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

From: Ludovic Courtès <[email-masked]>
Date: Wed, 26 Jan 2022 12:56:24 +0100

* 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'.

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 <[email-masked]>
+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 <[email-masked]>
 ;;; Copyright © 2015 Andy Wingo <[email-masked]>
-;;; Copyright © 2015, 2021 Ludovic Courtès <[email-masked]>
+;;; Copyright © 2015, 2021-2022 Ludovic Courtès <[email-masked]>
 ;;; Copyright © 2015 Mark H Weaver <[email-masked]>
 ;;; Copyright © 2016 Efraim Flashner <[email-masked]>
 ;;; Copyright © 2017 Huang Ying <[email-masked]>
@@ -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