bpf/progs/bind6_prog.c

0001 // SPDX-License-Identifier: GPL-2.0
0002
0003 #include <string.h>
0004
0005 #include <linux/stddef.h>
0006 #include <linux/bpf.h>
0007 #include <linux/in.h>
0008 #include <linux/in6.h>
0009 #include <sys/socket.h>
0010 #include <netinet/tcp.h>
0011 #include <linux/if.h>
0012 #include <errno.h>
0013
0014 #include <bpf/bpf_helpers.h>
0015 #include <bpf/bpf_endian.h>
0016
0017 #define SERV6_IP_0      0xfaceb00c /* face:b00c:1234:5678::abcd */
0018 #define SERV6_IP_1      0x12345678
0019 #define SERV6_IP_2      0x00000000
0020 #define SERV6_IP_3      0x0000abcd
0021 #define SERV6_PORT      6060
0022 #define SERV6_REWRITE_IP_0  0x00000000
0023 #define SERV6_REWRITE_IP_1  0x00000000
0024 #define SERV6_REWRITE_IP_2  0x00000000
0025 #define SERV6_REWRITE_IP_3  0x00000001
0026 #define SERV6_REWRITE_PORT  6666
0027
0028 #ifndef IFNAMSIZ
0029 #define IFNAMSIZ 16
0030 #endif
0031
0032 static __inline int bind_to_device(struct bpf_sock_addr *ctx)
0033 {
0034     char veth1[IFNAMSIZ] = "test_sock_addr1";
0035     char veth2[IFNAMSIZ] = "test_sock_addr2";
0036     char missing[IFNAMSIZ] = "nonexistent_dev";
0037     char del_bind[IFNAMSIZ] = "";
0038     int veth1_idx, veth2_idx;
0039
0040     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
0041                &veth1, sizeof(veth1)))
0042         return 1;
0043     if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
0044                &veth1_idx, sizeof(veth1_idx)) || !veth1_idx)
0045         return 1;
0046     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
0047                &veth2, sizeof(veth2)))
0048         return 1;
0049     if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
0050                &veth2_idx, sizeof(veth2_idx)) || !veth2_idx ||
0051         veth1_idx == veth2_idx)
0052         return 1;
0053     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
0054                &missing, sizeof(missing)) != -ENODEV)
0055         return 1;
0056     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
0057                &veth1_idx, sizeof(veth1_idx)))
0058         return 1;
0059     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
0060                &del_bind, sizeof(del_bind)))
0061         return 1;
0062
0063     return 0;
0064 }
0065
0066 static __inline int bind_reuseport(struct bpf_sock_addr *ctx)
0067 {
0068     int val = 1;
0069
0070     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
0071                &val, sizeof(val)))
0072         return 1;
0073     if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
0074                &val, sizeof(val)) || !val)
0075         return 1;
0076     val = 0;
0077     if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
0078                &val, sizeof(val)))
0079         return 1;
0080     if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
0081                &val, sizeof(val)) || val)
0082         return 1;
0083
0084     return 0;
0085 }
0086
0087 static __inline int misc_opts(struct bpf_sock_addr *ctx, int opt)
0088 {
0089     int old, tmp, new = 0xeb9f;
0090
0091     /* Socket in test case has guarantee that old never equals to new. */
0092     if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)) ||
0093         old == new)
0094         return 1;
0095     if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &new, sizeof(new)))
0096         return 1;
0097     if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &tmp, sizeof(tmp)) ||
0098         tmp != new)
0099         return 1;
0100     if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)))
0101         return 1;
0102
0103     return 0;
0104 }
0105
0106 SEC("cgroup/bind6")
0107 int bind_v6_prog(struct bpf_sock_addr *ctx)
0108 {
0109     struct bpf_sock *sk;
0110     __u32 user_ip6;
0111     __u16 user_port;
0112     int i;
0113
0114     sk = ctx->sk;
0115     if (!sk)
0116         return 0;
0117
0118     if (sk->family != AF_INET6)
0119         return 0;
0120
0121     if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
0122         return 0;
0123
0124     if (ctx->user_ip6[0] != bpf_htonl(SERV6_IP_0) ||
0125         ctx->user_ip6[1] != bpf_htonl(SERV6_IP_1) ||
0126         ctx->user_ip6[2] != bpf_htonl(SERV6_IP_2) ||
0127         ctx->user_ip6[3] != bpf_htonl(SERV6_IP_3) ||
0128         ctx->user_port != bpf_htons(SERV6_PORT))
0129         return 0;
0130
0131     // u8 narrow loads:
0132     for (i = 0; i < 4; i++) {
0133         user_ip6 = 0;
0134         user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[0] << 0;
0135         user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[1] << 8;
0136         user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[2] << 16;
0137         user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[3] << 24;
0138         if (ctx->user_ip6[i] != user_ip6)
0139             return 0;
0140     }
0141
0142     user_port = 0;
0143     user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0;
0144     user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8;
0145     if (ctx->user_port != user_port)
0146         return 0;
0147
0148     // u16 narrow loads:
0149     for (i = 0; i < 4; i++) {
0150         user_ip6 = 0;
0151         user_ip6 |= ((volatile __u16 *)&ctx->user_ip6[i])[0] << 0;
0152         user_ip6 |= ((volatile __u16 *)&ctx->user_ip6[i])[1] << 16;
0153         if (ctx->user_ip6[i] != user_ip6)
0154             return 0;
0155     }
0156
0157     /* Bind to device and unbind it. */
0158     if (bind_to_device(ctx))
0159         return 0;
0160
0161     /* Test for misc socket options. */
0162     if (misc_opts(ctx, SO_MARK) || misc_opts(ctx, SO_PRIORITY))
0163         return 0;
0164
0165     /* Set reuseport and unset */
0166     if (bind_reuseport(ctx))
0167         return 0;
0168
0169     ctx->user_ip6[0] = bpf_htonl(SERV6_REWRITE_IP_0);
0170     ctx->user_ip6[1] = bpf_htonl(SERV6_REWRITE_IP_1);
0171     ctx->user_ip6[2] = bpf_htonl(SERV6_REWRITE_IP_2);
0172     ctx->user_ip6[3] = bpf_htonl(SERV6_REWRITE_IP_3);
0173     ctx->user_port = bpf_htons(SERV6_REWRITE_PORT);
0174
0175     return 1;
0176 }
0177
0178 char _license[] SEC("license") = "GPL";