smack: rework smack APIs a bit

a) always return negative errno error codes
b) always become a noop if smack is off
c) always take a NULL label as a request to remove it

3 files changed, 81 insertions, 29 deletions

diff --git a/src/core/socket.c b/src/core/socket.c
index abe829ade1..780015012f 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -807,6 +807,8 @@ static void socket_close_fds(Socket *s) {
 }
 
 static void socket_apply_socket_options(Socket *s, int fd) {
+        int r;
+
         assert(s);
         assert(fd >= 0);
 
@@ -894,7 +896,7 @@ static void socket_apply_socket_options(Socket *s, int fd) {
                         log_warning_unit(UNIT(s)->id, "IP_TOS failed: %m");
 
         if (s->ip_ttl >= 0) {
-                int r, x;
+                int x;
 
                 r = setsockopt(fd, IPPROTO_IP, IP_TTL, &s->ip_ttl, sizeof(s->ip_ttl));
 
@@ -920,27 +922,34 @@ static void socket_apply_socket_options(Socket *s, int fd) {
                         log_warning_unit(UNIT(s)->id, "SO_REUSEPORT failed: %m");
         }
 
-        if (s->smack_ip_in)
-                if (mac_smack_apply_ip_in_fd(fd, s->smack_ip_in) < 0)
-                        log_error_unit(UNIT(s)->id, "mac_smack_apply_ip_in_fd: %m");
+        if (s->smack_ip_in) {
+                r = mac_smack_apply_ip_in_fd(fd, s->smack_ip_in);
+                if (r < 0)
+                        log_error_unit(UNIT(s)->id, "mac_smack_apply_ip_in_fd: %s", strerror(-r));
+        }
 
-        if (s->smack_ip_out)
-                if (mac_smack_apply_ip_out_fd(fd, s->smack_ip_out) < 0)
-                        log_error_unit(UNIT(s)->id, "mac_smack_apply_ip_out_fd: %m");
+        if (s->smack_ip_out) {
+                r = mac_smack_apply_ip_out_fd(fd, s->smack_ip_out);
+                if (r < 0)
+                        log_error_unit(UNIT(s)->id, "mac_smack_apply_ip_out_fd: %s", strerror(-r));
+        }
 }
 
 static void socket_apply_fifo_options(Socket *s, int fd) {
+        int r;
+
         assert(s);
         assert(fd >= 0);
 
         if (s->pipe_size > 0)
                 if (fcntl(fd, F_SETPIPE_SZ, s->pipe_size) < 0)
-                        log_warning_unit(UNIT(s)->id,
-                                         "F_SETPIPE_SZ: %m");
+                        log_warning_unit(UNIT(s)->id, "F_SETPIPE_SZ: %m");
 
-        if (s->smack)
-                if (mac_smack_apply_fd(fd, s->smack) < 0)
-                        log_error_unit(UNIT(s)->id, "mac_smack_apply_fd: %m");
+        if (s->smack) {
+                r = mac_smack_apply_fd(fd, s->smack);
+                if (r < 0)
+                        log_error_unit(UNIT(s)->id, "mac_smack_apply_fd: %s", strerror(-r));
+        }
 }
 
 static int fifo_address_create(
diff --git a/src/shared/smack-util.c b/src/shared/smack-util.c
index 7726d69b0f..4a94922a43 100644
--- a/src/shared/smack-util.c
+++ b/src/shared/smack-util.c
@@ -38,54 +38,86 @@ bool mac_smack_use(void) {
 #else
         return false;
 #endif
-
 }
 
 int mac_smack_apply(const char *path, const char *label) {
+        int r = 0;
+
+        assert(path);
+
 #ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
         if (label)
-                return setxattr(path, "security.SMACK64", label, strlen(label), 0);
+                r = setxattr(path, "security.SMACK64", label, strlen(label), 0);
         else
-                return lremovexattr(path, "security.SMACK64");
-#else
-        return 0;
+                r = lremovexattr(path, "security.SMACK64");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
 int mac_smack_apply_fd(int fd, const char *label) {
+        int r = 0;
+
+        assert(fd >= 0);
+
 #ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
-        return fsetxattr(fd, "security.SMACK64", label, strlen(label), 0);
-#else
-        return 0;
+        if (label)
+                r = fsetxattr(fd, "security.SMACK64", label, strlen(label), 0);
+        else
+                r = fremovexattr(fd, "security.SMACK64");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
 int mac_smack_apply_ip_out_fd(int fd, const char *label) {
+        int r = 0;
+
+        assert(fd >= 0);
+
 #ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
-        return fsetxattr(fd, "security.SMACK64IPOUT", label, strlen(label), 0);
-#else
-        return 0;
+        if (label)
+                r = fsetxattr(fd, "security.SMACK64IPOUT", label, strlen(label), 0);
+        else
+                r = fremovexattr(fd, "security.SMACK64IPOUT");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
 int mac_smack_apply_ip_in_fd(int fd, const char *label) {
+        int r = 0;
+
+        assert(fd >= 0);
+
 #ifdef HAVE_SMACK
         if (!mac_smack_use())
                 return 0;
 
-        return fsetxattr(fd, "security.SMACK64IPIN", label, strlen(label), 0);
-#else
-        return 0;
+        if (label)
+                r = fsetxattr(fd, "security.SMACK64IPIN", label, strlen(label), 0);
+        else
+                r = fremovexattr(fd, "security.SMACK64IPIN");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
 int mac_smack_fix(const char *path) {
@@ -94,6 +126,13 @@ int mac_smack_fix(const char *path) {
 #ifdef HAVE_SMACK
         struct stat sb;
         const char *label;
+#endif
+
+        assert(path);
+
+#ifdef HAVE_SMACK
+        if (!mac_smack_use())
+                return 0;
 
         /*
          * Path must be in /dev and must exist
diff --git a/src/udev/udev-node.c b/src/udev/udev-node.c
index 803d803279..8d5bada5a4 100644
--- a/src/udev/udev-node.c
+++ b/src/udev/udev-node.c
@@ -294,21 +294,25 @@ static int node_permissions_apply(struct udev_device *dev, bool apply,
                 /* apply SECLABEL{$module}=$label */
                 udev_list_entry_foreach(entry, udev_list_get_entry(seclabel_list)) {
                         const char *name, *label;
+                        int r;
 
                         name = udev_list_entry_get_name(entry);
                         label = udev_list_entry_get_value(entry);
 
                         if (streq(name, "selinux")) {
                                 selinux = true;
+
                                 if (mac_selinux_apply(devnode, label) < 0)
-                                        log_error("SECLABEL: failed to set SELinux label '%s'", label);
+                                        log_error("SECLABEL: failed to set SELinux label '%s': %s", label, strerror(-r));
                                 else
                                         log_debug("SECLABEL: set SELinux label '%s'", label);
 
                         } else if (streq(name, "smack")) {
                                 smack = true;
-                                if (mac_smack_apply(devnode, label) < 0)
-                                        log_error("SECLABEL: failed to set SMACK label '%s'", label);
+
+                                r = mac_smack_apply(devnode, label);
+                                if (r < 0)
+                                        log_error("SECLABEL: failed to set SMACK label '%s': %s", label, strerror(-r));
                                 else
                                         log_debug("SECLABEL: set SMACK label '%s'", label);