mirror of
https://src.fedoraproject.org/rpms/grub2.git
synced 2024-11-24 14:32:58 +00:00
grub-set-bootflag: Write new env to tmpfile and then rename
Resolves: CVE-2019-14865 Resolves: rhbz#1776580 Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
This commit is contained in:
Javier Martinez Canillas
parent
ce4c8db354
commit
172b494fc6
4 changed files with 187 additions and 1 deletions
|
|
@ -0,0 +1,27 @@
|
|||
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
||||
From: Hans de Goede <hdegoede@redhat.com>
|
||||
Date: Wed, 13 Nov 2019 12:15:43 +0100
|
||||
Subject: [PATCH] grub-set-bootflag: Update comment about running as root
|
||||
through pkexec
|
||||
|
||||
We have stopped using pkexec for grub-set-bootflag, instead it is now
|
||||
installed suid root, update the comment accordingly.
|
||||
|
||||
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
|
||||
---
|
||||
util/grub-set-bootflag.c | 2 +-
|
||||
1 file changed, 1 insertion(+), 1 deletion(-)
|
||||
|
||||
diff --git a/util/grub-set-bootflag.c b/util/grub-set-bootflag.c
|
||||
index 6a79ee67444..65d74ce010f 100644
|
||||
--- a/util/grub-set-bootflag.c
|
||||
+++ b/util/grub-set-bootflag.c
|
||||
@@ -18,7 +18,7 @@
|
||||
*/
|
||||
|
||||
/*
|
||||
- * NOTE this gets run by users as root (through pkexec), so this does not
|
||||
+ * NOTE this gets run by users as root (its suid root), so this does not
|
||||
* use any grub library / util functions to allow for easy auditing.
|
||||
* The grub headers are only included to get certain defines.
|
||||
*/
|
||||
152
0191-grub-set-bootflag-Write-new-env-to-tmpfile-and-then-.patch
Normal file
152
0191-grub-set-bootflag-Write-new-env-to-tmpfile-and-then-.patch
Normal file
|
|
@ -0,0 +1,152 @@
|
|||
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
||||
From: Hans de Goede <hdegoede@redhat.com>
|
||||
Date: Wed, 13 Nov 2019 13:02:01 +0100
|
||||
Subject: [PATCH] grub-set-bootflag: Write new env to tmpfile and then rename
|
||||
|
||||
Make the grubenv writing code in grub-set-bootflag more robust by
|
||||
writing the modified grubenv to a tmpfile first and then renaming the
|
||||
tmpfile over the old grubenv (following symlinks).
|
||||
|
||||
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
|
||||
---
|
||||
util/grub-set-bootflag.c | 87 +++++++++++++++++++++++++++++++++++++++++++-----
|
||||
1 file changed, 78 insertions(+), 9 deletions(-)
|
||||
|
||||
diff --git a/util/grub-set-bootflag.c b/util/grub-set-bootflag.c
|
||||
index 65d74ce010f..d1c5e28862b 100644
|
||||
--- a/util/grub-set-bootflag.c
|
||||
+++ b/util/grub-set-bootflag.c
|
||||
@@ -28,7 +28,9 @@
|
||||
#include <grub/err.h>
|
||||
#include <grub/lib/envblk.h> /* For GRUB_ENVBLK_DEFCFG define */
|
||||
#include <errno.h>
|
||||
+#include <limits.h>
|
||||
#include <stdio.h>
|
||||
+#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <unistd.h>
|
||||
|
||||
@@ -54,8 +56,10 @@ int main(int argc, char *argv[])
|
||||
{
|
||||
/* NOTE buf must be at least the longest bootflag length + 4 bytes */
|
||||
char env[GRUBENV_SIZE + 1], buf[64], *s;
|
||||
+ /* +1 for 0 termination, +6 for "XXXXXX" in tmp filename */
|
||||
+ char env_filename[PATH_MAX + 1], tmp_filename[PATH_MAX + 6 + 1];
|
||||
const char *bootflag;
|
||||
- int i, len, ret;
|
||||
+ int i, fd, len, ret;
|
||||
FILE *f;
|
||||
|
||||
if (argc != 2)
|
||||
@@ -77,7 +81,32 @@ int main(int argc, char *argv[])
|
||||
bootflag = bootflags[i];
|
||||
len = strlen (bootflag);
|
||||
|
||||
- f = fopen (GRUBENV, "r");
|
||||
+ /*
|
||||
+ * Really become root. setuid avoids an user killing us, possibly leaking
|
||||
+ * the tmpfile. setgid avoids the new grubenv's gid being that of the user.
|
||||
+ */
|
||||
+ ret = setuid(0);
|
||||
+ if (ret)
|
||||
+ {
|
||||
+ perror ("Error setuid(0) failed");
|
||||
+ return 1;
|
||||
+ }
|
||||
+
|
||||
+ ret = setgid(0);
|
||||
+ if (ret)
|
||||
+ {
|
||||
+ perror ("Error setgid(0) failed");
|
||||
+ return 1;
|
||||
+ }
|
||||
+
|
||||
+ /* Canonicalize GRUBENV filename, resolving symlinks, etc. */
|
||||
+ if (!realpath(GRUBENV, env_filename))
|
||||
+ {
|
||||
+ perror ("Error canonicalizing " GRUBENV " filename");
|
||||
+ return 1;
|
||||
+ }
|
||||
+
|
||||
+ f = fopen (env_filename, "r");
|
||||
if (!f)
|
||||
{
|
||||
perror ("Error opening " GRUBENV " for reading");
|
||||
@@ -132,30 +161,70 @@ int main(int argc, char *argv[])
|
||||
snprintf(buf, sizeof(buf), "%s=1\n", bootflag);
|
||||
memcpy(s, buf, len + 3);
|
||||
|
||||
- /* "r+", don't truncate so that the diskspace stays reserved */
|
||||
- f = fopen (GRUBENV, "r+");
|
||||
+
|
||||
+ /*
|
||||
+ * Create a tempfile for writing the new env. Use the canonicalized filename
|
||||
+ * for the template so that the tmpfile is in the same dir / on same fs.
|
||||
+ */
|
||||
+ snprintf(tmp_filename, sizeof(tmp_filename), "%sXXXXXX", env_filename);
|
||||
+ fd = mkstemp(tmp_filename);
|
||||
+ if (fd == -1)
|
||||
+ {
|
||||
+ perror ("Creating tmpfile failed");
|
||||
+ return 1;
|
||||
+ }
|
||||
+
|
||||
+ f = fdopen (fd, "w");
|
||||
if (!f)
|
||||
{
|
||||
- perror ("Error opening " GRUBENV " for writing");
|
||||
+ perror ("Error fdopen of tmpfile failed");
|
||||
+ unlink(tmp_filename);
|
||||
return 1;
|
||||
}
|
||||
|
||||
ret = fwrite (env, 1, GRUBENV_SIZE, f);
|
||||
if (ret != GRUBENV_SIZE)
|
||||
{
|
||||
- perror ("Error writing to " GRUBENV);
|
||||
+ perror ("Error writing tmpfile");
|
||||
+ unlink(tmp_filename);
|
||||
return 1;
|
||||
}
|
||||
|
||||
ret = fflush (f);
|
||||
if (ret)
|
||||
{
|
||||
- perror ("Error flushing " GRUBENV);
|
||||
+ perror ("Error flushing tmpfile");
|
||||
+ unlink(tmp_filename);
|
||||
return 1;
|
||||
}
|
||||
|
||||
- fsync (fileno (f));
|
||||
- fclose (f);
|
||||
+ ret = fsync (fileno (f));
|
||||
+ if (ret)
|
||||
+ {
|
||||
+ perror ("Error syncing tmpfile");
|
||||
+ unlink(tmp_filename);
|
||||
+ return 1;
|
||||
+ }
|
||||
+
|
||||
+ ret = fclose (f);
|
||||
+ if (ret)
|
||||
+ {
|
||||
+ perror ("Error closing tmpfile");
|
||||
+ unlink(tmp_filename);
|
||||
+ return 1;
|
||||
+ }
|
||||
+
|
||||
+ /*
|
||||
+ * And finally rename the tmpfile with the new env over the old env, the
|
||||
+ * linux kernel guarantees that this is atomic (from a syscall pov).
|
||||
+ */
|
||||
+ ret = rename(tmp_filename, env_filename);
|
||||
+ if (ret)
|
||||
+ {
|
||||
+ perror ("Error renaming tmpfile to " GRUBENV " failed");
|
||||
+ unlink(tmp_filename);
|
||||
+ return 1;
|
||||
+ }
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -187,3 +187,5 @@ Patch0186: 0186-grub-core-loader-efi-fdt.c-Do-not-copy-random-memory.patch
|
|||
Patch0187: 0187-linux-efi-arm-fdt-break-FDT-extra-allocation-space-o.patch
|
||||
Patch0188: 0188-Don-t-add-a-class-option-to-menu-entries-generated-f.patch
|
||||
Patch0189: 0189-blscfg-Fix-typo-for-gfxpayload-variable-name.patch
|
||||
Patch0190: 0190-grub-set-bootflag-Update-comment-about-running-as-ro.patch
|
||||
Patch0191: 0191-grub-set-bootflag-Write-new-env-to-tmpfile-and-then-.patch
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
Name: grub2
|
||||
Epoch: 1
|
||||
Version: 2.02
|
||||
Release: 101%{?dist}
|
||||
Release: 102%{?dist}
|
||||
Summary: Bootloader with support for Linux, Multiboot and more
|
||||
License: GPLv3+
|
||||
URL: http://www.gnu.org/software/grub/
|
||||
|
|
@ -518,6 +518,11 @@ rm -r /boot/grub2.tmp/ || :
|
|||
%endif
|
||||
|
||||
%changelog
|
||||
* Tue Nov 26 2019 Javier Martinez Canillas <javierm@redhat.com> - 2.02-102
|
||||
- grub-set-bootflag: Write new env to tmpfile and then rename (hdegoede)
|
||||
Resolves: CVE-2019-14865
|
||||
Resolves: rhbz#1776580
|
||||
|
||||
* Wed Oct 16 2019 Javier Martinez Canillas <javierm@redhat.com> - 2.02-101
|
||||
- 99-grub-mkconfig: Also disable BLS usage for Xen Dom0 hosts
|
||||
Resolves: rhbz#1761799
|
||||
|
|
|
|||
Loading…
Reference in a new issue