Commit 12d8bb64 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

bpf: xdp: Add XDP example for head adjustment 



The XDP prog checks if the incoming packet matches any VIP:PORT
combination in the BPF hashmap.  If it is, it will encapsulate
the packet with a IPv4/v6 header as instructed by the value of
the BPF hashmap and then XDP_TX it out.

The VIP:PORT -> IP-Encap-Info can be specified by the cmd args
of the user prog.

Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ea3349a0

samples/bpf/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ hostprogs-y += trace_event 
hostprogs-y += sampleip

hostprogs-y += tc_l2_redirect

hostprogs-y += lwt_len_hist

hostprogs-y += xdp_tx_iptunnel



test_lru_dist-objs := test_lru_dist.o libbpf.o

sock_example-objs := sock_example.o libbpf.o
@@ -67,6 +68,7 @@ trace_event-objs := bpf_load.o libbpf.o trace_event_user.o 
sampleip-objs := bpf_load.o libbpf.o sampleip_user.o

tc_l2_redirect-objs := bpf_load.o libbpf.o tc_l2_redirect_user.o

lwt_len_hist-objs := bpf_load.o libbpf.o lwt_len_hist_user.o

xdp_tx_iptunnel-objs := bpf_load.o libbpf.o xdp_tx_iptunnel_user.o



# Tell kbuild to always build the programs

always := $(hostprogs-y)
@@ -99,6 +101,7 @@ always += test_current_task_under_cgroup_kern.o 
always += trace_event_kern.o

always += sampleip_kern.o

always += lwt_len_hist_kern.o

always += xdp_tx_iptunnel_kern.o



HOSTCFLAGS += -I$(objtree)/usr/include

HOSTCFLAGS += -I$(srctree)/tools/testing/selftests/bpf/
@@ -129,6 +132,7 @@ HOSTLOADLIBES_trace_event += -lelf 
HOSTLOADLIBES_sampleip += -lelf

HOSTLOADLIBES_tc_l2_redirect += -l elf

HOSTLOADLIBES_lwt_len_hist += -l elf

HOSTLOADLIBES_xdp_tx_iptunnel += -lelf



# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:

#  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang

samples/bpf/bpf_helpers.h

+2 −0
Original line number Diff line number Diff line
@@ -57,6 +57,8 @@ static int (*bpf_skb_set_tunnel_opt)(void *ctx, void *md, int size) = 
	(void *) BPF_FUNC_skb_set_tunnel_opt;

static unsigned long long (*bpf_get_prandom_u32)(void) =

	(void *) BPF_FUNC_get_prandom_u32;

static int (*bpf_xdp_adjust_head)(void *ctx, int offset) =

	(void *) BPF_FUNC_xdp_adjust_head;



/* llvm builtin functions that eBPF C program may use to

 * emit BPF_LD_ABS and BPF_LD_IND instructions

samples/bpf/bpf_load.c

+94 −0
Original line number Diff line number Diff line
@@ -12,6 +12,10 @@ 
#include <linux/bpf.h>

#include <linux/filter.h>

#include <linux/perf_event.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/syscall.h>

#include <sys/ioctl.h>

#include <sys/mman.h>
@@ -450,3 +454,93 @@ struct ksym *ksym_search(long key) 
	/* out of range. return _stext */

	return &syms[0];

}



int set_link_xdp_fd(int ifindex, int fd)

{

	struct sockaddr_nl sa;

	int sock, seq = 0, len, ret = -1;

	char buf[4096];

	struct nlattr *nla, *nla_xdp;

	struct {

		struct nlmsghdr  nh;

		struct ifinfomsg ifinfo;

		char             attrbuf[64];

	} req;

	struct nlmsghdr *nh;

	struct nlmsgerr *err;



	memset(&sa, 0, sizeof(sa));

	sa.nl_family = AF_NETLINK;



	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);

	if (sock < 0) {

		printf("open netlink socket: %s\n", strerror(errno));

		return -1;

	}



	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {

		printf("bind to netlink: %s\n", strerror(errno));

		goto cleanup;

	}



	memset(&req, 0, sizeof(req));

	req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));

	req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;

	req.nh.nlmsg_type = RTM_SETLINK;

	req.nh.nlmsg_pid = 0;

	req.nh.nlmsg_seq = ++seq;

	req.ifinfo.ifi_family = AF_UNSPEC;

	req.ifinfo.ifi_index = ifindex;

	nla = (struct nlattr *)(((char *)&req)

				+ NLMSG_ALIGN(req.nh.nlmsg_len));

	nla->nla_type = NLA_F_NESTED | 43/*IFLA_XDP*/;



	nla_xdp = (struct nlattr *)((char *)nla + NLA_HDRLEN);

	nla_xdp->nla_type = 1/*IFLA_XDP_FD*/;

	nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);

	memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));

	nla->nla_len = NLA_HDRLEN + nla_xdp->nla_len;



	req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);



	if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {

		printf("send to netlink: %s\n", strerror(errno));

		goto cleanup;

	}



	len = recv(sock, buf, sizeof(buf), 0);

	if (len < 0) {

		printf("recv from netlink: %s\n", strerror(errno));

		goto cleanup;

	}



	for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);

	     nh = NLMSG_NEXT(nh, len)) {

		if (nh->nlmsg_pid != getpid()) {

			printf("Wrong pid %d, expected %d\n",

			       nh->nlmsg_pid, getpid());

			goto cleanup;

		}

		if (nh->nlmsg_seq != seq) {

			printf("Wrong seq %d, expected %d\n",

			       nh->nlmsg_seq, seq);

			goto cleanup;

		}

		switch (nh->nlmsg_type) {

		case NLMSG_ERROR:

			err = (struct nlmsgerr *)NLMSG_DATA(nh);

			if (!err->error)

				continue;

			printf("nlmsg error %s\n", strerror(-err->error));

			goto cleanup;

		case NLMSG_DONE:

			break;

		}

	}



	ret = 0;



cleanup:

	close(sock);

	return ret;

}

samples/bpf/bpf_load.h

+1 −0
Original line number Diff line number Diff line
@@ -31,4 +31,5 @@ struct ksym { 


int load_kallsyms(void);

struct ksym *ksym_search(long key);

int set_link_xdp_fd(int ifindex, int fd);

#endif

samples/bpf/xdp1_user.c

+0 −93
Original line number Diff line number Diff line
@@ -5,111 +5,18 @@ 
 * License as published by the Free Software Foundation.

 */

#include <linux/bpf.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <assert.h>

#include <errno.h>

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/socket.h>

#include <unistd.h>



#include "bpf_load.h"

#include "bpf_util.h"

#include "libbpf.h"



static int set_link_xdp_fd(int ifindex, int fd)

{

	struct sockaddr_nl sa;

	int sock, seq = 0, len, ret = -1;

	char buf[4096];

	struct nlattr *nla, *nla_xdp;

	struct {

		struct nlmsghdr  nh;

		struct ifinfomsg ifinfo;

		char             attrbuf[64];

	} req;

	struct nlmsghdr *nh;

	struct nlmsgerr *err;



	memset(&sa, 0, sizeof(sa));

	sa.nl_family = AF_NETLINK;



	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);

	if (sock < 0) {

		printf("open netlink socket: %s\n", strerror(errno));

		return -1;

	}



	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {

		printf("bind to netlink: %s\n", strerror(errno));

		goto cleanup;

	}



	memset(&req, 0, sizeof(req));

	req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));

	req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;

	req.nh.nlmsg_type = RTM_SETLINK;

	req.nh.nlmsg_pid = 0;

	req.nh.nlmsg_seq = ++seq;

	req.ifinfo.ifi_family = AF_UNSPEC;

	req.ifinfo.ifi_index = ifindex;

	nla = (struct nlattr *)(((char *)&req)

				+ NLMSG_ALIGN(req.nh.nlmsg_len));

	nla->nla_type = NLA_F_NESTED | 43/*IFLA_XDP*/;



	nla_xdp = (struct nlattr *)((char *)nla + NLA_HDRLEN);

	nla_xdp->nla_type = 1/*IFLA_XDP_FD*/;

	nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);

	memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));

	nla->nla_len = NLA_HDRLEN + nla_xdp->nla_len;



	req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);



	if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {

		printf("send to netlink: %s\n", strerror(errno));

		goto cleanup;

	}



	len = recv(sock, buf, sizeof(buf), 0);

	if (len < 0) {

		printf("recv from netlink: %s\n", strerror(errno));

		goto cleanup;

	}



	for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);

	     nh = NLMSG_NEXT(nh, len)) {

		if (nh->nlmsg_pid != getpid()) {

			printf("Wrong pid %d, expected %d\n",

			       nh->nlmsg_pid, getpid());

			goto cleanup;

		}

		if (nh->nlmsg_seq != seq) {

			printf("Wrong seq %d, expected %d\n",

			       nh->nlmsg_seq, seq);

			goto cleanup;

		}

		switch (nh->nlmsg_type) {

		case NLMSG_ERROR:

			err = (struct nlmsgerr *)NLMSG_DATA(nh);

			if (!err->error)

				continue;

			printf("nlmsg error %s\n", strerror(-err->error));

			goto cleanup;

		case NLMSG_DONE:

			break;

		}

	}



	ret = 0;



cleanup:

	close(sock);

	return ret;

}



static int ifindex;



static void int_exit(int sig)

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