1bd4aed0eSJiong Wang // SPDX-License-Identifier: GPL-2.0 2bd4aed0eSJiong Wang // Copyright (c) 2018 Facebook 3bd4aed0eSJiong Wang 4bd4aed0eSJiong Wang #include <linux/stddef.h> 5bd4aed0eSJiong Wang #include <linux/bpf.h> 6bd4aed0eSJiong Wang #include <sys/socket.h> 7bd4aed0eSJiong Wang 8bd4aed0eSJiong Wang #include "bpf_helpers.h" 9bd4aed0eSJiong Wang #include "bpf_endian.h" 10bd4aed0eSJiong Wang 11bd4aed0eSJiong Wang #define SRC_REWRITE_IP6_0 0 12bd4aed0eSJiong Wang #define SRC_REWRITE_IP6_1 0 13bd4aed0eSJiong Wang #define SRC_REWRITE_IP6_2 0 14bd4aed0eSJiong Wang #define SRC_REWRITE_IP6_3 6 15bd4aed0eSJiong Wang 16bd4aed0eSJiong Wang #define DST_REWRITE_IP6_0 0 17bd4aed0eSJiong Wang #define DST_REWRITE_IP6_1 0 18bd4aed0eSJiong Wang #define DST_REWRITE_IP6_2 0 19bd4aed0eSJiong Wang #define DST_REWRITE_IP6_3 1 20bd4aed0eSJiong Wang 21bd4aed0eSJiong Wang #define DST_REWRITE_PORT6 6666 22bd4aed0eSJiong Wang 23bd4aed0eSJiong Wang int _version SEC("version") = 1; 24bd4aed0eSJiong Wang 25bd4aed0eSJiong Wang SEC("cgroup/sendmsg6") 26bd4aed0eSJiong Wang int sendmsg_v6_prog(struct bpf_sock_addr *ctx) 27bd4aed0eSJiong Wang { 28bd4aed0eSJiong Wang if (ctx->type != SOCK_DGRAM) 29bd4aed0eSJiong Wang return 0; 30bd4aed0eSJiong Wang 31bd4aed0eSJiong Wang /* Rewrite source. */ 32bd4aed0eSJiong Wang if (ctx->msg_src_ip6[3] == bpf_htonl(1) || 33bd4aed0eSJiong Wang ctx->msg_src_ip6[3] == bpf_htonl(0)) { 34bd4aed0eSJiong Wang ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0); 35bd4aed0eSJiong Wang ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1); 36bd4aed0eSJiong Wang ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2); 37bd4aed0eSJiong Wang ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3); 38bd4aed0eSJiong Wang } else { 39bd4aed0eSJiong Wang /* Unexpected source. Reject sendmsg. */ 40bd4aed0eSJiong Wang return 0; 41bd4aed0eSJiong Wang } 42bd4aed0eSJiong Wang 43bd4aed0eSJiong Wang /* Rewrite destination. */ 44c8eee413SIlya Leoshkevich if (ctx->user_ip6[0] == bpf_htonl(0xFACEB00C)) { 45bd4aed0eSJiong Wang ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0); 46bd4aed0eSJiong Wang ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1); 47bd4aed0eSJiong Wang ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); 48bd4aed0eSJiong Wang ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3); 49bd4aed0eSJiong Wang 50bd4aed0eSJiong Wang ctx->user_port = bpf_htons(DST_REWRITE_PORT6); 51bd4aed0eSJiong Wang } else { 52bd4aed0eSJiong Wang /* Unexpected destination. Reject sendmsg. */ 53bd4aed0eSJiong Wang return 0; 54bd4aed0eSJiong Wang } 55bd4aed0eSJiong Wang 56bd4aed0eSJiong Wang return 1; 57bd4aed0eSJiong Wang } 58bd4aed0eSJiong Wang 59bd4aed0eSJiong Wang char _license[] SEC("license") = "GPL"; 60