[PATCH] gnu: polkit: Fix CVE-2021-4034.

Ludovic Courtès wrote on 26 Jan 12:56 +0100

Recipients:(address . guix-patches@gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)

Message-ID:20220126115624.31260-1-ludo@gnu.org

* gnu/packages/patches/polkit-CVE-2021-4034.patch: New file.

* gnu/local.mk (dist_patch_DATA): Add it.

* gnu/packages/polkit.scm (polkit-mozjs)[replacement]: New field.

* gnu/packages/polkit.scm (polkit-mozjs/fixed): New variable.

---

gnu/local.mk | 1 +

.../patches/polkit-CVE-2021-4034.patch | 82 +++++++++++++++++++

gnu/packages/polkit.scm | 13 ++-

3 files changed, 95 insertions(+), 1 deletion(-)

create mode 100644 gnu/packages/patches/polkit-CVE-2021-4034.patch

Hi!

We could avoid grafting and instead use 'polkit/fixed' in 'setuid-programs',

but it seems safer and less error-prone to graft.

Thoughts?

Ludo'.

Toggle diff (143 lines)diff --git a/gnu/local.mk b/gnu/local.mk
index dceaa53145..eb07842775 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1645,6 +1645,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/plib-CVE-2011-4620.patch		\
   %D%/packages/patches/plib-CVE-2012-4552.patch		\
   %D%/packages/patches/plotutils-spline-test.patch		\
+  %D%/packages/patches/polkit-CVE-2021-4034.patch		\
   %D%/packages/patches/polkit-configure-elogind.patch		\
   %D%/packages/patches/polkit-use-duktape.patch			\
   %D%/packages/patches/portaudio-audacity-compat.patch		\
diff --git a/gnu/packages/patches/polkit-CVE-2021-4034.patch b/gnu/packages/patches/polkit-CVE-2021-4034.patch
new file mode 100644
index 0000000000..ca766cb3be
--- /dev/null
+++ b/gnu/packages/patches/polkit-CVE-2021-4034.patch
@@ -0,0 +1,82 @@
+Fixes CVE-2021-4034, local privilege escalation with 'pkexec':
+
+  https://www.openwall.com/lists/oss-security/2022/01/25/11
+
+Patch from <https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683>.
+
+From a2bf5c9c83b6ae46cbd5c779d3055bff81ded683 Mon Sep 17 00:00:00 2001
+From: Jan Rybar <jrybar@redhat.com>
+Date: Tue, 25 Jan 2022 17:21:46 +0000
+Subject: [PATCH] pkexec: local privilege escalation (CVE-2021-4034)
+
+---
+ src/programs/pkcheck.c |  5 +++++
+ src/programs/pkexec.c  | 23 ++++++++++++++++++++---
+ 2 files changed, 25 insertions(+), 3 deletions(-)
+
+diff --git a/src/programs/pkcheck.c b/src/programs/pkcheck.c
+index f1bb4e1..768525c 100644
+--- a/src/programs/pkcheck.c
++++ b/src/programs/pkcheck.c
+@@ -363,6 +363,11 @@ main (int argc, char *argv[])
+   local_agent_handle = NULL;
+   ret = 126;
+ 
++  if (argc < 1)
++    {
++      exit(126);
++    }
++
+   /* Disable remote file access from GIO. */
+   setenv ("GIO_USE_VFS", "local", 1);
+ 
+diff --git a/src/programs/pkexec.c b/src/programs/pkexec.c
+index 7698c5c..84e5ef6 100644
+--- a/src/programs/pkexec.c
++++ b/src/programs/pkexec.c
+@@ -488,6 +488,15 @@ main (int argc, char *argv[])
+   pid_t pid_of_caller;
+   gpointer local_agent_handle;
+ 
++
++  /*
++   * If 'pkexec' is called THIS wrong, someone's probably evil-doing. Don't be nice, just bail out.
++   */
++  if (argc<1)
++    {
++      exit(127);
++    }
++
+   ret = 127;
+   authority = NULL;
+   subject = NULL;
+@@ -614,10 +623,10 @@ main (int argc, char *argv[])
+ 
+       path = g_strdup (pwstruct.pw_shell);
+       if (!path)
+-	{
++        {
+           g_printerr ("No shell configured or error retrieving pw_shell\n");
+           goto out;
+-	}
++        }
+       /* If you change this, be sure to change the if (!command_line)
+ 	 case below too */
+       command_line = g_strdup (path);
+@@ -636,7 +645,15 @@ main (int argc, char *argv[])
+           goto out;
+         }
+       g_free (path);
+-      argv[n] = path = s;
++      path = s;
++
++      /* argc<2 and pkexec runs just shell, argv is guaranteed to be null-terminated.
++       * /-less shell shouldn't happen, but let's be defensive and don't write to null-termination
++       */
++      if (argv[n] != NULL)
++      {
++        argv[n] = path;
++      }
+     }
+   if (access (path, F_OK) != 0)
+     {
diff --git a/gnu/packages/polkit.scm b/gnu/packages/polkit.scm
index e4f4b1276f..1ae94be751 100644
--- a/gnu/packages/polkit.scm
+++ b/gnu/packages/polkit.scm
@@ -1,7 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2014 Andreas Enge <andreas@enge.fr>
 ;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
-;;; Copyright © 2015, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2021-2022 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2016 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2017 Huang Ying <huang.ying.caritas@gmail.com>
@@ -54,6 +54,7 @@ (define-public polkit-mozjs
   (package
     (name "polkit")
     (version "0.120")
+    (replacement polkit-mozjs/fixed)
     (source (origin
              (method url-fetch)
              (uri (string-append
@@ -146,6 +147,16 @@ (define-public polkit-mozjs
 for unprivileged applications.")
     (license lgpl2.0+)))
 
+(define-public polkit-mozjs/fixed
+  (package
+    (inherit polkit-mozjs)
+    (version "0.121")
+    (source (origin
+              (inherit (package-source polkit-mozjs))
+              (patches (cons (search-patch "polkit-CVE-2021-4034.patch")
+                             (origin-patches
+                              (package-source polkit-mozjs))))))))
+
 ;;; Variant of polkit built with Duktape, a lighter JavaScript engine compared
 ;;; to mozjs.
 (define-public polkit-duktape

base-commit: 1402c6abe150ced4cbb4fa0721fe7c8796fe2c38
prerequisite-patch-id: 6ecfe5930fe8847a954c16425713d4a6ac515a04
-- 
2.34.0

Ludovic Courtès wrote on 26 Jan 15:40 +0100

control message for bug #53549

Recipients:(address . control@debbugs.gnu.org)

Message-ID:87sftah85x.fsf@gnu.org

tags 53549 + security

quit

Ludovic Courtès wrote on 26 Jan 15:40 +0100

Recipients:(address . control@debbugs.gnu.org)

Message-ID:87r18uh85v.fsf@gnu.org

severity 53549 important

quit

Liliana Marie Prikler wrote on 26 Jan 16:14 +0100

Re: [PATCH] gnu: polkit: Fix CVE-2021-4034.

Recipients:

Message-ID:a5a0a1f49aa4edcae8de8b43789f95937e6c04d8.camel@ist.tugraz.at

Hi Ludo,

Am Mittwoch, dem 26.01.2022 um 12:56 +0100 schrieb Ludovic Courtès:

Toggle quote (18 lines)> * gnu/packages/patches/polkit-CVE-2021-4034.patch: New file.
> * gnu/local.mk (dist_patch_DATA): Add it.
> * gnu/packages/polkit.scm (polkit-mozjs)[replacement]: New field.
> * gnu/packages/polkit.scm (polkit-mozjs/fixed): New variable.
> ---
>  gnu/local.mk                                  |  1 +
>  .../patches/polkit-CVE-2021-4034.patch        | 82
> +++++++++++++++++++
>  gnu/packages/polkit.scm                       | 13 ++-
>  3 files changed, 95 insertions(+), 1 deletion(-)
>  create mode 100644 gnu/packages/patches/polkit-CVE-2021-4034.patch
> 
> Hi!
> 
> We could avoid grafting and instead use 'polkit/fixed' in 'setuid-
> programs', but it seems safer and less error-prone to graft.
> 
> Thoughts?

Given that there is also a duktape variant, a graft is necessary, no? 
On a related note, polit-duktape inherits polkit-mozjs in a way that
does not require adding a separate graft for it, right?  Assuming both
of the above hold, LGTM.

Cheers

Ludovic Courtès wrote on 26 Jan 17:56 +0100

Re: bug#53549: [PATCH] gnu: polkit: Fix CVE-2021-4034.

Recipients:(name . Liliana Marie Prikler)(address . liliana.prikler@ist.tugraz.at)(address . 53549-done@debbugs.gnu.org)

Message-ID:8735lah1ve.fsf_-_@gnu.org

Hi,

Liliana Marie Prikler <liliana.prikler@ist.tugraz.at> skribis:

Toggle quote (24 lines)> Am Mittwoch, dem 26.01.2022 um 12:56 +0100 schrieb Ludovic Courtès:
>> * gnu/packages/patches/polkit-CVE-2021-4034.patch: New file.
>> * gnu/local.mk (dist_patch_DATA): Add it.
>> * gnu/packages/polkit.scm (polkit-mozjs)[replacement]: New field.
>> * gnu/packages/polkit.scm (polkit-mozjs/fixed): New variable.
>> ---
>>  gnu/local.mk                                  |  1 +
>>  .../patches/polkit-CVE-2021-4034.patch        | 82
>> +++++++++++++++++++
>>  gnu/packages/polkit.scm                       | 13 ++-
>>  3 files changed, 95 insertions(+), 1 deletion(-)
>>  create mode 100644 gnu/packages/patches/polkit-CVE-2021-4034.patch
>> 
>> Hi!
>> 
>> We could avoid grafting and instead use 'polkit/fixed' in 'setuid-
>> programs', but it seems safer and less error-prone to graft.
>> 
>> Thoughts?
> Given that there is also a duktape variant, a graft is necessary, no? 
> On a related note, polit-duktape inherits polkit-mozjs in a way that
> does not require adding a separate graft for it, right?  Assuming both
> of the above hold, LGTM.

The duktape variant is defined with ‘package/inherit’ and thus it

automatically gets a replacement with the patch:

Toggle snippet (8 lines)

$ ./pre-inst-env guix build polkit-duktape --no-grafts

/gnu/store/z92ymaf84ij8f37cm1wrkkmgrw2slrym-polkit-duktape-0.120

$ ./pre-inst-env guix build polkit-duktape

/gnu/store/3g55nhkcbc0a4l7b26gxsalxq0rq1cs7-polkit-duktape-0.121

$ guix gc -R $(./pre-inst-env guix build polkit-duktape -d) |grep polkit-CVE

/gnu/store/lxms944bda56ll590dsrkkhc9n2h3xws-polkit-CVE-2021-4034.patch

Pushed as 3993d33d1c0129b1ca6f0fd122fe2bbe48e4f093.

Thanks for taking a look!

Ludo’.

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