Fix boundary check problems in socket_host.cc.

content/browser/renderer_host/p2p/socket_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/p2p/socket_host.h"
 
 #include "base/sys_byteorder.h"
 #include "content/browser/renderer_host/p2p/socket_host_tcp.h"
 #include "content/browser/renderer_host/p2p/socket_host_tcp_server.h"
 #include "content/browser/renderer_host/p2p/socket_host_udp.h"
@@ skipping 15 matching lines @@
 const int kAbsSendTimeExtnLen = 3;
 const int kOneByteHdrLen = 1;
 
 // Fake auth tag written by the render process if external authentication is
 // enabled. HMAC in packet will be compared against this value before updating
 // packet with actual HMAC value.
 static const unsigned char kFakeAuthTag[10] = {
     0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd, 0xba, 0xdd
 };
 
-bool IsTurnChannelData(const char* data) {
-  return ((*data & 0xC0) == 0x40);
+bool IsTurnChannelData(const char* data, size_t len) {
+  return len >= kTurnChannelHdrLen && ((*data & 0xC0) == 0x40);
 }
 
-bool IsDtlsPacket(const char* data, int len) {
+bool IsDtlsPacket(const char* data, size_t len) {
   const uint8* u = reinterpret_cast<const uint8*>(data);
   return (len >= kDtlsRecordHeaderLen && (u[0] > 19 && u[0] < 64));
 }
 
 bool IsRtcpPacket(const char* data) {

[juberti2, 2014/09/22 22:43:57]

for completeness, perhaps check len against 2 here (or add a min RTCP packet len
== 8)

[jiayl, 2014/09/22 23:04:13]

Done.

   int type = (static_cast<uint8>(data[1]) & 0x7F);
   return (type >= 64 && type < 96);
 }
 
-bool IsTurnSendIndicationPacket(const char* data) {
+bool IsTurnSendIndicationPacket(const char* data, size_t len) {
+  if (len < content::P2PSocketHost::kStunHeaderSize)
+    return false;
+
   uint16 type = rtc::GetBE16(data);
   return (type == cricket::TURN_SEND_INDICATION);
 }
 
-bool IsRtpPacket(const char* data, int len) {
+bool IsRtpPacket(const char* data, size_t len) {
   return ((*data & 0xC0) == 0x80);
 }
 
 // Verifies rtp header and message length.
-bool ValidateRtpHeader(const char* rtp, int length, size_t* header_length) {
+bool ValidateRtpHeader(const char* rtp, size_t length, size_t* header_length) {
   if (header_length)
     *header_length = 0;
 
-  int cc_count = rtp[0] & 0x0F;
-  int rtp_hdr_len_without_extn = kMinRtpHdrLen + 4 * cc_count;
+  size_t cc_count = rtp[0] & 0x0F;
+  size_t rtp_hdr_len_without_extn = kMinRtpHdrLen + 4 * cc_count;
   if (rtp_hdr_len_without_extn > length) {
     return false;
   }
 
   // If extension bit is not set, we are done with header processing, as input
   // length is verified above.
   if (!(rtp[0] & 0x10)) {
     if (header_length)
       *header_length = rtp_hdr_len_without_extn;
 
     return true;
   }
 
   rtp += rtp_hdr_len_without_extn;
 
+  if (rtp_hdr_len_without_extn + kRtpExtnHdrLen > length) {
+    return false;
+  }
+
   // Getting extension profile length.
   // Length is in 32 bit words.
-  uint16 extn_length = rtc::GetBE16(rtp + 2) * 4;
+  uint16 extn_len_32bit_words = rtc::GetBE16(rtp + 2);
+  size_t extn_length = extn_len_32bit_words * 4;
+
+  size_t rtp_header_length =
+      extn_length + rtp_hdr_len_without_extn + kRtpExtnHdrLen;
 
   // Verify input length against total header size.
-  if (rtp_hdr_len_without_extn + kRtpExtnHdrLen + extn_length > length) {
+  if (rtp_header_length > length) {
     return false;
   }
 
   if (header_length)
-    *header_length = rtp_hdr_len_without_extn + kRtpExtnHdrLen + extn_length;
+    *header_length = rtp_header_length;
   return true;
 }
 
-void UpdateAbsSendTimeExtnValue(char* extn_data, int len,
+void UpdateAbsSendTimeExtnValue(char* extn_data, size_t len,
                                 uint32 abs_send_time) {
   // Absolute send time in RTP streams.
   //
   // The absolute send time is signaled to the receiver in-band using the
   // general mechanism for RTP header extensions [RFC5285]. The payload
   // of this extension (the transmitted value) is a 24-bit unsigned integer
   // containing the sender's current time in seconds as a fixed point number
   // with 18 bits fractional part.
   //
   // The form of the absolute send time extension block:
   //
   //    0                   1                   2                   3
   //    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   //   |  ID   | len=2 |              absolute send time               |
   //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-  DCHECK_EQ(len, kAbsSendTimeExtnLen);
+  if (len != kAbsSendTimeExtnLen) {
+    NOTREACHED();
+    return;
+  }
+
   // Now() has resolution ~1-15ms, using HighResNow(). But it is warned not to
   // use it unless necessary, as it is expensive than Now().
   uint32 now_second = abs_send_time;
   if (!now_second) {
     uint64 now_us =
         (base::TimeTicks::HighResNow() - base::TimeTicks()).InMicroseconds();
     // Convert second to 24-bit unsigned with 18 bit fractional part
     now_second =
         ((now_us << 18) / base::Time::kMicrosecondsPerSecond) & 0x00FFFFFF;
   }
   // TODO(mallinath) - Add SetBE24 to byteorder.h in libjingle.
   extn_data[0] = static_cast<uint8>(now_second >> 16);
   extn_data[1] = static_cast<uint8>(now_second >> 8);
   extn_data[2] = static_cast<uint8>(now_second);
 }
 
 // Assumes |len| is actual packet length + tag length. Updates HMAC at end of
 // the RTP packet.
-void UpdateRtpAuthTag(char* rtp, int len,
+void UpdateRtpAuthTag(char* rtp, size_t len,
                       const rtc::PacketOptions& options) {
   // If there is no key, return.
   if (options.packet_time_params.srtp_auth_key.empty())
     return;
 
   size_t tag_length = options.packet_time_params.srtp_auth_tag_len;
-  char* auth_tag = rtp + (len - tag_length);
 
-  // We should have a fake HMAC value @ auth_tag.
-  DCHECK_EQ(0, memcmp(auth_tag, kFakeAuthTag, tag_length));
+  const size_t kRocLength = 4;
+  if (tag_length < kRocLength || tag_length > len) {
+    NOTREACHED();
+    return;
+  }
 
   crypto::HMAC hmac(crypto::HMAC::SHA1);
   if (!hmac.Init(reinterpret_cast<const unsigned char*>(
         &options.packet_time_params.srtp_auth_key[0]),
         options.packet_time_params.srtp_auth_key.size())) {
     NOTREACHED();
     return;
   }
 
-  if (hmac.DigestLength() < tag_length) {
+  if (tag_length > hmac.DigestLength()) {
     NOTREACHED();
     return;
   }
 
+  char* auth_tag = rtp + (len - tag_length);
+
+  // We should have a fake HMAC value @ auth_tag.
+  DCHECK_EQ(0, memcmp(auth_tag, kFakeAuthTag, tag_length));
+
   // Copy ROC after end of rtp packet.
-  memcpy(auth_tag, &options.packet_time_params.srtp_packet_index, 4);
+  memcpy(auth_tag, &options.packet_time_params.srtp_packet_index, kRocLength);
   // Authentication of a RTP packet will have RTP packet + ROC size.
-  int auth_required_length = len - tag_length + 4;
+  int auth_required_length = len - tag_length + kRocLength;
 
   unsigned char output[64];
   if (!hmac.Sign(base::StringPiece(rtp, auth_required_length),
                  output, sizeof(output))) {
     NOTREACHED();
     return;
   }
   // Copy HMAC from output to packet. This is required as auth tag length
   // may not be equal to the actual HMAC length.
   memcpy(auth_tag, output, tag_length);
 }
 
 }  // namespace
 
 namespace content {
 
 namespace packet_processing_helpers {
 
-bool ApplyPacketOptions(char* data, int length,
+bool ApplyPacketOptions(char* data, size_t length,
                         const rtc::PacketOptions& options,
                         uint32 abs_send_time) {
   DCHECK(data != NULL);
   DCHECK(length > 0);
   // if there is no valid |rtp_sendtime_extension_id| and |srtp_auth_key| in
   // PacketOptions, nothing to be updated in this packet.
   if (options.packet_time_params.rtp_sendtime_extension_id == -1 &&
       options.packet_time_params.srtp_auth_key.empty()) {
     return true;
   }
 
   DCHECK(!IsDtlsPacket(data, length));
   DCHECK(!IsRtcpPacket(data));
 
   // If there is a srtp auth key present then packet must be a RTP packet.
   // RTP packet may have been wrapped in a TURN Channel Data or
   // TURN send indication.
-  int rtp_start_pos;
-  int rtp_length;
+  size_t rtp_start_pos;
+  size_t rtp_length;
   if (!GetRtpPacketStartPositionAndLength(
       data, length, &rtp_start_pos, &rtp_length)) {
     // This method should never return false.
     NOTREACHED();
     return false;
   }
 
   // Skip to rtp packet.
   char* start = data + rtp_start_pos;
   // If packet option has non default value (-1) for sendtime extension id,
   // then we should parse the rtp packet to update the timestamp. Otherwise
   // just calculate HMAC and update packet with it.
   if (options.packet_time_params.rtp_sendtime_extension_id != -1) {
     UpdateRtpAbsSendTimeExtn(
         start, rtp_length,
         options.packet_time_params.rtp_sendtime_extension_id, abs_send_time);
   }
 
   UpdateRtpAuthTag(start, rtp_length, options);
   return true;
 }
 
 bool GetRtpPacketStartPositionAndLength(const char* packet,
-                                        int length,
-                                        int* rtp_start_pos,
-                                        int* rtp_packet_length) {
-  int rtp_begin;
-  int rtp_length = 0;
-  if (IsTurnChannelData(packet)) {
+                                        size_t length,
+                                        size_t* rtp_start_pos,
+                                        size_t* rtp_packet_length) {
+  if (length < kMinRtpHdrLen)
+    return false;
+
+  size_t rtp_begin;
+  size_t rtp_length = 0;
+  if (IsTurnChannelData(packet, length)) {
     // Turn Channel Message header format.
     //   0                   1                   2                   3
     //  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     // |         Channel Number        |            Length             |
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     // |                                                               |
     // /                       Application Data                        /
     // /                                                               /
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    if (length < kTurnChannelHdrLen) {
-      return false;
-    }
-
     rtp_begin = kTurnChannelHdrLen;
     rtp_length = rtc::GetBE16(&packet[2]);
     if (length < rtp_length + kTurnChannelHdrLen) {
       return false;
     }
-  } else if (IsTurnSendIndicationPacket(packet)) {
-    if (length <= P2PSocketHost::kStunHeaderSize) {
-      // Message must be greater than 20 bytes, if it's carrying any payload.
-      return false;
-    }
+  } else if (IsTurnSendIndicationPacket(packet, length)) {
     // Validate STUN message length.
-    int stun_msg_len = rtc::GetBE16(&packet[2]);
+    size_t stun_msg_len = rtc::GetBE16(&packet[2]);
     if (stun_msg_len + P2PSocketHost::kStunHeaderSize != length) {
       return false;
     }
 
     // First skip mandatory stun header which is of 20 bytes.
     rtp_begin = P2PSocketHost::kStunHeaderSize;
     // Loop through STUN attributes until we find STUN DATA attribute.
     const char* start = packet + rtp_begin;
     bool data_attr_present = false;
-    while ((packet + rtp_begin) - start < stun_msg_len) {
+    while (packet + rtp_begin < start + stun_msg_len) {
       // Keep reading STUN attributes until we hit DATA attribute.
       // Attribute will be a TLV structure.
       // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       // |         Type                  |            Length             |
       // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       // |                         Value (variable)                ....
       // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       // The value in the length field MUST contain the length of the Value
       // part of the attribute, prior to padding, measured in bytes.  Since
       // STUN aligns attributes on 32-bit boundaries, attributes whose content
       // is not a multiple of 4 bytes are padded with 1, 2, or 3 bytes of
       // padding so that its value contains a multiple of 4 bytes.  The
       // padding bits are ignored, and may be any value.
       uint16 attr_type, attr_length;
+      const int kAttrHeaderLength = sizeof(attr_type) + sizeof(attr_length);
+
+      if (length < rtp_begin + kAttrHeaderLength) {
+        return false;
+      }
+
       // Getting attribute type and length.
       attr_type = rtc::GetBE16(&packet[rtp_begin]);
       attr_length = rtc::GetBE16(
           &packet[rtp_begin + sizeof(attr_type)]);
+
       // Checking for bogus attribute length.
-      if (length < attr_length + rtp_begin) {
+      if (length < rtp_begin + kAttrHeaderLength + attr_length) {
         return false;
       }
 
       if (attr_type != cricket::STUN_ATTR_DATA) {
-        rtp_begin += sizeof(attr_type) + sizeof(attr_length) + attr_length;
+        rtp_begin += kAttrHeaderLength + attr_length;
         if ((attr_length % 4) != 0) {
           rtp_begin += (4 - (attr_length % 4));
         }
         continue;
       }
 
       data_attr_present = true;
-      rtp_begin += 4;  // Skip STUN_DATA_ATTR header.
+      rtp_begin += kAttrHeaderLength;  // Skip STUN_DATA_ATTR header.
       rtp_length = attr_length;
-      // One final check of length before exiting.
-      if (length < rtp_length + rtp_begin) {
-        return false;
-      }
+
       // We found STUN_DATA_ATTR. We can skip parsing rest of the packet.
       break;
     }
 
     if (!data_attr_present) {
       // There is no data attribute present in the message. We can't do anything
       // with the message.
       return false;
     }
 
   } else {
     // This is a raw RTP packet.
     rtp_begin = 0;
     rtp_length = length;
   }
 
   // Making sure we have a valid RTP packet at the end.
   if ((rtp_length >= kMinRtpHdrLen) &&
       IsRtpPacket(packet + rtp_begin, rtp_length) &&
       ValidateRtpHeader(packet + rtp_begin, rtp_length, NULL)) {
     *rtp_start_pos = rtp_begin;
     *rtp_packet_length = rtp_length;
     return true;
   }
   return false;
 }
 
 // ValidateRtpHeader must be called before this method to make sure, we have
 // a sane rtp packet.
-bool UpdateRtpAbsSendTimeExtn(char* rtp, int length,
+bool UpdateRtpAbsSendTimeExtn(char* rtp, size_t length,
                               int extension_id, uint32 abs_send_time) {
   //  0                   1                   2                   3
   //  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   // |V=2|P|X|  CC   |M|     PT      |       sequence number         |
   // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   // |                           timestamp                           |
   // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   // |           synchronization source (SSRC) identifier            |
   // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
   // |            contributing source (CSRC) identifiers             |
   // |                             ....                              |
   // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
   // Return if extension bit is not set.
   if (!(rtp[0] & 0x10)) {
     return true;
   }
 
-  int cc_count = rtp[0] & 0x0F;
-  int rtp_hdr_len_without_extn = kMinRtpHdrLen + 4 * cc_count;
+  size_t cc_count = rtp[0] & 0x0F;
+  size_t rtp_hdr_len_without_extn = kMinRtpHdrLen + 4 * cc_count;
 
   rtp += rtp_hdr_len_without_extn;
 
   // Getting extension profile ID and length.
   uint16 profile_id = rtc::GetBE16(rtp);
   // Length is in 32 bit words.
-  uint16 extn_length = rtc::GetBE16(rtp + 2) * 4;
+  uint16 extn_len_32bit_words = rtc::GetBE16(rtp + 2);
+  size_t extn_length = extn_len_32bit_words * 4;
 
   rtp += kRtpExtnHdrLen;  // Moving past extn header.
 
   bool found = false;
   // WebRTC is using one byte header extension.
   // TODO(mallinath) - Handle two byte header extension.
   if (profile_id == 0xBEDE) {  // OneByte extension header
     //  0
     //  0 1 2 3 4 5 6 7
     // +-+-+-+-+-+-+-+-+
     // |  ID   |  len  |
     // +-+-+-+-+-+-+-+-+
 
     //  0                   1                   2                   3
     //  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     // |       0xBE    |    0xDE       |           length=3            |
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     // |  ID   | L=0   |     data      |  ID   |  L=1  |   data...
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //       ...data   |    0 (pad)    |    0 (pad)    |  ID   | L=3   |
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     // |                          data                                 |
     // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    char* extn_start = rtp;
-    while (rtp - extn_start < extn_length) {
+    const char* extn_start = rtp;
+    const char* extn_end = extn_start + extn_length;
+
+    while (rtp < extn_end) {
       const int id = (*rtp & 0xF0) >> 4;
-      const int len = (*rtp & 0x0F) + 1;
+      const size_t len = (*rtp & 0x0F) + 1;
+      if (rtp + kOneByteHdrLen + len > extn_end) {
+        return false;
+      }
       // The 4-bit length is the number minus one of data bytes of this header
       // extension element following the one-byte header.
       if (id == extension_id) {
         UpdateAbsSendTimeExtnValue(rtp + kOneByteHdrLen, len, abs_send_time);
         found = true;
         break;
       }
       rtp += kOneByteHdrLen + len;
       // Counting padding bytes.
-      while ((*rtp == 0) && (rtp - extn_start < extn_length)) {
+      while ((rtp < extn_end) && (*rtp == 0)) {
         ++rtp;
       }
     }
   }
   return found;
 }
 
 }  // packet_processing_helpers
 
 P2PSocketHost::P2PSocketHost(IPC::Sender* message_sender, int socket_id)
@@ skipping 117 matching lines @@
   if (!dump_incoming_rtp_packet_ && !dump_outgoing_rtp_packet_)
     packet_dump_callback_.Reset();
 }
 
 void P2PSocketHost::DumpRtpPacket(const char* packet,
                                   size_t length,
                                   bool incoming) {
   if (IsDtlsPacket(packet, length) || IsRtcpPacket(packet))
     return;
 
-  int rtp_packet_pos = 0;
-  int rtp_packet_length = length;
+  size_t rtp_packet_pos = 0;
+  size_t rtp_packet_length = length;
   if (!packet_processing_helpers::GetRtpPacketStartPositionAndLength(
           packet, length, &rtp_packet_pos, &rtp_packet_length))
     return;
 
   packet += rtp_packet_pos;
 
   size_t header_length = 0;
   bool valid = ValidateRtpHeader(packet, rtp_packet_length, &header_length);
   if (!valid) {
     DCHECK(false);
@@ skipping 31 matching lines @@
   BrowserThread::PostTask(BrowserThread::UI,
                           FROM_HERE,
                           base::Bind(packet_dump_callback_,
                                      Passed(&packet_header),
                                      header_length,
                                      packet_length,
                                      incoming));
 }
 
 }  // namespace content