soreuseport: BPF selection functional test

This program will build classic and extended BPF programs and
validate the socket selection logic when used with
SO_ATTACH_REUSEPORT_CBPF and SO_ATTACH_REUSEPORT_EBPF.

It also validates the re-programing flow and several edge cases.
Signed-off-by: Craig Gallek <kraig@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/.gitignore

 socket
 psock_fanout
 psock_tpacket
+reuseport_bpf

tools/testing/selftests/net/Makefile

@@ -4,7 +4,7 @@ CFLAGS = -Wall -O2 -g
 
 CFLAGS += -I../../../../usr/include/
 
-NET_PROGS = socket psock_fanout psock_tpacket
+NET_PROGS = socket psock_fanout psock_tpacket reuseport_bpf
 
 all: $(NET_PROGS)
 %: %.c

tools/testing/selftests/net/reuseport_bpf.c

+/*
+ * Test functionality of BPF filters for SO_REUSEPORT.  The tests below will use
+ * a BPF program (both classic and extended) to read the first word from an
+ * incoming packet (expected to be in network byte-order), calculate a modulus
+ * of that number, and then dispatch the packet to the Nth socket using the
+ * result.  These tests are run for each supported address family and protocol.
+ * Additionally, a few edge cases in the implementation are tested.
+ */
+
+#include <errno.h>
+#include <error.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/unistd.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#endif
+
+struct test_params {
+	int recv_family;
+	int send_family;
+	int protocol;
+	size_t recv_socks;
+	uint16_t recv_port;
+	uint16_t send_port_min;
+};
+
+static size_t sockaddr_size(void)
+{
+	return sizeof(struct sockaddr_storage);
+}
+
+static struct sockaddr *new_any_sockaddr(int family, uint16_t port)
+{
+	struct sockaddr_storage *addr;
+	struct sockaddr_in *addr4;
+	struct sockaddr_in6 *addr6;
+
+	addr = malloc(sizeof(struct sockaddr_storage));
+	memset(addr, 0, sizeof(struct sockaddr_storage));
+
+	switch (family) {
+	case AF_INET:
+		addr4 = (struct sockaddr_in *)addr;
+		addr4->sin_family = AF_INET;
+		addr4->sin_addr.s_addr = htonl(INADDR_ANY);
+		addr4->sin_port = htons(port);
+		break;
+	case AF_INET6:
+		addr6 = (struct sockaddr_in6 *)addr;
+		addr6->sin6_family = AF_INET6;
+		addr6->sin6_addr = in6addr_any;
+		addr6->sin6_port = htons(port);
+		break;
+	default:
+		error(1, 0, "Unsupported family %d", family);
+	}
+	return (struct sockaddr *)addr;
+}
+
+static struct sockaddr *new_loopback_sockaddr(int family, uint16_t port)
+{
+	struct sockaddr *addr = new_any_sockaddr(family, port);
+	struct sockaddr_in *addr4;
+	struct sockaddr_in6 *addr6;
+
+	switch (family) {
+	case AF_INET:
+		addr4 = (struct sockaddr_in *)addr;
+		addr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+		break;
+	case AF_INET6:
+		addr6 = (struct sockaddr_in6 *)addr;
+		addr6->sin6_addr = in6addr_loopback;
+		break;
+	default:
+		error(1, 0, "Unsupported family %d", family);
+	}
+	return addr;
+}
+
+static void attach_ebpf(int fd, uint16_t mod)
+{
+	static char bpf_log_buf[65536];
+	static const char bpf_license[] = "GPL";
+
+	int bpf_fd;
+	const struct bpf_insn prog[] = {
+		/* BPF_MOV64_REG(BPF_REG_6, BPF_REG_1) */
+		{ BPF_ALU64 | BPF_MOV | BPF_X, BPF_REG_6, BPF_REG_1, 0, 0 },
+		/* BPF_LD_ABS(BPF_W, 0) R0 = (uint32_t)skb[0] */
+		{ BPF_LD | BPF_ABS | BPF_W, 0, 0, 0, 0 },
+		/* BPF_ALU64_IMM(BPF_MOD, BPF_REG_0, mod) */
+		{ BPF_ALU64 | BPF_MOD | BPF_K, BPF_REG_0, 0, 0, mod },
+		/* BPF_EXIT_INSN() */
+		{ BPF_JMP | BPF_EXIT, 0, 0, 0, 0 }
+	};
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr.insn_cnt = ARRAY_SIZE(prog);
+	attr.insns = (uint64_t)prog;
+	attr.license = (uint64_t)bpf_license;
+	attr.log_buf = (uint64_t)bpf_log_buf;
+	attr.log_size = sizeof(bpf_log_buf);
+	attr.log_level = 1;
+	attr.kern_version = 0;
+
+	bpf_fd = syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
+	if (bpf_fd < 0)
+		error(1, errno, "ebpf error. log:\n%s\n", bpf_log_buf);
+
+	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_EBPF, &bpf_fd,
+			sizeof(bpf_fd)))
+		error(1, errno, "failed to set SO_ATTACH_REUSEPORT_EBPF");
+}
+
+static void attach_cbpf(int fd, uint16_t mod)
+{
+	struct sock_filter code[] = {
+		/* A = (uint32_t)skb[0] */
+		{ BPF_LD  | BPF_W | BPF_ABS, 0, 0, 0 },
+		/* A = A % mod */
+		{ BPF_ALU | BPF_MOD, 0, 0, mod },
+		/* return A */
+		{ BPF_RET | BPF_A, 0, 0, 0 },
+	};
+	struct sock_fprog p = {
+		.len = ARRAY_SIZE(code),
+		.filter = code,
+	};
+
+	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF, &p, sizeof(p)))
+		error(1, errno, "failed to set SO_ATTACH_REUSEPORT_CBPF");
+}
+
+static void build_recv_group(const struct test_params p, int fd[], uint16_t mod,
+			     void (*attach_bpf)(int, uint16_t))
+{
+	struct sockaddr * const addr =
+		new_any_sockaddr(p.recv_family, p.recv_port);
+	int i, opt;
+
+	for (i = 0; i < p.recv_socks; ++i) {
+		fd[i] = socket(p.recv_family, p.protocol, 0);
+		if (fd[i] < 0)
+			error(1, errno, "failed to create recv %d", i);
+
+		opt = 1;
+		if (setsockopt(fd[i], SOL_SOCKET, SO_REUSEPORT, &opt,
+			       sizeof(opt)))
+			error(1, errno, "failed to set SO_REUSEPORT on %d", i);
+
+		if (i == 0)
+			attach_bpf(fd[i], mod);
+
+		if (bind(fd[i], addr, sockaddr_size()))
+			error(1, errno, "failed to bind recv socket %d", i);
+
+		if (p.protocol == SOCK_STREAM)
+			if (listen(fd[i], p.recv_socks * 10))
+				error(1, errno, "failed to listen on socket");
+	}
+	free(addr);
+}
+
+static void send_from(struct test_params p, uint16_t sport, char *buf,
+		      size_t len)
+{
+	struct sockaddr * const saddr = new_any_sockaddr(p.send_family, sport);
+	struct sockaddr * const daddr =
+		new_loopback_sockaddr(p.send_family, p.recv_port);
+	const int fd = socket(p.send_family, p.protocol, 0);
+
+	if (fd < 0)
+		error(1, errno, "failed to create send socket");
+
+	if (bind(fd, saddr, sockaddr_size()))
+		error(1, errno, "failed to bind send socket");
+	if (connect(fd, daddr, sockaddr_size()))
+		error(1, errno, "failed to connect");
+
+	if (send(fd, buf, len, 0) < 0)
+		error(1, errno, "failed to send message");
+
+	close(fd);
+	free(saddr);
+	free(daddr);
+}
+
+static void test_recv_order(const struct test_params p, int fd[], int mod)
+{
+	char recv_buf[8], send_buf[8];
+	struct msghdr msg;
+	struct iovec recv_io = { recv_buf, 8 };
+	struct epoll_event ev;
+	int epfd, conn, i, sport, expected;
+	uint32_t data, ndata;
+
+	epfd = epoll_create(1);
+	if (epfd < 0)
+		error(1, errno, "failed to create epoll");
+	for (i = 0; i < p.recv_socks; ++i) {
+		ev.events = EPOLLIN;
+		ev.data.fd = fd[i];
+		if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd[i], &ev))
+			error(1, errno, "failed to register sock %d epoll", i);
+	}
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_iov = &recv_io;
+	msg.msg_iovlen = 1;
+
+	for (data = 0; data < p.recv_socks * 2; ++data) {
+		sport = p.send_port_min + data;
+		ndata = htonl(data);
+		memcpy(send_buf, &ndata, sizeof(ndata));
+		send_from(p, sport, send_buf, sizeof(ndata));
+
+		i = epoll_wait(epfd, &ev, 1, -1);
+		if (i < 0)
+			error(1, errno, "epoll wait failed");
+
+		if (p.protocol == SOCK_STREAM) {
+			conn = accept(ev.data.fd, NULL, NULL);
+			if (conn < 0)
+				error(1, errno, "error accepting");
+			i = recvmsg(conn, &msg, 0);
+			close(conn);
+		} else {
+			i = recvmsg(ev.data.fd, &msg, 0);
+		}
+		if (i < 0)
+			error(1, errno, "recvmsg error");
+		if (i != sizeof(ndata))
+			error(1, 0, "expected size %zd got %d",
+			      sizeof(ndata), i);
+
+		for (i = 0; i < p.recv_socks; ++i)
+			if (ev.data.fd == fd[i])
+				break;
+		memcpy(&ndata, recv_buf, sizeof(ndata));
+		fprintf(stderr, "Socket %d: %d\n", i, ntohl(ndata));
+
+		expected = (sport % mod);
+		if (i != expected)
+			error(1, 0, "expected socket %d", expected);
+	}
+}
+
+static void test_reuseport_ebpf(const struct test_params p)
+{
+	int i, fd[p.recv_socks];
+
+	fprintf(stderr, "Testing EBPF mod %zd...\n", p.recv_socks);
+	build_recv_group(p, fd, p.recv_socks, attach_ebpf);
+	test_recv_order(p, fd, p.recv_socks);
+
+	fprintf(stderr, "Reprograming, testing mod %zd...\n", p.recv_socks / 2);
+	attach_ebpf(fd[0], p.recv_socks / 2);
+	test_recv_order(p, fd, p.recv_socks / 2);
+
+	for (i = 0; i < p.recv_socks; ++i)
+		close(fd[i]);
+}
+
+static void test_reuseport_cbpf(const struct test_params p)
+{
+	int i, fd[p.recv_socks];
+
+	fprintf(stderr, "Testing CBPF mod %zd...\n", p.recv_socks);
+	build_recv_group(p, fd, p.recv_socks, attach_cbpf);
+	test_recv_order(p, fd, p.recv_socks);
+
+	fprintf(stderr, "Reprograming, testing mod %zd...\n", p.recv_socks / 2);
+	attach_cbpf(fd[0], p.recv_socks / 2);
+	test_recv_order(p, fd, p.recv_socks / 2);
+
+	for (i = 0; i < p.recv_socks; ++i)
+		close(fd[i]);
+}
+
+static void test_extra_filter(const struct test_params p)
+{
+	struct sockaddr * const addr =
+		new_any_sockaddr(p.recv_family, p.recv_port);
+	int fd1, fd2, opt;
+
+	fprintf(stderr, "Testing too many filters...\n");
+	fd1 = socket(p.recv_family, p.protocol, 0);
+	if (fd1 < 0)
+		error(1, errno, "failed to create socket 1");
+	fd2 = socket(p.recv_family, p.protocol, 0);
+	if (fd2 < 0)
+		error(1, errno, "failed to create socket 2");
+
+	opt = 1;
+	if (setsockopt(fd1, SOL_SOCKET, SO_REUSEPORT, &opt, sizeof(opt)))
+		error(1, errno, "failed to set SO_REUSEPORT on socket 1");
+	if (setsockopt(fd2, SOL_SOCKET, SO_REUSEPORT, &opt, sizeof(opt)))
+		error(1, errno, "failed to set SO_REUSEPORT on socket 2");
+
+	attach_ebpf(fd1, 10);
+	attach_ebpf(fd2, 10);
+
+	if (bind(fd1, addr, sockaddr_size()))
+		error(1, errno, "failed to bind recv socket 1");
+
+	if (!bind(fd2, addr, sockaddr_size()) && errno != EADDRINUSE)
+		error(1, errno, "bind socket 2 should fail with EADDRINUSE");
+
+	free(addr);
+}
+
+static void test_filter_no_reuseport(const struct test_params p)
+{
+	struct sockaddr * const addr =
+		new_any_sockaddr(p.recv_family, p.recv_port);
+	const char bpf_license[] = "GPL";
+	struct bpf_insn ecode[] = {
+		{ BPF_ALU64 | BPF_MOV | BPF_K, BPF_REG_0, 0, 0, 10 },
+		{ BPF_JMP | BPF_EXIT, 0, 0, 0, 0 }
+	};
+	struct sock_filter ccode[] = {{ BPF_RET | BPF_A, 0, 0, 0 }};
+	union bpf_attr eprog;
+	struct sock_fprog cprog;
+	int fd, bpf_fd;
+
+	fprintf(stderr, "Testing filters on non-SO_REUSEPORT socket...\n");
+
+	memset(&eprog, 0, sizeof(eprog));
+	eprog.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	eprog.insn_cnt = ARRAY_SIZE(ecode);
+	eprog.insns = (uint64_t)ecode;
+	eprog.license = (uint64_t)bpf_license;
+	eprog.kern_version = 0;
+
+	memset(&cprog, 0, sizeof(cprog));
+	cprog.len = ARRAY_SIZE(ccode);
+	cprog.filter = ccode;
+
+
+	bpf_fd = syscall(__NR_bpf, BPF_PROG_LOAD, &eprog, sizeof(eprog));
+	if (bpf_fd < 0)
+		error(1, errno, "ebpf error");
+	fd = socket(p.recv_family, p.protocol, 0);
+	if (fd < 0)
+		error(1, errno, "failed to create socket 1");
+
+	if (bind(fd, addr, sockaddr_size()))
+		error(1, errno, "failed to bind recv socket 1");
+
+	errno = 0;
+	if (!setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_EBPF, &bpf_fd,
+			sizeof(bpf_fd)) || errno != EINVAL)
+		error(1, errno, "setsockopt should have returned EINVAL");
+
+	errno = 0;
+	if (!setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF, &cprog,
+		       sizeof(cprog)) || errno != EINVAL)
+		error(1, errno, "setsockopt should have returned EINVAL");
+
+	free(addr);
+}
+
+static void test_filter_without_bind(void)
+{
+	int fd1, fd2;
+
+	fprintf(stderr, "Testing filter add without bind...\n");
+	fd1 = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd1 < 0)
+		error(1, errno, "failed to create socket 1");
+	fd2 = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd2 < 0)
+		error(1, errno, "failed to create socket 2");
+
+	attach_ebpf(fd1, 10);
+	attach_cbpf(fd2, 10);
+
+	close(fd1);
+	close(fd2);
+}
+
+
+int main(void)
+{
+	fprintf(stderr, "---- IPv4 UDP ----\n");
+	test_reuseport_ebpf((struct test_params) {
+		.recv_family = AF_INET,
+		.send_family = AF_INET,
+		.protocol = SOCK_DGRAM,
+		.recv_socks = 10,
+		.recv_port = 8000,
+		.send_port_min = 9000});
+	test_reuseport_cbpf((struct test_params) {
+		.recv_family = AF_INET,
+		.send_family = AF_INET,
+		.protocol = SOCK_DGRAM,
+		.recv_socks = 10,
+		.recv_port = 8001,
+		.send_port_min = 9020});
+	test_extra_filter((struct test_params) {
+		.recv_family = AF_INET,
+		.protocol = SOCK_DGRAM,
+		.recv_port = 8002});
+	test_filter_no_reuseport((struct test_params) {
+		.recv_family = AF_INET,
+		.protocol = SOCK_DGRAM,
+		.recv_port = 8008});
+
+	fprintf(stderr, "---- IPv6 UDP ----\n");
+	test_reuseport_ebpf((struct test_params) {
+		.recv_family = AF_INET6,
+		.send_family = AF_INET6,
+		.protocol = SOCK_DGRAM,
+		.recv_socks = 10,
+		.recv_port = 8003,
+		.send_port_min = 9040});
+	test_reuseport_cbpf((struct test_params) {
+		.recv_family = AF_INET6,
+		.send_family = AF_INET6,
+		.protocol = SOCK_DGRAM,
+		.recv_socks = 10,
+		.recv_port = 8004,
+		.send_port_min = 9060});
+	test_extra_filter((struct test_params) {
+		.recv_family = AF_INET6,
+		.protocol = SOCK_DGRAM,
+		.recv_port = 8005});
+	test_filter_no_reuseport((struct test_params) {
+		.recv_family = AF_INET6,
+		.protocol = SOCK_DGRAM,
+		.recv_port = 8009});
+
+	fprintf(stderr, "---- IPv6 UDP w/ mapped IPv4 ----\n");
+	test_reuseport_ebpf((struct test_params) {
+		.recv_family = AF_INET6,
+		.send_family = AF_INET,
+		.protocol = SOCK_DGRAM,
+		.recv_socks = 10,
+		.recv_port = 8006,
+		.send_port_min = 9080});
+	test_reuseport_cbpf((struct test_params) {
+		.recv_family = AF_INET6,
+		.send_family = AF_INET,
+		.protocol = SOCK_DGRAM,
+		.recv_socks = 10,
+		.recv_port = 8007,
+		.send_port_min = 9100});
+
+
+	test_filter_without_bind();
+
+	fprintf(stderr, "SUCCESS\n");
+	return 0;
+}