Patchwork [CVE-2012-2123] lucid/natty fcaps: clear the same personality flags as suid when fcaps are used

login
register
mail settings
Submitter Steve Conklin
Date April 24, 2012, 10:03 p.m.
Message ID <4F972329.60400@canonical.com>
Download mbox | patch
Permalink /patch/154766/
State New
Headers show

Comments

Steve Conklin - April 24, 2012, 10:03 p.m.
This is a clean application of an upstream patch. The same fix has
already come from upstream stable for Oneiric and Precise.

-Steve

From c825bb675aea46fe858b58d1d31dccc6bb7c03c1 Mon Sep 17 00:00:00 2001
From: Eric Paris <eparis@redhat.com>
Date: Tue, 17 Apr 2012 16:26:54 -0400
Subject: [PATCH] fcaps: clear the same personality flags as suid when fcaps
 are used

CVE-2012-2123

BugLink: http://bugs.launchpad.net/bugs/987571

If a process increases permissions using fcaps all of the dangerous
personality flags which are cleared for suid apps should also be cleared.
Thus programs given priviledge with fcaps will continue to have address
space
randomization enabled even if the parent tried to disable it to make it
easier to attack.

Signed-off-by: Eric Paris <eparis@redhat.com>
Reviewed-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

(cherry picked from commit d52fc5dde1)
Signed-off-by: Steve Conklin <sconklin@canonical.com>
---
 security/commoncap.c |    5 +++++
 1 file changed, 5 insertions(+)
Tim Gardner - April 25, 2012, 11:59 a.m.

Serge Hallyn - April 25, 2012, 1:06 p.m.
Quoting Steve Conklin (sconklin@canonical.com):
> This is a clean application of an upstream patch. The same fix has
> already come from upstream stable for Oneiric and Precise.
> 
> -Steve
> 
> From c825bb675aea46fe858b58d1d31dccc6bb7c03c1 Mon Sep 17 00:00:00 2001
> From: Eric Paris <eparis@redhat.com>
> Date: Tue, 17 Apr 2012 16:26:54 -0400
> Subject: [PATCH] fcaps: clear the same personality flags as suid when fcaps
>  are used
> 
> CVE-2012-2123
> 
> BugLink: http://bugs.launchpad.net/bugs/987571
> 
> If a process increases permissions using fcaps all of the dangerous
> personality flags which are cleared for suid apps should also be cleared.
> Thus programs given priviledge with fcaps will continue to have address
> space
> randomization enabled even if the parent tried to disable it to make it
> easier to attack.
> 
> Signed-off-by: Eric Paris <eparis@redhat.com>
> Reviewed-by: Serge Hallyn <serge.hallyn@canonical.com>
> Signed-off-by: James Morris <james.l.morris@oracle.com>
> 
> (cherry picked from commit d52fc5dde1)
> Signed-off-by: Steve Conklin <sconklin@canonical.com>
> ---
>  security/commoncap.c |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/security/commoncap.c b/security/commoncap.c
> index 50be79b..5d5f64b 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -512,6 +512,11 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
>  	}
>  skip:
> 
> +	/* if we have fs caps, clear dangerous personality flags */
> +	if (!cap_issubset(new->cap_permitted, old->cap_permitted))
> +		bprm->per_clear |= PER_CLEAR_ON_SETID;

Don't forget this also needed a follow-up patch to #include
<linux/personality.h>.  (upstream commit
51b79bee627d526199b2f6a6bef8ee0c0739b6d1)

> +
> +
>  	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
>  	 * credentials unless they have the appropriate permit
>  	 */
> -- 
> 1.7.9.5
> 
> -- 
> kernel-team mailing list
> kernel-team@lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

Patch

diff --git a/security/commoncap.c b/security/commoncap.c
index 50be79b..5d5f64b 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -512,6 +512,11 @@  int cap_bprm_set_creds(struct linux_binprm *bprm)
 	}
 skip:

+	/* if we have fs caps, clear dangerous personality flags */
+	if (!cap_issubset(new->cap_permitted, old->cap_permitted))
+		bprm->per_clear |= PER_CLEAR_ON_SETID;
+
+
 	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
 	 * credentials unless they have the appropriate permit
 	 */