// SPDX-License-Identifier: GPL-2.0 // Copyright (c) 2018 Facebook #include <linux/stddef.h> #include <linux/bpf.h> #include <sys/socket.h> #include "bpf_helpers.h" #include "bpf_endian.h" #define SRC_REWRITE_IP6_0 0 #define SRC_REWRITE_IP6_1 0 #define SRC_REWRITE_IP6_2 0 #define SRC_REWRITE_IP6_3 6 #define DST_REWRITE_IP6_0 0 #define DST_REWRITE_IP6_1 0 #define DST_REWRITE_IP6_2 0 #define DST_REWRITE_IP6_3 1 #define DST_REWRITE_PORT6 6666 int _version SEC("version") = 1; SEC("cgroup/sendmsg6") int sendmsg_v6_prog(struct bpf_sock_addr *ctx) { if (ctx->type != SOCK_DGRAM) return 0; /* Rewrite source. */ if (ctx->msg_src_ip6[3] == bpf_htonl(1) || ctx->msg_src_ip6[3] == bpf_htonl(0)) { ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0); ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1); ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2); ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3); } else { /* Unexpected source. Reject sendmsg. */ return 0; } /* Rewrite destination. */ if ((ctx->user_ip6[0] & 0xFFFF) == bpf_htons(0xFACE) && ctx->user_ip6[0] >> 16 == bpf_htons(0xB00C)) { ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0); ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1); ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3); ctx->user_port = bpf_htons(DST_REWRITE_PORT6); } else { /* Unexpected destination. Reject sendmsg. */ return 0; } return 1; } char _license[] SEC("license") = "GPL";