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
19 static unsigned int ifindex;
20 static __u32 attached_prog_id;
21 static bool attached_tc;
22
cleanup(int sig)23 static 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
usage(const char * progname)71 static 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
parse_arg_ul(const char * progname,const char * arg,unsigned long limit)78 static 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
parse_options(int argc,char * argv[],unsigned int * ifindex,__u32 * prog_id,__u64 * tcpipopts,char ** ports,bool * single,bool * tc)91 static 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, mss6, wscale, ttl;
108 unsigned int tcpipopts_mask = 0;
109
110 if (argc < 2)
111 usage(argv[0]);
112
113 *ifindex = 0;
114 *prog_id = 0;
115 *tcpipopts = 0;
116 *ports = NULL;
117 *single = false;
118
119 while (true) {
120 int opt;
121
122 opt = getopt_long(argc, argv, "", long_options, NULL);
123 if (opt == -1)
124 break;
125
126 switch (opt) {
127 case 'h':
128 usage(argv[0]);
129 break;
130 case 'i':
131 *ifindex = if_nametoindex(optarg);
132 if (*ifindex == 0)
133 usage(argv[0]);
134 break;
135 case 'x':
136 *prog_id = parse_arg_ul(argv[0], optarg, UINT32_MAX);
137 if (*prog_id == 0)
138 usage(argv[0]);
139 break;
140 case 4:
141 mss4 = parse_arg_ul(argv[0], optarg, UINT16_MAX);
142 tcpipopts_mask |= 1 << 0;
143 break;
144 case 6:
145 mss6 = parse_arg_ul(argv[0], optarg, UINT16_MAX);
146 tcpipopts_mask |= 1 << 1;
147 break;
148 case 'w':
149 wscale = parse_arg_ul(argv[0], optarg, 14);
150 tcpipopts_mask |= 1 << 2;
151 break;
152 case 't':
153 ttl = parse_arg_ul(argv[0], optarg, UINT8_MAX);
154 tcpipopts_mask |= 1 << 3;
155 break;
156 case 'p':
157 *ports = optarg;
158 break;
159 case 's':
160 *single = true;
161 break;
162 case 'c':
163 *tc = true;
164 break;
165 default:
166 usage(argv[0]);
167 }
168 }
169 if (optind < argc)
170 usage(argv[0]);
171
172 if (tcpipopts_mask == 0xf) {
173 if (mss4 == 0 || mss6 == 0 || wscale == 0 || ttl == 0)
174 usage(argv[0]);
175 *tcpipopts = (mss6 << 32) | (ttl << 24) | (wscale << 16) | mss4;
176 } else if (tcpipopts_mask != 0) {
177 usage(argv[0]);
178 }
179
180 if (*ifindex != 0 && *prog_id != 0)
181 usage(argv[0]);
182 if (*ifindex == 0 && *prog_id == 0)
183 usage(argv[0]);
184 }
185
syncookie_attach(const char * argv0,unsigned int ifindex,bool tc)186 static int syncookie_attach(const char *argv0, unsigned int ifindex, bool tc)
187 {
188 struct bpf_prog_info info = {};
189 __u32 info_len = sizeof(info);
190 char xdp_filename[PATH_MAX];
191 struct bpf_program *prog;
192 struct bpf_object *obj;
193 int prog_fd;
194 int err;
195
196 snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.bpf.o", argv0);
197 obj = bpf_object__open_file(xdp_filename, NULL);
198 err = libbpf_get_error(obj);
199 if (err < 0) {
200 fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));
201 return err;
202 }
203
204 err = bpf_object__load(obj);
205 if (err < 0) {
206 fprintf(stderr, "Error: bpf_object__open_file: %s\n", strerror(-err));
207 return err;
208 }
209
210 prog = bpf_object__find_program_by_name(obj, tc ? "syncookie_tc" : "syncookie_xdp");
211 if (!prog) {
212 fprintf(stderr, "Error: bpf_object__find_program_by_name: program was not found\n");
213 return -ENOENT;
214 }
215
216 prog_fd = bpf_program__fd(prog);
217
218 err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
219 if (err < 0) {
220 fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
221 goto out;
222 }
223 attached_tc = tc;
224 attached_prog_id = info.id;
225 signal(SIGINT, cleanup);
226 signal(SIGTERM, cleanup);
227 if (tc) {
228 LIBBPF_OPTS(bpf_tc_hook, hook,
229 .ifindex = ifindex,
230 .attach_point = BPF_TC_INGRESS);
231 LIBBPF_OPTS(bpf_tc_opts, opts,
232 .handle = 1,
233 .priority = 1,
234 .prog_fd = prog_fd);
235
236 err = bpf_tc_hook_create(&hook);
237 if (err < 0) {
238 fprintf(stderr, "Error: bpf_tc_hook_create: %s\n",
239 strerror(-err));
240 goto fail;
241 }
242 err = bpf_tc_attach(&hook, &opts);
243 if (err < 0) {
244 fprintf(stderr, "Error: bpf_tc_attach: %s\n",
245 strerror(-err));
246 goto fail;
247 }
248
249 } else {
250 err = bpf_xdp_attach(ifindex, prog_fd,
251 XDP_FLAGS_UPDATE_IF_NOEXIST, NULL);
252 if (err < 0) {
253 fprintf(stderr, "Error: bpf_set_link_xdp_fd: %s\n",
254 strerror(-err));
255 goto fail;
256 }
257 }
258 err = 0;
259 out:
260 bpf_object__close(obj);
261 return err;
262 fail:
263 signal(SIGINT, SIG_DFL);
264 signal(SIGTERM, SIG_DFL);
265 attached_prog_id = 0;
266 goto out;
267 }
268
syncookie_open_bpf_maps(__u32 prog_id,int * values_map_fd,int * ports_map_fd)269 static int syncookie_open_bpf_maps(__u32 prog_id, int *values_map_fd, int *ports_map_fd)
270 {
271 struct bpf_prog_info prog_info;
272 __u32 map_ids[8];
273 __u32 info_len;
274 int prog_fd;
275 int err;
276 int i;
277
278 *values_map_fd = -1;
279 *ports_map_fd = -1;
280
281 prog_fd = bpf_prog_get_fd_by_id(prog_id);
282 if (prog_fd < 0) {
283 fprintf(stderr, "Error: bpf_prog_get_fd_by_id: %s\n", strerror(-prog_fd));
284 return prog_fd;
285 }
286
287 prog_info = (struct bpf_prog_info) {
288 .nr_map_ids = 8,
289 .map_ids = (__u64)map_ids,
290 };
291 info_len = sizeof(prog_info);
292
293 err = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &info_len);
294 if (err != 0) {
295 fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
296 goto out;
297 }
298
299 if (prog_info.nr_map_ids < 2) {
300 fprintf(stderr, "Error: Found %u BPF maps, expected at least 2\n",
301 prog_info.nr_map_ids);
302 err = -ENOENT;
303 goto out;
304 }
305
306 for (i = 0; i < prog_info.nr_map_ids; i++) {
307 struct bpf_map_info map_info = {};
308 int map_fd;
309
310 err = bpf_map_get_fd_by_id(map_ids[i]);
311 if (err < 0) {
312 fprintf(stderr, "Error: bpf_map_get_fd_by_id: %s\n", strerror(-err));
313 goto err_close_map_fds;
314 }
315 map_fd = err;
316
317 info_len = sizeof(map_info);
318 err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len);
319 if (err != 0) {
320 fprintf(stderr, "Error: bpf_obj_get_info_by_fd: %s\n", strerror(-err));
321 close(map_fd);
322 goto err_close_map_fds;
323 }
324 if (strcmp(map_info.name, "values") == 0) {
325 *values_map_fd = map_fd;
326 continue;
327 }
328 if (strcmp(map_info.name, "allowed_ports") == 0) {
329 *ports_map_fd = map_fd;
330 continue;
331 }
332 close(map_fd);
333 }
334
335 if (*values_map_fd != -1 && *ports_map_fd != -1) {
336 err = 0;
337 goto out;
338 }
339
340 err = -ENOENT;
341
342 err_close_map_fds:
343 if (*values_map_fd != -1)
344 close(*values_map_fd);
345 if (*ports_map_fd != -1)
346 close(*ports_map_fd);
347 *values_map_fd = -1;
348 *ports_map_fd = -1;
349
350 out:
351 close(prog_fd);
352 return err;
353 }
354
main(int argc,char * argv[])355 int main(int argc, char *argv[])
356 {
357 int values_map_fd, ports_map_fd;
358 __u64 tcpipopts;
359 bool firstiter;
360 __u64 prevcnt;
361 __u32 prog_id;
362 char *ports;
363 bool single;
364 int err = 0;
365 bool tc;
366
367 parse_options(argc, argv, &ifindex, &prog_id, &tcpipopts, &ports,
368 &single, &tc);
369
370 if (prog_id == 0) {
371 if (!tc) {
372 err = bpf_xdp_query_id(ifindex, 0, &prog_id);
373 if (err < 0) {
374 fprintf(stderr, "Error: bpf_get_link_xdp_id: %s\n",
375 strerror(-err));
376 goto out;
377 }
378 }
379 if (prog_id == 0) {
380 err = syncookie_attach(argv[0], ifindex, tc);
381 if (err < 0)
382 goto out;
383 prog_id = attached_prog_id;
384 }
385 }
386
387 err = syncookie_open_bpf_maps(prog_id, &values_map_fd, &ports_map_fd);
388 if (err < 0)
389 goto out;
390
391 if (ports) {
392 __u16 port_last = 0;
393 __u32 port_idx = 0;
394 char *p = ports;
395
396 fprintf(stderr, "Replacing allowed ports\n");
397
398 while (p && *p != '\0') {
399 char *token = strsep(&p, ",");
400 __u16 port;
401
402 port = parse_arg_ul(argv[0], token, UINT16_MAX);
403 err = bpf_map_update_elem(ports_map_fd, &port_idx, &port, BPF_ANY);
404 if (err != 0) {
405 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
406 fprintf(stderr, "Failed to add port %u (index %u)\n",
407 port, port_idx);
408 goto out_close_maps;
409 }
410 fprintf(stderr, "Added port %u\n", port);
411 port_idx++;
412 }
413 err = bpf_map_update_elem(ports_map_fd, &port_idx, &port_last, BPF_ANY);
414 if (err != 0) {
415 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
416 fprintf(stderr, "Failed to add the terminator value 0 (index %u)\n",
417 port_idx);
418 goto out_close_maps;
419 }
420 }
421
422 if (tcpipopts) {
423 __u32 key = 0;
424
425 fprintf(stderr, "Replacing TCP/IP options\n");
426
427 err = bpf_map_update_elem(values_map_fd, &key, &tcpipopts, BPF_ANY);
428 if (err != 0) {
429 fprintf(stderr, "Error: bpf_map_update_elem: %s\n", strerror(-err));
430 goto out_close_maps;
431 }
432 }
433
434 if ((ports || tcpipopts) && attached_prog_id == 0 && !single)
435 goto out_close_maps;
436
437 prevcnt = 0;
438 firstiter = true;
439 while (true) {
440 __u32 key = 1;
441 __u64 value;
442
443 err = bpf_map_lookup_elem(values_map_fd, &key, &value);
444 if (err != 0) {
445 fprintf(stderr, "Error: bpf_map_lookup_elem: %s\n", strerror(-err));
446 goto out_close_maps;
447 }
448 if (firstiter) {
449 prevcnt = value;
450 firstiter = false;
451 }
452 if (single) {
453 printf("Total SYNACKs generated: %llu\n", value);
454 break;
455 }
456 printf("SYNACKs generated: %llu (total %llu)\n", value - prevcnt, value);
457 prevcnt = value;
458 sleep(1);
459 }
460
461 out_close_maps:
462 close(values_map_fd);
463 close(ports_map_fd);
464 out:
465 return err == 0 ? 0 : 1;
466 }
467
