Unverified Commit 807602d8 authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Christian Brauner
Browse files

vfs: output mount_too_revealing() errors to fscontext 



It makes little sense for fsmount() to output the warning message when
mount_too_revealing() is violated to kmsg. Instead, the warning should
be output (with a "VFS" prefix) to the fscontext log. In addition,
include the same log message for mount_too_revealing() when doing a
regular mount for consistency.

With the newest fsopen()-based mount(8) from util-linux, the error
messages now look like

  # mount -t proc proc /tmp
  mount: /tmp: fsmount() failed: VFS: Mount too revealing.
         dmesg(1) may have more information after failed mount system call.

which could finally result in mount_too_revealing() errors being easier
for users to detect and understand.

Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Link: https://lore.kernel.org/20250806-errorfc-mount-too-revealing-v2-2-534b9b4d45bb@cyphar.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent ad7fe23b

fs/namespace.c

+4 −2
Original line number Diff line number Diff line
@@ -3724,8 +3724,10 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, 
	int error;



	error = security_sb_kern_mount(sb);

	if (!error && mount_too_revealing(sb, &mnt_flags))

	if (!error && mount_too_revealing(sb, &mnt_flags)) {

		errorfcp(fc, "VFS", "Mount too revealing");

		error = -EPERM;

	}



	if (unlikely(error)) {

		fc_drop_locked(fc);
@@ -4441,7 +4443,7 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, 


	ret = -EPERM;

	if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) {

		pr_warn("VFS: Mount too revealing\n");

		errorfcp(fc, "VFS", "Mount too revealing");

		goto err_unlock;

	}