webrtc_m130/pc/srtp_session_unittest.cc
Philipp Hancke 9ff254eaf2 srtp: stop using private libsrtp function to determine packet index
instead use the standard API to get the rollover counter and
determine the extended sequence number which is the basis for the packet index.

See https://github.com/cisco/libsrtp/issues/738 and
https://github.com/cisco/libsrtp/issues/721

BUG=webrtc:357776213

Change-Id: I90c5a4a538f56132158aa48db8700187fcdb47d2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/371960
Commit-Queue: Philipp Hancke <phancke@meta.com>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43802}
2025-01-26 22:10:27 -08:00

394 lines
16 KiB
C++

/*
* Copyright 2004 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "pc/srtp_session.h"
#include <string.h>
#include <cstdint>
#include <cstring>
#include <limits>
#include <vector>
#include "media/base/fake_rtp.h"
#include "pc/test/srtp_test_util.h"
#include "rtc_base/buffer.h"
#include "rtc_base/byte_order.h"
#include "rtc_base/copy_on_write_buffer.h"
#include "rtc_base/ssl_stream_adapter.h" // For rtc::SRTP_*
#include "system_wrappers/include/metrics.h"
#include "test/gmock.h"
#include "test/gtest.h"
#include "test/scoped_key_value_config.h"
#include "third_party/libsrtp/include/srtp.h"
using ::testing::ElementsAre;
using ::testing::Pair;
namespace rtc {
std::vector<int> kEncryptedHeaderExtensionIds;
class SrtpSessionTest : public ::testing::Test {
public:
SrtpSessionTest() : s1_(field_trials_), s2_(field_trials_) {
webrtc::metrics::Reset();
}
protected:
virtual void SetUp() {
rtp_len_ = sizeof(kPcmuFrame);
rtcp_len_ = sizeof(kRtcpReport);
rtp_packet_.EnsureCapacity(rtp_len_ + 10);
rtp_packet_.SetData(kPcmuFrame, rtp_len_);
rtcp_packet_.EnsureCapacity(rtcp_len_ + 4 + 10);
rtcp_packet_.SetData(kRtcpReport, rtcp_len_);
}
void TestProtectRtp(int crypto_suite) {
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
EXPECT_EQ(rtp_packet_.size(), rtp_len_ + rtp_auth_tag_len(crypto_suite));
// Check that Protect changed the content (up to the original length).
EXPECT_NE(0, std::memcmp(kPcmuFrame, rtp_packet_.data(), rtp_len_));
rtp_len_ = rtp_packet_.size();
}
void TestProtectRtcp(int crypto_suite) {
EXPECT_TRUE(s1_.ProtectRtcp(rtcp_packet_));
EXPECT_EQ(rtcp_packet_.size(),
rtcp_len_ + 4 + rtcp_auth_tag_len(crypto_suite));
// Check that Protect changed the content (up to the original length).
EXPECT_NE(0, std::memcmp(kRtcpReport, rtcp_packet_.data(), rtcp_len_));
rtcp_len_ = rtcp_packet_.size();
}
void TestUnprotectRtp(int crypto_suite) {
EXPECT_TRUE(s2_.UnprotectRtp(rtp_packet_));
EXPECT_EQ(rtp_packet_.size(), sizeof(kPcmuFrame));
EXPECT_EQ(0,
std::memcmp(kPcmuFrame, rtp_packet_.data(), rtp_packet_.size()));
}
void TestUnprotectRtcp(int crypto_suite) {
EXPECT_TRUE(s2_.UnprotectRtcp(rtcp_packet_));
EXPECT_EQ(rtcp_packet_.size(), sizeof(kRtcpReport));
EXPECT_EQ(
0, std::memcmp(kRtcpReport, rtcp_packet_.data(), rtcp_packet_.size()));
}
webrtc::test::ScopedKeyValueConfig field_trials_;
cricket::SrtpSession s1_;
cricket::SrtpSession s2_;
rtc::CopyOnWriteBuffer rtp_packet_;
rtc::CopyOnWriteBuffer rtcp_packet_;
size_t rtp_len_;
size_t rtcp_len_;
};
// Test that we can set up the session and keys properly.
TEST_F(SrtpSessionTest, TestGoodSetup) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
}
// Test that we can't change the keys once set.
TEST_F(SrtpSessionTest, TestBadSetup) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_FALSE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey2,
kEncryptedHeaderExtensionIds));
EXPECT_FALSE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey2,
kEncryptedHeaderExtensionIds));
}
// Test that we fail keys of the wrong length.
TEST_F(SrtpSessionTest, TestKeysTooShort) {
EXPECT_FALSE(s1_.SetSend(kSrtpAes128CmSha1_80,
rtc::ZeroOnFreeBuffer<uint8_t>(kTestKey1.data(), 1),
kEncryptedHeaderExtensionIds));
EXPECT_FALSE(s2_.SetReceive(
kSrtpAes128CmSha1_80, rtc::ZeroOnFreeBuffer<uint8_t>(kTestKey1.data(), 1),
kEncryptedHeaderExtensionIds));
}
// Test that we can encrypt and decrypt RTP/RTCP using AES_CM_128_HMAC_SHA1_80.
TEST_F(SrtpSessionTest, TestProtect_AES_CM_128_HMAC_SHA1_80) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
TestProtectRtp(kSrtpAes128CmSha1_80);
TestProtectRtcp(kSrtpAes128CmSha1_80);
TestUnprotectRtp(kSrtpAes128CmSha1_80);
TestUnprotectRtcp(kSrtpAes128CmSha1_80);
}
// Test that we can encrypt and decrypt RTP/RTCP using AES_CM_128_HMAC_SHA1_32.
TEST_F(SrtpSessionTest, TestProtect_AES_CM_128_HMAC_SHA1_32) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_32, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_32, kTestKey1,
kEncryptedHeaderExtensionIds));
TestProtectRtp(kSrtpAes128CmSha1_32);
TestProtectRtcp(kSrtpAes128CmSha1_32);
TestUnprotectRtp(kSrtpAes128CmSha1_32);
TestUnprotectRtcp(kSrtpAes128CmSha1_32);
}
TEST_F(SrtpSessionTest, TestGetSendStreamPacketIndex) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_32, kTestKey1,
kEncryptedHeaderExtensionIds));
int64_t index;
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_, &index));
// `index` will be shifted by 16.
int64_t be64_index = static_cast<int64_t>(NetworkToHost64(1 << 16));
EXPECT_EQ(be64_index, index);
}
// Test that we fail to unprotect if someone tampers with the RTP/RTCP paylaods.
TEST_F(SrtpSessionTest, TestTamperReject) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
TestProtectRtp(kSrtpAes128CmSha1_80);
rtp_packet_.MutableData<uint8_t>()[0] = 0x12;
EXPECT_FALSE(s2_.UnprotectRtp(rtp_packet_));
EXPECT_METRIC_THAT(
webrtc::metrics::Samples("WebRTC.PeerConnection.SrtpUnprotectError"),
ElementsAre(Pair(srtp_err_status_bad_param, 1)));
TestProtectRtcp(kSrtpAes128CmSha1_80);
rtcp_packet_.MutableData<uint8_t>()[1] = 0x34;
EXPECT_FALSE(s2_.UnprotectRtcp(rtcp_packet_));
EXPECT_METRIC_THAT(
webrtc::metrics::Samples("WebRTC.PeerConnection.SrtcpUnprotectError"),
ElementsAre(Pair(srtp_err_status_auth_fail, 1)));
}
// Test that we fail to unprotect if the payloads are not authenticated.
TEST_F(SrtpSessionTest, TestUnencryptReject) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_FALSE(s2_.UnprotectRtp(rtp_packet_));
EXPECT_METRIC_THAT(
webrtc::metrics::Samples("WebRTC.PeerConnection.SrtpUnprotectError"),
ElementsAre(Pair(srtp_err_status_auth_fail, 1)));
EXPECT_FALSE(s2_.UnprotectRtcp(rtcp_packet_));
EXPECT_METRIC_THAT(
webrtc::metrics::Samples("WebRTC.PeerConnection.SrtcpUnprotectError"),
ElementsAre(Pair(srtp_err_status_cant_check, 1)));
}
// Test that we fail when using buffers that are too small.
TEST_F(SrtpSessionTest, TestBuffersTooSmall) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
// This buffer does not have extra capacity which we treat as an error.
rtc::CopyOnWriteBuffer rtp_packet(rtp_packet_.data(), rtp_packet_.size(),
rtp_packet_.size());
EXPECT_FALSE(s1_.ProtectRtp(rtp_packet));
// This buffer does not have extra capacity which we treat as an error.
rtc::CopyOnWriteBuffer rtcp_packet(rtcp_packet_.data(), rtcp_packet_.size(),
rtcp_packet_.size());
EXPECT_FALSE(s1_.ProtectRtcp(rtcp_packet));
}
TEST_F(SrtpSessionTest, TestReplay) {
static const uint16_t kMaxSeqnum = std::numeric_limits<uint16_t>::max() - 1;
static const uint16_t seqnum_big = 62275;
static const uint16_t seqnum_small = 10;
static const uint16_t replay_window = 1024;
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
// Initial sequence number.
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2, seqnum_big);
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
rtp_packet_.SetData(kPcmuFrame, sizeof(kPcmuFrame));
// Replay within the 1024 window should succeed.
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2,
seqnum_big - replay_window + 1);
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
rtp_packet_.SetData(kPcmuFrame, sizeof(kPcmuFrame));
// Replay out side of the 1024 window should fail.
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2,
seqnum_big - replay_window - 1);
EXPECT_FALSE(s1_.ProtectRtp(rtp_packet_));
rtp_packet_.SetData(kPcmuFrame, sizeof(kPcmuFrame));
// Increment sequence number to a small number.
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2, seqnum_small);
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
// Replay around 0 but out side of the 1024 window should fail.
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2,
kMaxSeqnum + seqnum_small - replay_window - 1);
EXPECT_FALSE(s1_.ProtectRtp(rtp_packet_));
rtp_packet_.SetData(kPcmuFrame, sizeof(kPcmuFrame));
// Replay around 0 but within the 1024 window should succeed.
for (uint16_t seqnum = 65000; seqnum < 65003; ++seqnum) {
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2, seqnum);
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
rtp_packet_.SetData(kPcmuFrame, sizeof(kPcmuFrame));
}
// Go back to normal sequence nubmer.
// NOTE: without the fix in libsrtp, this would fail. This is because
// without the fix, the loop above would keep incrementing local sequence
// number in libsrtp, eventually the new sequence number would go out side
// of the window.
SetBE16(rtp_packet_.MutableData<uint8_t>() + 2, seqnum_small + 1);
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
}
TEST_F(SrtpSessionTest, RemoveSsrc) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
// Encrypt and decrypt the packet once.
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
EXPECT_TRUE(s2_.UnprotectRtp(rtp_packet_));
EXPECT_EQ(sizeof(kPcmuFrame), rtp_packet_.size());
EXPECT_EQ(0, std::memcmp(kPcmuFrame, rtp_packet_.data(), rtp_packet_.size()));
// Recreate the original packet and encrypt again.
rtp_packet_.SetData(kPcmuFrame, sizeof(kPcmuFrame));
EXPECT_TRUE(s1_.ProtectRtp(rtp_packet_));
// Attempting to decrypt will fail as a replay attack.
// (srtp_err_status_replay_fail) since the sequence number was already seen.
EXPECT_FALSE(s2_.UnprotectRtp(rtp_packet_));
// Remove the fake packet SSRC 1 from the session.
EXPECT_TRUE(s2_.RemoveSsrcFromSession(1));
EXPECT_FALSE(s2_.RemoveSsrcFromSession(1));
// Since the SRTP state was discarded, this is no longer a replay attack.
EXPECT_TRUE(s2_.UnprotectRtp(rtp_packet_));
EXPECT_EQ(sizeof(kPcmuFrame), rtp_packet_.size());
EXPECT_EQ(0, std::memcmp(kPcmuFrame, rtp_packet_.data(), rtp_packet_.size()));
EXPECT_TRUE(s2_.RemoveSsrcFromSession(1));
}
TEST_F(SrtpSessionTest, ProtectUnprotectWrapAroundRocMismatch) {
// This unit tests demonstrates why you should be careful when
// choosing the initial RTP sequence number as there can be decryption
// failures when it wraps around with packet loss. Pick your starting
// sequence number in the lower half of the range for robustness reasons,
// see packet_sequencer.cc for the code doing so.
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
// Buffers include enough room for the 10 byte SRTP auth tag so we can
// encrypt in place.
unsigned char kFrame1[] = {
// clang-format off
// PT=0, SN=65535, TS=0, SSRC=1
0x80, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
0xBE, 0xEF, // data bytes
// Space for the SRTP auth tag
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
// clang-format on
};
rtc::CopyOnWriteBuffer packet1(kFrame1, sizeof(kFrame1) - 10,
sizeof(kFrame1));
unsigned char kFrame2[] = {
// clang-format off
// PT=0, SN=1, TS=0, SSRC=1
0x80, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
0xBE, 0xEF, // data bytes
// Space for the SRTP auth tag
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
// clang-format on
};
rtc::CopyOnWriteBuffer packet2(kFrame2, sizeof(kFrame2) - 10,
sizeof(kFrame1));
const unsigned char kPayload[] = {0xBE, 0xEF};
// Encrypt the frames in-order. There is a sequence number rollover from
// 65535 to 1 (skipping 0) and the second packet gets encrypted with a
// roll-over counter (ROC) of 1. See
// https://datatracker.ietf.org/doc/html/rfc3711#section-3.3.1
EXPECT_TRUE(s1_.ProtectRtp(packet1));
EXPECT_EQ(packet1.size(), 24u);
EXPECT_TRUE(s1_.ProtectRtp(packet2));
EXPECT_EQ(packet2.size(), 24u);
// If we decrypt frame 2 first it will have a ROC of 1 but the receiver
// does not know this is a rollover so will attempt with a ROC of 0.
// Note: If libsrtp is modified to attempt to decrypt with ROC=1 for this
// case, this test will fail and needs to be modified accordingly to unblock
// the roll. See https://issues.webrtc.org/353565743 for details.
EXPECT_FALSE(s2_.UnprotectRtp(packet2));
// Decrypt frame 1.
EXPECT_TRUE(s2_.UnprotectRtp(packet1));
ASSERT_EQ(packet1.size(), 14u);
EXPECT_EQ(0, std::memcmp(packet1.data() + 12, kPayload, sizeof(kPayload)));
// Now decrypt frame 2 again. A rollover is detected which increases
// the ROC to 1 so this succeeds.
EXPECT_TRUE(s2_.UnprotectRtp(packet2));
ASSERT_EQ(packet2.size(), 14u);
EXPECT_EQ(0, std::memcmp(packet2.data() + 12, kPayload, sizeof(kPayload)));
}
TEST_F(SrtpSessionTest, ProtectGetPacketIndex) {
EXPECT_TRUE(s1_.SetSend(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
EXPECT_TRUE(s2_.SetReceive(kSrtpAes128CmSha1_80, kTestKey1,
kEncryptedHeaderExtensionIds));
// Buffers include enough room for the 10 byte SRTP auth tag so we can
// encrypt in place.
unsigned char kFrame1[] = {
// clang-format off
// PT=0, SN=65535, TS=0, SSRC=1
0x80, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
0xBE, 0xEF, // data bytes
// Space for the SRTP auth tag
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
// clang-format on
};
rtc::CopyOnWriteBuffer packet1(kFrame1, sizeof(kFrame1) - 10,
sizeof(kFrame1));
unsigned char kFrame2[] = {
// clang-format off
// PT=0, SN=1, TS=0, SSRC=1
0x80, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
0xBE, 0xEF, // data bytes
// Space for the SRTP auth tag
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
// clang-format on
};
rtc::CopyOnWriteBuffer packet2(kFrame2, sizeof(kFrame2) - 10,
sizeof(kFrame1));
// Encrypt the frames in-order. There is a sequence number rollover from
// 65535 to 1 (skipping 0) and the second packet gets encrypted with a
// roll-over counter (ROC) of 1. See
// https://datatracker.ietf.org/doc/html/rfc3711#section-3.3.1
int64_t index;
EXPECT_TRUE(s1_.ProtectRtp(packet1, &index));
EXPECT_EQ(packet1.size(), 24u);
EXPECT_EQ(index, 0xffff00000000); // ntohl(65535 << 16)
EXPECT_TRUE(s1_.ProtectRtp(packet2, &index));
EXPECT_EQ(packet2.size(), 24u);
EXPECT_EQ(index, 0x10001000000); // ntohl(65537 << 16)
}
} // namespace rtc