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gvisor/test/syscalls/linux/packet_socket.cc

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// Copyright 2019 The gVisor Authors.
//
// 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 <arpa/inet.h>
#include <ifaddrs.h>
#include <linux/capability.h>
#include <linux/if_arp.h>
#include <linux/if_packet.h>
#include <net/ethernet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include "gtest/gtest.h"
#include "absl/base/internal/endian.h"
#include "test/syscalls/linux/socket_test_util.h"
#include "test/syscalls/linux/unix_domain_socket_test_util.h"
#include "test/util/capability_util.h"
#include "test/util/file_descriptor.h"
#include "test/util/test_util.h"
// Some of these tests involve sending packets via AF_PACKET sockets and the
// loopback interface. Because AF_PACKET circumvents so much of the networking
// stack, Linux sees these packets as "martian", i.e. they claim to be to/from
// localhost but don't have the usual associated data. Thus Linux drops them by
// default. You can see where this happens by following the code at:
//
// - net/ipv4/ip_input.c:ip_rcv_finish, which calls
// - net/ipv4/route.c:ip_route_input_noref, which calls
// - net/ipv4/route.c:ip_route_input_slow, which finds and drops martian
// packets.
//
// To tell Linux not to drop these packets, you need to tell it to accept our
// funny packets (which are completely valid and correct, but lack associated
// in-kernel data because we use AF_PACKET):
//
// echo 1 >> /proc/sys/net/ipv4/conf/lo/accept_local
// echo 1 >> /proc/sys/net/ipv4/conf/lo/route_localnet
//
// These tests require CAP_NET_RAW to run.
// TODO(gvisor.dev/issue/173): gVisor support.
namespace gvisor {
namespace testing {
namespace {
using ::testing::AnyOf;
using ::testing::Eq;
constexpr char kMessage[] = "soweoneul malhaebwa";
constexpr in_port_t kPort = 0x409c; // htons(40000)
//
// "Cooked" tests. Cooked AF_PACKET sockets do not contain link layer
// headers, and provide link layer destination/source information via a
// returned struct sockaddr_ll.
//
// Send kMessage via sock to loopback
void SendUDPMessage(int sock) {
struct sockaddr_in dest = {};
dest.sin_port = kPort;
dest.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
dest.sin_family = AF_INET;
EXPECT_THAT(sendto(sock, kMessage, sizeof(kMessage), 0,
reinterpret_cast<struct sockaddr*>(&dest), sizeof(dest)),
SyscallSucceedsWithValue(sizeof(kMessage)));
}
// Send an IP packet and make sure ETH_P_<something else> doesn't pick it up.
TEST(BasicCookedPacketTest, WrongType) {
if (!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW))) {
ASSERT_THAT(socket(AF_PACKET, SOCK_DGRAM, ETH_P_PUP),
SyscallFailsWithErrno(EPERM));
GTEST_SKIP();
}
FileDescriptor sock = ASSERT_NO_ERRNO_AND_VALUE(
Socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_PUP)));
// Let's use a simple IP payload: a UDP datagram.
FileDescriptor udp_sock =
ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_DGRAM, 0));
SendUDPMessage(udp_sock.get());
// Wait and make sure the socket never becomes readable.
struct pollfd pfd = {};
pfd.fd = sock.get();
pfd.events = POLLIN;
EXPECT_THAT(RetryEINTR(poll)(&pfd, 1, 1000), SyscallSucceedsWithValue(0));
}
// Tests for "cooked" (SOCK_DGRAM) packet(7) sockets.
class CookedPacketTest : public ::testing::TestWithParam<int> {
protected:
// Creates a socket to be used in tests.
void SetUp() override;
// Closes the socket created by SetUp().
void TearDown() override;
// Gets the device index of the loopback device.
int GetLoopbackIndex();
// The socket used for both reading and writing.
int socket_;
};
void CookedPacketTest::SetUp() {
if (!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW))) {
ASSERT_THAT(socket(AF_PACKET, SOCK_DGRAM, htons(GetParam())),
SyscallFailsWithErrno(EPERM));
GTEST_SKIP();
}
if (!IsRunningOnGvisor()) {
FileDescriptor acceptLocal = ASSERT_NO_ERRNO_AND_VALUE(
Open("/proc/sys/net/ipv4/conf/lo/accept_local", O_RDONLY));
FileDescriptor routeLocalnet = ASSERT_NO_ERRNO_AND_VALUE(
Open("/proc/sys/net/ipv4/conf/lo/route_localnet", O_RDONLY));
char enabled;
ASSERT_THAT(read(acceptLocal.get(), &enabled, 1),
SyscallSucceedsWithValue(1));
ASSERT_EQ(enabled, '1');
ASSERT_THAT(read(routeLocalnet.get(), &enabled, 1),
SyscallSucceedsWithValue(1));
ASSERT_EQ(enabled, '1');
}
ASSERT_THAT(socket_ = socket(AF_PACKET, SOCK_DGRAM, htons(GetParam())),
SyscallSucceeds());
}
void CookedPacketTest::TearDown() {
// TearDown will be run even if we skip the test.
if (ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW))) {
EXPECT_THAT(close(socket_), SyscallSucceeds());
}
}
int CookedPacketTest::GetLoopbackIndex() {
struct ifreq ifr;
snprintf(ifr.ifr_name, IFNAMSIZ, "lo");
EXPECT_THAT(ioctl(socket_, SIOCGIFINDEX, &ifr), SyscallSucceeds());
EXPECT_NE(ifr.ifr_ifindex, 0);
return ifr.ifr_ifindex;
}
// Receive and verify the message via packet socket on interface.
void ReceiveMessage(int sock, int ifindex) {
// Wait for the socket to become readable.
struct pollfd pfd = {};
pfd.fd = sock;
pfd.events = POLLIN;
EXPECT_THAT(RetryEINTR(poll)(&pfd, 1, 2000), SyscallSucceedsWithValue(1));
// Read and verify the data.
constexpr size_t packet_size =
sizeof(struct iphdr) + sizeof(struct udphdr) + sizeof(kMessage);
char buf[64];
struct sockaddr_ll src = {};
socklen_t src_len = sizeof(src);
ASSERT_THAT(recvfrom(sock, buf, sizeof(buf), 0,
reinterpret_cast<struct sockaddr*>(&src), &src_len),
SyscallSucceedsWithValue(packet_size));
// sockaddr_ll ends with an 8 byte physical address field, but ethernet
// addresses only use 6 bytes. Linux used to return sizeof(sockaddr_ll)-2
// here, but since commit b2cf86e1563e33a14a1c69b3e508d15dc12f804c returns
// sizeof(sockaddr_ll).
ASSERT_THAT(src_len, AnyOf(Eq(sizeof(src)), Eq(sizeof(src) - 2)));
// TODO(b/129292371): Verify protocol once we return it.
// Verify the source address.
EXPECT_EQ(src.sll_family, AF_PACKET);
EXPECT_EQ(src.sll_ifindex, ifindex);
EXPECT_EQ(src.sll_halen, ETH_ALEN);
// This came from the loopback device, so the address is all 0s.
for (int i = 0; i < src.sll_halen; i++) {
EXPECT_EQ(src.sll_addr[i], 0);
}
// Verify the IP header. We memcpy to deal with pointer aligment.
struct iphdr ip = {};
memcpy(&ip, buf, sizeof(ip));
EXPECT_EQ(ip.ihl, 5);
EXPECT_EQ(ip.version, 4);
EXPECT_EQ(ip.tot_len, htons(packet_size));
EXPECT_EQ(ip.protocol, IPPROTO_UDP);
EXPECT_EQ(ip.daddr, htonl(INADDR_LOOPBACK));
EXPECT_EQ(ip.saddr, htonl(INADDR_LOOPBACK));
// Verify the UDP header. We memcpy to deal with pointer aligment.
struct udphdr udp = {};
memcpy(&udp, buf + sizeof(iphdr), sizeof(udp));
EXPECT_EQ(udp.dest, kPort);
EXPECT_EQ(udp.len, htons(sizeof(udphdr) + sizeof(kMessage)));
// Verify the payload.
char* payload = reinterpret_cast<char*>(buf + sizeof(iphdr) + sizeof(udphdr));
EXPECT_EQ(strncmp(payload, kMessage, sizeof(kMessage)), 0);
}
// Receive via a packet socket.
TEST_P(CookedPacketTest, Receive) {
// Let's use a simple IP payload: a UDP datagram.
FileDescriptor udp_sock =
ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_DGRAM, 0));
SendUDPMessage(udp_sock.get());
// Receive and verify the data.
int loopback_index = GetLoopbackIndex();
ReceiveMessage(socket_, loopback_index);
}
// Send via a packet socket.
TEST_P(CookedPacketTest, Send) {
// TODO(b/129292371): Remove once we support packet socket writing.
SKIP_IF(IsRunningOnGvisor());
// Let's send a UDP packet and receive it using a regular UDP socket.
FileDescriptor udp_sock =
ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_DGRAM, 0));
struct sockaddr_in bind_addr = {};
bind_addr.sin_family = AF_INET;
bind_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
bind_addr.sin_port = kPort;
ASSERT_THAT(
bind(udp_sock.get(), reinterpret_cast<struct sockaddr*>(&bind_addr),
sizeof(bind_addr)),
SyscallSucceeds());
// Set up the destination physical address.
struct sockaddr_ll dest = {};
dest.sll_family = AF_PACKET;
dest.sll_halen = ETH_ALEN;
dest.sll_ifindex = GetLoopbackIndex();
dest.sll_protocol = htons(ETH_P_IP);
// We're sending to the loopback device, so the address is all 0s.
memset(dest.sll_addr, 0x00, ETH_ALEN);
// Set up the IP header.
struct iphdr iphdr = {0};
iphdr.ihl = 5;
iphdr.version = 4;
iphdr.tos = 0;
iphdr.tot_len =
htons(sizeof(struct iphdr) + sizeof(struct udphdr) + sizeof(kMessage));
// Get a pseudo-random ID. If we clash with an in-use ID the test will fail,
// but we have no way of getting an ID we know to be good.
srand(*reinterpret_cast<unsigned int*>(&iphdr));
iphdr.id = rand();
// Linux sets this bit ("do not fragment") for small packets.
iphdr.frag_off = 1 << 6;
iphdr.ttl = 64;
iphdr.protocol = IPPROTO_UDP;
iphdr.daddr = htonl(INADDR_LOOPBACK);
iphdr.saddr = htonl(INADDR_LOOPBACK);
iphdr.check = IPChecksum(iphdr);
// Set up the UDP header.
struct udphdr udphdr = {};
udphdr.source = kPort;
udphdr.dest = kPort;
udphdr.len = htons(sizeof(udphdr) + sizeof(kMessage));
udphdr.check = UDPChecksum(iphdr, udphdr, kMessage, sizeof(kMessage));
// Copy both headers and the payload into our packet buffer.
char send_buf[sizeof(iphdr) + sizeof(udphdr) + sizeof(kMessage)];
memcpy(send_buf, &iphdr, sizeof(iphdr));
memcpy(send_buf + sizeof(iphdr), &udphdr, sizeof(udphdr));
memcpy(send_buf + sizeof(iphdr) + sizeof(udphdr), kMessage, sizeof(kMessage));
// Send it.
ASSERT_THAT(sendto(socket_, send_buf, sizeof(send_buf), 0,
reinterpret_cast<struct sockaddr*>(&dest), sizeof(dest)),
SyscallSucceedsWithValue(sizeof(send_buf)));
// Wait for the packet to become available on both sockets.
struct pollfd pfd = {};
pfd.fd = udp_sock.get();
pfd.events = POLLIN;
ASSERT_THAT(RetryEINTR(poll)(&pfd, 1, 5000), SyscallSucceedsWithValue(1));
pfd.fd = socket_;
pfd.events = POLLIN;
ASSERT_THAT(RetryEINTR(poll)(&pfd, 1, 5000), SyscallSucceedsWithValue(1));
// Receive on the packet socket.
char recv_buf[sizeof(send_buf)];
ASSERT_THAT(recv(socket_, recv_buf, sizeof(recv_buf), 0),
SyscallSucceedsWithValue(sizeof(recv_buf)));
ASSERT_EQ(memcmp(recv_buf, send_buf, sizeof(send_buf)), 0);
// Receive on the UDP socket.
struct sockaddr_in src;
socklen_t src_len = sizeof(src);
ASSERT_THAT(recvfrom(udp_sock.get(), recv_buf, sizeof(recv_buf), MSG_DONTWAIT,
reinterpret_cast<struct sockaddr*>(&src), &src_len),
SyscallSucceedsWithValue(sizeof(kMessage)));
// Check src and payload.
EXPECT_EQ(strncmp(recv_buf, kMessage, sizeof(kMessage)), 0);
EXPECT_EQ(src.sin_family, AF_INET);
EXPECT_EQ(src.sin_port, kPort);
EXPECT_EQ(src.sin_addr.s_addr, htonl(INADDR_LOOPBACK));
}
// Bind and receive via packet socket.
TEST_P(CookedPacketTest, BindReceive) {
struct sockaddr_ll bind_addr = {};
bind_addr.sll_family = AF_PACKET;
bind_addr.sll_protocol = htons(GetParam());
bind_addr.sll_ifindex = GetLoopbackIndex();
ASSERT_THAT(bind(socket_, reinterpret_cast<struct sockaddr*>(&bind_addr),
sizeof(bind_addr)),
SyscallSucceeds());
// Let's use a simple IP payload: a UDP datagram.
FileDescriptor udp_sock =
ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_DGRAM, 0));
SendUDPMessage(udp_sock.get());
// Receive and verify the data.
ReceiveMessage(socket_, bind_addr.sll_ifindex);
}
// Double Bind socket.
TEST_P(CookedPacketTest, DoubleBind) {
struct sockaddr_ll bind_addr = {};
bind_addr.sll_family = AF_PACKET;
bind_addr.sll_protocol = htons(GetParam());
bind_addr.sll_ifindex = GetLoopbackIndex();
ASSERT_THAT(bind(socket_, reinterpret_cast<struct sockaddr*>(&bind_addr),
sizeof(bind_addr)),
SyscallSucceeds());
// Binding socket again should fail.
ASSERT_THAT(
bind(socket_, reinterpret_cast<struct sockaddr*>(&bind_addr),
sizeof(bind_addr)),
// Linux 4.09 returns EINVAL here, but some time before 4.19 it switched
// to EADDRINUSE.
AnyOf(SyscallFailsWithErrno(EADDRINUSE), SyscallFailsWithErrno(EINVAL)));
}
// Bind and verify we do not receive data on interface which is not bound
TEST_P(CookedPacketTest, BindDrop) {
// Let's use a simple IP payload: a UDP datagram.
FileDescriptor udp_sock =
ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET, SOCK_DGRAM, 0));
struct ifaddrs* if_addr_list = nullptr;
auto cleanup = Cleanup([&if_addr_list]() { freeifaddrs(if_addr_list); });
ASSERT_THAT(getifaddrs(&if_addr_list), SyscallSucceeds());
// Get interface other than loopback.
struct ifreq ifr = {};
for (struct ifaddrs* i = if_addr_list; i; i = i->ifa_next) {
if (strcmp(i->ifa_name, "lo") != 0) {
strncpy(ifr.ifr_name, i->ifa_name, sizeof(ifr.ifr_name));
break;
}
}
// Skip if no interface is available other than loopback.
if (strlen(ifr.ifr_name) == 0) {
GTEST_SKIP();
}
// Get interface index.
EXPECT_THAT(ioctl(socket_, SIOCGIFINDEX, &ifr), SyscallSucceeds());
EXPECT_NE(ifr.ifr_ifindex, 0);
// Bind to packet socket requires only family, protocol and ifindex.
struct sockaddr_ll bind_addr = {};
bind_addr.sll_family = AF_PACKET;
bind_addr.sll_protocol = htons(GetParam());
bind_addr.sll_ifindex = ifr.ifr_ifindex;
ASSERT_THAT(bind(socket_, reinterpret_cast<struct sockaddr*>(&bind_addr),
sizeof(bind_addr)),
SyscallSucceeds());
// Send to loopback interface.
struct sockaddr_in dest = {};
dest.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
dest.sin_family = AF_INET;
dest.sin_port = kPort;
EXPECT_THAT(sendto(udp_sock.get(), kMessage, sizeof(kMessage), 0,
reinterpret_cast<struct sockaddr*>(&dest), sizeof(dest)),
SyscallSucceedsWithValue(sizeof(kMessage)));
// Wait and make sure the socket never receives any data.
struct pollfd pfd = {};
pfd.fd = socket_;
pfd.events = POLLIN;
EXPECT_THAT(RetryEINTR(poll)(&pfd, 1, 1000), SyscallSucceedsWithValue(0));
}
// Bind with invalid address.
TEST_P(CookedPacketTest, BindFail) {
// Null address.
ASSERT_THAT(
bind(socket_, nullptr, sizeof(struct sockaddr)),
AnyOf(SyscallFailsWithErrno(EFAULT), SyscallFailsWithErrno(EINVAL)));
// Address of size 1.
uint8_t addr = 0;
ASSERT_THAT(
bind(socket_, reinterpret_cast<struct sockaddr*>(&addr), sizeof(addr)),
SyscallFailsWithErrno(EINVAL));
}
INSTANTIATE_TEST_SUITE_P(AllInetTests, CookedPacketTest,
::testing::Values(ETH_P_IP, ETH_P_ALL));
} // namespace
} // namespace testing
} // namespace gvisor
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