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Date: Thu, 7 Jul 2022 13:47:34 +0300
From: Yauheni Kaliuta <ykaliuta@...hat.com>
To: Maxim Mikityanskiy <maximmi@...dia.com>
Cc: bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>, netdev@...r.kernel.org,
Tariq Toukan <tariqt@...dia.com>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
David Ahern <dsahern@...nel.org>,
Shuah Khan <shuah@...nel.org>,
Jesper Dangaard Brouer <hawk@...nel.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Joe Stringer <joe@...ium.io>,
Florent Revest <revest@...omium.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@...r.kernel.org>,
Toke Høiland-Jørgensen <toke@...e.dk>,
Kumar Kartikeya Dwivedi <memxor@...il.com>,
Florian Westphal <fw@...len.de>,
Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH bpf-next v10 4/6] selftests/bpf: Add selftests for raw
syncookie helpers
Hi, Maxim!
The test is not buildable for me with CONFIG_NF_CONNTRACK=m due to
missing BPF_F_CURRENT_NETNS in vmlinux.h.
On Wed, Jun 15, 2022 at 4:49 PM Maxim Mikityanskiy <maximmi@...dia.com> wrote:
>
> This commit adds selftests for the new BPF helpers:
> bpf_tcp_raw_{gen,check}_syncookie_ipv{4,6}.
>
> xdp_synproxy_kern.c is a BPF program that generates SYN cookies on
> allowed TCP ports and sends SYNACKs to clients, accelerating synproxy
> iptables module.
>
> xdp_synproxy.c is a userspace control application that allows to
> configure the following options in runtime: list of allowed ports, MSS,
> window scale, TTL.
>
> A selftest is added to prog_tests that leverages the above programs to
> test the functionality of the new helpers.
>
> Signed-off-by: Maxim Mikityanskiy <maximmi@...dia.com>
> Reviewed-by: Tariq Toukan <tariqt@...dia.com>
> ---
> tools/testing/selftests/bpf/.gitignore | 1 +
> tools/testing/selftests/bpf/Makefile | 3 +-
> .../selftests/bpf/prog_tests/xdp_synproxy.c | 146 ++++
> .../selftests/bpf/progs/xdp_synproxy_kern.c | 763 ++++++++++++++++++
> tools/testing/selftests/bpf/xdp_synproxy.c | 418 ++++++++++
> 5 files changed, 1330 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_synproxy.c
> create mode 100644 tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
> create mode 100644 tools/testing/selftests/bpf/xdp_synproxy.c
>
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index 595565eb68c0..ca2f47f45670 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -43,3 +43,4 @@ test_cpp
> *.tmp
> xdpxceiver
> xdp_redirect_multi
> +xdp_synproxy
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 8ad7a733a505..e4ce21f4a474 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -82,7 +82,7 @@ TEST_PROGS_EXTENDED := with_addr.sh \
> TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
> flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \
> test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \
> - xdpxceiver xdp_redirect_multi
> + xdpxceiver xdp_redirect_multi xdp_synproxy
>
> TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
>
> @@ -502,6 +502,7 @@ TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \
> cap_helpers.c
> TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \
> $(OUTPUT)/liburandom_read.so \
> + $(OUTPUT)/xdp_synproxy \
> ima_setup.sh \
> $(wildcard progs/btf_dump_test_case_*.c)
> TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_synproxy.c b/tools/testing/selftests/bpf/prog_tests/xdp_synproxy.c
> new file mode 100644
> index 000000000000..d9ee884c2a2b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_synproxy.c
> @@ -0,0 +1,146 @@
> +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
> +/* Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
> +
> +#include <test_progs.h>
> +#include <network_helpers.h>
> +#include <ctype.h>
> +
> +#define CMD_OUT_BUF_SIZE 1023
> +
> +#define SYS(cmd) ({ \
> + if (!ASSERT_OK(system(cmd), (cmd))) \
> + goto out; \
> +})
> +
> +#define SYS_OUT(cmd) ({ \
> + FILE *f = popen((cmd), "r"); \
> + if (!ASSERT_OK_PTR(f, (cmd))) \
> + goto out; \
> + f; \
> +})
> +
> +/* out must be at least `size * 4 + 1` bytes long */
> +static void escape_str(char *out, const char *in, size_t size)
> +{
> + static const char *hex = "0123456789ABCDEF";
> + size_t i;
> +
> + for (i = 0; i < size; i++) {
> + if (isprint(in[i]) && in[i] != '\\' && in[i] != '\'') {
> + *out++ = in[i];
> + } else {
> + *out++ = '\\';
> + *out++ = 'x';
> + *out++ = hex[(in[i] >> 4) & 0xf];
> + *out++ = hex[in[i] & 0xf];
> + }
> + }
> + *out++ = '\0';
> +}
> +
> +static bool expect_str(char *buf, size_t size, const char *str, const char *name)
> +{
> + static char escbuf_expected[CMD_OUT_BUF_SIZE * 4];
> + static char escbuf_actual[CMD_OUT_BUF_SIZE * 4];
> + static int duration = 0;
> + bool ok;
> +
> + ok = size == strlen(str) && !memcmp(buf, str, size);
> +
> + if (!ok) {
> + escape_str(escbuf_expected, str, strlen(str));
> + escape_str(escbuf_actual, buf, size);
> + }
> + CHECK(!ok, name, "unexpected %s: actual '%s' != expected '%s'\n",
> + name, escbuf_actual, escbuf_expected);
> +
> + return ok;
> +}
> +
> +void test_xdp_synproxy(void)
> +{
> + int server_fd = -1, client_fd = -1, accept_fd = -1;
> + struct nstoken *ns = NULL;
> + FILE *ctrl_file = NULL;
> + char buf[CMD_OUT_BUF_SIZE];
> + size_t size;
> +
> + SYS("ip netns add synproxy");
> +
> + SYS("ip link add tmp0 type veth peer name tmp1");
> + SYS("ip link set tmp1 netns synproxy");
> + SYS("ip link set tmp0 up");
> + SYS("ip addr replace 198.18.0.1/24 dev tmp0");
> +
> + /* When checksum offload is enabled, the XDP program sees wrong
> + * checksums and drops packets.
> + */
> + SYS("ethtool -K tmp0 tx off");
> + /* Workaround required for veth. */
> + SYS("ip link set tmp0 xdp object xdp_dummy.o section xdp 2> /dev/null");
> +
> + ns = open_netns("synproxy");
> + if (!ASSERT_OK_PTR(ns, "setns"))
> + goto out;
> +
> + SYS("ip link set lo up");
> + SYS("ip link set tmp1 up");
> + SYS("ip addr replace 198.18.0.2/24 dev tmp1");
> + SYS("sysctl -w net.ipv4.tcp_syncookies=2");
> + SYS("sysctl -w net.ipv4.tcp_timestamps=1");
> + SYS("sysctl -w net.netfilter.nf_conntrack_tcp_loose=0");
> + SYS("iptables -t raw -I PREROUTING \
> + -i tmp1 -p tcp -m tcp --syn --dport 8080 -j CT --notrack");
> + SYS("iptables -t filter -A INPUT \
> + -i tmp1 -p tcp -m tcp --dport 8080 -m state --state INVALID,UNTRACKED \
> + -j SYNPROXY --sack-perm --timestamp --wscale 7 --mss 1460");
> + SYS("iptables -t filter -A INPUT \
> + -i tmp1 -m state --state INVALID -j DROP");
> +
> + ctrl_file = SYS_OUT("./xdp_synproxy --iface tmp1 --ports 8080 --single \
> + --mss4 1460 --mss6 1440 --wscale 7 --ttl 64");
> + size = fread(buf, 1, sizeof(buf), ctrl_file);
> + pclose(ctrl_file);
> + if (!expect_str(buf, size, "Total SYNACKs generated: 0\n",
> + "initial SYNACKs"))
> + goto out;
> +
> + server_fd = start_server(AF_INET, SOCK_STREAM, "198.18.0.2", 8080, 0);
> + if (!ASSERT_GE(server_fd, 0, "start_server"))
> + goto out;
> +
> + close_netns(ns);
> + ns = NULL;
> +
> + client_fd = connect_to_fd(server_fd, 10000);
> + if (!ASSERT_GE(client_fd, 0, "connect_to_fd"))
> + goto out;
> +
> + accept_fd = accept(server_fd, NULL, NULL);
> + if (!ASSERT_GE(accept_fd, 0, "accept"))
> + goto out;
> +
> + ns = open_netns("synproxy");
> + if (!ASSERT_OK_PTR(ns, "setns"))
> + goto out;
> +
> + ctrl_file = SYS_OUT("./xdp_synproxy --iface tmp1 --single");
> + size = fread(buf, 1, sizeof(buf), ctrl_file);
> + pclose(ctrl_file);
> + if (!expect_str(buf, size, "Total SYNACKs generated: 1\n",
> + "SYNACKs after connection"))
> + goto out;
> +
> +out:
> + if (accept_fd >= 0)
> + close(accept_fd);
> + if (client_fd >= 0)
> + close(client_fd);
> + if (server_fd >= 0)
> + close(server_fd);
> + if (ns)
> + close_netns(ns);
> +
> + system("ip link del tmp0");
> + system("ip netns del synproxy");
> +}
> diff --git a/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
> new file mode 100644
> index 000000000000..53b9865276a4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
> @@ -0,0 +1,763 @@
> +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
> +/* Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
> +
> +#include "vmlinux.h"
> +
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_endian.h>
> +#include <asm/errno.h>
> +
> +#define NSEC_PER_SEC 1000000000L
> +
> +#define ETH_ALEN 6
> +#define ETH_P_IP 0x0800
> +#define ETH_P_IPV6 0x86DD
> +
> +#define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3])
> +
> +#define IP_DF 0x4000
> +#define IP_MF 0x2000
> +#define IP_OFFSET 0x1fff
> +
> +#define NEXTHDR_TCP 6
> +
> +#define TCPOPT_NOP 1
> +#define TCPOPT_EOL 0
> +#define TCPOPT_MSS 2
> +#define TCPOPT_WINDOW 3
> +#define TCPOPT_SACK_PERM 4
> +#define TCPOPT_TIMESTAMP 8
> +
> +#define TCPOLEN_MSS 4
> +#define TCPOLEN_WINDOW 3
> +#define TCPOLEN_SACK_PERM 2
> +#define TCPOLEN_TIMESTAMP 10
> +
> +#define TCP_TS_HZ 1000
> +#define TS_OPT_WSCALE_MASK 0xf
> +#define TS_OPT_SACK (1 << 4)
> +#define TS_OPT_ECN (1 << 5)
> +#define TSBITS 6
> +#define TSMASK (((__u32)1 << TSBITS) - 1)
> +#define TCP_MAX_WSCALE 14U
> +
> +#define IPV4_MAXLEN 60
> +#define TCP_MAXLEN 60
> +
> +#define DEFAULT_MSS4 1460
> +#define DEFAULT_MSS6 1440
> +#define DEFAULT_WSCALE 7
> +#define DEFAULT_TTL 64
> +#define MAX_ALLOWED_PORTS 8
> +
> +#define swap(a, b) \
> + do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
> +
> +#define __get_unaligned_t(type, ptr) ({ \
> + const struct { type x; } __attribute__((__packed__)) *__pptr = (typeof(__pptr))(ptr); \
> + __pptr->x; \
> +})
> +
> +#define get_unaligned(ptr) __get_unaligned_t(typeof(*(ptr)), (ptr))
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __type(key, __u32);
> + __type(value, __u64);
> + __uint(max_entries, 2);
> +} values SEC(".maps");
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __type(key, __u32);
> + __type(value, __u16);
> + __uint(max_entries, MAX_ALLOWED_PORTS);
> +} allowed_ports SEC(".maps");
> +
> +extern struct nf_conn *bpf_xdp_ct_lookup(struct xdp_md *xdp_ctx,
> + struct bpf_sock_tuple *bpf_tuple,
> + __u32 len_tuple,
> + struct bpf_ct_opts *opts,
> + __u32 len_opts) __ksym;
> +
> +extern void bpf_ct_release(struct nf_conn *ct) __ksym;
> +
> +static __always_inline void swap_eth_addr(__u8 *a, __u8 *b)
> +{
> + __u8 tmp[ETH_ALEN];
> +
> + __builtin_memcpy(tmp, a, ETH_ALEN);
> + __builtin_memcpy(a, b, ETH_ALEN);
> + __builtin_memcpy(b, tmp, ETH_ALEN);
> +}
> +
> +static __always_inline __u16 csum_fold(__u32 csum)
> +{
> + csum = (csum & 0xffff) + (csum >> 16);
> + csum = (csum & 0xffff) + (csum >> 16);
> + return (__u16)~csum;
> +}
> +
> +static __always_inline __u16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
> + __u32 len, __u8 proto,
> + __u32 csum)
> +{
> + __u64 s = csum;
> +
> + s += (__u32)saddr;
> + s += (__u32)daddr;
> +#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
> + s += proto + len;
> +#elif __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
> + s += (proto + len) << 8;
> +#else
> +#error Unknown endian
> +#endif
> + s = (s & 0xffffffff) + (s >> 32);
> + s = (s & 0xffffffff) + (s >> 32);
> +
> + return csum_fold((__u32)s);
> +}
> +
> +static __always_inline __u16 csum_ipv6_magic(const struct in6_addr *saddr,
> + const struct in6_addr *daddr,
> + __u32 len, __u8 proto, __u32 csum)
> +{
> + __u64 sum = csum;
> + int i;
> +
> +#pragma unroll
> + for (i = 0; i < 4; i++)
> + sum += (__u32)saddr->in6_u.u6_addr32[i];
> +
> +#pragma unroll
> + for (i = 0; i < 4; i++)
> + sum += (__u32)daddr->in6_u.u6_addr32[i];
> +
> + /* Don't combine additions to avoid 32-bit overflow. */
> + sum += bpf_htonl(len);
> + sum += bpf_htonl(proto);
> +
> + sum = (sum & 0xffffffff) + (sum >> 32);
> + sum = (sum & 0xffffffff) + (sum >> 32);
> +
> + return csum_fold((__u32)sum);
> +}
> +
> +static __always_inline __u64 tcp_clock_ns(void)
> +{
> + return bpf_ktime_get_ns();
> +}
> +
> +static __always_inline __u32 tcp_ns_to_ts(__u64 ns)
> +{
> + return ns / (NSEC_PER_SEC / TCP_TS_HZ);
> +}
> +
> +static __always_inline __u32 tcp_time_stamp_raw(void)
> +{
> + return tcp_ns_to_ts(tcp_clock_ns());
> +}
> +
> +struct tcpopt_context {
> + __u8 *ptr;
> + __u8 *end;
> + void *data_end;
> + __be32 *tsecr;
> + __u8 wscale;
> + bool option_timestamp;
> + bool option_sack;
> +};
> +
> +static int tscookie_tcpopt_parse(struct tcpopt_context *ctx)
> +{
> + __u8 opcode, opsize;
> +
> + if (ctx->ptr >= ctx->end)
> + return 1;
> + if (ctx->ptr >= ctx->data_end)
> + return 1;
> +
> + opcode = ctx->ptr[0];
> +
> + if (opcode == TCPOPT_EOL)
> + return 1;
> + if (opcode == TCPOPT_NOP) {
> + ++ctx->ptr;
> + return 0;
> + }
> +
> + if (ctx->ptr + 1 >= ctx->end)
> + return 1;
> + if (ctx->ptr + 1 >= ctx->data_end)
> + return 1;
> + opsize = ctx->ptr[1];
> + if (opsize < 2)
> + return 1;
> +
> + if (ctx->ptr + opsize > ctx->end)
> + return 1;
> +
> + switch (opcode) {
> + case TCPOPT_WINDOW:
> + if (opsize == TCPOLEN_WINDOW && ctx->ptr + TCPOLEN_WINDOW <= ctx->data_end)
> + ctx->wscale = ctx->ptr[2] < TCP_MAX_WSCALE ? ctx->ptr[2] : TCP_MAX_WSCALE;
> + break;
> + case TCPOPT_TIMESTAMP:
> + if (opsize == TCPOLEN_TIMESTAMP && ctx->ptr + TCPOLEN_TIMESTAMP <= ctx->data_end) {
> + ctx->option_timestamp = true;
> + /* Client's tsval becomes our tsecr. */
> + *ctx->tsecr = get_unaligned((__be32 *)(ctx->ptr + 2));
> + }
> + break;
> + case TCPOPT_SACK_PERM:
> + if (opsize == TCPOLEN_SACK_PERM)
> + ctx->option_sack = true;
> + break;
> + }
> +
> + ctx->ptr += opsize;
> +
> + return 0;
> +}
> +
> +static int tscookie_tcpopt_parse_batch(__u32 index, void *context)
> +{
> + int i;
> +
> + for (i = 0; i < 7; i++)
> + if (tscookie_tcpopt_parse(context))
> + return 1;
> + return 0;
> +}
> +
> +static __always_inline bool tscookie_init(struct tcphdr *tcp_header,
> + __u16 tcp_len, __be32 *tsval,
> + __be32 *tsecr, void *data_end)
> +{
> + struct tcpopt_context loop_ctx = {
> + .ptr = (__u8 *)(tcp_header + 1),
> + .end = (__u8 *)tcp_header + tcp_len,
> + .data_end = data_end,
> + .tsecr = tsecr,
> + .wscale = TS_OPT_WSCALE_MASK,
> + .option_timestamp = false,
> + .option_sack = false,
> + };
> + u32 cookie;
> +
> + bpf_loop(6, tscookie_tcpopt_parse_batch, &loop_ctx, 0);
> +
> + if (!loop_ctx.option_timestamp)
> + return false;
> +
> + cookie = tcp_time_stamp_raw() & ~TSMASK;
> + cookie |= loop_ctx.wscale & TS_OPT_WSCALE_MASK;
> + if (loop_ctx.option_sack)
> + cookie |= TS_OPT_SACK;
> + if (tcp_header->ece && tcp_header->cwr)
> + cookie |= TS_OPT_ECN;
> + *tsval = bpf_htonl(cookie);
> +
> + return true;
> +}
> +
> +static __always_inline void values_get_tcpipopts(__u16 *mss, __u8 *wscale,
> + __u8 *ttl, bool ipv6)
> +{
> + __u32 key = 0;
> + __u64 *value;
> +
> + value = bpf_map_lookup_elem(&values, &key);
> + if (value && *value != 0) {
> + if (ipv6)
> + *mss = (*value >> 32) & 0xffff;
> + else
> + *mss = *value & 0xffff;
> + *wscale = (*value >> 16) & 0xf;
> + *ttl = (*value >> 24) & 0xff;
> + return;
> + }
> +
> + *mss = ipv6 ? DEFAULT_MSS6 : DEFAULT_MSS4;
> + *wscale = DEFAULT_WSCALE;
> + *ttl = DEFAULT_TTL;
> +}
> +
> +static __always_inline void values_inc_synacks(void)
> +{
> + __u32 key = 1;
> + __u32 *value;
> +
> + value = bpf_map_lookup_elem(&values, &key);
> + if (value)
> + __sync_fetch_and_add(value, 1);
> +}
> +
> +static __always_inline bool check_port_allowed(__u16 port)
> +{
> + __u32 i;
> +
> + for (i = 0; i < MAX_ALLOWED_PORTS; i++) {
> + __u32 key = i;
> + __u16 *value;
> +
> + value = bpf_map_lookup_elem(&allowed_ports, &key);
> +
> + if (!value)
> + break;
> + /* 0 is a terminator value. Check it first to avoid matching on
> + * a forbidden port == 0 and returning true.
> + */
> + if (*value == 0)
> + break;
> +
> + if (*value == port)
> + return true;
> + }
> +
> + return false;
> +}
> +
> +struct header_pointers {
> + struct ethhdr *eth;
> + struct iphdr *ipv4;
> + struct ipv6hdr *ipv6;
> + struct tcphdr *tcp;
> + __u16 tcp_len;
> +};
> +
> +static __always_inline int tcp_dissect(void *data, void *data_end,
> + struct header_pointers *hdr)
> +{
> + hdr->eth = data;
> + if (hdr->eth + 1 > data_end)
> + return XDP_DROP;
> +
> + switch (bpf_ntohs(hdr->eth->h_proto)) {
> + case ETH_P_IP:
> + hdr->ipv6 = NULL;
> +
> + hdr->ipv4 = (void *)hdr->eth + sizeof(*hdr->eth);
> + if (hdr->ipv4 + 1 > data_end)
> + return XDP_DROP;
> + if (hdr->ipv4->ihl * 4 < sizeof(*hdr->ipv4))
> + return XDP_DROP;
> + if (hdr->ipv4->version != 4)
> + return XDP_DROP;
> +
> + if (hdr->ipv4->protocol != IPPROTO_TCP)
> + return XDP_PASS;
> +
> + hdr->tcp = (void *)hdr->ipv4 + hdr->ipv4->ihl * 4;
> + break;
> + case ETH_P_IPV6:
> + hdr->ipv4 = NULL;
> +
> + hdr->ipv6 = (void *)hdr->eth + sizeof(*hdr->eth);
> + if (hdr->ipv6 + 1 > data_end)
> + return XDP_DROP;
> + if (hdr->ipv6->version != 6)
> + return XDP_DROP;
> +
> + /* XXX: Extension headers are not supported and could circumvent
> + * XDP SYN flood protection.
> + */
> + if (hdr->ipv6->nexthdr != NEXTHDR_TCP)
> + return XDP_PASS;
> +
> + hdr->tcp = (void *)hdr->ipv6 + sizeof(*hdr->ipv6);
> + break;
> + default:
> + /* XXX: VLANs will circumvent XDP SYN flood protection. */
> + return XDP_PASS;
> + }
> +
> + if (hdr->tcp + 1 > data_end)
> + return XDP_DROP;
> + hdr->tcp_len = hdr->tcp->doff * 4;
> + if (hdr->tcp_len < sizeof(*hdr->tcp))
> + return XDP_DROP;
> +
> + return XDP_TX;
> +}
> +
> +static __always_inline int tcp_lookup(struct xdp_md *ctx, struct header_pointers *hdr)
> +{
> + struct bpf_ct_opts ct_lookup_opts = {
> + .netns_id = BPF_F_CURRENT_NETNS,
> + .l4proto = IPPROTO_TCP,
> + };
> + struct bpf_sock_tuple tup = {};
> + struct nf_conn *ct;
> + __u32 tup_size;
> +
> + if (hdr->ipv4) {
> + /* TCP doesn't normally use fragments, and XDP can't reassemble
> + * them.
> + */
> + if ((hdr->ipv4->frag_off & bpf_htons(IP_DF | IP_MF | IP_OFFSET)) != bpf_htons(IP_DF))
> + return XDP_DROP;
> +
> + tup.ipv4.saddr = hdr->ipv4->saddr;
> + tup.ipv4.daddr = hdr->ipv4->daddr;
> + tup.ipv4.sport = hdr->tcp->source;
> + tup.ipv4.dport = hdr->tcp->dest;
> + tup_size = sizeof(tup.ipv4);
> + } else if (hdr->ipv6) {
> + __builtin_memcpy(tup.ipv6.saddr, &hdr->ipv6->saddr, sizeof(tup.ipv6.saddr));
> + __builtin_memcpy(tup.ipv6.daddr, &hdr->ipv6->daddr, sizeof(tup.ipv6.daddr));
> + tup.ipv6.sport = hdr->tcp->source;
> + tup.ipv6.dport = hdr->tcp->dest;
> + tup_size = sizeof(tup.ipv6);
> + } else {
> + /* The verifier can't track that either ipv4 or ipv6 is not
> + * NULL.
> + */
> + return XDP_ABORTED;
> + }
> + ct = bpf_xdp_ct_lookup(ctx, &tup, tup_size, &ct_lookup_opts, sizeof(ct_lookup_opts));
> + if (ct) {
> + unsigned long status = ct->status;
> +
> + bpf_ct_release(ct);
> + if (status & IPS_CONFIRMED_BIT)
> + return XDP_PASS;
> + } else if (ct_lookup_opts.error != -ENOENT) {
> + return XDP_ABORTED;
> + }
> +
> + /* error == -ENOENT || !(status & IPS_CONFIRMED_BIT) */
> + return XDP_TX;
> +}
> +
> +static __always_inline __u8 tcp_mkoptions(__be32 *buf, __be32 *tsopt, __u16 mss,
> + __u8 wscale)
> +{
> + __be32 *start = buf;
> +
> + *buf++ = bpf_htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss);
> +
> + if (!tsopt)
> + return buf - start;
> +
> + if (tsopt[0] & bpf_htonl(1 << 4))
> + *buf++ = bpf_htonl((TCPOPT_SACK_PERM << 24) |
> + (TCPOLEN_SACK_PERM << 16) |
> + (TCPOPT_TIMESTAMP << 8) |
> + TCPOLEN_TIMESTAMP);
> + else
> + *buf++ = bpf_htonl((TCPOPT_NOP << 24) |
> + (TCPOPT_NOP << 16) |
> + (TCPOPT_TIMESTAMP << 8) |
> + TCPOLEN_TIMESTAMP);
> + *buf++ = tsopt[0];
> + *buf++ = tsopt[1];
> +
> + if ((tsopt[0] & bpf_htonl(0xf)) != bpf_htonl(0xf))
> + *buf++ = bpf_htonl((TCPOPT_NOP << 24) |
> + (TCPOPT_WINDOW << 16) |
> + (TCPOLEN_WINDOW << 8) |
> + wscale);
> +
> + return buf - start;
> +}
> +
> +static __always_inline void tcp_gen_synack(struct tcphdr *tcp_header,
> + __u32 cookie, __be32 *tsopt,
> + __u16 mss, __u8 wscale)
> +{
> + void *tcp_options;
> +
> + tcp_flag_word(tcp_header) = TCP_FLAG_SYN | TCP_FLAG_ACK;
> + if (tsopt && (tsopt[0] & bpf_htonl(1 << 5)))
> + tcp_flag_word(tcp_header) |= TCP_FLAG_ECE;
> + tcp_header->doff = 5; /* doff is part of tcp_flag_word. */
> + swap(tcp_header->source, tcp_header->dest);
> + tcp_header->ack_seq = bpf_htonl(bpf_ntohl(tcp_header->seq) + 1);
> + tcp_header->seq = bpf_htonl(cookie);
> + tcp_header->window = 0;
> + tcp_header->urg_ptr = 0;
> + tcp_header->check = 0; /* Calculate checksum later. */
> +
> + tcp_options = (void *)(tcp_header + 1);
> + tcp_header->doff += tcp_mkoptions(tcp_options, tsopt, mss, wscale);
> +}
> +
> +static __always_inline void tcpv4_gen_synack(struct header_pointers *hdr,
> + __u32 cookie, __be32 *tsopt)
> +{
> + __u8 wscale;
> + __u16 mss;
> + __u8 ttl;
> +
> + values_get_tcpipopts(&mss, &wscale, &ttl, false);
> +
> + swap_eth_addr(hdr->eth->h_source, hdr->eth->h_dest);
> +
> + swap(hdr->ipv4->saddr, hdr->ipv4->daddr);
> + hdr->ipv4->check = 0; /* Calculate checksum later. */
> + hdr->ipv4->tos = 0;
> + hdr->ipv4->id = 0;
> + hdr->ipv4->ttl = ttl;
> +
> + tcp_gen_synack(hdr->tcp, cookie, tsopt, mss, wscale);
> +
> + hdr->tcp_len = hdr->tcp->doff * 4;
> + hdr->ipv4->tot_len = bpf_htons(sizeof(*hdr->ipv4) + hdr->tcp_len);
> +}
> +
> +static __always_inline void tcpv6_gen_synack(struct header_pointers *hdr,
> + __u32 cookie, __be32 *tsopt)
> +{
> + __u8 wscale;
> + __u16 mss;
> + __u8 ttl;
> +
> + values_get_tcpipopts(&mss, &wscale, &ttl, true);
> +
> + swap_eth_addr(hdr->eth->h_source, hdr->eth->h_dest);
> +
> + swap(hdr->ipv6->saddr, hdr->ipv6->daddr);
> + *(__be32 *)hdr->ipv6 = bpf_htonl(0x60000000);
> + hdr->ipv6->hop_limit = ttl;
> +
> + tcp_gen_synack(hdr->tcp, cookie, tsopt, mss, wscale);
> +
> + hdr->tcp_len = hdr->tcp->doff * 4;
> + hdr->ipv6->payload_len = bpf_htons(hdr->tcp_len);
> +}
> +
> +static __always_inline int syncookie_handle_syn(struct header_pointers *hdr,
> + struct xdp_md *ctx,
> + void *data, void *data_end)
> +{
> + __u32 old_pkt_size, new_pkt_size;
> + /* Unlike clang 10, clang 11 and 12 generate code that doesn't pass the
> + * BPF verifier if tsopt is not volatile. Volatile forces it to store
> + * the pointer value and use it directly, otherwise tcp_mkoptions is
> + * (mis)compiled like this:
> + * if (!tsopt)
> + * return buf - start;
> + * reg = stored_return_value_of_tscookie_init;
> + * if (reg)
> + * tsopt = tsopt_buf;
> + * else
> + * tsopt = NULL;
> + * ...
> + * *buf++ = tsopt[1];
> + * It creates a dead branch where tsopt is assigned NULL, but the
> + * verifier can't prove it's dead and blocks the program.
> + */
> + __be32 * volatile tsopt = NULL;
> + __be32 tsopt_buf[2] = {};
> + __u16 ip_len;
> + __u32 cookie;
> + __s64 value;
> +
> + /* Checksum is not yet verified, but both checksum failure and TCP
> + * header checks return XDP_DROP, so the order doesn't matter.
> + */
> + if (hdr->tcp->fin || hdr->tcp->rst)
> + return XDP_DROP;
> +
> + /* Issue SYN cookies on allowed ports, drop SYN packets on blocked
> + * ports.
> + */
> + if (!check_port_allowed(bpf_ntohs(hdr->tcp->dest)))
> + return XDP_DROP;
> +
> + if (hdr->ipv4) {
> + /* Check the IPv4 and TCP checksums before creating a SYNACK. */
> + value = bpf_csum_diff(0, 0, (void *)hdr->ipv4, hdr->ipv4->ihl * 4, 0);
> + if (value < 0)
> + return XDP_ABORTED;
> + if (csum_fold(value) != 0)
> + return XDP_DROP; /* Bad IPv4 checksum. */
> +
> + value = bpf_csum_diff(0, 0, (void *)hdr->tcp, hdr->tcp_len, 0);
> + if (value < 0)
> + return XDP_ABORTED;
> + if (csum_tcpudp_magic(hdr->ipv4->saddr, hdr->ipv4->daddr,
> + hdr->tcp_len, IPPROTO_TCP, value) != 0)
> + return XDP_DROP; /* Bad TCP checksum. */
> +
> + ip_len = sizeof(*hdr->ipv4);
> +
> + value = bpf_tcp_raw_gen_syncookie_ipv4(hdr->ipv4, hdr->tcp,
> + hdr->tcp_len);
> + } else if (hdr->ipv6) {
> + /* Check the TCP checksum before creating a SYNACK. */
> + value = bpf_csum_diff(0, 0, (void *)hdr->tcp, hdr->tcp_len, 0);
> + if (value < 0)
> + return XDP_ABORTED;
> + if (csum_ipv6_magic(&hdr->ipv6->saddr, &hdr->ipv6->daddr,
> + hdr->tcp_len, IPPROTO_TCP, value) != 0)
> + return XDP_DROP; /* Bad TCP checksum. */
> +
> + ip_len = sizeof(*hdr->ipv6);
> +
> + value = bpf_tcp_raw_gen_syncookie_ipv6(hdr->ipv6, hdr->tcp,
> + hdr->tcp_len);
> + } else {
> + return XDP_ABORTED;
> + }
> +
> + if (value < 0)
> + return XDP_ABORTED;
> + cookie = (__u32)value;
> +
> + if (tscookie_init((void *)hdr->tcp, hdr->tcp_len,
> + &tsopt_buf[0], &tsopt_buf[1], data_end))
> + tsopt = tsopt_buf;
> +
> + /* Check that there is enough space for a SYNACK. It also covers
> + * the check that the destination of the __builtin_memmove below
> + * doesn't overflow.
> + */
> + if (data + sizeof(*hdr->eth) + ip_len + TCP_MAXLEN > data_end)
> + return XDP_ABORTED;
> +
> + if (hdr->ipv4) {
> + if (hdr->ipv4->ihl * 4 > sizeof(*hdr->ipv4)) {
> + struct tcphdr *new_tcp_header;
> +
> + new_tcp_header = data + sizeof(*hdr->eth) + sizeof(*hdr->ipv4);
> + __builtin_memmove(new_tcp_header, hdr->tcp, sizeof(*hdr->tcp));
> + hdr->tcp = new_tcp_header;
> +
> + hdr->ipv4->ihl = sizeof(*hdr->ipv4) / 4;
> + }
> +
> + tcpv4_gen_synack(hdr, cookie, tsopt);
> + } else if (hdr->ipv6) {
> + tcpv6_gen_synack(hdr, cookie, tsopt);
> + } else {
> + return XDP_ABORTED;
> + }
> +
> + /* Recalculate checksums. */
> + hdr->tcp->check = 0;
> + value = bpf_csum_diff(0, 0, (void *)hdr->tcp, hdr->tcp_len, 0);
> + if (value < 0)
> + return XDP_ABORTED;
> + if (hdr->ipv4) {
> + hdr->tcp->check = csum_tcpudp_magic(hdr->ipv4->saddr,
> + hdr->ipv4->daddr,
> + hdr->tcp_len,
> + IPPROTO_TCP,
> + value);
> +
> + hdr->ipv4->check = 0;
> + value = bpf_csum_diff(0, 0, (void *)hdr->ipv4, sizeof(*hdr->ipv4), 0);
> + if (value < 0)
> + return XDP_ABORTED;
> + hdr->ipv4->check = csum_fold(value);
> + } else if (hdr->ipv6) {
> + hdr->tcp->check = csum_ipv6_magic(&hdr->ipv6->saddr,
> + &hdr->ipv6->daddr,
> + hdr->tcp_len,
> + IPPROTO_TCP,
> + value);
> + } else {
> + return XDP_ABORTED;
> + }
> +
> + /* Set the new packet size. */
> + old_pkt_size = data_end - data;
> + new_pkt_size = sizeof(*hdr->eth) + ip_len + hdr->tcp->doff * 4;
> + if (bpf_xdp_adjust_tail(ctx, new_pkt_size - old_pkt_size))
> + return XDP_ABORTED;
> +
> + values_inc_synacks();
> +
> + return XDP_TX;
> +}
> +
> +static __always_inline int syncookie_handle_ack(struct header_pointers *hdr)
> +{
> + int err;
> +
> + if (hdr->tcp->rst)
> + return XDP_DROP;
> +
> + if (hdr->ipv4)
> + err = bpf_tcp_raw_check_syncookie_ipv4(hdr->ipv4, hdr->tcp);
> + else if (hdr->ipv6)
> + err = bpf_tcp_raw_check_syncookie_ipv6(hdr->ipv6, hdr->tcp);
> + else
> + return XDP_ABORTED;
> + if (err)
> + return XDP_DROP;
> +
> + return XDP_PASS;
> +}
> +
> +SEC("xdp")
> +int syncookie_xdp(struct xdp_md *ctx)
> +{
> + void *data_end = (void *)(long)ctx->data_end;
> + void *data = (void *)(long)ctx->data;
> + struct header_pointers hdr;
> + __s64 value;
> + int ret;
> +
> + struct bpf_ct_opts ct_lookup_opts = {
> + .netns_id = BPF_F_CURRENT_NETNS,
> + .l4proto = IPPROTO_TCP,
> + };
> +
> + ret = tcp_dissect(data, data_end, &hdr);
> + if (ret != XDP_TX)
> + return ret;
> +
> + ret = tcp_lookup(ctx, &hdr);
> + if (ret != XDP_TX)
> + return ret;
> +
> + /* Packet is TCP and doesn't belong to an established connection. */
> +
> + if ((hdr.tcp->syn ^ hdr.tcp->ack) != 1)
> + return XDP_DROP;
> +
> + /* Grow the TCP header to TCP_MAXLEN to be able to pass any hdr.tcp_len
> + * to bpf_tcp_raw_gen_syncookie_ipv{4,6} and pass the verifier.
> + */
> + if (bpf_xdp_adjust_tail(ctx, TCP_MAXLEN - hdr.tcp_len))
> + return XDP_ABORTED;
> +
> + data_end = (void *)(long)ctx->data_end;
> + data = (void *)(long)ctx->data;
> +
> + if (hdr.ipv4) {
> + hdr.eth = data;
> + hdr.ipv4 = (void *)hdr.eth + sizeof(*hdr.eth);
> + /* IPV4_MAXLEN is needed when calculating checksum.
> + * At least sizeof(struct iphdr) is needed here to access ihl.
> + */
> + if ((void *)hdr.ipv4 + IPV4_MAXLEN > data_end)
> + return XDP_ABORTED;
> + hdr.tcp = (void *)hdr.ipv4 + hdr.ipv4->ihl * 4;
> + } else if (hdr.ipv6) {
> + hdr.eth = data;
> + hdr.ipv6 = (void *)hdr.eth + sizeof(*hdr.eth);
> + hdr.tcp = (void *)hdr.ipv6 + sizeof(*hdr.ipv6);
> + } else {
> + return XDP_ABORTED;
> + }
> +
> + if ((void *)hdr.tcp + TCP_MAXLEN > data_end)
> + return XDP_ABORTED;
> +
> + /* We run out of registers, tcp_len gets spilled to the stack, and the
> + * verifier forgets its min and max values checked above in tcp_dissect.
> + */
> + hdr.tcp_len = hdr.tcp->doff * 4;
> + if (hdr.tcp_len < sizeof(*hdr.tcp))
> + return XDP_ABORTED;
> +
> + return hdr.tcp->syn ? syncookie_handle_syn(&hdr, ctx, data, data_end) :
> + syncookie_handle_ack(&hdr);
> +}
> +
> +char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/xdp_synproxy.c b/tools/testing/selftests/bpf/xdp_synproxy.c
> new file mode 100644
> index 000000000000..4653d4655b5f
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/xdp_synproxy.c
> @@ -0,0 +1,418 @@
> +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
> +/* Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
> +
> +#include <stdnoreturn.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <unistd.h>
> +#include <getopt.h>
> +#include <signal.h>
> +#include <sys/types.h>
> +#include <bpf/bpf.h>
> +#include <bpf/libbpf.h>
> +#include <net/if.h>
> +#include <linux/if_link.h>
> +#include <linux/limits.h>
> +
> +static unsigned int ifindex;
> +static __u32 attached_prog_id;
> +
> +static void noreturn cleanup(int sig)
> +{
> + DECLARE_LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
> + int prog_fd;
> + int err;
> +
> + if (attached_prog_id == 0)
> + exit(0);
> +
> + prog_fd = bpf_prog_get_fd_by_id(attached_prog_id);
> + if (prog_fd < 0) {
> + fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd));
> + err = bpf_xdp_attach(ifindex, -1, 0, NULL);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n", strerror(-err));
> + fprintf(stderr, "Failed to detach XDP program\n");
> + exit(1);
> + }
> + } else {
> + opts.old_prog_fd = prog_fd;
> + err = bpf_xdp_attach(ifindex, -1, XDP_FLAGS_REPLACE, &opts);
> + close(prog_fd);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_set_link_xdp_fd_opts: %s\n", strerror(-err));
> + /* Not an error if already replaced by someone else. */
> + if (err != -EEXIST) {
> + fprintf(stderr, "Failed to detach XDP program\n");
> + exit(1);
> + }
> + }
> + }
> + exit(0);
> +}
> +
> +static noreturn void usage(const char *progname)
> +{
> + fprintf(stderr, "Usage: %s [--iface <iface>|--prog <prog_id>] [--mss4 <mss ipv4> --mss6 <mss ipv6> --wscale <wscale> --ttl <ttl>] [--ports <port1>,<port2>,...] [--single]\n",
> + progname);
> + exit(1);
> +}
> +
> +static unsigned long parse_arg_ul(const char *progname, const char *arg, unsigned long limit)
> +{
> + unsigned long res;
> + char *endptr;
> +
> + errno = 0;
> + res = strtoul(arg, &endptr, 10);
> + if (errno != 0 || *endptr != '\0' || arg[0] == '\0' || res > limit)
> + usage(progname);
> +
> + return res;
> +}
> +
> +static void parse_options(int argc, char *argv[], unsigned int *ifindex, __u32 *prog_id,
> + __u64 *tcpipopts, char **ports, bool *single)
> +{
> + static struct option long_options[] = {
> + { "help", no_argument, NULL, 'h' },
> + { "iface", required_argument, NULL, 'i' },
> + { "prog", required_argument, NULL, 'x' },
> + { "mss4", required_argument, NULL, 4 },
> + { "mss6", required_argument, NULL, 6 },
> + { "wscale", required_argument, NULL, 'w' },
> + { "ttl", required_argument, NULL, 't' },
> + { "ports", required_argument, NULL, 'p' },
> + { "single", no_argument, NULL, 's' },
> + { NULL, 0, NULL, 0 },
> + };
> + unsigned long mss4, mss6, wscale, ttl;
> + unsigned int tcpipopts_mask = 0;
> +
> + if (argc < 2)
> + usage(argv[0]);
> +
> + *ifindex = 0;
> + *prog_id = 0;
> + *tcpipopts = 0;
> + *ports = NULL;
> + *single = false;
> +
> + while (true) {
> + int opt;
> +
> + opt = getopt_long(argc, argv, "", long_options, NULL);
> + if (opt == -1)
> + break;
> +
> + switch (opt) {
> + case 'h':
> + usage(argv[0]);
> + break;
> + case 'i':
> + *ifindex = if_nametoindex(optarg);
> + if (*ifindex == 0)
> + usage(argv[0]);
> + break;
> + case 'x':
> + *prog_id = parse_arg_ul(argv[0], optarg, UINT32_MAX);
> + if (*prog_id == 0)
> + usage(argv[0]);
> + break;
> + case 4:
> + mss4 = parse_arg_ul(argv[0], optarg, UINT16_MAX);
> + tcpipopts_mask |= 1 << 0;
> + break;
> + case 6:
> + mss6 = parse_arg_ul(argv[0], optarg, UINT16_MAX);
> + tcpipopts_mask |= 1 << 1;
> + break;
> + case 'w':
> + wscale = parse_arg_ul(argv[0], optarg, 14);
> + tcpipopts_mask |= 1 << 2;
> + break;
> + case 't':
> + ttl = parse_arg_ul(argv[0], optarg, UINT8_MAX);
> + tcpipopts_mask |= 1 << 3;
> + break;
> + case 'p':
> + *ports = optarg;
> + break;
> + case 's':
> + *single = true;
> + break;
> + default:
> + usage(argv[0]);
> + }
> + }
> + if (optind < argc)
> + usage(argv[0]);
> +
> + if (tcpipopts_mask == 0xf) {
> + if (mss4 == 0 || mss6 == 0 || wscale == 0 || ttl == 0)
> + usage(argv[0]);
> + *tcpipopts = (mss6 << 32) | (ttl << 24) | (wscale << 16) | mss4;
> + } else if (tcpipopts_mask != 0) {
> + usage(argv[0]);
> + }
> +
> + if (*ifindex != 0 && *prog_id != 0)
> + usage(argv[0]);
> + if (*ifindex == 0 && *prog_id == 0)
> + usage(argv[0]);
> +}
> +
> +static int syncookie_attach(const char *argv0, unsigned int ifindex)
> +{
> + struct bpf_prog_info info = {};
> + __u32 info_len = sizeof(info);
> + char xdp_filename[PATH_MAX];
> + struct bpf_program *prog;
> + struct bpf_object *obj;
> + int prog_fd;
> + int err;
> +
> + snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.o", argv0);
> + obj = bpf_object__open_file(xdp_filename, NULL);
> + err = libbpf_get_error(obj);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));
> + return err;
> + }
> +
> + err = bpf_object__load(obj);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));
> + return err;
> + }
> +
> + prog = bpf_object__find_program_by_name(obj, "syncookie_xdp");
> + if (!prog) {
> + fprintf(stderr, "Error: bpf_object__find_program_by_name: program syncookie_xdp was not found\n");
> + return -ENOENT;
> + }
> +
> + prog_fd = bpf_program__fd(prog);
> +
> + err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
> + goto out;
> + }
> + attached_prog_id = info.id;
> + signal(SIGINT, cleanup);
> + signal(SIGTERM, cleanup);
> + err = bpf_xdp_attach(ifindex, prog_fd, XDP_FLAGS_UPDATE_IF_NOEXIST, NULL);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n", strerror(-err));
> + signal(SIGINT, SIG_DFL);
> + signal(SIGTERM, SIG_DFL);
> + attached_prog_id = 0;
> + goto out;
> + }
> + err = 0;
> +out:
> + bpf_object__close(obj);
> + return err;
> +}
> +
> +static int syncookie_open_bpf_maps(__u32 prog_id, int *values_map_fd, int *ports_map_fd)
> +{
> + struct bpf_prog_info prog_info;
> + __u32 map_ids[8];
> + __u32 info_len;
> + int prog_fd;
> + int err;
> + int i;
> +
> + *values_map_fd = -1;
> + *ports_map_fd = -1;
> +
> + prog_fd = bpf_prog_get_fd_by_id(prog_id);
> + if (prog_fd < 0) {
> + fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd));
> + return prog_fd;
> + }
> +
> + prog_info = (struct bpf_prog_info) {
> + .nr_map_ids = 8,
> + .map_ids = (__u64)map_ids,
> + };
> + info_len = sizeof(prog_info);
> +
> + err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len);
> + if (err != 0) {
> + fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
> + goto out;
> + }
> +
> + if (prog_info.type != BPF_PROG_TYPE_XDP) {
> + fprintf(stderr, "Error: BPF prog type is not BPF_PROG_TYPE_XDP\n");
> + err = -ENOENT;
> + goto out;
> + }
> + if (prog_info.nr_map_ids < 2) {
> + fprintf(stderr, "Error: Found %u BPF maps, expected at least 2\n",
> + prog_info.nr_map_ids);
> + err = -ENOENT;
> + goto out;
> + }
> +
> + for (i = 0; i < prog_info.nr_map_ids; i++) {
> + struct bpf_map_info map_info = {};
> + int map_fd;
> +
> + err = bpf_map_get_fd_by_id(map_ids[i]);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_map_get_fd_by_id: %s\n", strerror(-err));
> + goto err_close_map_fds;
> + }
> + map_fd = err;
> +
> + info_len = sizeof(map_info);
> + err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len);
> + if (err != 0) {
> + fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
> + close(map_fd);
> + goto err_close_map_fds;
> + }
> + if (strcmp(map_info.name, "values") == 0) {
> + *values_map_fd = map_fd;
> + continue;
> + }
> + if (strcmp(map_info.name, "allowed_ports") == 0) {
> + *ports_map_fd = map_fd;
> + continue;
> + }
> + close(map_fd);
> + }
> +
> + if (*values_map_fd != -1 && *ports_map_fd != -1) {
> + err = 0;
> + goto out;
> + }
> +
> + err = -ENOENT;
> +
> +err_close_map_fds:
> + if (*values_map_fd != -1)
> + close(*values_map_fd);
> + if (*ports_map_fd != -1)
> + close(*ports_map_fd);
> + *values_map_fd = -1;
> + *ports_map_fd = -1;
> +
> +out:
> + close(prog_fd);
> + return err;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + int values_map_fd, ports_map_fd;
> + __u64 tcpipopts;
> + bool firstiter;
> + __u64 prevcnt;
> + __u32 prog_id;
> + char *ports;
> + bool single;
> + int err = 0;
> +
> + parse_options(argc, argv, &ifindex, &prog_id, &tcpipopts, &ports, &single);
> +
> + if (prog_id == 0) {
> + err = bpf_xdp_query_id(ifindex, 0, &prog_id);
> + if (err < 0) {
> + fprintf(stderr, "Error: bpf_get_link_xdp_id: %s\n", strerror(-err));
> + goto out;
> + }
> + if (prog_id == 0) {
> + err = syncookie_attach(argv[0], ifindex);
> + if (err < 0)
> + goto out;
> + prog_id = attached_prog_id;
> + }
> + }
> +
> + err = syncookie_open_bpf_maps(prog_id, &values_map_fd, &ports_map_fd);
> + if (err < 0)
> + goto out;
> +
> + if (ports) {
> + __u16 port_last = 0;
> + __u32 port_idx = 0;
> + char *p = ports;
> +
> + fprintf(stderr, "Replacing allowed ports\n");
> +
> + while (p && *p != '\0') {
> + char *token = strsep(&p, ",");
> + __u16 port;
> +
> + port = parse_arg_ul(argv[0], token, UINT16_MAX);
> + err = bpf_map_update_elem(ports_map_fd, &port_idx, &port, BPF_ANY);
> + if (err != 0) {
> + fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
> + fprintf(stderr, "Failed to add port %u (index %u)\n",
> + port, port_idx);
> + goto out_close_maps;
> + }
> + fprintf(stderr, "Added port %u\n", port);
> + port_idx++;
> + }
> + err = bpf_map_update_elem(ports_map_fd, &port_idx, &port_last, BPF_ANY);
> + if (err != 0) {
> + fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
> + fprintf(stderr, "Failed to add the terminator value 0 (index %u)\n",
> + port_idx);
> + goto out_close_maps;
> + }
> + }
> +
> + if (tcpipopts) {
> + __u32 key = 0;
> +
> + fprintf(stderr, "Replacing TCP/IP options\n");
> +
> + err = bpf_map_update_elem(values_map_fd, &key, &tcpipopts, BPF_ANY);
> + if (err != 0) {
> + fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
> + goto out_close_maps;
> + }
> + }
> +
> + if ((ports || tcpipopts) && attached_prog_id == 0 && !single)
> + goto out_close_maps;
> +
> + prevcnt = 0;
> + firstiter = true;
> + while (true) {
> + __u32 key = 1;
> + __u64 value;
> +
> + err = bpf_map_lookup_elem(values_map_fd, &key, &value);
> + if (err != 0) {
> + fprintf(stderr, "Error: bpf_map_lookup_elem: %s\n", strerror(-err));
> + goto out_close_maps;
> + }
> + if (firstiter) {
> + prevcnt = value;
> + firstiter = false;
> + }
> + if (single) {
> + printf("Total SYNACKs generated: %llu\n", value);
> + break;
> + }
> + printf("SYNACKs generated: %llu (total %llu)\n", value - prevcnt, value);
> + prevcnt = value;
> + sleep(1);
> + }
> +
> +out_close_maps:
> + close(values_map_fd);
> + close(ports_map_fd);
> +out:
> + return err == 0 ? 0 : 1;
> +}
> --
> 2.30.2
>
--
WBR, Yauheni
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