209 lines · c
1// SPDX-License-Identifier: GPL-2.02// Copyright (c) 2018 Facebook3 4#include <string.h>5 6#include <linux/stddef.h>7#include <linux/bpf.h>8#include <linux/in.h>9#include <linux/in6.h>10#include <linux/tcp.h>11#include <linux/if.h>12#include <errno.h>13 14#include <bpf/bpf_helpers.h>15#include <bpf/bpf_endian.h>16 17#define SRC_REWRITE_IP4 0x7f000004U18#define DST_REWRITE_IP4 0x7f000001U19#define DST_REWRITE_PORT4 444420 21#ifndef TCP_CA_NAME_MAX22#define TCP_CA_NAME_MAX 1623#endif24 25#ifndef TCP_NOTSENT_LOWAT26#define TCP_NOTSENT_LOWAT 2527#endif28 29#ifndef IFNAMSIZ30#define IFNAMSIZ 1631#endif32 33#ifndef SOL_TCP34#define SOL_TCP 635#endif36 37__attribute__ ((noinline)) __weak38int do_bind(struct bpf_sock_addr *ctx)39{40 struct sockaddr_in sa = {};41 42 sa.sin_family = AF_INET;43 sa.sin_port = bpf_htons(0);44 sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);45 46 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)47 return 0;48 49 return 1;50}51 52static __inline int verify_cc(struct bpf_sock_addr *ctx,53 char expected[TCP_CA_NAME_MAX])54{55 char buf[TCP_CA_NAME_MAX];56 int i;57 58 if (bpf_getsockopt(ctx, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf)))59 return 1;60 61 for (i = 0; i < TCP_CA_NAME_MAX; i++) {62 if (buf[i] != expected[i])63 return 1;64 if (buf[i] == 0)65 break;66 }67 68 return 0;69}70 71static __inline int set_cc(struct bpf_sock_addr *ctx)72{73 char reno[TCP_CA_NAME_MAX] = "reno";74 char cubic[TCP_CA_NAME_MAX] = "cubic";75 76 if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &reno, sizeof(reno)))77 return 1;78 if (verify_cc(ctx, reno))79 return 1;80 81 if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &cubic, sizeof(cubic)))82 return 1;83 if (verify_cc(ctx, cubic))84 return 1;85 86 return 0;87}88 89static __inline int bind_to_device(struct bpf_sock_addr *ctx)90{91 char veth1[IFNAMSIZ] = "test_sock_addr1";92 char veth2[IFNAMSIZ] = "test_sock_addr2";93 char missing[IFNAMSIZ] = "nonexistent_dev";94 char del_bind[IFNAMSIZ] = "";95 96 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,97 &veth1, sizeof(veth1)))98 return 1;99 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,100 &veth2, sizeof(veth2)))101 return 1;102 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,103 &missing, sizeof(missing)) != -ENODEV)104 return 1;105 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,106 &del_bind, sizeof(del_bind)))107 return 1;108 109 return 0;110}111 112static __inline int set_keepalive(struct bpf_sock_addr *ctx)113{114 int zero = 0, one = 1;115 116 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof(one)))117 return 1;118 if (ctx->type == SOCK_STREAM) {119 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPIDLE, &one, sizeof(one)))120 return 1;121 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPINTVL, &one, sizeof(one)))122 return 1;123 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPCNT, &one, sizeof(one)))124 return 1;125 if (bpf_setsockopt(ctx, SOL_TCP, TCP_SYNCNT, &one, sizeof(one)))126 return 1;127 if (bpf_setsockopt(ctx, SOL_TCP, TCP_USER_TIMEOUT, &one, sizeof(one)))128 return 1;129 }130 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_KEEPALIVE, &zero, sizeof(zero)))131 return 1;132 133 return 0;134}135 136static __inline int set_notsent_lowat(struct bpf_sock_addr *ctx)137{138 int lowat = 65535;139 140 if (ctx->type == SOCK_STREAM) {141 if (bpf_setsockopt(ctx, SOL_TCP, TCP_NOTSENT_LOWAT, &lowat, sizeof(lowat)))142 return 1;143 }144 145 return 0;146}147 148SEC("cgroup/connect4")149int connect_v4_prog(struct bpf_sock_addr *ctx)150{151 struct bpf_sock_tuple tuple = {};152 struct bpf_sock *sk;153 154 /* Verify that new destination is available. */155 memset(&tuple.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr));156 memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport));157 158 tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4);159 tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4);160 161 /* Bind to device and unbind it. */162 if (bind_to_device(ctx))163 return 0;164 165 if (set_keepalive(ctx))166 return 0;167 168 if (set_notsent_lowat(ctx))169 return 0;170 171 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)172 return 0;173 else if (ctx->type == SOCK_STREAM)174 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv4),175 BPF_F_CURRENT_NETNS, 0);176 else177 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv4),178 BPF_F_CURRENT_NETNS, 0);179 180 if (!sk)181 return 0;182 183 if (sk->src_ip4 != tuple.ipv4.daddr ||184 sk->src_port != DST_REWRITE_PORT4) {185 bpf_sk_release(sk);186 return 0;187 }188 189 bpf_sk_release(sk);190 191 /* Rewrite congestion control. */192 if (ctx->type == SOCK_STREAM && set_cc(ctx))193 return 0;194 195 /* Rewrite destination. */196 ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);197 ctx->user_port = bpf_htons(DST_REWRITE_PORT4);198 199 return do_bind(ctx) ? 1 : 0;200}201 202SEC("cgroup/connect4")203int connect_v4_deny_prog(struct bpf_sock_addr *ctx)204{205 return 0;206}207 208char _license[] SEC("license") = "GPL";209