main: added support for loading IMA custom policies

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The new function ima_setup() loads an IMA custom policy from a file in the
default location '/etc/ima/ima-policy', if present, and writes it to the
path 'ima/policy' in the security filesystem. This function is executed
at early stage in order to avoid that some file operations are not measured
by IMA and it is placed after the initialization of SELinux because IMA
needs the latter (or other security modules) to understand LSM-specific
rules. This feature is enabled by default and can be disabled by providing
the option '--disable-ima' to the configure script.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Acked-by: Gianluca Ramunno <ramunno@polito.it>

diff --git a/Makefile.am b/Makefile.am
index d8155fdac7296231b721603abb23060606867b1d..6d0b51a0903389372e73be322c9870c75ad8f383 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -510,6 +510,7 @@ libsystemd_core_la_SOURCES = \
        src/mount-setup.c \
        src/hostname-setup.c \
        src/selinux-setup.c \
+       src/ima-setup.c \
        src/loopback-setup.c \
        src/kmod-setup.c \
        src/locale-setup.c \

diff --git a/configure.ac b/configure.ac
index fa17e8be267aeb68f7feebd92dfbea72c53d0eed..47a08dda6462f16c74b2dda5266b678bc6cf6b85 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -127,6 +127,19 @@ PKG_CHECK_MODULES(UDEV, [ libudev >= 172 ])
 PKG_CHECK_MODULES(DBUS, [ dbus-1 >= 1.3.2 ])
 PKG_CHECK_MODULES(KMOD, [ libkmod >= 5 ])
 
+have_ima=yes
+AC_ARG_ENABLE([ima], AS_HELP_STRING([--disable-ima],[Disable optional IMA support]),
+                [case "${enableval}" in
+                        yes) have_ima=yes ;;
+                        no) have_ima=no ;;
+                        *) AC_MSG_ERROR(bad value ${enableval} for --disable-ima) ;;
+                esac],
+                [have_ima=yes])
+
+if test "x${have_ima}" != xno ; then
+        AC_DEFINE(HAVE_IMA, 1, [Define if IMA is available])
+fi
+
 have_selinux=no
 AC_ARG_ENABLE(selinux, AS_HELP_STRING([--disable-selinux], [Disable optional SELINUX support]))
 if test "x$enable_selinux" != "xno"; then
@@ -609,6 +622,7 @@ AC_MSG_RESULT([
         tcpwrap:                 ${have_tcpwrap}
         PAM:                     ${have_pam}
         AUDIT:                   ${have_audit}
+        IMA:                     ${have_ima}
         SELinux:                 ${have_selinux}
         XZ:                      ${have_xz}
         ACL:                     ${have_acl}

diff --git a/src/build.h b/src/build.h
index 50cd79dc7cdbe53cd2036384dc571a9c65ff50ce..0619013141aecb62105e43a6f4b457475ae275e2 100644 (file)
--- a/src/build.h
+++ b/src/build.h
@@ -46,6 +46,12 @@
 #define _SELINUX_FEATURE_ "-SELINUX"
 #endif
 
+#ifdef HAVE_IMA
+#define _IMA_FEATURE_ "+IMA"
+#else
+#define _IMA_FEATURE_ "-IMA"
+#endif
+
 #ifdef HAVE_SYSV_COMPAT
 #define _SYSVINIT_FEATURE_ "+SYSVINIT"
 #else
@@ -58,6 +64,6 @@
 #define _LIBCRYPTSETUP_FEATURE_ "-LIBCRYPTSETUP"
 #endif
 
-#define SYSTEMD_FEATURES _PAM_FEATURE_ " " _LIBWRAP_FEATURE_ " " _AUDIT_FEATURE_ " " _SELINUX_FEATURE_ " " _SYSVINIT_FEATURE_ " " _LIBCRYPTSETUP_FEATURE_
+#define SYSTEMD_FEATURES _PAM_FEATURE_ " " _LIBWRAP_FEATURE_ " " _AUDIT_FEATURE_ " " _SELINUX_FEATURE_ " " _IMA_FEATURE_ " " _SYSVINIT_FEATURE_ " " _LIBCRYPTSETUP_FEATURE_
 
 #endif

diff --git a/src/ima-setup.c b/src/ima-setup.c
new file mode 100644 (file)
index 0000000..03e43dc
--- /dev/null
+++ b/src/ima-setup.c
@@ -0,0 +1,115 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+  Copyright (C) 2012 Roberto Sassu - Politecnico di Torino, Italy
+                                     TORSEC group -- http://security.polito.it
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include "ima-setup.h"
+#include "mount-setup.h"
+#include "macro.h"
+#include "util.h"
+#include "log.h"
+#include "label.h"
+
+#define IMA_SECFS_DIR "/sys/kernel/security/ima"
+#define IMA_SECFS_POLICY IMA_SECFS_DIR "/policy"
+#define IMA_POLICY_PATH "/etc/ima/ima-policy"
+
+int ima_setup(void) {
+
+#ifdef HAVE_IMA
+       struct stat st;
+       ssize_t policy_size = 0, written = 0;
+       char *policy;
+       int policyfd = -1, imafd = -1;
+       int result = 0;
+
+#ifndef HAVE_SELINUX
+       /* Mount the securityfs filesystem */
+       mount_setup_early();
+#endif
+
+       if (stat(IMA_POLICY_PATH, &st) < 0)
+               return 0;
+
+       policy_size = st.st_size;
+       if (stat(IMA_SECFS_DIR, &st) < 0) {
+               log_debug("IMA support is disabled in the kernel, ignoring.");
+               return 0;
+       }
+
+       if (stat(IMA_SECFS_POLICY, &st) < 0) {
+               log_error("Another IMA custom policy has already been loaded, "
+                         "ignoring.");
+               return 0;
+       }
+
+       policyfd = open(IMA_POLICY_PATH, O_RDONLY|O_CLOEXEC);
+       if (policyfd < 0) {
+               log_error("Failed to open the IMA custom policy file %s (%m), "
+                         "ignoring.", IMA_POLICY_PATH);
+               return 0;
+       }
+
+       imafd = open(IMA_SECFS_POLICY, O_WRONLY|O_CLOEXEC);
+       if (imafd < 0) {
+               log_error("Failed to open the IMA kernel interface %s (%m), "
+                         "ignoring.", IMA_SECFS_POLICY);
+               goto out;
+       }
+
+       policy = mmap(NULL, policy_size, PROT_READ, MAP_PRIVATE, policyfd, 0);
+       if (policy == MAP_FAILED) {
+               log_error("mmap() failed (%m), freezing");
+               result = -errno;
+               goto out;
+       }
+
+       written = loop_write(imafd, policy, (size_t)policy_size, false);
+       if (written != policy_size) {
+               log_error("Failed to load the IMA custom policy file %s (%m), "
+                         "ignoring.", IMA_POLICY_PATH);
+               goto out_mmap;
+       }
+
+       log_info("Successfully loaded the IMA custom policy %s.",
+                IMA_POLICY_PATH);
+out_mmap:
+       munmap(policy, policy_size);
+out:
+       if (policyfd >= 0)
+                close_nointr_nofail(policyfd);
+       if (imafd >= 0)
+                close_nointr_nofail(imafd);
+       if (result)
+                return result;
+#endif /* HAVE_IMA */
+
+       return 0;
+}

diff --git a/src/ima-setup.h b/src/ima-setup.h
new file mode 100644 (file)
index 0000000..7d677cf
--- /dev/null
+++ b/src/ima-setup.h
@@ -0,0 +1,29 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef fooimasetuphfoo
+#define fooimasetuphfoo
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+  Copyright (C) 2012 Roberto Sassu - Politecnico di Torino, Italy
+                                     TORSEC group -- http://security.polito.it
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+int ima_setup(void);
+
+#endif

diff --git a/src/main.c b/src/main.c
index ed317b44132235a7c4b63e57863813056a0dcd2e..7ae88414a93a74ed7c09791c86646a7c02c8bd25 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -41,6 +41,7 @@
 #include "kmod-setup.h"
 #include "locale-setup.h"
 #include "selinux-setup.h"
+#include "ima-setup.h"
 #include "machine-id-setup.h"
 #include "load-fragment.h"
 #include "fdset.h"
@@ -1203,9 +1204,12 @@ int main(int argc, char *argv[]) {
                 arg_running_as = MANAGER_SYSTEM;
                 log_set_target(detect_container(NULL) > 0 ? LOG_TARGET_CONSOLE : LOG_TARGET_JOURNAL_OR_KMSG);
 
-                if (!is_reexec)
+                if (!is_reexec) {
                         if (selinux_setup(&loaded_policy) < 0)
                                 goto finish;
+                        if (ima_setup() < 0)
+                                goto finish;
+                }
 
                 log_open();