Commit 51dfcb07 authored May 09, 2015 by Linus Torvalds

user-namespace

Pull user-namespace fix from Eric Biederman:
 "Eric Windish recently reported a really bug that allows mounting fresh
  copies of proc and sysfs when it really should not be allowed.  The
  code attempted to verify that proc and sysfs were fully visible but
  there is a test missing to ensure that the root of the filesystem is
  visible.  Doh!

  The following patch fixes that.

  This fixes a containment issue that the docker folks are seeing"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  mnt: Fix fs_fully_visible to verify the root directory is visible

parents 9d88f22a 7e96c1b0

fs/namespace.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -3179,6 +3179,12 @@ bool fs_fully_visible(struct file_system_type *type)
		if (mnt->mnt.mnt_sb->s_type != type)
		continue;

		/* This mount is not fully visible if it's root directory
		* is not the root directory of the filesystem.
		*/
		if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root)
		continue;

		/* This mount is not fully visible if there are any child mounts
		* that cover anything except for empty directories.
		*/

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