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authorDavid Ahern <dsahern@gmail.com>2018-05-09 20:34:27 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-05-11 00:10:57 +0200
commitfe616055f78457a0b78e0d3693d1ae26f2d7dab3 (patch)
tree2bab4dd9bff8b85508549c97886d92d82d7c22e1 /samples
parent87f5fc7e48dd3175b30dd03b41564e1a8e136323 (diff)
downloadlinux-fe616055f78457a0b78e0d3693d1ae26f2d7dab3.tar.bz2
samples/bpf: Add example of ipv4 and ipv6 forwarding in XDP
Simple example of fast-path forwarding. It has a serious flaw in not verifying the egress device index supports XDP forwarding. If the egress device does not packets are dropped. Take this only as a simple example of fast-path forwarding. Signed-off-by: David Ahern <dsahern@gmail.com> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'samples')
-rw-r--r--samples/bpf/Makefile4
-rw-r--r--samples/bpf/xdp_fwd_kern.c115
-rw-r--r--samples/bpf/xdp_fwd_user.c136
3 files changed, 255 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 8e0c7fb6d7cc..28513d6be1bf 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -46,6 +46,7 @@ hostprogs-y += syscall_tp
hostprogs-y += cpustat
hostprogs-y += xdp_adjust_tail
hostprogs-y += xdpsock
+hostprogs-y += xdp_fwd
# Libbpf dependencies
LIBBPF := ../../tools/lib/bpf/bpf.o ../../tools/lib/bpf/nlattr.o
@@ -100,6 +101,7 @@ syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o
cpustat-objs := bpf_load.o $(LIBBPF) cpustat_user.o
xdp_adjust_tail-objs := bpf_load.o $(LIBBPF) xdp_adjust_tail_user.o
xdpsock-objs := bpf_load.o $(LIBBPF) xdpsock_user.o
+xdp_fwd-objs := bpf_load.o $(LIBBPF) xdp_fwd_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@@ -154,6 +156,7 @@ always += syscall_tp_kern.o
always += cpustat_kern.o
always += xdp_adjust_tail_kern.o
always += xdpsock_kern.o
+always += xdp_fwd_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
HOSTCFLAGS += -I$(srctree)/tools/lib/
@@ -201,6 +204,7 @@ HOSTLOADLIBES_syscall_tp += -lelf
HOSTLOADLIBES_cpustat += -lelf
HOSTLOADLIBES_xdp_adjust_tail += -lelf
HOSTLOADLIBES_xdpsock += -lelf -pthread
+HOSTLOADLIBES_xdp_fwd += -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
diff --git a/samples/bpf/xdp_fwd_kern.c b/samples/bpf/xdp_fwd_kern.c
new file mode 100644
index 000000000000..cdf4fc383cc9
--- /dev/null
+++ b/samples/bpf/xdp_fwd_kern.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2017-18 David Ahern <dsahern@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#define KBUILD_MODNAME "foo"
+#include <uapi/linux/bpf.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+
+#include "bpf_helpers.h"
+
+#define IPV6_FLOWINFO_MASK cpu_to_be32(0x0FFFFFFF)
+
+struct bpf_map_def SEC("maps") tx_port = {
+ .type = BPF_MAP_TYPE_DEVMAP,
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ .max_entries = 64,
+};
+
+static __always_inline int xdp_fwd_flags(struct xdp_md *ctx, u32 flags)
+{
+ void *data_end = (void *)(long)ctx->data_end;
+ void *data = (void *)(long)ctx->data;
+ struct bpf_fib_lookup fib_params;
+ struct ethhdr *eth = data;
+ int out_index;
+ u16 h_proto;
+ u64 nh_off;
+
+ nh_off = sizeof(*eth);
+ if (data + nh_off > data_end)
+ return XDP_DROP;
+
+ __builtin_memset(&fib_params, 0, sizeof(fib_params));
+
+ h_proto = eth->h_proto;
+ if (h_proto == htons(ETH_P_IP)) {
+ struct iphdr *iph = data + nh_off;
+
+ if (iph + 1 > data_end)
+ return XDP_DROP;
+
+ fib_params.family = AF_INET;
+ fib_params.tos = iph->tos;
+ fib_params.l4_protocol = iph->protocol;
+ fib_params.sport = 0;
+ fib_params.dport = 0;
+ fib_params.tot_len = ntohs(iph->tot_len);
+ fib_params.ipv4_src = iph->saddr;
+ fib_params.ipv4_dst = iph->daddr;
+ } else if (h_proto == htons(ETH_P_IPV6)) {
+ struct in6_addr *src = (struct in6_addr *) fib_params.ipv6_src;
+ struct in6_addr *dst = (struct in6_addr *) fib_params.ipv6_dst;
+ struct ipv6hdr *iph = data + nh_off;
+
+ if (iph + 1 > data_end)
+ return XDP_DROP;
+
+ fib_params.family = AF_INET6;
+ fib_params.flowlabel = *(__be32 *)iph & IPV6_FLOWINFO_MASK;
+ fib_params.l4_protocol = iph->nexthdr;
+ fib_params.sport = 0;
+ fib_params.dport = 0;
+ fib_params.tot_len = ntohs(iph->payload_len);
+ *src = iph->saddr;
+ *dst = iph->daddr;
+ } else {
+ return XDP_PASS;
+ }
+
+ fib_params.ifindex = ctx->ingress_ifindex;
+
+ out_index = bpf_fib_lookup(ctx, &fib_params, sizeof(fib_params), flags);
+
+ /* verify egress index has xdp support
+ * TO-DO bpf_map_lookup_elem(&tx_port, &key) fails with
+ * cannot pass map_type 14 into func bpf_map_lookup_elem#1:
+ * NOTE: without verification that egress index supports XDP
+ * forwarding packets are dropped.
+ */
+ if (out_index > 0) {
+ memcpy(eth->h_dest, fib_params.dmac, ETH_ALEN);
+ memcpy(eth->h_source, fib_params.smac, ETH_ALEN);
+ return bpf_redirect_map(&tx_port, out_index, 0);
+ }
+
+ return XDP_PASS;
+}
+
+SEC("xdp_fwd")
+int xdp_fwd_prog(struct xdp_md *ctx)
+{
+ return xdp_fwd_flags(ctx, 0);
+}
+
+SEC("xdp_fwd_direct")
+int xdp_fwd_direct_prog(struct xdp_md *ctx)
+{
+ return xdp_fwd_flags(ctx, BPF_FIB_LOOKUP_DIRECT);
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/samples/bpf/xdp_fwd_user.c b/samples/bpf/xdp_fwd_user.c
new file mode 100644
index 000000000000..9c6606f57126
--- /dev/null
+++ b/samples/bpf/xdp_fwd_user.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2017-18 David Ahern <dsahern@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/bpf.h>
+#include <linux/if_link.h>
+#include <linux/limits.h>
+#include <net/if.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <libgen.h>
+
+#include "bpf_load.h"
+#include "bpf_util.h"
+#include "libbpf.h"
+
+
+static int do_attach(int idx, int fd, const char *name)
+{
+ int err;
+
+ err = bpf_set_link_xdp_fd(idx, fd, 0);
+ if (err < 0)
+ printf("ERROR: failed to attach program to %s\n", name);
+
+ return err;
+}
+
+static int do_detach(int idx, const char *name)
+{
+ int err;
+
+ err = bpf_set_link_xdp_fd(idx, -1, 0);
+ if (err < 0)
+ printf("ERROR: failed to detach program from %s\n", name);
+
+ return err;
+}
+
+static void usage(const char *prog)
+{
+ fprintf(stderr,
+ "usage: %s [OPTS] interface-list\n"
+ "\nOPTS:\n"
+ " -d detach program\n"
+ " -D direct table lookups (skip fib rules)\n",
+ prog);
+}
+
+int main(int argc, char **argv)
+{
+ char filename[PATH_MAX];
+ int opt, i, idx, err;
+ int prog_id = 0;
+ int attach = 1;
+ int ret = 0;
+
+ while ((opt = getopt(argc, argv, ":dD")) != -1) {
+ switch (opt) {
+ case 'd':
+ attach = 0;
+ break;
+ case 'D':
+ prog_id = 1;
+ break;
+ default:
+ usage(basename(argv[0]));
+ return 1;
+ }
+ }
+
+ if (optind == argc) {
+ usage(basename(argv[0]));
+ return 1;
+ }
+
+ if (attach) {
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+ if (access(filename, O_RDONLY) < 0) {
+ printf("error accessing file %s: %s\n",
+ filename, strerror(errno));
+ return 1;
+ }
+
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+
+ if (!prog_fd[prog_id]) {
+ printf("load_bpf_file: %s\n", strerror(errno));
+ return 1;
+ }
+ }
+ if (attach) {
+ for (i = 1; i < 64; ++i)
+ bpf_map_update_elem(map_fd[0], &i, &i, 0);
+ }
+
+ for (i = optind; i < argc; ++i) {
+ idx = if_nametoindex(argv[i]);
+ if (!idx)
+ idx = strtoul(argv[i], NULL, 0);
+
+ if (!idx) {
+ fprintf(stderr, "Invalid arg\n");
+ return 1;
+ }
+ if (!attach) {
+ err = do_detach(idx, argv[i]);
+ if (err)
+ ret = err;
+ } else {
+ err = do_attach(idx, prog_fd[prog_id], argv[i]);
+ if (err)
+ ret = err;
+ }
+ }
+
+ return ret;
+}