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 misc_opts(struct bpf_sock_addr *ctx, int opt) 61 { 62 int old, tmp, new = 0xeb9f; 63 64 /* Socket in test case has guarantee that old never equals to new. */ 65 if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)) || 66 old == new) 67 return 1; 68 if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &new, sizeof(new))) 69 return 1; 70 if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &tmp, sizeof(tmp)) || 71 tmp != new) 72 return 1; 73 if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old))) 74 return 1; 75 76 return 0; 77 } 78 79 SEC("cgroup/bind4") 80 int bind_v4_prog(struct bpf_sock_addr *ctx) 81 { 82 struct bpf_sock *sk; 83 __u32 user_ip4; 84 __u16 user_port; 85 86 sk = ctx->sk; 87 if (!sk) 88 return 0; 89 90 if (sk->family != AF_INET) 91 return 0; 92 93 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM) 94 return 0; 95 96 if (ctx->user_ip4 != bpf_htonl(SERV4_IP) || 97 ctx->user_port != bpf_htons(SERV4_PORT)) 98 return 0; 99 100 // u8 narrow loads: 101 user_ip4 = 0; 102 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[0] << 0; 103 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[1] << 8; 104 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[2] << 16; 105 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[3] << 24; 106 if (ctx->user_ip4 != user_ip4) 107 return 0; 108 109 user_port = 0; 110 user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0; 111 user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8; 112 if (ctx->user_port != user_port) 113 return 0; 114 115 // u16 narrow loads: 116 user_ip4 = 0; 117 user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[0] << 0; 118 user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[1] << 16; 119 if (ctx->user_ip4 != user_ip4) 120 return 0; 121 122 /* Bind to device and unbind it. */ 123 if (bind_to_device(ctx)) 124 return 0; 125 126 /* Test for misc socket options. */ 127 if (misc_opts(ctx, SO_MARK) || misc_opts(ctx, SO_PRIORITY)) 128 return 0; 129 130 ctx->user_ip4 = bpf_htonl(SERV4_REWRITE_IP); 131 ctx->user_port = bpf_htons(SERV4_REWRITE_PORT); 132 133 return 1; 134 } 135 136 char _license[] SEC("license") = "GPL"; 137