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fs: add file and path permissions helpers

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Add two simple helpers to check permissions on a file and path
respectively and convert over some callers. It simplifies quite a few
codepaths and also reduces the churn in later patches quite a bit.
Christoph also correctly points out that this makes codepaths (e.g.
ioctls) way easier to follow that would otherwise have to do more
complex argument passing than necessary.

Link: https://lore.kernel.org/r/20210121131959.646623-4-christian.brauner@ubuntu.com
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This commit is contained in:
Christian Brauner 2021-01-21 14:19:22 +01:00
parent e6c9a71451
commit 02f92b3868
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
13 changed files with 24 additions and 16 deletions
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6
fs/init.c
View File

@ -49,7 +49,7 @@ int __init init_chdir(const char *filename)
error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
if (error)
return error;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
if (!error)
set_fs_pwd(current->fs, &path);
path_put(&path);
@ -64,7 +64,7 @@ int __init init_chroot(const char *filename)
error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
if (error)
return error;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;
error = -EPERM;
@ -118,7 +118,7 @@ int __init init_eaccess(const char *filename)
error = kern_path(filename, LOOKUP_FOLLOW, &path);
if (error)
return error;
error = inode_permission(d_inode(path.dentry), MAY_ACCESS);
error = path_permission(&path, MAY_ACCESS);
path_put(&path);
return error;
}

2
fs/notify/fanotify/fanotify_user.c
View File

@ -702,7 +702,7 @@ static int fanotify_find_path(int dfd, const char __user *filename,
}
/* you can only watch an inode if you have read permissions on it */
ret = inode_permission(path->dentry->d_inode, MAY_READ);
ret = path_permission(path, MAY_READ);
if (ret) {
path_put(path);
goto out;

2
fs/notify/inotify/inotify_user.c
View File

@ -352,7 +352,7 @@ static int inotify_find_inode(const char __user *dirname, struct path *path,
if (error)
return error;
/* you can only watch an inode if you have read permissions on it */
error = inode_permission(path->dentry->d_inode, MAY_READ);
error = path_permission(path, MAY_READ);
if (error) {
path_put(path);
return error;

6
fs/open.c
View File

@ -492,7 +492,7 @@ retry:
if (error)
goto out;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;
@ -521,7 +521,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
if (!d_can_lookup(f.file->f_path.dentry))
goto out_putf;
error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
if (!error)
set_fs_pwd(current->fs, &f.file->f_path);
out_putf:
@ -540,7 +540,7 @@ retry:
if (error)
goto out;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;

2
fs/udf/file.c
View File

@ -183,7 +183,7 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
long old_block, new_block;
int result;
if (inode_permission(inode, MAY_READ) != 0) {
if (file_permission(filp, MAY_READ) != 0) {
udf_debug("no permission to access inode %lu\n", inode->i_ino);
return -EPERM;
}

2
fs/verity/enable.c
View File

@ -369,7 +369,7 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *uarg)
* has verity enabled, and to stabilize the data being hashed.
*/
err = inode_permission(inode, MAY_WRITE);
err = file_permission(filp, MAY_WRITE);
if (err)
return err;

8
include/linux/fs.h
View File

@ -2812,6 +2812,14 @@ static inline int bmap(struct inode *inode, sector_t *block)
extern int notify_change(struct dentry *, struct iattr *, struct inode **);
extern int inode_permission(struct inode *, int);
extern int generic_permission(struct inode *, int);
static inline int file_permission(struct file *file, int mask)
{
return inode_permission(file_inode(file), mask);
}
static inline int path_permission(const struct path *path, int mask)
{
return inode_permission(d_inode(path->dentry), mask);
}
extern int __check_sticky(struct inode *dir, struct inode *inode);
static inline bool execute_ok(struct inode *inode)

2
kernel/bpf/inode.c
View File

@ -507,7 +507,7 @@ static void *bpf_obj_do_get(const char __user *pathname,
return ERR_PTR(ret);
inode = d_backing_inode(path.dentry);
ret = inode_permission(inode, ACC_MODE(flags));
ret = path_permission(&path, ACC_MODE(flags));
if (ret)
goto out;

2
kernel/sys.c
View File

@ -1848,7 +1848,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
if (!S_ISREG(inode->i_mode) || path_noexec(&exe.file->f_path))
goto exit;
err = inode_permission(inode, MAY_EXEC);
err = file_permission(exe.file, MAY_EXEC);
if (err)
goto exit;

2
mm/madvise.c
View File

@ -540,7 +540,7 @@ static inline bool can_do_pageout(struct vm_area_struct *vma)
* opens a side channel.
*/
return inode_owner_or_capable(file_inode(vma->vm_file)) ||
inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
file_permission(vma->vm_file, MAY_WRITE) == 0;
}
static long madvise_pageout(struct vm_area_struct *vma,

2
mm/memcontrol.c
View File

@ -4899,7 +4899,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
/* the process need read permission on control file */
/* AV: shouldn't we check that it's been opened for read instead? */
ret = inode_permission(file_inode(cfile.file), MAY_READ);
ret = file_permission(cfile.file, MAY_READ);
if (ret < 0)
goto out_put_cfile;

2
mm/mincore.c
View File

@ -167,7 +167,7 @@ static inline bool can_do_mincore(struct vm_area_struct *vma)
* mappings, which opens a side channel.
*/
return inode_owner_or_capable(file_inode(vma->vm_file)) ||
inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
file_permission(vma->vm_file, MAY_WRITE) == 0;
}
static const struct mm_walk_ops mincore_walk_ops = {

2
net/unix/af_unix.c
View File

@ -936,7 +936,7 @@ static struct sock *unix_find_other(struct net *net,
if (err)
goto fail;
inode = d_backing_inode(path.dentry);
err = inode_permission(inode, MAY_WRITE);
err = path_permission(&path, MAY_WRITE);
if (err)
goto put_fail;