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80a47a2c TK |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
d4e5e70b | 5 | /* Copyright (c) University of Cambridge, 1995 - 2017 */ |
80a47a2c TK |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | /* Code for DKIM support. Other DKIM relevant code is in | |
9 | receive.c, transport.c and transports/smtp.c */ | |
10 | ||
11 | #include "exim.h" | |
12 | ||
13 | #ifndef DISABLE_DKIM | |
14 | ||
970424a5 JH |
15 | # include "pdkim/pdkim.h" |
16 | ||
17 | # ifdef MACRO_PREDEF | |
5f69a529 | 18 | # include "macro_predef.h" |
970424a5 JH |
19 | |
20 | void | |
a2701501 | 21 | params_dkim(void) |
970424a5 JH |
22 | { |
23 | builtin_macro_create_var(US"_DKIM_SIGN_HEADERS", US PDKIM_DEFAULT_SIGN_HEADERS); | |
24 | } | |
25 | # else /*!MACRO_PREDEF*/ | |
26 | ||
27 | ||
28 | ||
80a47a2c | 29 | |
ca9cb170 | 30 | int dkim_verify_oldpool; |
1cfe5c1c | 31 | pdkim_ctx *dkim_verify_ctx = NULL; |
80a47a2c | 32 | pdkim_signature *dkim_signatures = NULL; |
1cfe5c1c | 33 | pdkim_signature *dkim_cur_sig = NULL; |
b9df1829 | 34 | static const uschar * dkim_collect_error = NULL; |
80a47a2c | 35 | |
d73e45df JH |
36 | |
37 | ||
38 | /*XXX the caller only uses the first record if we return multiple. | |
39 | Could we hand back an allocated string? | |
40 | */ | |
41 | ||
1cfe5c1c JH |
42 | static int |
43 | dkim_exim_query_dns_txt(char *name, char *answer) | |
44 | { | |
45 | dns_answer dnsa; | |
46 | dns_scan dnss; | |
47 | dns_record *rr; | |
80a47a2c | 48 | |
1cfe5c1c JH |
49 | lookup_dnssec_authenticated = NULL; |
50 | if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED) | |
f7302073 | 51 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
80a47a2c | 52 | |
1cfe5c1c | 53 | /* Search for TXT record */ |
80a47a2c | 54 | |
1cfe5c1c JH |
55 | for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); |
56 | rr; | |
57 | rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT)) | |
58 | if (rr->type == T_TXT) | |
59 | { | |
80a47a2c TK |
60 | int rr_offset = 0; |
61 | int answer_offset = 0; | |
1cfe5c1c JH |
62 | |
63 | /* Copy record content to the answer buffer */ | |
64 | ||
65 | while (rr_offset < rr->size) | |
66 | { | |
67 | uschar len = rr->data[rr_offset++]; | |
68 | snprintf(answer + answer_offset, | |
69 | PDKIM_DNS_TXT_MAX_RECLEN - answer_offset, | |
5903c6ff | 70 | "%.*s", (int)len, CS (rr->data + rr_offset)); |
1cfe5c1c JH |
71 | rr_offset += len; |
72 | answer_offset += len; | |
73 | if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN) | |
f7302073 | 74 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
4263f395 | 75 | } |
1cfe5c1c | 76 | return PDKIM_OK; |
80a47a2c | 77 | } |
80a47a2c | 78 | |
f7302073 | 79 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
80a47a2c TK |
80 | } |
81 | ||
82 | ||
2592e6c0 JH |
83 | void |
84 | dkim_exim_init(void) | |
85 | { | |
86 | pdkim_init(); | |
87 | } | |
88 | ||
89 | ||
ca9cb170 | 90 | |
1cfe5c1c | 91 | void |
e983e85a | 92 | dkim_exim_verify_init(BOOL dot_stuffing) |
1cfe5c1c | 93 | { |
ca9cb170 JH |
94 | /* There is a store-reset between header & body reception |
95 | so cannot use the main pool. Any allocs done by Exim | |
96 | memory-handling must use the perm pool. */ | |
97 | ||
98 | dkim_verify_oldpool = store_pool; | |
99 | store_pool = POOL_PERM; | |
100 | ||
1cfe5c1c | 101 | /* Free previous context if there is one */ |
80a47a2c | 102 | |
1cfe5c1c JH |
103 | if (dkim_verify_ctx) |
104 | pdkim_free_ctx(dkim_verify_ctx); | |
80a47a2c | 105 | |
1cfe5c1c | 106 | /* Create new context */ |
80a47a2c | 107 | |
e983e85a | 108 | dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing); |
3b957582 | 109 | dkim_collect_input = !!dkim_verify_ctx; |
b9df1829 | 110 | dkim_collect_error = NULL; |
ca9cb170 | 111 | |
584e96c6 JH |
112 | /* Start feed up with any cached data */ |
113 | receive_get_cache(); | |
114 | ||
ca9cb170 | 115 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
116 | } |
117 | ||
118 | ||
1cfe5c1c JH |
119 | void |
120 | dkim_exim_verify_feed(uschar * data, int len) | |
121 | { | |
f7302073 JH |
122 | int rc; |
123 | ||
ca9cb170 | 124 | store_pool = POOL_PERM; |
1cfe5c1c | 125 | if ( dkim_collect_input |
ef698bf6 | 126 | && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK) |
f7302073 | 127 | { |
b9df1829 | 128 | dkim_collect_error = pdkim_errstr(rc); |
f7302073 | 129 | log_write(0, LOG_MAIN, |
b9df1829 | 130 | "DKIM: validation error: %.100s", dkim_collect_error); |
1cfe5c1c | 131 | dkim_collect_input = FALSE; |
f7302073 | 132 | } |
ca9cb170 | 133 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
134 | } |
135 | ||
136 | ||
a79d8834 JH |
137 | /* Log the result for the given signature */ |
138 | static void | |
139 | dkim_exim_verify_log_sig(pdkim_signature * sig) | |
1cfe5c1c | 140 | { |
cc55f420 | 141 | gstring * logmsg; |
a79d8834 JH |
142 | uschar * s; |
143 | ||
cc55f420 JH |
144 | if (!sig) return; |
145 | ||
146 | logmsg = string_catn(NULL, "DKIM: ", 6); | |
a79d8834 JH |
147 | if (!(s = sig->domain)) s = US"<UNSET>"; |
148 | logmsg = string_append(logmsg, 2, "d=", s); | |
149 | if (!(s = sig->selector)) s = US"<UNSET>"; | |
150 | logmsg = string_append(logmsg, 2, " s=", s); | |
151 | logmsg = string_append(logmsg, 7, | |
152 | " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", | |
153 | "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", | |
154 | " a=", dkim_sig_to_a_tag(sig), | |
155 | string_sprintf(" b=" SIZE_T_FMT, | |
156 | (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0)); | |
157 | if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s); | |
158 | if (sig->created > 0) logmsg = string_cat(logmsg, | |
159 | string_sprintf(" t=%lu", sig->created)); | |
160 | if (sig->expires > 0) logmsg = string_cat(logmsg, | |
161 | string_sprintf(" x=%lu", sig->expires)); | |
162 | if (sig->bodylength > -1) logmsg = string_cat(logmsg, | |
163 | string_sprintf(" l=%lu", sig->bodylength)); | |
164 | ||
165 | if ( !dkim_verify_status | |
166 | || ( dkim_verify_status == dkim_exim_expand_query(DKIM_VERIFY_STATUS) | |
167 | && dkim_verify_reason == dkim_exim_expand_query(DKIM_VERIFY_REASON) | |
168 | ) ) | |
1cfe5c1c JH |
169 | switch (sig->verify_status) |
170 | { | |
171 | case PDKIM_VERIFY_NONE: | |
acec9514 | 172 | logmsg = string_cat(logmsg, " [not verified]"); |
80a47a2c | 173 | break; |
1cfe5c1c JH |
174 | |
175 | case PDKIM_VERIFY_INVALID: | |
acec9514 | 176 | logmsg = string_cat(logmsg, " [invalid - "); |
1cfe5c1c JH |
177 | switch (sig->verify_ext_status) |
178 | { | |
179 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
acec9514 | 180 | logmsg = string_cat(logmsg, |
a79d8834 | 181 | "public key record (currently?) unavailable]"); |
1cfe5c1c JH |
182 | break; |
183 | ||
184 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: | |
acec9514 | 185 | logmsg = string_cat(logmsg, "overlong public key record]"); |
1cfe5c1c JH |
186 | break; |
187 | ||
df3def24 JH |
188 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: |
189 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: | |
acec9514 | 190 | logmsg = string_cat(logmsg, "syntax error in public key record]"); |
1cfe5c1c | 191 | break; |
07eeb4df | 192 | |
a79d8834 JH |
193 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: |
194 | logmsg = string_cat(logmsg, "signature tag missing or invalid]"); | |
195 | break; | |
07eeb4df | 196 | |
a79d8834 JH |
197 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: |
198 | logmsg = string_cat(logmsg, "unsupported DKIM version]"); | |
199 | break; | |
1cfe5c1c JH |
200 | |
201 | default: | |
acec9514 | 202 | logmsg = string_cat(logmsg, "unspecified problem]"); |
1cfe5c1c | 203 | } |
80a47a2c | 204 | break; |
1cfe5c1c JH |
205 | |
206 | case PDKIM_VERIFY_FAIL: | |
a79d8834 | 207 | logmsg = string_cat(logmsg, " [verification failed - "); |
1cfe5c1c JH |
208 | switch (sig->verify_ext_status) |
209 | { | |
210 | case PDKIM_VERIFY_FAIL_BODY: | |
acec9514 | 211 | logmsg = string_cat(logmsg, |
1cfe5c1c JH |
212 | "body hash mismatch (body probably modified in transit)]"); |
213 | break; | |
214 | ||
215 | case PDKIM_VERIFY_FAIL_MESSAGE: | |
acec9514 | 216 | logmsg = string_cat(logmsg, |
1cfe5c1c JH |
217 | "signature did not verify (headers probably modified in transit)]"); |
218 | break; | |
219 | ||
220 | default: | |
acec9514 | 221 | logmsg = string_cat(logmsg, "unspecified reason]"); |
1cfe5c1c | 222 | } |
80a47a2c | 223 | break; |
1cfe5c1c JH |
224 | |
225 | case PDKIM_VERIFY_PASS: | |
acec9514 | 226 | logmsg = string_cat(logmsg, " [verification succeeded]"); |
80a47a2c TK |
227 | break; |
228 | } | |
a79d8834 JH |
229 | else |
230 | logmsg = string_append(logmsg, 5, | |
231 | US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]"); | |
232 | ||
233 | log_write(0, LOG_MAIN, string_from_gstring(logmsg)); | |
234 | return; | |
235 | } | |
236 | ||
80a47a2c | 237 | |
a79d8834 JH |
238 | /* Log a line for "the current" signature */ |
239 | void | |
240 | dkim_exim_verify_log_item(void) | |
241 | { | |
242 | dkim_exim_verify_log_sig(dkim_cur_sig); | |
243 | } | |
80a47a2c | 244 | |
1cfe5c1c | 245 | |
a79d8834 JH |
246 | /* Log a line for each signature */ |
247 | void | |
248 | dkim_exim_verify_log_all(void) | |
249 | { | |
250 | pdkim_signature * sig; | |
251 | for (sig = dkim_signatures; sig; sig = sig->next) dkim_exim_verify_log_sig(sig); | |
252 | } | |
1cfe5c1c | 253 | |
80a47a2c | 254 | |
a79d8834 JH |
255 | void |
256 | dkim_exim_verify_finish(void) | |
257 | { | |
258 | pdkim_signature * sig; | |
259 | int rc; | |
260 | gstring * g = NULL; | |
261 | const uschar * errstr; | |
262 | ||
263 | store_pool = POOL_PERM; | |
264 | ||
265 | /* Delete eventual previous signature chain */ | |
266 | ||
267 | dkim_signers = NULL; | |
268 | dkim_signatures = NULL; | |
269 | ||
270 | if (dkim_collect_error) | |
271 | { | |
272 | log_write(0, LOG_MAIN, | |
273 | "DKIM: Error during validation, disabling signature verification: %.100s", | |
274 | dkim_collect_error); | |
275 | dkim_disable_verify = TRUE; | |
276 | goto out; | |
277 | } | |
278 | ||
279 | dkim_collect_input = FALSE; | |
280 | ||
281 | /* Finish DKIM operation and fetch link to signatures chain */ | |
282 | ||
283 | rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr); | |
284 | if (rc != PDKIM_OK) | |
285 | { | |
286 | log_write(0, LOG_MAIN, "DKIM: validation error: %.100s%s%s", pdkim_errstr(rc), | |
287 | errstr ? ": " : "", errstr ? errstr : US""); | |
288 | goto out; | |
289 | } | |
290 | ||
291 | /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ | |
292 | ||
293 | for (sig = dkim_signatures; sig; sig = sig->next) | |
294 | { | |
295 | if (sig->domain) g = string_append_listele(g, ':', sig->domain); | |
296 | if (sig->identity) g = string_append_listele(g, ':', sig->identity); | |
80a47a2c TK |
297 | } |
298 | ||
acec9514 JH |
299 | if (g) dkim_signers = g->s; |
300 | ||
ca9cb170 JH |
301 | out: |
302 | store_pool = dkim_verify_oldpool; | |
80a47a2c TK |
303 | } |
304 | ||
305 | ||
1cfe5c1c JH |
306 | void |
307 | dkim_exim_acl_setup(uschar * id) | |
308 | { | |
309 | pdkim_signature * sig; | |
310 | uschar * cmp_val; | |
311 | ||
cc55f420 JH |
312 | dkim_verify_status = US"none"; |
313 | dkim_verify_reason = US""; | |
1cfe5c1c JH |
314 | dkim_cur_sig = NULL; |
315 | dkim_cur_signer = id; | |
316 | ||
317 | if (dkim_disable_verify || !id || !dkim_verify_ctx) | |
318 | return; | |
319 | ||
320 | /* Find signature to run ACL on */ | |
321 | ||
322 | for (sig = dkim_signatures; sig; sig = sig->next) | |
323 | if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain) | |
324 | && strcmpic(cmp_val, id) == 0 | |
325 | ) | |
326 | { | |
327 | dkim_cur_sig = sig; | |
328 | ||
329 | /* The "dkim_domain" and "dkim_selector" expansion variables have | |
330 | related globals, since they are used in the signing code too. | |
331 | Instead of inventing separate names for verification, we set | |
332 | them here. This is easy since a domain and selector is guaranteed | |
333 | to be in a signature. The other dkim_* expansion items are | |
334 | dynamically fetched from dkim_cur_sig at expansion time (see | |
335 | function below). */ | |
336 | ||
337 | dkim_signing_domain = US sig->domain; | |
338 | dkim_signing_selector = US sig->selector; | |
dcd03763 | 339 | dkim_key_length = sig->sighash.len * 8; |
a79d8834 JH |
340 | |
341 | /* These two return static strings, so we can compare the addr | |
342 | later to see if the ACL overwrote them. Check that when logging */ | |
343 | ||
344 | dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS); | |
345 | dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON); | |
1cfe5c1c | 346 | return; |
80a47a2c | 347 | } |
80a47a2c TK |
348 | } |
349 | ||
350 | ||
1cfe5c1c JH |
351 | static uschar * |
352 | dkim_exim_expand_defaults(int what) | |
353 | { | |
354 | switch (what) | |
355 | { | |
356 | case DKIM_ALGO: return US""; | |
357 | case DKIM_BODYLENGTH: return US"9999999999999"; | |
358 | case DKIM_CANON_BODY: return US""; | |
359 | case DKIM_CANON_HEADERS: return US""; | |
360 | case DKIM_COPIEDHEADERS: return US""; | |
361 | case DKIM_CREATED: return US"0"; | |
362 | case DKIM_EXPIRES: return US"9999999999999"; | |
363 | case DKIM_HEADERNAMES: return US""; | |
364 | case DKIM_IDENTITY: return US""; | |
365 | case DKIM_KEY_GRANULARITY: return US"*"; | |
366 | case DKIM_KEY_SRVTYPE: return US"*"; | |
367 | case DKIM_KEY_NOTES: return US""; | |
368 | case DKIM_KEY_TESTING: return US"0"; | |
369 | case DKIM_NOSUBDOMAINS: return US"0"; | |
370 | case DKIM_VERIFY_STATUS: return US"none"; | |
371 | case DKIM_VERIFY_REASON: return US""; | |
372 | default: return US""; | |
373 | } | |
374 | } | |
80a47a2c | 375 | |
80a47a2c | 376 | |
1cfe5c1c JH |
377 | uschar * |
378 | dkim_exim_expand_query(int what) | |
379 | { | |
380 | if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig) | |
381 | return dkim_exim_expand_defaults(what); | |
382 | ||
383 | switch (what) | |
384 | { | |
385 | case DKIM_ALGO: | |
d73e45df | 386 | return dkim_sig_to_a_tag(dkim_cur_sig); |
1cfe5c1c JH |
387 | |
388 | case DKIM_BODYLENGTH: | |
389 | return dkim_cur_sig->bodylength >= 0 | |
bb07bcd3 | 390 | ? string_sprintf("%ld", dkim_cur_sig->bodylength) |
1cfe5c1c JH |
391 | : dkim_exim_expand_defaults(what); |
392 | ||
393 | case DKIM_CANON_BODY: | |
394 | switch (dkim_cur_sig->canon_body) | |
395 | { | |
396 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
397 | case PDKIM_CANON_SIMPLE: | |
398 | default: return US"simple"; | |
80a47a2c | 399 | } |
1cfe5c1c JH |
400 | |
401 | case DKIM_CANON_HEADERS: | |
a79d8834 JH |
402 | switch (dkim_cur_sig->canon_headers) |
403 | { | |
404 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
405 | case PDKIM_CANON_SIMPLE: | |
406 | default: return US"simple"; | |
407 | } | |
1cfe5c1c JH |
408 | |
409 | case DKIM_COPIEDHEADERS: | |
410 | return dkim_cur_sig->copiedheaders | |
411 | ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what); | |
412 | ||
413 | case DKIM_CREATED: | |
414 | return dkim_cur_sig->created > 0 | |
bb07bcd3 | 415 | ? string_sprintf("%lu", dkim_cur_sig->created) |
1cfe5c1c JH |
416 | : dkim_exim_expand_defaults(what); |
417 | ||
418 | case DKIM_EXPIRES: | |
419 | return dkim_cur_sig->expires > 0 | |
bb07bcd3 | 420 | ? string_sprintf("%lu", dkim_cur_sig->expires) |
1cfe5c1c JH |
421 | : dkim_exim_expand_defaults(what); |
422 | ||
423 | case DKIM_HEADERNAMES: | |
424 | return dkim_cur_sig->headernames | |
2592e6c0 | 425 | ? dkim_cur_sig->headernames : dkim_exim_expand_defaults(what); |
1cfe5c1c JH |
426 | |
427 | case DKIM_IDENTITY: | |
428 | return dkim_cur_sig->identity | |
429 | ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what); | |
430 | ||
431 | case DKIM_KEY_GRANULARITY: | |
432 | return dkim_cur_sig->pubkey | |
433 | ? dkim_cur_sig->pubkey->granularity | |
434 | ? US dkim_cur_sig->pubkey->granularity | |
435 | : dkim_exim_expand_defaults(what) | |
436 | : dkim_exim_expand_defaults(what); | |
437 | ||
438 | case DKIM_KEY_SRVTYPE: | |
439 | return dkim_cur_sig->pubkey | |
440 | ? dkim_cur_sig->pubkey->srvtype | |
441 | ? US dkim_cur_sig->pubkey->srvtype | |
442 | : dkim_exim_expand_defaults(what) | |
443 | : dkim_exim_expand_defaults(what); | |
444 | ||
445 | case DKIM_KEY_NOTES: | |
446 | return dkim_cur_sig->pubkey | |
447 | ? dkim_cur_sig->pubkey->notes | |
448 | ? US dkim_cur_sig->pubkey->notes | |
449 | : dkim_exim_expand_defaults(what) | |
450 | : dkim_exim_expand_defaults(what); | |
451 | ||
452 | case DKIM_KEY_TESTING: | |
453 | return dkim_cur_sig->pubkey | |
454 | ? dkim_cur_sig->pubkey->testing | |
455 | ? US"1" | |
456 | : dkim_exim_expand_defaults(what) | |
457 | : dkim_exim_expand_defaults(what); | |
458 | ||
459 | case DKIM_NOSUBDOMAINS: | |
460 | return dkim_cur_sig->pubkey | |
461 | ? dkim_cur_sig->pubkey->no_subdomaining | |
462 | ? US"1" | |
463 | : dkim_exim_expand_defaults(what) | |
464 | : dkim_exim_expand_defaults(what); | |
465 | ||
466 | case DKIM_VERIFY_STATUS: | |
467 | switch (dkim_cur_sig->verify_status) | |
468 | { | |
469 | case PDKIM_VERIFY_INVALID: return US"invalid"; | |
470 | case PDKIM_VERIFY_FAIL: return US"fail"; | |
471 | case PDKIM_VERIFY_PASS: return US"pass"; | |
472 | case PDKIM_VERIFY_NONE: | |
473 | default: return US"none"; | |
80a47a2c | 474 | } |
80a47a2c | 475 | |
1cfe5c1c JH |
476 | case DKIM_VERIFY_REASON: |
477 | switch (dkim_cur_sig->verify_ext_status) | |
478 | { | |
479 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
480 | return US"pubkey_unavailable"; | |
df3def24 JH |
481 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax"; |
482 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax"; | |
1cfe5c1c JH |
483 | case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch"; |
484 | case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect"; | |
485 | } | |
80a47a2c | 486 | |
1cfe5c1c JH |
487 | default: |
488 | return US""; | |
80a47a2c TK |
489 | } |
490 | } | |
491 | ||
492 | ||
42055a33 JH |
493 | /* Generate signatures for the given file, returning a string. |
494 | If a prefix is given, prepend it to the file for the calculations. | |
495 | */ | |
496 | ||
acec9514 | 497 | gstring * |
42055a33 JH |
498 | dkim_exim_sign(int fd, off_t off, uschar * prefix, |
499 | struct ob_dkim * dkim, const uschar ** errstr) | |
55414b25 | 500 | { |
e983e85a | 501 | const uschar * dkim_domain; |
1cfe5c1c | 502 | int sep = 0; |
acec9514 | 503 | gstring * seen_doms = NULL; |
9e70917d JH |
504 | pdkim_ctx ctx; |
505 | pdkim_signature * sig; | |
acec9514 | 506 | gstring * sigbuf; |
1cfe5c1c JH |
507 | int pdkim_rc; |
508 | int sread; | |
ef698bf6 | 509 | uschar buf[4096]; |
1cfe5c1c JH |
510 | int save_errno = 0; |
511 | int old_pool = store_pool; | |
7c6ec81b | 512 | uschar * errwhen; |
1cfe5c1c JH |
513 | |
514 | store_pool = POOL_MAIN; | |
515 | ||
9e70917d JH |
516 | pdkim_init_context(&ctx, dkim->dot_stuffed, &dkim_exim_query_dns_txt); |
517 | ||
e983e85a | 518 | if (!(dkim_domain = expand_cstring(dkim->dkim_domain))) |
1cfe5c1c | 519 | /* expansion error, do not send message. */ |
7c6ec81b | 520 | { errwhen = US"dkim_domain"; goto expand_bad; } |
1cfe5c1c JH |
521 | |
522 | /* Set $dkim_domain expansion variable to each unique domain in list. */ | |
523 | ||
42055a33 | 524 | while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) |
1cfe5c1c | 525 | { |
9e70917d JH |
526 | const uschar * dkim_sel; |
527 | int sel_sep = 0; | |
528 | ||
42055a33 | 529 | if (dkim_signing_domain[0] == '\0') |
1cfe5c1c JH |
530 | continue; |
531 | ||
532 | /* Only sign once for each domain, no matter how often it | |
533 | appears in the expanded list. */ | |
534 | ||
9e70917d JH |
535 | if (match_isinlist(dkim_signing_domain, CUSS &seen_doms, |
536 | 0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK) | |
537 | continue; | |
1cfe5c1c | 538 | |
acec9514 | 539 | seen_doms = string_append_listele(seen_doms, ':', dkim_signing_domain); |
1cfe5c1c | 540 | |
9e70917d JH |
541 | /* Set $dkim_selector expansion variable to each selector in list, |
542 | for this domain. */ | |
1cfe5c1c | 543 | |
9e70917d | 544 | if (!(dkim_sel = expand_string(dkim->dkim_selector))) |
e983e85a | 545 | if (!(dkim_signing_selector = expand_string(dkim->dkim_selector))) |
7c6ec81b | 546 | { errwhen = US"dkim_selector"; goto expand_bad; } |
1cfe5c1c | 547 | |
9e70917d JH |
548 | while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep, |
549 | NULL, 0))) | |
1cfe5c1c | 550 | { |
9e70917d JH |
551 | uschar * dkim_canon_expanded; |
552 | int pdkim_canon; | |
553 | uschar * dkim_sign_headers_expanded = NULL; | |
554 | uschar * dkim_private_key_expanded; | |
555 | uschar * dkim_hash_expanded; | |
7c6ec81b | 556 | uschar * dkim_identity_expanded = NULL; |
80a47a2c | 557 | |
9e70917d | 558 | /* Get canonicalization to use */ |
1cfe5c1c | 559 | |
9e70917d JH |
560 | dkim_canon_expanded = dkim->dkim_canon |
561 | ? expand_string(dkim->dkim_canon) : US"relaxed"; | |
7c6ec81b JH |
562 | if (!dkim_canon_expanded) /* expansion error, do not send message. */ |
563 | { errwhen = US"dkim_canon"; goto expand_bad; } | |
1cfe5c1c | 564 | |
9e70917d JH |
565 | if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) |
566 | pdkim_canon = PDKIM_CANON_RELAXED; | |
567 | else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) | |
568 | pdkim_canon = PDKIM_CANON_SIMPLE; | |
569 | else | |
570 | { | |
571 | log_write(0, LOG_MAIN, | |
572 | "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", | |
573 | dkim_canon_expanded); | |
574 | pdkim_canon = PDKIM_CANON_RELAXED; | |
575 | } | |
1cfe5c1c | 576 | |
7c6ec81b JH |
577 | if ( dkim->dkim_sign_headers |
578 | && !(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) | |
579 | { errwhen = US"dkim_sign_header"; goto expand_bad; } | |
580 | /* else pass NULL, which means default header list */ | |
1cfe5c1c | 581 | |
9e70917d | 582 | /* Get private key to use. */ |
e983e85a | 583 | |
9e70917d | 584 | if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) |
7c6ec81b | 585 | { errwhen = US"dkim_private_key"; goto expand_bad; } |
80a47a2c | 586 | |
9e70917d JH |
587 | if ( Ustrlen(dkim_private_key_expanded) == 0 |
588 | || Ustrcmp(dkim_private_key_expanded, "0") == 0 | |
589 | || Ustrcmp(dkim_private_key_expanded, "false") == 0 | |
590 | ) | |
591 | continue; /* don't sign, but no error */ | |
592 | ||
593 | if (dkim_private_key_expanded[0] == '/') | |
1cfe5c1c | 594 | { |
9e70917d JH |
595 | int privkey_fd, off = 0, len; |
596 | ||
597 | /* Looks like a filename, load the private key. */ | |
598 | ||
599 | memset(big_buffer, 0, big_buffer_size); | |
600 | ||
601 | if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0) | |
59d98039 | 602 | { |
9e70917d JH |
603 | log_write(0, LOG_MAIN | LOG_PANIC, "unable to open " |
604 | "private key file for reading: %s", | |
59d98039 JH |
605 | dkim_private_key_expanded); |
606 | goto bad; | |
607 | } | |
9e70917d JH |
608 | |
609 | do | |
610 | { | |
611 | if ((len = read(privkey_fd, big_buffer + off, big_buffer_size - 2 - off)) < 0) | |
612 | { | |
613 | (void) close(privkey_fd); | |
614 | log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s", | |
615 | dkim_private_key_expanded); | |
616 | goto bad; | |
617 | } | |
618 | off += len; | |
619 | } | |
620 | while (len > 0); | |
621 | ||
622 | (void) close(privkey_fd); | |
623 | big_buffer[off] = '\0'; | |
624 | dkim_private_key_expanded = big_buffer; | |
1ac6b2e7 | 625 | } |
80a47a2c | 626 | |
9e70917d | 627 | if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash))) |
7c6ec81b JH |
628 | { errwhen = US"dkim_hash"; goto expand_bad; } |
629 | ||
630 | if (dkim->dkim_identity) | |
631 | if (!(dkim_identity_expanded = expand_string(dkim->dkim_identity))) | |
632 | { errwhen = US"dkim_identity"; goto expand_bad; } | |
633 | else if (!*dkim_identity_expanded) | |
634 | dkim_identity_expanded = NULL; | |
1cfe5c1c | 635 | |
9e70917d JH |
636 | /*XXX so we currently nail signing to RSA + this hash. |
637 | Need to extract algo from privkey and check for disallowed combos. */ | |
d73e45df | 638 | |
9e70917d JH |
639 | if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain, |
640 | dkim_signing_selector, | |
641 | dkim_private_key_expanded, | |
642 | dkim_hash_expanded, | |
643 | errstr | |
644 | ))) | |
645 | goto bad; | |
646 | dkim_private_key_expanded[0] = '\0'; | |
647 | ||
648 | pdkim_set_optional(sig, | |
649 | CS dkim_sign_headers_expanded, | |
7c6ec81b | 650 | dkim_identity_expanded, |
9e70917d JH |
651 | pdkim_canon, |
652 | pdkim_canon, -1, 0, 0); | |
653 | ||
654 | if (!ctx.sig) /* link sig to context chain */ | |
655 | ctx.sig = sig; | |
656 | else | |
657 | { | |
658 | pdkim_signature * n = ctx.sig; | |
659 | while (n->next) n = n->next; | |
660 | n->next = sig; | |
661 | } | |
80a47a2c | 662 | } |
9e70917d | 663 | } |
80a47a2c | 664 | |
9e70917d JH |
665 | if (prefix) |
666 | pdkim_feed(&ctx, prefix, Ustrlen(prefix)); | |
80a47a2c | 667 | |
9e70917d JH |
668 | if (lseek(fd, off, SEEK_SET) < 0) |
669 | sread = -1; | |
670 | else | |
671 | while ((sread = read(fd, &buf, sizeof(buf))) > 0) | |
672 | if ((pdkim_rc = pdkim_feed(&ctx, buf, sread)) != PDKIM_OK) | |
673 | goto pk_bad; | |
80a47a2c | 674 | |
9e70917d JH |
675 | /* Handle failed read above. */ |
676 | if (sread == -1) | |
677 | { | |
678 | debug_printf("DKIM: Error reading -K file.\n"); | |
679 | save_errno = errno; | |
680 | goto bad; | |
80a47a2c | 681 | } |
a8e1eeba | 682 | |
9e70917d JH |
683 | /* Build string of headers, one per signature */ |
684 | ||
685 | if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK) | |
686 | goto pk_bad; | |
687 | ||
acec9514 JH |
688 | for (sigbuf = NULL; sig; sig = sig->next) |
689 | sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n"); | |
9e70917d | 690 | |
acec9514 | 691 | (void) string_from_gstring(sigbuf); |
1cfe5c1c JH |
692 | |
693 | CLEANUP: | |
f7302073 JH |
694 | store_pool = old_pool; |
695 | errno = save_errno; | |
9e70917d | 696 | return sigbuf; |
f7302073 JH |
697 | |
698 | pk_bad: | |
699 | log_write(0, LOG_MAIN|LOG_PANIC, | |
700 | "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc)); | |
701 | bad: | |
9e70917d | 702 | sigbuf = NULL; |
f7302073 | 703 | goto CLEANUP; |
7c6ec81b JH |
704 | |
705 | expand_bad: | |
706 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand %s: %s", | |
707 | errwhen, expand_string_message); | |
708 | goto bad; | |
93f2d376 | 709 | } |
80a47a2c | 710 | |
970424a5 JH |
711 | # endif /*!MACRO_PREDEF*/ |
712 | #endif /*!DISABLE_DKIM*/ |