v4.19.13 snapshot.
diff --git a/tools/testing/selftests/net/udpgso.c b/tools/testing/selftests/net/udpgso.c
new file mode 100644
index 0000000..e279051
--- /dev/null
+++ b/tools/testing/selftests/net/udpgso.c
@@ -0,0 +1,693 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+
+#include <stddef.h>
+#include <arpa/inet.h>
+#include <error.h>
+#include <errno.h>
+#include <net/if.h>
+#include <linux/in.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <netinet/if_ether.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#ifndef ETH_MAX_MTU
+#define ETH_MAX_MTU	0xFFFFU
+#endif
+
+#ifndef UDP_SEGMENT
+#define UDP_SEGMENT		103
+#endif
+
+#ifndef UDP_MAX_SEGMENTS
+#define UDP_MAX_SEGMENTS	(1 << 6UL)
+#endif
+
+#define CONST_MTU_TEST	1500
+
+#define CONST_HDRLEN_V4		(sizeof(struct iphdr) + sizeof(struct udphdr))
+#define CONST_HDRLEN_V6		(sizeof(struct ip6_hdr) + sizeof(struct udphdr))
+
+#define CONST_MSS_V4		(CONST_MTU_TEST - CONST_HDRLEN_V4)
+#define CONST_MSS_V6		(CONST_MTU_TEST - CONST_HDRLEN_V6)
+
+#define CONST_MAX_SEGS_V4	(ETH_MAX_MTU / CONST_MSS_V4)
+#define CONST_MAX_SEGS_V6	(ETH_MAX_MTU / CONST_MSS_V6)
+
+static bool		cfg_do_ipv4;
+static bool		cfg_do_ipv6;
+static bool		cfg_do_connected;
+static bool		cfg_do_connectionless;
+static bool		cfg_do_msgmore;
+static bool		cfg_do_setsockopt;
+static int		cfg_specific_test_id = -1;
+
+static const char	cfg_ifname[] = "lo";
+static unsigned short	cfg_port = 9000;
+
+static char buf[ETH_MAX_MTU];
+
+struct testcase {
+	int tlen;		/* send() buffer size, may exceed mss */
+	bool tfail;		/* send() call is expected to fail */
+	int gso_len;		/* mss after applying gso */
+	int r_num_mss;		/* recv(): number of calls of full mss */
+	int r_len_last;		/* recv(): size of last non-mss dgram, if any */
+};
+
+const struct in6_addr addr6 = IN6ADDR_LOOPBACK_INIT;
+const struct in_addr addr4 = { .s_addr = __constant_htonl(INADDR_LOOPBACK + 2) };
+
+struct testcase testcases_v4[] = {
+	{
+		/* no GSO: send a single byte */
+		.tlen = 1,
+		.r_len_last = 1,
+	},
+	{
+		/* no GSO: send a single MSS */
+		.tlen = CONST_MSS_V4,
+		.r_num_mss = 1,
+	},
+	{
+		/* no GSO: send a single MSS + 1B: fail */
+		.tlen = CONST_MSS_V4 + 1,
+		.tfail = true,
+	},
+	{
+		/* send a single MSS: will fail with GSO, because the segment
+		 * logic in udp4_ufo_fragment demands a gso skb to be > MTU
+		 */
+		.tlen = CONST_MSS_V4,
+		.gso_len = CONST_MSS_V4,
+		.tfail = true,
+		.r_num_mss = 1,
+	},
+	{
+		/* send a single MSS + 1B */
+		.tlen = CONST_MSS_V4 + 1,
+		.gso_len = CONST_MSS_V4,
+		.r_num_mss = 1,
+		.r_len_last = 1,
+	},
+	{
+		/* send exactly 2 MSS */
+		.tlen = CONST_MSS_V4 * 2,
+		.gso_len = CONST_MSS_V4,
+		.r_num_mss = 2,
+	},
+	{
+		/* send 2 MSS + 1B */
+		.tlen = (CONST_MSS_V4 * 2) + 1,
+		.gso_len = CONST_MSS_V4,
+		.r_num_mss = 2,
+		.r_len_last = 1,
+	},
+	{
+		/* send MAX segs */
+		.tlen = (ETH_MAX_MTU / CONST_MSS_V4) * CONST_MSS_V4,
+		.gso_len = CONST_MSS_V4,
+		.r_num_mss = (ETH_MAX_MTU / CONST_MSS_V4),
+	},
+
+	{
+		/* send MAX bytes */
+		.tlen = ETH_MAX_MTU - CONST_HDRLEN_V4,
+		.gso_len = CONST_MSS_V4,
+		.r_num_mss = CONST_MAX_SEGS_V4,
+		.r_len_last = ETH_MAX_MTU - CONST_HDRLEN_V4 -
+			      (CONST_MAX_SEGS_V4 * CONST_MSS_V4),
+	},
+	{
+		/* send MAX + 1: fail */
+		.tlen = ETH_MAX_MTU - CONST_HDRLEN_V4 + 1,
+		.gso_len = CONST_MSS_V4,
+		.tfail = true,
+	},
+	{
+		/* send a single 1B MSS: will fail, see single MSS above */
+		.tlen = 1,
+		.gso_len = 1,
+		.tfail = true,
+		.r_num_mss = 1,
+	},
+	{
+		/* send 2 1B segments */
+		.tlen = 2,
+		.gso_len = 1,
+		.r_num_mss = 2,
+	},
+	{
+		/* send 2B + 2B + 1B segments */
+		.tlen = 5,
+		.gso_len = 2,
+		.r_num_mss = 2,
+		.r_len_last = 1,
+	},
+	{
+		/* send max number of min sized segments */
+		.tlen = UDP_MAX_SEGMENTS - CONST_HDRLEN_V4,
+		.gso_len = 1,
+		.r_num_mss = UDP_MAX_SEGMENTS - CONST_HDRLEN_V4,
+	},
+	{
+		/* send max number + 1 of min sized segments: fail */
+		.tlen = UDP_MAX_SEGMENTS - CONST_HDRLEN_V4 + 1,
+		.gso_len = 1,
+		.tfail = true,
+	},
+	{
+		/* EOL */
+	}
+};
+
+#ifndef IP6_MAX_MTU
+#define IP6_MAX_MTU	(ETH_MAX_MTU + sizeof(struct ip6_hdr))
+#endif
+
+struct testcase testcases_v6[] = {
+	{
+		/* no GSO: send a single byte */
+		.tlen = 1,
+		.r_len_last = 1,
+	},
+	{
+		/* no GSO: send a single MSS */
+		.tlen = CONST_MSS_V6,
+		.r_num_mss = 1,
+	},
+	{
+		/* no GSO: send a single MSS + 1B: fail */
+		.tlen = CONST_MSS_V6 + 1,
+		.tfail = true,
+	},
+	{
+		/* send a single MSS: will fail with GSO, because the segment
+		 * logic in udp4_ufo_fragment demands a gso skb to be > MTU
+		 */
+		.tlen = CONST_MSS_V6,
+		.gso_len = CONST_MSS_V6,
+		.tfail = true,
+		.r_num_mss = 1,
+	},
+	{
+		/* send a single MSS + 1B */
+		.tlen = CONST_MSS_V6 + 1,
+		.gso_len = CONST_MSS_V6,
+		.r_num_mss = 1,
+		.r_len_last = 1,
+	},
+	{
+		/* send exactly 2 MSS */
+		.tlen = CONST_MSS_V6 * 2,
+		.gso_len = CONST_MSS_V6,
+		.r_num_mss = 2,
+	},
+	{
+		/* send 2 MSS + 1B */
+		.tlen = (CONST_MSS_V6 * 2) + 1,
+		.gso_len = CONST_MSS_V6,
+		.r_num_mss = 2,
+		.r_len_last = 1,
+	},
+	{
+		/* send MAX segs */
+		.tlen = (IP6_MAX_MTU / CONST_MSS_V6) * CONST_MSS_V6,
+		.gso_len = CONST_MSS_V6,
+		.r_num_mss = (IP6_MAX_MTU / CONST_MSS_V6),
+	},
+
+	{
+		/* send MAX bytes */
+		.tlen = IP6_MAX_MTU - CONST_HDRLEN_V6,
+		.gso_len = CONST_MSS_V6,
+		.r_num_mss = CONST_MAX_SEGS_V6,
+		.r_len_last = IP6_MAX_MTU - CONST_HDRLEN_V6 -
+			      (CONST_MAX_SEGS_V6 * CONST_MSS_V6),
+	},
+	{
+		/* send MAX + 1: fail */
+		.tlen = IP6_MAX_MTU - CONST_HDRLEN_V6 + 1,
+		.gso_len = CONST_MSS_V6,
+		.tfail = true,
+	},
+	{
+		/* send a single 1B MSS: will fail, see single MSS above */
+		.tlen = 1,
+		.gso_len = 1,
+		.tfail = true,
+		.r_num_mss = 1,
+	},
+	{
+		/* send 2 1B segments */
+		.tlen = 2,
+		.gso_len = 1,
+		.r_num_mss = 2,
+	},
+	{
+		/* send 2B + 2B + 1B segments */
+		.tlen = 5,
+		.gso_len = 2,
+		.r_num_mss = 2,
+		.r_len_last = 1,
+	},
+	{
+		/* send max number of min sized segments */
+		.tlen = UDP_MAX_SEGMENTS - CONST_HDRLEN_V6,
+		.gso_len = 1,
+		.r_num_mss = UDP_MAX_SEGMENTS - CONST_HDRLEN_V6,
+	},
+	{
+		/* send max number + 1 of min sized segments: fail */
+		.tlen = UDP_MAX_SEGMENTS - CONST_HDRLEN_V6 + 1,
+		.gso_len = 1,
+		.tfail = true,
+	},
+	{
+		/* EOL */
+	}
+};
+
+static unsigned int get_device_mtu(int fd, const char *ifname)
+{
+	struct ifreq ifr;
+
+	memset(&ifr, 0, sizeof(ifr));
+
+	strcpy(ifr.ifr_name, ifname);
+
+	if (ioctl(fd, SIOCGIFMTU, &ifr))
+		error(1, errno, "ioctl get mtu");
+
+	return ifr.ifr_mtu;
+}
+
+static void __set_device_mtu(int fd, const char *ifname, unsigned int mtu)
+{
+	struct ifreq ifr;
+
+	memset(&ifr, 0, sizeof(ifr));
+
+	ifr.ifr_mtu = mtu;
+	strcpy(ifr.ifr_name, ifname);
+
+	if (ioctl(fd, SIOCSIFMTU, &ifr))
+		error(1, errno, "ioctl set mtu");
+}
+
+static void set_device_mtu(int fd, int mtu)
+{
+	int val;
+
+	val = get_device_mtu(fd, cfg_ifname);
+	fprintf(stderr, "device mtu (orig): %u\n", val);
+
+	__set_device_mtu(fd, cfg_ifname, mtu);
+	val = get_device_mtu(fd, cfg_ifname);
+	if (val != mtu)
+		error(1, 0, "unable to set device mtu to %u\n", val);
+
+	fprintf(stderr, "device mtu (test): %u\n", val);
+}
+
+static void set_pmtu_discover(int fd, bool is_ipv4)
+{
+	int level, name, val;
+
+	if (is_ipv4) {
+		level	= SOL_IP;
+		name	= IP_MTU_DISCOVER;
+		val	= IP_PMTUDISC_DO;
+	} else {
+		level	= SOL_IPV6;
+		name	= IPV6_MTU_DISCOVER;
+		val	= IPV6_PMTUDISC_DO;
+	}
+
+	if (setsockopt(fd, level, name, &val, sizeof(val)))
+		error(1, errno, "setsockopt path mtu");
+}
+
+static unsigned int get_path_mtu(int fd, bool is_ipv4)
+{
+	socklen_t vallen;
+	unsigned int mtu;
+	int ret;
+
+	vallen = sizeof(mtu);
+	if (is_ipv4)
+		ret = getsockopt(fd, SOL_IP, IP_MTU, &mtu, &vallen);
+	else
+		ret = getsockopt(fd, SOL_IPV6, IPV6_MTU, &mtu, &vallen);
+
+	if (ret)
+		error(1, errno, "getsockopt mtu");
+
+
+	fprintf(stderr, "path mtu (read):  %u\n", mtu);
+	return mtu;
+}
+
+/* very wordy version of system("ip route add dev lo mtu 1500 127.0.0.3/32") */
+static void set_route_mtu(int mtu, bool is_ipv4)
+{
+	struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
+	struct nlmsghdr *nh;
+	struct rtattr *rta;
+	struct rtmsg *rt;
+	char data[NLMSG_ALIGN(sizeof(*nh)) +
+		  NLMSG_ALIGN(sizeof(*rt)) +
+		  NLMSG_ALIGN(RTA_LENGTH(sizeof(addr6))) +
+		  NLMSG_ALIGN(RTA_LENGTH(sizeof(int))) +
+		  NLMSG_ALIGN(RTA_LENGTH(0) + RTA_LENGTH(sizeof(int)))];
+	int fd, ret, alen, off = 0;
+
+	alen = is_ipv4 ? sizeof(addr4) : sizeof(addr6);
+
+	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	if (fd == -1)
+		error(1, errno, "socket netlink");
+
+	memset(data, 0, sizeof(data));
+
+	nh = (void *)data;
+	nh->nlmsg_type = RTM_NEWROUTE;
+	nh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE;
+	off += NLMSG_ALIGN(sizeof(*nh));
+
+	rt = (void *)(data + off);
+	rt->rtm_family = is_ipv4 ? AF_INET : AF_INET6;
+	rt->rtm_table = RT_TABLE_MAIN;
+	rt->rtm_dst_len = alen << 3;
+	rt->rtm_protocol = RTPROT_BOOT;
+	rt->rtm_scope = RT_SCOPE_UNIVERSE;
+	rt->rtm_type = RTN_UNICAST;
+	off += NLMSG_ALIGN(sizeof(*rt));
+
+	rta = (void *)(data + off);
+	rta->rta_type = RTA_DST;
+	rta->rta_len = RTA_LENGTH(alen);
+	if (is_ipv4)
+		memcpy(RTA_DATA(rta), &addr4, alen);
+	else
+		memcpy(RTA_DATA(rta), &addr6, alen);
+	off += NLMSG_ALIGN(rta->rta_len);
+
+	rta = (void *)(data + off);
+	rta->rta_type = RTA_OIF;
+	rta->rta_len = RTA_LENGTH(sizeof(int));
+	*((int *)(RTA_DATA(rta))) = 1; //if_nametoindex("lo");
+	off += NLMSG_ALIGN(rta->rta_len);
+
+	/* MTU is a subtype in a metrics type */
+	rta = (void *)(data + off);
+	rta->rta_type = RTA_METRICS;
+	rta->rta_len = RTA_LENGTH(0) + RTA_LENGTH(sizeof(int));
+	off += NLMSG_ALIGN(rta->rta_len);
+
+	/* now fill MTU subtype. Note that it fits within above rta_len */
+	rta = (void *)(((char *) rta) + RTA_LENGTH(0));
+	rta->rta_type = RTAX_MTU;
+	rta->rta_len = RTA_LENGTH(sizeof(int));
+	*((int *)(RTA_DATA(rta))) = mtu;
+
+	nh->nlmsg_len = off;
+
+	ret = sendto(fd, data, off, 0, (void *)&nladdr, sizeof(nladdr));
+	if (ret != off)
+		error(1, errno, "send netlink: %uB != %uB\n", ret, off);
+
+	if (close(fd))
+		error(1, errno, "close netlink");
+
+	fprintf(stderr, "route mtu (test): %u\n", mtu);
+}
+
+static bool __send_one(int fd, struct msghdr *msg, int flags)
+{
+	int ret;
+
+	ret = sendmsg(fd, msg, flags);
+	if (ret == -1 &&
+	    (errno == EMSGSIZE || errno == ENOMEM || errno == EINVAL))
+		return false;
+	if (ret == -1)
+		error(1, errno, "sendmsg");
+	if (ret != msg->msg_iov->iov_len)
+		error(1, 0, "sendto: %d != %lu", ret, msg->msg_iov->iov_len);
+	if (msg->msg_flags)
+		error(1, 0, "sendmsg: return flags 0x%x\n", msg->msg_flags);
+
+	return true;
+}
+
+static bool send_one(int fd, int len, int gso_len,
+		     struct sockaddr *addr, socklen_t alen)
+{
+	char control[CMSG_SPACE(sizeof(uint16_t))] = {0};
+	struct msghdr msg = {0};
+	struct iovec iov = {0};
+	struct cmsghdr *cm;
+
+	iov.iov_base = buf;
+	iov.iov_len = len;
+
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	msg.msg_name = addr;
+	msg.msg_namelen = alen;
+
+	if (gso_len && !cfg_do_setsockopt) {
+		msg.msg_control = control;
+		msg.msg_controllen = sizeof(control);
+
+		cm = CMSG_FIRSTHDR(&msg);
+		cm->cmsg_level = SOL_UDP;
+		cm->cmsg_type = UDP_SEGMENT;
+		cm->cmsg_len = CMSG_LEN(sizeof(uint16_t));
+		*((uint16_t *) CMSG_DATA(cm)) = gso_len;
+	}
+
+	/* If MSG_MORE, send 1 byte followed by remainder */
+	if (cfg_do_msgmore && len > 1) {
+		iov.iov_len = 1;
+		if (!__send_one(fd, &msg, MSG_MORE))
+			error(1, 0, "send 1B failed");
+
+		iov.iov_base++;
+		iov.iov_len = len - 1;
+	}
+
+	return __send_one(fd, &msg, 0);
+}
+
+static int recv_one(int fd, int flags)
+{
+	int ret;
+
+	ret = recv(fd, buf, sizeof(buf), flags);
+	if (ret == -1 && errno == EAGAIN && (flags & MSG_DONTWAIT))
+		return 0;
+	if (ret == -1)
+		error(1, errno, "recv");
+
+	return ret;
+}
+
+static void run_one(struct testcase *test, int fdt, int fdr,
+		    struct sockaddr *addr, socklen_t alen)
+{
+	int i, ret, val, mss;
+	bool sent;
+
+	fprintf(stderr, "ipv%d tx:%d gso:%d %s\n",
+			addr->sa_family == AF_INET ? 4 : 6,
+			test->tlen, test->gso_len,
+			test->tfail ? "(fail)" : "");
+
+	val = test->gso_len;
+	if (cfg_do_setsockopt) {
+		if (setsockopt(fdt, SOL_UDP, UDP_SEGMENT, &val, sizeof(val)))
+			error(1, errno, "setsockopt udp segment");
+	}
+
+	sent = send_one(fdt, test->tlen, test->gso_len, addr, alen);
+	if (sent && test->tfail)
+		error(1, 0, "send succeeded while expecting failure");
+	if (!sent && !test->tfail)
+		error(1, 0, "send failed while expecting success");
+	if (!sent)
+		return;
+
+	if (test->gso_len)
+		mss = test->gso_len;
+	else
+		mss = addr->sa_family == AF_INET ? CONST_MSS_V4 : CONST_MSS_V6;
+
+
+	/* Recv all full MSS datagrams */
+	for (i = 0; i < test->r_num_mss; i++) {
+		ret = recv_one(fdr, 0);
+		if (ret != mss)
+			error(1, 0, "recv.%d: %d != %d", i, ret, mss);
+	}
+
+	/* Recv the non-full last datagram, if tlen was not a multiple of mss */
+	if (test->r_len_last) {
+		ret = recv_one(fdr, 0);
+		if (ret != test->r_len_last)
+			error(1, 0, "recv.%d: %d != %d (last)",
+			      i, ret, test->r_len_last);
+	}
+
+	/* Verify received all data */
+	ret = recv_one(fdr, MSG_DONTWAIT);
+	if (ret)
+		error(1, 0, "recv: unexpected datagram");
+}
+
+static void run_all(int fdt, int fdr, struct sockaddr *addr, socklen_t alen)
+{
+	struct testcase *tests, *test;
+
+	tests = addr->sa_family == AF_INET ? testcases_v4 : testcases_v6;
+
+	for (test = tests; test->tlen; test++) {
+		/* if a specific test is given, then skip all others */
+		if (cfg_specific_test_id == -1 ||
+		    cfg_specific_test_id == test - tests)
+			run_one(test, fdt, fdr, addr, alen);
+	}
+}
+
+static void run_test(struct sockaddr *addr, socklen_t alen)
+{
+	struct timeval tv = { .tv_usec = 100 * 1000 };
+	int fdr, fdt, val;
+
+	fdr = socket(addr->sa_family, SOCK_DGRAM, 0);
+	if (fdr == -1)
+		error(1, errno, "socket r");
+
+	if (bind(fdr, addr, alen))
+		error(1, errno, "bind");
+
+	/* Have tests fail quickly instead of hang */
+	if (setsockopt(fdr, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)))
+		error(1, errno, "setsockopt rcv timeout");
+
+	fdt = socket(addr->sa_family, SOCK_DGRAM, 0);
+	if (fdt == -1)
+		error(1, errno, "socket t");
+
+	/* Do not fragment these datagrams: only succeed if GSO works */
+	set_pmtu_discover(fdt, addr->sa_family == AF_INET);
+
+	if (cfg_do_connectionless) {
+		set_device_mtu(fdt, CONST_MTU_TEST);
+		run_all(fdt, fdr, addr, alen);
+	}
+
+	if (cfg_do_connected) {
+		set_device_mtu(fdt, CONST_MTU_TEST + 100);
+		set_route_mtu(CONST_MTU_TEST, addr->sa_family == AF_INET);
+
+		if (connect(fdt, addr, alen))
+			error(1, errno, "connect");
+
+		val = get_path_mtu(fdt, addr->sa_family == AF_INET);
+		if (val != CONST_MTU_TEST)
+			error(1, 0, "bad path mtu %u\n", val);
+
+		run_all(fdt, fdr, addr, 0 /* use connected addr */);
+	}
+
+	if (close(fdt))
+		error(1, errno, "close t");
+	if (close(fdr))
+		error(1, errno, "close r");
+}
+
+static void run_test_v4(void)
+{
+	struct sockaddr_in addr = {0};
+
+	addr.sin_family = AF_INET;
+	addr.sin_port = htons(cfg_port);
+	addr.sin_addr = addr4;
+
+	run_test((void *)&addr, sizeof(addr));
+}
+
+static void run_test_v6(void)
+{
+	struct sockaddr_in6 addr = {0};
+
+	addr.sin6_family = AF_INET6;
+	addr.sin6_port = htons(cfg_port);
+	addr.sin6_addr = addr6;
+
+	run_test((void *)&addr, sizeof(addr));
+}
+
+static void parse_opts(int argc, char **argv)
+{
+	int c;
+
+	while ((c = getopt(argc, argv, "46cCmst:")) != -1) {
+		switch (c) {
+		case '4':
+			cfg_do_ipv4 = true;
+			break;
+		case '6':
+			cfg_do_ipv6 = true;
+			break;
+		case 'c':
+			cfg_do_connected = true;
+			break;
+		case 'C':
+			cfg_do_connectionless = true;
+			break;
+		case 'm':
+			cfg_do_msgmore = true;
+			break;
+		case 's':
+			cfg_do_setsockopt = true;
+			break;
+		case 't':
+			cfg_specific_test_id = strtoul(optarg, NULL, 0);
+			break;
+		default:
+			error(1, 0, "%s: parse error", argv[0]);
+		}
+	}
+}
+
+int main(int argc, char **argv)
+{
+	parse_opts(argc, argv);
+
+	if (cfg_do_ipv4)
+		run_test_v4();
+	if (cfg_do_ipv6)
+		run_test_v6();
+
+	fprintf(stderr, "OK\n");
+	return 0;
+}