[PATCH] sparse: use force attribute for fmode_t casts

Vasily Averin posted 1 patch 1 week, 2 days ago
fs/notify/fanotify/fanotify_user.c | 4 ++--
fs/open.c                          | 2 +-
fs/proc/base.c                     | 6 +++---
3 files changed, 6 insertions(+), 6 deletions(-)
[PATCH] sparse: use force attribute for fmode_t casts
Posted by Vasily Averin 1 week, 2 days ago
Fixes sparce warnings:
fs/notify/fanotify/fanotify_user.c:267:63: sparse:
 warning: restricted fmode_t degrades to integer
fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
 warning: restricted fmode_t degrades to integer
fs/proc/base.c:2240:25: sparse: warning: cast to restricted fmode_t
fs/proc/base.c:2297:42: sparse: warning: cast from restricted fmode_t
fs/proc/base.c:2394:48: sparse: warning: cast from restricted fmode_t
fs/open.c:1024:21: sparse: warning: restricted fmode_t degrades to integer

Signed-off-by: Vasily Averin <vvs@openvz.org>
---
 fs/notify/fanotify/fanotify_user.c | 4 ++--
 fs/open.c                          | 2 +-
 fs/proc/base.c                     | 6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 9b32b76a9c30..6b058828e412 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -264,7 +264,7 @@ static int create_fd(struct fsnotify_group *group, struct path *path,
 	 * originally opened O_WRONLY.
 	 */
 	new_file = dentry_open(path,
-			       group->fanotify_data.f_flags | FMODE_NONOTIFY,
+			       group->fanotify_data.f_flags | (__force int)FMODE_NONOTIFY,
 			       current_cred());
 	if (IS_ERR(new_file)) {
 		/*
@@ -1348,7 +1348,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	    (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
 		return -EINVAL;
 
-	f_flags = O_RDWR | FMODE_NONOTIFY;
+	f_flags = O_RDWR | (__force int)FMODE_NONOTIFY;
 	if (flags & FAN_CLOEXEC)
 		f_flags |= O_CLOEXEC;
 	if (flags & FAN_NONBLOCK)
diff --git a/fs/open.c b/fs/open.c
index 1315253e0247..b5ff39ccebfd 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1021,7 +1021,7 @@ inline struct open_how build_open_how(int flags, umode_t mode)
 inline int build_open_flags(const struct open_how *how, struct open_flags *op)
 {
 	u64 flags = how->flags;
-	u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
+	u64 strip = (__force u64)FMODE_NONOTIFY | O_CLOEXEC;
 	int lookup_flags = 0;
 	int acc_mode = ACC_MODE(flags);
 
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c1031843cc6a..194b5ac069e7 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2237,7 +2237,7 @@ static struct dentry *
 proc_map_files_instantiate(struct dentry *dentry,
 			   struct task_struct *task, const void *ptr)
 {
-	fmode_t mode = (fmode_t)(unsigned long)ptr;
+	fmode_t mode = (__force fmode_t)(unsigned long)ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
@@ -2294,7 +2294,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 
 	if (vma->vm_file)
 		result = proc_map_files_instantiate(dentry, task,
-				(void *)(unsigned long)vma->vm_file->f_mode);
+				(void *)(__force unsigned long)vma->vm_file->f_mode);
 
 out_no_vma:
 	mmap_read_unlock(mm);
@@ -2391,7 +2391,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 				      buf, len,
 				      proc_map_files_instantiate,
 				      task,
-				      (void *)(unsigned long)p->mode))
+				      (void *)(__force unsigned long)p->mode))
 			break;
 		ctx->pos++;
 	}
-- 
2.31.1
Re: [PATCH] sparse: use force attribute for fmode_t casts
Posted by Christoph Hellwig 6 days, 22 hours ago
Please just use __FMODE_NONOTIFY instead, which might be a bit misnamed,
but was added exactly for this kind of use.

And remember once more:  __force casts are a massive code smell.  Never
add them before thinking hard about them and adding a comment explaining
why they can't be avoided, preferably in a dedicated helper.
[PATCH v2] sparse: fix incorrect fmode_t casts
Posted by Vasily Averin 5 days, 18 hours ago
Fixes sparce warnings:
fs/notify/fanotify/fanotify_user.c:267:63: sparse:
 warning: restricted fmode_t degrades to integer
fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
 warning: restricted fmode_t degrades to integer
fs/proc/base.c:2240:25: sparse: warning: cast to restricted fmode_t
fs/proc/base.c:2297:42: sparse: warning: cast from restricted fmode_t
fs/proc/base.c:2394:48: sparse: warning: cast from restricted fmode_t
fs/open.c:1024:21: sparse: warning: restricted fmode_t degrades to integer

Signed-off-by: Vasily Averin <vvs@openvz.org>
---
v2:
 1) use __FMODE_NONOTIFY instead of FMODE_NONOTIFY
 2) introduced fmode_instantiate_de/encode helpers
      thanks Christoph Hellwig for the hints
---
 fs/notify/fanotify/fanotify_user.c |  4 ++--
 fs/open.c                          |  2 +-
 fs/proc/base.c                     | 21 ++++++++++++++++-----
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 9b32b76a9c30..2bec3b612618 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -264,7 +264,7 @@ static int create_fd(struct fsnotify_group *group, struct path *path,
 	 * originally opened O_WRONLY.
 	 */
 	new_file = dentry_open(path,
-			       group->fanotify_data.f_flags | FMODE_NONOTIFY,
+			       group->fanotify_data.f_flags | __FMODE_NONOTIFY,
 			       current_cred());
 	if (IS_ERR(new_file)) {
 		/*
@@ -1348,7 +1348,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 	    (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
 		return -EINVAL;
 
-	f_flags = O_RDWR | FMODE_NONOTIFY;
+	f_flags = O_RDWR | __FMODE_NONOTIFY;
 	if (flags & FAN_CLOEXEC)
 		f_flags |= O_CLOEXEC;
 	if (flags & FAN_NONBLOCK)
diff --git a/fs/open.c b/fs/open.c
index 1315253e0247..386c52e4c3b1 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1021,7 +1021,7 @@ inline struct open_how build_open_how(int flags, umode_t mode)
 inline int build_open_flags(const struct open_how *how, struct open_flags *op)
 {
 	u64 flags = how->flags;
-	u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
+	u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;
 	int lookup_flags = 0;
 	int acc_mode = ACC_MODE(flags);
 
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c1031843cc6a..b8ed41eb5784 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2233,11 +2233,21 @@ static const struct inode_operations proc_map_files_link_inode_operations = {
 	.setattr	= proc_setattr,
 };
 
+static fmode_t fmode_instantiate_decode(const void *ptr)
+{
+	return (__force fmode_t)(unsigned long)ptr;
+}
+
+static void *fmode_instantiate_encode(fmode_t fmode)
+{
+	return (void *)(__force unsigned long)fmode;
+}
+
 static struct dentry *
 proc_map_files_instantiate(struct dentry *dentry,
 			   struct task_struct *task, const void *ptr)
 {
-	fmode_t mode = (fmode_t)(unsigned long)ptr;
+	fmode_t mode = fmode_instantiate_decode(ptr);
 	struct proc_inode *ei;
 	struct inode *inode;
 
@@ -2292,10 +2302,11 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 	if (!vma)
 		goto out_no_vma;
 
-	if (vma->vm_file)
-		result = proc_map_files_instantiate(dentry, task,
-				(void *)(unsigned long)vma->vm_file->f_mode);
+	if (vma->vm_file) {
+		void *ptr = fmode_instantiate_encode(vma->vm_file->f_mode);
 
+		result = proc_map_files_instantiate(dentry, task, ptr);
+	}
 out_no_vma:
 	mmap_read_unlock(mm);
 out_put_mm:
@@ -2391,7 +2402,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 				      buf, len,
 				      proc_map_files_instantiate,
 				      task,
-				      (void *)(unsigned long)p->mode))
+				      (void *)(__force unsigned long)p->mode))
 			break;
 		ctx->pos++;
 	}
-- 
2.31.1
Re: [PATCH v2] sparse: fix incorrect fmode_t casts
Posted by Christian Brauner 5 days, 14 hours ago
On Wed, May 18, 2022 at 01:49:07PM +0300, Vasily Averin wrote:
> Fixes sparce warnings:
> fs/notify/fanotify/fanotify_user.c:267:63: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/proc/base.c:2240:25: sparse: warning: cast to restricted fmode_t
> fs/proc/base.c:2297:42: sparse: warning: cast from restricted fmode_t
> fs/proc/base.c:2394:48: sparse: warning: cast from restricted fmode_t
> fs/open.c:1024:21: sparse: warning: restricted fmode_t degrades to integer
> 
> Signed-off-by: Vasily Averin <vvs@openvz.org>
> ---

Looks good to me,
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Re: [PATCH v2] sparse: fix incorrect fmode_t casts
Posted by Christoph Hellwig 5 days, 15 hours ago
The fanotify and open.c changes looks fine, but should be split
into one each with a proper subject and description.

For procfs something simpler like the patch below might be a better
option:

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c1031843cc6aa..c07c6b51f0cb9 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2237,13 +2237,13 @@ static struct dentry *
 proc_map_files_instantiate(struct dentry *dentry,
 			   struct task_struct *task, const void *ptr)
 {
-	fmode_t mode = (fmode_t)(unsigned long)ptr;
+	const fmode_t *mode = ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
 	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK |
-				    ((mode & FMODE_READ ) ? S_IRUSR : 0) |
-				    ((mode & FMODE_WRITE) ? S_IWUSR : 0));
+				    ((*mode & FMODE_READ ) ? S_IRUSR : 0) |
+				    ((*mode & FMODE_WRITE) ? S_IWUSR : 0));
 	if (!inode)
 		return ERR_PTR(-ENOENT);
 
@@ -2294,7 +2294,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 
 	if (vma->vm_file)
 		result = proc_map_files_instantiate(dentry, task,
-				(void *)(unsigned long)vma->vm_file->f_mode);
+				&vma->vm_file->f_mode);
 
 out_no_vma:
 	mmap_read_unlock(mm);
@@ -2391,7 +2391,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 				      buf, len,
 				      proc_map_files_instantiate,
 				      task,
-				      (void *)(unsigned long)p->mode))
+				      &p->mode))
 			break;
 		ctx->pos++;
 	}
Re: [PATCH v2] sparse: fix incorrect fmode_t casts
Posted by Jan Kara 5 days, 17 hours ago
On Wed 18-05-22 13:49:07, Vasily Averin wrote:
> Fixes sparce warnings:
> fs/notify/fanotify/fanotify_user.c:267:63: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/proc/base.c:2240:25: sparse: warning: cast to restricted fmode_t
> fs/proc/base.c:2297:42: sparse: warning: cast from restricted fmode_t
> fs/proc/base.c:2394:48: sparse: warning: cast from restricted fmode_t
> fs/open.c:1024:21: sparse: warning: restricted fmode_t degrades to integer
> 
> Signed-off-by: Vasily Averin <vvs@openvz.org>

Feel free to add:

Acked-by: Jan Kara <jack@suse.cz>

for the fanotify bits.

								Honza

> ---
> v2:
>  1) use __FMODE_NONOTIFY instead of FMODE_NONOTIFY
>  2) introduced fmode_instantiate_de/encode helpers
>       thanks Christoph Hellwig for the hints
> ---
>  fs/notify/fanotify/fanotify_user.c |  4 ++--
>  fs/open.c                          |  2 +-
>  fs/proc/base.c                     | 21 ++++++++++++++++-----
>  3 files changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 9b32b76a9c30..2bec3b612618 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -264,7 +264,7 @@ static int create_fd(struct fsnotify_group *group, struct path *path,
>  	 * originally opened O_WRONLY.
>  	 */
>  	new_file = dentry_open(path,
> -			       group->fanotify_data.f_flags | FMODE_NONOTIFY,
> +			       group->fanotify_data.f_flags | __FMODE_NONOTIFY,
>  			       current_cred());
>  	if (IS_ERR(new_file)) {
>  		/*
> @@ -1348,7 +1348,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
>  	    (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
>  		return -EINVAL;
>  
> -	f_flags = O_RDWR | FMODE_NONOTIFY;
> +	f_flags = O_RDWR | __FMODE_NONOTIFY;
>  	if (flags & FAN_CLOEXEC)
>  		f_flags |= O_CLOEXEC;
>  	if (flags & FAN_NONBLOCK)
> diff --git a/fs/open.c b/fs/open.c
> index 1315253e0247..386c52e4c3b1 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -1021,7 +1021,7 @@ inline struct open_how build_open_how(int flags, umode_t mode)
>  inline int build_open_flags(const struct open_how *how, struct open_flags *op)
>  {
>  	u64 flags = how->flags;
> -	u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
> +	u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;
>  	int lookup_flags = 0;
>  	int acc_mode = ACC_MODE(flags);
>  
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index c1031843cc6a..b8ed41eb5784 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2233,11 +2233,21 @@ static const struct inode_operations proc_map_files_link_inode_operations = {
>  	.setattr	= proc_setattr,
>  };
>  
> +static fmode_t fmode_instantiate_decode(const void *ptr)
> +{
> +	return (__force fmode_t)(unsigned long)ptr;
> +}
> +
> +static void *fmode_instantiate_encode(fmode_t fmode)
> +{
> +	return (void *)(__force unsigned long)fmode;
> +}
> +
>  static struct dentry *
>  proc_map_files_instantiate(struct dentry *dentry,
>  			   struct task_struct *task, const void *ptr)
>  {
> -	fmode_t mode = (fmode_t)(unsigned long)ptr;
> +	fmode_t mode = fmode_instantiate_decode(ptr);
>  	struct proc_inode *ei;
>  	struct inode *inode;
>  
> @@ -2292,10 +2302,11 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
>  	if (!vma)
>  		goto out_no_vma;
>  
> -	if (vma->vm_file)
> -		result = proc_map_files_instantiate(dentry, task,
> -				(void *)(unsigned long)vma->vm_file->f_mode);
> +	if (vma->vm_file) {
> +		void *ptr = fmode_instantiate_encode(vma->vm_file->f_mode);
>  
> +		result = proc_map_files_instantiate(dentry, task, ptr);
> +	}
>  out_no_vma:
>  	mmap_read_unlock(mm);
>  out_put_mm:
> @@ -2391,7 +2402,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
>  				      buf, len,
>  				      proc_map_files_instantiate,
>  				      task,
> -				      (void *)(unsigned long)p->mode))
> +				      (void *)(__force unsigned long)p->mode))
>  			break;
>  		ctx->pos++;
>  	}
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR
Re: [PATCH] sparse: use force attribute for fmode_t casts
Posted by Christian Brauner 1 week ago
On Sat, May 14, 2022 at 01:22:28PM +0300, Vasily Averin wrote:
> Fixes sparce warnings:
> fs/notify/fanotify/fanotify_user.c:267:63: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/proc/base.c:2240:25: sparse: warning: cast to restricted fmode_t
> fs/proc/base.c:2297:42: sparse: warning: cast from restricted fmode_t
> fs/proc/base.c:2394:48: sparse: warning: cast from restricted fmode_t
> fs/open.c:1024:21: sparse: warning: restricted fmode_t degrades to integer
> 
> Signed-off-by: Vasily Averin <vvs@openvz.org>
> ---
>  fs/notify/fanotify/fanotify_user.c | 4 ++--
>  fs/open.c                          | 2 +-

Looks good to me,
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Re: [PATCH] sparse: use force attribute for fmode_t casts
Posted by Jan Kara 1 week ago
On Sat 14-05-22 13:22:28, Vasily Averin wrote:
> Fixes sparce warnings:
> fs/notify/fanotify/fanotify_user.c:267:63: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/notify/fanotify/fanotify_user.c:1351:28: sparse:
>  warning: restricted fmode_t degrades to integer
> fs/proc/base.c:2240:25: sparse: warning: cast to restricted fmode_t
> fs/proc/base.c:2297:42: sparse: warning: cast from restricted fmode_t
> fs/proc/base.c:2394:48: sparse: warning: cast from restricted fmode_t
> fs/open.c:1024:21: sparse: warning: restricted fmode_t degrades to integer
> 
> Signed-off-by: Vasily Averin <vvs@openvz.org>

Looks good. Feel free to add:

Acked-by: Jan Kara <jack@suse.cz>

for the fsnotify related bits.

								Honza

> ---
>  fs/notify/fanotify/fanotify_user.c | 4 ++--
>  fs/open.c                          | 2 +-
>  fs/proc/base.c                     | 6 +++---
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 9b32b76a9c30..6b058828e412 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -264,7 +264,7 @@ static int create_fd(struct fsnotify_group *group, struct path *path,
>  	 * originally opened O_WRONLY.
>  	 */
>  	new_file = dentry_open(path,
> -			       group->fanotify_data.f_flags | FMODE_NONOTIFY,
> +			       group->fanotify_data.f_flags | (__force int)FMODE_NONOTIFY,
>  			       current_cred());
>  	if (IS_ERR(new_file)) {
>  		/*
> @@ -1348,7 +1348,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
>  	    (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
>  		return -EINVAL;
>  
> -	f_flags = O_RDWR | FMODE_NONOTIFY;
> +	f_flags = O_RDWR | (__force int)FMODE_NONOTIFY;
>  	if (flags & FAN_CLOEXEC)
>  		f_flags |= O_CLOEXEC;
>  	if (flags & FAN_NONBLOCK)
> diff --git a/fs/open.c b/fs/open.c
> index 1315253e0247..b5ff39ccebfd 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -1021,7 +1021,7 @@ inline struct open_how build_open_how(int flags, umode_t mode)
>  inline int build_open_flags(const struct open_how *how, struct open_flags *op)
>  {
>  	u64 flags = how->flags;
> -	u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
> +	u64 strip = (__force u64)FMODE_NONOTIFY | O_CLOEXEC;
>  	int lookup_flags = 0;
>  	int acc_mode = ACC_MODE(flags);
>  
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index c1031843cc6a..194b5ac069e7 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2237,7 +2237,7 @@ static struct dentry *
>  proc_map_files_instantiate(struct dentry *dentry,
>  			   struct task_struct *task, const void *ptr)
>  {
> -	fmode_t mode = (fmode_t)(unsigned long)ptr;
> +	fmode_t mode = (__force fmode_t)(unsigned long)ptr;
>  	struct proc_inode *ei;
>  	struct inode *inode;
>  
> @@ -2294,7 +2294,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
>  
>  	if (vma->vm_file)
>  		result = proc_map_files_instantiate(dentry, task,
> -				(void *)(unsigned long)vma->vm_file->f_mode);
> +				(void *)(__force unsigned long)vma->vm_file->f_mode);
>  
>  out_no_vma:
>  	mmap_read_unlock(mm);
> @@ -2391,7 +2391,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
>  				      buf, len,
>  				      proc_map_files_instantiate,
>  				      task,
> -				      (void *)(unsigned long)p->mode))
> +				      (void *)(__force unsigned long)p->mode))
>  			break;
>  		ctx->pos++;
>  	}
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR