177 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			177 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
// SPDX-License-Identifier: GPL-2.0
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#include <string.h>
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#include <linux/stddef.h>
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#include <linux/bpf.h>
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#include <linux/in.h>
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#include <linux/in6.h>
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#include <linux/if.h>
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#include <errno.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_endian.h>
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#define SERV6_IP_0		0xfaceb00c /* face:b00c:1234:5678::abcd */
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#define SERV6_IP_1		0x12345678
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#define SERV6_IP_2		0x00000000
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#define SERV6_IP_3		0x0000abcd
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#define SERV6_PORT		6060
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#define SERV6_REWRITE_IP_0	0x00000000
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#define SERV6_REWRITE_IP_1	0x00000000
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#define SERV6_REWRITE_IP_2	0x00000000
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#define SERV6_REWRITE_IP_3	0x00000001
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#define SERV6_REWRITE_PORT	6666
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#ifndef IFNAMSIZ
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#define IFNAMSIZ 16
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#endif
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static __inline int bind_to_device(struct bpf_sock_addr *ctx)
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{
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	char veth1[IFNAMSIZ] = "test_sock_addr1";
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	char veth2[IFNAMSIZ] = "test_sock_addr2";
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	char missing[IFNAMSIZ] = "nonexistent_dev";
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	char del_bind[IFNAMSIZ] = "";
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	int veth1_idx, veth2_idx;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
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			   &veth1, sizeof(veth1)))
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		return 1;
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	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
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			   &veth1_idx, sizeof(veth1_idx)) || !veth1_idx)
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		return 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
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			   &veth2, sizeof(veth2)))
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		return 1;
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	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
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			   &veth2_idx, sizeof(veth2_idx)) || !veth2_idx ||
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	    veth1_idx == veth2_idx)
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		return 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
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			   &missing, sizeof(missing)) != -ENODEV)
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		return 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTOIFINDEX,
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			   &veth1_idx, sizeof(veth1_idx)))
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		return 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
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			   &del_bind, sizeof(del_bind)))
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		return 1;
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	return 0;
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}
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static __inline int bind_reuseport(struct bpf_sock_addr *ctx)
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{
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	int val = 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
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			   &val, sizeof(val)))
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		return 1;
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	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
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			   &val, sizeof(val)) || !val)
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		return 1;
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	val = 0;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
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			   &val, sizeof(val)))
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		return 1;
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	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_REUSEPORT,
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			   &val, sizeof(val)) || val)
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		return 1;
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	return 0;
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}
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static __inline int misc_opts(struct bpf_sock_addr *ctx, int opt)
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{
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	int old, tmp, new = 0xeb9f;
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	/* Socket in test case has guarantee that old never equals to new. */
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	if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)) ||
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	    old == new)
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		return 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &new, sizeof(new)))
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		return 1;
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	if (bpf_getsockopt(ctx, SOL_SOCKET, opt, &tmp, sizeof(tmp)) ||
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	    tmp != new)
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		return 1;
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	if (bpf_setsockopt(ctx, SOL_SOCKET, opt, &old, sizeof(old)))
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		return 1;
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	return 0;
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}
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SEC("cgroup/bind6")
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int bind_v6_prog(struct bpf_sock_addr *ctx)
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{
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	struct bpf_sock *sk;
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	__u32 user_ip6;
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	__u16 user_port;
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	int i;
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	sk = ctx->sk;
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	if (!sk)
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		return 0;
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	if (sk->family != AF_INET6)
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		return 0;
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	if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
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		return 0;
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	if (ctx->user_ip6[0] != bpf_htonl(SERV6_IP_0) ||
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	    ctx->user_ip6[1] != bpf_htonl(SERV6_IP_1) ||
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	    ctx->user_ip6[2] != bpf_htonl(SERV6_IP_2) ||
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	    ctx->user_ip6[3] != bpf_htonl(SERV6_IP_3) ||
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	    ctx->user_port != bpf_htons(SERV6_PORT))
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		return 0;
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	// u8 narrow loads:
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	for (i = 0; i < 4; i++) {
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		user_ip6 = 0;
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		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[0] << 0;
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		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[1] << 8;
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		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[2] << 16;
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		user_ip6 |= ((volatile __u8 *)&ctx->user_ip6[i])[3] << 24;
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		if (ctx->user_ip6[i] != user_ip6)
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			return 0;
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	}
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	user_port = 0;
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	user_port |= ((volatile __u8 *)&ctx->user_port)[0] << 0;
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	user_port |= ((volatile __u8 *)&ctx->user_port)[1] << 8;
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	if (ctx->user_port != user_port)
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		return 0;
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	// u16 narrow loads:
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	for (i = 0; i < 4; i++) {
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		user_ip6 = 0;
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		user_ip6 |= ((volatile __u16 *)&ctx->user_ip6[i])[0] << 0;
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		user_ip6 |= ((volatile __u16 *)&ctx->user_ip6[i])[1] << 16;
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		if (ctx->user_ip6[i] != user_ip6)
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			return 0;
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	}
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	/* Bind to device and unbind it. */
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	if (bind_to_device(ctx))
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		return 0;
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	/* Test for misc socket options. */
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	if (misc_opts(ctx, SO_MARK) || misc_opts(ctx, SO_PRIORITY))
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		return 0;
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	/* Set reuseport and unset */
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	if (bind_reuseport(ctx))
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		return 0;
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	ctx->user_ip6[0] = bpf_htonl(SERV6_REWRITE_IP_0);
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	ctx->user_ip6[1] = bpf_htonl(SERV6_REWRITE_IP_1);
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	ctx->user_ip6[2] = bpf_htonl(SERV6_REWRITE_IP_2);
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	ctx->user_ip6[3] = bpf_htonl(SERV6_REWRITE_IP_3);
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	ctx->user_port = bpf_htons(SERV6_REWRITE_PORT);
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	return 1;
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}
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char _license[] SEC("license") = "GPL";
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