1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun // Copyright (c) 2018 Facebook 3*4882a593Smuzhiyun 4*4882a593Smuzhiyun #include <linux/stddef.h> 5*4882a593Smuzhiyun #include <linux/bpf.h> 6*4882a593Smuzhiyun #include <sys/socket.h> 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun #include <bpf/bpf_helpers.h> 9*4882a593Smuzhiyun #include <bpf/bpf_endian.h> 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun #define SRC_REWRITE_IP6_0 0 12*4882a593Smuzhiyun #define SRC_REWRITE_IP6_1 0 13*4882a593Smuzhiyun #define SRC_REWRITE_IP6_2 0 14*4882a593Smuzhiyun #define SRC_REWRITE_IP6_3 6 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun #define DST_REWRITE_IP6_0 0 17*4882a593Smuzhiyun #define DST_REWRITE_IP6_1 0 18*4882a593Smuzhiyun #define DST_REWRITE_IP6_2 0 19*4882a593Smuzhiyun #define DST_REWRITE_IP6_3 1 20*4882a593Smuzhiyun 21*4882a593Smuzhiyun #define DST_REWRITE_PORT6 6666 22*4882a593Smuzhiyun 23*4882a593Smuzhiyun int _version SEC("version") = 1; 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun SEC("cgroup/sendmsg6") sendmsg_v6_prog(struct bpf_sock_addr * ctx)26*4882a593Smuzhiyunint sendmsg_v6_prog(struct bpf_sock_addr *ctx) 27*4882a593Smuzhiyun { 28*4882a593Smuzhiyun if (ctx->type != SOCK_DGRAM) 29*4882a593Smuzhiyun return 0; 30*4882a593Smuzhiyun 31*4882a593Smuzhiyun /* Rewrite source. */ 32*4882a593Smuzhiyun if (ctx->msg_src_ip6[3] == bpf_htonl(1) || 33*4882a593Smuzhiyun ctx->msg_src_ip6[3] == bpf_htonl(0)) { 34*4882a593Smuzhiyun ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0); 35*4882a593Smuzhiyun ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1); 36*4882a593Smuzhiyun ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2); 37*4882a593Smuzhiyun ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3); 38*4882a593Smuzhiyun } else { 39*4882a593Smuzhiyun /* Unexpected source. Reject sendmsg. */ 40*4882a593Smuzhiyun return 0; 41*4882a593Smuzhiyun } 42*4882a593Smuzhiyun 43*4882a593Smuzhiyun /* Rewrite destination. */ 44*4882a593Smuzhiyun if (ctx->user_ip6[0] == bpf_htonl(0xFACEB00C)) { 45*4882a593Smuzhiyun ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0); 46*4882a593Smuzhiyun ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1); 47*4882a593Smuzhiyun ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2); 48*4882a593Smuzhiyun ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3); 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun ctx->user_port = bpf_htons(DST_REWRITE_PORT6); 51*4882a593Smuzhiyun } else { 52*4882a593Smuzhiyun /* Unexpected destination. Reject sendmsg. */ 53*4882a593Smuzhiyun return 0; 54*4882a593Smuzhiyun } 55*4882a593Smuzhiyun 56*4882a593Smuzhiyun return 1; 57*4882a593Smuzhiyun } 58*4882a593Smuzhiyun 59*4882a593Smuzhiyun char _license[] SEC("license") = "GPL"; 60