| Message ID | 1437008817-5643-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/fs/namespace.c b/fs/namespace.c index 3d29b31..e9b5687 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3175,9 +3175,8 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) /* 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) + /* Is the directory permanetly empty? */ + if (!is_empty_dir_inode(inode)) goto next; } /* Preserve the locked attributes */
This is a note to let you know that I have just added a patch titled mnt: Update fs_fully_visible to test for permanently empty directories to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.y-ckt4. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 98b725a2b319fca945afc589a835aa3ff26bd925 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" <ebiederm@xmission.com> Date: Wed, 13 May 2015 20:51:09 -0500 Subject: mnt: Update fs_fully_visible to test for permanently empty directories commit 7236c85e1be51a9e25ba0f6e087a66ca89605a49 upstream. fs_fully_visible attempts to make fresh mounts of proc and sysfs give the mounter no more access to proc and sysfs than if they could have by creating a bind mount. One aspect of proc and sysfs that makes this particularly tricky is that there are other filesystems that typically mount on top of proc and sysfs. As those filesystems are mounted on empty directories in practice it is safe to ignore them. However testing to ensure filesystems are mounted on empty directories has not been something the in kernel data structures have supported so the current test for an empty directory which checks to see if nlink <= 2 is a bit lacking. proc and sysfs have recently been modified to use the new empty_dir infrastructure to create all of their dedicated mount points. Instead of testing for S_ISDIR(inode->i_mode) && i_nlink <= 2 to see if a directory is empty, test for is_empty_dir_inode(inode). That small change guaranteess mounts found on proc and sysfs really are safe to ignore, because the directories are not only empty but nothing can ever be added to them. This guarantees there is nothing to worry about when mounting proc and sysfs. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/namespace.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) -- 1.9.1