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authorNikita V. Shirokov <tehnerd@fb.com>2018-08-30 07:51:54 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-08-31 13:09:10 +0200
commit0f93c3995c93c41858e7459b8ad11053991038e0 (patch)
tree99891913a1f8a3dd024e86c6002fe703e8425ffd
parent9452048c79404e23f08678aec15fc04c7752923b (diff)
downloadmachiattobin-xdp-0f93c3995c93c41858e7459b8ad11053991038e0.tar.gz
bpf: add TCP_SAVE_SYN/TCP_SAVED_SYN sample program
Sample program which shows TCP_SAVE_SYN/TCP_SAVED_SYN usage example: bpf program which is doing TOS/TCLASS reflection (server would reply with a same TOS/TCLASS as client). Signed-off-by: Nikita V. Shirokov <tehnerd@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
-rw-r--r--samples/bpf/Makefile1
-rw-r--r--samples/bpf/tcp_tos_reflect_kern.c87
2 files changed, 88 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 36f9f41d094b..be0a961450bc 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -153,6 +153,7 @@ always += tcp_cong_kern.o
always += tcp_iw_kern.o
always += tcp_clamp_kern.o
always += tcp_basertt_kern.o
+always += tcp_tos_reflect_kern.o
always += xdp_redirect_kern.o
always += xdp_redirect_map_kern.o
always += xdp_redirect_cpu_kern.o
diff --git a/samples/bpf/tcp_tos_reflect_kern.c b/samples/bpf/tcp_tos_reflect_kern.c
new file mode 100644
index 000000000000..d51dab19eca6
--- /dev/null
+++ b/samples/bpf/tcp_tos_reflect_kern.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Facebook
+ *
+ * BPF program to automatically reflect TOS option from received syn packet
+ *
+ * Use load_sock_ops to load this BPF program.
+ */
+
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/tcp.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/if_packet.h>
+#include <uapi/linux/ip.h>
+#include <uapi/linux/ipv6.h>
+#include <uapi/linux/in.h>
+#include <linux/socket.h>
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+#define DEBUG 1
+
+#define bpf_printk(fmt, ...) \
+({ \
+ char ____fmt[] = fmt; \
+ bpf_trace_printk(____fmt, sizeof(____fmt), \
+ ##__VA_ARGS__); \
+})
+
+SEC("sockops")
+int bpf_basertt(struct bpf_sock_ops *skops)
+{
+ char header[sizeof(struct ipv6hdr)];
+ struct ipv6hdr *hdr6;
+ struct iphdr *hdr;
+ int hdr_size = 0;
+ int save_syn = 1;
+ int tos = 0;
+ int rv = 0;
+ int op;
+
+ op = (int) skops->op;
+
+#ifdef DEBUG
+ bpf_printk("BPF command: %d\n", op);
+#endif
+ switch (op) {
+ case BPF_SOCK_OPS_TCP_LISTEN_CB:
+ rv = bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN,
+ &save_syn, sizeof(save_syn));
+ break;
+ case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
+ if (skops->family == AF_INET)
+ hdr_size = sizeof(struct iphdr);
+ else
+ hdr_size = sizeof(struct ipv6hdr);
+ rv = bpf_getsockopt(skops, SOL_TCP, TCP_SAVED_SYN,
+ header, hdr_size);
+ if (!rv) {
+ if (skops->family == AF_INET) {
+ hdr = (struct iphdr *) header;
+ tos = hdr->tos;
+ if (tos != 0)
+ bpf_setsockopt(skops, SOL_IP, IP_TOS,
+ &tos, sizeof(tos));
+ } else {
+ hdr6 = (struct ipv6hdr *) header;
+ tos = ((hdr6->priority) << 4 |
+ (hdr6->flow_lbl[0]) >> 4);
+ if (tos)
+ bpf_setsockopt(skops, SOL_IPV6,
+ IPV6_TCLASS,
+ &tos, sizeof(tos));
+ }
+ rv = 0;
+ }
+ break;
+ default:
+ rv = -1;
+ }
+#ifdef DEBUG
+ bpf_printk("Returning %d\n", rv);
+#endif
+ skops->reply = rv;
+ return 1;
+}
+char _license[] SEC("license") = "GPL";