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