selftests/bpf: add tests for bpf_tcp_check_syncookie and bpf_skc_lookup_tcp

Add tests which verify that the new helpers work for both IPv4 and IPv6, by forcing SYN cookies to always on. Use a new network namespace to avoid clobbering the global SYN cookie settings. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-03-22 09:54:06 +08:00
parent 5792d52df1
commit bafc0ba826
6 changed files with 434 additions and 2 deletions
--- a/tools/testing/selftests/bpf/progs/test_tcp_check_syncookie_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tcp_check_syncookie_kern.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+// Copyright (c) 2019 Cloudflare
+
+#include <string.h>
+
+#include <linux/bpf.h>
+#include <linux/pkt_cls.h>
+#include <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <sys/socket.h>
+#include <linux/tcp.h>
+
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+struct bpf_map_def SEC("maps") results = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u64),
+	.max_entries = 1,
+};
+
+static __always_inline void check_syncookie(void *ctx, void *data,
+					    void *data_end)
+{
+	struct bpf_sock_tuple tup;
+	struct bpf_sock *sk;
+	struct ethhdr *ethh;
+	struct iphdr *ipv4h;
+	struct ipv6hdr *ipv6h;
+	struct tcphdr *tcph;
+	int ret;
+	__u32 key = 0;
+	__u64 value = 1;
+
+	ethh = data;
+	if (ethh + 1 > data_end)
+		return;
+
+	switch (bpf_ntohs(ethh->h_proto)) {
+	case ETH_P_IP:
+		ipv4h = data + sizeof(struct ethhdr);
+		if (ipv4h + 1 > data_end)
+			return;
+
+		if (ipv4h->ihl != 5)
+			return;
+
+		tcph = data + sizeof(struct ethhdr) + sizeof(struct iphdr);
+		if (tcph + 1 > data_end)
+			return;
+
+		tup.ipv4.saddr = ipv4h->saddr;
+		tup.ipv4.daddr = ipv4h->daddr;
+		tup.ipv4.sport = tcph->source;
+		tup.ipv4.dport = tcph->dest;
+
+		sk = bpf_skc_lookup_tcp(ctx, &tup, sizeof(tup.ipv4),
+					BPF_F_CURRENT_NETNS, 0);
+		if (!sk)
+			return;
+
+		if (sk->state != BPF_TCP_LISTEN)
+			goto release;
+
+		ret = bpf_tcp_check_syncookie(sk, ipv4h, sizeof(*ipv4h),
+					      tcph, sizeof(*tcph));
+		break;
+
+	case ETH_P_IPV6:
+		ipv6h = data + sizeof(struct ethhdr);
+		if (ipv6h + 1 > data_end)
+			return;
+
+		if (ipv6h->nexthdr != IPPROTO_TCP)
+			return;
+
+		tcph = data + sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
+		if (tcph + 1 > data_end)
+			return;
+
+		memcpy(tup.ipv6.saddr, &ipv6h->saddr, sizeof(tup.ipv6.saddr));
+		memcpy(tup.ipv6.daddr, &ipv6h->daddr, sizeof(tup.ipv6.daddr));
+		tup.ipv6.sport = tcph->source;
+		tup.ipv6.dport = tcph->dest;
+
+		sk = bpf_skc_lookup_tcp(ctx, &tup, sizeof(tup.ipv6),
+					BPF_F_CURRENT_NETNS, 0);
+		if (!sk)
+			return;
+
+		if (sk->state != BPF_TCP_LISTEN)
+			goto release;
+
+		ret = bpf_tcp_check_syncookie(sk, ipv6h, sizeof(*ipv6h),
+					      tcph, sizeof(*tcph));
+		break;
+
+	default:
+		return;
+	}
+
+	if (ret == 0)
+		bpf_map_update_elem(&results, &key, &value, 0);
+
+release:
+	bpf_sk_release(sk);
+}
+
+SEC("clsact/check_syncookie")
+int check_syncookie_clsact(struct __sk_buff *skb)
+{
+	check_syncookie(skb, (void *)(long)skb->data,
+			(void *)(long)skb->data_end);
+	return TC_ACT_OK;
+}
+
+SEC("xdp/check_syncookie")
+int check_syncookie_xdp(struct xdp_md *ctx)
+{
+	check_syncookie(ctx, (void *)(long)ctx->data,
+			(void *)(long)ctx->data_end);
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";