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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 | ||
617d3932 | 29 | pdkim_ctx dkim_sign_ctx; |
80a47a2c | 30 | |
ca9cb170 | 31 | int dkim_verify_oldpool; |
1cfe5c1c | 32 | pdkim_ctx *dkim_verify_ctx = NULL; |
1cfe5c1c | 33 | pdkim_signature *dkim_cur_sig = NULL; |
b9df1829 | 34 | static const uschar * dkim_collect_error = NULL; |
80a47a2c | 35 | |
64b67b65 JH |
36 | #define DKIM_MAX_SIGNATURES 20 |
37 | ||
d73e45df JH |
38 | |
39 | ||
362e4161 JH |
40 | /* Look up the DKIM record in DNS for the given hostname. |
41 | Will use the first found if there are multiple. | |
42 | The return string is tainted, having come from off-site. | |
d73e45df JH |
43 | */ |
44 | ||
617d3932 | 45 | uschar * |
fc2ba7b9 | 46 | dkim_exim_query_dns_txt(const uschar * name) |
1cfe5c1c | 47 | { |
8743d3ac | 48 | dns_answer * dnsa = store_get_dns_answer(); |
1cfe5c1c | 49 | dns_scan dnss; |
f3ebb786 | 50 | rmark reset_point = store_mark(); |
1eedc10f | 51 | gstring * g = NULL; |
80a47a2c | 52 | |
1cfe5c1c | 53 | lookup_dnssec_authenticated = NULL; |
362e4161 | 54 | if (dns_lookup(dnsa, name, T_TXT, NULL) != DNS_SUCCEED) |
1eedc10f | 55 | return NULL; /*XXX better error detail? logging? */ |
80a47a2c | 56 | |
1cfe5c1c | 57 | /* Search for TXT record */ |
80a47a2c | 58 | |
362e4161 | 59 | for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); |
1cfe5c1c | 60 | rr; |
362e4161 | 61 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) |
1cfe5c1c JH |
62 | if (rr->type == T_TXT) |
63 | { | |
80a47a2c | 64 | int rr_offset = 0; |
1cfe5c1c JH |
65 | |
66 | /* Copy record content to the answer buffer */ | |
67 | ||
68 | while (rr_offset < rr->size) | |
69 | { | |
70 | uschar len = rr->data[rr_offset++]; | |
1eedc10f JH |
71 | |
72 | g = string_catn(g, US(rr->data + rr_offset), len); | |
73 | if (g->ptr >= PDKIM_DNS_TXT_MAX_RECLEN) | |
74 | goto bad; | |
75 | ||
1cfe5c1c | 76 | rr_offset += len; |
4263f395 | 77 | } |
dd33c4e6 HSHR |
78 | |
79 | /* check if this looks like a DKIM record */ | |
d011368a | 80 | if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0) |
1eedc10f | 81 | { |
e59797e3 | 82 | gstring_release_unused(g); |
1eedc10f JH |
83 | return string_from_gstring(g); |
84 | } | |
85 | ||
86 | if (g) g->ptr = 0; /* overwrite previous record */ | |
80a47a2c | 87 | } |
80a47a2c | 88 | |
1eedc10f | 89 | bad: |
f3ebb786 | 90 | store_reset(reset_point); |
1eedc10f | 91 | return NULL; /*XXX better error detail? logging? */ |
80a47a2c TK |
92 | } |
93 | ||
94 | ||
2592e6c0 JH |
95 | void |
96 | dkim_exim_init(void) | |
97 | { | |
98 | pdkim_init(); | |
99 | } | |
100 | ||
101 | ||
ca9cb170 | 102 | |
1cfe5c1c | 103 | void |
e983e85a | 104 | dkim_exim_verify_init(BOOL dot_stuffing) |
1cfe5c1c | 105 | { |
ca9cb170 JH |
106 | /* There is a store-reset between header & body reception |
107 | so cannot use the main pool. Any allocs done by Exim | |
108 | memory-handling must use the perm pool. */ | |
109 | ||
110 | dkim_verify_oldpool = store_pool; | |
111 | store_pool = POOL_PERM; | |
112 | ||
1cfe5c1c | 113 | /* Free previous context if there is one */ |
80a47a2c | 114 | |
1cfe5c1c JH |
115 | if (dkim_verify_ctx) |
116 | pdkim_free_ctx(dkim_verify_ctx); | |
80a47a2c | 117 | |
1cfe5c1c | 118 | /* Create new context */ |
80a47a2c | 119 | |
e983e85a | 120 | dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing); |
64b67b65 | 121 | dkim_collect_input = dkim_verify_ctx ? DKIM_MAX_SIGNATURES : 0; |
b9df1829 | 122 | dkim_collect_error = NULL; |
ca9cb170 | 123 | |
584e96c6 JH |
124 | /* Start feed up with any cached data */ |
125 | receive_get_cache(); | |
126 | ||
ca9cb170 | 127 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
128 | } |
129 | ||
130 | ||
1cfe5c1c JH |
131 | void |
132 | dkim_exim_verify_feed(uschar * data, int len) | |
133 | { | |
f7302073 JH |
134 | int rc; |
135 | ||
ca9cb170 | 136 | store_pool = POOL_PERM; |
1cfe5c1c | 137 | if ( dkim_collect_input |
ef698bf6 | 138 | && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK) |
f7302073 | 139 | { |
b9df1829 | 140 | dkim_collect_error = pdkim_errstr(rc); |
f7302073 | 141 | log_write(0, LOG_MAIN, |
b9df1829 | 142 | "DKIM: validation error: %.100s", dkim_collect_error); |
64b67b65 | 143 | dkim_collect_input = 0; |
f7302073 | 144 | } |
ca9cb170 | 145 | store_pool = dkim_verify_oldpool; |
80a47a2c TK |
146 | } |
147 | ||
148 | ||
a79d8834 JH |
149 | /* Log the result for the given signature */ |
150 | static void | |
151 | dkim_exim_verify_log_sig(pdkim_signature * sig) | |
1cfe5c1c | 152 | { |
cc55f420 | 153 | gstring * logmsg; |
a79d8834 JH |
154 | uschar * s; |
155 | ||
cc55f420 JH |
156 | if (!sig) return; |
157 | ||
6678c382 | 158 | /* Remember the domain for the first pass result */ |
dfbcb5ac | 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 | ||
6678c382 JH |
167 | /* Rewrite the sig result if the ACL overrode it. This is only |
168 | needed because the DMARC code (sigh) peeks at the dkim sigs. | |
169 | Mark the sig for this having been done. */ | |
170 | ||
171 | if ( dkim_verify_status | |
172 | && ( dkim_verify_status != dkim_exim_expand_query(DKIM_VERIFY_STATUS) | |
173 | || dkim_verify_reason != dkim_exim_expand_query(DKIM_VERIFY_REASON) | |
174 | ) ) | |
175 | { /* overridden by ACL */ | |
176 | sig->verify_ext_status = -1; | |
177 | if (Ustrcmp(dkim_verify_status, US"fail") == 0) | |
178 | sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_FAIL; | |
179 | else if (Ustrcmp(dkim_verify_status, US"invalid") == 0) | |
180 | sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_INVALID; | |
181 | else if (Ustrcmp(dkim_verify_status, US"none") == 0) | |
182 | sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_NONE; | |
183 | else if (Ustrcmp(dkim_verify_status, US"pass") == 0) | |
184 | sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_PASS; | |
185 | else | |
186 | sig->verify_status = -1; | |
187 | } | |
188 | ||
2c47372f JH |
189 | if (!LOGGING(dkim_verbose)) return; |
190 | ||
6678c382 | 191 | |
aaaa94ea | 192 | logmsg = string_catn(NULL, US"DKIM: ", 6); |
a79d8834 JH |
193 | if (!(s = sig->domain)) s = US"<UNSET>"; |
194 | logmsg = string_append(logmsg, 2, "d=", s); | |
195 | if (!(s = sig->selector)) s = US"<UNSET>"; | |
196 | logmsg = string_append(logmsg, 2, " s=", s); | |
52f12a7c JH |
197 | logmsg = string_fmt_append(logmsg, " c=%s/%s a=%s b=" SIZE_T_FMT, |
198 | sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", | |
199 | sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", | |
200 | dkim_sig_to_a_tag(sig), | |
201 | (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : (size_t)0); | |
a79d8834 | 202 | if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s); |
52f12a7c JH |
203 | if (sig->created > 0) logmsg = string_fmt_append(logmsg, " t=%lu", |
204 | sig->created); | |
205 | if (sig->expires > 0) logmsg = string_fmt_append(logmsg, " x=%lu", | |
206 | sig->expires); | |
207 | if (sig->bodylength > -1) logmsg = string_fmt_append(logmsg, " l=%lu", | |
208 | sig->bodylength); | |
a79d8834 | 209 | |
dfbcb5ac JH |
210 | if (sig->verify_status & PDKIM_VERIFY_POLICY) |
211 | logmsg = string_append(logmsg, 5, | |
212 | US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]"); | |
213 | else | |
1cfe5c1c JH |
214 | switch (sig->verify_status) |
215 | { | |
216 | case PDKIM_VERIFY_NONE: | |
aaaa94ea | 217 | logmsg = string_cat(logmsg, US" [not verified]"); |
80a47a2c | 218 | break; |
1cfe5c1c JH |
219 | |
220 | case PDKIM_VERIFY_INVALID: | |
aaaa94ea | 221 | logmsg = string_cat(logmsg, US" [invalid - "); |
1cfe5c1c JH |
222 | switch (sig->verify_ext_status) |
223 | { | |
224 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
acec9514 | 225 | logmsg = string_cat(logmsg, |
aaaa94ea | 226 | US"public key record (currently?) unavailable]"); |
1cfe5c1c JH |
227 | break; |
228 | ||
229 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: | |
aaaa94ea | 230 | logmsg = string_cat(logmsg, US"overlong public key record]"); |
1cfe5c1c JH |
231 | break; |
232 | ||
df3def24 JH |
233 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: |
234 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: | |
aaaa94ea | 235 | logmsg = string_cat(logmsg, US"syntax error in public key record]"); |
1cfe5c1c | 236 | break; |
07eeb4df | 237 | |
a79d8834 | 238 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: |
aaaa94ea | 239 | logmsg = string_cat(logmsg, US"signature tag missing or invalid]"); |
a79d8834 | 240 | break; |
07eeb4df | 241 | |
a79d8834 | 242 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: |
aaaa94ea | 243 | logmsg = string_cat(logmsg, US"unsupported DKIM version]"); |
a79d8834 | 244 | break; |
1cfe5c1c JH |
245 | |
246 | default: | |
aaaa94ea | 247 | logmsg = string_cat(logmsg, US"unspecified problem]"); |
1cfe5c1c | 248 | } |
80a47a2c | 249 | break; |
1cfe5c1c JH |
250 | |
251 | case PDKIM_VERIFY_FAIL: | |
aaaa94ea | 252 | logmsg = string_cat(logmsg, US" [verification failed - "); |
1cfe5c1c JH |
253 | switch (sig->verify_ext_status) |
254 | { | |
255 | case PDKIM_VERIFY_FAIL_BODY: | |
acec9514 | 256 | logmsg = string_cat(logmsg, |
aaaa94ea | 257 | US"body hash mismatch (body probably modified in transit)]"); |
1cfe5c1c JH |
258 | break; |
259 | ||
260 | case PDKIM_VERIFY_FAIL_MESSAGE: | |
acec9514 | 261 | logmsg = string_cat(logmsg, |
aaaa94ea JH |
262 | US"signature did not verify " |
263 | "(headers probably modified in transit)]"); | |
dfbcb5ac | 264 | break; |
1cfe5c1c JH |
265 | |
266 | default: | |
aaaa94ea | 267 | logmsg = string_cat(logmsg, US"unspecified reason]"); |
1cfe5c1c | 268 | } |
80a47a2c | 269 | break; |
1cfe5c1c JH |
270 | |
271 | case PDKIM_VERIFY_PASS: | |
aaaa94ea | 272 | logmsg = string_cat(logmsg, US" [verification succeeded]"); |
80a47a2c TK |
273 | break; |
274 | } | |
a79d8834 | 275 | |
aaaa94ea | 276 | log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg)); |
a79d8834 JH |
277 | return; |
278 | } | |
279 | ||
80a47a2c | 280 | |
a79d8834 JH |
281 | /* Log a line for each signature */ |
282 | void | |
283 | dkim_exim_verify_log_all(void) | |
284 | { | |
d7978c0f JH |
285 | for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next) |
286 | dkim_exim_verify_log_sig(sig); | |
a79d8834 | 287 | } |
1cfe5c1c | 288 | |
80a47a2c | 289 | |
a79d8834 JH |
290 | void |
291 | dkim_exim_verify_finish(void) | |
292 | { | |
a79d8834 JH |
293 | int rc; |
294 | gstring * g = NULL; | |
286b9d5f | 295 | const uschar * errstr = NULL; |
a79d8834 JH |
296 | |
297 | store_pool = POOL_PERM; | |
298 | ||
299 | /* Delete eventual previous signature chain */ | |
300 | ||
301 | dkim_signers = NULL; | |
302 | dkim_signatures = NULL; | |
303 | ||
304 | if (dkim_collect_error) | |
305 | { | |
306 | log_write(0, LOG_MAIN, | |
307 | "DKIM: Error during validation, disabling signature verification: %.100s", | |
308 | dkim_collect_error); | |
8768d548 | 309 | f.dkim_disable_verify = TRUE; |
a79d8834 JH |
310 | goto out; |
311 | } | |
312 | ||
64b67b65 | 313 | dkim_collect_input = 0; |
a79d8834 JH |
314 | |
315 | /* Finish DKIM operation and fetch link to signatures chain */ | |
316 | ||
b4757e36 JH |
317 | rc = pdkim_feed_finish(dkim_verify_ctx, (pdkim_signature **)&dkim_signatures, |
318 | &errstr); | |
286b9d5f JH |
319 | if (rc != PDKIM_OK && errstr) |
320 | log_write(0, LOG_MAIN, "DKIM: validation error: %s", errstr); | |
a79d8834 JH |
321 | |
322 | /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ | |
323 | ||
d7978c0f | 324 | for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next) |
a79d8834 JH |
325 | { |
326 | if (sig->domain) g = string_append_listele(g, ':', sig->domain); | |
327 | if (sig->identity) g = string_append_listele(g, ':', sig->identity); | |
80a47a2c TK |
328 | } |
329 | ||
acec9514 JH |
330 | if (g) dkim_signers = g->s; |
331 | ||
ca9cb170 JH |
332 | out: |
333 | store_pool = dkim_verify_oldpool; | |
80a47a2c TK |
334 | } |
335 | ||
336 | ||
18067c75 JH |
337 | |
338 | /* Args as per dkim_exim_acl_run() below */ | |
339 | static int | |
340 | dkim_acl_call(uschar * id, gstring ** res_ptr, | |
341 | uschar ** user_msgptr, uschar ** log_msgptr) | |
342 | { | |
343 | int rc; | |
344 | DEBUG(D_receive) | |
345 | debug_printf("calling acl_smtp_dkim for dkim_cur_signer='%s'\n", id); | |
346 | ||
347 | rc = acl_check(ACL_WHERE_DKIM, NULL, acl_smtp_dkim, user_msgptr, log_msgptr); | |
348 | dkim_exim_verify_log_sig(dkim_cur_sig); | |
349 | *res_ptr = string_append_listele(*res_ptr, ':', dkim_verify_status); | |
350 | return rc; | |
351 | } | |
352 | ||
353 | ||
354 | ||
355 | /* For the given identity, run the DKIM ACL once for each matching signature. | |
356 | ||
357 | Arguments | |
358 | id Identity to look for in dkim signatures | |
359 | res_ptr ptr to growable string-list of status results, | |
360 | appended to per ACL run | |
361 | user_msgptr where to put a user error (for SMTP response) | |
362 | log_msgptr where to put a logging message (not for SMTP response) | |
363 | ||
364 | Returns: OK access is granted by an ACCEPT verb | |
365 | DISCARD access is granted by a DISCARD verb | |
366 | FAIL access is denied | |
367 | FAIL_DROP access is denied; drop the connection | |
368 | DEFER can't tell at the moment | |
369 | ERROR disaster | |
370 | */ | |
371 | ||
372 | int | |
373 | dkim_exim_acl_run(uschar * id, gstring ** res_ptr, | |
374 | uschar ** user_msgptr, uschar ** log_msgptr) | |
1cfe5c1c | 375 | { |
1cfe5c1c | 376 | uschar * cmp_val; |
18067c75 | 377 | int rc = -1; |
1cfe5c1c | 378 | |
cc55f420 JH |
379 | dkim_verify_status = US"none"; |
380 | dkim_verify_reason = US""; | |
1cfe5c1c JH |
381 | dkim_cur_signer = id; |
382 | ||
8768d548 | 383 | if (f.dkim_disable_verify || !id || !dkim_verify_ctx) |
18067c75 | 384 | return OK; |
1cfe5c1c | 385 | |
18067c75 | 386 | /* Find signatures to run ACL on */ |
1cfe5c1c | 387 | |
d7978c0f | 388 | for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next) |
1cfe5c1c JH |
389 | if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain) |
390 | && strcmpic(cmp_val, id) == 0 | |
391 | ) | |
392 | { | |
1cfe5c1c | 393 | /* The "dkim_domain" and "dkim_selector" expansion variables have |
18067c75 JH |
394 | related globals, since they are used in the signing code too. |
395 | Instead of inventing separate names for verification, we set | |
396 | them here. This is easy since a domain and selector is guaranteed | |
397 | to be in a signature. The other dkim_* expansion items are | |
398 | dynamically fetched from dkim_cur_sig at expansion time (see | |
b4757e36 | 399 | dkim_exim_expand_query() below). */ |
1cfe5c1c | 400 | |
18067c75 | 401 | dkim_cur_sig = sig; |
1cfe5c1c JH |
402 | dkim_signing_domain = US sig->domain; |
403 | dkim_signing_selector = US sig->selector; | |
dcd03763 | 404 | dkim_key_length = sig->sighash.len * 8; |
a79d8834 JH |
405 | |
406 | /* These two return static strings, so we can compare the addr | |
407 | later to see if the ACL overwrote them. Check that when logging */ | |
408 | ||
409 | dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS); | |
410 | dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON); | |
dd33c4e6 | 411 | |
18067c75 JH |
412 | if ((rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK) |
413 | return rc; | |
80a47a2c | 414 | } |
18067c75 JH |
415 | |
416 | if (rc != -1) | |
417 | return rc; | |
418 | ||
419 | /* No matching sig found. Call ACL once anyway. */ | |
420 | ||
421 | dkim_cur_sig = NULL; | |
422 | return dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr); | |
80a47a2c TK |
423 | } |
424 | ||
425 | ||
1cfe5c1c JH |
426 | static uschar * |
427 | dkim_exim_expand_defaults(int what) | |
428 | { | |
429 | switch (what) | |
430 | { | |
431 | case DKIM_ALGO: return US""; | |
432 | case DKIM_BODYLENGTH: return US"9999999999999"; | |
433 | case DKIM_CANON_BODY: return US""; | |
434 | case DKIM_CANON_HEADERS: return US""; | |
435 | case DKIM_COPIEDHEADERS: return US""; | |
436 | case DKIM_CREATED: return US"0"; | |
437 | case DKIM_EXPIRES: return US"9999999999999"; | |
438 | case DKIM_HEADERNAMES: return US""; | |
439 | case DKIM_IDENTITY: return US""; | |
440 | case DKIM_KEY_GRANULARITY: return US"*"; | |
441 | case DKIM_KEY_SRVTYPE: return US"*"; | |
442 | case DKIM_KEY_NOTES: return US""; | |
443 | case DKIM_KEY_TESTING: return US"0"; | |
444 | case DKIM_NOSUBDOMAINS: return US"0"; | |
445 | case DKIM_VERIFY_STATUS: return US"none"; | |
446 | case DKIM_VERIFY_REASON: return US""; | |
447 | default: return US""; | |
448 | } | |
449 | } | |
80a47a2c | 450 | |
80a47a2c | 451 | |
1cfe5c1c JH |
452 | uschar * |
453 | dkim_exim_expand_query(int what) | |
454 | { | |
8768d548 | 455 | if (!dkim_verify_ctx || f.dkim_disable_verify || !dkim_cur_sig) |
1cfe5c1c JH |
456 | return dkim_exim_expand_defaults(what); |
457 | ||
458 | switch (what) | |
459 | { | |
460 | case DKIM_ALGO: | |
d73e45df | 461 | return dkim_sig_to_a_tag(dkim_cur_sig); |
1cfe5c1c JH |
462 | |
463 | case DKIM_BODYLENGTH: | |
464 | return dkim_cur_sig->bodylength >= 0 | |
bb07bcd3 | 465 | ? string_sprintf("%ld", dkim_cur_sig->bodylength) |
1cfe5c1c JH |
466 | : dkim_exim_expand_defaults(what); |
467 | ||
468 | case DKIM_CANON_BODY: | |
469 | switch (dkim_cur_sig->canon_body) | |
470 | { | |
471 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
472 | case PDKIM_CANON_SIMPLE: | |
473 | default: return US"simple"; | |
80a47a2c | 474 | } |
1cfe5c1c JH |
475 | |
476 | case DKIM_CANON_HEADERS: | |
a79d8834 JH |
477 | switch (dkim_cur_sig->canon_headers) |
478 | { | |
479 | case PDKIM_CANON_RELAXED: return US"relaxed"; | |
480 | case PDKIM_CANON_SIMPLE: | |
481 | default: return US"simple"; | |
482 | } | |
1cfe5c1c JH |
483 | |
484 | case DKIM_COPIEDHEADERS: | |
485 | return dkim_cur_sig->copiedheaders | |
486 | ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what); | |
487 | ||
488 | case DKIM_CREATED: | |
489 | return dkim_cur_sig->created > 0 | |
bb07bcd3 | 490 | ? string_sprintf("%lu", dkim_cur_sig->created) |
1cfe5c1c JH |
491 | : dkim_exim_expand_defaults(what); |
492 | ||
493 | case DKIM_EXPIRES: | |
494 | return dkim_cur_sig->expires > 0 | |
bb07bcd3 | 495 | ? string_sprintf("%lu", dkim_cur_sig->expires) |
1cfe5c1c JH |
496 | : dkim_exim_expand_defaults(what); |
497 | ||
498 | case DKIM_HEADERNAMES: | |
499 | return dkim_cur_sig->headernames | |
2592e6c0 | 500 | ? dkim_cur_sig->headernames : dkim_exim_expand_defaults(what); |
1cfe5c1c JH |
501 | |
502 | case DKIM_IDENTITY: | |
503 | return dkim_cur_sig->identity | |
504 | ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what); | |
505 | ||
506 | case DKIM_KEY_GRANULARITY: | |
507 | return dkim_cur_sig->pubkey | |
508 | ? dkim_cur_sig->pubkey->granularity | |
509 | ? US dkim_cur_sig->pubkey->granularity | |
510 | : dkim_exim_expand_defaults(what) | |
511 | : dkim_exim_expand_defaults(what); | |
512 | ||
513 | case DKIM_KEY_SRVTYPE: | |
514 | return dkim_cur_sig->pubkey | |
515 | ? dkim_cur_sig->pubkey->srvtype | |
516 | ? US dkim_cur_sig->pubkey->srvtype | |
517 | : dkim_exim_expand_defaults(what) | |
518 | : dkim_exim_expand_defaults(what); | |
519 | ||
520 | case DKIM_KEY_NOTES: | |
521 | return dkim_cur_sig->pubkey | |
522 | ? dkim_cur_sig->pubkey->notes | |
523 | ? US dkim_cur_sig->pubkey->notes | |
524 | : dkim_exim_expand_defaults(what) | |
525 | : dkim_exim_expand_defaults(what); | |
526 | ||
527 | case DKIM_KEY_TESTING: | |
528 | return dkim_cur_sig->pubkey | |
529 | ? dkim_cur_sig->pubkey->testing | |
530 | ? US"1" | |
531 | : dkim_exim_expand_defaults(what) | |
532 | : dkim_exim_expand_defaults(what); | |
533 | ||
534 | case DKIM_NOSUBDOMAINS: | |
535 | return dkim_cur_sig->pubkey | |
536 | ? dkim_cur_sig->pubkey->no_subdomaining | |
537 | ? US"1" | |
538 | : dkim_exim_expand_defaults(what) | |
539 | : dkim_exim_expand_defaults(what); | |
540 | ||
541 | case DKIM_VERIFY_STATUS: | |
542 | switch (dkim_cur_sig->verify_status) | |
543 | { | |
544 | case PDKIM_VERIFY_INVALID: return US"invalid"; | |
545 | case PDKIM_VERIFY_FAIL: return US"fail"; | |
546 | case PDKIM_VERIFY_PASS: return US"pass"; | |
547 | case PDKIM_VERIFY_NONE: | |
548 | default: return US"none"; | |
80a47a2c | 549 | } |
80a47a2c | 550 | |
1cfe5c1c JH |
551 | case DKIM_VERIFY_REASON: |
552 | switch (dkim_cur_sig->verify_ext_status) | |
553 | { | |
554 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
555 | return US"pubkey_unavailable"; | |
df3def24 JH |
556 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax"; |
557 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax"; | |
1cfe5c1c JH |
558 | case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch"; |
559 | case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect"; | |
560 | } | |
80a47a2c | 561 | |
1cfe5c1c JH |
562 | default: |
563 | return US""; | |
80a47a2c TK |
564 | } |
565 | } | |
566 | ||
567 | ||
617d3932 JH |
568 | void |
569 | dkim_exim_sign_init(void) | |
570 | { | |
571 | int old_pool = store_pool; | |
572 | store_pool = POOL_MAIN; | |
573 | pdkim_init_context(&dkim_sign_ctx, FALSE, &dkim_exim_query_dns_txt); | |
574 | store_pool = old_pool; | |
575 | } | |
576 | ||
577 | ||
0b8f4f1a | 578 | /* Generate signatures for the given file. |
42055a33 | 579 | If a prefix is given, prepend it to the file for the calculations. |
0b8f4f1a JH |
580 | |
581 | Return: | |
582 | NULL: error; error string written | |
583 | string: signature header(s), or a zero-length string (not an error) | |
42055a33 JH |
584 | */ |
585 | ||
acec9514 | 586 | gstring * |
42055a33 JH |
587 | dkim_exim_sign(int fd, off_t off, uschar * prefix, |
588 | struct ob_dkim * dkim, const uschar ** errstr) | |
55414b25 | 589 | { |
617d3932 | 590 | const uschar * dkim_domain = NULL; |
1cfe5c1c | 591 | int sep = 0; |
acec9514 | 592 | gstring * seen_doms = NULL; |
9e70917d | 593 | pdkim_signature * sig; |
acec9514 | 594 | gstring * sigbuf; |
1cfe5c1c JH |
595 | int pdkim_rc; |
596 | int sread; | |
ef698bf6 | 597 | uschar buf[4096]; |
1cfe5c1c JH |
598 | int save_errno = 0; |
599 | int old_pool = store_pool; | |
7c6ec81b | 600 | uschar * errwhen; |
617d3932 | 601 | const uschar * s; |
1cfe5c1c | 602 | |
617d3932 JH |
603 | if (dkim->dot_stuffed) |
604 | dkim_sign_ctx.flags |= PDKIM_DOT_TERM; | |
1cfe5c1c | 605 | |
617d3932 | 606 | store_pool = POOL_MAIN; |
9e70917d | 607 | |
617d3932 | 608 | if ((s = dkim->dkim_domain) && !(dkim_domain = expand_cstring(s))) |
1cfe5c1c | 609 | /* expansion error, do not send message. */ |
7c6ec81b | 610 | { errwhen = US"dkim_domain"; goto expand_bad; } |
1cfe5c1c JH |
611 | |
612 | /* Set $dkim_domain expansion variable to each unique domain in list. */ | |
613 | ||
617d3932 JH |
614 | if (dkim_domain) |
615 | while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) | |
1cfe5c1c | 616 | { |
9e70917d JH |
617 | const uschar * dkim_sel; |
618 | int sel_sep = 0; | |
619 | ||
42055a33 | 620 | if (dkim_signing_domain[0] == '\0') |
1cfe5c1c JH |
621 | continue; |
622 | ||
623 | /* Only sign once for each domain, no matter how often it | |
624 | appears in the expanded list. */ | |
625 | ||
fe12ec88 | 626 | dkim_signing_domain = string_copylc(dkim_signing_domain); |
9e70917d JH |
627 | if (match_isinlist(dkim_signing_domain, CUSS &seen_doms, |
628 | 0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK) | |
629 | continue; | |
1cfe5c1c | 630 | |
acec9514 | 631 | seen_doms = string_append_listele(seen_doms, ':', dkim_signing_domain); |
1cfe5c1c | 632 | |
9e70917d JH |
633 | /* Set $dkim_selector expansion variable to each selector in list, |
634 | for this domain. */ | |
1cfe5c1c | 635 | |
9e70917d | 636 | if (!(dkim_sel = expand_string(dkim->dkim_selector))) |
7c6ec81b | 637 | { errwhen = US"dkim_selector"; goto expand_bad; } |
1cfe5c1c | 638 | |
9e70917d JH |
639 | while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep, |
640 | NULL, 0))) | |
1cfe5c1c | 641 | { |
9e70917d JH |
642 | uschar * dkim_canon_expanded; |
643 | int pdkim_canon; | |
644 | uschar * dkim_sign_headers_expanded = NULL; | |
645 | uschar * dkim_private_key_expanded; | |
646 | uschar * dkim_hash_expanded; | |
7c6ec81b | 647 | uschar * dkim_identity_expanded = NULL; |
2bc0f45e JH |
648 | uschar * dkim_timestamps_expanded = NULL; |
649 | unsigned long tval = 0, xval = 0; | |
80a47a2c | 650 | |
9e70917d | 651 | /* Get canonicalization to use */ |
1cfe5c1c | 652 | |
9e70917d JH |
653 | dkim_canon_expanded = dkim->dkim_canon |
654 | ? expand_string(dkim->dkim_canon) : US"relaxed"; | |
7c6ec81b JH |
655 | if (!dkim_canon_expanded) /* expansion error, do not send message. */ |
656 | { errwhen = US"dkim_canon"; goto expand_bad; } | |
1cfe5c1c | 657 | |
9e70917d JH |
658 | if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) |
659 | pdkim_canon = PDKIM_CANON_RELAXED; | |
660 | else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) | |
661 | pdkim_canon = PDKIM_CANON_SIMPLE; | |
662 | else | |
663 | { | |
664 | log_write(0, LOG_MAIN, | |
665 | "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", | |
666 | dkim_canon_expanded); | |
667 | pdkim_canon = PDKIM_CANON_RELAXED; | |
668 | } | |
1cfe5c1c | 669 | |
7c6ec81b JH |
670 | if ( dkim->dkim_sign_headers |
671 | && !(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) | |
672 | { errwhen = US"dkim_sign_header"; goto expand_bad; } | |
673 | /* else pass NULL, which means default header list */ | |
1cfe5c1c | 674 | |
9e70917d | 675 | /* Get private key to use. */ |
e983e85a | 676 | |
9e70917d | 677 | if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) |
7c6ec81b | 678 | { errwhen = US"dkim_private_key"; goto expand_bad; } |
80a47a2c | 679 | |
9e70917d JH |
680 | if ( Ustrlen(dkim_private_key_expanded) == 0 |
681 | || Ustrcmp(dkim_private_key_expanded, "0") == 0 | |
682 | || Ustrcmp(dkim_private_key_expanded, "false") == 0 | |
683 | ) | |
684 | continue; /* don't sign, but no error */ | |
685 | ||
617d3932 JH |
686 | if ( dkim_private_key_expanded[0] == '/' |
687 | && !(dkim_private_key_expanded = | |
688 | expand_file_big_buffer(dkim_private_key_expanded))) | |
689 | goto bad; | |
80a47a2c | 690 | |
9e70917d | 691 | if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash))) |
7c6ec81b JH |
692 | { errwhen = US"dkim_hash"; goto expand_bad; } |
693 | ||
694 | if (dkim->dkim_identity) | |
695 | if (!(dkim_identity_expanded = expand_string(dkim->dkim_identity))) | |
696 | { errwhen = US"dkim_identity"; goto expand_bad; } | |
697 | else if (!*dkim_identity_expanded) | |
698 | dkim_identity_expanded = NULL; | |
1cfe5c1c | 699 | |
2bc0f45e JH |
700 | if (dkim->dkim_timestamps) |
701 | if (!(dkim_timestamps_expanded = expand_string(dkim->dkim_timestamps))) | |
702 | { errwhen = US"dkim_timestamps"; goto expand_bad; } | |
703 | else | |
704 | xval = (tval = (unsigned long) time(NULL)) | |
48334568 | 705 | + strtoul(CCS dkim_timestamps_expanded, NULL, 10); |
2bc0f45e | 706 | |
617d3932 | 707 | if (!(sig = pdkim_init_sign(&dkim_sign_ctx, dkim_signing_domain, |
9e70917d JH |
708 | dkim_signing_selector, |
709 | dkim_private_key_expanded, | |
710 | dkim_hash_expanded, | |
711 | errstr | |
712 | ))) | |
713 | goto bad; | |
714 | dkim_private_key_expanded[0] = '\0'; | |
715 | ||
716 | pdkim_set_optional(sig, | |
717 | CS dkim_sign_headers_expanded, | |
27fd1318 | 718 | CS dkim_identity_expanded, |
9e70917d | 719 | pdkim_canon, |
2bc0f45e | 720 | pdkim_canon, -1, tval, xval); |
9e70917d | 721 | |
617d3932 | 722 | if (!pdkim_set_sig_bodyhash(&dkim_sign_ctx, sig)) |
cf1cce5e JH |
723 | goto bad; |
724 | ||
617d3932 JH |
725 | if (!dkim_sign_ctx.sig) /* link sig to context chain */ |
726 | dkim_sign_ctx.sig = sig; | |
9e70917d JH |
727 | else |
728 | { | |
617d3932 | 729 | pdkim_signature * n = dkim_sign_ctx.sig; |
9e70917d JH |
730 | while (n->next) n = n->next; |
731 | n->next = sig; | |
732 | } | |
80a47a2c | 733 | } |
9e70917d | 734 | } |
617d3932 JH |
735 | |
736 | /* We may need to carry on with the data-feed even if there are no DKIM sigs to | |
737 | produce, if some other package (eg. ARC) is signing. */ | |
738 | ||
739 | if (!dkim_sign_ctx.sig && !dkim->force_bodyhash) | |
0b8f4f1a JH |
740 | { |
741 | DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n"); | |
742 | sigbuf = string_get(1); /* return a zero-len string */ | |
0b8f4f1a | 743 | } |
9e70917d | 744 | else |
9e70917d | 745 | { |
617d3932 JH |
746 | if (prefix && (pdkim_rc = pdkim_feed(&dkim_sign_ctx, prefix, Ustrlen(prefix))) != PDKIM_OK) |
747 | goto pk_bad; | |
a8e1eeba | 748 | |
617d3932 JH |
749 | if (lseek(fd, off, SEEK_SET) < 0) |
750 | sread = -1; | |
751 | else | |
752 | while ((sread = read(fd, &buf, sizeof(buf))) > 0) | |
753 | if ((pdkim_rc = pdkim_feed(&dkim_sign_ctx, buf, sread)) != PDKIM_OK) | |
754 | goto pk_bad; | |
9e70917d | 755 | |
617d3932 JH |
756 | /* Handle failed read above. */ |
757 | if (sread == -1) | |
758 | { | |
759 | debug_printf("DKIM: Error reading -K file.\n"); | |
760 | save_errno = errno; | |
761 | goto bad; | |
762 | } | |
763 | ||
764 | /* Build string of headers, one per signature */ | |
9e70917d | 765 | |
617d3932 JH |
766 | if ((pdkim_rc = pdkim_feed_finish(&dkim_sign_ctx, &sig, errstr)) != PDKIM_OK) |
767 | goto pk_bad; | |
768 | ||
769 | if (!sig) | |
770 | { | |
771 | DEBUG(D_transport) debug_printf("DKIM: no signatures to use\n"); | |
772 | sigbuf = string_get(1); /* return a zero-len string */ | |
773 | } | |
774 | else for (sigbuf = NULL; sig; sig = sig->next) | |
775 | sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n"); | |
776 | } | |
9e70917d | 777 | |
1cfe5c1c | 778 | CLEANUP: |
0b8f4f1a | 779 | (void) string_from_gstring(sigbuf); |
f7302073 JH |
780 | store_pool = old_pool; |
781 | errno = save_errno; | |
9e70917d | 782 | return sigbuf; |
f7302073 JH |
783 | |
784 | pk_bad: | |
785 | log_write(0, LOG_MAIN|LOG_PANIC, | |
9fa4d5b4 | 786 | "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc)); |
f7302073 | 787 | bad: |
9e70917d | 788 | sigbuf = NULL; |
f7302073 | 789 | goto CLEANUP; |
7c6ec81b JH |
790 | |
791 | expand_bad: | |
9fa4d5b4 RJ |
792 | *errstr = string_sprintf("failed to expand %s: %s", |
793 | errwhen, expand_string_message); | |
794 | log_write(0, LOG_MAIN | LOG_PANIC, "%s", *errstr); | |
7c6ec81b | 795 | goto bad; |
93f2d376 | 796 | } |
80a47a2c | 797 | |
dfbcb5ac JH |
798 | |
799 | ||
800 | ||
801 | gstring * | |
802 | authres_dkim(gstring * g) | |
803 | { | |
0ae2cff6 | 804 | int start = 0; /* compiler quietening */ |
617d3932 JH |
805 | |
806 | DEBUG(D_acl) start = g->ptr; | |
dfbcb5ac | 807 | |
d7978c0f | 808 | for (pdkim_signature * sig = dkim_signatures; sig; sig = sig->next) |
dfbcb5ac | 809 | { |
e34f8ca2 | 810 | g = string_catn(g, US";\n\tdkim=", 8); |
dfbcb5ac JH |
811 | |
812 | if (sig->verify_status & PDKIM_VERIFY_POLICY) | |
813 | g = string_append(g, 5, | |
814 | US"policy (", dkim_verify_status, US" - ", dkim_verify_reason, US")"); | |
815 | else switch(sig->verify_status) | |
816 | { | |
817 | case PDKIM_VERIFY_NONE: g = string_cat(g, US"none"); break; | |
818 | case PDKIM_VERIFY_INVALID: | |
819 | switch (sig->verify_ext_status) | |
820 | { | |
821 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: | |
617d3932 | 822 | g = string_cat(g, US"tmperror (pubkey unavailable)\n\t\t"); break; |
dfbcb5ac | 823 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: |
617d3932 | 824 | g = string_cat(g, US"permerror (overlong public key record)\n\t\t"); break; |
dfbcb5ac JH |
825 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: |
826 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: | |
0e8aed8a | 827 | g = string_cat(g, US"neutral (public key record import problem)\n\t\t"); |
dfbcb5ac JH |
828 | break; |
829 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: | |
617d3932 | 830 | g = string_cat(g, US"neutral (signature tag missing or invalid)\n\t\t"); |
dfbcb5ac JH |
831 | break; |
832 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: | |
617d3932 | 833 | g = string_cat(g, US"neutral (unsupported DKIM version)\n\t\t"); |
dfbcb5ac JH |
834 | break; |
835 | default: | |
617d3932 | 836 | g = string_cat(g, US"permerror (unspecified problem)\n\t\t"); break; |
dfbcb5ac JH |
837 | } |
838 | break; | |
839 | case PDKIM_VERIFY_FAIL: | |
840 | switch (sig->verify_ext_status) | |
841 | { | |
842 | case PDKIM_VERIFY_FAIL_BODY: | |
843 | g = string_cat(g, | |
617d3932 | 844 | US"fail (body hash mismatch; body probably modified in transit)\n\t\t"); |
dfbcb5ac JH |
845 | break; |
846 | case PDKIM_VERIFY_FAIL_MESSAGE: | |
847 | g = string_cat(g, | |
617d3932 | 848 | US"fail (signature did not verify; headers probably modified in transit)\n\t\t"); |
dfbcb5ac JH |
849 | break; |
850 | default: | |
617d3932 | 851 | g = string_cat(g, US"fail (unspecified reason)\n\t\t"); |
dfbcb5ac JH |
852 | break; |
853 | } | |
854 | break; | |
855 | case PDKIM_VERIFY_PASS: g = string_cat(g, US"pass"); break; | |
856 | default: g = string_cat(g, US"permerror"); break; | |
857 | } | |
858 | if (sig->domain) g = string_append(g, 2, US" header.d=", sig->domain); | |
859 | if (sig->identity) g = string_append(g, 2, US" header.i=", sig->identity); | |
860 | if (sig->selector) g = string_append(g, 2, US" header.s=", sig->selector); | |
861 | g = string_append(g, 2, US" header.a=", dkim_sig_to_a_tag(sig)); | |
862 | } | |
617d3932 JH |
863 | |
864 | DEBUG(D_acl) | |
865 | if (g->ptr == start) | |
866 | debug_printf("DKIM: no authres\n"); | |
867 | else | |
868 | debug_printf("DKIM: authres '%.*s'\n", g->ptr - start - 3, g->s + start + 3); | |
dfbcb5ac JH |
869 | return g; |
870 | } | |
871 | ||
872 | ||
970424a5 JH |
873 | # endif /*!MACRO_PREDEF*/ |
874 | #endif /*!DISABLE_DKIM*/ |