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 SERV6_IP_0		0xfaceb00c /* face:b00c:1234:5678::abcd */
 16#define SERV6_IP_1		0x12345678
 17#define SERV6_IP_2		0x00000000
 18#define SERV6_IP_3		0x0000abcd
 19#define SERV6_PORT		6060
 20#define SERV6_REWRITE_IP_0	0x00000000
 21#define SERV6_REWRITE_IP_1	0x00000000
 22#define SERV6_REWRITE_IP_2	0x00000000
 23#define SERV6_REWRITE_IP_3	0x00000001
 24#define SERV6_REWRITE_PORT	6666
 25
 26#ifndef IFNAMSIZ
 27#define IFNAMSIZ 16
 28#endif
 29
 30static __inline int bind_to_device(struct bpf_sock_addr *ctx)
 31{
 32	char veth1[IFNAMSIZ] = "test_sock_addr1";
 33	char veth2[IFNAMSIZ] = "test_sock_addr2";
 34	char missing[IFNAMSIZ] = "nonexistent_dev";
 35	char del_bind[IFNAMSIZ] = "";
 36	int veth1_idx, veth2_idx;
 37
 38	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
 39			   &veth1, sizeof(veth1)))
 40		return 1;
 41	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
 42			   &veth1_idx, sizeof(veth1_idx)) || !veth1_idx)
 43		return 1;
 44	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
 45			   &veth2, sizeof(veth2)))
 46		return 1;
 47	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
 48			   &veth2_idx, sizeof(veth2_idx)) || !veth2_idx ||
 49	    veth1_idx == veth2_idx)
 50		return 1;
 51	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
 52			   &missing, sizeof(missing)) != -ENODEV)
 53		return 1;
 54	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
 55			   &veth1_idx, sizeof(veth1_idx)))
 56		return 1;
 57	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
 58			   &del_bind, sizeof(del_bind)))
 59		return 1;
 60
 61	return 0;
 62}
 63
 64static __inline int bind_reuseport(struct bpf_sock_addr *ctx)
 65{
 66	int val = 1;
 67
 68	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
 69			   &val, sizeof(val)))
 70		return 1;
 71	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
 72			   &val, sizeof(val)) || !val)
 73		return 1;
 74	val = 0;
 75	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
 76			   &val, sizeof(val)))
 77		return 1;
 78	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
 79			   &val, sizeof(val)) || val)
 80		return 1;
 81
 82	return 0;
 83}
 84
 85static __inline int misc_opts(struct bpf_sock_addr *ctx, int opt)
 86{
 87	int old, tmp, new = 0xeb9f;
 88
 89	/* Socket in test case has guarantee that old never equals to new. */
 90	if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)) ||
 91	    old == new)
 92		return 1;
 93	if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &new, sizeof(new)))
 94		return 1;
 95	if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &tmp, sizeof(tmp)) ||
 96	    tmp != new)
 97		return 1;
 98	if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)))
 99		return 1;
100
101	return 0;
102}
103
104SEC("cgroup/bind6")
105int bind_v6_prog(struct bpf_sock_addr *ctx)
106{
107	struct bpf_sock *sk;
108	__u32 user_ip6;
109	__u16 user_port;
110	int i;
111
112	sk = ctx->sk;
113	if (!sk)
114		return 0;
115
116	if (sk->family != AF_INET6)
117		return 0;
118
119	if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
120		return 0;
121
122	if (ctx->user_ip6[0] != bpf_htonl(SERV6_IP_0) ||
123	    ctx->user_ip6[1] != bpf_htonl(SERV6_IP_1) ||
124	    ctx->user_ip6[2] != bpf_htonl(SERV6_IP_2) ||
125	    ctx->user_ip6[3] != bpf_htonl(SERV6_IP_3) ||
126	    ctx->user_port != bpf_htons(SERV6_PORT))
127		return 0;
128
129	// u8 narrow loads:
130	for (i = 0; i < 4; i++) {
131		user_ip6 = 0;
132		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[0] << 0;
133		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[1] << 8;
134		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[2] << 16;
135		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[3] << 24;
136		if (ctx->user_ip6[i] != user_ip6)
137			return 0;
138	}
139
140	user_port = 0;
141	user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0;
142	user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8;
143	if (ctx->user_port != user_port)
144		return 0;
145
146	// u16 narrow loads:
147	for (i = 0; i < 4; i++) {
148		user_ip6 = 0;
149		user_ip6 |= ((volatile __u16 *)&ctx->user_ip6[i])[0] << 0;
150		user_ip6 |= ((volatile __u16 *)&ctx->user_ip6[i])[1] << 16;
151		if (ctx->user_ip6[i] != user_ip6)
152			return 0;
153	}
154
155	/* Bind to device and unbind it. */
156	if (bind_to_device(ctx))
157		return 0;
158
159	/* Test for misc socket options. */
160	if (misc_opts(ctx, SO_MARK) || misc_opts(ctx, SO_PRIORITY))
161		return 0;
162
163	/* Set reuseport and unset */
164	if (bind_reuseport(ctx))
165		return 0;
166
167	ctx->user_ip6[0] = bpf_htonl(SERV6_REWRITE_IP_0);
168	ctx->user_ip6[1] = bpf_htonl(SERV6_REWRITE_IP_1);
169	ctx->user_ip6[2] = bpf_htonl(SERV6_REWRITE_IP_2);
170	ctx->user_ip6[3] = bpf_htonl(SERV6_REWRITE_IP_3);
171	ctx->user_port = bpf_htons(SERV6_REWRITE_PORT);
172
173	return 1;
174}
175
176char _license[] SEC("license") = "GPL";