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Date:: Thu Dec 15 11:17:03 2022 UTC
Message:: Remove HAVE_ED25519 now that we have ED25519 in LibreSSL
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1 /*
2  * Copyright (c) 2022 Martijn van Duren <martijn@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 #include <sys/types.h>
17 #include <sys/socket.h>
18 
19 #include <openssl/evp.h>
20 #include <openssl/pem.h>
21 #include <openssl/sha.h>
22 #include <openssl/err.h>
23 
24 #include <arpa/nameser.h>
25 
26 #include <ctype.h>
27 #include <errno.h>
28 #include <event.h>
29 #include <limits.h>
30 #include <netdb.h>
31 #include <opensmtpd.h>
32 #include <stdarg.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <time.h>
37 #include <unistd.h>
38 #include <asr.h>
39 
40 #include "unpack_dns.h"
41 #include "ltok.h"
42 
43 /*
44  * Use RFC8601 (Authentication-Results) codes instead of RFC6376 codes,
45  * since they're more expressive.
46  */
47 enum state {
48 	DKIM_UNKNOWN,
49 	DKIM_PASS,
50 	DKIM_FAIL,
51 	DKIM_POLICY,
52 	DKIM_NEUTRAL,
53 	DKIM_TEMPERROR,
54 	DKIM_PERMERROR
55 };
56 
57 struct signature {
58 	struct header *header;
59 	enum state state;
60 	const char *state_reason;
61 	int v;
62 	const char *a;
63 	size_t asz;
64 	int ak;
65 	int sephash;
66 	const EVP_MD *ah;
67 	char *b;
68 	size_t bsz;
69 	const char *bheader;
70 	/* Make sure padding bits for base64 decoding fit */
71 	char bh[EVP_MAX_MD_SIZE + (3 - (EVP_MAX_MD_SIZE % 3))];
72 	size_t bhsz;
73 	EVP_MD_CTX *bhctx;
74 	int c;
75 #define CANON_HEADER_SIMPLE	0
76 #define CANON_HEADER_RELAXED	1
77 #define CANON_HEADER		1
78 #define CANON_BODY_SIMPLE	0
79 #define CANON_BODY_RELAXED	1 << 1
80 #define CANON_BODY		1 << 1
81 #define CANON_DONE		1 << 2
82 	char d[HOST_NAME_MAX + 1];
83 	char **h;
84 	const char *i;
85 	size_t isz;
86 	ssize_t l;
87 	int q;
88 	char s[HOST_NAME_MAX + 1];
89 	time_t t;	/* Signature t=/timestamp */
90 #define KT_Y			1
91 #define KT_S			1 << 1
92 	int kt;		/* Key t=/Flags */
93 	time_t x;
94 	int z;
95 	struct event_asr *query;
96 	EVP_PKEY *p;
97 };
98 
99 struct header {
100 	struct message *msg;
101 	uint8_t readdone;
102 	uint8_t parsed;
103 	char *buf;
104 	size_t buflen;
105 	struct signature *sig;
106 };
107 
108 #define AUTHENTICATION_RESULTS_LINELEN 78
109 #define MIN(a, b) ((a) < (b) ? (a) : (b))
110 
111 struct message {
112 	struct osmtpd_ctx *ctx;
113 	FILE *origf;
114 	int parsing_headers;
115 	size_t body_whitelines;
116 	int has_body;
117 	struct header *header;
118 	size_t nheaders;
119 	int err;
120 	int readdone;
121 };
122 
123 void usage(void);
124 void dkim_err(struct message *, char *);
125 void dkim_errx(struct message *, char *);
126 void dkim_conf(const char *, const char *);
127 void dkim_dataline(struct osmtpd_ctx *, const char *);
128 void dkim_commit(struct osmtpd_ctx *);
129 void *dkim_message_new(struct osmtpd_ctx *);
130 void dkim_message_free(struct osmtpd_ctx *, void *);
131 void dkim_header_add(struct osmtpd_ctx *, const char *);
132 void dkim_signature_parse(struct header *);
133 void dkim_signature_parse_v(struct signature *, const char *, const char *);
134 void dkim_signature_parse_a(struct signature *, const char *, const char *);
135 void dkim_signature_parse_b(struct signature *, const char *, const char *);
136 void dkim_signature_parse_bh(struct signature *, const char *, const char *);
137 void dkim_signature_parse_c(struct signature *, const char *, const char *);
138 void dkim_signature_parse_d(struct signature *, const char *, const char *);
139 void dkim_signature_parse_h(struct signature *, const char *, const char *);
140 void dkim_signature_parse_i(struct signature *, const char *, const char *);
141 void dkim_signature_parse_l(struct signature *, const char *, const char *);
142 void dkim_signature_parse_q(struct signature *, const char *, const char *);
143 void dkim_signature_parse_s(struct signature *, const char *, const char *);
144 void dkim_signature_parse_t(struct signature *, const char *, const char *);
145 void dkim_signature_parse_x(struct signature *, const char *, const char *);
146 void dkim_signature_parse_z(struct signature *, const char *, const char *);
147 void dkim_signature_verify(struct signature *);
148 void dkim_signature_header(EVP_MD_CTX *, struct signature *, struct header *);
149 void dkim_signature_state(struct signature *, enum state, const char *);
150 const char *dkim_state2str(enum state);
151 void dkim_header_cat(struct osmtpd_ctx *, const char *);
152 void dkim_body_parse(struct message *, const char *);
153 void dkim_body_verify(struct signature *);
154 void dkim_rr_resolve(struct asr_result *, void *);
155 void dkim_message_verify(struct message *);
156 ssize_t dkim_ar_cat(char **ar, size_t *n, size_t aroff, const char *fmt, ...)
157     __attribute__((__format__ (printf, 4, 5)));
158 void dkim_ar_print(struct osmtpd_ctx *, const char *);
159 int dkim_key_text_parse(struct signature *, const char *);
160 
161 char *authservid;
162 EVP_ENCODE_CTX *ectx = NULL;
163 
164 int
165 main(int argc, char *argv[])
166 {
167 	if (argc != 1)
168 		osmtpd_errx(1, "Invalid argument count");
169 
170 	OpenSSL_add_all_digests();
171 
172 	if (pledge("tmppath stdio dns", NULL) == -1)
173 		osmtpd_err(1, "pledge");
174 
175 	if ((ectx = EVP_ENCODE_CTX_new()) == NULL)
176 		osmtpd_err(1, "EVP_ENCODE_CTX_new");
177 
178 	osmtpd_register_conf(dkim_conf);
179 	osmtpd_register_filter_dataline(dkim_dataline);
180 	osmtpd_register_filter_commit(dkim_commit);
181 	osmtpd_local_message(dkim_message_new, dkim_message_free);
182 	osmtpd_run();
183 
184 	return 0;
185 }
186 
187 void
188 dkim_conf(const char *key, const char *value)
189 {
190 	const char *end;
191 
192 	if (key == NULL) {
193 		if (authservid == NULL)
194 			osmtpd_errx(1, "Didn't receive admd config option");
195 		return;
196 	}
197 	if (strcmp(key, "admd") == 0 && authservid == NULL) {
198 		if ((authservid = strdup(value)) == NULL)
199 			osmtpd_err(1, "malloc");
200 		end = osmtpd_ltok_skip_value(authservid, 0);
201 		if (authservid + strlen(authservid) != end)
202 			osmtpd_errx(1, "Invalid authservid");
203 	}
204 }
205 
206 void
207 dkim_dataline(struct osmtpd_ctx *ctx, const char *line)
208 {
209 	struct message *msg = ctx->local_message;
210 	size_t i;
211 
212 	if (msg->err) {
213 		if (line[0] == '.' && line[1] =='\0') {
214 			msg->readdone = 1;
215 			osmtpd_filter_dataline(ctx, ".");
216 		}
217 		return;
218 	}
219 
220 	if (fprintf(msg->origf, "%s\n", line) < 0) {
221 		dkim_err(msg, "Couldn't write to tempfile");
222 		return;
223 	}
224 	if (line[0] == '.') {
225 		line++;
226 		if (line[0] == '\0') {
227 			msg->readdone = 1;
228 			for (i = 0; i < msg->nheaders; i++) {
229 				if (msg->header[i].sig == NULL)
230 					continue;
231 				dkim_body_verify(msg->header[i].sig);
232 			}
233 			dkim_message_verify(msg);
234 			return;
235 		}
236 	}
237 	if (msg->parsing_headers) {
238 		dkim_header_add(ctx, line);
239 		if (line[0] == '\0') {
240 			msg->parsing_headers = 0;
241 			for (i = 0; i < msg->nheaders; i++) {
242 				if (msg->header[i].sig == NULL)
243 					continue;
244 				if (msg->header[i].sig->query == NULL)
245 					dkim_signature_verify(
246 					    msg->header[i].sig);
247 			}
248 		}
249 		return;
250 	} else {
251 		dkim_body_parse(msg, line);
252 	}
253 }
254 
255 void
256 dkim_commit(struct osmtpd_ctx *ctx)
257 {
258 	struct message *msg = ctx->local_message;
259 
260 	if (msg->err)
261 		osmtpd_filter_disconnect(ctx, "Internal server error");
262 	else
263 		osmtpd_filter_proceed(ctx);
264 }
265 
266 void *
267 dkim_message_new(struct osmtpd_ctx *ctx)
268 {
269 	struct message *msg;
270 
271 	if ((msg = malloc(sizeof(*msg))) == NULL)
272 		osmtpd_err(1, NULL);
273 
274 	if ((msg->origf = tmpfile()) == NULL) {
275 		dkim_err(msg, "Can't open tempfile");
276 		return NULL;
277 	}
278 	msg->ctx = ctx;
279 	msg->parsing_headers = 1;
280 	msg->body_whitelines = 0;
281 	msg->has_body = 0;
282 	msg->header = NULL;
283 	msg->nheaders = 0;
284 	msg->err = 0;
285 	msg->readdone = 0;
286 
287 	return msg;
288 }
289 
290 void
291 dkim_message_free(struct osmtpd_ctx *ctx, void *data)
292 {
293 	struct message *msg = data;
294 	size_t i, j;
295 
296 	fclose(msg->origf);
297 	for (i = 0; i < msg->nheaders; i++) {
298 		if (msg->header[i].sig != NULL) {
299 			free(msg->header[i].sig->b);
300 			EVP_MD_CTX_free(msg->header[i].sig->bhctx);
301 			for (j = 0; msg->header[i].sig->h != NULL &&
302 			    msg->header[i].sig->h[j] != NULL; j++)
303 				free(msg->header[i].sig->h[j]);
304 			free(msg->header[i].sig->h);
305 			EVP_PKEY_free(msg->header[i].sig->p);
306 		}
307 		free(msg->header[i].buf);
308 		free(msg->header[i].sig);
309 	}
310 	free(msg->header);
311 	free(msg);
312 }
313 
314 void
315 dkim_header_add(struct osmtpd_ctx *ctx, const char *line)
316 {
317 	struct message *msg = ctx->local_message;
318 	const char *start, *end, *verify;
319 	struct header *headers;
320 	size_t i;
321 
322 	if (msg->nheaders > 0 &&
323 	    msg->header[msg->nheaders - 1].readdone == 0) {
324 		if (line[0] != ' ' && line[0] != '\t') {
325 			msg->header[msg->nheaders - 1].readdone = 1;
326 			start = msg->header[msg->nheaders - 1].buf;
327 			end = osmtpd_ltok_skip_field_name(start, 0);
328 			/* In case someone uses an obs-optional */
329 			if (end != NULL)
330 				verify = osmtpd_ltok_skip_wsp(end, 1);
331 			if (end != NULL &&
332 			    strncasecmp(
333 			    start, "DKIM-Signature", end - start) == 0 &&
334 			    verify[0] == ':')
335 				dkim_signature_parse(
336 				    &msg->header[msg->nheaders - 1]);
337 			if (line[0] == '\0')
338 				return;
339 		} else {
340 			dkim_header_cat(ctx, line);
341 			return;
342 		}
343 	}
344 	if (msg->nheaders % 10 == 0) {
345 		if ((headers = recallocarray(msg->header, msg->nheaders,
346 		    msg->nheaders + 10, sizeof(*msg->header))) == NULL) {
347 			dkim_err(msg, "malloc");
348 			return;
349 		}
350 		msg->header = headers;
351 		for (i = 0; i < msg->nheaders; i++) {
352 			if (msg->header[i].sig == NULL)
353 				continue;
354 			msg->header[i].sig->header = &msg->header[i];
355 		}
356 	}
357 	msg->header[msg->nheaders].msg = msg;
358 	msg->nheaders++;
359 	dkim_header_cat(ctx, line);
360 }
361 
362 void
363 dkim_header_cat(struct osmtpd_ctx *ctx, const char *line)
364 {
365 	struct message *msg = ctx->local_message;
366 	struct header *header = &msg->header[msg->nheaders - 1];
367 	char *buf;
368 
369 	size_t needed = header->buflen + strlen(line) + 2;
370 
371 	if (needed > (header->buflen / 1024) + 1) {
372 		buf = reallocarray(header->buf, (needed / 1024) + 1, 1024);
373 		if (buf == NULL) {
374 			dkim_err(msg, "malloc");
375 			return;
376 		}
377 		header->buf = buf;
378 	}
379 	header->buflen += snprintf(header->buf + header->buflen,
380 	    (((needed / 1024) + 1) * 1024) - header->buflen, "%s%s",
381 	    header->buflen == 0 ? "" : "\r\n", line);
382 }
383 
384 void
385 dkim_signature_parse(struct header *header)
386 {
387 	struct signature *sig;
388 	struct asr_query *query;
389 	const char *buf, *i, *end;
390 	char tagname[3];
391 	char subdomain[HOST_NAME_MAX + 1];
392 	size_t ilen, dlen;
393 
394 	/* Format checked by dkim_header_add */
395 	buf = osmtpd_ltok_skip_field_name(header->buf, 0);
396 	buf = osmtpd_ltok_skip_wsp(buf, 1) + 1;
397 
398 	if ((header->sig = calloc(1, sizeof(*header->sig))) == NULL) {
399 		dkim_err(header->msg, "malloc");
400 		return;
401 	}
402 	sig = header->sig;
403 	sig->header = header;
404 	sig->l = -1;
405 	sig->t = -1;
406 	sig->x = -1;
407 
408 	end = osmtpd_ltok_skip_tag_list(buf, 0);
409 	if (end == NULL || end[0] != '\0') {
410 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid tag-list");
411 		return;
412 	}
413 
414 	while (buf[0] != '\0') {
415 		buf = osmtpd_ltok_skip_fws(buf, 1);
416 		end = osmtpd_ltok_skip_tag_name(buf, 0);
417 
418 		/* Unknown tag-name */
419 		if ((size_t)(end - buf) >= sizeof(tagname))
420 			tagname[0] = '\0';
421 		else
422 			strlcpy(tagname, buf, (end - buf) + 1);
423 		buf = osmtpd_ltok_skip_fws(end, 1);
424 		/* '=' */
425 		buf = osmtpd_ltok_skip_fws(buf + 1, 1);
426 		end = osmtpd_ltok_skip_tag_value(buf, 1);
427 		if (strcmp(tagname, "v") == 0)
428 			dkim_signature_parse_v(sig, buf, end);
429 		else if (strcmp(tagname, "a") == 0)
430 			dkim_signature_parse_a(sig, buf, end);
431 		else if (strcmp(tagname, "b") == 0)
432 			dkim_signature_parse_b(sig, buf, end);
433 		else if (strcmp(tagname, "bh") == 0)
434 			dkim_signature_parse_bh(sig, buf, end);
435 		else if (strcmp(tagname, "c") == 0)
436 			dkim_signature_parse_c(sig, buf, end);
437 		else if (strcmp(tagname, "d") == 0)
438 			dkim_signature_parse_d(sig, buf, end);
439 		else if (strcmp(tagname, "h") == 0)
440 			dkim_signature_parse_h(sig, buf, end);
441 		else if (strcmp(tagname, "i") == 0)
442 			dkim_signature_parse_i(sig, buf, end);
443 		else if (strcmp(tagname, "l") == 0)
444 			dkim_signature_parse_l(sig, buf, end);
445 		else if (strcmp(tagname, "q") == 0)
446 			dkim_signature_parse_q(sig, buf, end);
447 		else if (strcmp(tagname, "s") == 0)
448 			dkim_signature_parse_s(sig, buf, end);
449 		else if (strcmp(tagname, "t") == 0)
450 			dkim_signature_parse_t(sig, buf, end);
451 		else if (strcmp(tagname, "x") == 0)
452 			dkim_signature_parse_x(sig, buf, end);
453 		else if (strcmp(tagname, "z") == 0)
454 			dkim_signature_parse_z(sig, buf, end);
455 
456 		buf = osmtpd_ltok_skip_fws(end, 1);
457 		if (buf[0] == ';')
458 			buf++;
459 		else if (buf[0] != '\0') {
460 			dkim_signature_state(sig, DKIM_PERMERROR,
461 			    "Invalid tag-list");
462 			return;
463 		}
464 	}
465 	if (sig->state != DKIM_UNKNOWN)
466 		return;
467 
468 	if (sig->v != 1)
469 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing v tag");
470 	else if (sig->ah == NULL)
471 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing a tag");
472 	else if (sig->b == NULL)
473 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing b tag");
474 	else if (sig->bhsz == 0)
475 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing bh tag");
476 	else if (sig->d[0] == '\0')
477 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing d tag");
478 	else if (sig->h == NULL)
479 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing h tag");
480 	else if (sig->s[0] == '\0')
481 		dkim_signature_state(sig, DKIM_PERMERROR, "Missing s tag");
482 	if (sig->state != DKIM_UNKNOWN)
483 		return;
484 
485 	if (sig->i != NULL) {
486 		i = osmtpd_ltok_skip_local_part(sig->i, 1) + 1;
487 		ilen = sig->isz - (size_t)(i - sig->i);
488 		dlen = strlen(sig->d);
489 		if (ilen < dlen) {
490 			dkim_signature_state(sig, DKIM_PERMERROR,
491 			    "i tag not subdomain of d");
492 			return;
493 		}
494 		i += ilen - dlen;
495 		if ((i[-1] != '.' && i[-1] != '@') ||
496 		    strncasecmp(i, sig->d, dlen) != 0) {
497 			dkim_signature_state(sig, DKIM_PERMERROR,
498 			    "i tag not subdomain of d");
499 			return;
500 		}
501 	}
502 	if (sig->t != -1 && sig->x != -1 && sig->t > sig->x) {
503 		dkim_signature_state(sig, DKIM_PERMERROR, "t tag after x tag");
504 		return;
505 	}
506 
507 	if ((size_t)snprintf(subdomain, sizeof(subdomain), "%s._domainkey.%s",
508 	    sig->s, sig->d) >= sizeof(subdomain)) {
509 		dkim_signature_state(sig, DKIM_PERMERROR,
510 		    "dns/txt query too long");
511 		return;
512 	}
513 
514 	if ((query = res_query_async(subdomain, C_IN, T_TXT, NULL)) == NULL) {
515 		dkim_err(header->msg, "res_query_async");
516 		return;
517 	}
518 	if ((sig->query = event_asr_run(query, dkim_rr_resolve, sig)) == NULL) {
519 		dkim_err(header->msg, "event_asr_run");
520 		asr_abort(query);
521 		return;
522 	}
523 }
524 
525 void
526 dkim_signature_parse_v(struct signature *sig, const char *start, const char *end)
527 {
528 	if (sig->v != 0) {	/* Duplicate tag */
529 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate v tag");
530 		return;
531 	}
532 	/* Unsupported version */
533 	if (start[0] != '1' || start + 1 != end)
534 		dkim_signature_state(sig, DKIM_NEUTRAL, "Unsupported v tag");
535 	else
536 		sig->v = 1;
537 }
538 
539 void
540 dkim_signature_parse_a(struct signature *sig, const char *start, const char *end)
541 {
542 	char ah[sizeof("sha256")];
543 
544 	if (sig->ah != NULL) {
545 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate a tag");
546 		return;
547 	}
548 
549 	if (osmtpd_ltok_skip_sig_a_tag_alg(start, 0) != end) {
550 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid a tag");
551 		return;
552 	}
553 	sig->a = start;
554 	sig->asz = (size_t)(end - start);
555 	if (strncmp(start, "rsa-", 4) == 0) {
556 		start += 4;
557 		sig->ak = EVP_PKEY_RSA;
558 		sig->sephash = 0;
559 	} else if (strncmp(start, "ed25519-", 8) == 0) {
560 		start += 8;
561 		sig->ak = EVP_PKEY_ED25519;
562 		sig->sephash = 1;
563 	} else {
564 		dkim_signature_state(sig, DKIM_NEUTRAL, "Unsuppored a tag k");
565 		return;
566 	}
567 	if ((size_t)(end - start) >= sizeof(ah)) {
568 		dkim_signature_state(sig, DKIM_NEUTRAL, "Unsuppored a tag h");
569 		return;
570 	}
571 	strlcpy(ah, start, sizeof(ah));
572 	ah[end - start] = '\0';
573 	if ((sig->ah = EVP_get_digestbyname(ah)) == NULL) {
574 		dkim_signature_state(sig, DKIM_NEUTRAL, "Unsuppored a tag h");
575 		return;
576 	}
577 	if ((sig->bhctx = EVP_MD_CTX_new()) == NULL) {
578 		dkim_err(sig->header->msg, "EVP_MD_CTX_new");
579 		return;
580 	}
581 	if (EVP_DigestInit_ex(sig->bhctx, sig->ah, NULL) <= 0) {
582 		dkim_err(sig->header->msg, "EVP_DigestInit_ex");
583 		return;
584 	}
585 }
586 
587 void
588 dkim_signature_parse_b(struct signature *sig, const char *start, const char *end)
589 {
590 	int decodesz;
591 
592 	if (sig->b != NULL) {
593 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate b tag");
594 		return;
595 	}
596 	sig->bheader = start;
597 	if ((sig->b = malloc((((end - start) / 4) + 1) * 3)) == NULL) {
598 		dkim_err(sig->header->msg, "malloc");
599 		return;
600 	}
601 	/* EVP_DecodeBlock doesn't handle internal whitespace */
602 	EVP_DecodeInit(ectx);
603 	if (EVP_DecodeUpdate(ectx, sig->b, &decodesz, start,
604 	    (int)(end - start)) == -1) {
605 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid b tag");
606 		return;
607 	}
608 	sig->bsz = decodesz;
609 	if (EVP_DecodeFinal(ectx, sig->b + sig->bsz,
610 	    &decodesz) == -1) {
611 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid b tag");
612 		return;
613 	}
614 	sig->bsz += decodesz;
615 }
616 
617 void
618 dkim_signature_parse_bh(struct signature *sig, const char *start, const char *end)
619 {
620 	const char *b64;
621 	size_t n;
622 	int decodesz;
623 
624 	if (sig->bhsz != 0) {
625 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate bh tag");
626 		return;
627 	}
628 	/*
629 	 * EVP_Decode* expects sig->bh to be large enough,
630 	 * so count the actual b64 characters.
631 	 */
632 	b64 = start;
633 	n = 0;
634 	while (1) {
635 		b64 = osmtpd_ltok_skip_fws(b64, 1);
636 		if (osmtpd_ltok_skip_alphadigitps(b64, 0) == NULL)
637 			break;
638 		n++;
639 		b64++;
640 	}
641 	if (b64[0] == '=') {
642 		n++;
643 		b64 = osmtpd_ltok_skip_fws(b64 + 1, 1);
644 		if (b64[0] == '=') {
645 			n++;
646 			b64++;
647 		}
648 	}
649 	/* Invalid tag value */
650 	if (b64 != end || n % 4 != 0 || (n / 4) * 3 > sizeof(sig->bh)) {
651 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid bh tag");
652 		return;
653 	}
654 	/* EVP_DecodeBlock doesn't handle internal whitespace */
655 	EVP_DecodeInit(ectx);
656 	if (EVP_DecodeUpdate(ectx, sig->bh, &decodesz, start,
657 	    (int)(end - start)) == -1) {
658 		/* Paranoia check */
659 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid bh tag");
660 		return;
661 	}
662 	sig->bhsz = decodesz;
663 	if (EVP_DecodeFinal(ectx, sig->bh + sig->bhsz, &decodesz) == -1) {
664 		/* Paranoia check */
665 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid bh tag");
666 		return;
667 	}
668 	sig->bhsz += decodesz;
669 }
670 
671 void
672 dkim_signature_parse_c(struct signature *sig, const char *start, const char *end)
673 {
674 	if (sig->c != 0) {
675 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate c tag");
676 		return;
677 	}
678 	if (strncmp(start, "simple", 6) == 0) {
679 		sig->c = CANON_HEADER_SIMPLE;
680 		start += 6;
681 	} else if (strncmp(start, "relaxed", 7) == 0) {
682 		sig->c = CANON_HEADER_RELAXED;
683 		start += 7;
684 	} else {
685 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid c tag");
686 		return;
687 	}
688 	if (start[0] == '/') {
689 		start++;
690 		if (strncmp(start, "simple", 6) == 0) {
691 			sig->c |= CANON_BODY_SIMPLE;
692 			start += 6;
693 		} else if (strncmp(start, "relaxed", 7) == 0) {
694 			sig->c |= CANON_BODY_RELAXED;
695 			start += 7;
696 		} else {
697 			dkim_signature_state(sig, DKIM_PERMERROR,
698 			    "Invalid c tag");
699 			return;
700 		}
701 	}
702 
703 	if (start != end) {
704 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid c tag");
705 		return;
706 	}
707 	sig->c |= CANON_DONE;
708 }
709 
710 void
711 dkim_signature_parse_d(struct signature *sig, const char *start, const char *end)
712 {
713 	if (sig->d[0] != '\0') {
714 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate d tag");
715 		return;
716 	}
717 	if (osmtpd_ltok_skip_sig_d_tag_value(start, 0) != end ||
718 	    (size_t)(end - start) >= sizeof(sig->d)) {
719 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid d tag");
720 		return;
721 	}
722 	strlcpy(sig->d, start, end - start + 1);
723 }
724 
725 void
726 dkim_signature_parse_h(struct signature *sig, const char *start, const char *end)
727 {
728 	const char *h;
729 	size_t n = 0;
730 
731 	if (sig->h != NULL) {
732 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate h tag");
733 		return;
734 	}
735 	if (osmtpd_ltok_skip_sig_h_tag_value(start, 0) < end) {
736 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid h tag");
737 		return;
738 	}
739 	h = start;
740 	while (1) {
741 		if ((h = osmtpd_ltok_skip_hdr_name(h, 0)) == NULL) {
742 			dkim_signature_state(sig, DKIM_PERMERROR,
743 			    "Invalid h tag");
744 			return;
745 		}
746 		n++;
747 		/* ';' is part of hdr-name */
748 		if (h > end) {
749 			h = end;
750 			break;
751 		}
752 		h = osmtpd_ltok_skip_fws(h, 1);
753 		if (h[0] != ':')
754 			break;
755 		h = osmtpd_ltok_skip_fws(h + 1, 1);
756 	}
757 	if ((sig->h = calloc(n + 1, sizeof(*sig->h))) == NULL) {
758 		dkim_err(sig->header->msg, "malloc");
759 		return;
760 	}
761 	n = 0;
762 	h = start;
763 	while (1) {
764 		h = osmtpd_ltok_skip_hdr_name(start, 0);
765 		/* ';' is part of hdr-name */
766 		if (h > end) {
767 			sig->h[n] = strndup(start, end - start);
768 			break;
769 		}
770 		if ((sig->h[n++] = strndup(start, h - start)) == NULL) {
771 			dkim_err(sig->header->msg, "malloc");
772 			return;
773 		}
774 		start = osmtpd_ltok_skip_fws(h, 1);
775 		if (start[0] != ':')
776 			break;
777 		start = osmtpd_ltok_skip_fws(start + 1, 1);
778 	}
779 }
780 
781 void
782 dkim_signature_parse_i(struct signature *sig, const char *start, const char *end)
783 {
784 	if (sig->i != NULL) {
785 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate i tag");
786 		return;
787 	}
788 	if (osmtpd_ltok_skip_sig_i_tag_value(start, 0) != end) {
789 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid i tag");
790 		return;
791 	}
792 	sig->i = start;
793 	sig->isz = (size_t)(end - start);
794 }
795 
796 void
797 dkim_signature_parse_l(struct signature *sig, const char *start, const char *end)
798 {
799 	long long l;
800 	char *lend;
801 
802 	if (sig->l != -1) {	/* Duplicate tag */
803 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate l tag");
804 		return;
805 	}
806 	errno = 0;
807 	l = strtoll(start, &lend, 10);
808 	/* > 76 digits in stroll is an overflow */
809 	if (osmtpd_ltok_skip_digit(start, 0) == NULL ||
810 	    lend != end || errno != 0) {
811 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid l tag");
812 		return;
813 	}
814 	if (l > SSIZE_MAX) {
815 		dkim_signature_state(sig, DKIM_PERMERROR, "l tag too large");
816 		return;
817 	}
818 	sig->l = (ssize_t)l;
819 }
820 
821 void
822 dkim_signature_parse_q(struct signature *sig, const char *start, const char *end)
823 {
824 	const char *qend;
825 
826 	if (sig->q != 0) {
827 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate q tag");
828 		return;
829 	}
830 
831 	while (1) {
832 		start = osmtpd_ltok_skip_fws(start, 1);
833 		qend = osmtpd_ltok_skip_sig_q_tag_method(start, 0);
834 		if (qend == NULL) {
835 			dkim_signature_state(sig, DKIM_PERMERROR, "Invalid q tag");
836 			return;
837 		}
838 		if (strncmp(start, "dns/txt", qend - start) == 0)
839 			sig->q = 1;
840 		start = osmtpd_ltok_skip_fws(qend, 1);
841 		if (start[0] != ':')
842 			break;
843 	}
844 	if (start != end) {
845 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid q tag");
846 		return;
847 	}
848 	if (sig->q != 1) {
849 		sig->q = 1;
850 		dkim_signature_state(sig, DKIM_NEUTRAL, "No useable q found");
851 		return;
852 	}
853 }
854 
855 void
856 dkim_signature_parse_s(struct signature *sig, const char *start, const char *end)
857 {
858 	if (sig->s[0] != '\0') {
859 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate s tag");
860 		return;
861 	}
862 	if (osmtpd_ltok_skip_selector(start, 0) != end) {
863 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid s tag");
864 		return;
865 	}
866 	strlcpy(sig->s, start, end - start + 1);
867 }
868 
869 void
870 dkim_signature_parse_t(struct signature *sig, const char *start, const char *end)
871 {
872 	char *tend;
873 
874 	if (sig->t != -1) {
875 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate t tag");
876 		return;
877 	}
878 	errno = 0;
879 	sig->t = strtoll(start, &tend, 10);
880 	if (osmtpd_ltok_skip_digit(start, 0) == NULL || tend != end ||
881 	    tend - start > 12 || errno != 0) {
882 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid t tag");
883 		return;
884 	}
885 }
886 
887 void
888 dkim_signature_parse_x(struct signature *sig, const char *start, const char *end)
889 {
890 	char *xend;
891 
892 	if (sig->x != -1) {
893 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate x tag");
894 		return;
895 	}
896 	errno = 0;
897 	sig->x = strtoll(start, &xend, 10);
898 	if (osmtpd_ltok_skip_digit(start, 0) == NULL || xend != end ||
899 	    xend - start > 12 || errno != 0) {
900 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid x tag");
901 		return;
902 	}
903 }
904 
905 void
906 dkim_signature_parse_z(struct signature *sig, const char *start, const char *end)
907 {
908 	if (sig->z != 0) {
909 		dkim_signature_state(sig, DKIM_PERMERROR, "Duplicate z tag");
910 		return;
911 	}
912 
913 	sig->z = 1;
914 	if (osmtpd_ltok_skip_sig_z_tag_value(start, 0) != end) {
915 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid z tag");
916 		return;
917 	}
918 }
919 
920 void
921 dkim_signature_verify(struct signature *sig)
922 {
923 	struct message *msg = sig->header->msg;
924 	static EVP_MD_CTX *bctx = NULL;
925 	char digest[EVP_MAX_MD_SIZE];
926 	unsigned int digestsz;
927 	const char *end;
928 	size_t i, header;
929 
930 	if (sig->state != DKIM_UNKNOWN)
931 		return;
932 
933 	if (bctx == NULL) {
934 		if ((bctx = EVP_MD_CTX_new()) == NULL) {
935 			dkim_errx(msg, "EVP_MD_CTX_new");
936 			return;
937 		}
938 	}
939 	EVP_MD_CTX_reset(bctx);
940 	if (!sig->sephash) {
941 		if (EVP_DigestVerifyInit(bctx, NULL, sig->ah, NULL,
942 		    sig->p) != 1) {
943 			dkim_errx(msg, "EVP_DigestVerifyInit");
944 			return;
945 		}
946 	} else {
947 		if (EVP_DigestInit_ex(bctx, sig->ah, NULL) != 1) {
948 			dkim_errx(msg, "EVP_DigestInit_ex");
949 			return;
950 		}
951 	}
952 
953 	for (i = 0; i < msg->nheaders; i++)
954 		msg->header[i].parsed = 0;
955 
956 	for (header = 0; sig->h[header] != NULL; header++) {
957 		for (i = msg->nheaders; i > 0; ) {
958 			i--;
959 			if (msg->header[i].parsed ||
960 			    strncasecmp(msg->header[i].buf, sig->h[header],
961 			    strlen(sig->h[header])) != 0 ||
962 			    msg->header[i].sig == sig)
963 				continue;
964 			end = osmtpd_ltok_skip_fws(
965 			    msg->header[i].buf + strlen(sig->h[header]), 1);
966 			if (end[0] != ':')
967 				continue;
968 			dkim_signature_header(bctx, sig, &(msg->header[i]));
969 			msg->header[i].parsed = 1;
970 		}
971 	}
972 	dkim_signature_header(bctx, sig, sig->header);
973 	if (!sig->sephash) {
974 		if (EVP_DigestVerifyFinal(bctx, sig->b, sig->bsz) != 1)
975 			dkim_signature_state(sig, DKIM_FAIL, "b mismatch");
976 	} else {
977 		if (EVP_DigestFinal_ex(bctx, digest, &digestsz) == 0) {
978 			dkim_errx(msg, "EVP_DigestFinal_ex");
979 			return;
980 		}
981 		if (EVP_DigestVerifyInit(bctx, NULL, NULL, NULL, sig->p) != 1) {
982 			dkim_errx(msg, "EVP_DigestVerifyInit");
983 			return;
984 		}
985 		switch (EVP_DigestVerify(bctx, sig->b, sig->bsz, digest,
986 		    digestsz)) {
987 		case 1:
988 			break;
989 		case 0:
990 			dkim_signature_state(sig, DKIM_FAIL, "b mismatch");
991 			break;
992 		default:
993 			dkim_errx(msg, "EVP_DigestVerify");
994 			return;
995 		}
996 	}
997 }
998 
999 /* EVP_DigestVerifyUpdate is a macro, so we can't alias this on a variable */
1000 #define dkim_b_digest_update(a, b, c)					\
1001 	(sig->sephash ? EVP_DigestUpdate((a), (b), (c)) :\
1002 	    EVP_DigestVerifyUpdate((a), (b), (c)))
1003 
1004 void
1005 dkim_signature_header(EVP_MD_CTX *bctx, struct signature *sig,
1006     struct header *header)
1007 {
1008 	char c;
1009 	const char *ptr = header->buf, *end;
1010 	int inhdrname = 1;
1011 	int canon = sig->c & CANON_HEADER;
1012 
1013 	for (ptr = header->buf; ptr[0] != '\0'; ptr++) {
1014 		if (inhdrname) {
1015 			if (canon == CANON_HEADER_RELAXED) {
1016 				ptr = osmtpd_ltok_skip_fws(ptr, 1);
1017 				c = tolower(ptr[0]);
1018 			} else
1019 				c = ptr[0];
1020 			if (c == ':') {
1021 				inhdrname = 0;
1022 				if (canon == CANON_HEADER_RELAXED)
1023 					ptr = osmtpd_ltok_skip_fws(
1024 					    ptr + 1, 1) - 1;
1025 			}
1026 			if (dkim_b_digest_update(bctx, &c, 1) == 0) {
1027 				dkim_errx(sig->header->msg,
1028 				    "dkim_b_digest_update");
1029 				return;
1030 			}
1031 			continue;
1032 		}
1033 		end = osmtpd_ltok_skip_fws(ptr, 1);
1034 		if (end == ptr) {
1035 			if (sig->header == header && ptr == sig->bheader) {
1036 				ptr = osmtpd_ltok_skip_tag_value(
1037 				    ptr, 0) - 1;
1038 				continue;
1039 			}
1040 			if (dkim_b_digest_update(bctx, ptr, 1) == 0) {
1041 				dkim_errx(sig->header->msg,
1042 				    "dkim_b_digest_update");
1043 				return;
1044 			}
1045 		} else {
1046 			if (canon == CANON_HEADER_RELAXED) {
1047 				if (end[0] == '\0')
1048 					continue;
1049 				if (dkim_b_digest_update(bctx, " ", 1) == 0) {
1050 					dkim_errx(sig->header->msg,
1051 					    "dkim_b_digest_update");
1052 					return;
1053 				}
1054 			} else {
1055 				if (dkim_b_digest_update(bctx, ptr,
1056 				    end - ptr) == 0) {
1057 					dkim_errx(sig->header->msg,
1058 					    "dkim_b_digest_update");
1059 					return;
1060 				}
1061 			}
1062 			ptr = end - 1;
1063 		}
1064 			
1065 	}
1066 	if (sig->header != header) {
1067 		if (dkim_b_digest_update(bctx, "\r\n", 2) == 0) {
1068 			dkim_errx(sig->header->msg, "dkim_b_digest_update");
1069 			return;
1070 		}
1071 	}
1072 }
1073 
1074 void
1075 dkim_signature_state(struct signature *sig, enum state state,
1076     const char *reason)
1077 {
1078 	if (sig->query != NULL) {
1079 		event_asr_abort(sig->query);
1080 		sig->query = NULL;
1081 	}
1082 	switch (sig->state) {
1083 	case DKIM_UNKNOWN:
1084 		break;
1085 	case DKIM_PASS:
1086 	case DKIM_FAIL:
1087 		osmtpd_errx(1, "Unexpected transition");
1088 	case DKIM_POLICY:
1089 		if (state == DKIM_PASS)
1090 			return;
1091 		break;
1092 	case DKIM_NEUTRAL:
1093 		if (state == DKIM_PASS)
1094 			return;
1095 		if (state == DKIM_TEMPERROR || state == DKIM_PERMERROR)
1096 			break;
1097 		osmtpd_errx(1, "Unexpected transition");
1098 	case DKIM_TEMPERROR:
1099 		if (state == DKIM_PERMERROR)
1100 			break;
1101 		return;
1102 	case DKIM_PERMERROR:
1103 		return;
1104 	}
1105 	sig->state = state;
1106 	sig->state_reason = reason;
1107 }
1108 
1109 const char *
1110 dkim_state2str(enum state state)
1111 {
1112 	switch (state)
1113 	{
1114 	case DKIM_UNKNOWN:
1115 		return "unknown";
1116 	case DKIM_PASS:
1117 		return "pass";
1118 	case DKIM_FAIL:
1119 		return "fail";
1120 	case DKIM_POLICY:
1121 		return "policy";
1122 	case DKIM_NEUTRAL:
1123 		return "neutral";
1124 	case DKIM_TEMPERROR:
1125 		return "temperror";
1126 	case DKIM_PERMERROR:
1127 		return "permerror";
1128 	}
1129 }
1130 
1131 void
1132 dkim_rr_resolve(struct asr_result *ar, void *arg)
1133 {
1134 	struct signature *sig = arg;
1135 	char key[UINT16_MAX + 1];
1136 	const char *rr_txt;
1137 	size_t keylen, cstrlen;
1138 	struct unpack pack;
1139 	struct dns_header h;
1140 	struct dns_query q;
1141 	struct dns_rr rr;
1142 
1143 	sig->query = NULL;
1144 
1145 	if (ar->ar_h_errno == TRY_AGAIN || ar->ar_h_errno == NO_RECOVERY) {
1146 		dkim_signature_state(sig, DKIM_TEMPERROR,
1147 		    hstrerror(ar->ar_h_errno));
1148 		goto verify;
1149 	}
1150 	if (ar->ar_h_errno != NETDB_SUCCESS) {
1151 		dkim_signature_state(sig, DKIM_PERMERROR,
1152 		    hstrerror(ar->ar_h_errno));
1153 		goto verify;
1154 	}
1155 
1156 	unpack_init(&pack, ar->ar_data, ar->ar_datalen);
1157 	if (unpack_header(&pack, &h) != 0 ||
1158 	    unpack_query(&pack, &q) != 0) {
1159 		dkim_signature_state(sig, DKIM_PERMERROR, "Invalid dns/txt");
1160 		goto verify;
1161 	}
1162 	for (; h.ancount > 0; h.ancount--) {
1163 		unpack_rr(&pack, &rr);
1164 		if (rr.rr_type != T_TXT)
1165 			continue;
1166 
1167 		keylen = 0;
1168 		rr_txt = rr.rr.other.rdata;
1169 		while (rr.rr.other.rdlen > 0) {
1170 			cstrlen = ((const unsigned char *)rr_txt)[0];
1171 			if (cstrlen >= rr.rr.other.rdlen ||
1172 			    keylen + cstrlen >= sizeof(key))
1173 				break;
1174 			/*
1175 			 * RFC 6376 Section 3.6.2.2
1176 			 * Strings in a TXT RR MUST be concatenated together
1177 			 * before use with no intervening whitespace.
1178 			 */
1179 			strlcpy(key + keylen, rr_txt + 1, cstrlen + 1);
1180 			rr.rr.other.rdlen -= (cstrlen + 1);
1181 			rr_txt += (cstrlen + 1);
1182 			keylen += cstrlen;
1183 		}
1184 		if (rr.rr.other.rdlen > 0)	/* Invalid TXT RDATA */
1185 			continue;
1186 
1187 		if (dkim_key_text_parse(sig, key))
1188 			break;
1189 	}
1190 
1191 	if (h.ancount == 0) {
1192 		dkim_signature_state(sig, DKIM_PERMERROR,
1193 		    "No matching key found");
1194 	} else {
1195 		/* Only verify if all headers have been read */
1196 		if (!sig->header->msg->parsing_headers)
1197 			dkim_signature_verify(sig);
1198 	}
1199  verify:
1200 	free(ar->ar_data);
1201 	dkim_message_verify(sig->header->msg);
1202 }
1203 
1204 int
1205 dkim_key_text_parse(struct signature *sig, const char *key)
1206 {
1207 	char tagname, *hashname;
1208 	const char *end, *tagvend;
1209 	char pkraw[UINT16_MAX] = "", pkimp[UINT16_MAX];
1210 	size_t pkrawlen = 0, pkoff, linelen;
1211 	int h = 0, k = 0, n = 0, p = 0, s = 0, t = 0, first = 1;
1212 	BIO *bio;
1213 	size_t pklen;
1214 	int tmp;
1215 
1216 	key = osmtpd_ltok_skip_fws(key, 1);
1217 	/* Validate syntax early */
1218 	if ((end = osmtpd_ltok_skip_tag_list(key, 0)) == NULL)
1219 		return 0;
1220 
1221 	while (key[0] != '\0') {
1222 		key = osmtpd_ltok_skip_fws(key, 1);
1223 		if ((end = osmtpd_ltok_skip_tag_name(key, 0)) == NULL)
1224 			return 0;
1225 
1226 		if ((size_t)(end - key) != 1)
1227 			tagname = '\0';
1228 		else
1229 			tagname = key[0];
1230 		key = osmtpd_ltok_skip_fws(end, 1);
1231 		/* '=' */
1232 		if (key[0] != '=')
1233 			return 0;
1234 		key = osmtpd_ltok_skip_fws(key + 1, 1);
1235 		if ((end = osmtpd_ltok_skip_tag_value(key, 0)) == NULL)
1236 			return 0;
1237 		switch (tagname) {
1238 		case 'v':
1239 			/*
1240 			 * RFC 6376 section 3.6.1, v=:
1241 			 * RECOMMENDED...This tag MUST be the first tag in the
1242 			 * record.
1243 			 */
1244 			if (!first ||
1245 			    osmtpd_ltok_skip_key_v_tag_value(key, 0) != end)
1246 				return 0;
1247 			key = end;
1248 			break;
1249 		case 'h':
1250 			if (h != 0)	/* Duplicate tag */
1251 				return 0;
1252 			/* Invalid tag value */
1253 			if (osmtpd_ltok_skip_key_h_tag_value(key, 0) != end)
1254 				return 0;
1255 			while (1) {
1256 				if ((tagvend = osmtpd_ltok_skip_key_h_tag_alg(
1257 				    key, 0)) == NULL)
1258 					break;
1259 				hashname = strndup(key, tagvend - key);
1260 				if (hashname == NULL) {
1261 					dkim_err(sig->header->msg, "malloc");
1262 					return 0;
1263 				}
1264 				if (EVP_get_digestbyname(hashname) == sig->ah) {
1265 					free(hashname);
1266 					h = 1;
1267 					break;
1268 				}
1269 				free(hashname);
1270 				key = osmtpd_ltok_skip_fws(tagvend, 1);
1271 				if (key[0] != ':')
1272 					break;
1273 				key = osmtpd_ltok_skip_fws(key + 1, 1);
1274 			}
1275 			if (h != 1)
1276 				return 0;
1277 			key = end;
1278 			break;
1279 		case 'k':
1280 			if (k != 0)	/* Duplicate tag */
1281 				return 0;
1282 			k = 1;
1283 			if (strncmp(key, "rsa", end - key) == 0) {
1284 				if (sig->ak != EVP_PKEY_RSA)
1285 					return 0;
1286 			} else if (strncmp(key, "ed25519", end - key) == 0) {
1287 				if (sig->ak != EVP_PKEY_ED25519)
1288 					return 0;
1289 			} else
1290 				return 0;
1291 			key = end;
1292 			break;
1293 		case 'n':
1294 			if (n != 0)	/* Duplicate tag */
1295 				return 0;
1296 			n = 1;
1297 			/* semicolon is part of safe-char */
1298 			if (osmtpd_ltok_skip_key_n_tag_value(key, 0) < end)
1299 				return 0;
1300 			key = end;
1301 			break;
1302 		case 'p':
1303 			if (p != 0)	/* Duplicate tag */
1304 				return 0;
1305 			p = 1;
1306 			while (1) {
1307 				key = osmtpd_ltok_skip_fws(key, 1);
1308 				if (osmtpd_ltok_skip_alphadigitps(
1309 				    key, 0) == NULL)
1310 					break;
1311 				pkraw[pkrawlen++] = key++[0];
1312 				if (pkrawlen >= sizeof(pkraw))
1313 					return 0;
1314 			}
1315 			if (key[0] == '=') {
1316 				pkraw[pkrawlen++] = '=';
1317 				key = osmtpd_ltok_skip_fws(key + 1, 1);
1318 				if (pkrawlen >= sizeof(pkraw))
1319 					return 0;
1320 				if (key[0] == '=') {
1321 					pkraw[pkrawlen++] = '=';
1322 					key++;
1323 					if (pkrawlen >= sizeof(pkraw))
1324 						return 0;
1325 				}
1326 			}
1327 			/* Invalid tag value */
1328 			if (pkrawlen % 4 != 0 || key != end)
1329 				return 0;
1330 			break;
1331 		case 's':
1332 			if (s != 0)	/* Duplicate tag */
1333 				return 0;
1334 			/* Invalid tag value */
1335 			if (osmtpd_ltok_skip_key_s_tag_value(key, 0) != end)
1336 				return 0;
1337 			while (1) {
1338 				if ((tagvend =
1339 				    osmtpd_ltok_skip_key_s_tag_type(
1340 				    key, 0)) == NULL)
1341 					break;
1342 				if (strncmp(key, "*", tagvend - key) == 0 ||
1343 				    strncmp(key, "email", tagvend - key) == 0) {
1344 					s = 1;
1345 					break;
1346 				}
1347 				key = osmtpd_ltok_skip_fws(tagvend, 1);
1348 				if (key[0] != ':')
1349 					break;
1350 				key = osmtpd_ltok_skip_fws(key + 1, 1);
1351 			}
1352 			if (s != 1)
1353 				return 0;
1354 			key = end;
1355 			break;
1356 		case 't':
1357 			if (t != 0)	/* Duplicate tag */
1358 				return 0;
1359 			t = 1;
1360 			if (osmtpd_ltok_skip_key_t_tag_value(key, 0) != end)
1361 				return 0;
1362 			while (1) {
1363 				tagvend = osmtpd_ltok_skip_key_t_tag_flag(
1364 				    key, 0);
1365 				if (strncmp(key, "y", tagvend - key) == 0)
1366 					sig->kt |= KT_Y;
1367 				else if (strncmp(key, "s", tagvend - key) == 0)
1368 					sig->kt |= KT_S;
1369 				key = osmtpd_ltok_skip_fws(tagvend, 1);
1370 				if (key[0] != ':')
1371 					break;
1372 				key = osmtpd_ltok_skip_fws(key + 1, 1);
1373 			}
1374 			break;
1375 		default:
1376 			key = end;
1377 			break;
1378 		}
1379 
1380 		first = 0;
1381 		key = osmtpd_ltok_skip_fws(key, 1);
1382 		if (key[0] == ';')
1383 			key++;
1384 		else if (key[0] != '\0')
1385 			return 0;
1386 	}
1387 
1388 	if (!p)					/* Missing tag */
1389 		return 0;
1390 	if (k == 0 && sig->ak != EVP_PKEY_RSA)	/* Default to RSA */
1391 		return 0;
1392 
1393 	if (pkraw[0] == '\0') {
1394 		dkim_signature_state(sig, DKIM_PERMERROR, "Key is revoked");
1395 		return 1;
1396 	}
1397 
1398 	switch (sig->ak) {
1399 	case EVP_PKEY_RSA:
1400 		pkoff = strlcpy(pkimp, "-----BEGIN PUBLIC KEY-----\n",
1401 		    sizeof(pkimp));
1402 		linelen = 0;
1403 		for (key = pkraw; key[0] != '\0';) {
1404 			if (pkoff + 2 >= sizeof(pkimp))
1405 				return 0;
1406 			pkimp[pkoff++] = key++[0];
1407 			if (++linelen == 64) {
1408 				pkimp[pkoff++] = '\n';
1409 				linelen = 0;
1410 			}
1411 		}
1412 		/* Leverage pkoff check in loop */
1413 		if (linelen != 0)
1414 			pkimp[pkoff++] = '\n';
1415 		/* PEM_read_bio_PUBKEY will catch truncated keys */
1416 		pkoff += strlcpy(pkimp + pkoff, "-----END PUBLIC KEY-----\n",
1417 		    sizeof(pkimp) - pkoff);
1418 		if ((bio = BIO_new_mem_buf(pkimp, pkoff)) == NULL) {
1419 			dkim_err(sig->header->msg, "BIO_new_mem_buf");
1420 			return 1;
1421 		}
1422 		sig->p = PEM_read_bio_PUBKEY(bio, NULL, NULL, NULL);
1423 		BIO_free(bio);
1424 		break;
1425 	case EVP_PKEY_ED25519:
1426 		if ((pkrawlen / 4) * 3 >= sizeof(pkimp))
1427 			return 0;
1428 		EVP_DecodeInit(ectx);
1429 		if (EVP_DecodeUpdate(ectx, pkimp, &tmp, pkraw, pkrawlen) == -1)
1430 			return 0;
1431 		pklen = tmp;
1432 		if (EVP_DecodeFinal(ectx, pkimp, &tmp) == -1)
1433 			return 0;
1434 		pklen += tmp;
1435 		sig->p = EVP_PKEY_new_raw_public_key(sig->ak, NULL, pkimp,
1436 		    pklen);
1437 		break;
1438 	}
1439 	if (sig->p == NULL) {
1440 		/*
1441 		 * XXX No clue how to differentiate between invalid key and
1442 		 * temporary failure like *alloc.
1443 		 * Assume invalid key, because it's more likely.
1444 		 */
1445 		return 0;
1446 	}
1447 	return 1;
1448 }
1449 
1450 void
1451 dkim_body_parse(struct message *msg, const char *line)
1452 {
1453 	struct signature *sig;
1454 	const char *end = line, *hash, *prev;
1455 	size_t hashn, len, i;
1456 	int wsp, ret;
1457 
1458 	if (line[0] == '\0') {
1459 		msg->body_whitelines++;
1460 		return;
1461 	}
1462 
1463 	while (msg->body_whitelines-- > 0) {
1464 		for (i = 0; i < msg->nheaders; i++) {
1465 			if ((sig = msg->header[i].sig) == NULL ||
1466 			    sig->state != DKIM_UNKNOWN)
1467 				continue;
1468 			hashn = sig->l == -1 ? 2 : MIN(2, sig->l);
1469 			sig->l -= sig->l == -1 ? 0 : hashn;
1470 			if (EVP_DigestUpdate(sig->bhctx, "\r\n", hashn) == 0) {
1471 				dkim_errx(msg, "EVP_DigestUpdate");
1472 				return;
1473 			}
1474 		}
1475 	}
1476 	msg->body_whitelines = 0;
1477 	msg->has_body = 1;
1478 
1479 	while (line[0] != '\0') {
1480 		while (1) {
1481 			prev = end;
1482 			if ((end = osmtpd_ltok_skip_wsp(end, 0)) == NULL)
1483 				break;
1484 		}
1485 		end = prev;
1486 		wsp = end != line;
1487 		if (!wsp) {
1488 			while (osmtpd_ltok_skip_wsp(end, 0) == NULL &&
1489 			    end[0] != '\0')
1490 				end++;
1491 		}
1492 		for (i = 0; i < msg->nheaders; i++) {
1493 			sig = msg->header[i].sig;
1494 			if (sig == NULL || sig->state != DKIM_UNKNOWN)
1495 				continue;
1496 			if (wsp &&
1497 			    (sig->c & CANON_BODY) == CANON_BODY_RELAXED) {
1498 				hash = " ";
1499 				len = end[0] == '\0' ? 0 : 1;
1500 			} else {
1501 				hash = line;
1502 				len = (size_t)(end - line);
1503 			}
1504 			hashn = sig->l == -1 ? len : MIN(len, (size_t)sig->l);
1505 			sig->l -= sig->l == -1 ? 0 : hashn;
1506 			ret = EVP_DigestUpdate(sig->bhctx, hash, hashn);
1507 			if (ret == 0) {
1508 				dkim_errx(msg, "EVP_DigestUpdate");
1509 				return;
1510 			}
1511 		}
1512 		line = end;
1513 	}
1514 	for (i = 0; i < msg->nheaders; i++) {
1515 		sig = msg->header[i].sig;
1516 		if (sig == NULL || sig->state != DKIM_UNKNOWN)
1517 			continue;
1518 		hashn = sig->l == -1 ? 2 : MIN(2, sig->l);
1519 		sig->l -= sig->l == -1 ? 0 : hashn;
1520 		ret = EVP_DigestUpdate(sig->bhctx, "\r\n", hashn);
1521 		if (ret == 0) {
1522 			dkim_errx(msg, "EVP_DigestUpdate");
1523 			return;
1524 		}
1525 	}
1526 }
1527 
1528 void
1529 dkim_body_verify(struct signature *sig)
1530 {
1531 	unsigned char digest[EVP_MAX_MD_SIZE];
1532 	unsigned int digestsz;
1533 
1534 	if (sig->state != DKIM_UNKNOWN)
1535 		return;
1536 
1537 	if ((sig->c & CANON_BODY) == CANON_BODY_SIMPLE &&
1538 	    !sig->header->msg->has_body) {
1539 		if (EVP_DigestUpdate(sig->bhctx, "\r\n",
1540 		    sig->l == -1 ? 2 : MIN(2, sig->l)) <= 0) {
1541 			dkim_errx(sig->header->msg,
1542 			    "Can't update hash context");
1543 			return;
1544 		}
1545 	}
1546 	if (sig->l > 0) {
1547 		dkim_signature_state(sig, DKIM_PERMERROR,
1548 		    "l tag larger than body");
1549 		return;
1550 	}
1551 
1552 	if (EVP_DigestFinal_ex(sig->bhctx, digest, &digestsz) == 0) {
1553 		dkim_errx(sig->header->msg, "EVP_DigestFinal_ex");
1554 		return;
1555 	}
1556 
1557 	if (digestsz != sig->bhsz || memcmp(digest, sig->bh, digestsz) != 0)
1558 		dkim_signature_state(sig, DKIM_FAIL, "bh mismatch");
1559 }
1560 
1561 void
1562 dkim_message_verify(struct message *msg)
1563 {
1564 	struct signature *sig;
1565 	size_t i;
1566 	ssize_t n, aroff = 0;
1567 	int found = 0;
1568 	char *line = NULL;
1569 	size_t linelen = 0;
1570 
1571 	if (!msg->readdone)
1572 		return;
1573 
1574 	for (i = 0; i < msg->nheaders; i++) {
1575 		if (msg->header[i].sig == NULL)
1576 			continue;
1577 		if (msg->header[i].sig->query != NULL)
1578 			return;
1579 		if (msg->header[i].sig->state != DKIM_UNKNOWN)
1580 			continue;
1581 		dkim_signature_state(msg->header[i].sig, DKIM_PASS, NULL);
1582 	}
1583 	
1584 	if ((aroff = dkim_ar_cat(&line, &linelen, aroff,
1585 	    "Authentication-Results: %s", authservid)) == -1) {
1586 		dkim_err(msg, "malloc");
1587 		goto fail;
1588 	}
1589 	for (i = 0; i < msg->nheaders; i++) {
1590 		sig = msg->header[i].sig;
1591 		if (sig == NULL)
1592 			continue;
1593 		found = 1;
1594 		if ((aroff = dkim_ar_cat(&line, &linelen, aroff, "; dkim=%s",
1595 		    dkim_state2str(sig->state))) == -1) {
1596 			dkim_err(msg, "malloc");
1597 			goto fail;
1598 		}
1599 		if (sig->state_reason != NULL) {
1600 			if ((aroff = dkim_ar_cat(&line, &linelen, aroff,
1601 			    " reason=\"%s\"", sig->state_reason)) == -1) {
1602 				dkim_err(msg, "malloc");
1603 				goto fail;
1604 			}
1605 		}
1606 		if (sig->s[0] != '\0') {
1607 			if ((aroff = dkim_ar_cat(&line, &linelen, aroff,
1608 			    " header.s=%s", sig->s)) == -1) {
1609 				dkim_err(msg, "malloc");
1610 				goto fail;
1611 			}
1612 		}
1613 		if (sig->d[0] != '\0') {
1614 			if ((aroff = dkim_ar_cat(&line, &linelen, aroff,
1615 			    " header.d=%s", sig->d)) == -1) {
1616 				dkim_err(msg, "malloc");
1617 				goto fail;
1618 			}
1619 		}
1620 		/*
1621 		 * Don't print i-tag, since localpart can be a quoted-string,
1622 		 * which can contain FWS and CFWS.
1623 		 */
1624 		if (sig->a != NULL) {
1625 			if ((aroff = dkim_ar_cat(&line, &linelen, aroff,
1626 			    " header.a=%.*s", (int)sig->asz, sig->a)) == -1) {
1627 				dkim_err(msg, "malloc");
1628 				goto fail;
1629 			}
1630 		}
1631 	}
1632 	if (!found) {
1633 		aroff = dkim_ar_cat(&line, &linelen, aroff, "; dkim=none");
1634 		if (aroff == -1) {
1635 			dkim_err(msg, "malloc");
1636 			goto fail;
1637 		}
1638 	}
1639 	dkim_ar_print(msg->ctx, line);
1640 
1641 	rewind(msg->origf);
1642 	while ((n = getline(&line, &linelen, msg->origf)) != -1) {
1643 		line[n - 1] = '\0';
1644 		osmtpd_filter_dataline(msg->ctx, "%s", line);
1645 	}
1646 	if (ferror(msg->origf))
1647 		dkim_err(msg, "getline");
1648  fail:
1649 	free(line);
1650 	return;
1651 }
1652 
1653 void
1654 dkim_ar_print(struct osmtpd_ctx *ctx, const char *start)
1655 {
1656 	const char *scan, *checkpoint, *ncheckpoint;
1657 	size_t arlen = 0;
1658 	int first = 1, arid = 1;
1659 
1660 	checkpoint = start;
1661 	ncheckpoint = osmtpd_ltok_skip_hdr_name(start, 0) + 1;
1662 	for (scan = start; scan[0] != '\0'; scan++) {
1663 		if (scan[0] == '\t')
1664 			arlen = (arlen + 8) & ~7;
1665 		else
1666 			arlen++;
1667 		if (arlen >= AUTHENTICATION_RESULTS_LINELEN) {
1668 			osmtpd_filter_dataline(ctx, "%s%.*s", first ? "" : "\t",
1669 			    (int)((checkpoint == start ?
1670 			    ncheckpoint : checkpoint) - start), start);
1671 			start = osmtpd_ltok_skip_cfws(checkpoint, 1);
1672 			scan = start;
1673 			arlen = 8;
1674 			first = 0;
1675 		}
1676 		if (scan == ncheckpoint) {
1677 			checkpoint = ncheckpoint;
1678 			ncheckpoint = osmtpd_ltok_skip_cfws(ncheckpoint, 1);
1679 			/* authserv-id */
1680 			if (arid) {
1681 				ncheckpoint = osmtpd_ltok_skip_value(
1682 				    ncheckpoint, 0);
1683 				arid = 0;
1684 			/* methodspec */
1685 			} else if (strncmp(ncheckpoint, "dkim",
1686 			    sizeof("dkim") - 1) == 0) {
1687 				ncheckpoint = osmtpd_ltok_skip_keyword(
1688 				    ncheckpoint + sizeof("dkim"), 0);
1689 			/* reasonspec */
1690 			} else if (strncmp(ncheckpoint, "reason",
1691 			    sizeof("reason") - 1) == 0) {
1692 				ncheckpoint = osmtpd_ltok_skip_value(
1693 				    ncheckpoint + sizeof("reason"), 0);
1694 			/* propspec */
1695 			} else {
1696 				ncheckpoint += sizeof("header.x=") - 1;
1697 				ncheckpoint = osmtpd_ltok_skip_ar_pvalue(
1698 				    ncheckpoint, 0);
1699 				if (ncheckpoint[0] == ';')
1700 					ncheckpoint++;
1701 			}
1702 		}
1703 	}
1704 	osmtpd_filter_dataline(ctx, "%s%s", first ? "" : "\t", start);
1705 }
1706 
1707 ssize_t
1708 dkim_ar_cat(char **ar, size_t *n, size_t aroff, const char *fmt, ...)
1709 {
1710 	va_list ap;
1711 	char *artmp;
1712 	int size;
1713 	size_t nn;
1714 
1715 	va_start(ap, fmt);
1716 	size = vsnprintf(*ar + aroff, *n - aroff, fmt, ap);
1717 	va_end(ap);
1718 	if (size + aroff <= *n)
1719 		return (ssize_t)size + aroff;
1720 	nn = (((aroff + size)  / 256) + 1) * 256;
1721 	artmp = realloc(*ar, nn);
1722 	if (artmp == NULL)
1723 		return -1;
1724 	*ar = artmp;
1725 	*n = nn;
1726 	va_start(ap, fmt);
1727 	size = vsnprintf(*ar + aroff, *n - aroff, fmt, ap);
1728 	va_end(ap);
1729 	return (ssize_t)size + aroff;
1730 }
1731 
1732 void
1733 dkim_err(struct message *msg, char *text)
1734 {
1735 	msg->err = 1;
1736 	fprintf(stderr, "%s: %s\n", text, strerror(errno));
1737 }
1738 
1739 void
1740 dkim_errx(struct message *msg, char *text)
1741 {
1742 	msg->err = 1;
1743 	fprintf(stderr, "%s\n", text);
1744 }
1745 
1746 __dead void
1747 usage(void)
1748 {
1749 	fprintf(stderr, "usage: filter-dkimverify\n");
1750 	exit(1);
1751 }