Listen for mDns traffic in setuid sandboxed Utility process.

Local discovery listens for mDns traffic inside Utility process with enabled setuid sandbox (seccomp-BPF is not enabled). Setuid sandbox fails ::socket calls. To overcome this we use LocalDiscoveryMsg_SetSockets IPC message to pass two new UDP sockets created in browser process. These sockets will be provided for net::MDnsClient using net::PlatformSocketFactory.

Added check to make sure that only Local Discovery Utility process handles LocalDiscovery* IPC messages.

This code, as well as Windows version, is not executed without --enable-device-discovery switch.

BUG=277654

Review URL: https://chromiumcodereview.appspot.com/23482003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220760 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 10 insertions, 10 deletions

diff --git a/net/dns/mdns_client_impl.cc b/net/dns/mdns_client_impl.cc
index a90ac64..d8e5e9b 100644
--- a/net/dns/mdns_client_impl.cc
+++ b/net/dns/mdns_client_impl.cc
@@ -41,11 +41,6 @@ MDnsConnection::SocketHandler::~SocketHandler() {
 }
 
 int MDnsConnection::SocketHandler::Start() {
-  int rv = BindSocket();
-  if (rv != OK) {
-    return rv;
-  }
-
   return DoLoop(0);
 }
 
@@ -87,7 +82,7 @@ void MDnsConnection::SocketHandler::SendDone(int rv) {
   // TODO(noamsml): Retry logic.
 }
 
-int MDnsConnection::SocketHandler::BindSocket() {
+int MDnsConnection::SocketHandler::Bind() {
   IPAddressNumber address_any(multicast_addr_.address().size());
 
   IPEndPoint bind_endpoint(address_any, multicast_addr_.port());
@@ -117,8 +112,13 @@ MDnsConnection::~MDnsConnection() {
 }
 
 int MDnsConnection::Init() {
-  int rv;
-
+  int rv = socket_handler_ipv4_.Bind();
+  if (rv != OK) return rv;
+  rv = socket_handler_ipv6_.Bind();
+  if (rv != OK) return rv;
+  // All unbound sockets need to be bound before processing untrusted input.
+  // This is done for security reasons, so that an attacker can't get an unbound
+  // socket.
   rv = socket_handler_ipv4_.Start();
   if (rv != OK) return rv;
   rv = socket_handler_ipv6_.Start();
diff --git a/net/dns/mdns_client_impl.h b/net/dns/mdns_client_impl.h
index 9fe3f99..86a7ba9 100644
--- a/net/dns/mdns_client_impl.h
+++ b/net/dns/mdns_client_impl.h
@@ -58,13 +58,13 @@ class NET_EXPORT_PRIVATE MDnsConnection {
                   const IPEndPoint& multicast_addr,
                   SocketFactory* socket_factory);
     ~SocketHandler();
-    int DoLoop(int rv);
+    int Bind();
     int Start();
 
     int Send(IOBuffer* buffer, unsigned size);
 
    private:
-    int BindSocket();
+    int DoLoop(int rv);
     void OnDatagramReceived(int rv);
 
     // Callback for when sending a query has finished.