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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 | } |
dd33c4e6 HSHR |
76 | |
77 | /* check if this looks like a DKIM record */ | |
78 | if (strncasecmp(answer, "v=dkim", 6) != 0) continue; | |
1cfe5c1c | 79 | return PDKIM_OK; |
80a47a2c | 80 | } |
80a47a2c | 81 | |
f7302073 | 82 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
80a47a2c TK |
83 | } |
84 | ||
85 | ||
2592e6c0 JH |
86 | void |
87 | dkim_exim_init(void) | |
88 | { | |
89 | pdkim_init(); | |
90 | } | |
91 | ||
92 | ||
ca9cb170 | 93 | |
1cfe5c1c | 94 | void |
e983e85a | 95 | dkim_exim_verify_init(BOOL dot_stuffing) |
1cfe5c1c | 96 | { |
ca9cb170 JH |
97 | /* There is a store-reset between header & body reception |
98 | so cannot use the main pool. Any allocs done by Exim | |
99 | memory-handling must use the perm pool. */ | |
100 | ||
101 | dkim_verify_oldpool = store_pool; | |
102 | store_pool = POOL_PERM; | |
103 | ||
1cfe5c1c | 104 | /* Free previous context if there is one */ |
80a47a2c | 105 | |
1cfe5c1c JH |
106 | if (dkim_verify_ctx) |
107 | pdkim_free_ctx(dkim_verify_ctx); | |
80a47a2c | 108 | |
1cfe5c1c | 109 | /* Create new context */ |
80a47a2c | 110 | |
e983e85a | 111 | dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing); |
3b957582 | 112 | dkim_collect_input = !!dkim_verify_ctx; |
b9df1829 | 113 | dkim_collect_error = NULL; |
ca9cb170 | 114 | |
584e96c6 JH |
115 | /* Start feed up with any cached data */ |
116 | receive_get_cache(); | |
117 | ||
ca9cb170 | 118 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
119 | } |
120 | ||
121 | ||
1cfe5c1c JH |
122 | void |
123 | dkim_exim_verify_feed(uschar * data, int len) | |
124 | { | |
f7302073 JH |
125 | int rc; |
126 | ||
ca9cb170 | 127 | store_pool = POOL_PERM; |
1cfe5c1c | 128 | if ( dkim_collect_input |
ef698bf6 | 129 | && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK) |
f7302073 | 130 | { |
b9df1829 | 131 | dkim_collect_error = pdkim_errstr(rc); |
f7302073 | 132 | log_write(0, LOG_MAIN, |
b9df1829 | 133 | "DKIM: validation error: %.100s", dkim_collect_error); |
1cfe5c1c | 134 | dkim_collect_input = FALSE; |
f7302073 | 135 | } |
ca9cb170 | 136 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
137 | } |
138 | ||
139 | ||
a79d8834 JH |
140 | /* Log the result for the given signature */ |
141 | static void | |
142 | dkim_exim_verify_log_sig(pdkim_signature * sig) | |
1cfe5c1c | 143 | { |
cc55f420 | 144 | gstring * logmsg; |
a79d8834 JH |
145 | uschar * s; |
146 | ||
cc55f420 JH |
147 | if (!sig) return; |
148 | ||
2c47372f JH |
149 | if ( !dkim_verify_overall |
150 | && dkim_verify_status | |
151 | ? Ustrcmp(dkim_verify_status, US"pass") == 0 | |
152 | : sig->verify_status == PDKIM_VERIFY_PASS | |
153 | ) | |
154 | dkim_verify_overall = string_copy(sig->domain); | |
155 | ||
156 | if (!LOGGING(dkim_verbose)) return; | |
157 | ||
aaaa94ea | 158 | logmsg = string_catn(NULL, US"DKIM: ", 6); |
a79d8834 JH |
159 | if (!(s = sig->domain)) s = US"<UNSET>"; |
160 | logmsg = string_append(logmsg, 2, "d=", s); | |
161 | if (!(s = sig->selector)) s = US"<UNSET>"; | |
162 | logmsg = string_append(logmsg, 2, " s=", s); | |
dd33c4e6 | 163 | logmsg = string_append(logmsg, 7, |
a79d8834 JH |
164 | " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", |
165 | "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", | |
166 | " a=", dkim_sig_to_a_tag(sig), | |
167 | string_sprintf(" b=" SIZE_T_FMT, | |
168 | (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0)); | |
169 | if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s); | |
170 | if (sig->created > 0) logmsg = string_cat(logmsg, | |
171 | string_sprintf(" t=%lu", sig->created)); | |
172 | if (sig->expires > 0) logmsg = string_cat(logmsg, | |
173 | string_sprintf(" x=%lu", sig->expires)); | |
174 | if (sig->bodylength > -1) logmsg = string_cat(logmsg, | |
175 | string_sprintf(" l=%lu", sig->bodylength)); | |
176 | ||
177 | if ( !dkim_verify_status | |
178 | || ( dkim_verify_status == dkim_exim_expand_query(DKIM_VERIFY_STATUS) | |
179 | && dkim_verify_reason == dkim_exim_expand_query(DKIM_VERIFY_REASON) | |
180 | ) ) | |
1cfe5c1c JH |
181 | switch (sig->verify_status) |
182 | { | |
183 | case PDKIM_VERIFY_NONE: | |
aaaa94ea | 184 | logmsg = string_cat(logmsg, US" [not verified]"); |
80a47a2c | 185 | break; |
1cfe5c1c JH |
186 | |
187 | case PDKIM_VERIFY_INVALID: | |
aaaa94ea | 188 | logmsg = string_cat(logmsg, US" [invalid - "); |
1cfe5c1c JH |
189 | switch (sig->verify_ext_status) |
190 | { | |
191 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
acec9514 | 192 | logmsg = string_cat(logmsg, |
aaaa94ea | 193 | US"public key record (currently?) unavailable]"); |
1cfe5c1c JH |
194 | break; |
195 | ||
196 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: | |
aaaa94ea | 197 | logmsg = string_cat(logmsg, US"overlong public key record]"); |
1cfe5c1c JH |
198 | break; |
199 | ||
df3def24 JH |
200 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: |
201 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: | |
aaaa94ea | 202 | logmsg = string_cat(logmsg, US"syntax error in public key record]"); |
1cfe5c1c | 203 | break; |
07eeb4df | 204 | |
a79d8834 | 205 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: |
aaaa94ea | 206 | logmsg = string_cat(logmsg, US"signature tag missing or invalid]"); |
a79d8834 | 207 | break; |
07eeb4df | 208 | |
a79d8834 | 209 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: |
aaaa94ea | 210 | logmsg = string_cat(logmsg, US"unsupported DKIM version]"); |
a79d8834 | 211 | break; |
1cfe5c1c JH |
212 | |
213 | default: | |
aaaa94ea | 214 | logmsg = string_cat(logmsg, US"unspecified problem]"); |
1cfe5c1c | 215 | } |
80a47a2c | 216 | break; |
1cfe5c1c JH |
217 | |
218 | case PDKIM_VERIFY_FAIL: | |
aaaa94ea | 219 | logmsg = string_cat(logmsg, US" [verification failed - "); |
1cfe5c1c JH |
220 | switch (sig->verify_ext_status) |
221 | { | |
222 | case PDKIM_VERIFY_FAIL_BODY: | |
acec9514 | 223 | logmsg = string_cat(logmsg, |
aaaa94ea | 224 | US"body hash mismatch (body probably modified in transit)]"); |
1cfe5c1c JH |
225 | break; |
226 | ||
227 | case PDKIM_VERIFY_FAIL_MESSAGE: | |
acec9514 | 228 | logmsg = string_cat(logmsg, |
aaaa94ea JH |
229 | US"signature did not verify " |
230 | "(headers probably modified in transit)]"); | |
1cfe5c1c JH |
231 | break; |
232 | ||
233 | default: | |
aaaa94ea | 234 | logmsg = string_cat(logmsg, US"unspecified reason]"); |
1cfe5c1c | 235 | } |
80a47a2c | 236 | break; |
1cfe5c1c JH |
237 | |
238 | case PDKIM_VERIFY_PASS: | |
aaaa94ea | 239 | logmsg = string_cat(logmsg, US" [verification succeeded]"); |
80a47a2c TK |
240 | break; |
241 | } | |
a79d8834 JH |
242 | else |
243 | logmsg = string_append(logmsg, 5, | |
244 | US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]"); | |
245 | ||
aaaa94ea | 246 | log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg)); |
a79d8834 JH |
247 | return; |
248 | } | |
249 | ||
80a47a2c | 250 | |
a79d8834 JH |
251 | /* Log a line for each signature */ |
252 | void | |
253 | dkim_exim_verify_log_all(void) | |
254 | { | |
255 | pdkim_signature * sig; | |
256 | for (sig = dkim_signatures; sig; sig = sig->next) dkim_exim_verify_log_sig(sig); | |
257 | } | |
1cfe5c1c | 258 | |
80a47a2c | 259 | |
a79d8834 JH |
260 | void |
261 | dkim_exim_verify_finish(void) | |
262 | { | |
263 | pdkim_signature * sig; | |
264 | int rc; | |
265 | gstring * g = NULL; | |
266 | const uschar * errstr; | |
267 | ||
268 | store_pool = POOL_PERM; | |
269 | ||
270 | /* Delete eventual previous signature chain */ | |
271 | ||
272 | dkim_signers = NULL; | |
273 | dkim_signatures = NULL; | |
274 | ||
275 | if (dkim_collect_error) | |
276 | { | |
277 | log_write(0, LOG_MAIN, | |
278 | "DKIM: Error during validation, disabling signature verification: %.100s", | |
279 | dkim_collect_error); | |
280 | dkim_disable_verify = TRUE; | |
281 | goto out; | |
282 | } | |
283 | ||
284 | dkim_collect_input = FALSE; | |
285 | ||
286 | /* Finish DKIM operation and fetch link to signatures chain */ | |
287 | ||
288 | rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr); | |
289 | if (rc != PDKIM_OK) | |
290 | { | |
291 | log_write(0, LOG_MAIN, "DKIM: validation error: %.100s%s%s", pdkim_errstr(rc), | |
292 | errstr ? ": " : "", errstr ? errstr : US""); | |
293 | goto out; | |
294 | } | |
295 | ||
296 | /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ | |
297 | ||
298 | for (sig = dkim_signatures; sig; sig = sig->next) | |
299 | { | |
300 | if (sig->domain) g = string_append_listele(g, ':', sig->domain); | |
301 | if (sig->identity) g = string_append_listele(g, ':', sig->identity); | |
80a47a2c TK |
302 | } |
303 | ||
acec9514 JH |
304 | if (g) dkim_signers = g->s; |
305 | ||
ca9cb170 JH |
306 | out: |
307 | store_pool = dkim_verify_oldpool; | |
80a47a2c TK |
308 | } |
309 | ||
310 | ||
18067c75 JH |
311 | |
312 | /* Args as per dkim_exim_acl_run() below */ | |
313 | static int | |
314 | dkim_acl_call(uschar * id, gstring ** res_ptr, | |
315 | uschar ** user_msgptr, uschar ** log_msgptr) | |
316 | { | |
317 | int rc; | |
318 | DEBUG(D_receive) | |
319 | debug_printf("calling acl_smtp_dkim for dkim_cur_signer='%s'\n", id); | |
320 | ||
321 | rc = acl_check(ACL_WHERE_DKIM, NULL, acl_smtp_dkim, user_msgptr, log_msgptr); | |
322 | dkim_exim_verify_log_sig(dkim_cur_sig); | |
323 | *res_ptr = string_append_listele(*res_ptr, ':', dkim_verify_status); | |
324 | return rc; | |
325 | } | |
326 | ||
327 | ||
328 | ||
329 | /* For the given identity, run the DKIM ACL once for each matching signature. | |
330 | ||
331 | Arguments | |
332 | id Identity to look for in dkim signatures | |
333 | res_ptr ptr to growable string-list of status results, | |
334 | appended to per ACL run | |
335 | user_msgptr where to put a user error (for SMTP response) | |
336 | log_msgptr where to put a logging message (not for SMTP response) | |
337 | ||
338 | Returns: OK access is granted by an ACCEPT verb | |
339 | DISCARD access is granted by a DISCARD verb | |
340 | FAIL access is denied | |
341 | FAIL_DROP access is denied; drop the connection | |
342 | DEFER can't tell at the moment | |
343 | ERROR disaster | |
344 | */ | |
345 | ||
346 | int | |
347 | dkim_exim_acl_run(uschar * id, gstring ** res_ptr, | |
348 | uschar ** user_msgptr, uschar ** log_msgptr) | |
1cfe5c1c JH |
349 | { |
350 | pdkim_signature * sig; | |
351 | uschar * cmp_val; | |
18067c75 | 352 | int rc = -1; |
1cfe5c1c | 353 | |
cc55f420 JH |
354 | dkim_verify_status = US"none"; |
355 | dkim_verify_reason = US""; | |
1cfe5c1c JH |
356 | dkim_cur_signer = id; |
357 | ||
358 | if (dkim_disable_verify || !id || !dkim_verify_ctx) | |
18067c75 | 359 | return OK; |
1cfe5c1c | 360 | |
18067c75 | 361 | /* Find signatures to run ACL on */ |
1cfe5c1c JH |
362 | |
363 | for (sig = dkim_signatures; sig; sig = sig->next) | |
364 | if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain) | |
365 | && strcmpic(cmp_val, id) == 0 | |
366 | ) | |
367 | { | |
1cfe5c1c | 368 | /* The "dkim_domain" and "dkim_selector" expansion variables have |
18067c75 JH |
369 | related globals, since they are used in the signing code too. |
370 | Instead of inventing separate names for verification, we set | |
371 | them here. This is easy since a domain and selector is guaranteed | |
372 | to be in a signature. The other dkim_* expansion items are | |
373 | dynamically fetched from dkim_cur_sig at expansion time (see | |
374 | function below). */ | |
1cfe5c1c | 375 | |
18067c75 | 376 | dkim_cur_sig = sig; |
1cfe5c1c JH |
377 | dkim_signing_domain = US sig->domain; |
378 | dkim_signing_selector = US sig->selector; | |
dcd03763 | 379 | dkim_key_length = sig->sighash.len * 8; |
a79d8834 JH |
380 | |
381 | /* These two return static strings, so we can compare the addr | |
382 | later to see if the ACL overwrote them. Check that when logging */ | |
383 | ||
384 | dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS); | |
385 | dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON); | |
dd33c4e6 | 386 | |
18067c75 JH |
387 | if ((rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK) |
388 | return rc; | |
80a47a2c | 389 | } |
18067c75 JH |
390 | |
391 | if (rc != -1) | |
392 | return rc; | |
393 | ||
394 | /* No matching sig found. Call ACL once anyway. */ | |
395 | ||
396 | dkim_cur_sig = NULL; | |
397 | return dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr); | |
80a47a2c TK |
398 | } |
399 | ||
400 | ||
1cfe5c1c JH |
401 | static uschar * |
402 | dkim_exim_expand_defaults(int what) | |
403 | { | |
404 | switch (what) | |
405 | { | |
406 | case DKIM_ALGO: return US""; | |
407 | case DKIM_BODYLENGTH: return US"9999999999999"; | |
408 | case DKIM_CANON_BODY: return US""; | |
409 | case DKIM_CANON_HEADERS: return US""; | |
410 | case DKIM_COPIEDHEADERS: return US""; | |
411 | case DKIM_CREATED: return US"0"; | |
412 | case DKIM_EXPIRES: return US"9999999999999"; | |
413 | case DKIM_HEADERNAMES: return US""; | |
414 | case DKIM_IDENTITY: return US""; | |
415 | case DKIM_KEY_GRANULARITY: return US"*"; | |
416 | case DKIM_KEY_SRVTYPE: return US"*"; | |
417 | case DKIM_KEY_NOTES: return US""; | |
418 | case DKIM_KEY_TESTING: return US"0"; | |
419 | case DKIM_NOSUBDOMAINS: return US"0"; | |
420 | case DKIM_VERIFY_STATUS: return US"none"; | |
421 | case DKIM_VERIFY_REASON: return US""; | |
422 | default: return US""; | |
423 | } | |
424 | } | |
80a47a2c | 425 | |
80a47a2c | 426 | |
1cfe5c1c JH |
427 | uschar * |
428 | dkim_exim_expand_query(int what) | |
429 | { | |
430 | if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig) | |
431 | return dkim_exim_expand_defaults(what); | |
432 | ||
433 | switch (what) | |
434 | { | |
435 | case DKIM_ALGO: | |
d73e45df | 436 | return dkim_sig_to_a_tag(dkim_cur_sig); |
1cfe5c1c JH |
437 | |
438 | case DKIM_BODYLENGTH: | |
439 | return dkim_cur_sig->bodylength >= 0 | |
bb07bcd3 | 440 | ? string_sprintf("%ld", dkim_cur_sig->bodylength) |
1cfe5c1c JH |
441 | : dkim_exim_expand_defaults(what); |
442 | ||
443 | case DKIM_CANON_BODY: | |
444 | switch (dkim_cur_sig->canon_body) | |
445 | { | |
446 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
447 | case PDKIM_CANON_SIMPLE: | |
448 | default: return US"simple"; | |
80a47a2c | 449 | } |
1cfe5c1c JH |
450 | |
451 | case DKIM_CANON_HEADERS: | |
a79d8834 JH |
452 | switch (dkim_cur_sig->canon_headers) |
453 | { | |
454 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
455 | case PDKIM_CANON_SIMPLE: | |
456 | default: return US"simple"; | |
457 | } | |
1cfe5c1c JH |
458 | |
459 | case DKIM_COPIEDHEADERS: | |
460 | return dkim_cur_sig->copiedheaders | |
461 | ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what); | |
462 | ||
463 | case DKIM_CREATED: | |
464 | return dkim_cur_sig->created > 0 | |
bb07bcd3 | 465 | ? string_sprintf("%lu", dkim_cur_sig->created) |
1cfe5c1c JH |
466 | : dkim_exim_expand_defaults(what); |
467 | ||
468 | case DKIM_EXPIRES: | |
469 | return dkim_cur_sig->expires > 0 | |
bb07bcd3 | 470 | ? string_sprintf("%lu", dkim_cur_sig->expires) |
1cfe5c1c JH |
471 | : dkim_exim_expand_defaults(what); |
472 | ||
473 | case DKIM_HEADERNAMES: | |
474 | return dkim_cur_sig->headernames | |
2592e6c0 | 475 | ? dkim_cur_sig->headernames : dkim_exim_expand_defaults(what); |
1cfe5c1c JH |
476 | |
477 | case DKIM_IDENTITY: | |
478 | return dkim_cur_sig->identity | |
479 | ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what); | |
480 | ||
481 | case DKIM_KEY_GRANULARITY: | |
482 | return dkim_cur_sig->pubkey | |
483 | ? dkim_cur_sig->pubkey->granularity | |
484 | ? US dkim_cur_sig->pubkey->granularity | |
485 | : dkim_exim_expand_defaults(what) | |
486 | : dkim_exim_expand_defaults(what); | |
487 | ||
488 | case DKIM_KEY_SRVTYPE: | |
489 | return dkim_cur_sig->pubkey | |
490 | ? dkim_cur_sig->pubkey->srvtype | |
491 | ? US dkim_cur_sig->pubkey->srvtype | |
492 | : dkim_exim_expand_defaults(what) | |
493 | : dkim_exim_expand_defaults(what); | |
494 | ||
495 | case DKIM_KEY_NOTES: | |
496 | return dkim_cur_sig->pubkey | |
497 | ? dkim_cur_sig->pubkey->notes | |
498 | ? US dkim_cur_sig->pubkey->notes | |
499 | : dkim_exim_expand_defaults(what) | |
500 | : dkim_exim_expand_defaults(what); | |
501 | ||
502 | case DKIM_KEY_TESTING: | |
503 | return dkim_cur_sig->pubkey | |
504 | ? dkim_cur_sig->pubkey->testing | |
505 | ? US"1" | |
506 | : dkim_exim_expand_defaults(what) | |
507 | : dkim_exim_expand_defaults(what); | |
508 | ||
509 | case DKIM_NOSUBDOMAINS: | |
510 | return dkim_cur_sig->pubkey | |
511 | ? dkim_cur_sig->pubkey->no_subdomaining | |
512 | ? US"1" | |
513 | : dkim_exim_expand_defaults(what) | |
514 | : dkim_exim_expand_defaults(what); | |
515 | ||
516 | case DKIM_VERIFY_STATUS: | |
517 | switch (dkim_cur_sig->verify_status) | |
518 | { | |
519 | case PDKIM_VERIFY_INVALID: return US"invalid"; | |
520 | case PDKIM_VERIFY_FAIL: return US"fail"; | |
521 | case PDKIM_VERIFY_PASS: return US"pass"; | |
522 | case PDKIM_VERIFY_NONE: | |
523 | default: return US"none"; | |
80a47a2c | 524 | } |
80a47a2c | 525 | |
1cfe5c1c JH |
526 | case DKIM_VERIFY_REASON: |
527 | switch (dkim_cur_sig->verify_ext_status) | |
528 | { | |
529 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
530 | return US"pubkey_unavailable"; | |
df3def24 JH |
531 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax"; |
532 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax"; | |
1cfe5c1c JH |
533 | case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch"; |
534 | case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect"; | |
535 | } | |
80a47a2c | 536 | |
1cfe5c1c JH |
537 | default: |
538 | return US""; | |
80a47a2c TK |
539 | } |
540 | } | |
541 | ||
542 | ||
0b8f4f1a | 543 | /* Generate signatures for the given file. |
42055a33 | 544 | If a prefix is given, prepend it to the file for the calculations. |
0b8f4f1a JH |
545 | |
546 | Return: | |
547 | NULL: error; error string written | |
548 | string: signature header(s), or a zero-length string (not an error) | |
42055a33 JH |
549 | */ |
550 | ||
acec9514 | 551 | gstring * |
42055a33 JH |
552 | dkim_exim_sign(int fd, off_t off, uschar * prefix, |
553 | struct ob_dkim * dkim, const uschar ** errstr) | |
55414b25 | 554 | { |
e983e85a | 555 | const uschar * dkim_domain; |
1cfe5c1c | 556 | int sep = 0; |
acec9514 | 557 | gstring * seen_doms = NULL; |
9e70917d JH |
558 | pdkim_ctx ctx; |
559 | pdkim_signature * sig; | |
acec9514 | 560 | gstring * sigbuf; |
1cfe5c1c JH |
561 | int pdkim_rc; |
562 | int sread; | |
ef698bf6 | 563 | uschar buf[4096]; |
1cfe5c1c JH |
564 | int save_errno = 0; |
565 | int old_pool = store_pool; | |
7c6ec81b | 566 | uschar * errwhen; |
1cfe5c1c JH |
567 | |
568 | store_pool = POOL_MAIN; | |
569 | ||
9e70917d JH |
570 | pdkim_init_context(&ctx, dkim->dot_stuffed, &dkim_exim_query_dns_txt); |
571 | ||
e983e85a | 572 | if (!(dkim_domain = expand_cstring(dkim->dkim_domain))) |
1cfe5c1c | 573 | /* expansion error, do not send message. */ |
7c6ec81b | 574 | { errwhen = US"dkim_domain"; goto expand_bad; } |
1cfe5c1c JH |
575 | |
576 | /* Set $dkim_domain expansion variable to each unique domain in list. */ | |
577 | ||
42055a33 | 578 | while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) |
1cfe5c1c | 579 | { |
9e70917d JH |
580 | const uschar * dkim_sel; |
581 | int sel_sep = 0; | |
582 | ||
42055a33 | 583 | if (dkim_signing_domain[0] == '\0') |
1cfe5c1c JH |
584 | continue; |
585 | ||
586 | /* Only sign once for each domain, no matter how often it | |
587 | appears in the expanded list. */ | |
588 | ||
9e70917d JH |
589 | if (match_isinlist(dkim_signing_domain, CUSS &seen_doms, |
590 | 0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK) | |
591 | continue; | |
1cfe5c1c | 592 | |
acec9514 | 593 | seen_doms = string_append_listele(seen_doms, ':', dkim_signing_domain); |
1cfe5c1c | 594 | |
9e70917d JH |
595 | /* Set $dkim_selector expansion variable to each selector in list, |
596 | for this domain. */ | |
1cfe5c1c | 597 | |
9e70917d | 598 | if (!(dkim_sel = expand_string(dkim->dkim_selector))) |
e983e85a | 599 | if (!(dkim_signing_selector = expand_string(dkim->dkim_selector))) |
7c6ec81b | 600 | { errwhen = US"dkim_selector"; goto expand_bad; } |
1cfe5c1c | 601 | |
9e70917d JH |
602 | while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep, |
603 | NULL, 0))) | |
1cfe5c1c | 604 | { |
9e70917d JH |
605 | uschar * dkim_canon_expanded; |
606 | int pdkim_canon; | |
607 | uschar * dkim_sign_headers_expanded = NULL; | |
608 | uschar * dkim_private_key_expanded; | |
609 | uschar * dkim_hash_expanded; | |
7c6ec81b | 610 | uschar * dkim_identity_expanded = NULL; |
80a47a2c | 611 | |
9e70917d | 612 | /* Get canonicalization to use */ |
1cfe5c1c | 613 | |
9e70917d JH |
614 | dkim_canon_expanded = dkim->dkim_canon |
615 | ? expand_string(dkim->dkim_canon) : US"relaxed"; | |
7c6ec81b JH |
616 | if (!dkim_canon_expanded) /* expansion error, do not send message. */ |
617 | { errwhen = US"dkim_canon"; goto expand_bad; } | |
1cfe5c1c | 618 | |
9e70917d JH |
619 | if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) |
620 | pdkim_canon = PDKIM_CANON_RELAXED; | |
621 | else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) | |
622 | pdkim_canon = PDKIM_CANON_SIMPLE; | |
623 | else | |
624 | { | |
625 | log_write(0, LOG_MAIN, | |
626 | "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", | |
627 | dkim_canon_expanded); | |
628 | pdkim_canon = PDKIM_CANON_RELAXED; | |
629 | } | |
1cfe5c1c | 630 | |
7c6ec81b JH |
631 | if ( dkim->dkim_sign_headers |
632 | && !(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) | |
633 | { errwhen = US"dkim_sign_header"; goto expand_bad; } | |
634 | /* else pass NULL, which means default header list */ | |
1cfe5c1c | 635 | |
9e70917d | 636 | /* Get private key to use. */ |
e983e85a | 637 | |
9e70917d | 638 | if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) |
7c6ec81b | 639 | { errwhen = US"dkim_private_key"; goto expand_bad; } |
80a47a2c | 640 | |
9e70917d JH |
641 | if ( Ustrlen(dkim_private_key_expanded) == 0 |
642 | || Ustrcmp(dkim_private_key_expanded, "0") == 0 | |
643 | || Ustrcmp(dkim_private_key_expanded, "false") == 0 | |
644 | ) | |
645 | continue; /* don't sign, but no error */ | |
646 | ||
647 | if (dkim_private_key_expanded[0] == '/') | |
1cfe5c1c | 648 | { |
9e70917d JH |
649 | int privkey_fd, off = 0, len; |
650 | ||
651 | /* Looks like a filename, load the private key. */ | |
652 | ||
653 | memset(big_buffer, 0, big_buffer_size); | |
654 | ||
655 | if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0) | |
59d98039 | 656 | { |
9e70917d JH |
657 | log_write(0, LOG_MAIN | LOG_PANIC, "unable to open " |
658 | "private key file for reading: %s", | |
59d98039 JH |
659 | dkim_private_key_expanded); |
660 | goto bad; | |
661 | } | |
9e70917d JH |
662 | |
663 | do | |
664 | { | |
665 | if ((len = read(privkey_fd, big_buffer + off, big_buffer_size - 2 - off)) < 0) | |
666 | { | |
667 | (void) close(privkey_fd); | |
668 | log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s", | |
669 | dkim_private_key_expanded); | |
670 | goto bad; | |
671 | } | |
672 | off += len; | |
673 | } | |
674 | while (len > 0); | |
675 | ||
676 | (void) close(privkey_fd); | |
677 | big_buffer[off] = '\0'; | |
678 | dkim_private_key_expanded = big_buffer; | |
1ac6b2e7 | 679 | } |
80a47a2c | 680 | |
9e70917d | 681 | if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash))) |
7c6ec81b JH |
682 | { errwhen = US"dkim_hash"; goto expand_bad; } |
683 | ||
684 | if (dkim->dkim_identity) | |
685 | if (!(dkim_identity_expanded = expand_string(dkim->dkim_identity))) | |
686 | { errwhen = US"dkim_identity"; goto expand_bad; } | |
687 | else if (!*dkim_identity_expanded) | |
688 | dkim_identity_expanded = NULL; | |
1cfe5c1c | 689 | |
9e70917d JH |
690 | /*XXX so we currently nail signing to RSA + this hash. |
691 | Need to extract algo from privkey and check for disallowed combos. */ | |
d73e45df | 692 | |
9e70917d JH |
693 | if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain, |
694 | dkim_signing_selector, | |
695 | dkim_private_key_expanded, | |
696 | dkim_hash_expanded, | |
697 | errstr | |
698 | ))) | |
699 | goto bad; | |
700 | dkim_private_key_expanded[0] = '\0'; | |
701 | ||
702 | pdkim_set_optional(sig, | |
703 | CS dkim_sign_headers_expanded, | |
27fd1318 | 704 | CS dkim_identity_expanded, |
9e70917d JH |
705 | pdkim_canon, |
706 | pdkim_canon, -1, 0, 0); | |
707 | ||
708 | if (!ctx.sig) /* link sig to context chain */ | |
709 | ctx.sig = sig; | |
710 | else | |
711 | { | |
712 | pdkim_signature * n = ctx.sig; | |
713 | while (n->next) n = n->next; | |
714 | n->next = sig; | |
715 | } | |
80a47a2c | 716 | } |
9e70917d | 717 | } |
0b8f4f1a JH |
718 | if (!ctx.sig) |
719 | { | |
720 | DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n"); | |
721 | sigbuf = string_get(1); /* return a zero-len string */ | |
722 | goto CLEANUP; | |
723 | } | |
80a47a2c | 724 | |
0b8f4f1a JH |
725 | if (prefix && (pdkim_feed(&ctx, prefix, Ustrlen(prefix))) != PDKIM_OK) |
726 | goto pk_bad; | |
80a47a2c | 727 | |
9e70917d JH |
728 | if (lseek(fd, off, SEEK_SET) < 0) |
729 | sread = -1; | |
730 | else | |
731 | while ((sread = read(fd, &buf, sizeof(buf))) > 0) | |
732 | if ((pdkim_rc = pdkim_feed(&ctx, buf, sread)) != PDKIM_OK) | |
733 | goto pk_bad; | |
80a47a2c | 734 | |
9e70917d JH |
735 | /* Handle failed read above. */ |
736 | if (sread == -1) | |
737 | { | |
738 | debug_printf("DKIM: Error reading -K file.\n"); | |
739 | save_errno = errno; | |
740 | goto bad; | |
80a47a2c | 741 | } |
a8e1eeba | 742 | |
9e70917d JH |
743 | /* Build string of headers, one per signature */ |
744 | ||
745 | if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK) | |
746 | goto pk_bad; | |
747 | ||
acec9514 JH |
748 | for (sigbuf = NULL; sig; sig = sig->next) |
749 | sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n"); | |
9e70917d | 750 | |
1cfe5c1c | 751 | CLEANUP: |
0b8f4f1a | 752 | (void) string_from_gstring(sigbuf); |
f7302073 JH |
753 | store_pool = old_pool; |
754 | errno = save_errno; | |
9e70917d | 755 | return sigbuf; |
f7302073 JH |
756 | |
757 | pk_bad: | |
758 | log_write(0, LOG_MAIN|LOG_PANIC, | |
759 | "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc)); | |
760 | bad: | |
9e70917d | 761 | sigbuf = NULL; |
f7302073 | 762 | goto CLEANUP; |
7c6ec81b JH |
763 | |
764 | expand_bad: | |
765 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand %s: %s", | |
766 | errwhen, expand_string_message); | |
767 | goto bad; | |
93f2d376 | 768 | } |
80a47a2c | 769 | |
970424a5 JH |
770 | # endif /*!MACRO_PREDEF*/ |
771 | #endif /*!DISABLE_DKIM*/ |