Commit 020250f3 authored by Dmitry Kadashev's avatar Dmitry Kadashev Committed by Jens Axboe
Browse files

namei: make do_linkat() take struct filename 



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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/io-uring/20210330071700.kpjoyp5zlni7uejm@wittgenstein/


Signed-off-by: default avatarDmitry Kadashev <dkadashev@gmail.com>
Acked-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20210708063447.3556403-8-dkadashev@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8228e2c3

fs/namei.c

+29 −16
Original line number Diff line number Diff line
@@ -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 @@ static int do_linkat(int olddfd, const char __user *oldname, int newdfd, 
		how |= LOOKUP_REVAL;

		goto retry;

	}

out:

out_putpath:

	path_put(&old_path);

out_putnames:

	putname(old);

	putname(new);



	return error;

}
@@ -4432,12 +4444,13 @@ static int do_linkat(int olddfd, const char __user *oldname, int newdfd, 
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);

}



/**