1 /*
2  * Copyright (c) 2021, 2023, 2024 Omar Polo <op@omarpolo.com>
3  * Copyright (c) 2019 Renaud Allard <renaud@allard.it>
4  * Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv>
5  * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
6  * Copyright (c) 2008 Reyk Floeter <reyk@openbsd.org>
7  *
8  * Permission to use, copy, modify, and distribute this software for any
9  * purpose with or without fee is hereby granted, provided that the above
10  * copyright notice and this permission notice appear in all copies.
11  *
12  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
13  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
18  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19  */
20 
21 /*
22  * The routines to generate a certificate were derived from acme-client.
23  */
24 
25 #include "compat.h"
26 
27 #include <sys/types.h>
28 #include <sys/stat.h>
29 
30 #include <ctype.h>
31 #include <dirent.h>
32 #include <fcntl.h>
33 #include <limits.h>
34 #include <string.h>
35 #include <unistd.h>
36 
37 #include <openssl/ec.h>
38 #include <openssl/err.h>
39 #include <openssl/evp.h>
40 #include <openssl/obj_mac.h>
41 #include <openssl/pem.h>
42 #include <openssl/rsa.h>
43 #include <openssl/x509_vfy.h>
44 #include <openssl/x509v3.h>
45 
46 #include "certs.h"
47 #include "fs.h"
48 #include "iri.h"
49 
50 struct cstore cert_store;
51 
52 char		**identities;
53 static size_t	  id_len, id_cap;
54 
55 /*
56  * Default number of bits when creating a new RSA key.
57  */
58 #define KBITS 4096
59 
60 static int
61 identities_cmp(const void *a, const void *b)
62 {
63 	return (strcmp(a, b));
64 }
65 
66 static inline int
67 push_identity(const char *n)
68 {
69 	char	*name;
70 	void	*t;
71 	size_t	 newcap, i;
72 
73 	for (i = 0; i < id_len; ++i) {
74 		if (!strcmp(identities[i], n))
75 			return (0);
76 	}
77 
78 	/* id_cap is initilized to 8 in certs_init() */
79 	if (id_len >= id_cap - 1) {
80 		newcap = id_cap + 8;
81 		t = recallocarray(identities, id_cap, newcap,
82 		    sizeof(*identities));
83 		if (t == NULL)
84 			return (-1);
85 		identities = t;
86 		id_cap = newcap;
87 	}
88 
89 	if ((name = strdup(n)) == NULL)
90 		return (-1);
91 
92 	identities[id_len++] = name;
93 	return (0);
94 }
95 
96 static int
97 certs_cmp(const void *a, const void *b)
98 {
99 	const struct ccert	*ca = a, *cb = b;
100 	int			 r;
101 
102 	if ((r = strcmp(ca->host, cb->host)) != 0)
103 		return (r);
104 	if ((r = strcmp(ca->port, cb->port)) != 0)
105 		return (r);
106 	if ((r = strcmp(ca->path, cb->path)) != 0)
107 		return (r);
108 	if ((r = strcmp(ca->cert, cb->cert)) != 0)
109 		return (r);
110 
111 	if (ca->flags > cb->flags)
112 		return (+1);
113 	if (ca->flags < cb->flags)
114 		return (-1);
115 	return (0);
116 }
117 
118 static int
119 certs_store_add(struct cstore *cstore, const char *host, const char *port,
120     const char *path, const char *cert, int flags)
121 {
122 	struct ccert	*c;
123 	void		*t;
124 	size_t		 newcap;
125 
126 	if (cstore->len == cstore->cap) {
127 		newcap = cstore->cap + 8;
128 		t = recallocarray(cstore->certs, cstore->cap, newcap,
129 		    sizeof(*cstore->certs));
130 		if (t == NULL)
131 			return (-1);
132 		cstore->certs = t;
133 		cstore->cap = newcap;
134 	}
135 
136 	c = &cstore->certs[cstore->len];
137 	c->flags = flags;
138 	if ((c->host = strdup(host)) == NULL ||
139 	    (c->port = strdup(port)) == NULL ||
140 	    (c->path = strdup(path)) == NULL ||
141 	    (c->cert = strdup(cert)) == NULL) {
142 		free(c->host);
143 		free(c->port);
144 		free(c->path);
145 		free(c->cert);
146 		memset(c, 0, sizeof(*c));
147 	}
148 	cstore->len++;
149 
150 	return (0);
151 }
152 
153 static int
154 certs_store_parse_line(struct cstore *cstore, char *line)
155 {
156 	char		*host, *port, *path, *cert;
157 
158 	while (isspace((unsigned char)*line))
159 		++line;
160 	if (*line == '#' || *line == '\0')
161 		return (0);
162 
163 	host = line;
164 
165 	port = host + strcspn(host, " \t");
166 	if (*port == '\0')
167 		return (-1);
168 	*port++ = '\0';
169 	while (isspace((unsigned char)*port))
170 		++port;
171 
172 	path = port + strcspn(port, " \t");
173 	if (*path == '\0')
174 		return (-1);
175 	*path++ = '\0';
176 	while (isspace((unsigned char)*path))
177 		++path;
178 
179 	cert = path + strcspn(path, " \t");
180 	if (*cert == '\0')
181 		return (-1);
182 	*cert++ = '\0';
183 	while (isspace((unsigned char)*cert))
184 		++cert;
185 
186 	if (*cert == '\0')
187 		return (-1);
188 
189 	return (certs_store_add(cstore, host, port, path, cert, CERT_OK));
190 }
191 
192 int
193 certs_init(const char *certfile)
194 {
195 	struct dirent *dp;
196 	DIR	*certdir;
197 	FILE	*fp;
198 	char	*line = NULL;
199 	size_t	 linesize = 0;
200 	ssize_t	 linelen;
201 
202 	id_cap = 8;
203 	if ((identities = calloc(id_cap, sizeof(*identities))) == NULL)
204 		return (-1);
205 
206 	if ((certdir = opendir(cert_dir)) == NULL)
207 		return (-1);
208 
209 	while ((dp = readdir(certdir)) != NULL) {
210 		if (dp->d_type != DT_REG)
211 			continue;
212 		if (push_identity(dp->d_name) == -1) {
213 			closedir(certdir);
214 			return (-1);
215 		}
216 	}
217 	closedir(certdir);
218 	qsort(identities, id_len, sizeof(*identities), identities_cmp);
219 
220 	if ((fp = fopen(certfile, "r")) == NULL) {
221 		if (errno == ENOENT)
222 			return (0);
223 		return (-1);
224 	}
225 
226 	while ((linelen = getline(&line, &linesize, fp)) != -1) {
227 		if (line[linelen - 1] == '\n')
228 			line[--linelen] = '\0';
229 
230 		if (certs_store_parse_line(&cert_store, line) == -1) {
231 			fclose(fp);
232 			free(line);
233 			return (-1);
234 		}
235 	}
236 
237 	if (ferror(fp)) {
238 		fclose(fp);
239 		free(line);
240 		return (-1);
241 	}
242 
243 	qsort(cert_store.certs, cert_store.len, sizeof(*cert_store.certs),
244 	    certs_cmp);
245 
246 	fclose(fp);
247 	free(line);
248 	return (0);
249 }
250 
251 const char *
252 ccert(const char *name)
253 {
254 	size_t		 i;
255 
256 	for (i = 0; i < id_len; ++i) {
257 		if (!strcmp(name, identities[i]))
258 			return (identities[i]);
259 	}
260 
261 	return (NULL);
262 }
263 
264 /*
265  * Test whether the test path is under the certificate path.
266  */
267 static inline int
268 path_under(const char *cpath, const char *tpath)
269 {
270 	if (*cpath == '\0')
271 		return (1);
272 
273 	while (*cpath != '\0') {
274 		if (*tpath == '\0')
275 			return (0);
276 
277 		if (*cpath++ != *tpath++)
278 			return (0);
279 	}
280 
281 	if (*tpath == '\0' || *tpath == '/')
282 		return (1);
283 
284 	return (cpath[-1] == '/');
285 }
286 
287 static struct ccert *
288 find_cert_for(struct cstore *cstore, struct iri *iri, size_t *n)
289 {
290 	struct ccert	*c;
291 	size_t		 i;
292 
293 	for (i = 0; i < cstore->len; ++i) {
294 		c = &cstore->certs[i];
295 
296 		if (!strcmp(c->host, iri->iri_host) &&
297 		    !strcmp(c->port, iri->iri_portstr) &&
298 		    path_under(c->path, iri->iri_path)) {
299 			if (n)
300 				*n = i;
301 			return (c);
302 		}
303 	}
304 
305 	return (NULL);
306 }
307 
308 const char *
309 cert_for(struct iri *iri, int *temporary)
310 {
311 	struct ccert	*c;
312 
313 	*temporary = 0;
314 
315 	if ((c = find_cert_for(&cert_store, iri, NULL)) == NULL)
316 		return (NULL);
317 	if (c->flags & CERT_TEMP_DEL)
318 		return (NULL);
319 
320 	*temporary = !!(c->flags & CERT_TEMP);
321 	return (c->cert);
322 }
323 
324 static int
325 write_cert_file(void)
326 {
327 	struct ccert	*c;
328 	FILE		*fp;
329 	char		 sfn[PATH_MAX];
330 	size_t		 i;
331 	int		 fd, r;
332 
333 	strlcpy(sfn, certs_file_tmp, sizeof(sfn));
334 	if ((fd = mkstemp(sfn)) == -1 ||
335 	    (fp = fdopen(fd, "w")) == NULL) {
336 		if (fd != -1) {
337 			unlink(sfn);
338 			close(fd);
339 		}
340 		return (-1);
341 	}
342 
343 	for (i = 0; i < cert_store.len; ++i) {
344 		c = &cert_store.certs[i];
345 		if (c->flags & CERT_TEMP)
346 			continue;
347 
348 		r = fprintf(fp, "%s\t%s\t%s\t%s\n", c->host, c->port,
349 		    c->path, c->cert);
350 		if (r < 0) {
351 			fclose(fp);
352 			unlink(sfn);
353 			return (-1);
354 		}
355 	}
356 
357 	if (ferror(fp)) {
358 		fclose(fp);
359 		unlink(sfn);
360 		return (-1);
361 	}
362 
363 	if (fclose(fp) == EOF) {
364 		unlink(sfn);
365 		return (-1);
366 	}
367 
368 	if (rename(sfn, certs_file) == -1) {
369 		unlink(sfn);
370 		return (-1);
371 	}
372 
373 	return (0);
374 }
375 
376 static void
377 certs_delete(struct cstore *cstore, size_t n)
378 {
379 	struct ccert	*c;
380 
381 	c = &cstore->certs[n];
382 	free(c->host);
383 	free(c->port);
384 	free(c->path);
385 	free(c->cert);
386 
387 	cstore->len--;
388 
389 	if (n == cstore->len) {
390 		memset(&cstore->certs[n], 0, sizeof(*cstore->certs));
391 		return;
392 	}
393 
394 	memmove(&cstore->certs[n], &cstore->certs[n + 1],
395 	    sizeof(*cstore->certs) * (cstore->len - n));
396 	memset(&cstore->certs[cstore->len], 0, sizeof(*cstore->certs));
397 }
398 
399 int
400 cert_save_for(const char *cert, struct iri *i, int persist)
401 {
402 	struct ccert	*c;
403 	char		*d;
404 	int		 flags;
405 
406 	flags = persist ? 0 : CERT_TEMP;
407 
408 	if ((c = find_cert_for(&cert_store, i, NULL)) != NULL) {
409 		if ((d = strdup(cert)) == NULL)
410 			return (-1);
411 
412 		free(c->cert);
413 		c->cert = d;
414 		c->flags = flags;
415 	} else {
416 		if (certs_store_add(&cert_store, i->iri_host,
417 		    i->iri_portstr, i->iri_path, cert, flags) == -1)
418 			return (-1);
419 
420 		qsort(cert_store.certs, cert_store.len,
421 		    sizeof(*cert_store.certs), certs_cmp);
422 	}
423 
424 	if (persist && write_cert_file() == -1)
425 		return (-1);
426 
427 	return (0);
428 }
429 
430 int
431 cert_delete_for(const char *cert, struct iri *iri, int persist)
432 {
433 	struct ccert	*c;
434 	size_t		 i;
435 
436 	if ((c = find_cert_for(&cert_store, iri, &i)) == NULL)
437 		return (-1);
438 
439 	if (!persist) {
440 		c->flags |= CERT_TEMP_DEL;
441 		return (0);
442 	}
443 
444 	certs_delete(&cert_store, i);
445 	return (write_cert_file());
446 }
447 
448 int
449 cert_open(const char *cert)
450 {
451 	char		 path[PATH_MAX];
452 	struct stat	 sb;
453 	int		 fd;
454 
455 	strlcpy(path, cert_dir, sizeof(path));
456 	strlcat(path, "/", sizeof(path));
457 	strlcat(path, cert, sizeof(path));
458 
459 	if ((fd = open(path, O_RDONLY)) == -1)
460 		return (-1);
461 
462 	if (fstat(fd, &sb) == -1 || !S_ISREG(sb.st_mode)) {
463 		close(fd);
464 		return (-1);
465 	}
466 
467 	return (fd);
468 }
469 
470 static EVP_PKEY *
471 rsa_key_create(FILE *f)
472 {
473 	EVP_PKEY_CTX	*ctx = NULL;
474 	EVP_PKEY	*pkey = NULL;
475 	int		 ret = -1;
476 
477 	/* First, create the context and the key. */
478 
479 	if ((ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL)) == NULL)
480 		goto done;
481 
482 	if (EVP_PKEY_keygen_init(ctx) <= 0)
483 		goto done;
484 
485 	if (EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, KBITS) <= 0)
486 		goto done;
487 
488 	if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
489 		goto done;
490 
491 	/* Serialize the key to the disc. */
492 	if (!PEM_write_PrivateKey(f, pkey, NULL, NULL, 0, NULL, NULL))
493 		goto done;
494 
495 	ret = 0;
496  done:
497 	if (ret == -1) {
498 		EVP_PKEY_free(pkey);
499 		pkey = NULL;
500 	}
501 	EVP_PKEY_CTX_free(ctx);
502 	return pkey;
503 }
504 
505 static EVP_PKEY *
506 ec_key_create(FILE *f)
507 {
508 	EC_KEY		*eckey = NULL;
509 	EVP_PKEY	*pkey = NULL;
510 	int		 ret = -1;
511 
512 	if ((eckey = EC_KEY_new_by_curve_name(NID_secp384r1)) == NULL)
513 		goto done;
514 
515 	if (!EC_KEY_generate_key(eckey))
516 		goto done;
517 
518 	/* Serialise the key to the disc in EC format */
519 	if (!PEM_write_ECPrivateKey(f, eckey, NULL, NULL, 0, NULL, NULL))
520 		goto done;
521 
522 	/* Convert the EC key into a PKEY structure */
523 	if ((pkey = EVP_PKEY_new()) == NULL)
524 		goto done;
525 
526 	if (!EVP_PKEY_set1_EC_KEY(pkey, eckey))
527 		goto done;
528 
529 	ret = 0;
530  done:
531 	if (ret == -1) {
532 		EVP_PKEY_free(pkey);
533 		pkey = NULL;
534 	}
535 	EC_KEY_free(eckey);
536 	return pkey;
537 }
538 
539 int
540 cert_new(const char *common_name, const char *path, int eckey)
541 {
542 	EVP_PKEY	*pkey = NULL;
543 	X509		*x509 = NULL;
544 	X509_NAME	*name = NULL;
545 	FILE		*fp = NULL;
546 	int		 ret = -1;
547 	const unsigned char *cn = (const unsigned char*)common_name;
548 
549 	if ((fp = fopen(path, "wx")) == NULL)
550 		goto done;
551 
552 	if (eckey)
553 		pkey = ec_key_create(fp);
554 	else
555 		pkey = rsa_key_create(fp);
556 	if (pkey == NULL)
557 		goto done;
558 
559 	if ((x509 = X509_new()) == NULL)
560 		goto done;
561 
562 	ASN1_INTEGER_set(X509_get_serialNumber(x509), 0);
563 	X509_gmtime_adj(X509_get_notBefore(x509), 0);
564 	X509_gmtime_adj(X509_get_notAfter(x509), 315360000L); /* 10 years */
565 	X509_set_version(x509, 2); // v3
566 
567 	if (!X509_set_pubkey(x509, pkey))
568 		goto done;
569 
570 	if ((name = X509_NAME_new()) == NULL)
571 		goto done;
572 
573 	if (!X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, cn,
574 	    -1, -1, 0))
575 		goto done;
576 
577 	X509_set_subject_name(x509, name);
578 	X509_set_issuer_name(x509, name);
579 
580 	if (!X509_sign(x509, pkey, EVP_sha256()))
581 		goto done;
582 
583 	if (!PEM_write_X509(fp, x509))
584 		goto done;
585 
586 	if (fflush(fp) == EOF)
587 		goto done;
588 
589 	ret = 0;
590  done:
591 	if (pkey)
592 		EVP_PKEY_free(pkey);
593 	if (x509)
594 		X509_free(x509);
595 	if (name)
596 		X509_NAME_free(name);
597 	if (fp)
598 		fclose(fp);
599 	if (ret == -1)
600 		(void) unlink(path);
601 	return (ret);
602 }