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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
120 while (true) {
121 int opt;
122
123 opt = getopt_long(argc, argv, "", long_options, NULL);
124 if (opt == -1)
125 break;
126
127 switch (opt) {
128 case 'h':
129 usage(argv[0]);
130 break;
131 case 'i':
132 *ifindex = if_nametoindex(optarg);
133 if (*ifindex == 0)
134 usage(argv[0]);
135 break;
136 case 'x':
137 *prog_id = parse_arg_ul(argv[0], optarg, UINT32_MAX);
138 if (*prog_id == 0)
139 usage(argv[0]);
140 break;
141 case 4:
142 mss4 = parse_arg_ul(argv[0], optarg, UINT16_MAX);
143 tcpipopts_mask |= 1 << 0;
144 break;
145 case 6:
146 mss6 = parse_arg_ul(argv[0], optarg, UINT16_MAX);
147 tcpipopts_mask |= 1 << 1;
148 break;
149 case 'w':
150 wscale = parse_arg_ul(argv[0], optarg, 14);
151 tcpipopts_mask |= 1 << 2;
152 break;
153 case 't':
154 ttl = parse_arg_ul(argv[0], optarg, UINT8_MAX);
155 tcpipopts_mask |= 1 << 3;
156 break;
157 case 'p':
158 *ports = optarg;
159 break;
160 case 's':
161 *single = true;
162 break;
163 case 'c':
164 *tc = true;
165 break;
166 default:
167 usage(argv[0]);
168 }
169 }
170 if (optind < argc)
171 usage(argv[0]);
172
173 if (tcpipopts_mask == 0xf) {
174 if (mss4 == 0 || mss6 == 0 || wscale == 0 || ttl == 0)
175 usage(argv[0]);
176 *tcpipopts = (mss6 << 32) | (ttl << 24) | (wscale << 16) | mss4;
177 } else if (tcpipopts_mask != 0) {
178 usage(argv[0]);
179 }
180
181 if (*ifindex != 0 && *prog_id != 0)
182 usage(argv[0]);
183 if (*ifindex == 0 && *prog_id == 0)
184 usage(argv[0]);
185}
186
187static int syncookie_attach(const char *argv0, unsigned int ifindex, bool tc)
188{
189 struct bpf_prog_info info = {};
190 __u32 info_len = sizeof(info);
191 char xdp_filename[PATH_MAX];
192 struct bpf_program *prog;
193 struct bpf_object *obj;
194 int prog_fd;
195 int err;
196
197 snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.bpf.o", argv0);
198 obj = bpf_object__open_file(xdp_filename, NULL);
199 err = libbpf_get_error(obj);
200 if (err < 0) {
201 fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));
202 return err;
203 }
204
205 err = bpf_object__load(obj);
206 if (err < 0) {
207 fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));
208 return err;
209 }
210
211 prog = bpf_object__find_program_by_name(obj, tc ? "syncookie_tc" : "syncookie_xdp");
212 if (!prog) {
213 fprintf(stderr, "Error: bpf_object__find_program_by_name: program was not found\n");
214 return -ENOENT;
215 }
216
217 prog_fd = bpf_program__fd(prog);
218
219 err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
220 if (err < 0) {
221 fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
222 goto out;
223 }
224 attached_tc = tc;
225 attached_prog_id = info.id;
226 signal(SIGINT, cleanup);
227 signal(SIGTERM, cleanup);
228 if (tc) {
229 LIBBPF_OPTS(bpf_tc_hook, hook,
230 .ifindex = ifindex,
231 .attach_point = BPF_TC_INGRESS);
232 LIBBPF_OPTS(bpf_tc_opts, opts,
233 .handle = 1,
234 .priority = 1,
235 .prog_fd = prog_fd);
236
237 err = bpf_tc_hook_create(&hook);
238 if (err < 0) {
239 fprintf(stderr, "Error: bpf_tc_hook_create: %s\n",
240 strerror(-err));
241 goto fail;
242 }
243 err = bpf_tc_attach(&hook, &opts);
244 if (err < 0) {
245 fprintf(stderr, "Error: bpf_tc_attach: %s\n",
246 strerror(-err));
247 goto fail;
248 }
249
250 } else {
251 err = bpf_xdp_attach(ifindex, prog_fd,
252 XDP_FLAGS_UPDATE_IF_NOEXIST, NULL);
253 if (err < 0) {
254 fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n",
255 strerror(-err));
256 goto fail;
257 }
258 }
259 err = 0;
260out:
261 bpf_object__close(obj);
262 return err;
263fail:
264 signal(SIGINT, SIG_DFL);
265 signal(SIGTERM, SIG_DFL);
266 attached_prog_id = 0;
267 goto out;
268}
269
270static int syncookie_open_bpf_maps(__u32 prog_id, int *values_map_fd, int *ports_map_fd)
271{
272 struct bpf_prog_info prog_info;
273 __u32 map_ids[8];
274 __u32 info_len;
275 int prog_fd;
276 int err;
277 int i;
278
279 *values_map_fd = -1;
280 *ports_map_fd = -1;
281
282 prog_fd = bpf_prog_get_fd_by_id(prog_id);
283 if (prog_fd < 0) {
284 fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd));
285 return prog_fd;
286 }
287
288 prog_info = (struct bpf_prog_info) {
289 .nr_map_ids = 8,
290 .map_ids = (__u64)(unsigned long)map_ids,
291 };
292 info_len = sizeof(prog_info);
293
294 err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len);
295 if (err != 0) {
296 fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
297 goto out;
298 }
299
300 if (prog_info.nr_map_ids < 2) {
301 fprintf(stderr, "Error: Found %u BPF maps, expected at least 2\n",
302 prog_info.nr_map_ids);
303 err = -ENOENT;
304 goto out;
305 }
306
307 for (i = 0; i < prog_info.nr_map_ids; i++) {
308 struct bpf_map_info map_info = {};
309 int map_fd;
310
311 err = bpf_map_get_fd_by_id(map_ids[i]);
312 if (err < 0) {
313 fprintf(stderr, "Error: bpf_map_get_fd_by_id: %s\n", strerror(-err));
314 goto err_close_map_fds;
315 }
316 map_fd = err;
317
318 info_len = sizeof(map_info);
319 err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len);
320 if (err != 0) {
321 fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
322 close(map_fd);
323 goto err_close_map_fds;
324 }
325 if (strcmp(map_info.name, "values") == 0) {
326 *values_map_fd = map_fd;
327 continue;
328 }
329 if (strcmp(map_info.name, "allowed_ports") == 0) {
330 *ports_map_fd = map_fd;
331 continue;
332 }
333 close(map_fd);
334 }
335
336 if (*values_map_fd != -1 && *ports_map_fd != -1) {
337 err = 0;
338 goto out;
339 }
340
341 err = -ENOENT;
342
343err_close_map_fds:
344 if (*values_map_fd != -1)
345 close(*values_map_fd);
346 if (*ports_map_fd != -1)
347 close(*ports_map_fd);
348 *values_map_fd = -1;
349 *ports_map_fd = -1;
350
351out:
352 close(prog_fd);
353 return err;
354}
355
356int main(int argc, char *argv[])
357{
358 int values_map_fd, ports_map_fd;
359 __u64 tcpipopts;
360 bool firstiter;
361 __u64 prevcnt;
362 __u32 prog_id;
363 char *ports;
364 bool single;
365 int err = 0;
366 bool tc;
367
368 parse_options(argc, argv, &ifindex, &prog_id, &tcpipopts, &ports,
369 &single, &tc);
370
371 if (prog_id == 0) {
372 if (!tc) {
373 err = bpf_xdp_query_id(ifindex, 0, &prog_id);
374 if (err < 0) {
375 fprintf(stderr, "Error: bpf_get_link_xdp_id: %s\n",
376 strerror(-err));
377 goto out;
378 }
379 }
380 if (prog_id == 0) {
381 err = syncookie_attach(argv[0], ifindex, tc);
382 if (err < 0)
383 goto out;
384 prog_id = attached_prog_id;
385 }
386 }
387
388 err = syncookie_open_bpf_maps(prog_id, &values_map_fd, &ports_map_fd);
389 if (err < 0)
390 goto out;
391
392 if (ports) {
393 __u16 port_last = 0;
394 __u32 port_idx = 0;
395 char *p = ports;
396
397 fprintf(stderr, "Replacing allowed ports\n");
398
399 while (p && *p != '\0') {
400 char *token = strsep(&p, ",");
401 __u16 port;
402
403 port = parse_arg_ul(argv[0], token, UINT16_MAX);
404 err = bpf_map_update_elem(ports_map_fd, &port_idx, &port, BPF_ANY);
405 if (err != 0) {
406 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
407 fprintf(stderr, "Failed to add port %u (index %u)\n",
408 port, port_idx);
409 goto out_close_maps;
410 }
411 fprintf(stderr, "Added port %u\n", port);
412 port_idx++;
413 }
414 err = bpf_map_update_elem(ports_map_fd, &port_idx, &port_last, BPF_ANY);
415 if (err != 0) {
416 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
417 fprintf(stderr, "Failed to add the terminator value 0 (index %u)\n",
418 port_idx);
419 goto out_close_maps;
420 }
421 }
422
423 if (tcpipopts) {
424 __u32 key = 0;
425
426 fprintf(stderr, "Replacing TCP/IP options\n");
427
428 err = bpf_map_update_elem(values_map_fd, &key, &tcpipopts, BPF_ANY);
429 if (err != 0) {
430 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
431 goto out_close_maps;
432 }
433 }
434
435 if ((ports || tcpipopts) && attached_prog_id == 0 && !single)
436 goto out_close_maps;
437
438 prevcnt = 0;
439 firstiter = true;
440 while (true) {
441 __u32 key = 1;
442 __u64 value;
443
444 err = bpf_map_lookup_elem(values_map_fd, &key, &value);
445 if (err != 0) {
446 fprintf(stderr, "Error: bpf_map_lookup_elem: %s\n", strerror(-err));
447 goto out_close_maps;
448 }
449 if (firstiter) {
450 prevcnt = value;
451 firstiter = false;
452 }
453 if (single) {
454 printf("Total SYNACKs generated: %llu\n", value);
455 break;
456 }
457 printf("SYNACKs generated: %llu (total %llu)\n", value - prevcnt, value);
458 prevcnt = value;
459 sleep(1);
460 }
461
462out_close_maps:
463 close(values_map_fd);
464 close(ports_map_fd);
465out:
466 return err == 0 ? 0 : 1;
467}