Revert "selinux: split up mac_selinux_have() from mac_selinux_use()"

This reverts commit 6355e75610a8d47fc3ba5ab8bd442172a2cfe574.

The previously mentioned commit inadvertently broke a lot of SELinux related
functionality for both unprivileged users and elogind instances running as
MANAGER_USER.  In particular, setting the correct SELinux context after a User=
directive is used would fail to work since we attempt to set the security
context after changing UID.  Additionally, it causes activated socket units to
be mislabeled for elogind --user processes since setsockcreatecon() would never
be called.

Reverting this fixes the issues with labeling outlined above, and reinstates
SELinux access checks on unprivileged user services.

4 files changed, 10 insertions, 21 deletions

diff --git a/src/basic/selinux-util.c b/src/basic/selinux-util.c
index 2a9dd7c8c..79ce6a856 100644
--- a/src/basic/selinux-util.c
+++ b/src/basic/selinux-util.c
@@ -53,7 +53,7 @@ static struct selabel_handle *label_hnd = NULL;
 #define log_enforcing(...) log_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG, __VA_ARGS__)
 #endif
 
-bool mac_selinux_have(void) {
+bool mac_selinux_use(void) {
 #ifdef HAVE_SELINUX
         if (cached_use < 0)
                 cached_use = is_selinux_enabled() > 0;
@@ -64,16 +64,6 @@ bool mac_selinux_have(void) {
 #endif
 }
 
-bool mac_selinux_use(void) {
-        if (!mac_selinux_have())
-                return false;
-
-        /* Never try to configure SELinux features if we aren't
-         * root */
-
-        return getuid() == 0;
-}
-
 void mac_selinux_retest(void) {
 #ifdef HAVE_SELINUX
         cached_use = -1;
@@ -206,7 +196,7 @@ int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
         assert(exe);
         assert(label);
 
-        if (!mac_selinux_have())
+        if (!mac_selinux_use())
                 return -EOPNOTSUPP;
 
         r = getcon_raw(&mycon);
@@ -232,7 +222,7 @@ int mac_selinux_get_our_label(char **label) {
         assert(label);
 
 #ifdef HAVE_SELINUX
-        if (!mac_selinux_have())
+        if (!mac_selinux_use())
                 return -EOPNOTSUPP;
 
         r = getcon_raw(label);
@@ -256,7 +246,7 @@ int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *
         assert(exe);
         assert(label);
 
-        if (!mac_selinux_have())
+        if (!mac_selinux_use())
                 return -EOPNOTSUPP;
 
         r = getcon_raw(&mycon);
@@ -311,7 +301,7 @@ char* mac_selinux_free(char *label) {
         if (!label)
                 return NULL;
 
-        if (!mac_selinux_have())
+        if (!mac_selinux_use())
                 return NULL;
 
 
diff --git a/src/basic/selinux-util.h b/src/basic/selinux-util.h
index fa41a65f8..2a71afefa 100644
--- a/src/basic/selinux-util.h
+++ b/src/basic/selinux-util.h
@@ -26,7 +26,6 @@
 #include "macro.h"
 
 bool mac_selinux_use(void);
-bool mac_selinux_have(void);
 void mac_selinux_retest(void);
 
 int mac_selinux_init(void);
diff --git a/src/libelogind/sd-bus/bus-socket.c b/src/libelogind/sd-bus/bus-socket.c
index e6ed15eb7..8b25002f0 100644
--- a/src/libelogind/sd-bus/bus-socket.c
+++ b/src/libelogind/sd-bus/bus-socket.c
@@ -607,7 +607,7 @@ static void bus_get_peercred(sd_bus *b) {
         b->ucred_valid = getpeercred(b->input_fd, &b->ucred) >= 0;
 
         /* Get the SELinux context of the peer */
-        if (mac_selinux_have()) {
+        if (mac_selinux_use()) {
                 r = getpeersec(b->input_fd, &b->label);
                 if (r < 0 && r != -EOPNOTSUPP)
                         log_debug_errno(r, "Failed to determine peer security context: %m");
diff --git a/src/test/test-selinux.c b/src/test/test-selinux.c
index 5687e1e2f..964a228a5 100644
--- a/src/test/test-selinux.c
+++ b/src/test/test-selinux.c
@@ -35,16 +35,16 @@ static void test_testing(void) {
         b = mac_selinux_use();
         log_info("mac_selinux_use → %s", yes_no(b));
 
-        b = mac_selinux_have();
-        log_info("mac_selinux_have → %s", yes_no(b));
+        b = mac_selinux_use();
+        log_info("mac_selinux_use → %s", yes_no(b));
 
         mac_selinux_retest();
 
         b = mac_selinux_use();
         log_info("mac_selinux_use → %s", yes_no(b));
 
-        b = mac_selinux_have();
-        log_info("mac_selinux_have → %s", yes_no(b));
+        b = mac_selinux_use();
+        log_info("mac_selinux_use → %s", yes_no(b));
 }
 
 static void test_loading(void) {