Match app directories on expanded storage.

Expanded storage behaves mostly like the internal data storage,
including holding private app data.  To correctly apply SELinux
labels, this change defines a pattern for matching these new paths
which follow the format:

/mnt/expand/<UUID>/user/<N>

The owner user (0) is not special cased like internal storage, and
lives under the /user/0 directory.

Bug: 19993667
Change-Id: Ia3eb28440ff3a119f0a3892e636640cf59c01244

1 files changed, 18 insertions, 4 deletions

diff --git a/src/android.c b/src/android.c
index 440b54d..c4f8512 100644
--- a/src/android.c
+++ b/src/android.c
@@ -27,6 +27,7 @@
 #include "callbacks.h"
 #include "selinux_internal.h"
 #include "label_internal.h"
+#include <fnmatch.h>
 
 /*
  * XXX Where should this configuration file be located?
@@ -1055,6 +1056,7 @@ struct pkgInfo *package_info_lookup(const char *name)
 /* The path prefixes of package data directories. */
 #define DATA_DATA_PATH "/data/data"
 #define DATA_USER_PATH "/data/user"
+#define EXPAND_USER_PATH "/mnt/expand/????????-????-????-????-????????????/user"
 #define DATA_DATA_PREFIX DATA_DATA_PATH "/"
 #define DATA_USER_PREFIX DATA_USER_PATH "/"
 
@@ -1080,6 +1082,14 @@ static int pkgdir_selabel_lookup(const char *pathname,
             pathname++;
         else
             return 0;
+    } else if (!fnmatch(EXPAND_USER_PATH, pathname, FNM_LEADING_DIR|FNM_PATHNAME)) {
+        pathname += sizeof(EXPAND_USER_PATH);
+        while (isdigit(*pathname))
+            pathname++;
+        if (*pathname == '/')
+            pathname++;
+        else
+            return 0;
     } else
         return 0;
 
@@ -1168,7 +1178,8 @@ static int restorecon_sb(const char *pathname, const struct stat *sb,
      * installd is responsible for managing these labels instead of init.
      */
     if (!strncmp(pathname, DATA_DATA_PREFIX, sizeof(DATA_DATA_PREFIX)-1) ||
-        !strncmp(pathname, DATA_USER_PREFIX, sizeof(DATA_USER_PREFIX)-1)) {
+        !strncmp(pathname, DATA_USER_PREFIX, sizeof(DATA_USER_PREFIX)-1) ||
+        !fnmatch(EXPAND_USER_PATH, pathname, FNM_LEADING_DIR|FNM_PATHNAME)) {
         if (pkgdir_selabel_lookup(pathname, seinfo, uid, &secontext) < 0)
             goto err;
     }
@@ -1244,7 +1255,8 @@ static int selinux_android_restorecon_common(const char* pathname,
      * installd rather than init.
      */
     if (!strncmp(pathname, DATA_DATA_PREFIX, sizeof(DATA_DATA_PREFIX)-1) ||
-        !strncmp(pathname, DATA_USER_PREFIX, sizeof(DATA_USER_PREFIX)-1))
+        !strncmp(pathname, DATA_USER_PREFIX, sizeof(DATA_USER_PREFIX)-1) ||
+        !fnmatch(EXPAND_USER_PATH, pathname, FNM_LEADING_DIR|FNM_PATHNAME))
         setrestoreconlast = false;
 
     /* Also ignore on /sys since it is regenerated on each boot regardless. */
@@ -1296,9 +1308,11 @@ static int selinux_android_restorecon_common(const char* pathname,
                 fts_set(fts, ftsent, FTS_SKIP);
                 continue;
             }
+
             if (!datadata &&
-                (!strcmp(ftsent->fts_path, DATA_DATA_PATH) ||
-                 !strncmp(ftsent->fts_path, DATA_USER_PREFIX, sizeof(DATA_USER_PREFIX)-1))) {
+                (!strncmp(ftsent->fts_path, DATA_DATA_PREFIX, sizeof(DATA_DATA_PREFIX)-1) ||
+                 !strncmp(ftsent->fts_path, DATA_USER_PREFIX, sizeof(DATA_USER_PREFIX)-1) ||
+                 !fnmatch(EXPAND_USER_PATH, ftsent->fts_path, FNM_LEADING_DIR|FNM_PATHNAME))) {
                 // Don't label anything below this directory.
                 fts_set(fts, ftsent, FTS_SKIP);
                 // but fall through and make sure we label the directory itself