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authorJeff Sharkey <jsharkey@android.com>2016-09-16 12:12:17 -0600
committerJeff Sharkey <jsharkey@android.com>2016-09-16 12:18:36 -0600
commit7c1af8c62c8bdf6e8de5a00c1927daf9fd9c03d1 (patch)
treed9f5d59b900e8bb7662d1ef7e36f394ac5fb8518 /src/com/android/providers/downloads
parentb440ceb00fd46c9233723066c680a538067fbf82 (diff)
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Enforce calling identity before clearing.
When opening a downloaded file, enforce that the caller can actually see the requested download before clearing their identity to read internal columns. However, this means that we can no longer return the "my_downloads" paths: if those Uris were shared beyond the app that requested the download, access would be denied. Instead, we need to switch to using "all_downloads" Uris so that permission grants can be issued to third-party viewer apps. Since an app requesting a download doesn't normally have permission to "all_downloads" paths, we issue narrow grants toward the owner of each download, both at device boot and when new downloads are started. Bug: 30537115, 30945409 Change-Id: If944aada020878a91c363963728d0da9f6fae3ea
Diffstat (limited to 'src/com/android/providers/downloads')
-rw-r--r--src/com/android/providers/downloads/DownloadProvider.java44
1 files changed, 44 insertions, 0 deletions
diff --git a/src/com/android/providers/downloads/DownloadProvider.java b/src/com/android/providers/downloads/DownloadProvider.java
index 2d914c41..87084130 100644
--- a/src/com/android/providers/downloads/DownloadProvider.java
+++ b/src/com/android/providers/downloads/DownloadProvider.java
@@ -458,6 +458,19 @@ public final class DownloadProvider extends ContentProvider {
if (appInfo != null) {
mDefContainerUid = appInfo.uid;
}
+
+ // Grant access permissions for all known downloads to the owning apps
+ final SQLiteDatabase db = mOpenHelper.getReadableDatabase();
+ final Cursor cursor = db.query(DB_TABLE, new String[] {
+ Downloads.Impl._ID, Constants.UID }, null, null, null, null, null);
+ try {
+ while (cursor.moveToNext()) {
+ grantAllDownloadsPermission(cursor.getLong(0), cursor.getInt(1));
+ }
+ } finally {
+ cursor.close();
+ }
+
// start the DownloadService class. don't wait for the 1st download to be issued.
// saves us by getting some initialization code in DownloadService out of the way.
Context context = getContext();
@@ -675,6 +688,7 @@ public final class DownloadProvider extends ContentProvider {
}
insertRequestHeaders(db, rowID, values);
+ grantAllDownloadsPermission(rowID, Binder.getCallingUid());
notifyContentChanged(uri, match);
// Always start service to handle notifications and/or scanning
@@ -1166,6 +1180,7 @@ public final class DownloadProvider extends ContentProvider {
try {
while (cursor.moveToNext()) {
final long id = cursor.getLong(0);
+ revokeAllDownloadsPermission(id);
DownloadStorageProvider.onDownloadProviderDelete(getContext(), id);
}
} finally {
@@ -1192,6 +1207,19 @@ public final class DownloadProvider extends ContentProvider {
logVerboseOpenFileInfo(uri, mode);
}
+ // Perform normal query to enforce caller identity access before
+ // clearing it to reach internal-only columns
+ final Cursor probeCursor = query(uri, new String[] {
+ Downloads.Impl._DATA }, null, null, null);
+ try {
+ if ((probeCursor == null) || (probeCursor.getCount() == 0)) {
+ throw new FileNotFoundException(
+ "No file found for " + uri + " as UID " + Binder.getCallingUid());
+ }
+ } finally {
+ IoUtils.closeQuietly(probeCursor);
+ }
+
final Cursor cursor = queryCleared(uri, new String[] {
Downloads.Impl._DATA, Downloads.Impl.COLUMN_STATUS,
Downloads.Impl.COLUMN_DESTINATION, Downloads.Impl.COLUMN_MEDIA_SCANNED }, null,
@@ -1373,4 +1401,20 @@ public final class DownloadProvider extends ContentProvider {
to.put(key, defaultValue);
}
}
+
+ private void grantAllDownloadsPermission(long id, int uid) {
+ final String[] packageNames = getContext().getPackageManager().getPackagesForUid(uid);
+ if (packageNames == null || packageNames.length == 0) return;
+
+ // We only need to grant to the first package, since the
+ // platform internally tracks based on UIDs
+ final Uri uri = ContentUris.withAppendedId(Downloads.Impl.ALL_DOWNLOADS_CONTENT_URI, id);
+ getContext().grantUriPermission(packageNames[0], uri,
+ Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
+ }
+
+ private void revokeAllDownloadsPermission(long id) {
+ final Uri uri = ContentUris.withAppendedId(Downloads.Impl.ALL_DOWNLOADS_CONTENT_URI, id);
+ getContext().revokeUriPermission(uri, ~0);
+ }
}