Update OTA to understand SELinux labels and capabilities

Update the OTA generation script to understand SELinux file
labels and file capabilities.

Make fs_config aware of SELinux labels and file capabilities, and
optionally output those elements whenever we output the
UID / GID / file perms. The information is emitted as a key=value pair
to allow for future extensibility.

Pass the SELinux file label and capabilities to the newly created
set_metadata() and set_metadata_recursive() calls. When the OTA
script fixes up filesystem permissions, it will also fix up the SELinux
labels and file capabilities.

If no SELinux label and capabilities are available for the file, use
the old set_perm and set_perm_recursive calls.

Bug: 8985290
Bug: 10183961
Bug: 10186213
Change-Id: I4fcfb2c234dbfb965cee9e62f060092a4274d22d

core/Makefile

@@ -1173,6 +1173,7 @@ $(BUILT_TARGET_FILES_PACKAGE): \
 		$(INSTALLED_CACHEIMAGE_TARGET) \
 		$(INSTALLED_VENDORIMAGE_TARGET) \
 		$(INSTALLED_ANDROID_INFO_TXT_TARGET) \
+		$(SELINUX_FC) \
 		$(built_ota_tools) \
 		$(APKCERTS_FILE) \
 		$(HOST_OUT_EXECUTABLES)/fs_config \
@@ -1260,13 +1261,14 @@ ifdef PRODUCT_EXTRA_RECOVERY_KEYS
 	$(hide) echo "extra_recovery_keys=$(PRODUCT_EXTRA_RECOVERY_KEYS)" >> $(zip_root)/META/misc_info.txt
 endif
 	$(hide) echo "mkbootimg_args=$(BOARD_MKBOOTIMG_ARGS)" >> $(zip_root)/META/misc_info.txt
+	$(hide) echo "use_set_metadata=1" >> $(zip_root)/META/misc_info.txt
 	$(call generate-userimage-prop-dictionary, $(zip_root)/META/misc_info.txt)
 	@# Zip everything up, preserving symlinks
 	$(hide) (cd $(zip_root) && zip -qry ../$(notdir $@) .)
 	@# Run fs_config on all the system, boot ramdisk, and recovery ramdisk files in the zip, and save the output
-	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="SYSTEM/" } /^SYSTEM\// {print "system/" $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config > $(zip_root)/META/filesystem_config.txt
+	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="SYSTEM/" } /^SYSTEM\// {print "system/" $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config -C -S $(SELINUX_FC) > $(zip_root)/META/filesystem_config.txt
-	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="BOOT/RAMDISK/" } /^BOOT\/RAMDISK\// {print $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config > $(zip_root)/META/boot_filesystem_config.txt
+	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="BOOT/RAMDISK/" } /^BOOT\/RAMDISK\// {print $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config -C -S $(SELINUX_FC) > $(zip_root)/META/boot_filesystem_config.txt
-	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="RECOVERY/RAMDISK/" } /^RECOVERY\/RAMDISK\// {print $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config > $(zip_root)/META/recovery_filesystem_config.txt
+	$(hide) zipinfo -1 $@ | awk 'BEGIN { FS="RECOVERY/RAMDISK/" } /^RECOVERY\/RAMDISK\// {print $$2}' | $(HOST_OUT_EXECUTABLES)/fs_config -C -S $(SELINUX_FC) > $(zip_root)/META/recovery_filesystem_config.txt
 	$(hide) (cd $(zip_root) && zip -q ../$(notdir $@) META/*filesystem_config.txt)
 
 .PHONY: target-files-package

tools/fs_config/Android.mk

@@ -17,6 +17,7 @@ include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES := fs_config.c
 LOCAL_MODULE := fs_config
+LOCAL_STATIC_LIBRARIES := libselinux
 LOCAL_FORCE_STATIC_EXECUTABLE := true
 
 include $(BUILD_HOST_EXECUTABLE)

tools/fs_config/fs_config.c

@@ -15,10 +15,16 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/stat.h>
 #include <errno.h>
 #include <unistd.h>
 #include <string.h>
+#include <inttypes.h>
+
+#include <selinux/selinux.h>
+#include <selinux/label.h>
+#include <selinux/android.h>
 
 #include "private/android_filesystem_config.h"
 
@@ -27,21 +33,67 @@
 // filename along with its desired uid, gid, and mode (in octal).
 // The leading slash should be stripped from the input.
 //
+// After the first 4 columns, optional key=value pairs are emitted
+// for each file.  Currently, the following keys are supported:
+// * -S: selabel=[selinux_label]
+// * -C: capabilities=[hex capabilities value]
+//
 // Example input:
 //
-//    system/etc/dbus.conf
+//      system/etc/dbus.conf
-//    data/app/
+//      data/app/
 //
 // Output:
 //
-//    system/etc/dbus.conf 1002 1002 440
+//      system/etc/dbus.conf 1002 1002 440
-//    data/app 1000 1000 771
+//      data/app 1000 1000 771
+//
+//   or if, for example, -S is used:
+//
+//      system/etc/dbus.conf 1002 1002 440 selabel=u:object_r:system_file:s0
+//      data/app 1000 1000 771 selabel=u:object_r:apk_data_file:s0
 //
 // Note that the output will omit the trailing slash from
 // directories.
 
+static struct selabel_handle* get_sehnd(const char* context_file) {
+  struct selinux_opt seopts[] = { { SELABEL_OPT_PATH, context_file } };
+  struct selabel_handle* sehnd = selabel_open(SELABEL_CTX_FILE, seopts, 1);
+
+  if (!sehnd) {
+    perror("error running selabel_open");
+    exit(EXIT_FAILURE);
+  }
+  return sehnd;
+}
+
+static void usage() {
+  fprintf(stderr, "Usage: fs_config [-S context_file] [-C]\n");
+}
+
 int main(int argc, char** argv) {
   char buffer[1024];
+  const char* context_file = NULL;
+  struct selabel_handle* sehnd = NULL;
+  int print_capabilities = 0;
+  int opt;
+  while((opt = getopt(argc, argv, "CS:")) != -1) {
+    switch(opt) {
+    case 'C':
+      print_capabilities = 1;
+      break;
+    case 'S':
+      context_file = optarg;
+      break;
+    default:
+      usage();
+      exit(EXIT_FAILURE);
+    }
+  }
+
+  if (context_file != NULL) {
+    sehnd = get_sehnd(context_file);
+  }
 
   while (fgets(buffer, 1023, stdin) != NULL) {
     int is_dir = 0;
@@ -64,7 +116,40 @@ int main(int argc, char** argv) {
     unsigned uid = 0, gid = 0, mode = 0;
     uint64_t capabilities;
     fs_config(buffer, is_dir, &uid, &gid, &mode, &capabilities);
-    printf("%s %d %d %o\n", buffer, uid, gid, mode);
+    printf("%s %d %d %o", buffer, uid, gid, mode);
+
+    if (sehnd != NULL) {
+      size_t buffer_strlen = strnlen(buffer, sizeof(buffer));
+      if (buffer_strlen >= sizeof(buffer)) {
+        fprintf(stderr, "non null terminated buffer, aborting\n");
+        exit(EXIT_FAILURE);
+      }
+      size_t full_name_size = buffer_strlen + 2;
+      char* full_name = (char*) malloc(full_name_size);
+      if (full_name == NULL) {
+        perror("malloc");
+        exit(EXIT_FAILURE);
+      }
+
+      full_name[0] = '/';
+      strncpy(full_name + 1, buffer, full_name_size - 1);
+      full_name[full_name_size - 1] = '\0';
+
+      char* secontext;
+      if (selabel_lookup(sehnd, &secontext, full_name, ( mode | (is_dir ? S_IFDIR : S_IFREG)))) {
+        secontext = strdup("u:object_r:unlabeled:s0");
+      }
+
+      printf(" selabel=%s", secontext);
+      free(full_name);
+      freecon(secontext);
+    }
+
+    if (print_capabilities) {
+      printf(" capabilities=0x%" PRIx64, capabilities);
+    }
+
+    printf("\n");
   }
   return 0;
 }

tools/releasetools/edify_generator.py

@@ -217,14 +217,33 @@ class EdifyGenerator(object):
       else:
         raise ValueError("don't know how to write \"%s\" partitions" % (p.fs_type,))
 
-  def SetPermissions(self, fn, uid, gid, mode):
+  def SetPermissions(self, fn, uid, gid, mode, selabel, capabilities):
     """Set file ownership and permissions."""
-    self.script.append('set_perm(%d, %d, 0%o, "%s");' % (uid, gid, mode, fn))
+    if not self.info.get("use_set_metadata", False):
+      self.script.append('set_perm(%d, %d, 0%o, "%s");' % (uid, gid, mode, fn))
+    else:
+      if capabilities is None: capabilities = "0x0"
+      cmd = 'set_metadata("%s", "uid", %d, "gid", %d, "mode", 0%o, ' \
+          '"capabilities", %s' % (fn, uid, gid, mode, capabilities)
+      if selabel is not None:
+        cmd += ', "selabel", "%s"' % ( selabel )
+      cmd += ');'
+      self.script.append(cmd)
 
-  def SetPermissionsRecursive(self, fn, uid, gid, dmode, fmode):
+  def SetPermissionsRecursive(self, fn, uid, gid, dmode, fmode, selabel, capabilities):
     """Recursively set path ownership and permissions."""
-    self.script.append('set_perm_recursive(%d, %d, 0%o, 0%o, "%s");'
+    if not self.info.get("use_set_metadata", False):
-                       % (uid, gid, dmode, fmode, fn))
+      self.script.append('set_perm_recursive(%d, %d, 0%o, 0%o, "%s");'
+                         % (uid, gid, dmode, fmode, fn))
+    else:
+      if capabilities is None: capabilities = "0x0"
+      cmd = 'set_metadata_recursive("%s", "uid", %d, "gid", %d, ' \
+          '"dmode", 0%o, "fmode", 0%o, "capabilities", %s' \
+          % (fn, uid, gid, dmode, fmode, capabilities)
+      if selabel is not None:
+        cmd += ', "selabel", "%s"' % ( selabel )
+      cmd += ');'
+      self.script.append(cmd)
 
   def MakeSymlinks(self, symlink_list):
     """Create symlinks, given a list of (dest, link) pairs."""

tools/releasetools/ota_from_target_files

@@ -117,6 +117,8 @@ class Item:
     self.uid = None
     self.gid = None
     self.mode = None
+    self.selabel = None
+    self.capabilities = None
     self.dir = dir
 
     if name:
@@ -147,82 +149,88 @@ class Item:
   @classmethod
   def GetMetadata(cls, input_zip):
 
-    try:
+    # The target_files contains a record of what the uid,
-      # See if the target_files contains a record of what the uid,
+    # gid, and mode are supposed to be.
-      # gid, and mode is supposed to be.
+    output = input_zip.read("META/filesystem_config.txt")
-      output = input_zip.read("META/filesystem_config.txt")
-    except KeyError:
-      # Run the external 'fs_config' program to determine the desired
-      # uid, gid, and mode for every Item object.  Note this uses the
-      # one in the client now, which might not be the same as the one
-      # used when this target_files was built.
-      p = common.Run(["fs_config"], stdin=subprocess.PIPE,
-                     stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-      suffix = { False: "", True: "/" }
-      input = "".join(["%s%s\n" % (i.name, suffix[i.dir])
-                       for i in cls.ITEMS.itervalues() if i.name])
-      output, error = p.communicate(input)
-      assert not error
 
     for line in output.split("\n"):
       if not line: continue
-      name, uid, gid, mode = line.split()
+      columns = line.split()
+      name, uid, gid, mode = columns[:4]
+      selabel = None
+      capabilities = None
+
+      # After the first 4 columns, there are a series of key=value
+      # pairs. Extract out the fields we care about.
+      for element in columns[4:]:
+        key, value = element.split("=")
+        if key == "selabel":
+          selabel = value
+        if key == "capabilities":
+          capabilities = value
+
       i = cls.ITEMS.get(name, None)
       if i is not None:
         i.uid = int(uid)
         i.gid = int(gid)
         i.mode = int(mode, 8)
+        i.selabel = selabel
+        i.capabilities = capabilities
         if i.dir:
           i.children.sort(key=lambda i: i.name)
 
     # set metadata for the files generated by this script.
     i = cls.ITEMS.get("system/recovery-from-boot.p", None)
-    if i: i.uid, i.gid, i.mode = 0, 0, 0644
+    if i: i.uid, i.gid, i.mode, i.selabel, i.capabilities = 0, 0, 0644, None, None
     i = cls.ITEMS.get("system/etc/install-recovery.sh", None)
-    if i: i.uid, i.gid, i.mode = 0, 0, 0544
+    if i: i.uid, i.gid, i.mode, i.selabel, i.capabilities = 0, 0, 0544, None, None
 
   def CountChildMetadata(self):
-    """Count up the (uid, gid, mode) tuples for all children and
+    """Count up the (uid, gid, mode, selabel, capabilities) tuples for
-    determine the best strategy for using set_perm_recursive and
+    all children and determine the best strategy for using set_perm_recursive and
     set_perm to correctly chown/chmod all the files to their desired
     values.  Recursively calls itself for all descendants.
 
-    Returns a dict of {(uid, gid, dmode, fmode): count} counting up
+    Returns a dict of {(uid, gid, dmode, fmode, selabel, capabilities): count} counting up
     all descendants of this node.  (dmode or fmode may be None.)  Also
     sets the best_subtree of each directory Item to the (uid, gid,
-    dmode, fmode) tuple that will match the most descendants of that
+    dmode, fmode, selabel, capabilities) tuple that will match the most
-    Item.
+    descendants of that Item.
     """
 
     assert self.dir
-    d = self.descendants = {(self.uid, self.gid, self.mode, None): 1}
+    d = self.descendants = {(self.uid, self.gid, self.mode, None, self.selabel, self.capabilities): 1}
     for i in self.children:
       if i.dir:
         for k, v in i.CountChildMetadata().iteritems():
           d[k] = d.get(k, 0) + v
       else:
-        k = (i.uid, i.gid, None, i.mode)
+        k = (i.uid, i.gid, None, i.mode, i.selabel, i.capabilities)
         d[k] = d.get(k, 0) + 1
 
-    # Find the (uid, gid, dmode, fmode) tuple that matches the most
+    # Find the (uid, gid, dmode, fmode, selabel, capabilities)
-    # descendants.
+    # tuple that matches the most descendants.
 
     # First, find the (uid, gid) pair that matches the most
     # descendants.
     ug = {}
-    for (uid, gid, _, _), count in d.iteritems():
+    for (uid, gid, _, _, _, _), count in d.iteritems():
       ug[(uid, gid)] = ug.get((uid, gid), 0) + count
     ug = MostPopularKey(ug, (0, 0))
 
-    # Now find the dmode and fmode that match the most descendants
+    # Now find the dmode, fmode, selabel, and capabilities that match
-    # with that (uid, gid), and choose those.
+    # the most descendants with that (uid, gid), and choose those.
     best_dmode = (0, 0755)
     best_fmode = (0, 0644)
+    best_selabel = (0, None)
+    best_capabilities = (0, None)
     for k, count in d.iteritems():
       if k[:2] != ug: continue
       if k[2] is not None and count >= best_dmode[0]: best_dmode = (count, k[2])
       if k[3] is not None and count >= best_fmode[0]: best_fmode = (count, k[3])
-    self.best_subtree = ug + (best_dmode[1], best_fmode[1])
+      if k[4] is not None and count >= best_selabel[0]: best_selabel = (count, k[4])
+      if k[5] is not None and count >= best_capabilities[0]: best_capabilities = (count, k[5])
+    self.best_subtree = ug + (best_dmode[1], best_fmode[1], best_selabel[1], best_capabilities[1])
 
     return d
 
@@ -234,7 +242,7 @@ class Item:
     self.CountChildMetadata()
 
     def recurse(item, current):
-      # current is the (uid, gid, dmode, fmode) tuple that the current
+      # current is the (uid, gid, dmode, fmode, selabel, capabilities) tuple that the current
       # item (and all its children) have already been set to.  We only
       # need to issue set_perm/set_perm_recursive commands if we're
       # supposed to be something different.
@@ -244,17 +252,21 @@ class Item:
           current = item.best_subtree
 
         if item.uid != current[0] or item.gid != current[1] or \
-           item.mode != current[2]:
+           item.mode != current[2] or item.selabel != current[4] or \
-          script.SetPermissions("/"+item.name, item.uid, item.gid, item.mode)
+           item.capabilities != current[5]:
+          script.SetPermissions("/"+item.name, item.uid, item.gid,
+                                item.mode, item.selabel, item.capabilities)
 
         for i in item.children:
           recurse(i, current)
       else:
         if item.uid != current[0] or item.gid != current[1] or \
-               item.mode != current[3]:
+               item.mode != current[3] or item.selabel != current[4] or \
-          script.SetPermissions("/"+item.name, item.uid, item.gid, item.mode)
+               item.capabilities != current[5]:
+          script.SetPermissions("/"+item.name, item.uid, item.gid,
+                                item.mode, item.selabel, item.capabilities)
 
-    recurse(self, (-1, -1, -1, -1))
+    recurse(self, (-1, -1, -1, -1, None, None))
 
 
 def CopySystemFiles(input_zip, output_zip=None,
@@ -733,7 +745,7 @@ def WriteIncrementalOTAPackage(target_zip, source_zip, output_zip):
   for item in deferred_patch_list:
     fn, tf, sf, size, _ = item
     script.ApplyPatch("/"+fn, "-", tf.size, tf.sha1, sf.sha1, "patch/"+fn+".p")
-  script.SetPermissions("/system/build.prop", 0, 0, 0644)
+  script.SetPermissions("/system/build.prop", 0, 0, 0644, None, None)
 
   script.AddToZip(target_zip, output_zip)
   WriteMetadata(metadata, output_zip)