sb,
> bool unicode, struct cifs_open_info_data *data);
> +int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> + struct dentry *dentry, struct cifs_tcon *tcon,
> + const char *full_path, umode_t mode, dev_t dev,
> + const char *symname);
> int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct dentry *dentry, struct cifs_tcon *tcon,
> const char *full_path, umode_t mode, dev_t dev);
> diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
> index bc926ab2555b..2f0c3894b0f7 100644
> --- a/fs/smb/client/fs_context.c
> +++ b/fs/smb/client/fs_context.c
> @@ -1896,14 +1896,17 @@ void smb3_update_mnt_flags(struct cifs_sb_info *cifs_sb)
> if (ctx->mfsymlinks) {
> if (ctx->sfu_emul) {
> /*
> - * Our SFU ("Services for Unix" emulation does not allow
> - * creating symlinks but does allow reading existing SFU
> - * symlinks (it does allow both creating and reading SFU
> - * style mknod and FIFOs though). When "mfsymlinks" and
> + * Our SFU ("Services for Unix") emulation allows now
> + * creating new and reading existing SFU symlinks.
> + * Older Linux kernel versions were not able to neither
> + * read existing nor create new SFU symlinks. But
> + * creating and reading SFU style mknod and FIFOs was
> + * supported for long time. When "mfsymlinks" and
> * "sfu" are both enabled at the same time, it allows
> * reading both types of symlinks, but will only create
> * them with mfsymlinks format. This allows better
> - * Apple compatibility (probably better for Samba too)
> + * Apple compatibility, compatibility with older Linux
> + * kernel clients (probably better for Samba too)
> * while still recognizing old Windows style symlinks.
> */
> cifs_dbg(VFS, "mount options mfsymlinks and sfu both enabled\n");
> diff --git a/fs/smb/client/link.c b/fs/smb/client/link.c
> index 80099bbb333b..47ddeb7fa111 100644
> --- a/fs/smb/client/link.c
> +++ b/fs/smb/client/link.c
> @@ -606,6 +606,9 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
> /* BB what if DFS and this volume is on different share? BB */
> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS) {
> rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
> + } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> + rc = __cifs_sfu_make_node(xid, inode, direntry, pTcon,
> + full_path, S_IFLNK, 0, symname);
> #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
> } else if (pTcon->unix_ext) {
> rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> index 9c2d065d3cc4..2c251e9a3a30 100644
> --- a/fs/smb/client/smb2ops.c
> +++ b/fs/smb/client/smb2ops.c
> @@ -5055,9 +5055,10 @@ static int smb2_next_header(struct TCP_Server_Info *server, char *buf,
> return 0;
> }
>
> -static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> +int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct dentry *dentry, struct cifs_tcon *tcon,
> - const char *full_path, umode_t mode, dev_t dev)
> + const char *full_path, umode_t mode, dev_t dev,
> + const char *symname)
> {
> struct TCP_Server_Info *server = tcon->ses->server;
> struct cifs_open_parms oparms;
> @@ -5065,30 +5066,64 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
> struct cifs_fid fid;
> unsigned int bytes_written;
> - struct win_dev pdev = {};
> - struct kvec iov[2];
> + u8 type[8];
> + int type_len = 0;
> + struct {
> + __le64 major;
> + __le64 minor;
> + } __packed pdev = {};
> + __le16 *symname_utf16 = NULL;
> + u8 *data = NULL;
> + int data_len = 0;
> + struct kvec iov[3];
> __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> int rc;
>
> switch (mode & S_IFMT) {
> case S_IFCHR:
> - memcpy(pdev.type, "IntxCHR\0", 8);
> + type_len = 8;
> + memcpy(type, "IntxCHR\0", type_len);
> pdev.major = cpu_to_le64(MAJOR(dev));
> pdev.minor = cpu_to_le64(MINOR(dev));
> + data = (u8 *)&pdev;
> + data_len = sizeof(pdev);
> break;
> case S_IFBLK:
> - memcpy(pdev.type, "IntxBLK\0", 8);
> + type_len = 8;
> + memcpy(type, "IntxBLK\0", type_len);
> pdev.major = cpu_to_le64(MAJOR(dev));
> pdev.minor = cpu_to_le64(MINOR(dev));
> + data = (u8 *)&pdev;
> + data_len = sizeof(pdev);
> + break;
> + case S_IFLNK:
> + type_len = 8;
> + memcpy(type, "IntxLNK\1", type_len);
> + symname_utf16 = cifs_strndup_to_utf16(symname, strlen(symname),
> + &data_len, cifs_sb->local_nls,
> + NO_MAP_UNI_RSVD);
> + if (!symname_utf16) {
> + rc = -ENOMEM;
> + goto out;
> + }
> + data_len -= 2; /* symlink is without trailing wide-nul */
> + data = (u8 *)symname_utf16;
> break;
> case S_IFSOCK:
> - strscpy(pdev.type, "LnxSOCK");
> + type_len = 8;
> + strscpy(type, "LnxSOCK");
> + data = (u8 *)&pdev;
> + data_len = sizeof(pdev);
> break;
> case S_IFIFO:
> - strscpy(pdev.type, "LnxFIFO");
> + type_len = 8;
> + strscpy(type, "LnxFIFO");
> + data = (u8 *)&pdev;
> + data_len = sizeof(pdev);
> break;
> default:
> - return -EPERM;
> + rc = -EPERM;
> + goto out;
> }
>
> oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, GENERIC_WRITE,
> @@ -5098,17 +5133,26 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
>
> rc = server->ops->open(xid, &oparms, &oplock, NULL);
> if (rc)
> - return rc;
> + goto out;
>
> - io_parms.pid = current->tgid;
> - io_parms.tcon = tcon;
> - io_parms.length = sizeof(pdev);
> - iov[1].iov_base = &pdev;
> - iov[1].iov_len = sizeof(pdev);
> + if (type_len + data_len > 0) {
> + io_parms.pid = current->tgid;
> + io_parms.tcon = tcon;
> + io_parms.length = type_len + data_len;
> + iov[1].iov_base = type;
> + iov[1].iov_len = type_len;
> + iov[2].iov_base = data;
> + iov[2].iov_len = data_len;
> +
> + rc = server->ops->sync_write(xid, &fid, &io_parms,
> + &bytes_written,
> + iov, ARRAY_SIZE(iov)-1);
> + }
>
> - rc = server->ops->sync_write(xid, &fid, &io_parms,
> - &bytes_written, iov, 1);
> server->ops->close(xid, tcon, &fid);
> +
> +out:
> + kfree(symname_utf16);
> return rc;
> }
>
> @@ -5120,7 +5164,7 @@ int cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> int rc;
>
> rc = __cifs_sfu_make_node(xid, inode, dentry, tcon,
> - full_path, mode, dev);
> + full_path, mode, dev, NULL);
> if (rc)
> return rc;
>
> --
> 2.20.1
>
>
--
Thanks,
Steve
SFU-style socket is file which has system attribute set and file content is
one zero byte. This format was introduced in Interix 3.0 subsystem, as part
of the Microsoft SFU 3.0 and is used also by all later versions. Previous
versions had no UNIX domain socket support.
This format of SFU-style sockets is recognized also by Windows NFS server
included in the latest version on Windows Server 2022.
Currently when sfu mount option is specified then CIFS creates new socket
files with content LnxSOCK. This was introduced in commit 518549c120e6
("cifs: fix creating sockets when using sfu mount options") as nobody
figured out what is the correct SFU format of sockets and tag LnxSOCK was
chosen to allow creating socket files. LnxSOCK looks similar to IntxCHR and
IntxBLK tags which are the proper SFU tags for char and block devices.
It is important to note that LnxSOCK is not SFU-compatible and neither
Interix, SFU, SUA or Windows NFS server recognize file with content of
LnxSOCK as special socket file.
Now when the proper format of SFU-style sockets is known and it was
verified that works with both old Interix 3.x subsystem and also with
Windows NFS server, change implementation of creating new SFU socket files
by CIFS client to be compatible with SFU.
518549c120e6 ("cifs: fix creating sockets when using sfu mount options")
Signed-off-by: Pali Rohár <pali@kernel.org>
---
fs/smb/client/smb2ops.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 2c251e9a3a30..dc56f7ba1a06 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -5110,10 +5110,9 @@ int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
data = (u8 *)symname_utf16;
break;
case S_IFSOCK:
- type_len = 8;
- strscpy(type, "LnxSOCK");
- data = (u8 *)&pdev;
- data_len = sizeof(pdev);
+ /* SFU socket is system file with one zero byte */
+ type_len = 1;
+ type[0] = '\0';
break;
case S_IFIFO:
type_len = 8;
--
2.20.1
SFU-style fifo is empty file with system attribute set. This format is used
by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
(which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
This format of SFU-style fifos is recognized also by Windows NFS server
included in the latest version on Windows Server 2022.
Currently when sfu mount option is specified then CIFS creates new fifo
files with content LnxFIFO. This was introduced in commit 72bc63f5e23a
("smb3: fix creating FIFOs when mounting with "sfu" mount option").
It is important to note that LnxFIFO is not SFU-compatible and neither
Interix, SFU, SUA or Windows NFS server recognize file with content of
LnxFIFO as special fifo file.
So when sfu mount option is specified, fix this problem and create all fifo
special files compatible with SFU format, as it is expected by sfu mount
option. This allows interoperability with other SFU implementations and
also with Windows NFS server.
Fixes: 72bc63f5e23a ("smb3: fix creating FIFOs when mounting with "sfu" mount option")
Signed-off-by: Pali Rohár <pali@kernel.org>
---
fs/smb/client/smb2ops.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index dc56f7ba1a06..406f2399f0c5 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -5115,10 +5115,8 @@ int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
type[0] = '\0';
break;
case S_IFIFO:
- type_len = 8;
- strscpy(type, "LnxFIFO");
- data = (u8 *)&pdev;
- data_len = sizeof(pdev);
+ /* SFU fifo is system file which is empty */
+ type_len = 0;
break;
default:
rc = -EPERM;
--
2.20.1
In SFU mode, activated by -o sfu mount option is now also support for
creating new fifos and sockets.
Signed-off-by: Pali Rohár <pali@kernel.org>
---
fs/smb/client/cifssmb.c | 8 ++++----
fs/smb/client/smb1ops.c | 2 +-
fs/smb/client/smb2ops.c | 2 +-
3 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index cfae2e918209..0ffc45aa5e2c 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
- /* set file as system file if special file such
- as fifo and server expecting SFU style and
+ /* set file as system file if special file such as fifo,
+ * socket, char or block and server expecting SFU style and
no Unix extensions */
if (create_options & CREATE_OPTION_SPECIAL)
@@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
req->AllocationSize = 0;
/*
- * Set file as system file if special file such as fifo and server
- * expecting SFU style and no Unix extensions.
+ * Set file as system file if special file such as fifo, socket, char
+ * or block and server expecting SFU style and no Unix extensions.
*/
if (create_options & CREATE_OPTION_SPECIAL)
req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
index e1f2feb56f45..e03c91a49650 100644
--- a/fs/smb/client/smb1ops.c
+++ b/fs/smb/client/smb1ops.c
@@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
/*
* Check if mounted with mount parm 'sfu' mount parm.
* SFU emulation should work with all servers, but only
- * supports block and char device (no socket & fifo),
+ * supports block and char device, socket & fifo,
* and was used by default in earlier versions of Windows
*/
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 406f2399f0c5..d30f7cab197e 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -5190,7 +5190,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
/*
* Check if mounted with mount parm 'sfu' mount parm.
* SFU emulation should work with all servers, but only
- * supports block and char device (no socket & fifo),
+ * supports block and char device, socket & fifo,
* and was used by default in earlier versions of Windows
*/
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
--
2.20.1
merged into cifs-2.6.git for-next
On Sun, Sep 15, 2024 at 2:46 PM Pali Rohár <pali@kernel.org> wrote:
>
> In SFU mode, activated by -o sfu mount option is now also support for
> creating new fifos and sockets.
>
> Signed-off-by: Pali Rohár <pali@kernel.org>
> ---
> fs/smb/client/cifssmb.c | 8 ++++----
> fs/smb/client/smb1ops.c | 2 +-
> fs/smb/client/smb2ops.c | 2 +-
> 3 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> index cfae2e918209..0ffc45aa5e2c 100644
> --- a/fs/smb/client/cifssmb.c
> +++ b/fs/smb/client/cifssmb.c
> @@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
> pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
> pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
> pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
> - /* set file as system file if special file such
> - as fifo and server expecting SFU style and
> + /* set file as system file if special file such as fifo,
> + * socket, char or block and server expecting SFU style and
> no Unix extensions */
>
> if (create_options & CREATE_OPTION_SPECIAL)
> @@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
> req->AllocationSize = 0;
>
> /*
> - * Set file as system file if special file such as fifo and server
> - * expecting SFU style and no Unix extensions.
> + * Set file as system file if special file such as fifo, socket, char
> + * or block and server expecting SFU style and no Unix extensions.
> */
> if (create_options & CREATE_OPTION_SPECIAL)
> req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
> diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> index e1f2feb56f45..e03c91a49650 100644
> --- a/fs/smb/client/smb1ops.c
> +++ b/fs/smb/client/smb1ops.c
> @@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
> /*
> * Check if mounted with mount parm 'sfu' mount parm.
> * SFU emulation should work with all servers, but only
> - * supports block and char device (no socket & fifo),
> + * supports block and char device, socket & fifo,
> * and was used by default in earlier versions of Windows
> */
> if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> index 406f2399f0c5..d30f7cab197e 100644
> --- a/fs/smb/client/smb2ops.c
> +++ b/fs/smb/client/smb2ops.c
> @@ -5190,7 +5190,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
> /*
> * Check if mounted with mount parm 'sfu' mount parm.
> * SFU emulation should work with all servers, but only
> - * supports block and char device (no socket & fifo),
> + * supports block and char device, socket & fifo,
> * and was used by default in earlier versions of Windows
> */
> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> --
> 2.20.1
>
>
--
Thanks,
Steve
On Thursday 12 September 2024 14:05:47 Pali Rohár wrote:
> SFU-style fifo is empty file with system attribute set. This format is used
> by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
> (which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
>
> SFU-style socket is file which has system attribute set and file content is
> one zero byte. This format was introduced in Interix 3.0 subsystem, as part
> of the Microsoft SFU 3.0 and is used also by all later versions. Previous
> versions had no UNIX domain socket support.
>
> Currently when sfu mount option is specified then CIFS creates fifo and
> socket special files with some strange LnxSOCK or LnxFIFO content which is
> not compatible with Microsoft SFU and neither recognized by other SMB
> implementations which have some SFU support, including older Linux cifs
> implementations.
>
> So when sfu mount option is specified, create all fifo and socket special
> files compatible with SFU format to achieve SFU interop, as it is expected
> by sfu mount option.
>
> Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 72bc63f5e23a ("smb3: fix creating FIFOs when mounting with "sfu" mount option")
Fixes: 518549c120e6 ("cifs: fix creating sockets when using sfu mount options")
I located commits which introduced those strange LnxSOCK or LnxFIFO
types which are not compatible with SFU. I would suggest to add those
two Fixes: tags into commit message for reference.
> ---
> fs/smb/client/cifssmb.c | 8 ++++----
> fs/smb/client/smb1ops.c | 2 +-
> fs/smb/client/smb2ops.c | 29 +++++++++++++++++++----------
> 3 files changed, 24 insertions(+), 15 deletions(-)
>
> diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> index cfae2e918209..0ffc45aa5e2c 100644
> --- a/fs/smb/client/cifssmb.c
> +++ b/fs/smb/client/cifssmb.c
> @@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
> pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
> pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
> pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
> - /* set file as system file if special file such
> - as fifo and server expecting SFU style and
> + /* set file as system file if special file such as fifo,
> + * socket, char or block and server expecting SFU style and
> no Unix extensions */
>
> if (create_options & CREATE_OPTION_SPECIAL)
> @@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
> req->AllocationSize = 0;
>
> /*
> - * Set file as system file if special file such as fifo and server
> - * expecting SFU style and no Unix extensions.
> + * Set file as system file if special file such as fifo, socket, char
> + * or block and server expecting SFU style and no Unix extensions.
> */
> if (create_options & CREATE_OPTION_SPECIAL)
> req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
> diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> index e1f2feb56f45..e03c91a49650 100644
> --- a/fs/smb/client/smb1ops.c
> +++ b/fs/smb/client/smb1ops.c
> @@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
> /*
> * Check if mounted with mount parm 'sfu' mount parm.
> * SFU emulation should work with all servers, but only
> - * supports block and char device (no socket & fifo),
> + * supports block and char device, socket & fifo,
> * and was used by default in earlier versions of Windows
> */
> if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> index 9c2d065d3cc4..9e90672caf60 100644
> --- a/fs/smb/client/smb2ops.c
> +++ b/fs/smb/client/smb2ops.c
> @@ -5066,26 +5066,32 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> struct cifs_fid fid;
> unsigned int bytes_written;
> struct win_dev pdev = {};
> + size_t pdev_len = 0;
> struct kvec iov[2];
> __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> int rc;
>
> switch (mode & S_IFMT) {
> case S_IFCHR:
> + pdev_len = sizeof(pdev);
> memcpy(pdev.type, "IntxCHR\0", 8);
> pdev.major = cpu_to_le64(MAJOR(dev));
> pdev.minor = cpu_to_le64(MINOR(dev));
> break;
> case S_IFBLK:
> + pdev_len = sizeof(pdev);
> memcpy(pdev.type, "IntxBLK\0", 8);
> pdev.major = cpu_to_le64(MAJOR(dev));
> pdev.minor = cpu_to_le64(MINOR(dev));
> break;
> case S_IFSOCK:
> - strscpy(pdev.type, "LnxSOCK");
> + /* SFU socket is system file with one zero byte */
> + pdev_len = 1;
> + pdev.type[0] = '\0';
> break;
> case S_IFIFO:
> - strscpy(pdev.type, "LnxFIFO");
> + /* SFU fifo is system file which is empty */
> + pdev_len = 0;
> break;
> default:
> return -EPERM;
> @@ -5100,14 +5106,17 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> if (rc)
> return rc;
>
> - io_parms.pid = current->tgid;
> - io_parms.tcon = tcon;
> - io_parms.length = sizeof(pdev);
> - iov[1].iov_base = &pdev;
> - iov[1].iov_len = sizeof(pdev);
> + if (pdev_len > 0) {
> + io_parms.pid = current->tgid;
> + io_parms.tcon = tcon;
> + io_parms.length = pdev_len;
> + iov[1].iov_base = &pdev;
> + iov[1].iov_len = pdev_len;
> +
> + rc = server->ops->sync_write(xid, &fid, &io_parms,
> + &bytes_written, iov, 1);
> + }
>
> - rc = server->ops->sync_write(xid, &fid, &io_parms,
> - &bytes_written, iov, 1);
> server->ops->close(xid, tcon, &fid);
> return rc;
> }
> @@ -5149,7 +5158,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
> /*
> * Check if mounted with mount parm 'sfu' mount parm.
> * SFU emulation should work with all servers, but only
> - * supports block and char device (no socket & fifo),
> + * supports block and char device, socket & fifo,
> * and was used by default in earlier versions of Windows
> */
> if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> --
> 2.20.1
>
How did you find the format of the FIFO and SOCK file types? I
couldn't find any references to those so added two new types to allow
current Linux to be able to create these (especially since they are
opaque to the server and thus low risk).
> + case S_IFSOCK:
> - strscpy(pdev.type, "LnxSOCK");
> + /* SFU socket is system file with one zero byte */
> + pdev_len = 1;
> + pdev.type[0] = '\0';
> break;
> case S_IFIFO:
> - strscpy(pdev.type, "LnxFIFO");
> + /* SFU fifo is system file which is empty */
> + pdev_len = 0;
My worry about the suggested change above is that it is possible that
we could accidentally match to an empty file. We intentionally added
the two new dev.type fields for these to avoid collisions with other
things (and since they are Linux specific). It seems risky to have an
empty file with the system attribute marked as a FIFO, and similarly a
file with one byte null as Socket. Since this is for only the Linux
client to recognize, I wanted to do something safe for those file
types less likely to be confusing (ie strings for Socket and FIFO that
were similar in length and format to the other special files seemed
intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
file to reduce confusion ie the tags for those two start with "Lnx" -
ie "something used for Linux client" not related to the original
Interix (those begin with "Intx").
Note that in the long run we hope to use reparse points by default in
more servers to store special files like this but there are a few
cases for unusual workloads that need special file support that would
have to use sfu still. The newer reparse tags that Windows uses "WSL"
have the advantage that they require fewer roundtrips to query (since
the file type is in the reparse tag).
Also noticed an interesting problem when mounted with "sfu" -
"smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
that expected for a FIFO?
On Fri, Sep 13, 2024 at 3:07 PM Pali Rohár <pali@kernel.org> wrote:
>
> On Thursday 12 September 2024 14:05:47 Pali Rohár wrote:
> > SFU-style fifo is empty file with system attribute set. This format is used
> > by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
> > (which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
> >
> > SFU-style socket is file which has system attribute set and file content is
> > one zero byte. This format was introduced in Interix 3.0 subsystem, as part
> > of the Microsoft SFU 3.0 and is used also by all later versions. Previous
> > versions had no UNIX domain socket support.
> >
> > Currently when sfu mount option is specified then CIFS creates fifo and
> > socket special files with some strange LnxSOCK or LnxFIFO content which is
> > not compatible with Microsoft SFU and neither recognized by other SMB
> > implementations which have some SFU support, including older Linux cifs
> > implementations.
> >
> > So when sfu mount option is specified, create all fifo and socket special
> > files compatible with SFU format to achieve SFU interop, as it is expected
> > by sfu mount option.
> >
> > Signed-off-by: Pali Rohár <pali@kernel.org>
>
> Fixes: 72bc63f5e23a ("smb3: fix creating FIFOs when mounting with "sfu" mount option")
> Fixes: 518549c120e6 ("cifs: fix creating sockets when using sfu mount options")
>
> I located commits which introduced those strange LnxSOCK or LnxFIFO
> types which are not compatible with SFU. I would suggest to add those
> two Fixes: tags into commit message for reference.
>
> > ---
> > fs/smb/client/cifssmb.c | 8 ++++----
> > fs/smb/client/smb1ops.c | 2 +-
> > fs/smb/client/smb2ops.c | 29 +++++++++++++++++++----------
> > 3 files changed, 24 insertions(+), 15 deletions(-)
> >
> > diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> > index cfae2e918209..0ffc45aa5e2c 100644
> > --- a/fs/smb/client/cifssmb.c
> > +++ b/fs/smb/client/cifssmb.c
> > @@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
> > pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
> > pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
> > pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
> > - /* set file as system file if special file such
> > - as fifo and server expecting SFU style and
> > + /* set file as system file if special file such as fifo,
> > + * socket, char or block and server expecting SFU style and
> > no Unix extensions */
> >
> > if (create_options & CREATE_OPTION_SPECIAL)
> > @@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
> > req->AllocationSize = 0;
> >
> > /*
> > - * Set file as system file if special file such as fifo and server
> > - * expecting SFU style and no Unix extensions.
> > + * Set file as system file if special file such as fifo, socket, char
> > + * or block and server expecting SFU style and no Unix extensions.
> > */
> > if (create_options & CREATE_OPTION_SPECIAL)
> > req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
> > diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> > index e1f2feb56f45..e03c91a49650 100644
> > --- a/fs/smb/client/smb1ops.c
> > +++ b/fs/smb/client/smb1ops.c
> > @@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
> > /*
> > * Check if mounted with mount parm 'sfu' mount parm.
> > * SFU emulation should work with all servers, but only
> > - * supports block and char device (no socket & fifo),
> > + * supports block and char device, socket & fifo,
> > * and was used by default in earlier versions of Windows
> > */
> > if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
> > diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> > index 9c2d065d3cc4..9e90672caf60 100644
> > --- a/fs/smb/client/smb2ops.c
> > +++ b/fs/smb/client/smb2ops.c
> > @@ -5066,26 +5066,32 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > struct cifs_fid fid;
> > unsigned int bytes_written;
> > struct win_dev pdev = {};
> > + size_t pdev_len = 0;
> > struct kvec iov[2];
> > __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> > int rc;
> >
> > switch (mode & S_IFMT) {
> > case S_IFCHR:
> > + pdev_len = sizeof(pdev);
> > memcpy(pdev.type, "IntxCHR\0", 8);
> > pdev.major = cpu_to_le64(MAJOR(dev));
> > pdev.minor = cpu_to_le64(MINOR(dev));
> > break;
> > case S_IFBLK:
> > + pdev_len = sizeof(pdev);
> > memcpy(pdev.type, "IntxBLK\0", 8);
> > pdev.major = cpu_to_le64(MAJOR(dev));
> > pdev.minor = cpu_to_le64(MINOR(dev));
> > break;
> > case S_IFSOCK:
> > - strscpy(pdev.type, "LnxSOCK");
> > + /* SFU socket is system file with one zero byte */
> > + pdev_len = 1;
> > + pdev.type[0] = '\0';
> > break;
> > case S_IFIFO:
> > - strscpy(pdev.type, "LnxFIFO");
> > + /* SFU fifo is system file which is empty */
> > + pdev_len = 0;
> > break;
> > default:
> > return -EPERM;
> > @@ -5100,14 +5106,17 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > if (rc)
> > return rc;
> >
> > - io_parms.pid = current->tgid;
> > - io_parms.tcon = tcon;
> > - io_parms.length = sizeof(pdev);
> > - iov[1].iov_base = &pdev;
> > - iov[1].iov_len = sizeof(pdev);
> > + if (pdev_len > 0) {
> > + io_parms.pid = current->tgid;
> > + io_parms.tcon = tcon;
> > + io_parms.length = pdev_len;
> > + iov[1].iov_base = &pdev;
> > + iov[1].iov_len = pdev_len;
> > +
> > + rc = server->ops->sync_write(xid, &fid, &io_parms,
> > + &bytes_written, iov, 1);
> > + }
> >
> > - rc = server->ops->sync_write(xid, &fid, &io_parms,
> > - &bytes_written, iov, 1);
> > server->ops->close(xid, tcon, &fid);
> > return rc;
> > }
> > @@ -5149,7 +5158,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
> > /*
> > * Check if mounted with mount parm 'sfu' mount parm.
> > * SFU emulation should work with all servers, but only
> > - * supports block and char device (no socket & fifo),
> > + * supports block and char device, socket & fifo,
> > * and was used by default in earlier versions of Windows
> > */
> > if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> > --
> > 2.20.1
> >
>
--
Thanks,
Steve
On Friday 13 September 2024 17:14:22 Steve French wrote:
> How did you find the format of the FIFO and SOCK file types? I
For fifo there are multiple sources on internet, but none of them is
normative. Everything is just what people have tried. For example this
old email on samba list:
https://lists.samba.org/archive/linux-cifs-client/2005-May/000856.html
Format of the socket I have figured out by creating it in Interix
subsystem and then dumped content of the file from Win32 subsystem.
Then I checked that it has also same format over older MS NFS server.
It was easier than trying to search for some documentation (which I have
not found).
> couldn't find any references to those so added two new types to allow
> current Linux to be able to create these (especially since they are
> opaque to the server and thus low risk).
I was searching over internet again and now I have found patent
https://patents.google.com/patent/US20090049459 which describe symlink
content:
#define NFS_SPECFILE_LNK_V1 0x014b4e4c78746e49 /* “IntxLNK” */
But does not describe other types.
> > + case S_IFSOCK:
> > - strscpy(pdev.type, "LnxSOCK");
> > + /* SFU socket is system file with one zero byte */
> > + pdev_len = 1;
> > + pdev.type[0] = '\0';
> > break;
> > case S_IFIFO:
> > - strscpy(pdev.type, "LnxFIFO");
> > + /* SFU fifo is system file which is empty */
> > + pdev_len = 0;
>
> My worry about the suggested change above is that it is possible that
> we could accidentally match to an empty file.
I fully understand your concerns, but code in this patch is for creating
new fifos. Not recognizing existing fifos.
Code for recognizing existing fifos (=empty file with system attribute)
was not changed and is in Linux cifs client for a very long time.
And if nobody complained yet then this is probably not an issue.
You can create manually on server empty file, mark it as system and then
Linux cifs client even without these changes would recognize that file
as fifo.
> We intentionally added
> the two new dev.type fields for these to avoid collisions with other
> things (and since they are Linux specific). It seems risky to have an
> empty file with the system attribute marked as a FIFO, and similarly a
> file with one byte null as Socket. Since this is for only the Linux
> client to recognize, I wanted to do something safe for those file
> types less likely to be confusing (ie strings for Socket and FIFO that
> were similar in length and format to the other special files seemed
> intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
> file to reduce confusion ie the tags for those two start with "Lnx" -
> ie "something used for Linux client" not related to the original
> Interix (those begin with "Intx").
I see. Now I understand what are those types (as I have not seen them
before). It is somehow misleading if such "LnxFIFO" and LnxSOCK"
functionality is provided by SFU option, but is incompatible with MS SFU
and also with MS NFS server. And is also incompatible with older Linux
cifs clients (as they do not understand those Lnx types).
> Note that in the long run we hope to use reparse points by default in
> more servers to store special files like this but there are a few
> cases for unusual workloads that need special file support that would
> have to use sfu still. The newer reparse tags that Windows uses "WSL"
> have the advantage that they require fewer roundtrips to query (since
> the file type is in the reparse tag).
Yes, new WSL tags seems to be better. Also SFU mount option is not
activated by default.
> Also noticed an interesting problem when mounted with "sfu" -
> "smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
> that expected for a FIFO?
Reading from fifo sleep reading process until some other process write
data to fifo. This is how fifos are working. You can try it on local
filesystem (e.g. ext4 or tmpfs).
$ mkfifo fifo
$ strace cat fifo
You will see in strace output of cat something like:
...
openat(AT_FDCWD, "fifo", O_RDONLY
And once you write to that fifo by other process (e.g. echo abc > fifo)
then cat will unfreeze and continue:
= 3
fstat(3, {st_mode=S_IFIFO|0644, st_size=0, ...}) = 0
fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = -1 ESPIPE (Neprípustné nastavenie pozície)
mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f17a34bb000
read(3, "abc\n", 131072) = 4
...
> On Fri, Sep 13, 2024 at 3:07 PM Pali Rohár <pali@kernel.org> wrote:
> >
> > On Thursday 12 September 2024 14:05:47 Pali Rohár wrote:
> > > SFU-style fifo is empty file with system attribute set. This format is used
> > > by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
> > > (which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
> > >
> > > SFU-style socket is file which has system attribute set and file content is
> > > one zero byte. This format was introduced in Interix 3.0 subsystem, as part
> > > of the Microsoft SFU 3.0 and is used also by all later versions. Previous
> > > versions had no UNIX domain socket support.
> > >
> > > Currently when sfu mount option is specified then CIFS creates fifo and
> > > socket special files with some strange LnxSOCK or LnxFIFO content which is
> > > not compatible with Microsoft SFU and neither recognized by other SMB
> > > implementations which have some SFU support, including older Linux cifs
> > > implementations.
> > >
> > > So when sfu mount option is specified, create all fifo and socket special
> > > files compatible with SFU format to achieve SFU interop, as it is expected
> > > by sfu mount option.
> > >
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> >
> > Fixes: 72bc63f5e23a ("smb3: fix creating FIFOs when mounting with "sfu" mount option")
> > Fixes: 518549c120e6 ("cifs: fix creating sockets when using sfu mount options")
> >
> > I located commits which introduced those strange LnxSOCK or LnxFIFO
> > types which are not compatible with SFU. I would suggest to add those
> > two Fixes: tags into commit message for reference.
> >
> > > ---
> > > fs/smb/client/cifssmb.c | 8 ++++----
> > > fs/smb/client/smb1ops.c | 2 +-
> > > fs/smb/client/smb2ops.c | 29 +++++++++++++++++++----------
> > > 3 files changed, 24 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> > > index cfae2e918209..0ffc45aa5e2c 100644
> > > --- a/fs/smb/client/cifssmb.c
> > > +++ b/fs/smb/client/cifssmb.c
> > > @@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
> > > pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
> > > pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
> > > pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
> > > - /* set file as system file if special file such
> > > - as fifo and server expecting SFU style and
> > > + /* set file as system file if special file such as fifo,
> > > + * socket, char or block and server expecting SFU style and
> > > no Unix extensions */
> > >
> > > if (create_options & CREATE_OPTION_SPECIAL)
> > > @@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
> > > req->AllocationSize = 0;
> > >
> > > /*
> > > - * Set file as system file if special file such as fifo and server
> > > - * expecting SFU style and no Unix extensions.
> > > + * Set file as system file if special file such as fifo, socket, char
> > > + * or block and server expecting SFU style and no Unix extensions.
> > > */
> > > if (create_options & CREATE_OPTION_SPECIAL)
> > > req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
> > > diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> > > index e1f2feb56f45..e03c91a49650 100644
> > > --- a/fs/smb/client/smb1ops.c
> > > +++ b/fs/smb/client/smb1ops.c
> > > @@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
> > > /*
> > > * Check if mounted with mount parm 'sfu' mount parm.
> > > * SFU emulation should work with all servers, but only
> > > - * supports block and char device (no socket & fifo),
> > > + * supports block and char device, socket & fifo,
> > > * and was used by default in earlier versions of Windows
> > > */
> > > if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
> > > diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> > > index 9c2d065d3cc4..9e90672caf60 100644
> > > --- a/fs/smb/client/smb2ops.c
> > > +++ b/fs/smb/client/smb2ops.c
> > > @@ -5066,26 +5066,32 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > > struct cifs_fid fid;
> > > unsigned int bytes_written;
> > > struct win_dev pdev = {};
> > > + size_t pdev_len = 0;
> > > struct kvec iov[2];
> > > __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> > > int rc;
> > >
> > > switch (mode & S_IFMT) {
> > > case S_IFCHR:
> > > + pdev_len = sizeof(pdev);
> > > memcpy(pdev.type, "IntxCHR\0", 8);
> > > pdev.major = cpu_to_le64(MAJOR(dev));
> > > pdev.minor = cpu_to_le64(MINOR(dev));
> > > break;
> > > case S_IFBLK:
> > > + pdev_len = sizeof(pdev);
> > > memcpy(pdev.type, "IntxBLK\0", 8);
> > > pdev.major = cpu_to_le64(MAJOR(dev));
> > > pdev.minor = cpu_to_le64(MINOR(dev));
> > > break;
> > > case S_IFSOCK:
> > > - strscpy(pdev.type, "LnxSOCK");
> > > + /* SFU socket is system file with one zero byte */
> > > + pdev_len = 1;
> > > + pdev.type[0] = '\0';
> > > break;
> > > case S_IFIFO:
> > > - strscpy(pdev.type, "LnxFIFO");
> > > + /* SFU fifo is system file which is empty */
> > > + pdev_len = 0;
> > > break;
> > > default:
> > > return -EPERM;
> > > @@ -5100,14 +5106,17 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > > if (rc)
> > > return rc;
> > >
> > > - io_parms.pid = current->tgid;
> > > - io_parms.tcon = tcon;
> > > - io_parms.length = sizeof(pdev);
> > > - iov[1].iov_base = &pdev;
> > > - iov[1].iov_len = sizeof(pdev);
> > > + if (pdev_len > 0) {
> > > + io_parms.pid = current->tgid;
> > > + io_parms.tcon = tcon;
> > > + io_parms.length = pdev_len;
> > > + iov[1].iov_base = &pdev;
> > > + iov[1].iov_len = pdev_len;
> > > +
> > > + rc = server->ops->sync_write(xid, &fid, &io_parms,
> > > + &bytes_written, iov, 1);
> > > + }
> > >
> > > - rc = server->ops->sync_write(xid, &fid, &io_parms,
> > > - &bytes_written, iov, 1);
> > > server->ops->close(xid, tcon, &fid);
> > > return rc;
> > > }
> > > @@ -5149,7 +5158,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
> > > /*
> > > * Check if mounted with mount parm 'sfu' mount parm.
> > > * SFU emulation should work with all servers, but only
> > > - * supports block and char device (no socket & fifo),
> > > + * supports block and char device, socket & fifo,
> > > * and was used by default in earlier versions of Windows
> > > */
> > > if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> > > --
> > > 2.20.1
> > >
> >
>
>
> --
> Thanks,
>
> Steve
On Fri, Sep 13, 2024 at 5:42 PM Pali Rohár <pali@kernel.org> wrote:
>
> On Friday 13 September 2024 17:14:22 Steve French wrote:
> > How did you find the format of the FIFO and SOCK file types? I
>
> For fifo there are multiple sources on internet, but none of them is
> normative. Everything is just what people have tried. For example this
> old email on samba list:
> https://lists.samba.org/archive/linux-cifs-client/2005-May/000856.html
>
> Format of the socket I have figured out by creating it in Interix
> subsystem and then dumped content of the file from Win32 subsystem.
> Then I checked that it has also same format over older MS NFS server.
> It was easier than trying to search for some documentation (which I have
> not found).
>
> > couldn't find any references to those so added two new types to allow
> > current Linux to be able to create these (especially since they are
> > opaque to the server and thus low risk).
>
> I was searching over internet again and now I have found patent
> https://patents.google.com/patent/US20090049459 which describe symlink
> content:
>
> #define NFS_SPECFILE_LNK_V1 0x014b4e4c78746e49 /* “IntxLNK” */
>
> But does not describe other types.
>
> > > + case S_IFSOCK:
> > > - strscpy(pdev.type, "LnxSOCK");
> > > + /* SFU socket is system file with one zero byte */
> > > + pdev_len = 1;
> > > + pdev.type[0] = '\0';
> > > break;
> > > case S_IFIFO:
> > > - strscpy(pdev.type, "LnxFIFO");
> > > + /* SFU fifo is system file which is empty */
> > > + pdev_len = 0;
> >
> > My worry about the suggested change above is that it is possible that
> > we could accidentally match to an empty file.
>
> I fully understand your concerns, but code in this patch is for creating
> new fifos. Not recognizing existing fifos.
>
> Code for recognizing existing fifos (=empty file with system attribute)
> was not changed and is in Linux cifs client for a very long time.
<>
> > We intentionally added
> > the two new dev.type fields for these to avoid collisions with other
> > things (and since they are Linux specific). It seems risky to have an
> > empty file with the system attribute marked as a FIFO, and similarly a
> > file with one byte null as Socket. Since this is for only the Linux
> > client to recognize, I wanted to do something safe for those file
> > types less likely to be confusing (ie strings for Socket and FIFO that
> > were similar in length and format to the other special files seemed
> > intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
> > file to reduce confusion ie the tags for those two start with "Lnx" -
> > ie "something used for Linux client" not related to the original
> > Interix (those begin with "Intx").
>
> I see. Now I understand what are those types (as I have not seen them
> before). It is somehow misleading if such "LnxFIFO" and LnxSOCK"
> functionality is provided by SFU option, but is incompatible with MS SFU
> and also with MS NFS server. And is also incompatible with older Linux
> cifs clients (as they do not understand those Lnx types).
I am not as worried about FIFO and SOCK type being recognized by
older servers (since almost every use case for them would be for them
to be seen (only) by the client - e.g. for mounts to servers that
don't implement reparse points yet), and since they are less
common file types I am willing to let them be unrecognized by
old clients (we can tag them for stable if older distros don't have
them), but I am concerned about allowing "current clients" to
create empty files for an unusual purpose which could be
confusing/non-intuitive.
And since this change (at least the one to allow FIFOs to be created with "sfu"
has been in mainline for a year and also since it uses a more intuitive tag
("LnxFIFO") than the empty one used by very old Windows) the only
clients who would have created these would be already using this newer tag
(older Linux clients couldn't have created such files - there seems more
risk of regression with reverting the change than with continuing with
the Linux client specific tag (at least to the one for FIFOs
since that has been in much longer than the socket one which is recent)
Will discuss with others - opinions welcome.
There is an upcoming SMB3.1.1 test event coming up next week (and the annual
Storage Developer Conference too) so I can see if others have opinions one
way or another on whether to move to empty (or 1 byte) files for
creating fifos/sockets
> > Note that in the long run we hope to use reparse points by default in
> > more servers to store special files like this but there are a few
> > cases for unusual workloads that need special file support that would
> > have to use sfu still. The newer reparse tags that Windows uses "WSL"
> > have the advantage that they require fewer roundtrips to query (since
> > the file type is in the reparse tag).
>
> Yes, new WSL tags seems to be better. Also SFU mount option is not
> activated by default.
>
> > Also noticed an interesting problem when mounted with "sfu" -
> > "smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
> > that expected for a FIFO?
>
> Reading from fifo sleep reading process until some other process write
> data to fifo. This is how fifos are working. You can try it on local
> filesystem (e.g. ext4 or tmpfs).
makes sense - thx
On Saturday 14 September 2024 01:21:17 Steve French wrote:
> On Fri, Sep 13, 2024 at 5:42 PM Pali Rohár <pali@kernel.org> wrote:
> >
> > On Friday 13 September 2024 17:14:22 Steve French wrote:
> > > How did you find the format of the FIFO and SOCK file types? I
> >
> > For fifo there are multiple sources on internet, but none of them is
> > normative. Everything is just what people have tried. For example this
> > old email on samba list:
> > https://lists.samba.org/archive/linux-cifs-client/2005-May/000856.html
> >
> > Format of the socket I have figured out by creating it in Interix
> > subsystem and then dumped content of the file from Win32 subsystem.
> > Then I checked that it has also same format over older MS NFS server.
> > It was easier than trying to search for some documentation (which I have
> > not found).
> >
> > > couldn't find any references to those so added two new types to allow
> > > current Linux to be able to create these (especially since they are
> > > opaque to the server and thus low risk).
> >
> > I was searching over internet again and now I have found patent
> > https://patents.google.com/patent/US20090049459 which describe symlink
> > content:
> >
> > #define NFS_SPECFILE_LNK_V1 0x014b4e4c78746e49 /* “IntxLNK” */
> >
> > But does not describe other types.
> >
> > > > + case S_IFSOCK:
> > > > - strscpy(pdev.type, "LnxSOCK");
> > > > + /* SFU socket is system file with one zero byte */
> > > > + pdev_len = 1;
> > > > + pdev.type[0] = '\0';
> > > > break;
> > > > case S_IFIFO:
> > > > - strscpy(pdev.type, "LnxFIFO");
> > > > + /* SFU fifo is system file which is empty */
> > > > + pdev_len = 0;
> > >
> > > My worry about the suggested change above is that it is possible that
> > > we could accidentally match to an empty file.
> >
> > I fully understand your concerns, but code in this patch is for creating
> > new fifos. Not recognizing existing fifos.
> >
> > Code for recognizing existing fifos (=empty file with system attribute)
> > was not changed and is in Linux cifs client for a very long time.
> <>
> > > We intentionally added
> > > the two new dev.type fields for these to avoid collisions with other
> > > things (and since they are Linux specific). It seems risky to have an
> > > empty file with the system attribute marked as a FIFO, and similarly a
> > > file with one byte null as Socket. Since this is for only the Linux
> > > client to recognize, I wanted to do something safe for those file
> > > types less likely to be confusing (ie strings for Socket and FIFO that
> > > were similar in length and format to the other special files seemed
> > > intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
> > > file to reduce confusion ie the tags for those two start with "Lnx" -
> > > ie "something used for Linux client" not related to the original
> > > Interix (those begin with "Intx").
> >
> > I see. Now I understand what are those types (as I have not seen them
> > before). It is somehow misleading if such "LnxFIFO" and LnxSOCK"
> > functionality is provided by SFU option, but is incompatible with MS SFU
> > and also with MS NFS server. And is also incompatible with older Linux
> > cifs clients (as they do not understand those Lnx types).
>
> I am not as worried about FIFO and SOCK type being recognized by
> older servers (since almost every use case for them would be for them
> to be seen (only) by the client - e.g. for mounts to servers that
> don't implement reparse points yet), and since they are less
> common file types I am willing to let them be unrecognized by
> old clients (we can tag them for stable if older distros don't have
> them),
This is quite pity for old clients, to break existing interoperability.
At least I see sfu as an compatibility option either for ecosystem with
old clients, or option where server itself does not support reparse
points.
> but I am concerned about allowing "current clients" to
> create empty files for an unusual purpose which could be
> confusing/non-intuitive.
I understand this concern. I thought that this should not be an issue
because files are created with system attribute which is not common for
normal/ordinary usage (system attribute could be less confusing) and
also because this format, at least for fifo is used and understood by
many SW for about 30 years.
> And since this change (at least the one to allow FIFOs to be created with "sfu"
> has been in mainline for a year and also since it uses a more intuitive tag
> ("LnxFIFO") than the empty one used by very old Windows) the only
> clients who would have created these would be already using this newer tag
> (older Linux clients couldn't have created such files - there seems more
> risk of regression with reverting the change than with continuing with
> the Linux client specific tag (at least to the one for FIFOs
> since that has been in much longer than the socket one which is recent)
This kind of stuff is lot of times used on LTS/stable linux
distributions and new kernel to these users/admins do not have to be
delivered yet. Mostly it takes 2-3 years after release. Look for example
at RHEL cycles.
I'm looking on this from opposite perspective. I see this an regression
in -o sfu option that after upgrading from previous LTS version to new,
-o sfu stopped to be compatible with SFU-style fifos.
But your point is valid. But maybe it is not an issue because users
do not have updated yet to new version?
> Will discuss with others - opinions welcome.
>
> There is an upcoming SMB3.1.1 test event coming up next week (and the annual
> Storage Developer Conference too) so I can see if others have opinions one
> way or another on whether to move to empty (or 1 byte) files for
> creating fifos/sockets
Ok, perfect, let me know then about the result.
> > > Note that in the long run we hope to use reparse points by default in
> > > more servers to store special files like this but there are a few
> > > cases for unusual workloads that need special file support that would
> > > have to use sfu still. The newer reparse tags that Windows uses "WSL"
> > > have the advantage that they require fewer roundtrips to query (since
> > > the file type is in the reparse tag).
> >
> > Yes, new WSL tags seems to be better. Also SFU mount option is not
> > activated by default.
> >
> > > Also noticed an interesting problem when mounted with "sfu" -
> > > "smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
> > > that expected for a FIFO?
> >
> > Reading from fifo sleep reading process until some other process write
> > data to fifo. This is how fifos are working. You can try it on local
> > filesystem (e.g. ext4 or tmpfs).
>
> makes sense - thx
Hello Steve,
I have another argument for the empty system file as fifo over the
file with "LnxFIFO" content.
Now I have figured out that even the latest Windows Server 2022 version
provides interoperability of FIFOs in SFU format with Windows NFS 4.1
Server. So if you configure on Windows Server 2022 one share which is
exported over SMB and also NFS at the same time, and over SMB you create
SFU-style fifo, then Windows NFS4.1 server recognize it and properly
reports nfs4type as NFS4FIFO for NFSv4.1 client.
So this SFU FIFO style is not only for old clients and servers, but
still relevant and useful even for latest Windows Server.
And same applies for named sockets.
For testing this scenario it is enough to use just trial version of
latest Windows Server from:
https://go.microsoft.com/fwlink/p/?linkid=2208182
https://go.microsoft.com/fwlink/p/?Linkid=2195280
For setting NFS4.1 and SMB share named "test" I used these cmd commands:
dism /Online /Enable-Feature /All /FeatureName:ServerForNFS-Infrastructure
md C:\test
icacls C:\test /grant Everyone:(OI)(CI)F /T
nfsshare test=C:\test -o rw unmapped=yes
net share test=C:\test /grant:Everyone,FULL
(for everyone who is going to reproduce this scenario, beware that new
Windows servers use by default powershell, so first launch cmd.exe then
copy+paste those commands)
Pali
On Saturday 14 September 2024 10:17:42 Pali Rohár wrote:
> On Saturday 14 September 2024 01:21:17 Steve French wrote:
> > On Fri, Sep 13, 2024 at 5:42 PM Pali Rohár <pali@kernel.org> wrote:
> > >
> > > On Friday 13 September 2024 17:14:22 Steve French wrote:
> > > > How did you find the format of the FIFO and SOCK file types? I
> > >
> > > For fifo there are multiple sources on internet, but none of them is
> > > normative. Everything is just what people have tried. For example this
> > > old email on samba list:
> > > https://lists.samba.org/archive/linux-cifs-client/2005-May/000856.html
> > >
> > > Format of the socket I have figured out by creating it in Interix
> > > subsystem and then dumped content of the file from Win32 subsystem.
> > > Then I checked that it has also same format over older MS NFS server.
> > > It was easier than trying to search for some documentation (which I have
> > > not found).
> > >
> > > > couldn't find any references to those so added two new types to allow
> > > > current Linux to be able to create these (especially since they are
> > > > opaque to the server and thus low risk).
> > >
> > > I was searching over internet again and now I have found patent
> > > https://patents.google.com/patent/US20090049459 which describe symlink
> > > content:
> > >
> > > #define NFS_SPECFILE_LNK_V1 0x014b4e4c78746e49 /* “IntxLNK” */
> > >
> > > But does not describe other types.
> > >
> > > > > + case S_IFSOCK:
> > > > > - strscpy(pdev.type, "LnxSOCK");
> > > > > + /* SFU socket is system file with one zero byte */
> > > > > + pdev_len = 1;
> > > > > + pdev.type[0] = '\0';
> > > > > break;
> > > > > case S_IFIFO:
> > > > > - strscpy(pdev.type, "LnxFIFO");
> > > > > + /* SFU fifo is system file which is empty */
> > > > > + pdev_len = 0;
> > > >
> > > > My worry about the suggested change above is that it is possible that
> > > > we could accidentally match to an empty file.
> > >
> > > I fully understand your concerns, but code in this patch is for creating
> > > new fifos. Not recognizing existing fifos.
> > >
> > > Code for recognizing existing fifos (=empty file with system attribute)
> > > was not changed and is in Linux cifs client for a very long time.
> > <>
> > > > We intentionally added
> > > > the two new dev.type fields for these to avoid collisions with other
> > > > things (and since they are Linux specific). It seems risky to have an
> > > > empty file with the system attribute marked as a FIFO, and similarly a
> > > > file with one byte null as Socket. Since this is for only the Linux
> > > > client to recognize, I wanted to do something safe for those file
> > > > types less likely to be confusing (ie strings for Socket and FIFO that
> > > > were similar in length and format to the other special files seemed
> > > > intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
> > > > file to reduce confusion ie the tags for those two start with "Lnx" -
> > > > ie "something used for Linux client" not related to the original
> > > > Interix (those begin with "Intx").
> > >
> > > I see. Now I understand what are those types (as I have not seen them
> > > before). It is somehow misleading if such "LnxFIFO" and LnxSOCK"
> > > functionality is provided by SFU option, but is incompatible with MS SFU
> > > and also with MS NFS server. And is also incompatible with older Linux
> > > cifs clients (as they do not understand those Lnx types).
> >
> > I am not as worried about FIFO and SOCK type being recognized by
> > older servers (since almost every use case for them would be for them
> > to be seen (only) by the client - e.g. for mounts to servers that
> > don't implement reparse points yet), and since they are less
> > common file types I am willing to let them be unrecognized by
> > old clients (we can tag them for stable if older distros don't have
> > them),
>
> This is quite pity for old clients, to break existing interoperability.
> At least I see sfu as an compatibility option either for ecosystem with
> old clients, or option where server itself does not support reparse
> points.
>
> > but I am concerned about allowing "current clients" to
> > create empty files for an unusual purpose which could be
> > confusing/non-intuitive.
>
> I understand this concern. I thought that this should not be an issue
> because files are created with system attribute which is not common for
> normal/ordinary usage (system attribute could be less confusing) and
> also because this format, at least for fifo is used and understood by
> many SW for about 30 years.
>
> > And since this change (at least the one to allow FIFOs to be created with "sfu"
> > has been in mainline for a year and also since it uses a more intuitive tag
> > ("LnxFIFO") than the empty one used by very old Windows) the only
> > clients who would have created these would be already using this newer tag
> > (older Linux clients couldn't have created such files - there seems more
> > risk of regression with reverting the change than with continuing with
> > the Linux client specific tag (at least to the one for FIFOs
> > since that has been in much longer than the socket one which is recent)
>
> This kind of stuff is lot of times used on LTS/stable linux
> distributions and new kernel to these users/admins do not have to be
> delivered yet. Mostly it takes 2-3 years after release. Look for example
> at RHEL cycles.
>
> I'm looking on this from opposite perspective. I see this an regression
> in -o sfu option that after upgrading from previous LTS version to new,
> -o sfu stopped to be compatible with SFU-style fifos.
>
> But your point is valid. But maybe it is not an issue because users
> do not have updated yet to new version?
>
> > Will discuss with others - opinions welcome.
> >
> > There is an upcoming SMB3.1.1 test event coming up next week (and the annual
> > Storage Developer Conference too) so I can see if others have opinions one
> > way or another on whether to move to empty (or 1 byte) files for
> > creating fifos/sockets
>
> Ok, perfect, let me know then about the result.
>
> > > > Note that in the long run we hope to use reparse points by default in
> > > > more servers to store special files like this but there are a few
> > > > cases for unusual workloads that need special file support that would
> > > > have to use sfu still. The newer reparse tags that Windows uses "WSL"
> > > > have the advantage that they require fewer roundtrips to query (since
> > > > the file type is in the reparse tag).
> > >
> > > Yes, new WSL tags seems to be better. Also SFU mount option is not
> > > activated by default.
> > >
> > > > Also noticed an interesting problem when mounted with "sfu" -
> > > > "smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
> > > > that expected for a FIFO?
> > >
> > > Reading from fifo sleep reading process until some other process write
> > > data to fifo. This is how fifos are working. You can try it on local
> > > filesystem (e.g. ext4 or tmpfs).
> >
> > makes sense - thx
One other thing which worried me a bit is that I confirmed that an
empty file with the system attribute set was matched as a FIFO file
type (when you mount with "sfu") - this seems risky.
On Fri, Sep 13, 2024 at 5:14 PM Steve French <smfrench@gmail.com> wrote:
>
> How did you find the format of the FIFO and SOCK file types? I
> couldn't find any references to those so added two new types to allow
> current Linux to be able to create these (especially since they are
> opaque to the server and thus low risk).
>
> > + case S_IFSOCK:
> > - strscpy(pdev.type, "LnxSOCK");
> > + /* SFU socket is system file with one zero byte */
> > + pdev_len = 1;
> > + pdev.type[0] = '\0';
> > break;
> > case S_IFIFO:
> > - strscpy(pdev.type, "LnxFIFO");
> > + /* SFU fifo is system file which is empty */
> > + pdev_len = 0;
>
> My worry about the suggested change above is that it is possible that
> we could accidentally match to an empty file. We intentionally added
> the two new dev.type fields for these to avoid collisions with other
> things (and since they are Linux specific). It seems risky to have an
> empty file with the system attribute marked as a FIFO, and similarly a
> file with one byte null as Socket. Since this is for only the Linux
> client to recognize, I wanted to do something safe for those file
> types less likely to be confusing (ie strings for Socket and FIFO that
> were similar in length and format to the other special files seemed
> intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
> file to reduce confusion ie the tags for those two start with "Lnx" -
> ie "something used for Linux client" not related to the original
> Interix (those begin with "Intx").
>
> Note that in the long run we hope to use reparse points by default in
> more servers to store special files like this but there are a few
> cases for unusual workloads that need special file support that would
> have to use sfu still. The newer reparse tags that Windows uses "WSL"
> have the advantage that they require fewer roundtrips to query (since
> the file type is in the reparse tag).
>
> Also noticed an interesting problem when mounted with "sfu" -
> "smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
> that expected for a FIFO?
>
> On Fri, Sep 13, 2024 at 3:07 PM Pali Rohár <pali@kernel.org> wrote:
> >
> > On Thursday 12 September 2024 14:05:47 Pali Rohár wrote:
> > > SFU-style fifo is empty file with system attribute set. This format is used
> > > by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
> > > (which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
> > >
> > > SFU-style socket is file which has system attribute set and file content is
> > > one zero byte. This format was introduced in Interix 3.0 subsystem, as part
> > > of the Microsoft SFU 3.0 and is used also by all later versions. Previous
> > > versions had no UNIX domain socket support.
> > >
> > > Currently when sfu mount option is specified then CIFS creates fifo and
> > > socket special files with some strange LnxSOCK or LnxFIFO content which is
> > > not compatible with Microsoft SFU and neither recognized by other SMB
> > > implementations which have some SFU support, including older Linux cifs
> > > implementations.
> > >
> > > So when sfu mount option is specified, create all fifo and socket special
> > > files compatible with SFU format to achieve SFU interop, as it is expected
> > > by sfu mount option.
> > >
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> >
> > Fixes: 72bc63f5e23a ("smb3: fix creating FIFOs when mounting with "sfu" mount option")
> > Fixes: 518549c120e6 ("cifs: fix creating sockets when using sfu mount options")
> >
> > I located commits which introduced those strange LnxSOCK or LnxFIFO
> > types which are not compatible with SFU. I would suggest to add those
> > two Fixes: tags into commit message for reference.
> >
> > > ---
> > > fs/smb/client/cifssmb.c | 8 ++++----
> > > fs/smb/client/smb1ops.c | 2 +-
> > > fs/smb/client/smb2ops.c | 29 +++++++++++++++++++----------
> > > 3 files changed, 24 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> > > index cfae2e918209..0ffc45aa5e2c 100644
> > > --- a/fs/smb/client/cifssmb.c
> > > +++ b/fs/smb/client/cifssmb.c
> > > @@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
> > > pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
> > > pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
> > > pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
> > > - /* set file as system file if special file such
> > > - as fifo and server expecting SFU style and
> > > + /* set file as system file if special file such as fifo,
> > > + * socket, char or block and server expecting SFU style and
> > > no Unix extensions */
> > >
> > > if (create_options & CREATE_OPTION_SPECIAL)
> > > @@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
> > > req->AllocationSize = 0;
> > >
> > > /*
> > > - * Set file as system file if special file such as fifo and server
> > > - * expecting SFU style and no Unix extensions.
> > > + * Set file as system file if special file such as fifo, socket, char
> > > + * or block and server expecting SFU style and no Unix extensions.
> > > */
> > > if (create_options & CREATE_OPTION_SPECIAL)
> > > req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
> > > diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> > > index e1f2feb56f45..e03c91a49650 100644
> > > --- a/fs/smb/client/smb1ops.c
> > > +++ b/fs/smb/client/smb1ops.c
> > > @@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
> > > /*
> > > * Check if mounted with mount parm 'sfu' mount parm.
> > > * SFU emulation should work with all servers, but only
> > > - * supports block and char device (no socket & fifo),
> > > + * supports block and char device, socket & fifo,
> > > * and was used by default in earlier versions of Windows
> > > */
> > > if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
> > > diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> > > index 9c2d065d3cc4..9e90672caf60 100644
> > > --- a/fs/smb/client/smb2ops.c
> > > +++ b/fs/smb/client/smb2ops.c
> > > @@ -5066,26 +5066,32 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > > struct cifs_fid fid;
> > > unsigned int bytes_written;
> > > struct win_dev pdev = {};
> > > + size_t pdev_len = 0;
> > > struct kvec iov[2];
> > > __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> > > int rc;
> > >
> > > switch (mode & S_IFMT) {
> > > case S_IFCHR:
> > > + pdev_len = sizeof(pdev);
> > > memcpy(pdev.type, "IntxCHR\0", 8);
> > > pdev.major = cpu_to_le64(MAJOR(dev));
> > > pdev.minor = cpu_to_le64(MINOR(dev));
> > > break;
> > > case S_IFBLK:
> > > + pdev_len = sizeof(pdev);
> > > memcpy(pdev.type, "IntxBLK\0", 8);
> > > pdev.major = cpu_to_le64(MAJOR(dev));
> > > pdev.minor = cpu_to_le64(MINOR(dev));
> > > break;
> > > case S_IFSOCK:
> > > - strscpy(pdev.type, "LnxSOCK");
> > > + /* SFU socket is system file with one zero byte */
> > > + pdev_len = 1;
> > > + pdev.type[0] = '\0';
> > > break;
> > > case S_IFIFO:
> > > - strscpy(pdev.type, "LnxFIFO");
> > > + /* SFU fifo is system file which is empty */
> > > + pdev_len = 0;
> > > break;
> > > default:
> > > return -EPERM;
> > > @@ -5100,14 +5106,17 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > > if (rc)
> > > return rc;
> > >
> > > - io_parms.pid = current->tgid;
> > > - io_parms.tcon = tcon;
> > > - io_parms.length = sizeof(pdev);
> > > - iov[1].iov_base = &pdev;
> > > - iov[1].iov_len = sizeof(pdev);
> > > + if (pdev_len > 0) {
> > > + io_parms.pid = current->tgid;
> > > + io_parms.tcon = tcon;
> > > + io_parms.length = pdev_len;
> > > + iov[1].iov_base = &pdev;
> > > + iov[1].iov_len = pdev_len;
> > > +
> > > + rc = server->ops->sync_write(xid, &fid, &io_parms,
> > > + &bytes_written, iov, 1);
> > > + }
> > >
> > > - rc = server->ops->sync_write(xid, &fid, &io_parms,
> > > - &bytes_written, iov, 1);
> > > server->ops->close(xid, tcon, &fid);
> > > return rc;
> > > }
> > > @@ -5149,7 +5158,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
> > > /*
> > > * Check if mounted with mount parm 'sfu' mount parm.
> > > * SFU emulation should work with all servers, but only
> > > - * supports block and char device (no socket & fifo),
> > > + * supports block and char device, socket & fifo,
> > > * and was used by default in earlier versions of Windows
> > > */
> > > if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> > > --
> > > 2.20.1
> > >
> >
>
>
> --
> Thanks,
>
> Steve
--
Thanks,
Steve
Yes, but it was enabled also before this patch series.
Now I have checked that even old Linux 4.19 cifs kernel client detects
empty file with system attribute as fifo. This functionality is there
for a long time. Probably since first cifs/sfu version.
On Friday 13 September 2024 17:33:22 Steve French wrote:
> One other thing which worried me a bit is that I confirmed that an
> empty file with the system attribute set was matched as a FIFO file
> type (when you mount with "sfu") - this seems risky.
>
> On Fri, Sep 13, 2024 at 5:14 PM Steve French <smfrench@gmail.com> wrote:
> >
> > How did you find the format of the FIFO and SOCK file types? I
> > couldn't find any references to those so added two new types to allow
> > current Linux to be able to create these (especially since they are
> > opaque to the server and thus low risk).
> >
> > > + case S_IFSOCK:
> > > - strscpy(pdev.type, "LnxSOCK");
> > > + /* SFU socket is system file with one zero byte */
> > > + pdev_len = 1;
> > > + pdev.type[0] = '\0';
> > > break;
> > > case S_IFIFO:
> > > - strscpy(pdev.type, "LnxFIFO");
> > > + /* SFU fifo is system file which is empty */
> > > + pdev_len = 0;
> >
> > My worry about the suggested change above is that it is possible that
> > we could accidentally match to an empty file. We intentionally added
> > the two new dev.type fields for these to avoid collisions with other
> > things (and since they are Linux specific). It seems risky to have an
> > empty file with the system attribute marked as a FIFO, and similarly a
> > file with one byte null as Socket. Since this is for only the Linux
> > client to recognize, I wanted to do something safe for those file
> > types less likely to be confusing (ie strings for Socket and FIFO that
> > were similar in length and format to the other special files seemed
> > intuitive) and "LnxFIFO" and LnxSOCK" were used as the tags in the
> > file to reduce confusion ie the tags for those two start with "Lnx" -
> > ie "something used for Linux client" not related to the original
> > Interix (those begin with "Intx").
> >
> > Note that in the long run we hope to use reparse points by default in
> > more servers to store special files like this but there are a few
> > cases for unusual workloads that need special file support that would
> > have to use sfu still. The newer reparse tags that Windows uses "WSL"
> > have the advantage that they require fewer roundtrips to query (since
> > the file type is in the reparse tag).
> >
> > Also noticed an interesting problem when mounted with "sfu" -
> > "smbgetinfo filebasicinfo /mnt/fifo1" will hang (in sys_open). Is
> > that expected for a FIFO?
> >
> > On Fri, Sep 13, 2024 at 3:07 PM Pali Rohár <pali@kernel.org> wrote:
> > >
> > > On Thursday 12 September 2024 14:05:47 Pali Rohár wrote:
> > > > SFU-style fifo is empty file with system attribute set. This format is used
> > > > by old Microsoft POSIX subsystem and later also by OpenNT/Interix subsystem
> > > > (which replaced Microsoft POSIX subsystem and is part of Microsoft SFU).
> > > >
> > > > SFU-style socket is file which has system attribute set and file content is
> > > > one zero byte. This format was introduced in Interix 3.0 subsystem, as part
> > > > of the Microsoft SFU 3.0 and is used also by all later versions. Previous
> > > > versions had no UNIX domain socket support.
> > > >
> > > > Currently when sfu mount option is specified then CIFS creates fifo and
> > > > socket special files with some strange LnxSOCK or LnxFIFO content which is
> > > > not compatible with Microsoft SFU and neither recognized by other SMB
> > > > implementations which have some SFU support, including older Linux cifs
> > > > implementations.
> > > >
> > > > So when sfu mount option is specified, create all fifo and socket special
> > > > files compatible with SFU format to achieve SFU interop, as it is expected
> > > > by sfu mount option.
> > > >
> > > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > >
> > > Fixes: 72bc63f5e23a ("smb3: fix creating FIFOs when mounting with "sfu" mount option")
> > > Fixes: 518549c120e6 ("cifs: fix creating sockets when using sfu mount options")
> > >
> > > I located commits which introduced those strange LnxSOCK or LnxFIFO
> > > types which are not compatible with SFU. I would suggest to add those
> > > two Fixes: tags into commit message for reference.
> > >
> > > > ---
> > > > fs/smb/client/cifssmb.c | 8 ++++----
> > > > fs/smb/client/smb1ops.c | 2 +-
> > > > fs/smb/client/smb2ops.c | 29 +++++++++++++++++++----------
> > > > 3 files changed, 24 insertions(+), 15 deletions(-)
> > > >
> > > > diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
> > > > index cfae2e918209..0ffc45aa5e2c 100644
> > > > --- a/fs/smb/client/cifssmb.c
> > > > +++ b/fs/smb/client/cifssmb.c
> > > > @@ -1076,8 +1076,8 @@ SMBLegacyOpen(const unsigned int xid, struct cifs_tcon *tcon,
> > > > pSMB->OpenFlags |= cpu_to_le16(REQ_MORE_INFO);
> > > > pSMB->Mode = cpu_to_le16(access_flags_to_smbopen_mode(access_flags));
> > > > pSMB->Mode |= cpu_to_le16(0x40); /* deny none */
> > > > - /* set file as system file if special file such
> > > > - as fifo and server expecting SFU style and
> > > > + /* set file as system file if special file such as fifo,
> > > > + * socket, char or block and server expecting SFU style and
> > > > no Unix extensions */
> > > >
> > > > if (create_options & CREATE_OPTION_SPECIAL)
> > > > @@ -1193,8 +1193,8 @@ CIFS_open(const unsigned int xid, struct cifs_open_parms *oparms, int *oplock,
> > > > req->AllocationSize = 0;
> > > >
> > > > /*
> > > > - * Set file as system file if special file such as fifo and server
> > > > - * expecting SFU style and no Unix extensions.
> > > > + * Set file as system file if special file such as fifo, socket, char
> > > > + * or block and server expecting SFU style and no Unix extensions.
> > > > */
> > > > if (create_options & CREATE_OPTION_SPECIAL)
> > > > req->FileAttributes = cpu_to_le32(ATTR_SYSTEM);
> > > > diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
> > > > index e1f2feb56f45..e03c91a49650 100644
> > > > --- a/fs/smb/client/smb1ops.c
> > > > +++ b/fs/smb/client/smb1ops.c
> > > > @@ -1078,7 +1078,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
> > > > /*
> > > > * Check if mounted with mount parm 'sfu' mount parm.
> > > > * SFU emulation should work with all servers, but only
> > > > - * supports block and char device (no socket & fifo),
> > > > + * supports block and char device, socket & fifo,
> > > > * and was used by default in earlier versions of Windows
> > > > */
> > > > if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL))
> > > > diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> > > > index 9c2d065d3cc4..9e90672caf60 100644
> > > > --- a/fs/smb/client/smb2ops.c
> > > > +++ b/fs/smb/client/smb2ops.c
> > > > @@ -5066,26 +5066,32 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > > > struct cifs_fid fid;
> > > > unsigned int bytes_written;
> > > > struct win_dev pdev = {};
> > > > + size_t pdev_len = 0;
> > > > struct kvec iov[2];
> > > > __u32 oplock = server->oplocks ? REQ_OPLOCK : 0;
> > > > int rc;
> > > >
> > > > switch (mode & S_IFMT) {
> > > > case S_IFCHR:
> > > > + pdev_len = sizeof(pdev);
> > > > memcpy(pdev.type, "IntxCHR\0", 8);
> > > > pdev.major = cpu_to_le64(MAJOR(dev));
> > > > pdev.minor = cpu_to_le64(MINOR(dev));
> > > > break;
> > > > case S_IFBLK:
> > > > + pdev_len = sizeof(pdev);
> > > > memcpy(pdev.type, "IntxBLK\0", 8);
> > > > pdev.major = cpu_to_le64(MAJOR(dev));
> > > > pdev.minor = cpu_to_le64(MINOR(dev));
> > > > break;
> > > > case S_IFSOCK:
> > > > - strscpy(pdev.type, "LnxSOCK");
> > > > + /* SFU socket is system file with one zero byte */
> > > > + pdev_len = 1;
> > > > + pdev.type[0] = '\0';
> > > > break;
> > > > case S_IFIFO:
> > > > - strscpy(pdev.type, "LnxFIFO");
> > > > + /* SFU fifo is system file which is empty */
> > > > + pdev_len = 0;
> > > > break;
> > > > default:
> > > > return -EPERM;
> > > > @@ -5100,14 +5106,17 @@ static int __cifs_sfu_make_node(unsigned int xid, struct inode *inode,
> > > > if (rc)
> > > > return rc;
> > > >
> > > > - io_parms.pid = current->tgid;
> > > > - io_parms.tcon = tcon;
> > > > - io_parms.length = sizeof(pdev);
> > > > - iov[1].iov_base = &pdev;
> > > > - iov[1].iov_len = sizeof(pdev);
> > > > + if (pdev_len > 0) {
> > > > + io_parms.pid = current->tgid;
> > > > + io_parms.tcon = tcon;
> > > > + io_parms.length = pdev_len;
> > > > + iov[1].iov_base = &pdev;
> > > > + iov[1].iov_len = pdev_len;
> > > > +
> > > > + rc = server->ops->sync_write(xid, &fid, &io_parms,
> > > > + &bytes_written, iov, 1);
> > > > + }
> > > >
> > > > - rc = server->ops->sync_write(xid, &fid, &io_parms,
> > > > - &bytes_written, iov, 1);
> > > > server->ops->close(xid, tcon, &fid);
> > > > return rc;
> > > > }
> > > > @@ -5149,7 +5158,7 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
> > > > /*
> > > > * Check if mounted with mount parm 'sfu' mount parm.
> > > > * SFU emulation should work with all servers, but only
> > > > - * supports block and char device (no socket & fifo),
> > > > + * supports block and char device, socket & fifo,
> > > > * and was used by default in earlier versions of Windows
> > > > */
> > > > if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
> > > > --
> > > > 2.20.1
> > > >
> > >
> >
> >
> > --
> > Thanks,
> >
> > Steve
>
>
>
> --
> Thanks,
>
> Steve
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