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1// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
2/* 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}