From 879669961b11e7f40b518784863a259f735a72bf Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 17 Jun 2011 11:25:59 +0100
Subject: KEYS/DNS: Fix ____call_usermodehelper() to not lose the session
 keyring

____call_usermodehelper() now erases any credentials set by the
subprocess_inf::init() function.  The problem is that commit
17f60a7da150 ("capabilites: allow the application of capability limits
to usermode helpers") creates and commits new credentials with
prepare_kernel_cred() after the call to the init() function.  This wipes
all keyrings after umh_keys_init() is called.

The best way to deal with this is to put the init() call just prior to
the commit_creds() call, and pass the cred pointer to init().  That
means that umh_keys_init() and suchlike can modify the credentials
_before_ they are published and potentially in use by the rest of the
system.

This prevents request_key() from working as it is prevented from passing
the session keyring it set up with the authorisation token to
/sbin/request-key, and so the latter can't assume the authority to
instantiate the key.  This causes the in-kernel DNS resolver to fail
with ENOKEY unconditionally.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Tested-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/exec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'fs')

diff --git a/fs/exec.c b/fs/exec.c
index 97e0d52d72fd..6075a1e727ae 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1996,7 +1996,7 @@ static void wait_for_dump_helpers(struct file *file)
  * is a special value that we use to trap recursive
  * core dumps
  */
-static int umh_pipe_setup(struct subprocess_info *info)
+static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
 {
 	struct file *rp, *wp;
 	struct fdtable *fdt;
-- 
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