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 <linux/if.h> 10 #include <errno.h> 11 12 #include <bpf/bpf_helpers.h> 13 #include <bpf/bpf_endian.h> 14 15 #define SERV4_IP 0xc0a801feU /* 192.168.1.254 */ 16 #define SERV4_PORT 4040 17 #define SERV4_REWRITE_IP 0x7f000001U /* 127.0.0.1 */ 18 #define SERV4_REWRITE_PORT 4444 19 20 #ifndef IFNAMSIZ 21 #define IFNAMSIZ 16 22 #endif 23 24 static __inline int bind_to_device(struct bpf_sock_addr *ctx) 25 { 26 char veth1[IFNAMSIZ] = "test_sock_addr1"; 27 char veth2[IFNAMSIZ] = "test_sock_addr2"; 28 char missing[IFNAMSIZ] = "nonexistent_dev"; 29 char del_bind[IFNAMSIZ] = ""; 30 int veth1_idx, veth2_idx; 31 32 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 33 &veth1, sizeof(veth1))) 34 return 1; 35 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX, 36 &veth1_idx, sizeof(veth1_idx)) || !veth1_idx) 37 return 1; 38 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 39 &veth2, sizeof(veth2))) 40 return 1; 41 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX, 42 &veth2_idx, sizeof(veth2_idx)) || !veth2_idx || 43 veth1_idx == veth2_idx) 44 return 1; 45 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 46 &missing, sizeof(missing)) != -ENODEV) 47 return 1; 48 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX, 49 &veth1_idx, sizeof(veth1_idx))) 50 return 1; 51 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE, 52 &del_bind, sizeof(del_bind))) 53 return 1; 54 55 return 0; 56 } 57 58 static __inline int bind_reuseport(struct bpf_sock_addr *ctx) 59 { 60 int val = 1; 61 62 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 63 &val, sizeof(val))) 64 return 1; 65 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 66 &val, sizeof(val)) || !val) 67 return 1; 68 val = 0; 69 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 70 &val, sizeof(val))) 71 return 1; 72 if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT, 73 &val, sizeof(val)) || val) 74 return 1; 75 76 return 0; 77 } 78 79 static __inline int misc_opts(struct bpf_sock_addr *ctx, int opt) 80 { 81 int old, tmp, new = 0xeb9f; 82 83 /* Socket in test case has guarantee that old never equals to new. */ 84 if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)) || 85 old == new) 86 return 1; 87 if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &new, sizeof(new))) 88 return 1; 89 if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &tmp, sizeof(tmp)) || 90 tmp != new) 91 return 1; 92 if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old))) 93 return 1; 94 95 return 0; 96 } 97 98 SEC("cgroup/bind4") 99 int bind_v4_prog(struct bpf_sock_addr *ctx) 100 { 101 struct bpf_sock *sk; 102 __u32 user_ip4; 103 __u16 user_port; 104 105 sk = ctx->sk; 106 if (!sk) 107 return 0; 108 109 if (sk->family != AF_INET) 110 return 0; 111 112 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM) 113 return 0; 114 115 if (ctx->user_ip4 != bpf_htonl(SERV4_IP) || 116 ctx->user_port != bpf_htons(SERV4_PORT)) 117 return 0; 118 119 // u8 narrow loads: 120 user_ip4 = 0; 121 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[0] << 0; 122 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[1] << 8; 123 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[2] << 16; 124 user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[3] << 24; 125 if (ctx->user_ip4 != user_ip4) 126 return 0; 127 128 user_port = 0; 129 user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0; 130 user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8; 131 if (ctx->user_port != user_port) 132 return 0; 133 134 // u16 narrow loads: 135 user_ip4 = 0; 136 user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[0] << 0; 137 user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[1] << 16; 138 if (ctx->user_ip4 != user_ip4) 139 return 0; 140 141 /* Bind to device and unbind it. */ 142 if (bind_to_device(ctx)) 143 return 0; 144 145 /* Test for misc socket options. */ 146 if (misc_opts(ctx, SO_MARK) || misc_opts(ctx, SO_PRIORITY)) 147 return 0; 148 149 /* Set reuseport and unset */ 150 if (bind_reuseport(ctx)) 151 return 0; 152 153 ctx->user_ip4 = bpf_htonl(SERV4_REWRITE_IP); 154 ctx->user_port = bpf_htons(SERV4_REWRITE_PORT); 155 156 return 1; 157 } 158 159 char _license[] SEC("license") = "GPL"; 160