Ping support via IPv4 raw sockets.

Broadly, this change:
* Enables sockets to be created via `socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)`.
* Passes the network-layer (IP) header up the stack to the transport endpoint,
  which can pass it up to the socket layer. This allows a raw socket to return
  the entire IP packet to users.
* Adds functions to stack.TransportProtocol, stack.Stack, stack.transportDemuxer
  that enable incoming packets to be delivered to raw endpoints. New raw sockets
  of other protocols (not ICMP) just need to register with the stack.
* Enables ping.endpoint to return IP headers when created via SOCK_RAW.

PiperOrigin-RevId: 235993280
Change-Id: I60ed994f5ff18b2cbd79f063a7fdf15d093d845a

2 files changed, 261 insertions, 0 deletions

diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index beece8930..4c818238b 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -1530,6 +1530,22 @@ cc_binary(
 )
 
 cc_binary(
+    name = "raw_socket_ipv4_test",
+    testonly = 1,
+    srcs = ["raw_socket_ipv4.cc"],
+    linkstatic = 1,
+    deps = [
+        ":socket_test_util",
+        "//test/util:capability_util",
+        "//test/util:file_descriptor",
+        "//test/util:test_main",
+        "//test/util:test_util",
+        "@com_google_absl//absl/base:core_headers",
+        "@com_google_googletest//:gtest",
+    ],
+)
+
+cc_binary(
     name = "read_test",
     testonly = 1,
     srcs = ["read.cc"],
diff --git a/test/syscalls/linux/raw_socket_ipv4.cc b/test/syscalls/linux/raw_socket_ipv4.cc
new file mode 100644
index 000000000..c6749321c
--- /dev/null
+++ b/test/syscalls/linux/raw_socket_ipv4.cc
@@ -0,0 +1,245 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <linux/capability.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include "gtest/gtest.h"
+#include "test/syscalls/linux/socket_test_util.h"
+#include "test/util/capability_util.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+// Fixture for tests parameterized by address family (currently only AF_INET).
+class RawSocketTest : public ::testing::Test {
+ protected:
+  // Creates a socket to be used in tests.
+  void SetUp() override;
+
+  // Closes the socket created by SetUp().
+  void TearDown() override;
+
+  // The socket used for both reading and writing.
+  int s_;
+
+  // The loopback address.
+  struct sockaddr_in addr_;
+
+  void sendEmptyICMP(struct icmphdr *icmp);
+
+  void sendEmptyICMPTo(int sock, struct sockaddr_in *addr,
+                       struct icmphdr *icmp);
+
+  void receiveICMP(char *recv_buf, size_t recv_buf_len, size_t expected_size,
+                   struct sockaddr_in *src);
+
+  void receiveICMPFrom(char *recv_buf, size_t recv_buf_len,
+                       size_t expected_size, struct sockaddr_in *src, int sock);
+};
+
+void RawSocketTest::SetUp() {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  ASSERT_THAT(s_ = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP), SyscallSucceeds());
+
+  addr_ = {};
+
+  // We don't set ports because raw sockets don't have a notion of ports.
+  addr_.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+  addr_.sin_family = AF_INET;
+}
+
+void RawSocketTest::TearDown() {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  EXPECT_THAT(close(s_), SyscallSucceeds());
+}
+
+// We should be able to create multiple raw sockets for the same protocol.
+// BasicRawSocket::Setup creates the first one, so we only have to create one
+// more here.
+TEST_F(RawSocketTest, MultipleCreation) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  int s2;
+  ASSERT_THAT(s2 = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP), SyscallSucceeds());
+
+  ASSERT_THAT(close(s2), SyscallSucceeds());
+}
+
+// Send and receive an ICMP packet.
+TEST_F(RawSocketTest, SendAndReceive) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  // Prepare and send an ICMP packet. Use arbitrary junk for checksum, sequence,
+  // and ID. None of that should matter for raw sockets - the kernel should
+  // still give us the packet.
+  struct icmphdr icmp;
+  icmp.type = ICMP_ECHO;
+  icmp.code = 0;
+  icmp.checksum = *(unsigned short *)&icmp.checksum;
+  icmp.un.echo.sequence = *(unsigned short *)&icmp.un.echo.sequence;
+  icmp.un.echo.id = *(unsigned short *)&icmp.un.echo.id;
+  ASSERT_NO_FATAL_FAILURE(sendEmptyICMP(&icmp));
+
+  // Receive the packet and make sure it's identical.
+  char recv_buf[512];
+  struct sockaddr_in src;
+  ASSERT_NO_FATAL_FAILURE(receiveICMP(recv_buf, ABSL_ARRAYSIZE(recv_buf),
+                                      sizeof(struct icmphdr), &src));
+  EXPECT_EQ(memcmp(&src, &addr_, sizeof(sockaddr_in)), 0);
+  EXPECT_EQ(memcmp(recv_buf + sizeof(struct iphdr), &icmp, sizeof(icmp)), 0);
+
+  // We should also receive the automatically generated echo reply.
+  ASSERT_NO_FATAL_FAILURE(receiveICMP(recv_buf, ABSL_ARRAYSIZE(recv_buf),
+                                      sizeof(struct icmphdr), &src));
+  EXPECT_EQ(memcmp(&src, &addr_, sizeof(sockaddr_in)), 0);
+  struct icmphdr *reply_icmp =
+      (struct icmphdr *)(recv_buf + sizeof(struct iphdr));
+  // Most fields should be the same.
+  EXPECT_EQ(reply_icmp->code, icmp.code);
+  EXPECT_EQ(reply_icmp->un.echo.sequence, icmp.un.echo.sequence);
+  EXPECT_EQ(reply_icmp->un.echo.id, icmp.un.echo.id);
+  // A couple are different.
+  EXPECT_EQ(reply_icmp->type, ICMP_ECHOREPLY);
+  // The checksum is computed in such a way that it is guaranteed to have
+  // changed.
+  EXPECT_NE(reply_icmp->checksum, icmp.checksum);
+}
+
+// We should be able to create multiple raw sockets for the same protocol and
+// receive the same packet on both.
+TEST_F(RawSocketTest, MultipleSocketReceive) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  FileDescriptor s2 =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_RAW, IPPROTO_ICMP));
+
+  // Prepare and send an ICMP packet. Use arbitrary junk for checksum, sequence,
+  // and ID. None of that should matter for raw sockets - the kernel should
+  // still give us the packet.
+  struct icmphdr icmp;
+  icmp.type = ICMP_ECHO;
+  icmp.code = 0;
+  icmp.checksum = *(unsigned short *)&icmp.checksum;
+  icmp.un.echo.sequence = *(unsigned short *)&icmp.un.echo.sequence;
+  icmp.un.echo.id = *(unsigned short *)&icmp.un.echo.id;
+  ASSERT_NO_FATAL_FAILURE(sendEmptyICMP(&icmp));
+
+  // Receive it on socket 1.
+  char recv_buf1[512];
+  struct sockaddr_in src;
+  ASSERT_NO_FATAL_FAILURE(receiveICMP(recv_buf1, ABSL_ARRAYSIZE(recv_buf1),
+                                      sizeof(struct icmphdr), &src));
+  EXPECT_EQ(memcmp(&src, &addr_, sizeof(sockaddr_in)), 0);
+
+  // Receive it on socket 2.
+  char recv_buf2[512];
+  ASSERT_NO_FATAL_FAILURE(receiveICMPFrom(recv_buf2, ABSL_ARRAYSIZE(recv_buf2),
+                                          sizeof(struct icmphdr), &src,
+                                          s2.get()));
+  EXPECT_EQ(memcmp(&src, &addr_, sizeof(sockaddr_in)), 0);
+
+  EXPECT_EQ(memcmp(recv_buf1 + sizeof(struct iphdr),
+                   recv_buf2 + sizeof(struct iphdr), sizeof(icmp)),
+            0);
+}
+
+// A raw ICMP socket and ping socket should both receive the ICMP packets
+// indended for the ping socket.
+TEST_F(RawSocketTest, RawAndPingSockets) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  FileDescriptor ping_sock =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP));
+
+  // Ping sockets take care of the ICMP ID and checksum.
+  struct icmphdr icmp;
+  icmp.type = ICMP_ECHO;
+  icmp.code = 0;
+  icmp.un.echo.sequence = *(unsigned short *)&icmp.un.echo.sequence;
+  ASSERT_THAT(RetryEINTR(sendto)(ping_sock.get(), &icmp, sizeof(icmp), 0,
+                                 (struct sockaddr *)&addr_, sizeof(addr_)),
+              SyscallSucceedsWithValue(sizeof(icmp)));
+
+  // Receive the packet via raw socket.
+  char recv_buf[512];
+  struct sockaddr_in src;
+  ASSERT_NO_FATAL_FAILURE(receiveICMP(recv_buf, ABSL_ARRAYSIZE(recv_buf),
+                                      sizeof(struct icmphdr), &src));
+  EXPECT_EQ(memcmp(&src, &addr_, sizeof(sockaddr_in)), 0);
+
+  // Receive the packet via ping socket.
+  struct icmphdr ping_header;
+  ASSERT_THAT(
+      RetryEINTR(recv)(ping_sock.get(), &ping_header, sizeof(ping_header), 0),
+      SyscallSucceedsWithValue(sizeof(ping_header)));
+
+  // Packets should be the same.
+  EXPECT_EQ(memcmp(recv_buf + sizeof(struct iphdr), &ping_header,
+                   sizeof(struct icmphdr)),
+            0);
+}
+
+void RawSocketTest::sendEmptyICMP(struct icmphdr *icmp) {
+  ASSERT_NO_FATAL_FAILURE(sendEmptyICMPTo(s_, &addr_, icmp));
+}
+
+void RawSocketTest::sendEmptyICMPTo(int sock, struct sockaddr_in *addr,
+                                    struct icmphdr *icmp) {
+  struct iovec iov = {.iov_base = icmp, .iov_len = sizeof(*icmp)};
+  struct msghdr msg {
+    .msg_name = addr, .msg_namelen = sizeof(*addr), .msg_iov = &iov,
+    .msg_iovlen = 1, .msg_control = NULL, .msg_controllen = 0, .msg_flags = 0,
+  };
+  ASSERT_THAT(sendmsg(sock, &msg, 0), SyscallSucceedsWithValue(sizeof(*icmp)));
+}
+
+void RawSocketTest::receiveICMP(char *recv_buf, size_t recv_buf_len,
+                                size_t expected_size, struct sockaddr_in *src) {
+  ASSERT_NO_FATAL_FAILURE(
+      receiveICMPFrom(recv_buf, recv_buf_len, expected_size, src, s_));
+}
+
+void RawSocketTest::receiveICMPFrom(char *recv_buf, size_t recv_buf_len,
+                                    size_t expected_size,
+                                    struct sockaddr_in *src, int sock) {
+  struct iovec iov = {.iov_base = recv_buf, .iov_len = recv_buf_len};
+  struct msghdr msg = {
+      .msg_name = src,
+      .msg_namelen = sizeof(*src),
+      .msg_iov = &iov,
+      .msg_iovlen = 1,
+      .msg_control = NULL,
+      .msg_controllen = 0,
+      .msg_flags = 0,
+  };
+  // We should receive the ICMP packet plus 20 bytes of IP header.
+  ASSERT_THAT(recvmsg(sock, &msg, 0),
+              SyscallSucceedsWithValue(expected_size + sizeof(struct iphdr)));
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor