This commit adds the on-disk layout header file of composefs.
Signed-off-by: Alexander Larsson <alexl@redhat.com>
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
---
fs/composefs/cfs.h | 242 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 242 insertions(+)
create mode 100644 fs/composefs/cfs.h
diff --git a/fs/composefs/cfs.h b/fs/composefs/cfs.h
new file mode 100644
index 000000000000..8f001fd28d6b
--- /dev/null
+++ b/fs/composefs/cfs.h
@@ -0,0 +1,242 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * composefs
+ *
+ * Copyright (C) 2021 Giuseppe Scrivano
+ * Copyright (C) 2022 Alexander Larsson
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _CFS_H
+#define _CFS_H
+
+#include <asm/byteorder.h>
+#include <crypto/sha2.h>
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/types.h>
+
+#define CFS_VERSION 1
+
+#define CFS_MAGIC 0xc078629aU
+
+#define CFS_MAX_DIR_CHUNK_SIZE 4096
+#define CFS_MAX_XATTRS_SIZE 4096
+
+static inline u16 cfs_u16_to_file(u16 val)
+{
+ return cpu_to_le16(val);
+}
+
+static inline u32 cfs_u32_to_file(u32 val)
+{
+ return cpu_to_le32(val);
+}
+
+static inline u64 cfs_u64_to_file(u64 val)
+{
+ return cpu_to_le64(val);
+}
+
+static inline u16 cfs_u16_from_file(u16 val)
+{
+ return le16_to_cpu(val);
+}
+
+static inline u32 cfs_u32_from_file(u32 val)
+{
+ return le32_to_cpu(val);
+}
+
+static inline u64 cfs_u64_from_file(u64 val)
+{
+ return le64_to_cpu(val);
+}
+
+static inline int cfs_xdigit_value(char c)
+{
+ if (c >= '0' && c <= '9')
+ return c - '0';
+ if (c >= 'A' && c <= 'F')
+ return c - 'A' + 10;
+ if (c >= 'a' && c <= 'f')
+ return c - 'a' + 10;
+ return -1;
+}
+
+static inline int cfs_digest_from_payload(const char *payload,
+ size_t payload_len,
+ u8 digest_out[SHA256_DIGEST_SIZE])
+{
+ const char *p, *end;
+ u8 last_digit = 0;
+ int digit = 0;
+ size_t n_nibbles = 0;
+
+ end = payload + payload_len;
+ for (p = payload; p != end; p++) {
+ /* Skip subdir structure */
+ if (*p == '/')
+ continue;
+
+ /* Break at (and ignore) extension */
+ if (*p == '.')
+ break;
+
+ if (n_nibbles == SHA256_DIGEST_SIZE * 2)
+ return -1; /* Too long */
+
+ digit = cfs_xdigit_value(*p);
+ if (digit == -1)
+ return -1; /* Not hex digit */
+
+ n_nibbles++;
+ if ((n_nibbles % 2) == 0) {
+ digest_out[n_nibbles / 2 - 1] =
+ (last_digit << 4) | digit;
+ }
+ last_digit = digit;
+ }
+
+ if (n_nibbles != SHA256_DIGEST_SIZE * 2)
+ return -1; /* Too short */
+
+ return 0;
+}
+
+struct cfs_vdata_s {
+ u64 off;
+ u32 len;
+} __packed;
+
+struct cfs_header_s {
+ u8 version;
+ u8 unused1;
+ u16 unused2;
+
+ u32 magic;
+ u64 data_offset;
+ u64 root_inode;
+
+ u64 unused3[2];
+} __packed;
+
+enum cfs_inode_flags {
+ CFS_INODE_FLAGS_NONE = 0,
+ CFS_INODE_FLAGS_PAYLOAD = 1 << 0,
+ CFS_INODE_FLAGS_MODE = 1 << 1,
+ CFS_INODE_FLAGS_NLINK = 1 << 2,
+ CFS_INODE_FLAGS_UIDGID = 1 << 3,
+ CFS_INODE_FLAGS_RDEV = 1 << 4,
+ CFS_INODE_FLAGS_TIMES = 1 << 5,
+ CFS_INODE_FLAGS_TIMES_NSEC = 1 << 6,
+ CFS_INODE_FLAGS_LOW_SIZE = 1 << 7, /* Low 32bit of st_size */
+ CFS_INODE_FLAGS_HIGH_SIZE = 1 << 8, /* High 32bit of st_size */
+ CFS_INODE_FLAGS_XATTRS = 1 << 9,
+ CFS_INODE_FLAGS_DIGEST = 1
+ << 10, /* fs-verity sha256 digest of content */
+ CFS_INODE_FLAGS_DIGEST_FROM_PAYLOAD =
+ 1 << 11, /* Compute digest from payload */
+};
+
+#define CFS_INODE_FLAG_CHECK(_flag, _name) \
+ (((_flag) & (CFS_INODE_FLAGS_##_name)) != 0)
+#define CFS_INODE_FLAG_CHECK_SIZE(_flag, _name, _size) \
+ (CFS_INODE_FLAG_CHECK(_flag, _name) ? (_size) : 0)
+
+#define CFS_INODE_DEFAULT_MODE 0100644
+#define CFS_INODE_DEFAULT_NLINK 1
+#define CFS_INODE_DEFAULT_NLINK_DIR 2
+#define CFS_INODE_DEFAULT_UIDGID 0
+#define CFS_INODE_DEFAULT_RDEV 0
+#define CFS_INODE_DEFAULT_TIMES 0
+
+struct cfs_inode_s {
+ u32 flags;
+
+ /* Optional data: (selected by flags) */
+
+ /* This is the size of the type specific data that comes directly after
+ * the inode in the file. Of this type:
+ *
+ * directory: cfs_dir_s
+ * regular file: the backing filename
+ * symlink: the target link
+ *
+ * Canonically payload_length is 0 for empty dir/file/symlink.
+ */
+ u32 payload_length;
+
+ u32 st_mode; /* File type and mode. */
+ u32 st_nlink; /* Number of hard links, only for regular files. */
+ u32 st_uid; /* User ID of owner. */
+ u32 st_gid; /* Group ID of owner. */
+ u32 st_rdev; /* Device ID (if special file). */
+ u64 st_size; /* Size of file, only used for regular files */
+
+ struct cfs_vdata_s xattrs; /* ref to variable data */
+
+ u8 digest[SHA256_DIGEST_SIZE]; /* fs-verity digest */
+
+ struct timespec64 st_mtim; /* Time of last modification. */
+ struct timespec64 st_ctim; /* Time of last status change. */
+};
+
+static inline u32 cfs_inode_encoded_size(u32 flags)
+{
+ return sizeof(u32) /* flags */ +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, PAYLOAD, sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, MODE, sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, NLINK, sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, UIDGID,
+ sizeof(u32) + sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, RDEV, sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, TIMES, sizeof(u64) * 2) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, TIMES_NSEC, sizeof(u32) * 2) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, LOW_SIZE, sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, HIGH_SIZE, sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, XATTRS,
+ sizeof(u64) + sizeof(u32)) +
+ CFS_INODE_FLAG_CHECK_SIZE(flags, DIGEST, SHA256_DIGEST_SIZE);
+}
+
+struct cfs_dentry_s {
+ /* Index of struct cfs_inode_s */
+ u64 inode_index;
+ u8 d_type;
+ u8 name_len;
+ u16 name_offset;
+} __packed;
+
+struct cfs_dir_chunk_s {
+ u16 n_dentries;
+ u16 chunk_size;
+ u64 chunk_offset;
+} __packed;
+
+struct cfs_dir_s {
+ u32 n_chunks;
+ struct cfs_dir_chunk_s chunks[];
+} __packed;
+
+#define cfs_dir_size(_n_chunks) \
+ (sizeof(struct cfs_dir_s) + \
+ (_n_chunks) * sizeof(struct cfs_dir_chunk_s))
+
+/* xattr representation. */
+struct cfs_xattr_element_s {
+ u16 key_length;
+ u16 value_length;
+} __packed;
+
+struct cfs_xattr_header_s {
+ u16 n_attr;
+ struct cfs_xattr_element_s attr[0];
+} __packed;
+
+#define cfs_xattr_header_size(_n_element) \
+ (sizeof(struct cfs_xattr_header_s) + \
+ (_n_element) * sizeof(struct cfs_xattr_element_s))
+
+#endif
--
2.38.1On Mon, Nov 28, 2022 at 12:16:23PM +0100, Alexander Larsson wrote:
> This commit adds the on-disk layout header file of composefs.
>
> Signed-off-by: Alexander Larsson <alexl@redhat.com>
> Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Add Co-Developed-By: Giuseppe ... ?
Full disclosure: I'm not a file system developer but I'll attempt to
help with the review of this series.
> ---
> fs/composefs/cfs.h | 242 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 242 insertions(+)
> create mode 100644 fs/composefs/cfs.h
>
> diff --git a/fs/composefs/cfs.h b/fs/composefs/cfs.h
> new file mode 100644
> index 000000000000..8f001fd28d6b
> --- /dev/null
> +++ b/fs/composefs/cfs.h
> @@ -0,0 +1,242 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * composefs
> + *
> + * Copyright (C) 2021 Giuseppe Scrivano
> + * Copyright (C) 2022 Alexander Larsson
> + *
> + * This file is released under the GPL.
> + */
> +
> +#ifndef _CFS_H
> +#define _CFS_H
> +
> +#include <asm/byteorder.h>
> +#include <crypto/sha2.h>
> +#include <linux/fs.h>
> +#include <linux/stat.h>
> +#include <linux/types.h>
> +
> +#define CFS_VERSION 1
> +
> +#define CFS_MAGIC 0xc078629aU
> +
> +#define CFS_MAX_DIR_CHUNK_SIZE 4096
> +#define CFS_MAX_XATTRS_SIZE 4096
> +
> +static inline u16 cfs_u16_to_file(u16 val)
> +{
> + return cpu_to_le16(val);
> +}
> +
> +static inline u32 cfs_u32_to_file(u32 val)
> +{
> + return cpu_to_le32(val);
> +}
> +
> +static inline u64 cfs_u64_to_file(u64 val)
> +{
> + return cpu_to_le64(val);
> +}
> +
> +static inline u16 cfs_u16_from_file(u16 val)
> +{
> + return le16_to_cpu(val);
> +}
> +
> +static inline u32 cfs_u32_from_file(u32 val)
> +{
> + return le32_to_cpu(val);
> +}
> +
> +static inline u64 cfs_u64_from_file(u64 val)
> +{
> + return le64_to_cpu(val);
> +}
I don't see where the cfs_xxx_{to,from}_file() approach is used in other
filesystems. Instead, move the cpu() functions directly into the code.
> +static inline int cfs_xdigit_value(char c)
> +{
> + if (c >= '0' && c <= '9')
> + return c - '0';
> + if (c >= 'A' && c <= 'F')
> + return c - 'A' + 10;
> + if (c >= 'a' && c <= 'f')
> + return c - 'a' + 10;
> + return -1;
> +}
There's some utilities in lib/hexdump.c that you can use. hex_to_bin()
will convert a single character and hex2bin() will convert a string for
you.
> +static inline int cfs_digest_from_payload(const char *payload,
> + size_t payload_len,
> + u8 digest_out[SHA256_DIGEST_SIZE])
> +{
> + const char *p, *end;
> + u8 last_digit = 0;
> + int digit = 0;
> + size_t n_nibbles = 0;
Put in reverse Christmas tree order.
> +
> + end = payload + payload_len;
> + for (p = payload; p != end; p++) {
> + /* Skip subdir structure */
> + if (*p == '/')
> + continue;
> +
> + /* Break at (and ignore) extension */
> + if (*p == '.')
> + break;
A comment would be helpful in this area that shows what the payload is
expected to be.
> +
> + if (n_nibbles == SHA256_DIGEST_SIZE * 2)
> + return -1; /* Too long */
return -EINVAL; ?
> +
> + digit = cfs_xdigit_value(*p);
> + if (digit == -1)
> + return -1; /* Not hex digit */
-EINVAL here as well
> +
> + n_nibbles++;
> + if ((n_nibbles % 2) == 0) {
> + digest_out[n_nibbles / 2 - 1] =
> + (last_digit << 4) | digit;
> + }
> + last_digit = digit;
> + }
> +
> + if (n_nibbles != SHA256_DIGEST_SIZE * 2)
> + return -1; /* Too short */
-EINVAL here as well
> +
> + return 0;
> +}
> +
> +struct cfs_vdata_s {
> + u64 off;
> + u32 len;
> +} __packed;
> +
> +struct cfs_header_s {
> + u8 version;
> + u8 unused1;
> + u16 unused2;
> +
> + u32 magic;
Should the magic number appear first?
> + u64 data_offset;
> + u64 root_inode;
> +
> + u64 unused3[2];
> +} __packed;
> +
> +enum cfs_inode_flags {
> + CFS_INODE_FLAGS_NONE = 0,
> + CFS_INODE_FLAGS_PAYLOAD = 1 << 0,
> + CFS_INODE_FLAGS_MODE = 1 << 1,
> + CFS_INODE_FLAGS_NLINK = 1 << 2,
> + CFS_INODE_FLAGS_UIDGID = 1 << 3,
> + CFS_INODE_FLAGS_RDEV = 1 << 4,
> + CFS_INODE_FLAGS_TIMES = 1 << 5,
> + CFS_INODE_FLAGS_TIMES_NSEC = 1 << 6,
> + CFS_INODE_FLAGS_LOW_SIZE = 1 << 7, /* Low 32bit of st_size */
> + CFS_INODE_FLAGS_HIGH_SIZE = 1 << 8, /* High 32bit of st_size */
> + CFS_INODE_FLAGS_XATTRS = 1 << 9,
> + CFS_INODE_FLAGS_DIGEST = 1
> + << 10, /* fs-verity sha256 digest of content */
Include << 10 on line above
Brian
On Thu, 2023-01-05 at 10:55 -0500, Brian Masney wrote:
> On Mon, Nov 28, 2022 at 12:16:23PM +0100, Alexander Larsson wrote:
> > This commit adds the on-disk layout header file of composefs.
> >
> > Signed-off-by: Alexander Larsson <alexl@redhat.com>
> > Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
>
> Add Co-Developed-By: Giuseppe ... ?
>
> Full disclosure: I'm not a file system developer but I'll attempt to
> help with the review of this series.
>
Thanks. I did various changes to the github repo based on your review,
here are the outstanding comments:
>
> > +struct cfs_header_s {
> > + u8 version;
> > + u8 unused1;
> > + u16 unused2;
> > +
> > + u32 magic;
>
> Should the magic number appear first?
I don't think so, the version number is essentially part of the full
magic string.
>
>
--
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Alexander Larsson Red Hat,
Inc
alexl@redhat.com alexander.larsson@gmail.com
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