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80a47a2c TK |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
f9ba5e22 | 5 | /* Copyright (c) University of Cambridge, 1995 - 2018 */ |
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. | |
d73e45df JH |
39 | */ |
40 | ||
1eedc10f JH |
41 | static uschar * |
42 | dkim_exim_query_dns_txt(char * name) | |
1cfe5c1c JH |
43 | { |
44 | dns_answer dnsa; | |
45 | dns_scan dnss; | |
46 | dns_record *rr; | |
1eedc10f | 47 | gstring * g = NULL; |
80a47a2c | 48 | |
1cfe5c1c JH |
49 | lookup_dnssec_authenticated = NULL; |
50 | if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED) | |
1eedc10f | 51 | return NULL; /*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 | 60 | int rr_offset = 0; |
1cfe5c1c JH |
61 | |
62 | /* Copy record content to the answer buffer */ | |
63 | ||
64 | while (rr_offset < rr->size) | |
65 | { | |
66 | uschar len = rr->data[rr_offset++]; | |
1eedc10f JH |
67 | |
68 | g = string_catn(g, US(rr->data + rr_offset), len); | |
69 | if (g->ptr >= PDKIM_DNS_TXT_MAX_RECLEN) | |
70 | goto bad; | |
71 | ||
1cfe5c1c | 72 | rr_offset += len; |
4263f395 | 73 | } |
dd33c4e6 HSHR |
74 | |
75 | /* check if this looks like a DKIM record */ | |
d011368a | 76 | if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0) |
1eedc10f JH |
77 | { |
78 | store_reset(g->s + g->ptr + 1); | |
79 | return string_from_gstring(g); | |
80 | } | |
81 | ||
82 | if (g) g->ptr = 0; /* overwrite previous record */ | |
80a47a2c | 83 | } |
80a47a2c | 84 | |
1eedc10f JH |
85 | bad: |
86 | if (g) store_reset(g); | |
87 | return NULL; /*XXX better error detail? logging? */ | |
80a47a2c TK |
88 | } |
89 | ||
90 | ||
2592e6c0 JH |
91 | void |
92 | dkim_exim_init(void) | |
93 | { | |
94 | pdkim_init(); | |
95 | } | |
96 | ||
97 | ||
ca9cb170 | 98 | |
1cfe5c1c | 99 | void |
e983e85a | 100 | dkim_exim_verify_init(BOOL dot_stuffing) |
1cfe5c1c | 101 | { |
ca9cb170 JH |
102 | /* There is a store-reset between header & body reception |
103 | so cannot use the main pool. Any allocs done by Exim | |
104 | memory-handling must use the perm pool. */ | |
105 | ||
106 | dkim_verify_oldpool = store_pool; | |
107 | store_pool = POOL_PERM; | |
108 | ||
1cfe5c1c | 109 | /* Free previous context if there is one */ |
80a47a2c | 110 | |
1cfe5c1c JH |
111 | if (dkim_verify_ctx) |
112 | pdkim_free_ctx(dkim_verify_ctx); | |
80a47a2c | 113 | |
1cfe5c1c | 114 | /* Create new context */ |
80a47a2c | 115 | |
e983e85a | 116 | dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing); |
3b957582 | 117 | dkim_collect_input = !!dkim_verify_ctx; |
b9df1829 | 118 | dkim_collect_error = NULL; |
ca9cb170 | 119 | |
584e96c6 JH |
120 | /* Start feed up with any cached data */ |
121 | receive_get_cache(); | |
122 | ||
ca9cb170 | 123 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
124 | } |
125 | ||
126 | ||
1cfe5c1c JH |
127 | void |
128 | dkim_exim_verify_feed(uschar * data, int len) | |
129 | { | |
f7302073 JH |
130 | int rc; |
131 | ||
ca9cb170 | 132 | store_pool = POOL_PERM; |
1cfe5c1c | 133 | if ( dkim_collect_input |
ef698bf6 | 134 | && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK) |
f7302073 | 135 | { |
b9df1829 | 136 | dkim_collect_error = pdkim_errstr(rc); |
f7302073 | 137 | log_write(0, LOG_MAIN, |
b9df1829 | 138 | "DKIM: validation error: %.100s", dkim_collect_error); |
1cfe5c1c | 139 | dkim_collect_input = FALSE; |
f7302073 | 140 | } |
ca9cb170 | 141 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
142 | } |
143 | ||
144 | ||
a79d8834 JH |
145 | /* Log the result for the given signature */ |
146 | static void | |
147 | dkim_exim_verify_log_sig(pdkim_signature * sig) | |
1cfe5c1c | 148 | { |
cc55f420 | 149 | gstring * logmsg; |
a79d8834 JH |
150 | uschar * s; |
151 | ||
cc55f420 JH |
152 | if (!sig) return; |
153 | ||
dfbcb5ac JH |
154 | if ( dkim_verify_status |
155 | && ( dkim_verify_status != dkim_exim_expand_query(DKIM_VERIFY_STATUS) | |
156 | || dkim_verify_reason != dkim_exim_expand_query(DKIM_VERIFY_REASON) | |
157 | ) ) | |
158 | sig->verify_status |= PDKIM_VERIFY_POLICY; | |
159 | ||
2c47372f JH |
160 | if ( !dkim_verify_overall |
161 | && dkim_verify_status | |
162 | ? Ustrcmp(dkim_verify_status, US"pass") == 0 | |
163 | : sig->verify_status == PDKIM_VERIFY_PASS | |
164 | ) | |
165 | dkim_verify_overall = string_copy(sig->domain); | |
166 | ||
167 | if (!LOGGING(dkim_verbose)) return; | |
168 | ||
aaaa94ea | 169 | logmsg = string_catn(NULL, US"DKIM: ", 6); |
a79d8834 JH |
170 | if (!(s = sig->domain)) s = US"<UNSET>"; |
171 | logmsg = string_append(logmsg, 2, "d=", s); | |
172 | if (!(s = sig->selector)) s = US"<UNSET>"; | |
173 | logmsg = string_append(logmsg, 2, " s=", s); | |
dd33c4e6 | 174 | logmsg = string_append(logmsg, 7, |
dfbcb5ac JH |
175 | " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", |
176 | "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", | |
177 | " a=", dkim_sig_to_a_tag(sig), | |
a79d8834 JH |
178 | string_sprintf(" b=" SIZE_T_FMT, |
179 | (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0)); | |
180 | if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s); | |
181 | if (sig->created > 0) logmsg = string_cat(logmsg, | |
182 | string_sprintf(" t=%lu", sig->created)); | |
183 | if (sig->expires > 0) logmsg = string_cat(logmsg, | |
184 | string_sprintf(" x=%lu", sig->expires)); | |
185 | if (sig->bodylength > -1) logmsg = string_cat(logmsg, | |
186 | string_sprintf(" l=%lu", sig->bodylength)); | |
187 | ||
dfbcb5ac JH |
188 | if (sig->verify_status & PDKIM_VERIFY_POLICY) |
189 | logmsg = string_append(logmsg, 5, | |
190 | US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]"); | |
191 | else | |
1cfe5c1c JH |
192 | switch (sig->verify_status) |
193 | { | |
194 | case PDKIM_VERIFY_NONE: | |
aaaa94ea | 195 | logmsg = string_cat(logmsg, US" [not verified]"); |
80a47a2c | 196 | break; |
1cfe5c1c JH |
197 | |
198 | case PDKIM_VERIFY_INVALID: | |
aaaa94ea | 199 | logmsg = string_cat(logmsg, US" [invalid - "); |
1cfe5c1c JH |
200 | switch (sig->verify_ext_status) |
201 | { | |
202 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
acec9514 | 203 | logmsg = string_cat(logmsg, |
aaaa94ea | 204 | US"public key record (currently?) unavailable]"); |
1cfe5c1c JH |
205 | break; |
206 | ||
207 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: | |
aaaa94ea | 208 | logmsg = string_cat(logmsg, US"overlong public key record]"); |
1cfe5c1c JH |
209 | break; |
210 | ||
df3def24 JH |
211 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: |
212 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: | |
aaaa94ea | 213 | logmsg = string_cat(logmsg, US"syntax error in public key record]"); |
1cfe5c1c | 214 | break; |
07eeb4df | 215 | |
a79d8834 | 216 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: |
aaaa94ea | 217 | logmsg = string_cat(logmsg, US"signature tag missing or invalid]"); |
a79d8834 | 218 | break; |
07eeb4df | 219 | |
a79d8834 | 220 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: |
aaaa94ea | 221 | logmsg = string_cat(logmsg, US"unsupported DKIM version]"); |
a79d8834 | 222 | break; |
1cfe5c1c JH |
223 | |
224 | default: | |
aaaa94ea | 225 | logmsg = string_cat(logmsg, US"unspecified problem]"); |
1cfe5c1c | 226 | } |
80a47a2c | 227 | break; |
1cfe5c1c JH |
228 | |
229 | case PDKIM_VERIFY_FAIL: | |
aaaa94ea | 230 | logmsg = string_cat(logmsg, US" [verification failed - "); |
1cfe5c1c JH |
231 | switch (sig->verify_ext_status) |
232 | { | |
233 | case PDKIM_VERIFY_FAIL_BODY: | |
acec9514 | 234 | logmsg = string_cat(logmsg, |
aaaa94ea | 235 | US"body hash mismatch (body probably modified in transit)]"); |
1cfe5c1c JH |
236 | break; |
237 | ||
238 | case PDKIM_VERIFY_FAIL_MESSAGE: | |
acec9514 | 239 | logmsg = string_cat(logmsg, |
aaaa94ea JH |
240 | US"signature did not verify " |
241 | "(headers probably modified in transit)]"); | |
dfbcb5ac | 242 | break; |
1cfe5c1c JH |
243 | |
244 | default: | |
aaaa94ea | 245 | logmsg = string_cat(logmsg, US"unspecified reason]"); |
1cfe5c1c | 246 | } |
80a47a2c | 247 | break; |
1cfe5c1c JH |
248 | |
249 | case PDKIM_VERIFY_PASS: | |
aaaa94ea | 250 | logmsg = string_cat(logmsg, US" [verification succeeded]"); |
80a47a2c TK |
251 | break; |
252 | } | |
a79d8834 | 253 | |
aaaa94ea | 254 | log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg)); |
a79d8834 JH |
255 | return; |
256 | } | |
257 | ||
80a47a2c | 258 | |
a79d8834 JH |
259 | /* Log a line for each signature */ |
260 | void | |
261 | dkim_exim_verify_log_all(void) | |
262 | { | |
263 | pdkim_signature * sig; | |
264 | for (sig = dkim_signatures; sig; sig = sig->next) dkim_exim_verify_log_sig(sig); | |
265 | } | |
1cfe5c1c | 266 | |
80a47a2c | 267 | |
a79d8834 JH |
268 | void |
269 | dkim_exim_verify_finish(void) | |
270 | { | |
271 | pdkim_signature * sig; | |
272 | int rc; | |
273 | gstring * g = NULL; | |
286b9d5f | 274 | const uschar * errstr = NULL; |
a79d8834 JH |
275 | |
276 | store_pool = POOL_PERM; | |
277 | ||
278 | /* Delete eventual previous signature chain */ | |
279 | ||
280 | dkim_signers = NULL; | |
281 | dkim_signatures = NULL; | |
282 | ||
283 | if (dkim_collect_error) | |
284 | { | |
285 | log_write(0, LOG_MAIN, | |
286 | "DKIM: Error during validation, disabling signature verification: %.100s", | |
287 | dkim_collect_error); | |
288 | dkim_disable_verify = TRUE; | |
289 | goto out; | |
290 | } | |
291 | ||
292 | dkim_collect_input = FALSE; | |
293 | ||
294 | /* Finish DKIM operation and fetch link to signatures chain */ | |
295 | ||
296 | rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr); | |
286b9d5f JH |
297 | if (rc != PDKIM_OK && errstr) |
298 | log_write(0, LOG_MAIN, "DKIM: validation error: %s", errstr); | |
a79d8834 JH |
299 | |
300 | /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ | |
301 | ||
302 | for (sig = dkim_signatures; sig; sig = sig->next) | |
303 | { | |
304 | if (sig->domain) g = string_append_listele(g, ':', sig->domain); | |
305 | if (sig->identity) g = string_append_listele(g, ':', sig->identity); | |
80a47a2c TK |
306 | } |
307 | ||
acec9514 JH |
308 | if (g) dkim_signers = g->s; |
309 | ||
ca9cb170 JH |
310 | out: |
311 | store_pool = dkim_verify_oldpool; | |
80a47a2c TK |
312 | } |
313 | ||
314 | ||
18067c75 JH |
315 | |
316 | /* Args as per dkim_exim_acl_run() below */ | |
317 | static int | |
318 | dkim_acl_call(uschar * id, gstring ** res_ptr, | |
319 | uschar ** user_msgptr, uschar ** log_msgptr) | |
320 | { | |
321 | int rc; | |
322 | DEBUG(D_receive) | |
323 | debug_printf("calling acl_smtp_dkim for dkim_cur_signer='%s'\n", id); | |
324 | ||
325 | rc = acl_check(ACL_WHERE_DKIM, NULL, acl_smtp_dkim, user_msgptr, log_msgptr); | |
326 | dkim_exim_verify_log_sig(dkim_cur_sig); | |
327 | *res_ptr = string_append_listele(*res_ptr, ':', dkim_verify_status); | |
328 | return rc; | |
329 | } | |
330 | ||
331 | ||
332 | ||
333 | /* For the given identity, run the DKIM ACL once for each matching signature. | |
334 | ||
335 | Arguments | |
336 | id Identity to look for in dkim signatures | |
337 | res_ptr ptr to growable string-list of status results, | |
338 | appended to per ACL run | |
339 | user_msgptr where to put a user error (for SMTP response) | |
340 | log_msgptr where to put a logging message (not for SMTP response) | |
341 | ||
342 | Returns: OK access is granted by an ACCEPT verb | |
343 | DISCARD access is granted by a DISCARD verb | |
344 | FAIL access is denied | |
345 | FAIL_DROP access is denied; drop the connection | |
346 | DEFER can't tell at the moment | |
347 | ERROR disaster | |
348 | */ | |
349 | ||
350 | int | |
351 | dkim_exim_acl_run(uschar * id, gstring ** res_ptr, | |
352 | uschar ** user_msgptr, uschar ** log_msgptr) | |
1cfe5c1c JH |
353 | { |
354 | pdkim_signature * sig; | |
355 | uschar * cmp_val; | |
18067c75 | 356 | int rc = -1; |
1cfe5c1c | 357 | |
cc55f420 JH |
358 | dkim_verify_status = US"none"; |
359 | dkim_verify_reason = US""; | |
1cfe5c1c JH |
360 | dkim_cur_signer = id; |
361 | ||
362 | if (dkim_disable_verify || !id || !dkim_verify_ctx) | |
18067c75 | 363 | return OK; |
1cfe5c1c | 364 | |
18067c75 | 365 | /* Find signatures to run ACL on */ |
1cfe5c1c JH |
366 | |
367 | for (sig = dkim_signatures; sig; sig = sig->next) | |
368 | if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain) | |
369 | && strcmpic(cmp_val, id) == 0 | |
370 | ) | |
371 | { | |
1cfe5c1c | 372 | /* The "dkim_domain" and "dkim_selector" expansion variables have |
18067c75 JH |
373 | related globals, since they are used in the signing code too. |
374 | Instead of inventing separate names for verification, we set | |
375 | them here. This is easy since a domain and selector is guaranteed | |
376 | to be in a signature. The other dkim_* expansion items are | |
377 | dynamically fetched from dkim_cur_sig at expansion time (see | |
378 | function below). */ | |
1cfe5c1c | 379 | |
18067c75 | 380 | dkim_cur_sig = sig; |
1cfe5c1c JH |
381 | dkim_signing_domain = US sig->domain; |
382 | dkim_signing_selector = US sig->selector; | |
dcd03763 | 383 | dkim_key_length = sig->sighash.len * 8; |
a79d8834 JH |
384 | |
385 | /* These two return static strings, so we can compare the addr | |
386 | later to see if the ACL overwrote them. Check that when logging */ | |
387 | ||
388 | dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS); | |
389 | dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON); | |
dd33c4e6 | 390 | |
18067c75 JH |
391 | if ((rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK) |
392 | return rc; | |
80a47a2c | 393 | } |
18067c75 JH |
394 | |
395 | if (rc != -1) | |
396 | return rc; | |
397 | ||
398 | /* No matching sig found. Call ACL once anyway. */ | |
399 | ||
400 | dkim_cur_sig = NULL; | |
401 | return dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr); | |
80a47a2c TK |
402 | } |
403 | ||
404 | ||
1cfe5c1c JH |
405 | static uschar * |
406 | dkim_exim_expand_defaults(int what) | |
407 | { | |
408 | switch (what) | |
409 | { | |
410 | case DKIM_ALGO: return US""; | |
411 | case DKIM_BODYLENGTH: return US"9999999999999"; | |
412 | case DKIM_CANON_BODY: return US""; | |
413 | case DKIM_CANON_HEADERS: return US""; | |
414 | case DKIM_COPIEDHEADERS: return US""; | |
415 | case DKIM_CREATED: return US"0"; | |
416 | case DKIM_EXPIRES: return US"9999999999999"; | |
417 | case DKIM_HEADERNAMES: return US""; | |
418 | case DKIM_IDENTITY: return US""; | |
419 | case DKIM_KEY_GRANULARITY: return US"*"; | |
420 | case DKIM_KEY_SRVTYPE: return US"*"; | |
421 | case DKIM_KEY_NOTES: return US""; | |
422 | case DKIM_KEY_TESTING: return US"0"; | |
423 | case DKIM_NOSUBDOMAINS: return US"0"; | |
424 | case DKIM_VERIFY_STATUS: return US"none"; | |
425 | case DKIM_VERIFY_REASON: return US""; | |
426 | default: return US""; | |
427 | } | |
428 | } | |
80a47a2c | 429 | |
80a47a2c | 430 | |
1cfe5c1c JH |
431 | uschar * |
432 | dkim_exim_expand_query(int what) | |
433 | { | |
434 | if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig) | |
435 | return dkim_exim_expand_defaults(what); | |
436 | ||
437 | switch (what) | |
438 | { | |
439 | case DKIM_ALGO: | |
d73e45df | 440 | return dkim_sig_to_a_tag(dkim_cur_sig); |
1cfe5c1c JH |
441 | |
442 | case DKIM_BODYLENGTH: | |
443 | return dkim_cur_sig->bodylength >= 0 | |
bb07bcd3 | 444 | ? string_sprintf("%ld", dkim_cur_sig->bodylength) |
1cfe5c1c JH |
445 | : dkim_exim_expand_defaults(what); |
446 | ||
447 | case DKIM_CANON_BODY: | |
448 | switch (dkim_cur_sig->canon_body) | |
449 | { | |
450 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
451 | case PDKIM_CANON_SIMPLE: | |
452 | default: return US"simple"; | |
80a47a2c | 453 | } |
1cfe5c1c JH |
454 | |
455 | case DKIM_CANON_HEADERS: | |
a79d8834 JH |
456 | switch (dkim_cur_sig->canon_headers) |
457 | { | |
458 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
459 | case PDKIM_CANON_SIMPLE: | |
460 | default: return US"simple"; | |
461 | } | |
1cfe5c1c JH |
462 | |
463 | case DKIM_COPIEDHEADERS: | |
464 | return dkim_cur_sig->copiedheaders | |
465 | ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what); | |
466 | ||
467 | case DKIM_CREATED: | |
468 | return dkim_cur_sig->created > 0 | |
bb07bcd3 | 469 | ? string_sprintf("%lu", dkim_cur_sig->created) |
1cfe5c1c JH |
470 | : dkim_exim_expand_defaults(what); |
471 | ||
472 | case DKIM_EXPIRES: | |
473 | return dkim_cur_sig->expires > 0 | |
bb07bcd3 | 474 | ? string_sprintf("%lu", dkim_cur_sig->expires) |
1cfe5c1c JH |
475 | : dkim_exim_expand_defaults(what); |
476 | ||
477 | case DKIM_HEADERNAMES: | |
478 | return dkim_cur_sig->headernames | |
2592e6c0 | 479 | ? dkim_cur_sig->headernames : dkim_exim_expand_defaults(what); |
1cfe5c1c JH |
480 | |
481 | case DKIM_IDENTITY: | |
482 | return dkim_cur_sig->identity | |
483 | ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what); | |
484 | ||
485 | case DKIM_KEY_GRANULARITY: | |
486 | return dkim_cur_sig->pubkey | |
487 | ? dkim_cur_sig->pubkey->granularity | |
488 | ? US dkim_cur_sig->pubkey->granularity | |
489 | : dkim_exim_expand_defaults(what) | |
490 | : dkim_exim_expand_defaults(what); | |
491 | ||
492 | case DKIM_KEY_SRVTYPE: | |
493 | return dkim_cur_sig->pubkey | |
494 | ? dkim_cur_sig->pubkey->srvtype | |
495 | ? US dkim_cur_sig->pubkey->srvtype | |
496 | : dkim_exim_expand_defaults(what) | |
497 | : dkim_exim_expand_defaults(what); | |
498 | ||
499 | case DKIM_KEY_NOTES: | |
500 | return dkim_cur_sig->pubkey | |
501 | ? dkim_cur_sig->pubkey->notes | |
502 | ? US dkim_cur_sig->pubkey->notes | |
503 | : dkim_exim_expand_defaults(what) | |
504 | : dkim_exim_expand_defaults(what); | |
505 | ||
506 | case DKIM_KEY_TESTING: | |
507 | return dkim_cur_sig->pubkey | |
508 | ? dkim_cur_sig->pubkey->testing | |
509 | ? US"1" | |
510 | : dkim_exim_expand_defaults(what) | |
511 | : dkim_exim_expand_defaults(what); | |
512 | ||
513 | case DKIM_NOSUBDOMAINS: | |
514 | return dkim_cur_sig->pubkey | |
515 | ? dkim_cur_sig->pubkey->no_subdomaining | |
516 | ? US"1" | |
517 | : dkim_exim_expand_defaults(what) | |
518 | : dkim_exim_expand_defaults(what); | |
519 | ||
520 | case DKIM_VERIFY_STATUS: | |
521 | switch (dkim_cur_sig->verify_status) | |
522 | { | |
523 | case PDKIM_VERIFY_INVALID: return US"invalid"; | |
524 | case PDKIM_VERIFY_FAIL: return US"fail"; | |
525 | case PDKIM_VERIFY_PASS: return US"pass"; | |
526 | case PDKIM_VERIFY_NONE: | |
527 | default: return US"none"; | |
80a47a2c | 528 | } |
80a47a2c | 529 | |
1cfe5c1c JH |
530 | case DKIM_VERIFY_REASON: |
531 | switch (dkim_cur_sig->verify_ext_status) | |
532 | { | |
533 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
534 | return US"pubkey_unavailable"; | |
df3def24 JH |
535 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax"; |
536 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax"; | |
1cfe5c1c JH |
537 | case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch"; |
538 | case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect"; | |
539 | } | |
80a47a2c | 540 | |
1cfe5c1c JH |
541 | default: |
542 | return US""; | |
80a47a2c TK |
543 | } |
544 | } | |
545 | ||
546 | ||
0b8f4f1a | 547 | /* Generate signatures for the given file. |
42055a33 | 548 | If a prefix is given, prepend it to the file for the calculations. |
0b8f4f1a JH |
549 | |
550 | Return: | |
551 | NULL: error; error string written | |
552 | string: signature header(s), or a zero-length string (not an error) | |
42055a33 JH |
553 | */ |
554 | ||
acec9514 | 555 | gstring * |
42055a33 JH |
556 | dkim_exim_sign(int fd, off_t off, uschar * prefix, |
557 | struct ob_dkim * dkim, const uschar ** errstr) | |
55414b25 | 558 | { |
e983e85a | 559 | const uschar * dkim_domain; |
1cfe5c1c | 560 | int sep = 0; |
acec9514 | 561 | gstring * seen_doms = NULL; |
9e70917d JH |
562 | pdkim_ctx ctx; |
563 | pdkim_signature * sig; | |
acec9514 | 564 | gstring * sigbuf; |
1cfe5c1c JH |
565 | int pdkim_rc; |
566 | int sread; | |
ef698bf6 | 567 | uschar buf[4096]; |
1cfe5c1c JH |
568 | int save_errno = 0; |
569 | int old_pool = store_pool; | |
7c6ec81b | 570 | uschar * errwhen; |
1cfe5c1c JH |
571 | |
572 | store_pool = POOL_MAIN; | |
573 | ||
9e70917d JH |
574 | pdkim_init_context(&ctx, dkim->dot_stuffed, &dkim_exim_query_dns_txt); |
575 | ||
e983e85a | 576 | if (!(dkim_domain = expand_cstring(dkim->dkim_domain))) |
1cfe5c1c | 577 | /* expansion error, do not send message. */ |
7c6ec81b | 578 | { errwhen = US"dkim_domain"; goto expand_bad; } |
1cfe5c1c JH |
579 | |
580 | /* Set $dkim_domain expansion variable to each unique domain in list. */ | |
581 | ||
42055a33 | 582 | while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) |
1cfe5c1c | 583 | { |
9e70917d JH |
584 | const uschar * dkim_sel; |
585 | int sel_sep = 0; | |
586 | ||
42055a33 | 587 | if (dkim_signing_domain[0] == '\0') |
1cfe5c1c JH |
588 | continue; |
589 | ||
590 | /* Only sign once for each domain, no matter how often it | |
591 | appears in the expanded list. */ | |
592 | ||
9e70917d JH |
593 | if (match_isinlist(dkim_signing_domain, CUSS &seen_doms, |
594 | 0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK) | |
595 | continue; | |
1cfe5c1c | 596 | |
acec9514 | 597 | seen_doms = string_append_listele(seen_doms, ':', dkim_signing_domain); |
1cfe5c1c | 598 | |
9e70917d JH |
599 | /* Set $dkim_selector expansion variable to each selector in list, |
600 | for this domain. */ | |
1cfe5c1c | 601 | |
9e70917d | 602 | if (!(dkim_sel = expand_string(dkim->dkim_selector))) |
e983e85a | 603 | if (!(dkim_signing_selector = expand_string(dkim->dkim_selector))) |
7c6ec81b | 604 | { errwhen = US"dkim_selector"; goto expand_bad; } |
1cfe5c1c | 605 | |
9e70917d JH |
606 | while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep, |
607 | NULL, 0))) | |
1cfe5c1c | 608 | { |
9e70917d JH |
609 | uschar * dkim_canon_expanded; |
610 | int pdkim_canon; | |
611 | uschar * dkim_sign_headers_expanded = NULL; | |
612 | uschar * dkim_private_key_expanded; | |
613 | uschar * dkim_hash_expanded; | |
7c6ec81b | 614 | uschar * dkim_identity_expanded = NULL; |
80a47a2c | 615 | |
9e70917d | 616 | /* Get canonicalization to use */ |
1cfe5c1c | 617 | |
9e70917d JH |
618 | dkim_canon_expanded = dkim->dkim_canon |
619 | ? expand_string(dkim->dkim_canon) : US"relaxed"; | |
7c6ec81b JH |
620 | if (!dkim_canon_expanded) /* expansion error, do not send message. */ |
621 | { errwhen = US"dkim_canon"; goto expand_bad; } | |
1cfe5c1c | 622 | |
9e70917d JH |
623 | if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) |
624 | pdkim_canon = PDKIM_CANON_RELAXED; | |
625 | else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) | |
626 | pdkim_canon = PDKIM_CANON_SIMPLE; | |
627 | else | |
628 | { | |
629 | log_write(0, LOG_MAIN, | |
630 | "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", | |
631 | dkim_canon_expanded); | |
632 | pdkim_canon = PDKIM_CANON_RELAXED; | |
633 | } | |
1cfe5c1c | 634 | |
7c6ec81b JH |
635 | if ( dkim->dkim_sign_headers |
636 | && !(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) | |
637 | { errwhen = US"dkim_sign_header"; goto expand_bad; } | |
638 | /* else pass NULL, which means default header list */ | |
1cfe5c1c | 639 | |
9e70917d | 640 | /* Get private key to use. */ |
e983e85a | 641 | |
9e70917d | 642 | if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) |
7c6ec81b | 643 | { errwhen = US"dkim_private_key"; goto expand_bad; } |
80a47a2c | 644 | |
9e70917d JH |
645 | if ( Ustrlen(dkim_private_key_expanded) == 0 |
646 | || Ustrcmp(dkim_private_key_expanded, "0") == 0 | |
647 | || Ustrcmp(dkim_private_key_expanded, "false") == 0 | |
648 | ) | |
649 | continue; /* don't sign, but no error */ | |
650 | ||
651 | if (dkim_private_key_expanded[0] == '/') | |
1cfe5c1c | 652 | { |
9e70917d JH |
653 | int privkey_fd, off = 0, len; |
654 | ||
655 | /* Looks like a filename, load the private key. */ | |
656 | ||
657 | memset(big_buffer, 0, big_buffer_size); | |
658 | ||
659 | if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0) | |
59d98039 | 660 | { |
9e70917d JH |
661 | log_write(0, LOG_MAIN | LOG_PANIC, "unable to open " |
662 | "private key file for reading: %s", | |
59d98039 JH |
663 | dkim_private_key_expanded); |
664 | goto bad; | |
665 | } | |
9e70917d JH |
666 | |
667 | do | |
668 | { | |
669 | if ((len = read(privkey_fd, big_buffer + off, big_buffer_size - 2 - off)) < 0) | |
670 | { | |
671 | (void) close(privkey_fd); | |
672 | log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s", | |
673 | dkim_private_key_expanded); | |
674 | goto bad; | |
675 | } | |
676 | off += len; | |
677 | } | |
678 | while (len > 0); | |
679 | ||
680 | (void) close(privkey_fd); | |
681 | big_buffer[off] = '\0'; | |
682 | dkim_private_key_expanded = big_buffer; | |
1ac6b2e7 | 683 | } |
80a47a2c | 684 | |
9e70917d | 685 | if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash))) |
7c6ec81b JH |
686 | { errwhen = US"dkim_hash"; goto expand_bad; } |
687 | ||
688 | if (dkim->dkim_identity) | |
689 | if (!(dkim_identity_expanded = expand_string(dkim->dkim_identity))) | |
690 | { errwhen = US"dkim_identity"; goto expand_bad; } | |
691 | else if (!*dkim_identity_expanded) | |
692 | dkim_identity_expanded = NULL; | |
1cfe5c1c | 693 | |
9e70917d JH |
694 | /*XXX so we currently nail signing to RSA + this hash. |
695 | Need to extract algo from privkey and check for disallowed combos. */ | |
d73e45df | 696 | |
9e70917d JH |
697 | if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain, |
698 | dkim_signing_selector, | |
699 | dkim_private_key_expanded, | |
700 | dkim_hash_expanded, | |
701 | errstr | |
702 | ))) | |
703 | goto bad; | |
704 | dkim_private_key_expanded[0] = '\0'; | |
705 | ||
706 | pdkim_set_optional(sig, | |
707 | CS dkim_sign_headers_expanded, | |
27fd1318 | 708 | CS dkim_identity_expanded, |
9e70917d JH |
709 | pdkim_canon, |
710 | pdkim_canon, -1, 0, 0); | |
711 | ||
cf1cce5e JH |
712 | if (!pdkim_set_bodyhash(&ctx, sig)) |
713 | goto bad; | |
714 | ||
9e70917d JH |
715 | if (!ctx.sig) /* link sig to context chain */ |
716 | ctx.sig = sig; | |
717 | else | |
718 | { | |
719 | pdkim_signature * n = ctx.sig; | |
720 | while (n->next) n = n->next; | |
721 | n->next = sig; | |
722 | } | |
80a47a2c | 723 | } |
9e70917d | 724 | } |
0b8f4f1a JH |
725 | if (!ctx.sig) |
726 | { | |
727 | DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n"); | |
728 | sigbuf = string_get(1); /* return a zero-len string */ | |
729 | goto CLEANUP; | |
730 | } | |
80a47a2c | 731 | |
d011368a | 732 | if (prefix && (pdkim_rc = pdkim_feed(&ctx, prefix, Ustrlen(prefix))) != PDKIM_OK) |
0b8f4f1a | 733 | goto pk_bad; |
80a47a2c | 734 | |
9e70917d JH |
735 | if (lseek(fd, off, SEEK_SET) < 0) |
736 | sread = -1; | |
737 | else | |
738 | while ((sread = read(fd, &buf, sizeof(buf))) > 0) | |
739 | if ((pdkim_rc = pdkim_feed(&ctx, buf, sread)) != PDKIM_OK) | |
740 | goto pk_bad; | |
80a47a2c | 741 | |
9e70917d JH |
742 | /* Handle failed read above. */ |
743 | if (sread == -1) | |
744 | { | |
745 | debug_printf("DKIM: Error reading -K file.\n"); | |
746 | save_errno = errno; | |
747 | goto bad; | |
80a47a2c | 748 | } |
a8e1eeba | 749 | |
9e70917d JH |
750 | /* Build string of headers, one per signature */ |
751 | ||
752 | if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK) | |
753 | goto pk_bad; | |
754 | ||
acec9514 JH |
755 | for (sigbuf = NULL; sig; sig = sig->next) |
756 | sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n"); | |
9e70917d | 757 | |
1cfe5c1c | 758 | CLEANUP: |
0b8f4f1a | 759 | (void) string_from_gstring(sigbuf); |
f7302073 JH |
760 | store_pool = old_pool; |
761 | errno = save_errno; | |
9e70917d | 762 | return sigbuf; |
f7302073 JH |
763 | |
764 | pk_bad: | |
765 | log_write(0, LOG_MAIN|LOG_PANIC, | |
766 | "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc)); | |
767 | bad: | |
9e70917d | 768 | sigbuf = NULL; |
f7302073 | 769 | goto CLEANUP; |
7c6ec81b JH |
770 | |
771 | expand_bad: | |
772 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand %s: %s", | |
773 | errwhen, expand_string_message); | |
774 | goto bad; | |
93f2d376 | 775 | } |
80a47a2c | 776 | |
dfbcb5ac JH |
777 | |
778 | ||
779 | ||
780 | gstring * | |
781 | authres_dkim(gstring * g) | |
782 | { | |
783 | pdkim_signature * sig; | |
784 | ||
785 | for (sig = dkim_signatures; sig; sig = sig->next) | |
786 | { | |
787 | g = string_catn(g, US";\\n\\tdkim=", 10); | |
788 | ||
789 | if (sig->verify_status & PDKIM_VERIFY_POLICY) | |
790 | g = string_append(g, 5, | |
791 | US"policy (", dkim_verify_status, US" - ", dkim_verify_reason, US")"); | |
792 | else switch(sig->verify_status) | |
793 | { | |
794 | case PDKIM_VERIFY_NONE: g = string_cat(g, US"none"); break; | |
795 | case PDKIM_VERIFY_INVALID: | |
796 | switch (sig->verify_ext_status) | |
797 | { | |
798 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
799 | g = string_cat(g, US"tmperror (pubkey unavailable)"); break; | |
800 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: | |
801 | g = string_cat(g, US"permerror (overlong public key record)"); break; | |
802 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: | |
803 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: | |
804 | g = string_cat(g, US"neutral (syntax error in public key record)"); | |
805 | break; | |
806 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: | |
807 | g = string_cat(g, US"neutral (signature tag missing or invalid)"); | |
808 | break; | |
809 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: | |
810 | g = string_cat(g, US"neutral (unsupported DKIM version)"); | |
811 | break; | |
812 | default: | |
813 | g = string_cat(g, US"permerror (unspecified problem)"); break; | |
814 | } | |
815 | break; | |
816 | case PDKIM_VERIFY_FAIL: | |
817 | switch (sig->verify_ext_status) | |
818 | { | |
819 | case PDKIM_VERIFY_FAIL_BODY: | |
820 | g = string_cat(g, | |
821 | US"fail (body hash mismatch; body probably modified in transit)"); | |
822 | break; | |
823 | case PDKIM_VERIFY_FAIL_MESSAGE: | |
824 | g = string_cat(g, | |
825 | US"fail (signature did not verify; headers probably modified in transit)"); | |
826 | break; | |
827 | default: | |
828 | g = string_cat(g, US"fail (unspecified reason)"); | |
829 | break; | |
830 | } | |
831 | break; | |
832 | case PDKIM_VERIFY_PASS: g = string_cat(g, US"pass"); break; | |
833 | default: g = string_cat(g, US"permerror"); break; | |
834 | } | |
835 | if (sig->domain) g = string_append(g, 2, US" header.d=", sig->domain); | |
836 | if (sig->identity) g = string_append(g, 2, US" header.i=", sig->identity); | |
837 | if (sig->selector) g = string_append(g, 2, US" header.s=", sig->selector); | |
838 | g = string_append(g, 2, US" header.a=", dkim_sig_to_a_tag(sig)); | |
839 | } | |
840 | return g; | |
841 | } | |
842 | ||
843 | ||
970424a5 JH |
844 | # endif /*!MACRO_PREDEF*/ |
845 | #endif /*!DISABLE_DKIM*/ |