1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <string.h> 4 5 #include <linux/stddef.h> 6 #include <linux/bpf.h> 7 #include <linux/in.h> 8 #include <linux/in6.h> 9 #include <sys/socket.h> 10 #include <netinet/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 SERV4_IP 0xc0a801feU /* 192.168.1.254 */ 18 #define SERV4_PORT 4040 19 #define SERV4_REWRITE_IP 0x7f000001U /* 127.0.0.1 */ 20 #define SERV4_REWRITE_PORT 4444 21 22 #ifndef IFNAMSIZ 23 #define IFNAMSIZ 16 24 #endif 25 26 static __inline int bind_to_device(struct bpf_sock_addr *ctx) 27 { 28 char veth1[IFNAMSIZ] = "test_sock_addr1"; 29 char veth2[IFNAMSIZ] = "test_sock_addr2"; 30 char missing[IFNAMSIZ] = "nonexistent_dev"; 31 char del_bind[IFNAMSIZ] = ""; 32 int veth1_idx, veth2_idx; 33 34 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 35 &veth1, sizeof(veth1))) 36 return 1; 37 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX, 38 &veth1_idx, sizeof(veth1_idx)) || !veth1_idx) 39 return 1; 40 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 41 &veth2, sizeof(veth2))) 42 return 1; 43 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX, 44 &veth2_idx, sizeof(veth2_idx)) || !veth2_idx || 45 veth1_idx == veth2_idx) 46 return 1; 47 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 48 &missing, sizeof(missing)) != -ENODEV) 49 return 1; 50 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX, 51 &veth1_idx, sizeof(veth1_idx))) 52 return 1; 53 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 54 &del_bind, sizeof(del_bind))) 55 return 1; 56 57 return 0; 58 } 59 60 static __inline int bind_reuseport(struct bpf_sock_addr *ctx) 61 { 62 int val = 1; 63 64 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 65 &val, sizeof(val))) 66 return 1; 67 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 68 &val, sizeof(val)) || !val) 69 return 1; 70 val = 0; 71 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 72 &val, sizeof(val))) 73 return 1; 74 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 75 &val, sizeof(val)) || val) 76 return 1; 77 78 return 0; 79 } 80 81 static __inline int misc_opts(struct bpf_sock_addr *ctx, int opt) 82 { 83 int old, tmp, new = 0xeb9f; 84 85 /* Socket in test case has guarantee that old never equals to new. */ 86 if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)) || 87 old == new) 88 return 1; 89 if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &new, sizeof(new))) 90 return 1; 91 if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &tmp, sizeof(tmp)) || 92 tmp != new) 93 return 1; 94 if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old))) 95 return 1; 96 97 return 0; 98 } 99 100 SEC("cgroup/bind4") 101 int bind_v4_prog(struct bpf_sock_addr *ctx) 102 { 103 struct bpf_sock *sk; 104 __u32 user_ip4; 105 __u16 user_port; 106 107 sk = ctx->sk; 108 if (!sk) 109 return 0; 110 111 if (sk->family != AF_INET) 112 return 0; 113 114 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM) 115 return 0; 116 117 if (ctx->user_ip4 != bpf_htonl(SERV4_IP) || 118 ctx->user_port != bpf_htons(SERV4_PORT)) 119 return 0; 120 121 // u8 narrow loads: 122 user_ip4 = 0; 123 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[0] << 0; 124 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[1] << 8; 125 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[2] << 16; 126 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[3] << 24; 127 if (ctx->user_ip4 != user_ip4) 128 return 0; 129 130 user_port = 0; 131 user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0; 132 user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8; 133 if (ctx->user_port != user_port) 134 return 0; 135 136 // u16 narrow loads: 137 user_ip4 = 0; 138 user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[0] << 0; 139 user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[1] << 16; 140 if (ctx->user_ip4 != user_ip4) 141 return 0; 142 143 /* Bind to device and unbind it. */ 144 if (bind_to_device(ctx)) 145 return 0; 146 147 /* Test for misc socket options. */ 148 if (misc_opts(ctx, SO_MARK) || misc_opts(ctx, SO_PRIORITY)) 149 return 0; 150 151 /* Set reuseport and unset */ 152 if (bind_reuseport(ctx)) 153 return 0; 154 155 ctx->user_ip4 = bpf_htonl(SERV4_REWRITE_IP); 156 ctx->user_port = bpf_htons(SERV4_REWRITE_PORT); 157 158 return 1; 159 } 160 161 char _license[] SEC("license") = "GPL"; 162