83 lines
2.2 KiB
Diff
83 lines
2.2 KiB
Diff
Fixes CVE-2021-4034, local privilege escalation with 'pkexec':
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https://www.openwall.com/lists/oss-security/2022/01/25/11
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Patch from <https://gitlab.freedesktop.org/polkit/polkit/-/commit/a2bf5c9c83b6ae46cbd5c779d3055bff81ded683>.
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From a2bf5c9c83b6ae46cbd5c779d3055bff81ded683 Mon Sep 17 00:00:00 2001
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From: Jan Rybar <jrybar@redhat.com>
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Date: Tue, 25 Jan 2022 17:21:46 +0000
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Subject: [PATCH] pkexec: local privilege escalation (CVE-2021-4034)
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---
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src/programs/pkcheck.c | 5 +++++
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src/programs/pkexec.c | 23 ++++++++++++++++++++---
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2 files changed, 25 insertions(+), 3 deletions(-)
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diff --git a/src/programs/pkcheck.c b/src/programs/pkcheck.c
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index f1bb4e1..768525c 100644
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--- a/src/programs/pkcheck.c
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+++ b/src/programs/pkcheck.c
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@@ -363,6 +363,11 @@ main (int argc, char *argv[])
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local_agent_handle = NULL;
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ret = 126;
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+ if (argc < 1)
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+ {
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+ exit(126);
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+ }
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+
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/* Disable remote file access from GIO. */
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setenv ("GIO_USE_VFS", "local", 1);
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diff --git a/src/programs/pkexec.c b/src/programs/pkexec.c
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index 7698c5c..84e5ef6 100644
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--- a/src/programs/pkexec.c
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+++ b/src/programs/pkexec.c
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@@ -488,6 +488,15 @@ main (int argc, char *argv[])
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pid_t pid_of_caller;
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gpointer local_agent_handle;
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+
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+ /*
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+ * If 'pkexec' is called THIS wrong, someone's probably evil-doing. Don't be nice, just bail out.
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+ */
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+ if (argc<1)
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+ {
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+ exit(127);
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+ }
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+
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ret = 127;
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authority = NULL;
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subject = NULL;
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@@ -614,10 +623,10 @@ main (int argc, char *argv[])
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path = g_strdup (pwstruct.pw_shell);
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if (!path)
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- {
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+ {
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g_printerr ("No shell configured or error retrieving pw_shell\n");
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goto out;
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- }
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+ }
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/* If you change this, be sure to change the if (!command_line)
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case below too */
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command_line = g_strdup (path);
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@@ -636,7 +645,15 @@ main (int argc, char *argv[])
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goto out;
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}
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g_free (path);
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- argv[n] = path = s;
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+ path = s;
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+
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+ /* argc<2 and pkexec runs just shell, argv is guaranteed to be null-terminated.
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+ * /-less shell shouldn't happen, but let's be defensive and don't write to null-termination
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+ */
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+ if (argv[n] != NULL)
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+ {
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+ argv[n] = path;
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+ }
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}
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if (access (path, F_OK) != 0)
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{
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