Add support for reloading policy from /data/system.

To support runtime policy management, add support for reloading
policy from /data/system.  This can be triggered by setting the
selinux.loadpolicy property to 1, whether from init.rc after
mounting /data or from the system_server (e.g. upon invocation of
a new device admin API for provisioning policy). ueventd and
installd are restarted upon policy reloads to pick up the new
policy configurations relevant to their operation.

Change-Id: I97479aecef8cec23b32f60e09cc778cc5520b691
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

init/devices.c

@@ -33,6 +33,7 @@
 #ifdef HAVE_SELINUX
 #include <selinux/selinux.h>
 #include <selinux/label.h>
+#include <selinux/android.h>
 #endif
 
 #include <private/android_filesystem_config.h>
@@ -871,12 +872,10 @@ void device_init(void)
     struct stat info;
     int fd;
 #ifdef HAVE_SELINUX
-    struct selinux_opt seopts[] = {
-        { SELABEL_OPT_PATH, "/file_contexts" }
-    };
-
-    if (is_selinux_enabled() > 0)
-        sehandle = selabel_open(SELABEL_CTX_FILE, seopts, 1);
+    sehandle = NULL;
+    if (is_selinux_enabled() > 0) {
+        sehandle = selinux_android_file_context_handle();
+    }
 #endif
     /* is 64K enough? udev uses 16MB! */
     device_fd = uevent_open_socket(64*1024, true);

init/init.c

@@ -33,9 +33,9 @@
 #include <sys/un.h>
 
 #ifdef HAVE_SELINUX
-#include <sys/mman.h>
 #include <selinux/selinux.h>
 #include <selinux/label.h>
+#include <selinux/android.h>
 #endif
 
 #include <libgen.h>
@@ -77,7 +77,6 @@ static char qemu[32];
 
 #ifdef HAVE_SELINUX
 static int selinux_enabled = 1;
-static int selinux_enforcing = 0;
 #endif
 
 static struct action *cur_action = NULL;
@@ -604,9 +603,7 @@ static void import_kernel_nv(char *name, int for_emulator)
     if (name_len == 0) return;
 
 #ifdef HAVE_SELINUX
-    if (!strcmp(name,"enforcing")) {
-        selinux_enforcing = atoi(value);
-    } else if (!strcmp(name,"selinux")) {
+    if (!strcmp(name,"selinux")) {
         selinux_enabled = atoi(value);
     }
 #endif
@@ -758,93 +755,28 @@ static int bootchart_init_action(int nargs, char **args)
 #endif
 
 #ifdef HAVE_SELINUX
-void selinux_load_policy(void)
+void selinux_init_all_handles(void)
 {
-    const char path_prefix[] = "/sepolicy";
-    struct selinux_opt seopts[] = {
-        { SELABEL_OPT_PATH, "/file_contexts" }
-    };
-    char path[PATH_MAX];
-    int fd, rc, vers;
-    struct stat sb;
-    void *map;
+    sehandle = selinux_android_file_context_handle();
+}
 
-    sehandle = NULL;
+int selinux_reload_policy(void)
+{
     if (!selinux_enabled) {
-        INFO("SELinux:  Disabled by command line option\n");
-        return;
+        return -1;
     }
 
-    mkdir(SELINUXMNT, 0755);
-    if (mount("selinuxfs", SELINUXMNT, "selinuxfs", 0, NULL)) {
-        if (errno == ENODEV) {
-            /* SELinux not enabled in kernel */
-            return;
-        }
-        ERROR("SELinux:  Could not mount selinuxfs:  %s\n",
-              strerror(errno));
-        return;
-    }
-    set_selinuxmnt(SELINUXMNT);
+    INFO("SELinux: Attempting to reload policy files\n");
 
-    vers = security_policyvers();
-    if (vers <= 0) {
-        ERROR("SELinux:  Unable to read policy version\n");
-        return;
+    if (selinux_android_reload_policy() == -1) {
+        return -1;
     }
-    INFO("SELinux:  Maximum supported policy version:  %d\n", vers);
 
-    snprintf(path, sizeof(path), "%s.%d",
-             path_prefix, vers);
-    fd = open(path, O_RDONLY);
-    while (fd < 0 && errno == ENOENT && --vers) {
-        snprintf(path, sizeof(path), "%s.%d",
-                 path_prefix, vers);
-        fd = open(path, O_RDONLY);
-    }
-    if (fd < 0) {
-        ERROR("SELinux:  Could not open %s:  %s\n",
-              path, strerror(errno));
-        return;
-    }
-    if (fstat(fd, &sb) < 0) {
-        ERROR("SELinux:  Could not stat %s:  %s\n",
-              path, strerror(errno));
-        return;
-    }
-    map = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-    if (map == MAP_FAILED) {
-        ERROR("SELinux:  Could not map %s:  %s\n",
-              path, strerror(errno));
-        return;
-    }
+    if (sehandle)
+        selabel_close(sehandle);
 
-    rc = security_load_policy(map, sb.st_size);
-    if (rc < 0) {
-        ERROR("SELinux:  Could not load policy:  %s\n",
-              strerror(errno));
-        return;
-    }
-
-    rc = security_setenforce(selinux_enforcing);
-    if (rc < 0) {
-        ERROR("SELinux:  Could not set enforcing mode to %s:  %s\n",
-              selinux_enforcing ? "enforcing" : "permissive", strerror(errno));
-        return;
-    }
-
-    munmap(map, sb.st_size);
-    close(fd);
-    INFO("SELinux: Loaded policy from %s\n", path);
-
-    sehandle = selabel_open(SELABEL_CTX_FILE, seopts, 1);
-    if (!sehandle) {
-        ERROR("SELinux:  Could not load file_contexts:  %s\n",
-              strerror(errno));
-        return;
-    }
-    INFO("SELinux: Loaded file contexts from %s\n", seopts[0].value);
-    return;
+    selinux_init_all_handles();
+    return 0;
 }
 #endif
 
@@ -900,8 +832,17 @@ int main(int argc, char **argv)
 
 #ifdef HAVE_SELINUX
     INFO("loading selinux policy\n");
-    selinux_load_policy();
-    /* These directories were necessarily created before policy load
+    if (selinux_enabled) {
+        if (selinux_android_load_policy() < 0) {
+            selinux_enabled = 0;
+            INFO("SELinux: Disabled due to failed policy load\n");
+        } else {
+            selinux_init_all_handles();
+        }
+    } else {
+        INFO("SELinux:  Disabled by command line option\n");
+    }
+    /* These directories were necessarily created before initial policy load
      * and therefore need their security context restored to the proper value.
      * This must happen before /dev is populated by ueventd.
      */

init/init.h

@@ -138,6 +138,7 @@ int load_565rle_image( char *file_name );
 
 #ifdef HAVE_SELINUX
 extern struct selabel_handle *sehandle;
+extern int selinux_reload_policy(void);
 #endif
 
 #endif	/* _INIT_INIT_H */

init/property_service.c

@@ -86,6 +86,7 @@ struct {
     { "persist.sys.",     AID_SYSTEM,   0 },
     { "persist.service.", AID_SYSTEM,   0 },
     { "persist.security.", AID_SYSTEM,   0 },
+    { "selinux."         , AID_SYSTEM,   0 },
     { NULL, 0, 0 }
 };
 
@@ -334,6 +335,11 @@ int property_set(const char *name, const char *value)
          * to prevent them from being overwritten by default values.
          */
         write_persistent_property(name, value);
+#ifdef HAVE_SELINUX
+    } else if (strcmp("selinux.reload_policy", name) == 0 &&
+               strcmp("1", value) == 0) {
+        selinux_reload_policy();
+#endif
     }
     property_changed(name, value);
     return 0;

rootdir/init.rc

@@ -355,6 +355,10 @@ service ueventd /sbin/ueventd
     critical
     seclabel u:r:ueventd:s0
 
+on property:selinux.reload_policy=1
+    restart ueventd
+    restart installd
+
 service console /system/bin/sh
     class core
     console

toolbox/restorecon.c

@@ -7,8 +7,7 @@
 #include <fts.h>
 #include <selinux/selinux.h>
 #include <selinux/label.h>
-
-#define FCPATH "/file_contexts"
+#include <selinux/android.h>
 
 static struct selabel_handle *sehandle;
 static const char *progname;
@@ -17,7 +16,7 @@ static int verbose;
 
 static void usage(void)
 {
-    fprintf(stderr, "usage:  %s [-f file_contexts] [-nrRv] pathname...\n", progname);
+    fprintf(stderr, "usage:  %s [-nrRv] pathname...\n", progname);
     exit(1);
 }
 
@@ -54,21 +53,16 @@ static int restore(const char *pathname, const struct stat *sb)
 
 int restorecon_main(int argc, char **argv)
 {
-    struct selinux_opt seopts[] = {
-        { SELABEL_OPT_PATH, FCPATH }
-    };
     int ch, recurse = 0, ftsflags = FTS_PHYSICAL;
+    int i = 0;
 
     progname = argv[0];
 
     do {
-        ch = getopt(argc, argv, "f:nrRv");
+        ch = getopt(argc, argv, "nrRv");
         if (ch == EOF)
             break;
         switch (ch) {
-        case 'f':
-            seopts[0].value = optarg;
-            break;
         case 'n':
             nochange = 1;
             break;
@@ -89,9 +83,10 @@ int restorecon_main(int argc, char **argv)
     if (!argc)
         usage();
 
-    sehandle = selabel_open(SELABEL_CTX_FILE, seopts, 1);
+    sehandle = selinux_android_file_context_handle();
+
     if (!sehandle) {
-        fprintf(stderr, "Could not load file contexts from %s:  %s\n", seopts[0].value,
+        fprintf(stderr, "Could not load file_contexts:  %s\n",
                 strerror(errno));
         return -1;
     }