diff options
author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-01-15 23:55:14 +0300 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-24 01:40:24 +0300 |
commit | a74712241b4675175cd8e3310fa206d8756ad5a1 (patch) | |
tree | e9af2ccb810881632330d014ecc83b1726537a16 /tools | |
parent | e472f88891abbc535a5e16a68a104073985f6061 (diff) | |
download | linux-a74712241b4675175cd8e3310fa206d8756ad5a1.tar.xz |
selftest: bpf: Test bpf_sk_assign_tcp_reqsk().
This commit adds a sample selftest to demonstrate how we can use
bpf_sk_assign_tcp_reqsk() as the backend of SYN Proxy.
The test creates IPv4/IPv6 x TCP connections and transfer messages
over them on lo with BPF tc prog attached.
The tc prog will process SYN and returns SYN+ACK with the following
ISN and TS. In a real use case, this part will be done by other
hosts.
MSB LSB
ISN: | 31 ... 8 | 7 6 | 5 | 4 | 3 2 1 0 |
| Hash_1 | MSS | ECN | SACK | WScale |
TS: | 31 ... 8 | 7 ... 0 |
| Random | Hash_2 |
WScale in SYN is reused in SYN+ACK.
The client returns ACK, and tc prog will recalculate ISN and TS
from ACK and validate SYN Cookie.
If it's valid, the prog calls kfunc to allocate a reqsk for skb and
configure the reqsk based on the argument created from SYN Cookie.
Later, the reqsk will be processed in cookie_v[46]_check() to create
a connection.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240115205514.68364-7-kuniyu@amazon.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools')
-rw-r--r-- | tools/testing/selftests/bpf/bpf_kfuncs.h | 10 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/config | 1 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c | 150 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/bpf_tracing_net.h | 16 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/test_siphash.h | 64 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.c | 572 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.h | 140 |
7 files changed, 953 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h index b4e78c1eb37b..23c24f852f4f 100644 --- a/tools/testing/selftests/bpf/bpf_kfuncs.h +++ b/tools/testing/selftests/bpf/bpf_kfuncs.h @@ -51,6 +51,16 @@ extern int bpf_dynptr_clone(const struct bpf_dynptr *ptr, struct bpf_dynptr *clo extern int bpf_sock_addr_set_sun_path(struct bpf_sock_addr_kern *sa_kern, const __u8 *sun_path, __u32 sun_path__sz) __ksym; +/* Description + * Allocate and configure a reqsk and link it with a listener and skb. + * Returns + * Error code + */ +struct sock; +struct bpf_tcp_req_attrs; +extern int bpf_sk_assign_tcp_reqsk(struct __sk_buff *skb, struct sock *sk, + struct bpf_tcp_req_attrs *attrs, int attrs__sz) __ksym; + void *bpf_cast_to_kern_ctx(void *) __ksym; void *bpf_rdonly_cast(void *obj, __u32 btf_id) __ksym; diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config index c125c441abc7..01f241ea2c67 100644 --- a/tools/testing/selftests/bpf/config +++ b/tools/testing/selftests/bpf/config @@ -81,6 +81,7 @@ CONFIG_NF_NAT=y CONFIG_RC_CORE=y CONFIG_SECURITY=y CONFIG_SECURITYFS=y +CONFIG_SYN_COOKIES=y CONFIG_TEST_BPF=m CONFIG_USERFAULTFD=y CONFIG_VSOCKETS=y diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c b/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c new file mode 100644 index 000000000000..eaf441dc7e79 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright Amazon.com Inc. or its affiliates. */ + +#define _GNU_SOURCE +#include <sched.h> +#include <stdlib.h> +#include <net/if.h> + +#include "test_progs.h" +#include "cgroup_helpers.h" +#include "network_helpers.h" +#include "test_tcp_custom_syncookie.skel.h" + +static struct test_tcp_custom_syncookie_case { + int family, type; + char addr[16]; + char name[10]; +} test_cases[] = { + { + .name = "IPv4 TCP", + .family = AF_INET, + .type = SOCK_STREAM, + .addr = "127.0.0.1", + }, + { + .name = "IPv6 TCP", + .family = AF_INET6, + .type = SOCK_STREAM, + .addr = "::1", + }, +}; + +static int setup_netns(void) +{ + if (!ASSERT_OK(unshare(CLONE_NEWNET), "create netns")) + return -1; + + if (!ASSERT_OK(system("ip link set dev lo up"), "ip")) + goto err; + + if (!ASSERT_OK(write_sysctl("/proc/sys/net/ipv4/tcp_ecn", "1"), + "write_sysctl")) + goto err; + + return 0; +err: + return -1; +} + +static int setup_tc(struct test_tcp_custom_syncookie *skel) +{ + LIBBPF_OPTS(bpf_tc_hook, qdisc_lo, .attach_point = BPF_TC_INGRESS); + LIBBPF_OPTS(bpf_tc_opts, tc_attach, + .prog_fd = bpf_program__fd(skel->progs.tcp_custom_syncookie)); + + qdisc_lo.ifindex = if_nametoindex("lo"); + if (!ASSERT_OK(bpf_tc_hook_create(&qdisc_lo), "qdisc add dev lo clsact")) + goto err; + + if (!ASSERT_OK(bpf_tc_attach(&qdisc_lo, &tc_attach), + "filter add dev lo ingress")) + goto err; + + return 0; +err: + return -1; +} + +#define msg "Hello World" +#define msglen 11 + +static void transfer_message(int sender, int receiver) +{ + char buf[msglen]; + int ret; + + ret = send(sender, msg, msglen, 0); + if (!ASSERT_EQ(ret, msglen, "send")) + return; + + memset(buf, 0, sizeof(buf)); + + ret = recv(receiver, buf, msglen, 0); + if (!ASSERT_EQ(ret, msglen, "recv")) + return; + + ret = strncmp(buf, msg, msglen); + if (!ASSERT_EQ(ret, 0, "strncmp")) + return; +} + +static void create_connection(struct test_tcp_custom_syncookie_case *test_case) +{ + int server, client, child; + + server = start_server(test_case->family, test_case->type, test_case->addr, 0, 0); + if (!ASSERT_NEQ(server, -1, "start_server")) + return; + + client = connect_to_fd(server, 0); + if (!ASSERT_NEQ(client, -1, "connect_to_fd")) + goto close_server; + + child = accept(server, NULL, 0); + if (!ASSERT_NEQ(child, -1, "accept")) + goto close_client; + + transfer_message(client, child); + transfer_message(child, client); + + close(child); +close_client: + close(client); +close_server: + close(server); +} + +void test_tcp_custom_syncookie(void) +{ + struct test_tcp_custom_syncookie *skel; + int i; + + if (setup_netns()) + return; + + skel = test_tcp_custom_syncookie__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_and_load")) + return; + + if (setup_tc(skel)) + goto destroy_skel; + + for (i = 0; i < ARRAY_SIZE(test_cases); i++) { + if (!test__start_subtest(test_cases[i].name)) + continue; + + skel->bss->handled_syn = false; + skel->bss->handled_ack = false; + + create_connection(&test_cases[i]); + + ASSERT_EQ(skel->bss->handled_syn, true, "SYN is not handled at tc."); + ASSERT_EQ(skel->bss->handled_ack, true, "ACK is not handled at tc"); + } + +destroy_skel: + system("tc qdisc del dev lo clsact"); + + test_tcp_custom_syncookie__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h index e8bd4b7b5ef7..7001965d1cc3 100644 --- a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h +++ b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h @@ -51,9 +51,25 @@ #define ICSK_TIME_LOSS_PROBE 5 #define ICSK_TIME_REO_TIMEOUT 6 +#define ETH_ALEN 6 #define ETH_HLEN 14 +#define ETH_P_IP 0x0800 #define ETH_P_IPV6 0x86DD +#define NEXTHDR_TCP 6 + +#define TCPOPT_NOP 1 +#define TCPOPT_EOL 0 +#define TCPOPT_MSS 2 +#define TCPOPT_WINDOW 3 +#define TCPOPT_TIMESTAMP 8 +#define TCPOPT_SACK_PERM 4 + +#define TCPOLEN_MSS 4 +#define TCPOLEN_WINDOW 3 +#define TCPOLEN_TIMESTAMP 10 +#define TCPOLEN_SACK_PERM 2 + #define CHECKSUM_NONE 0 #define CHECKSUM_PARTIAL 3 diff --git a/tools/testing/selftests/bpf/progs/test_siphash.h b/tools/testing/selftests/bpf/progs/test_siphash.h new file mode 100644 index 000000000000..5d3a7ec36780 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_siphash.h @@ -0,0 +1,64 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright Amazon.com Inc. or its affiliates. */ + +#ifndef _TEST_SIPHASH_H +#define _TEST_SIPHASH_H + +/* include/linux/bitops.h */ +static inline u64 rol64(u64 word, unsigned int shift) +{ + return (word << (shift & 63)) | (word >> ((-shift) & 63)); +} + +/* include/linux/siphash.h */ +#define SIPHASH_PERMUTATION(a, b, c, d) ( \ + (a) += (b), (b) = rol64((b), 13), (b) ^= (a), (a) = rol64((a), 32), \ + (c) += (d), (d) = rol64((d), 16), (d) ^= (c), \ + (a) += (d), (d) = rol64((d), 21), (d) ^= (a), \ + (c) += (b), (b) = rol64((b), 17), (b) ^= (c), (c) = rol64((c), 32)) + +#define SIPHASH_CONST_0 0x736f6d6570736575ULL +#define SIPHASH_CONST_1 0x646f72616e646f6dULL +#define SIPHASH_CONST_2 0x6c7967656e657261ULL +#define SIPHASH_CONST_3 0x7465646279746573ULL + +/* lib/siphash.c */ +#define SIPROUND SIPHASH_PERMUTATION(v0, v1, v2, v3) + +#define PREAMBLE(len) \ + u64 v0 = SIPHASH_CONST_0; \ + u64 v1 = SIPHASH_CONST_1; \ + u64 v2 = SIPHASH_CONST_2; \ + u64 v3 = SIPHASH_CONST_3; \ + u64 b = ((u64)(len)) << 56; \ + v3 ^= key->key[1]; \ + v2 ^= key->key[0]; \ + v1 ^= key->key[1]; \ + v0 ^= key->key[0]; + +#define POSTAMBLE \ + v3 ^= b; \ + SIPROUND; \ + SIPROUND; \ + v0 ^= b; \ + v2 ^= 0xff; \ + SIPROUND; \ + SIPROUND; \ + SIPROUND; \ + SIPROUND; \ + return (v0 ^ v1) ^ (v2 ^ v3); + +static inline u64 siphash_2u64(const u64 first, const u64 second, const siphash_key_t *key) +{ + PREAMBLE(16) + v3 ^= first; + SIPROUND; + SIPROUND; + v0 ^= first; + v3 ^= second; + SIPROUND; + SIPROUND; + v0 ^= second; + POSTAMBLE +} +#endif diff --git a/tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.c b/tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.c new file mode 100644 index 000000000000..a5501b29979a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.c @@ -0,0 +1,572 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright Amazon.com Inc. or its affiliates. */ + +#include "vmlinux.h" + +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_endian.h> +#include "bpf_tracing_net.h" +#include "bpf_kfuncs.h" +#include "test_siphash.h" +#include "test_tcp_custom_syncookie.h" + +/* Hash is calculated for each client and split into ISN and TS. + * + * MSB LSB + * ISN: | 31 ... 8 | 7 6 | 5 | 4 | 3 2 1 0 | + * | Hash_1 | MSS | ECN | SACK | WScale | + * + * TS: | 31 ... 8 | 7 ... 0 | + * | Random | Hash_2 | + */ +#define COOKIE_BITS 8 +#define COOKIE_MASK (((__u32)1 << COOKIE_BITS) - 1) + +enum { + /* 0xf is invalid thus means that SYN did not have WScale. */ + BPF_SYNCOOKIE_WSCALE_MASK = (1 << 4) - 1, + BPF_SYNCOOKIE_SACK = (1 << 4), + BPF_SYNCOOKIE_ECN = (1 << 5), +}; + +#define MSS_LOCAL_IPV4 65495 +#define MSS_LOCAL_IPV6 65476 + +const __u16 msstab4[] = { + 536, + 1300, + 1460, + MSS_LOCAL_IPV4, +}; + +const __u16 msstab6[] = { + 1280 - 60, /* IPV6_MIN_MTU - 60 */ + 1480 - 60, + 9000 - 60, + MSS_LOCAL_IPV6, +}; + +static siphash_key_t test_key_siphash = { + { 0x0706050403020100ULL, 0x0f0e0d0c0b0a0908ULL } +}; + +struct tcp_syncookie { + struct __sk_buff *skb; + void *data_end; + struct ethhdr *eth; + struct iphdr *ipv4; + struct ipv6hdr *ipv6; + struct tcphdr *tcp; + union { + char *ptr; + __be32 *ptr32; + }; + struct bpf_tcp_req_attrs attrs; + u32 cookie; + u64 first; +}; + +bool handled_syn, handled_ack; + +static int tcp_load_headers(struct tcp_syncookie *ctx) +{ + ctx->data_end = (void *)(long)ctx->skb->data_end; + ctx->eth = (struct ethhdr *)(long)ctx->skb->data; + + if (ctx->eth + 1 > ctx->data_end) + goto err; + + switch (bpf_ntohs(ctx->eth->h_proto)) { + case ETH_P_IP: + ctx->ipv4 = (struct iphdr *)(ctx->eth + 1); + + if (ctx->ipv4 + 1 > ctx->data_end) + goto err; + + if (ctx->ipv4->ihl != sizeof(*ctx->ipv4) / 4) + goto err; + + if (ctx->ipv4->version != 4) + goto err; + + if (ctx->ipv4->protocol != IPPROTO_TCP) + goto err; + + ctx->tcp = (struct tcphdr *)(ctx->ipv4 + 1); + break; + case ETH_P_IPV6: + ctx->ipv6 = (struct ipv6hdr *)(ctx->eth + 1); + + if (ctx->ipv6 + 1 > ctx->data_end) + goto err; + + if (ctx->ipv6->version != 6) + goto err; + + if (ctx->ipv6->nexthdr != NEXTHDR_TCP) + goto err; + + ctx->tcp = (struct tcphdr *)(ctx->ipv6 + 1); + break; + default: + goto err; + } + + if (ctx->tcp + 1 > ctx->data_end) + goto err; + + return 0; +err: + return -1; +} + +static int tcp_reload_headers(struct tcp_syncookie *ctx) +{ + /* Without volatile, + * R3 32-bit pointer arithmetic prohibited + */ + volatile u64 data_len = ctx->skb->data_end - ctx->skb->data; + + if (ctx->tcp->doff < sizeof(*ctx->tcp) / 4) + goto err; + + /* Needed to calculate csum and parse TCP options. */ + if (bpf_skb_change_tail(ctx->skb, data_len + 60 - ctx->tcp->doff * 4, 0)) + goto err; + + ctx->data_end = (void *)(long)ctx->skb->data_end; + ctx->eth = (struct ethhdr *)(long)ctx->skb->data; + if (ctx->ipv4) { + ctx->ipv4 = (struct iphdr *)(ctx->eth + 1); + ctx->ipv6 = NULL; + ctx->tcp = (struct tcphdr *)(ctx->ipv4 + 1); + } else { + ctx->ipv4 = NULL; + ctx->ipv6 = (struct ipv6hdr *)(ctx->eth + 1); + ctx->tcp = (struct tcphdr *)(ctx->ipv6 + 1); + } + + if ((void *)ctx->tcp + 60 > ctx->data_end) + goto err; + + return 0; +err: + return -1; +} + +static __sum16 tcp_v4_csum(struct tcp_syncookie *ctx, __wsum csum) +{ + return csum_tcpudp_magic(ctx->ipv4->saddr, ctx->ipv4->daddr, + ctx->tcp->doff * 4, IPPROTO_TCP, csum); +} + +static __sum16 tcp_v6_csum(struct tcp_syncookie *ctx, __wsum csum) +{ + return csum_ipv6_magic(&ctx->ipv6->saddr, &ctx->ipv6->daddr, + ctx->tcp->doff * 4, IPPROTO_TCP, csum); +} + +static int tcp_validate_header(struct tcp_syncookie *ctx) +{ + s64 csum; + + if (tcp_reload_headers(ctx)) + goto err; + + csum = bpf_csum_diff(0, 0, (void *)ctx->tcp, ctx->tcp->doff * 4, 0); + if (csum < 0) + goto err; + + if (ctx->ipv4) { + /* check tcp_v4_csum(csum) is 0 if not on lo. */ + + csum = bpf_csum_diff(0, 0, (void *)ctx->ipv4, ctx->ipv4->ihl * 4, 0); + if (csum < 0) + goto err; + + if (csum_fold(csum) != 0) + goto err; + } else if (ctx->ipv6) { + /* check tcp_v6_csum(csum) is 0 if not on lo. */ + } + + return 0; +err: + return -1; +} + +static int tcp_parse_option(__u32 index, struct tcp_syncookie *ctx) +{ + char opcode, opsize; + + if (ctx->ptr + 1 > ctx->data_end) + goto stop; + + opcode = *ctx->ptr++; + + if (opcode == TCPOPT_EOL) + goto stop; + + if (opcode == TCPOPT_NOP) + goto next; + + if (ctx->ptr + 1 > ctx->data_end) + goto stop; + + opsize = *ctx->ptr++; + + if (opsize < 2) + goto stop; + + switch (opcode) { + case TCPOPT_MSS: + if (opsize == TCPOLEN_MSS && ctx->tcp->syn && + ctx->ptr + (TCPOLEN_MSS - 2) < ctx->data_end) + ctx->attrs.mss = get_unaligned_be16(ctx->ptr); + break; + case TCPOPT_WINDOW: + if (opsize == TCPOLEN_WINDOW && ctx->tcp->syn && + ctx->ptr + (TCPOLEN_WINDOW - 2) < ctx->data_end) { + ctx->attrs.wscale_ok = 1; + ctx->attrs.snd_wscale = *ctx->ptr; + } + break; + case TCPOPT_TIMESTAMP: + if (opsize == TCPOLEN_TIMESTAMP && + ctx->ptr + (TCPOLEN_TIMESTAMP - 2) < ctx->data_end) { + ctx->attrs.rcv_tsval = get_unaligned_be32(ctx->ptr); + ctx->attrs.rcv_tsecr = get_unaligned_be32(ctx->ptr + 4); + + if (ctx->tcp->syn && ctx->attrs.rcv_tsecr) + ctx->attrs.tstamp_ok = 0; + else + ctx->attrs.tstamp_ok = 1; + } + break; + case TCPOPT_SACK_PERM: + if (opsize == TCPOLEN_SACK_PERM && ctx->tcp->syn && + ctx->ptr + (TCPOLEN_SACK_PERM - 2) < ctx->data_end) + ctx->attrs.sack_ok = 1; + break; + } + + ctx->ptr += opsize - 2; +next: + return 0; +stop: + return 1; +} + +static void tcp_parse_options(struct tcp_syncookie *ctx) +{ + ctx->ptr = (char *)(ctx->tcp + 1); + + bpf_loop(40, tcp_parse_option, ctx, 0); +} + +static int tcp_validate_sysctl(struct tcp_syncookie *ctx) +{ + if ((ctx->ipv4 && ctx->attrs.mss != MSS_LOCAL_IPV4) || + (ctx->ipv6 && ctx->attrs.mss != MSS_LOCAL_IPV6)) + goto err; + + if (!ctx->attrs.wscale_ok || ctx->attrs.snd_wscale != 7) + goto err; + + if (!ctx->attrs.tstamp_ok) + goto err; + + if (!ctx->attrs.sack_ok) + goto err; + + if (!ctx->tcp->ece || !ctx->tcp->cwr) + goto err; + + return 0; +err: + return -1; +} + +static void tcp_prepare_cookie(struct tcp_syncookie *ctx) +{ + u32 seq = bpf_ntohl(ctx->tcp->seq); + u64 first = 0, second; + int mssind = 0; + u32 hash; + + if (ctx->ipv4) { + for (mssind = ARRAY_SIZE(msstab4) - 1; mssind; mssind--) + if (ctx->attrs.mss >= msstab4[mssind]) + break; + + ctx->attrs.mss = msstab4[mssind]; + + first = (u64)ctx->ipv4->saddr << 32 | ctx->ipv4->daddr; + } else if (ctx->ipv6) { + for (mssind = ARRAY_SIZE(msstab6) - 1; mssind; mssind--) + if (ctx->attrs.mss >= msstab6[mssind]) + break; + + ctx->attrs.mss = msstab6[mssind]; + + first = (u64)ctx->ipv6->saddr.in6_u.u6_addr8[0] << 32 | + ctx->ipv6->daddr.in6_u.u6_addr32[0]; + } + + second = (u64)seq << 32 | ctx->tcp->source << 16 | ctx->tcp->dest; + hash = siphash_2u64(first, second, &test_key_siphash); + + if (ctx->attrs.tstamp_ok) { + ctx->attrs.rcv_tsecr = bpf_get_prandom_u32(); + ctx->attrs.rcv_tsecr &= ~COOKIE_MASK; + ctx->attrs.rcv_tsecr |= hash & COOKIE_MASK; + } + + hash &= ~COOKIE_MASK; + hash |= mssind << 6; + + if (ctx->attrs.wscale_ok) + hash |= ctx->attrs.snd_wscale & BPF_SYNCOOKIE_WSCALE_MASK; + + if (ctx->attrs.sack_ok) + hash |= BPF_SYNCOOKIE_SACK; + + if (ctx->attrs.tstamp_ok && ctx->tcp->ece && ctx->tcp->cwr) + hash |= BPF_SYNCOOKIE_ECN; + + ctx->cookie = hash; +} + +static void tcp_write_options(struct tcp_syncookie *ctx) +{ + ctx->ptr32 = (__be32 *)(ctx->tcp + 1); + + *ctx->ptr32++ = bpf_htonl(TCPOPT_MSS << 24 | TCPOLEN_MSS << 16 | + ctx->attrs.mss); + + if (ctx->attrs.wscale_ok) + *ctx->ptr32++ = bpf_htonl(TCPOPT_NOP << 24 | + TCPOPT_WINDOW << 16 | + TCPOLEN_WINDOW << 8 | + ctx->attrs.snd_wscale); + + if (ctx->attrs.tstamp_ok) { + if (ctx->attrs.sack_ok) + *ctx->ptr32++ = bpf_htonl(TCPOPT_SACK_PERM << 24 | + TCPOLEN_SACK_PERM << 16 | + TCPOPT_TIMESTAMP << 8 | + TCPOLEN_TIMESTAMP); + else + *ctx->ptr32++ = bpf_htonl(TCPOPT_NOP << 24 | + TCPOPT_NOP << 16 | + TCPOPT_TIMESTAMP << 8 | + TCPOLEN_TIMESTAMP); + + *ctx->ptr32++ = bpf_htonl(ctx->attrs.rcv_tsecr); + *ctx->ptr32++ = bpf_htonl(ctx->attrs.rcv_tsval); + } else if (ctx->attrs.sack_ok) { + *ctx->ptr32++ = bpf_htonl(TCPOPT_NOP << 24 | + TCPOPT_NOP << 16 | + TCPOPT_SACK_PERM << 8 | + TCPOLEN_SACK_PERM); + } +} + +static int tcp_handle_syn(struct tcp_syncookie *ctx) +{ + s64 csum; + + if (tcp_validate_header(ctx)) + goto err; + + tcp_parse_options(ctx); + + if (tcp_validate_sysctl(ctx)) + goto err; + + tcp_prepare_cookie(ctx); + tcp_write_options(ctx); + + swap(ctx->tcp->source, ctx->tcp->dest); + ctx->tcp->check = 0; + ctx->tcp->ack_seq = bpf_htonl(bpf_ntohl(ctx->tcp->seq) + 1); + ctx->tcp->seq = bpf_htonl(ctx->cookie); + ctx->tcp->doff = ((long)ctx->ptr32 - (long)ctx->tcp) >> 2; + ctx->tcp->ack = 1; + if (!ctx->attrs.tstamp_ok || !ctx->tcp->ece || !ctx->tcp->cwr) + ctx->tcp->ece = 0; + ctx->tcp->cwr = 0; + + csum = bpf_csum_diff(0, 0, (void *)ctx->tcp, ctx->tcp->doff * 4, 0); + if (csum < 0) + goto err; + + if (ctx->ipv4) { + swap(ctx->ipv4->saddr, ctx->ipv4->daddr); + ctx->tcp->check = tcp_v4_csum(ctx, csum); + + ctx->ipv4->check = 0; + ctx->ipv4->tos = 0; + ctx->ipv4->tot_len = bpf_htons((long)ctx->ptr32 - (long)ctx->ipv4); + ctx->ipv4->id = 0; + ctx->ipv4->ttl = 64; + + csum = bpf_csum_diff(0, 0, (void *)ctx->ipv4, sizeof(*ctx->ipv4), 0); + if (csum < 0) + goto err; + + ctx->ipv4->check = csum_fold(csum); + } else if (ctx->ipv6) { + swap(ctx->ipv6->saddr, ctx->ipv6->daddr); + ctx->tcp->check = tcp_v6_csum(ctx, csum); + + *(__be32 *)ctx->ipv6 = bpf_htonl(0x60000000); + ctx->ipv6->payload_len = bpf_htons((long)ctx->ptr32 - (long)ctx->tcp); + ctx->ipv6->hop_limit = 64; + } + + swap_array(ctx->eth->h_source, ctx->eth->h_dest); + + if (bpf_skb_change_tail(ctx->skb, (long)ctx->ptr32 - (long)ctx->eth, 0)) + goto err; + + return bpf_redirect(ctx->skb->ifindex, 0); +err: + return TC_ACT_SHOT; +} + +static int tcp_validate_cookie(struct tcp_syncookie *ctx) +{ + u32 cookie = bpf_ntohl(ctx->tcp->ack_seq) - 1; + u32 seq = bpf_ntohl(ctx->tcp->seq) - 1; + u64 first = 0, second; + int mssind; + u32 hash; + + if (ctx->ipv4) + first = (u64)ctx->ipv4->saddr << 32 | ctx->ipv4->daddr; + else if (ctx->ipv6) + first = (u64)ctx->ipv6->saddr.in6_u.u6_addr8[0] << 32 | + ctx->ipv6->daddr.in6_u.u6_addr32[0]; + + second = (u64)seq << 32 | ctx->tcp->source << 16 | ctx->tcp->dest; + hash = siphash_2u64(first, second, &test_key_siphash); + + if (ctx->attrs.tstamp_ok) + hash -= ctx->attrs.rcv_tsecr & COOKIE_MASK; + else + hash &= ~COOKIE_MASK; + + hash -= cookie & ~COOKIE_MASK; + if (hash) + goto err; + + mssind = (cookie & (3 << 6)) >> 6; + if (ctx->ipv4) { + if (mssind > ARRAY_SIZE(msstab4)) + goto err; + + ctx->attrs.mss = msstab4[mssind]; + } else { + if (mssind > ARRAY_SIZE(msstab6)) + goto err; + + ctx->attrs.mss = msstab6[mssind]; + } + + ctx->attrs.snd_wscale = cookie & BPF_SYNCOOKIE_WSCALE_MASK; + ctx->attrs.rcv_wscale = ctx->attrs.snd_wscale; + ctx->attrs.wscale_ok = ctx->attrs.snd_wscale == BPF_SYNCOOKIE_WSCALE_MASK; + ctx->attrs.sack_ok = cookie & BPF_SYNCOOKIE_SACK; + ctx->attrs.ecn_ok = cookie & BPF_SYNCOOKIE_ECN; + + return 0; +err: + return -1; +} + +static int tcp_handle_ack(struct tcp_syncookie *ctx) +{ + struct bpf_sock_tuple tuple; + struct bpf_sock *skc; + int ret = TC_ACT_OK; + struct sock *sk; + u32 tuple_size; + + if (ctx->ipv4) { + tuple.ipv4.saddr = ctx->ipv4->saddr; + tuple.ipv4.daddr = ctx->ipv4->daddr; + tuple.ipv4.sport = ctx->tcp->source; + tuple.ipv4.dport = ctx->tcp->dest; + tuple_size = sizeof(tuple.ipv4); + } else if (ctx->ipv6) { + __builtin_memcpy(tuple.ipv6.saddr, &ctx->ipv6->saddr, sizeof(tuple.ipv6.saddr)); + __builtin_memcpy(tuple.ipv6.daddr, &ctx->ipv6->daddr, sizeof(tuple.ipv6.daddr)); + tuple.ipv6.sport = ctx->tcp->source; + tuple.ipv6.dport = ctx->tcp->dest; + tuple_size = sizeof(tuple.ipv6); + } else { + goto out; + } + + skc = bpf_skc_lookup_tcp(ctx->skb, &tuple, tuple_size, -1, 0); + if (!skc) + goto out; + + if (skc->state != TCP_LISTEN) + goto release; + + sk = (struct sock *)bpf_skc_to_tcp_sock(skc); + if (!sk) + goto err; + + if (tcp_validate_header(ctx)) + goto err; + + tcp_parse_options(ctx); + + if (tcp_validate_cookie(ctx)) + goto err; + + ret = bpf_sk_assign_tcp_reqsk(ctx->skb, sk, &ctx->attrs, sizeof(ctx->attrs)); + if (ret < 0) + goto err; + +release: + bpf_sk_release(skc); +out: + return ret; + +err: + ret = TC_ACT_SHOT; + goto release; +} + +SEC("tc") +int tcp_custom_syncookie(struct __sk_buff *skb) +{ + struct tcp_syncookie ctx = { + .skb = skb, + }; + + if (tcp_load_headers(&ctx)) + return TC_ACT_OK; + + if (ctx.tcp->rst) + return TC_ACT_OK; + + if (ctx.tcp->syn) { + if (ctx.tcp->ack) + return TC_ACT_OK; + + handled_syn = true; + + return tcp_handle_syn(&ctx); + } + + handled_ack = true; + + return tcp_handle_ack(&ctx); +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.h b/tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.h new file mode 100644 index 000000000000..29a6a53cf229 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.h @@ -0,0 +1,140 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright Amazon.com Inc. or its affiliates. */ + +#ifndef _TEST_TCP_SYNCOOKIE_H +#define _TEST_TCP_SYNCOOKIE_H + +#define __packed __attribute__((__packed__)) +#define __force + +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) + +#define swap(a, b) \ + do { \ + typeof(a) __tmp = (a); \ + (a) = (b); \ + (b) = __tmp; \ + } while (0) + +#define swap_array(a, b) \ + do { \ + typeof(a) __tmp[sizeof(a)]; \ + __builtin_memcpy(__tmp, a, sizeof(a)); \ + __builtin_memcpy(a, b, sizeof(a)); \ + __builtin_memcpy(b, __tmp, sizeof(a)); \ + } while (0) + +/* asm-generic/unaligned.h */ +#define __get_unaligned_t(type, ptr) ({ \ + const struct { type x; } __packed * __pptr = (typeof(__pptr))(ptr); \ + __pptr->x; \ +}) + +#define get_unaligned(ptr) __get_unaligned_t(typeof(*(ptr)), (ptr)) + +static inline u16 get_unaligned_be16(const void *p) +{ + return bpf_ntohs(__get_unaligned_t(__be16, p)); +} + +static inline u32 get_unaligned_be32(const void *p) +{ + return bpf_ntohl(__get_unaligned_t(__be32, p)); +} + +/* lib/checksum.c */ +static inline u32 from64to32(u64 x) +{ + /* add up 32-bit and 32-bit for 32+c bit */ + x = (x & 0xffffffff) + (x >> 32); + /* add up carry.. */ + x = (x & 0xffffffff) + (x >> 32); + return (u32)x; +} + +static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, + __u32 len, __u8 proto, __wsum sum) +{ + unsigned long long s = (__force u32)sum; + + s += (__force u32)saddr; + s += (__force u32)daddr; +#ifdef __BIG_ENDIAN + s += proto + len; +#else + s += (proto + len) << 8; +#endif + return (__force __wsum)from64to32(s); +} + +/* asm-generic/checksum.h */ +static inline __sum16 csum_fold(__wsum csum) +{ + u32 sum = (__force u32)csum; + + sum = (sum & 0xffff) + (sum >> 16); + sum = (sum & 0xffff) + (sum >> 16); + return (__force __sum16)~sum; +} + +static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, + __u8 proto, __wsum sum) +{ + return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum)); +} + +/* net/ipv6/ip6_checksum.c */ +static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr, + const struct in6_addr *daddr, + __u32 len, __u8 proto, __wsum csum) +{ + int carry; + __u32 ulen; + __u32 uproto; + __u32 sum = (__force u32)csum; + + sum += (__force u32)saddr->in6_u.u6_addr32[0]; + carry = (sum < (__force u32)saddr->in6_u.u6_addr32[0]); + sum += carry; + + sum += (__force u32)saddr->in6_u.u6_addr32[1]; + carry = (sum < (__force u32)saddr->in6_u.u6_addr32[1]); + sum += carry; + + sum += (__force u32)saddr->in6_u.u6_addr32[2]; + carry = (sum < (__force u32)saddr->in6_u.u6_addr32[2]); + sum += carry; + + sum += (__force u32)saddr->in6_u.u6_addr32[3]; + carry = (sum < (__force u32)saddr->in6_u.u6_addr32[3]); + sum += carry; + + sum += (__force u32)daddr->in6_u.u6_addr32[0]; + carry = (sum < (__force u32)daddr->in6_u.u6_addr32[0]); + sum += carry; + + sum += (__force u32)daddr->in6_u.u6_addr32[1]; + carry = (sum < (__force u32)daddr->in6_u.u6_addr32[1]); + sum += carry; + + sum += (__force u32)daddr->in6_u.u6_addr32[2]; + carry = (sum < (__force u32)daddr->in6_u.u6_addr32[2]); + sum += carry; + + sum += (__force u32)daddr->in6_u.u6_addr32[3]; + carry = (sum < (__force u32)daddr->in6_u.u6_addr32[3]); + sum += carry; + + ulen = (__force u32)bpf_htonl((__u32)len); + sum += ulen; + carry = (sum < ulen); + sum += carry; + + uproto = (__force u32)bpf_htonl(proto); + sum += uproto; + carry = (sum < uproto); + sum += carry; + + return csum_fold((__force __wsum)sum); +} +#endif |