Commit a941662d authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Luis Henriques

vfs: Ignore unlocked mounts in fs_fully_visible

commit ceeb0e5d upstream.

Limit the mounts fs_fully_visible considers to locked mounts.
Unlocked can always be unmounted so considering them adds hassle
but no security benefit.
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent ceab5a87
......@@ -3064,11 +3064,15 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
continue;
/* This mount is not fully visible if there are any child mounts
* that cover anything except for empty directories.
/* This mount is not fully visible if there are any
* locked child mounts that cover anything except for
* empty directories.
*/
list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
struct inode *inode = child->mnt_mountpoint->d_inode;
/* Only worry about locked mounts */
if (!(mnt->mnt.mnt_flags & MNT_LOCKED))
continue;
if (!S_ISDIR(inode->i_mode))
goto next;
if (inode->i_nlink > 2)
......
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