160 lines
3.9 KiB
C
160 lines
3.9 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 SERV4_IP 0xc0a801feU /* 192.168.1.254 */
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#define SERV4_PORT 4040
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#define SERV4_REWRITE_IP 0x7f000001U /* 127.0.0.1 */
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#define SERV4_REWRITE_PORT 4444
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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/bind4")
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int bind_v4_prog(struct bpf_sock_addr *ctx)
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{
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struct bpf_sock *sk;
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__u32 user_ip4;
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__u16 user_port;
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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_INET)
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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_ip4 != bpf_htonl(SERV4_IP) ||
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ctx->user_port != bpf_htons(SERV4_PORT))
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return 0;
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// u8 narrow loads:
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user_ip4 = 0;
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user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[0] << 0;
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user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[1] << 8;
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user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[2] << 16;
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user_ip4 |= ((volatile __u8 *)&ctx->user_ip4)[3] << 24;
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if (ctx->user_ip4 != user_ip4)
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return 0;
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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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user_ip4 = 0;
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user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[0] << 0;
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user_ip4 |= ((volatile __u16 *)&ctx->user_ip4)[1] << 16;
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if (ctx->user_ip4 != user_ip4)
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return 0;
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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_ip4 = bpf_htonl(SERV4_REWRITE_IP);
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ctx->user_port = bpf_htons(SERV4_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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