Unverified Commit 042a6068 authored by Askar Safin's avatar Askar Safin Committed by Christian Brauner
Browse files

openat2: don't trigger automounts with RESOLVE_NO_XDEV 

openat2 had a bug: if we pass RESOLVE_NO_XDEV, then openat2
doesn't traverse through automounts, but may still trigger them.
(See the link for full bug report with reproducer.)

This commit fixes this bug.

Link: https://lore.kernel.org/linux-fsdevel/20250817075252.4137628-1-safinaskar@zohomail.com/


Fixes: fddb5d43 ("open: introduce openat2(2) syscall")
Reviewed-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAskar Safin <safinaskar@zohomail.com>
Link: https://lore.kernel.org/20250825181233.2464822-5-safinaskar@zohomail.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 8ded1fde

fs/namei.c

+8 −0
Original line number Diff line number Diff line
@@ -1449,6 +1449,10 @@ static int follow_automount(struct path *path, int *count, unsigned lookup_flags 
	    dentry->d_inode)

		return -EISDIR;



	/* No need to trigger automounts if mountpoint crossing is disabled. */

	if (lookup_flags & LOOKUP_NO_XDEV)

		return -EXDEV;



	if (count && (*count)++ >= MAXSYMLINKS)

		return -ELOOP;
@@ -1472,6 +1476,10 @@ static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 
		/* Allow the filesystem to manage the transit without i_rwsem

		 * being held. */

		if (flags & DCACHE_MANAGE_TRANSIT) {

			if (lookup_flags & LOOKUP_NO_XDEV) {

				ret = -EXDEV;

				break;

			}

			ret = path->dentry->d_op->d_manage(path, false);

			flags = smp_load_acquire(&path->dentry->d_flags);

			if (ret < 0)