472 lines · c
1// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause2/* Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */3 4#include <stdnoreturn.h>5#include <stdlib.h>6#include <stdio.h>7#include <string.h>8#include <errno.h>9#include <unistd.h>10#include <getopt.h>11#include <signal.h>12#include <sys/types.h>13#include <bpf/bpf.h>14#include <bpf/libbpf.h>15#include <net/if.h>16#include <linux/if_link.h>17#include <linux/limits.h>18 19static unsigned int ifindex;20static __u32 attached_prog_id;21static bool attached_tc;22 23static void noreturn cleanup(int sig)24{25 LIBBPF_OPTS(bpf_xdp_attach_opts, opts);26 int prog_fd;27 int err;28 29 if (attached_prog_id == 0)30 exit(0);31 32 if (attached_tc) {33 LIBBPF_OPTS(bpf_tc_hook, hook,34 .ifindex = ifindex,35 .attach_point = BPF_TC_INGRESS);36 37 err = bpf_tc_hook_destroy(&hook);38 if (err < 0) {39 fprintf(stderr, "Error: bpf_tc_hook_destroy: %s\n", strerror(-err));40 fprintf(stderr, "Failed to destroy the TC hook\n");41 exit(1);42 }43 exit(0);44 }45 46 prog_fd = bpf_prog_get_fd_by_id(attached_prog_id);47 if (prog_fd < 0) {48 fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd));49 err = bpf_xdp_attach(ifindex, -1, 0, NULL);50 if (err < 0) {51 fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n", strerror(-err));52 fprintf(stderr, "Failed to detach XDP program\n");53 exit(1);54 }55 } else {56 opts.old_prog_fd = prog_fd;57 err = bpf_xdp_attach(ifindex, -1, XDP_FLAGS_REPLACE, &opts);58 close(prog_fd);59 if (err < 0) {60 fprintf(stderr, "Error: bpf_set_link_xdp_fd_opts: %s\n", strerror(-err));61 /* Not an error if already replaced by someone else. */62 if (err != -EEXIST) {63 fprintf(stderr, "Failed to detach XDP program\n");64 exit(1);65 }66 }67 }68 exit(0);69}70 71static noreturn void usage(const char *progname)72{73 fprintf(stderr, "Usage: %s [--iface <iface>|--prog <prog_id>] [--mss4 <mss ipv4> --mss6 <mss ipv6> --wscale <wscale> --ttl <ttl>] [--ports <port1>,<port2>,...] [--single] [--tc]\n",74 progname);75 exit(1);76}77 78static unsigned long parse_arg_ul(const char *progname, const char *arg, unsigned long limit)79{80 unsigned long res;81 char *endptr;82 83 errno = 0;84 res = strtoul(arg, &endptr, 10);85 if (errno != 0 || *endptr != '\0' || arg[0] == '\0' || res > limit)86 usage(progname);87 88 return res;89}90 91static void parse_options(int argc, char *argv[], unsigned int *ifindex, __u32 *prog_id,92 __u64 *tcpipopts, char **ports, bool *single, bool *tc)93{94 static struct option long_options[] = {95 { "help", no_argument, NULL, 'h' },96 { "iface", required_argument, NULL, 'i' },97 { "prog", required_argument, NULL, 'x' },98 { "mss4", required_argument, NULL, 4 },99 { "mss6", required_argument, NULL, 6 },100 { "wscale", required_argument, NULL, 'w' },101 { "ttl", required_argument, NULL, 't' },102 { "ports", required_argument, NULL, 'p' },103 { "single", no_argument, NULL, 's' },104 { "tc", no_argument, NULL, 'c' },105 { NULL, 0, NULL, 0 },106 };107 unsigned long mss4, wscale, ttl;108 unsigned long long mss6;109 unsigned int tcpipopts_mask = 0;110 111 if (argc < 2)112 usage(argv[0]);113 114 *ifindex = 0;115 *prog_id = 0;116 *tcpipopts = 0;117 *ports = NULL;118 *single = false;119 *tc = false;120 121 while (true) {122 int opt;123 124 opt = getopt_long(argc, argv, "", long_options, NULL);125 if (opt == -1)126 break;127 128 switch (opt) {129 case 'h':130 usage(argv[0]);131 break;132 case 'i':133 *ifindex = if_nametoindex(optarg);134 if (*ifindex == 0)135 usage(argv[0]);136 break;137 case 'x':138 *prog_id = parse_arg_ul(argv[0], optarg, UINT32_MAX);139 if (*prog_id == 0)140 usage(argv[0]);141 break;142 case 4:143 mss4 = parse_arg_ul(argv[0], optarg, UINT16_MAX);144 tcpipopts_mask |= 1 << 0;145 break;146 case 6:147 mss6 = parse_arg_ul(argv[0], optarg, UINT16_MAX);148 tcpipopts_mask |= 1 << 1;149 break;150 case 'w':151 wscale = parse_arg_ul(argv[0], optarg, 14);152 tcpipopts_mask |= 1 << 2;153 break;154 case 't':155 ttl = parse_arg_ul(argv[0], optarg, UINT8_MAX);156 tcpipopts_mask |= 1 << 3;157 break;158 case 'p':159 *ports = optarg;160 break;161 case 's':162 *single = true;163 break;164 case 'c':165 *tc = true;166 break;167 default:168 usage(argv[0]);169 }170 }171 if (optind < argc)172 usage(argv[0]);173 174 if (tcpipopts_mask == 0xf) {175 if (mss4 == 0 || mss6 == 0 || wscale == 0 || ttl == 0)176 usage(argv[0]);177 *tcpipopts = (mss6 << 32) | (ttl << 24) | (wscale << 16) | mss4;178 } else if (tcpipopts_mask != 0) {179 usage(argv[0]);180 }181 182 if (*ifindex != 0 && *prog_id != 0)183 usage(argv[0]);184 if (*ifindex == 0 && *prog_id == 0)185 usage(argv[0]);186}187 188static int syncookie_attach(const char *argv0, unsigned int ifindex, bool tc)189{190 struct bpf_prog_info info = {};191 __u32 info_len = sizeof(info);192 char xdp_filename[PATH_MAX];193 struct bpf_program *prog;194 struct bpf_object *obj;195 int prog_fd;196 int err;197 198 snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.bpf.o", argv0);199 obj = bpf_object__open_file(xdp_filename, NULL);200 err = libbpf_get_error(obj);201 if (err < 0) {202 fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));203 return err;204 }205 206 err = bpf_object__load(obj);207 if (err < 0) {208 fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));209 return err;210 }211 212 prog = bpf_object__find_program_by_name(obj, tc ? "syncookie_tc" : "syncookie_xdp");213 if (!prog) {214 fprintf(stderr, "Error: bpf_object__find_program_by_name: program was not found\n");215 return -ENOENT;216 }217 218 prog_fd = bpf_program__fd(prog);219 220 err = bpf_prog_get_info_by_fd(prog_fd, &info, &info_len);221 if (err < 0) {222 fprintf(stderr, "Error: bpf_prog_get_info_by_fd: %s\n",223 strerror(-err));224 goto out;225 }226 attached_tc = tc;227 attached_prog_id = info.id;228 signal(SIGINT, cleanup);229 signal(SIGTERM, cleanup);230 if (tc) {231 LIBBPF_OPTS(bpf_tc_hook, hook,232 .ifindex = ifindex,233 .attach_point = BPF_TC_INGRESS);234 LIBBPF_OPTS(bpf_tc_opts, opts,235 .handle = 1,236 .priority = 1,237 .prog_fd = prog_fd);238 239 err = bpf_tc_hook_create(&hook);240 if (err < 0) {241 fprintf(stderr, "Error: bpf_tc_hook_create: %s\n",242 strerror(-err));243 goto fail;244 }245 err = bpf_tc_attach(&hook, &opts);246 if (err < 0) {247 fprintf(stderr, "Error: bpf_tc_attach: %s\n",248 strerror(-err));249 goto fail;250 }251 252 } else {253 err = bpf_xdp_attach(ifindex, prog_fd,254 XDP_FLAGS_UPDATE_IF_NOEXIST, NULL);255 if (err < 0) {256 fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n",257 strerror(-err));258 goto fail;259 }260 }261 err = 0;262out:263 bpf_object__close(obj);264 return err;265fail:266 signal(SIGINT, SIG_DFL);267 signal(SIGTERM, SIG_DFL);268 attached_prog_id = 0;269 goto out;270}271 272static int syncookie_open_bpf_maps(__u32 prog_id, int *values_map_fd, int *ports_map_fd)273{274 struct bpf_prog_info prog_info;275 __u32 map_ids[8];276 __u32 info_len;277 int prog_fd;278 int err;279 int i;280 281 *values_map_fd = -1;282 *ports_map_fd = -1;283 284 prog_fd = bpf_prog_get_fd_by_id(prog_id);285 if (prog_fd < 0) {286 fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd));287 return prog_fd;288 }289 290 prog_info = (struct bpf_prog_info) {291 .nr_map_ids = 8,292 .map_ids = (__u64)(unsigned long)map_ids,293 };294 info_len = sizeof(prog_info);295 296 err = bpf_prog_get_info_by_fd(prog_fd, &prog_info, &info_len);297 if (err != 0) {298 fprintf(stderr, "Error: bpf_prog_get_info_by_fd: %s\n",299 strerror(-err));300 goto out;301 }302 303 if (prog_info.nr_map_ids < 2) {304 fprintf(stderr, "Error: Found %u BPF maps, expected at least 2\n",305 prog_info.nr_map_ids);306 err = -ENOENT;307 goto out;308 }309 310 for (i = 0; i < prog_info.nr_map_ids; i++) {311 struct bpf_map_info map_info = {};312 int map_fd;313 314 err = bpf_map_get_fd_by_id(map_ids[i]);315 if (err < 0) {316 fprintf(stderr, "Error: bpf_map_get_fd_by_id: %s\n", strerror(-err));317 goto err_close_map_fds;318 }319 map_fd = err;320 321 info_len = sizeof(map_info);322 err = bpf_map_get_info_by_fd(map_fd, &map_info, &info_len);323 if (err != 0) {324 fprintf(stderr, "Error: bpf_map_get_info_by_fd: %s\n",325 strerror(-err));326 close(map_fd);327 goto err_close_map_fds;328 }329 if (strcmp(map_info.name, "values") == 0) {330 *values_map_fd = map_fd;331 continue;332 }333 if (strcmp(map_info.name, "allowed_ports") == 0) {334 *ports_map_fd = map_fd;335 continue;336 }337 close(map_fd);338 }339 340 if (*values_map_fd != -1 && *ports_map_fd != -1) {341 err = 0;342 goto out;343 }344 345 err = -ENOENT;346 347err_close_map_fds:348 if (*values_map_fd != -1)349 close(*values_map_fd);350 if (*ports_map_fd != -1)351 close(*ports_map_fd);352 *values_map_fd = -1;353 *ports_map_fd = -1;354 355out:356 close(prog_fd);357 return err;358}359 360int main(int argc, char *argv[])361{362 int values_map_fd, ports_map_fd;363 __u64 tcpipopts;364 bool firstiter;365 __u64 prevcnt;366 __u32 prog_id;367 char *ports;368 bool single;369 int err = 0;370 bool tc;371 372 parse_options(argc, argv, &ifindex, &prog_id, &tcpipopts, &ports,373 &single, &tc);374 375 if (prog_id == 0) {376 if (!tc) {377 err = bpf_xdp_query_id(ifindex, 0, &prog_id);378 if (err < 0) {379 fprintf(stderr, "Error: bpf_get_link_xdp_id: %s\n",380 strerror(-err));381 goto out;382 }383 }384 if (prog_id == 0) {385 err = syncookie_attach(argv[0], ifindex, tc);386 if (err < 0)387 goto out;388 prog_id = attached_prog_id;389 }390 }391 392 err = syncookie_open_bpf_maps(prog_id, &values_map_fd, &ports_map_fd);393 if (err < 0)394 goto out;395 396 if (ports) {397 __u16 port_last = 0;398 __u32 port_idx = 0;399 char *p = ports;400 401 fprintf(stderr, "Replacing allowed ports\n");402 403 while (p && *p != '\0') {404 char *token = strsep(&p, ",");405 __u16 port;406 407 port = parse_arg_ul(argv[0], token, UINT16_MAX);408 err = bpf_map_update_elem(ports_map_fd, &port_idx, &port, BPF_ANY);409 if (err != 0) {410 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));411 fprintf(stderr, "Failed to add port %u (index %u)\n",412 port, port_idx);413 goto out_close_maps;414 }415 fprintf(stderr, "Added port %u\n", port);416 port_idx++;417 }418 err = bpf_map_update_elem(ports_map_fd, &port_idx, &port_last, BPF_ANY);419 if (err != 0) {420 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));421 fprintf(stderr, "Failed to add the terminator value 0 (index %u)\n",422 port_idx);423 goto out_close_maps;424 }425 }426 427 if (tcpipopts) {428 __u32 key = 0;429 430 fprintf(stderr, "Replacing TCP/IP options\n");431 432 err = bpf_map_update_elem(values_map_fd, &key, &tcpipopts, BPF_ANY);433 if (err != 0) {434 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));435 goto out_close_maps;436 }437 }438 439 if ((ports || tcpipopts) && attached_prog_id == 0 && !single)440 goto out_close_maps;441 442 prevcnt = 0;443 firstiter = true;444 while (true) {445 __u32 key = 1;446 __u64 value;447 448 err = bpf_map_lookup_elem(values_map_fd, &key, &value);449 if (err != 0) {450 fprintf(stderr, "Error: bpf_map_lookup_elem: %s\n", strerror(-err));451 goto out_close_maps;452 }453 if (firstiter) {454 prevcnt = value;455 firstiter = false;456 }457 if (single) {458 printf("Total SYNACKs generated: %llu\n", value);459 break;460 }461 printf("SYNACKs generated: %llu (total %llu)\n", value - prevcnt, value);462 prevcnt = value;463 sleep(1);464 }465 466out_close_maps:467 close(values_map_fd);468 close(ports_map_fd);469out:470 return err == 0 ? 0 : 1;471}472