smack: never follow symlinks when relabelling

[elogind.git] / src / shared / smack-util.c

diff --git a/src/shared/smack-util.c b/src/shared/smack-util.c
index df194e0844b8204289ec1d94f56769e7c5586bd2..c345488d2ed99f89afa6b5f01207514e76c59ca2 100644 (file)
--- a/src/shared/smack-util.c
+++ b/src/shared/smack-util.c
@@ -21,71 +21,149 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include <unistd.h>
-#include <string.h>
-#ifdef HAVE_XATTR
-#include <attr/xattr.h>
-#endif
+#include <sys/xattr.h>
 
+#include "util.h"
+#include "path-util.h"
 #include "smack-util.h"
 
-bool use_smack(void) {
+bool mac_smack_use(void) {
 #ifdef HAVE_SMACK
-        static int use_smack_cached = -1;
+        static int cached_use = -1;
 
-        if (use_smack_cached < 0)
-                use_smack_cached = access("/sys/fs/smackfs/", F_OK) >= 0;
+        if (cached_use < 0)
+                cached_use = access("/sys/fs/smackfs/", F_OK) >= 0;
 
-        return use_smack_cached;
+        return cached_use;
 #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)
+                r = lsetxattr(path, "security.SMACK64", label, strlen(label), 0);
+        else
+                r = lremovexattr(path, "security.SMACK64");
+        if (r < 0)
+                return -errno;
+#endif
 
+        return r;
 }
 
-int smack_label_path(const char *path, const char *label) {
+int mac_smack_apply_fd(int fd, const char *label) {
+        int r = 0;
+
+        assert(fd >= 0);
+
 #ifdef HAVE_SMACK
-        if (!use_smack())
+        if (!mac_smack_use())
                 return 0;
 
         if (label)
-                return setxattr(path, "security.SMACK64", label, strlen(label), 0);
+                r = fsetxattr(fd, "security.SMACK64", label, strlen(label), 0);
         else
-                return lremovexattr(path, "security.SMACK64");
-#else
-        return 0;
+                r = fremovexattr(fd, "security.SMACK64");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
-int smack_label_fd(int fd, const char *label) {
+int mac_smack_apply_ip_out_fd(int fd, const char *label) {
+        int r = 0;
+
+        assert(fd >= 0);
+
 #ifdef HAVE_SMACK
-        if (!use_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.SMACK64IPOUT", label, strlen(label), 0);
+        else
+                r = fremovexattr(fd, "security.SMACK64IPOUT");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
-int smack_label_ip_out_fd(int fd, const char *label) {
+int mac_smack_apply_ip_in_fd(int fd, const char *label) {
+        int r = 0;
+
+        assert(fd >= 0);
+
 #ifdef HAVE_SMACK
-        if (!use_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.SMACK64IPIN", label, strlen(label), 0);
+        else
+                r = fremovexattr(fd, "security.SMACK64IPIN");
+        if (r < 0)
+                return -errno;
 #endif
+
+        return r;
 }
 
-int smack_label_ip_in_fd(int fd, const char *label) {
+int mac_smack_fix(const char *path) {
+        int r = 0;
+
 #ifdef HAVE_SMACK
-        if (!use_smack())
+        struct stat sb;
+        const char *label;
+#endif
+
+        assert(path);
+
+#ifdef HAVE_SMACK
+        if (!mac_smack_use())
                 return 0;
 
-        return fsetxattr(fd, "security.SMACK64IPIN", label, strlen(label), 0);
-#else
-        return 0;
+        /*
+         * Path must be in /dev and must exist
+         */
+        if (!path_startswith(path, "/dev"))
+                return 0;
+
+        r = lstat(path, &sb);
+        if (r < 0)
+                return -errno;
+
+        /*
+         * Label directories and character devices "*".
+         * Label symlinks "_".
+         * Don't change anything else.
+         */
+        if (S_ISDIR(sb.st_mode))
+                label = SMACK_STAR_LABEL;
+        else if (S_ISLNK(sb.st_mode))
+                label = SMACK_FLOOR_LABEL;
+        else if (S_ISCHR(sb.st_mode))
+                label = SMACK_STAR_LABEL;
+        else
+                return 0;
+
+        r = setxattr(path, "security.SMACK64", label, strlen(label), 0);
+        if (r < 0) {
+                log_error("Smack relabeling \"%s\" %m", path);
+                return -errno;
+        }
 #endif
+
+        return r;
 }