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 
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 
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 
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 
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, 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 
187 static 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;
260 out:
261 	bpf_object__close(obj);
262 	return err;
263 fail:
264 	signal(SIGINT, SIG_DFL);
265 	signal(SIGTERM, SIG_DFL);
266 	attached_prog_id = 0;
267 	goto out;
268 }
269 
270 static 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 
343 err_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 
351 out:
352 	close(prog_fd);
353 	return err;
354 }
355 
356 int 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 
462 out_close_maps:
463 	close(values_map_fd);
464 	close(ports_map_fd);
465 out:
466 	return err == 0 ? 0 : 1;
467 }
468