1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2018 Facebook 3 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 <sys/socket.h> 11 #include <netinet/tcp.h> 12 #include <linux/if.h> 13 #include <errno.h> 14 15 #include <bpf/bpf_helpers.h> 16 #include <bpf/bpf_endian.h> 17 18 #define SRC_REWRITE_IP4 0x7f000004U 19 #define DST_REWRITE_IP4 0x7f000001U 20 #define DST_REWRITE_PORT4 4444 21 22 #ifndef TCP_CA_NAME_MAX 23 #define TCP_CA_NAME_MAX 16 24 #endif 25 26 #ifndef TCP_NOTSENT_LOWAT 27 #define TCP_NOTSENT_LOWAT 25 28 #endif 29 30 #ifndef IFNAMSIZ 31 #define IFNAMSIZ 16 32 #endif 33 34 __attribute__ ((noinline)) 35 int do_bind(struct bpf_sock_addr *ctx) 36 { 37 struct sockaddr_in sa = {}; 38 39 sa.sin_family = AF_INET; 40 sa.sin_port = bpf_htons(0); 41 sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4); 42 43 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0) 44 return 0; 45 46 return 1; 47 } 48 49 static __inline int verify_cc(struct bpf_sock_addr *ctx, 50 char expected[TCP_CA_NAME_MAX]) 51 { 52 char buf[TCP_CA_NAME_MAX]; 53 int i; 54 55 if (bpf_getsockopt(ctx, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf))) 56 return 1; 57 58 for (i = 0; i < TCP_CA_NAME_MAX; i++) { 59 if (buf[i] != expected[i]) 60 return 1; 61 if (buf[i] == 0) 62 break; 63 } 64 65 return 0; 66 } 67 68 static __inline int set_cc(struct bpf_sock_addr *ctx) 69 { 70 char reno[TCP_CA_NAME_MAX] = "reno"; 71 char cubic[TCP_CA_NAME_MAX] = "cubic"; 72 73 if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &reno, sizeof(reno))) 74 return 1; 75 if (verify_cc(ctx, reno)) 76 return 1; 77 78 if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &cubic, sizeof(cubic))) 79 return 1; 80 if (verify_cc(ctx, cubic)) 81 return 1; 82 83 return 0; 84 } 85 86 static __inline int bind_to_device(struct bpf_sock_addr *ctx) 87 { 88 char veth1[IFNAMSIZ] = "test_sock_addr1"; 89 char veth2[IFNAMSIZ] = "test_sock_addr2"; 90 char missing[IFNAMSIZ] = "nonexistent_dev"; 91 char del_bind[IFNAMSIZ] = ""; 92 93 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 94 &veth1, sizeof(veth1))) 95 return 1; 96 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 97 &veth2, sizeof(veth2))) 98 return 1; 99 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 100 &missing, sizeof(missing)) != -ENODEV) 101 return 1; 102 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 103 &del_bind, sizeof(del_bind))) 104 return 1; 105 106 return 0; 107 } 108 109 static __inline int set_keepalive(struct bpf_sock_addr *ctx) 110 { 111 int zero = 0, one = 1; 112 113 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof(one))) 114 return 1; 115 if (ctx->type == SOCK_STREAM) { 116 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPIDLE, &one, sizeof(one))) 117 return 1; 118 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPINTVL, &one, sizeof(one))) 119 return 1; 120 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPCNT, &one, sizeof(one))) 121 return 1; 122 if (bpf_setsockopt(ctx, SOL_TCP, TCP_SYNCNT, &one, sizeof(one))) 123 return 1; 124 if (bpf_setsockopt(ctx, SOL_TCP, TCP_USER_TIMEOUT, &one, sizeof(one))) 125 return 1; 126 } 127 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_KEEPALIVE, &zero, sizeof(zero))) 128 return 1; 129 130 return 0; 131 } 132 133 static __inline int set_notsent_lowat(struct bpf_sock_addr *ctx) 134 { 135 int lowat = 65535; 136 137 if (ctx->type == SOCK_STREAM) { 138 if (bpf_setsockopt(ctx, SOL_TCP, TCP_NOTSENT_LOWAT, &lowat, sizeof(lowat))) 139 return 1; 140 } 141 142 return 0; 143 } 144 145 SEC("cgroup/connect4") 146 int connect_v4_prog(struct bpf_sock_addr *ctx) 147 { 148 struct bpf_sock_tuple tuple = {}; 149 struct bpf_sock *sk; 150 151 /* Verify that new destination is available. */ 152 memset(&tuple.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr)); 153 memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport)); 154 155 tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4); 156 tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4); 157 158 /* Bind to device and unbind it. */ 159 if (bind_to_device(ctx)) 160 return 0; 161 162 if (set_keepalive(ctx)) 163 return 0; 164 165 if (set_notsent_lowat(ctx)) 166 return 0; 167 168 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM) 169 return 0; 170 else if (ctx->type == SOCK_STREAM) 171 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv4), 172 BPF_F_CURRENT_NETNS, 0); 173 else 174 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv4), 175 BPF_F_CURRENT_NETNS, 0); 176 177 if (!sk) 178 return 0; 179 180 if (sk->src_ip4 != tuple.ipv4.daddr || 181 sk->src_port != DST_REWRITE_PORT4) { 182 bpf_sk_release(sk); 183 return 0; 184 } 185 186 bpf_sk_release(sk); 187 188 /* Rewrite congestion control. */ 189 if (ctx->type == SOCK_STREAM && set_cc(ctx)) 190 return 0; 191 192 /* Rewrite destination. */ 193 ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4); 194 ctx->user_port = bpf_htons(DST_REWRITE_PORT4); 195 196 return do_bind(ctx) ? 1 : 0; 197 } 198 199 char _license[] SEC("license") = "GPL"; 200