From 4e48673172b012a06575e4f5b681d3554eded2e2 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com>

Date: Mon, 6 Jan 2020 15:27:23 +0100

Subject: [PATCH] selinux: add trigger for policy reload to refresh internal

 selabel cache

Reload the internal selabel cache automatically on SELinux policy reloads so non pid-1 daemons are participating.

Run the reload function `mac_selinux_reload()` not manually on daemon-reload, but rather pass it as callback to libselinux.

Trigger the callback prior usage of the systemd internal selabel cache by depleting the selinux netlink socket via `avc_netlink_check_nb()`.

Improves: a9dfac21ec85 ("core: reload SELinux label cache on daemon-reload")

Improves: #13363

(cherry picked from commit 61f3e897f13101f29fb8027e8839498a469ad58e)

Related: #1888912

---

 src/basic/selinux-util.c | 23 +++++++++++++++++++----

 src/basic/selinux-util.h |  1 -

 src/core/main.c          |  2 --

 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/basic/selinux-util.c b/src/basic/selinux-util.c

index a078ce23ef..bfe3d015aa 100644

--- a/src/basic/selinux-util.c

+++ b/src/basic/selinux-util.c

@@ -10,6 +10,7 @@

 #include <syslog.h>

 #if HAVE_SELINUX

+#include <selinux/avc.h>

 #include <selinux/context.h>

 #include <selinux/label.h>

 #include <selinux/selinux.h>

@@ -32,6 +33,8 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);

 #define _cleanup_freecon_ _cleanup_(freeconp)

 #define _cleanup_context_free_ _cleanup_(context_freep)

+static int mac_selinux_reload(int seqno);

+

 static int cached_use = -1;

 static struct selabel_handle *label_hnd = NULL;

@@ -63,6 +66,8 @@ int mac_selinux_init(void) {

         usec_t before_timestamp, after_timestamp;

         struct mallinfo before_mallinfo, after_mallinfo;

+        selinux_set_callback(SELINUX_CB_POLICYLOAD, (union selinux_callback) mac_selinux_reload);

+

         if (label_hnd)

                 return 0;

@@ -105,13 +110,12 @@ void mac_selinux_finish(void) {

 #endif

 }

-void mac_selinux_reload(void) {

-

 #if HAVE_SELINUX

+static int mac_selinux_reload(int seqno) {

         struct selabel_handle *backup_label_hnd;

         if (!label_hnd)

-                return;

+                return 0;

         backup_label_hnd = TAKE_PTR(label_hnd);

@@ -122,8 +126,10 @@ void mac_selinux_reload(void) {

                 selabel_close(backup_label_hnd);

         else

                 label_hnd = backup_label_hnd;

-#endif

+

+        return 0;

 }

+#endif

 int mac_selinux_fix(const char *path, LabelFixFlags flags) {

@@ -152,6 +158,9 @@ int mac_selinux_fix(const char *path, LabelFixFlags flags) {

         if (fstat(fd, &st) < 0)

                 return -errno;

+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */

+        (void) avc_netlink_check_nb();

+

         if (selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode) < 0) {

                 r = -errno;

@@ -345,6 +354,9 @@ static int selinux_create_file_prepare_abspath(const char *abspath, mode_t mode)

         assert(abspath);

         assert(path_is_absolute(abspath));

+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */

+        (void) avc_netlink_check_nb();

+

         r = selabel_lookup_raw(label_hnd, &filecon, abspath, mode);

         if (r < 0) {

                 /* No context specified by the policy? Proceed without setting it. */

@@ -496,6 +508,9 @@ int mac_selinux_bind(int fd, const struct sockaddr *addr, socklen_t addrlen) {

         path = strndupa(un->sun_path, addrlen - offsetof(struct sockaddr_un, sun_path));

+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */

+        (void) avc_netlink_check_nb();

+

         if (path_is_absolute(path))

                 r = selabel_lookup_raw(label_hnd, &fcon, path, S_IFSOCK);

         else {

diff --git a/src/basic/selinux-util.h b/src/basic/selinux-util.h

index 639c35b687..bd5207c318 100644

--- a/src/basic/selinux-util.h

+++ b/src/basic/selinux-util.h

@@ -13,7 +13,6 @@ void mac_selinux_retest(void);

 int mac_selinux_init(void);

 void mac_selinux_finish(void);

-void mac_selinux_reload(void);

 int mac_selinux_fix(const char *path, LabelFixFlags flags);

 int mac_selinux_apply(const char *path, const char *label);

diff --git a/src/core/main.c b/src/core/main.c

index d5c41da0c4..d897155644 100644

--- a/src/core/main.c

+++ b/src/core/main.c

@@ -1682,8 +1682,6 @@ static int invoke_main_loop(

                         saved_log_level = m->log_level_overridden ? log_get_max_level() : -1;

                         saved_log_target = m->log_target_overridden ? log_get_target() : _LOG_TARGET_INVALID;

-                        mac_selinux_reload();

-

                         (void) parse_configuration(saved_rlimit_nofile, saved_rlimit_memlock);

                         set_manager_defaults(m);