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namei: make do_linkat() take struct filename

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Pass in the struct filename pointers instead of the user string, for
uniformity with do_renameat2, do_unlinkat, do_mknodat, etc.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/io-uring/20210330071700.kpjoyp5zlni7uejm@wittgenstein/
Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20210708063447.3556403-8-dkadashev@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Dmitry Kadashev 2021-07-08 13:34:43 +07:00 committed by Jens Axboe
parent 8228e2c313
commit 020250f31c
1 changed files with 29 additions and 16 deletions
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45
fs/namei.c
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@ -2467,7 +2467,7 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
return err;
}
int filename_lookup(int dfd, struct filename *name, unsigned flags,
static int __filename_lookup(int dfd, struct filename *name, unsigned flags,
struct path *path, struct path *root)
{
int retval;
@ -2485,6 +2485,14 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags,
audit_inode(name, path->dentry,
flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0);
restore_nameidata();
return retval;
}
int filename_lookup(int dfd, struct filename *name, unsigned flags,
struct path *path, struct path *root)
{
int retval = __filename_lookup(dfd, name, flags, path, root);
putname(name);
return retval;
}
@ -4361,8 +4369,8 @@ EXPORT_SYMBOL(vfs_link);
* with linux 2.0, and to avoid hard-linking to directories
* and other special files. --ADM
*/
static int do_linkat(int olddfd, const char __user *oldname, int newdfd,
const char __user *newname, int flags)
static int do_linkat(int olddfd, struct filename *old, int newdfd,
struct filename *new, int flags)
{
struct user_namespace *mnt_userns;
struct dentry *new_dentry;
@ -4371,31 +4379,32 @@ static int do_linkat(int olddfd, const char __user *oldname, int newdfd,
int how = 0;
int error;
if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
return -EINVAL;
if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) {
error = -EINVAL;
goto out_putnames;
}
/*
* To use null names we require CAP_DAC_READ_SEARCH
* This ensures that not everyone will be able to create
* handlink using the passed filedescriptor.
*/
if (flags & AT_EMPTY_PATH) {
if (!capable(CAP_DAC_READ_SEARCH))
return -ENOENT;
how = LOOKUP_EMPTY;
if (flags & AT_EMPTY_PATH && !capable(CAP_DAC_READ_SEARCH)) {
error = -ENOENT;
goto out_putnames;
}
if (flags & AT_SYMLINK_FOLLOW)
how |= LOOKUP_FOLLOW;
retry:
error = user_path_at(olddfd, oldname, how, &old_path);
error = __filename_lookup(olddfd, old, how, &old_path, NULL);
if (error)
return error;
goto out_putnames;
new_dentry = user_path_create(newdfd, newname, &new_path,
new_dentry = __filename_create(newdfd, new, &new_path,
(how & LOOKUP_REVAL));
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto out;
goto out_putpath;
error = -EXDEV;
if (old_path.mnt != new_path.mnt)
@ -4423,8 +4432,11 @@ out_dput:
how |= LOOKUP_REVAL;
goto retry;
}
out:
out_putpath:
path_put(&old_path);
out_putnames:
putname(old);
putname(new);
return error;
}
@ -4432,12 +4444,13 @@ out:
SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname, int, flags)
{
return do_linkat(olddfd, oldname, newdfd, newname, flags);
return do_linkat(olddfd, getname_uflags(oldname, flags),
newdfd, getname(newname), flags);
}
SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
{
return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
return do_linkat(AT_FDCWD, getname(oldname), AT_FDCWD, getname(newname), 0);
}
/**