This is a note to let you know that I've just added the patch titled
userns: Changing any namespace id mappings should require privileges
to the 3.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
userns-changing-any-namespace-id-mappings-should-require-privileges.patch
and it can be found in the queue-3.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 41c21e351e79004dbb4efa4bc14a53a7e0af38c5 Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Date: Sun, 14 Apr 2013 11:44:04 -0700
Subject: userns: Changing any namespace id mappings should require privileges
From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
commit 41c21e351e79004dbb4efa4bc14a53a7e0af38c5 upstream.
Changing uid/gid/projid mappings doesn't change your id within the
namespace; it reconfigures the namespace. Unprivileged programs should
*not* be able to write these files. (We're also checking the privileges
on the wrong task.)
Given the write-once nature of these files and the other security
checks, this is likely impossible to usefully exploit.
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/user_namespace.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -576,10 +576,10 @@ static ssize_t map_write(struct file *fi
if (map->nr_extents != 0)
goto out;
- /* Require the appropriate privilege CAP_SETUID or CAP_SETGID
- * over the user namespace in order to set the id mapping.
+ /*
+ * Adjusting namespace settings requires capabilities on the target.
*/
- if (cap_valid(cap_setid) && !ns_capable(ns, cap_setid))
+ if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
goto out;
/* Get a buffer */
Patches currently in stable-queue which might be from luto@xxxxxxxxxxxxxx are
queue-3.8/userns-check-uid_map-s-opener-s-fsuid-not-the-current-fsuid.patch
queue-3.8/userns-don-t-let-unprivileged-users-trick-privileged-users-into-setting-the-id_map.patch
queue-3.8/userns-changing-any-namespace-id-mappings-should-require-privileges.patch
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