From 2f0a18b499b9b0e1afbdab8a8bb31d38f2acc6d8 Mon Sep 17 00:00:00 2001
From: Jakub Filak <jfilak@redhat.com>
Date: Fri, 17 Apr 2015 16:06:33 +0200
Subject: [ABRT PATCH] ccpp: emulate selinux for creation of compat cores
This issue was discovered by Florian Weimer of Red Hat Product Security.
http://article.gmane.org/gmane.comp.security.selinux/21842
v2: use the _raw interface and do the preparation steps as root
v3: don't fail if SELinux is disabled
https://github.com/abrt/abrt/commit/c4f06d4198658c82550e93bb2617b96022c06cf4#commitcomment-11021276
Signed-off-by: Jakub Filak <jfilak@redhat.com>
---
configure.ac | 1 +
src/hooks/Makefile.am | 4 ++-
src/hooks/abrt-hook-ccpp.c | 85 ++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 86 insertions(+), 4 deletions(-)
diff --git a/configure.ac b/configure.ac
index 9ff616d..6c6d2e8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -106,6 +106,7 @@ PKG_CHECK_MODULES([LIBREPORT_GTK], [libreport-gtk])
PKG_CHECK_MODULES([POLKIT], [polkit-gobject-1])
PKG_CHECK_MODULES([GIO], [gio-2.0])
PKG_CHECK_MODULES([SATYR], [satyr])
+PKG_CHECK_MODULES([LIBSELINUX], [libselinux])
PKG_PROG_PKG_CONFIG
AC_ARG_WITH([systemdsystemunitdir],
diff --git a/src/hooks/Makefile.am b/src/hooks/Makefile.am
index e536089..9a527f4 100644
--- a/src/hooks/Makefile.am
+++ b/src/hooks/Makefile.am
@@ -33,10 +33,12 @@ abrt_hook_ccpp_CPPFLAGS = \
-DDEFAULT_DUMP_DIR_MODE=$(DEFAULT_DUMP_DIR_MODE) \
$(GLIB_CFLAGS) \
$(LIBREPORT_CFLAGS) \
+ $(LIBSELINUX_CFLAGS) \
-D_GNU_SOURCE
abrt_hook_ccpp_LDADD = \
../lib/libabrt.la \
- $(LIBREPORT_LIBS)
+ $(LIBREPORT_LIBS) \
+ $(LIBSELINUX_LIBS)
# abrt-merge-pstoreoops
abrt_merge_pstoreoops_SOURCES = \
diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c
index 81f9349..00ae621 100644
--- a/src/hooks/abrt-hook-ccpp.c
+++ b/src/hooks/abrt-hook-ccpp.c
@@ -20,6 +20,7 @@
*/
#include <sys/utsname.h>
#include "libabrt.h"
+#include <selinux/selinux.h>
#define DUMP_SUID_UNSAFE 1
#define DUMP_SUID_SAFE 2
@@ -286,6 +287,54 @@ static int dump_suid_policy()
return suid_dump_policy;
}
+/* Computes a security context of new file created by the given process with
+ * pid in the given directory represented by file descriptor.
+ *
+ * On errors returns negative number. Returns 0 if the function succeeds and
+ * computes the context and returns positive number and assigns NULL to newcon
+ * if the security context is not needed (SELinux disabled).
+ */
+static int compute_selinux_con_for_new_file(pid_t pid, int dir_fd, security_context_t *newcon)
+{
+ security_context_t srccon;
+ security_context_t dstcon;
+
+ const int r = is_selinux_enabled();
+ if (r == 0)
+ {
+ *newcon = NULL;
+ return 1;
+ }
+ else if (r == -1)
+ {
+ perror_msg("Couldn't get state of SELinux");
+ return -1;
+ }
+ else if (r != 1)
+ error_msg_and_die("Unexpected SELinux return value: %d", r);
+
+
+ if (getpidcon_raw(pid, &srccon) < 0)
+ {
+ perror_msg("getpidcon_raw(%d)", pid);
+ return -1;
+ }
+
+ if (fgetfilecon_raw(dir_fd, &dstcon) < 0)
+ {
+ perror_msg("getfilecon_raw(%s)", user_pwd);
+ return -1;
+ }
+
+ if (security_compute_create_raw(srccon, dstcon, string_to_security_class("file"), newcon) < 0)
+ {
+ perror_msg("security_compute_create_raw(%s, %s, 'file')", srccon, dstcon);
+ return -1;
+ }
+
+ return 0;
+}
+
static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_values)
{
proc_cwd = open_cwd(pid);
@@ -294,6 +343,14 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
errno = 0;
+ /* http://article.gmane.org/gmane.comp.security.selinux/21842 */
+ security_context_t newcon;
+ if (compute_selinux_con_for_new_file(pid, dirfd(proc_cwd), &newcon) < 0)
+ {
+ log_notice("Not going to create a user core due to SELinux errors");
+ return -1;
+ }
+
xsetegid(get_fsgid());
xseteuid(fsuid);
@@ -388,10 +445,25 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
* (However, see the description of the prctl(2) PR_SET_DUMPABLE operation,
* and the description of the /proc/sys/fs/suid_dumpable file in proc(5).)
*/
+
+ /* Set SELinux context like kernel when creating core dump file */
+ if (newcon != NULL && setfscreatecon_raw(newcon) < 0)
+ {
+ perror_msg("setfscreatecon_raw(%s)", newcon);
+ return -1;
+ }
+
struct stat sb;
errno = 0;
/* Do not O_TRUNC: if later checks fail, we do not want to have file already modified here */
int user_core_fd = openat(dirfd(proc_cwd), core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW | g_user_core_flags, 0600); /* kernel makes 0600 too */
+
+ if (newcon != NULL && setfscreatecon_raw(NULL) < 0)
+ {
+ error_msg("setfscreatecon_raw(NULL)");
+ goto user_core_fail;
+ }
+
xsetegid(0);
xseteuid(0);
if (user_core_fd < 0
@@ -404,16 +476,23 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
perror_msg("Can't open '%s' at '%s'", core_basename, user_pwd);
else
perror_msg("'%s' at '%s' is not a regular file with link count 1 owned by UID(%d)", core_basename, user_pwd, fsuid);
- return -1;
+ goto user_core_fail;
}
if (ftruncate(user_core_fd, 0) != 0) {
/* perror first, otherwise unlink may trash errno */
perror_msg("Can't truncate '%s' at '%s' to size 0", core_basename, user_pwd);
- unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
- return -1;
+ goto user_core_fail;
}
return user_core_fd;
+
+user_core_fail:
+ if (user_core_fd >= 0)
+ {
+ close(user_core_fd);
+ unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
+ }
+ return -1;
}
static bool dump_fd_info(const char *dest_filename, char *source_filename, int source_base_ofs, uid_t uid, gid_t gid)
--
1.8.3.1