daandemeyer / rpms / systemd

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From 4e48673172b012a06575e4f5b681d3554eded2e2 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com>
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Date: Mon, 6 Jan 2020 15:27:23 +0100
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Subject: [PATCH] selinux: add trigger for policy reload to refresh internal
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 selabel cache
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Reload the internal selabel cache automatically on SELinux policy reloads so non pid-1 daemons are participating.
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Run the reload function `mac_selinux_reload()` not manually on daemon-reload, but rather pass it as callback to libselinux.
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Trigger the callback prior usage of the systemd internal selabel cache by depleting the selinux netlink socket via `avc_netlink_check_nb()`.
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Improves: a9dfac21ec85 ("core: reload SELinux label cache on daemon-reload")
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Improves: #13363
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(cherry picked from commit 61f3e897f13101f29fb8027e8839498a469ad58e)
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Related: #1888912
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---
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 src/basic/selinux-util.c | 23 +++++++++++++++++++----
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 src/basic/selinux-util.h |  1 -
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 src/core/main.c          |  2 --
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 3 files changed, 19 insertions(+), 7 deletions(-)
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diff --git a/src/basic/selinux-util.c b/src/basic/selinux-util.c
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index a078ce23ef..bfe3d015aa 100644
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--- a/src/basic/selinux-util.c
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+++ b/src/basic/selinux-util.c
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@@ -10,6 +10,7 @@
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 #include <syslog.h>
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 #if HAVE_SELINUX
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+#include <selinux/avc.h>
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 #include <selinux/context.h>
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 #include <selinux/label.h>
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 #include <selinux/selinux.h>
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@@ -32,6 +33,8 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
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 #define _cleanup_freecon_ _cleanup_(freeconp)
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 #define _cleanup_context_free_ _cleanup_(context_freep)
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+static int mac_selinux_reload(int seqno);
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+
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 static int cached_use = -1;
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 static struct selabel_handle *label_hnd = NULL;
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@@ -63,6 +66,8 @@ int mac_selinux_init(void) {
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         usec_t before_timestamp, after_timestamp;
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         struct mallinfo before_mallinfo, after_mallinfo;
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+        selinux_set_callback(SELINUX_CB_POLICYLOAD, (union selinux_callback) mac_selinux_reload);
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+
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         if (label_hnd)
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                 return 0;
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@@ -105,13 +110,12 @@ void mac_selinux_finish(void) {
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 #endif
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 }
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-void mac_selinux_reload(void) {
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-
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 #if HAVE_SELINUX
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+static int mac_selinux_reload(int seqno) {
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         struct selabel_handle *backup_label_hnd;
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         if (!label_hnd)
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-                return;
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+                return 0;
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         backup_label_hnd = TAKE_PTR(label_hnd);
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@@ -122,8 +126,10 @@ void mac_selinux_reload(void) {
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                 selabel_close(backup_label_hnd);
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         else
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                 label_hnd = backup_label_hnd;
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-#endif
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+
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+        return 0;
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 }
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+#endif
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 int mac_selinux_fix(const char *path, LabelFixFlags flags) {
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@@ -152,6 +158,9 @@ int mac_selinux_fix(const char *path, LabelFixFlags flags) {
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         if (fstat(fd, &st) < 0)
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                 return -errno;
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+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
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+        (void) avc_netlink_check_nb();
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+
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         if (selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode) < 0) {
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                 r = -errno;
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@@ -345,6 +354,9 @@ static int selinux_create_file_prepare_abspath(const char *abspath, mode_t mode)
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         assert(abspath);
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         assert(path_is_absolute(abspath));
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+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
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+        (void) avc_netlink_check_nb();
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+
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         r = selabel_lookup_raw(label_hnd, &filecon, abspath, mode);
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         if (r < 0) {
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                 /* No context specified by the policy? Proceed without setting it. */
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@@ -496,6 +508,9 @@ int mac_selinux_bind(int fd, const struct sockaddr *addr, socklen_t addrlen) {
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         path = strndupa(un->sun_path, addrlen - offsetof(struct sockaddr_un, sun_path));
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+        /* Check for policy reload so 'label_hnd' is kept up-to-date by callbacks */
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+        (void) avc_netlink_check_nb();
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+
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         if (path_is_absolute(path))
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                 r = selabel_lookup_raw(label_hnd, &fcon, path, S_IFSOCK);
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         else {
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diff --git a/src/basic/selinux-util.h b/src/basic/selinux-util.h
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index 639c35b687..bd5207c318 100644
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--- a/src/basic/selinux-util.h
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+++ b/src/basic/selinux-util.h
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@@ -13,7 +13,6 @@ void mac_selinux_retest(void);
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 int mac_selinux_init(void);
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 void mac_selinux_finish(void);
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-void mac_selinux_reload(void);
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 int mac_selinux_fix(const char *path, LabelFixFlags flags);
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 int mac_selinux_apply(const char *path, const char *label);
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diff --git a/src/core/main.c b/src/core/main.c
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index d5c41da0c4..d897155644 100644
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--- a/src/core/main.c
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+++ b/src/core/main.c
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@@ -1682,8 +1682,6 @@ static int invoke_main_loop(
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                         saved_log_level = m->log_level_overridden ? log_get_max_level() : -1;
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                         saved_log_target = m->log_target_overridden ? log_get_target() : _LOG_TARGET_INVALID;
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-                        mac_selinux_reload();
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-
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                         (void) parse_configuration(saved_rlimit_nofile, saved_rlimit_memlock);
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                         set_manager_defaults(m);