Commit | Line | Data |
---|---|---|
2592e6c0 JH |
1 | /* |
2 | * PDKIM - a RFC4871 (DKIM) implementation | |
3 | * | |
9242a7e8 | 4 | * Copyright (C) 2017 Exim maintainers |
2592e6c0 | 5 | * |
d73e45df | 6 | * signing/verification interface |
2592e6c0 JH |
7 | */ |
8 | ||
9 | #include "../exim.h" | |
10 | ||
11 | #ifndef DISABLE_DKIM /* entire file */ | |
12 | ||
13 | #ifndef SUPPORT_TLS | |
14 | # error Need SUPPORT_TLS for DKIM | |
15 | #endif | |
16 | ||
17 | #include "crypt_ver.h" | |
9b2583c4 | 18 | #include "signing.h" |
2592e6c0 JH |
19 | |
20 | ||
21 | /******************************************************************************/ | |
d73e45df | 22 | #ifdef SIGN_GNUTLS |
286b9d5f JH |
23 | # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL 3 |
24 | ||
25 | ||
26 | /* Logging function which can be registered with | |
27 | * gnutls_global_set_log_function() | |
28 | * gnutls_global_set_log_level() 0..9 | |
29 | */ | |
30 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 | |
31 | static void | |
32 | exim_gnutls_logger_cb(int level, const char *message) | |
33 | { | |
34 | size_t len = strlen(message); | |
35 | if (len < 1) | |
36 | { | |
37 | DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); | |
38 | return; | |
39 | } | |
40 | DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, | |
41 | message[len-1] == '\n' ? "" : "\n"); | |
42 | } | |
43 | #endif | |
44 | ||
45 | ||
2592e6c0 JH |
46 | |
47 | void | |
9b2583c4 | 48 | exim_dkim_init(void) |
2592e6c0 | 49 | { |
286b9d5f JH |
50 | #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 |
51 | DEBUG(D_tls) | |
52 | { | |
53 | gnutls_global_set_log_function(exim_gnutls_logger_cb); | |
54 | /* arbitrarily chosen level; bump upto 9 for more */ | |
55 | gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); | |
56 | } | |
57 | #endif | |
2592e6c0 JH |
58 | } |
59 | ||
60 | ||
61 | /* accumulate data (gnutls-only). String to be appended must be nul-terminated. */ | |
acec9514 JH |
62 | gstring * |
63 | exim_dkim_data_append(gstring * g, uschar * s) | |
2592e6c0 | 64 | { |
acec9514 | 65 | return string_cat(g, s); |
2592e6c0 JH |
66 | } |
67 | ||
68 | ||
69 | ||
70 | /* import private key from PEM string in memory. | |
71 | Return: NULL for success, or an error string */ | |
72 | ||
73 | const uschar * | |
9b2583c4 | 74 | exim_dkim_signing_init(uschar * privkey_pem, es_ctx * sign_ctx) |
2592e6c0 | 75 | { |
286b9d5f JH |
76 | gnutls_datum_t k = { .data = privkey_pem, .size = Ustrlen(privkey_pem) }; |
77 | gnutls_x509_privkey_t x509_key; | |
2592e6c0 JH |
78 | int rc; |
79 | ||
286b9d5f JH |
80 | if ( (rc = gnutls_x509_privkey_init(&x509_key)) |
81 | || (rc = gnutls_x509_privkey_import(x509_key, &k, GNUTLS_X509_FMT_PEM)) | |
82 | || (rc = gnutls_privkey_init(&sign_ctx->key)) | |
83 | || (rc = gnutls_privkey_import_x509(sign_ctx->key, x509_key, 0)) | |
2592e6c0 | 84 | ) |
286b9d5f JH |
85 | return CUS gnutls_strerror(rc); |
86 | ||
87 | switch (rc = gnutls_privkey_get_pk_algorithm(sign_ctx->key, NULL)) | |
88 | { | |
89 | case GNUTLS_PK_RSA: sign_ctx->keytype = KEYTYPE_RSA; break; | |
90 | #ifdef SIGN_HAVE_ED25519 | |
91 | case GNUTLS_PK_EDDSA_ED25519: sign_ctx->keytype = KEYTYPE_ED25519; break; | |
92 | #endif | |
93 | default: return rc < 0 | |
94 | ? CUS gnutls_strerror(rc) | |
95 | : string_sprintf("Unhandled key type: %d '%s'", rc, gnutls_pk_get_name(rc)); | |
96 | } | |
2592e6c0 JH |
97 | |
98 | return NULL; | |
99 | } | |
100 | ||
101 | ||
102 | ||
103 | /* allocate mem for signature (when signing) */ | |
286b9d5f | 104 | /* hash & sign data. No way to do incremental. |
2592e6c0 JH |
105 | |
106 | Return: NULL for success, or an error string */ | |
107 | ||
108 | const uschar * | |
d73e45df | 109 | exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 110 | { |
286b9d5f | 111 | gnutls_datum_t k_data = { .data = data->data, .size = data->len }; |
d73e45df | 112 | gnutls_digest_algorithm_t dig; |
286b9d5f | 113 | gnutls_datum_t k_sig; |
2592e6c0 | 114 | int rc; |
2592e6c0 | 115 | |
d73e45df JH |
116 | switch (hash) |
117 | { | |
118 | case HASH_SHA1: dig = GNUTLS_DIG_SHA1; break; | |
119 | case HASH_SHA2_256: dig = GNUTLS_DIG_SHA256; break; | |
120 | case HASH_SHA2_512: dig = GNUTLS_DIG_SHA512; break; | |
121 | default: return US"nonhandled hash type"; | |
122 | } | |
123 | ||
286b9d5f JH |
124 | if ((rc = gnutls_privkey_sign_data(sign_ctx->key, dig, 0, &k_data, &k_sig))) |
125 | return CUS gnutls_strerror(rc); | |
2592e6c0 | 126 | |
286b9d5f | 127 | /* Don't care about deinit for the key; shortlived process */ |
2592e6c0 | 128 | |
286b9d5f JH |
129 | sig->data = k_sig.data; |
130 | sig->len = k_sig.size; | |
131 | return NULL; | |
2592e6c0 JH |
132 | } |
133 | ||
134 | ||
135 | ||
286b9d5f | 136 | /* import public key (from blob in memory) |
2592e6c0 JH |
137 | Return: NULL for success, or an error string */ |
138 | ||
139 | const uschar * | |
286b9d5f | 140 | exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx) |
2592e6c0 JH |
141 | { |
142 | gnutls_datum_t k; | |
143 | int rc; | |
144 | const uschar * ret = NULL; | |
145 | ||
d73e45df | 146 | gnutls_pubkey_init(&verify_ctx->key); |
286b9d5f JH |
147 | k.data = pubkey->data; |
148 | k.size = pubkey->len; | |
2592e6c0 | 149 | |
286b9d5f JH |
150 | switch(fmt) |
151 | { | |
152 | case KEYFMT_DER: | |
153 | if ((rc = gnutls_pubkey_import(verify_ctx->key, &k, GNUTLS_X509_FMT_DER))) | |
154 | ret = gnutls_strerror(rc); | |
155 | break; | |
156 | #ifdef SIGN_HAVE_ED25519 | |
157 | case KEYFMT_ED25519_BARE: | |
158 | if ((rc = gnutls_pubkey_import_ecc_raw(verify_ctx->key, | |
159 | GNUTLS_ECC_CURVE_ED25519, &k, NULL))) | |
160 | ret = gnutls_strerror(rc); | |
161 | break; | |
162 | #endif | |
163 | default: | |
164 | ret = US"pubkey format not handled"; | |
165 | break; | |
166 | } | |
2592e6c0 JH |
167 | return ret; |
168 | } | |
169 | ||
170 | ||
286b9d5f JH |
171 | /* verify signature (of hash if RSA sig, of data if EC sig. No way to do incremental) |
172 | (given pubkey & alleged sig) | |
2592e6c0 JH |
173 | Return: NULL for success, or an error string */ |
174 | ||
175 | const uschar * | |
d73e45df | 176 | exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig) |
2592e6c0 | 177 | { |
286b9d5f JH |
178 | gnutls_datum_t k = { .data = data_hash->data, .size = data_hash->len }; |
179 | gnutls_datum_t s = { .data = sig->data, .size = sig->len }; | |
2592e6c0 JH |
180 | int rc; |
181 | const uschar * ret = NULL; | |
182 | ||
286b9d5f JH |
183 | #ifdef SIGN_HAVE_ED25519 |
184 | if (verify_ctx->keytype == KEYTYPE_ED25519) | |
d73e45df | 185 | { |
286b9d5f JH |
186 | if ((rc = gnutls_pubkey_verify_data2(verify_ctx->key, |
187 | GNUTLS_SIGN_EDDSA_ED25519, 0, &k, &s)) < 0) | |
188 | ret = gnutls_strerror(rc); | |
d73e45df | 189 | } |
286b9d5f JH |
190 | else |
191 | #endif | |
192 | { | |
193 | gnutls_sign_algorithm_t algo; | |
194 | switch (hash) | |
195 | { | |
196 | case HASH_SHA1: algo = GNUTLS_SIGN_RSA_SHA1; break; | |
197 | case HASH_SHA2_256: algo = GNUTLS_SIGN_RSA_SHA256; break; | |
198 | case HASH_SHA2_512: algo = GNUTLS_SIGN_RSA_SHA512; break; | |
199 | default: return US"nonhandled hash type"; | |
200 | } | |
d73e45df | 201 | |
286b9d5f JH |
202 | if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->key, algo, 0, &k, &s)) < 0) |
203 | ret = gnutls_strerror(rc); | |
204 | } | |
2592e6c0 | 205 | |
d73e45df | 206 | gnutls_pubkey_deinit(verify_ctx->key); |
2592e6c0 JH |
207 | return ret; |
208 | } | |
209 | ||
210 | ||
211 | ||
212 | ||
d73e45df | 213 | #elif defined(SIGN_GCRYPT) |
2592e6c0 | 214 | /******************************************************************************/ |
d73e45df | 215 | /* This variant is used under pre-3.0.0 GnuTLS. Only rsa-sha1 and rsa-sha256 */ |
2592e6c0 JH |
216 | |
217 | ||
218 | /* Internal service routine: | |
219 | Read and move past an asn.1 header, checking class & tag, | |
220 | optionally returning the data-length */ | |
221 | ||
222 | static int | |
223 | as_tag(blob * der, uschar req_cls, long req_tag, long * alen) | |
224 | { | |
225 | int rc; | |
226 | uschar tag_class; | |
227 | int taglen; | |
228 | long tag, len; | |
229 | ||
286b9d5f JH |
230 | debug_printf_indent("as_tag: %02x %02x %02x %02x\n", |
231 | der->data[0], der->data[1], der->data[2], der->data[3]); | |
2592e6c0 JH |
232 | |
233 | if ((rc = asn1_get_tag_der(der->data++, der->len--, &tag_class, &taglen, &tag)) | |
234 | != ASN1_SUCCESS) | |
235 | return rc; | |
236 | ||
237 | if (tag_class != req_cls || tag != req_tag) return ASN1_ELEMENT_NOT_FOUND; | |
238 | ||
239 | if ((len = asn1_get_length_der(der->data, der->len, &taglen)) < 0) | |
240 | return ASN1_DER_ERROR; | |
241 | if (alen) *alen = len; | |
242 | ||
6e4aaa85 | 243 | /* debug_printf_indent("as_tag: tlen %d dlen %d\n", taglen, (int)len); */ |
2592e6c0 JH |
244 | |
245 | der->data += taglen; | |
246 | der->len -= taglen; | |
247 | return rc; | |
248 | } | |
249 | ||
250 | /* Internal service routine: | |
251 | Read and move over an asn.1 integer, setting an MPI to the value | |
252 | */ | |
253 | ||
254 | static uschar * | |
255 | as_mpi(blob * der, gcry_mpi_t * mpi) | |
256 | { | |
257 | long alen; | |
258 | int rc; | |
259 | gcry_error_t gerr; | |
260 | ||
286b9d5f JH |
261 | debug_printf_indent("%s\n", __FUNCTION__); |
262 | ||
2592e6c0 JH |
263 | /* integer; move past the header */ |
264 | if ((rc = as_tag(der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) | |
265 | return US asn1_strerror(rc); | |
266 | ||
267 | /* read to an MPI */ | |
268 | if ((gerr = gcry_mpi_scan(mpi, GCRYMPI_FMT_STD, der->data, alen, NULL))) | |
269 | return US gcry_strerror(gerr); | |
270 | ||
271 | /* move over the data */ | |
272 | der->data += alen; der->len -= alen; | |
273 | return NULL; | |
274 | } | |
275 | ||
276 | ||
277 | ||
278 | void | |
9b2583c4 | 279 | exim_dkim_init(void) |
2592e6c0 JH |
280 | { |
281 | /* Version check should be the very first call because it | |
282 | makes sure that important subsystems are initialized. */ | |
283 | if (!gcry_check_version (GCRYPT_VERSION)) | |
284 | { | |
285 | fputs ("libgcrypt version mismatch\n", stderr); | |
286 | exit (2); | |
287 | } | |
288 | ||
289 | /* We don't want to see any warnings, e.g. because we have not yet | |
290 | parsed program options which might be used to suppress such | |
291 | warnings. */ | |
292 | gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN); | |
293 | ||
294 | /* ... If required, other initialization goes here. Note that the | |
295 | process might still be running with increased privileges and that | |
296 | the secure memory has not been initialized. */ | |
297 | ||
298 | /* Allocate a pool of 16k secure memory. This make the secure memory | |
299 | available and also drops privileges where needed. */ | |
300 | gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0); | |
301 | ||
302 | /* It is now okay to let Libgcrypt complain when there was/is | |
303 | a problem with the secure memory. */ | |
304 | gcry_control (GCRYCTL_RESUME_SECMEM_WARN); | |
305 | ||
306 | /* ... If required, other initialization goes here. */ | |
307 | ||
308 | /* Tell Libgcrypt that initialization has completed. */ | |
309 | gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); | |
310 | ||
311 | return; | |
312 | } | |
313 | ||
314 | ||
315 | ||
316 | ||
317 | /* Accumulate data (gnutls-only). | |
318 | String to be appended must be nul-terminated. */ | |
319 | ||
acec9514 JH |
320 | gstring * |
321 | exim_dkim_data_append(gstring * g, uschar * s) | |
2592e6c0 | 322 | { |
acec9514 | 323 | return g; /*dummy*/ |
2592e6c0 JH |
324 | } |
325 | ||
326 | ||
327 | ||
328 | /* import private key from PEM string in memory. | |
286b9d5f | 329 | Only handles RSA keys. |
2592e6c0 JH |
330 | Return: NULL for success, or an error string */ |
331 | ||
332 | const uschar * | |
9b2583c4 | 333 | exim_dkim_signing_init(uschar * privkey_pem, es_ctx * sign_ctx) |
2592e6c0 JH |
334 | { |
335 | uschar * s1, * s2; | |
336 | blob der; | |
337 | long alen; | |
338 | int rc; | |
339 | ||
9b2583c4 | 340 | /*XXX will need extension to _spot_ as well as handle a |
286b9d5f JH |
341 | non-RSA key? I think... |
342 | So... this is not a PrivateKeyInfo - which would have a field | |
343 | identifying the keytype - PrivateKeyAlgorithmIdentifier - | |
344 | but a plain RSAPrivateKey (wrapped in PEM-headers. Can we | |
345 | use those as a type tag? What forms are there? "BEGIN EC PRIVATE KEY" (cf. ec(1ssl)) | |
346 | ||
347 | How does OpenSSL PEM_read_bio_PrivateKey() deal with it? | |
348 | gnutls_x509_privkey_import() ? | |
349 | */ | |
9b2583c4 | 350 | |
2592e6c0 JH |
351 | /* |
352 | * RSAPrivateKey ::= SEQUENCE | |
353 | * version Version, | |
354 | * modulus INTEGER, -- n | |
355 | * publicExponent INTEGER, -- e | |
356 | * privateExponent INTEGER, -- d | |
357 | * prime1 INTEGER, -- p | |
358 | * prime2 INTEGER, -- q | |
359 | * exponent1 INTEGER, -- d mod (p-1) | |
360 | * exponent2 INTEGER, -- d mod (q-1) | |
361 | * coefficient INTEGER, -- (inverse of q) mod p | |
362 | * otherPrimeInfos OtherPrimeInfos OPTIONAL | |
286b9d5f JH |
363 | |
364 | * ECPrivateKey ::= SEQUENCE { | |
365 | * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), | |
366 | * privateKey OCTET STRING, | |
367 | * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, | |
368 | * publicKey [1] BIT STRING OPTIONAL | |
369 | * } | |
370 | * Hmm, only 1 useful item, and not even an integer? Wonder how we might use it... | |
371 | ||
372 | - actually, gnutls_x509_privkey_import() appears to require a curve name parameter | |
373 | value for that is an OID? a local-only integer (it's an enum in GnuTLS)? | |
374 | ||
375 | ||
376 | Useful cmds: | |
377 | ssh-keygen -t ecdsa -f foo.privkey | |
378 | ssh-keygen -t ecdsa -b384 -f foo.privkey | |
379 | ssh-keygen -t ecdsa -b521 -f foo.privkey | |
380 | ssh-keygen -t ed25519 -f foo.privkey | |
381 | ||
382 | < foo openssl pkcs8 -in /dev/stdin -inform PEM -nocrypt -topk8 -outform DER | od -x | |
383 | ||
384 | openssl asn1parse -in foo -inform PEM -dump | |
385 | openssl asn1parse -in foo -inform PEM -dump -stroffset 24 (??) | |
386 | (not good for ed25519) | |
387 | ||
2592e6c0 JH |
388 | */ |
389 | ||
390 | if ( !(s1 = Ustrstr(CS privkey_pem, "-----BEGIN RSA PRIVATE KEY-----")) | |
391 | || !(s2 = Ustrstr(CS (s1+=31), "-----END RSA PRIVATE KEY-----" )) | |
392 | ) | |
393 | return US"Bad PEM wrapper"; | |
394 | ||
395 | *s2 = '\0'; | |
396 | ||
397 | if ((der.len = b64decode(s1, &der.data)) < 0) | |
398 | return US"Bad PEM-DER b64 decode"; | |
399 | ||
400 | /* untangle asn.1 */ | |
401 | ||
402 | /* sequence; just move past the header */ | |
403 | if ((rc = as_tag(&der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) | |
404 | != ASN1_SUCCESS) goto asn_err; | |
405 | ||
406 | /* integer version; move past the header, check is zero */ | |
407 | if ((rc = as_tag(&der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) | |
408 | goto asn_err; | |
409 | if (alen != 1 || *der.data != 0) | |
410 | return US"Bad version number"; | |
411 | der.data++; der.len--; | |
412 | ||
413 | if ( (s1 = as_mpi(&der, &sign_ctx->n)) | |
414 | || (s1 = as_mpi(&der, &sign_ctx->e)) | |
415 | || (s1 = as_mpi(&der, &sign_ctx->d)) | |
416 | || (s1 = as_mpi(&der, &sign_ctx->p)) | |
417 | || (s1 = as_mpi(&der, &sign_ctx->q)) | |
418 | || (s1 = as_mpi(&der, &sign_ctx->dp)) | |
419 | || (s1 = as_mpi(&der, &sign_ctx->dq)) | |
420 | || (s1 = as_mpi(&der, &sign_ctx->qp)) | |
421 | ) | |
422 | return s1; | |
423 | ||
349d0869 | 424 | #ifdef extreme_debug |
6e4aaa85 | 425 | DEBUG(D_acl) debug_printf_indent("rsa_signing_init:\n"); |
2592e6c0 JH |
426 | { |
427 | uschar * s; | |
428 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->n); | |
6e4aaa85 | 429 | debug_printf_indent(" N : %s\n", s); |
2592e6c0 | 430 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->e); |
6e4aaa85 | 431 | debug_printf_indent(" E : %s\n", s); |
2592e6c0 | 432 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->d); |
6e4aaa85 | 433 | debug_printf_indent(" D : %s\n", s); |
2592e6c0 | 434 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->p); |
6e4aaa85 | 435 | debug_printf_indent(" P : %s\n", s); |
2592e6c0 | 436 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->q); |
6e4aaa85 | 437 | debug_printf_indent(" Q : %s\n", s); |
2592e6c0 | 438 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dp); |
6e4aaa85 | 439 | debug_printf_indent(" DP: %s\n", s); |
2592e6c0 | 440 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dq); |
6e4aaa85 | 441 | debug_printf_indent(" DQ: %s\n", s); |
2592e6c0 | 442 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->qp); |
6e4aaa85 | 443 | debug_printf_indent(" QP: %s\n", s); |
2592e6c0 | 444 | } |
349d0869 | 445 | #endif |
286b9d5f JH |
446 | |
447 | sign_ctx->keytype = KEYTYPE_RSA; | |
2592e6c0 JH |
448 | return NULL; |
449 | ||
450 | asn_err: return US asn1_strerror(rc); | |
451 | } | |
452 | ||
453 | ||
454 | ||
455 | /* allocate mem for signature (when signing) */ | |
286b9d5f | 456 | /* sign already-hashed data. |
2592e6c0 JH |
457 | |
458 | Return: NULL for success, or an error string */ | |
459 | ||
460 | const uschar * | |
d73e45df | 461 | exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 462 | { |
349d0869 | 463 | char * sexp_hash; |
2592e6c0 JH |
464 | gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL; |
465 | gcry_mpi_t m_sig; | |
466 | uschar * errstr; | |
467 | gcry_error_t gerr; | |
468 | ||
9b2583c4 JH |
469 | /*XXX will need extension for hash types (though, possibly, should |
470 | be re-specced to not rehash but take an already-hashed value? Actually | |
d73e45df | 471 | current impl looks WRONG - it _is_ given a hash so should not be |
9b2583c4 JH |
472 | re-hashing. Has this been tested? |
473 | ||
474 | Will need extension for non-RSA sugning algos. */ | |
475 | ||
d73e45df JH |
476 | switch (hash) |
477 | { | |
349d0869 JH |
478 | case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break; |
479 | case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break; | |
d73e45df JH |
480 | default: return US"nonhandled hash type"; |
481 | } | |
482 | ||
2592e6c0 JH |
483 | #define SIGSPACE 128 |
484 | sig->data = store_get(SIGSPACE); | |
485 | ||
486 | if (gcry_mpi_cmp (sign_ctx->p, sign_ctx->q) > 0) | |
487 | { | |
488 | gcry_mpi_swap (sign_ctx->p, sign_ctx->q); | |
489 | gcry_mpi_invm (sign_ctx->qp, sign_ctx->p, sign_ctx->q); | |
490 | } | |
491 | ||
492 | if ( (gerr = gcry_sexp_build (&s_key, NULL, | |
493 | "(private-key (rsa (n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))", | |
494 | sign_ctx->n, sign_ctx->e, | |
495 | sign_ctx->d, sign_ctx->p, | |
496 | sign_ctx->q, sign_ctx->qp)) | |
349d0869 | 497 | || (gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash, |
2592e6c0 JH |
498 | (int) data->len, CS data->data)) |
499 | || (gerr = gcry_pk_sign (&s_sig, s_hash, s_key)) | |
500 | ) | |
501 | return US gcry_strerror(gerr); | |
502 | ||
503 | /* gcry_sexp_dump(s_sig); */ | |
504 | ||
505 | if ( !(s_sig = gcry_sexp_find_token(s_sig, "s", 0)) | |
506 | ) | |
507 | return US"no sig result"; | |
508 | ||
509 | m_sig = gcry_sexp_nth_mpi(s_sig, 1, GCRYMPI_FMT_USG); | |
510 | ||
349d0869 | 511 | #ifdef extreme_debug |
2592e6c0 JH |
512 | DEBUG(D_acl) |
513 | { | |
514 | uschar * s; | |
515 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig); | |
6e4aaa85 | 516 | debug_printf_indent(" SG: %s\n", s); |
2592e6c0 | 517 | } |
349d0869 | 518 | #endif |
2592e6c0 JH |
519 | |
520 | gerr = gcry_mpi_print(GCRYMPI_FMT_USG, sig->data, SIGSPACE, &sig->len, m_sig); | |
521 | if (gerr) | |
522 | { | |
6e4aaa85 | 523 | debug_printf_indent("signature conversion from MPI to buffer failed\n"); |
2592e6c0 JH |
524 | return US gcry_strerror(gerr); |
525 | } | |
526 | #undef SIGSPACE | |
527 | ||
528 | return NULL; | |
529 | } | |
530 | ||
531 | ||
286b9d5f | 532 | /* import public key (from blob in memory) |
2592e6c0 JH |
533 | Return: NULL for success, or an error string */ |
534 | ||
535 | const uschar * | |
286b9d5f | 536 | exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx) |
2592e6c0 JH |
537 | { |
538 | /* | |
539 | in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi() | |
540 | */ | |
541 | uschar tag_class; | |
542 | int taglen; | |
543 | long alen; | |
544 | int rc; | |
545 | uschar * errstr; | |
546 | gcry_error_t gerr; | |
547 | uschar * stage = US"S1"; | |
548 | ||
286b9d5f JH |
549 | if (fmt != KEYFMT_DER) return US"pubkey format not handled"; |
550 | ||
2592e6c0 JH |
551 | /* |
552 | sequence | |
553 | sequence | |
554 | OBJECT:rsaEncryption | |
555 | NULL | |
556 | BIT STRING:RSAPublicKey | |
557 | sequence | |
558 | INTEGER:Public modulus | |
559 | INTEGER:Public exponent | |
560 | ||
561 | openssl rsa -in aux-fixed/dkim/dkim.private -pubout -outform DER | od -t x1 | head; | |
562 | openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump; | |
563 | openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump -offset 22; | |
564 | */ | |
565 | ||
566 | /* sequence; just move past the header */ | |
286b9d5f | 567 | if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) |
2592e6c0 JH |
568 | != ASN1_SUCCESS) goto asn_err; |
569 | ||
570 | /* sequence; skip the entire thing */ | |
571 | DEBUG(D_acl) stage = US"S2"; | |
286b9d5f | 572 | if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen)) |
2592e6c0 | 573 | != ASN1_SUCCESS) goto asn_err; |
286b9d5f | 574 | pubkey->data += alen; pubkey->len -= alen; |
2592e6c0 JH |
575 | |
576 | ||
577 | /* bitstring: limit range to size of bitstring; | |
578 | move over header + content wrapper */ | |
579 | DEBUG(D_acl) stage = US"BS"; | |
286b9d5f | 580 | if ((rc = as_tag(pubkey, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS) |
2592e6c0 | 581 | goto asn_err; |
286b9d5f JH |
582 | pubkey->len = alen; |
583 | pubkey->data++; pubkey->len--; | |
2592e6c0 JH |
584 | |
585 | /* sequence; just move past the header */ | |
586 | DEBUG(D_acl) stage = US"S3"; | |
286b9d5f | 587 | if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) |
2592e6c0 JH |
588 | != ASN1_SUCCESS) goto asn_err; |
589 | ||
590 | /* read two integers */ | |
591 | DEBUG(D_acl) stage = US"MPI"; | |
286b9d5f JH |
592 | if ( (errstr = as_mpi(pubkey, &verify_ctx->n)) |
593 | || (errstr = as_mpi(pubkey, &verify_ctx->e)) | |
2592e6c0 JH |
594 | ) |
595 | return errstr; | |
596 | ||
349d0869 | 597 | #ifdef extreme_debug |
6e4aaa85 | 598 | DEBUG(D_acl) debug_printf_indent("rsa_verify_init:\n"); |
2592e6c0 JH |
599 | { |
600 | uschar * s; | |
601 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->n); | |
6e4aaa85 | 602 | debug_printf_indent(" N : %s\n", s); |
2592e6c0 | 603 | gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->e); |
6e4aaa85 | 604 | debug_printf_indent(" E : %s\n", s); |
2592e6c0 JH |
605 | } |
606 | ||
349d0869 | 607 | #endif |
2592e6c0 JH |
608 | return NULL; |
609 | ||
610 | asn_err: | |
611 | DEBUG(D_acl) return string_sprintf("%s: %s", stage, asn1_strerror(rc)); | |
612 | return US asn1_strerror(rc); | |
613 | } | |
614 | ||
615 | ||
286b9d5f JH |
616 | /* verify signature (of hash) |
617 | XXX though we appear to be doing a hash, too! | |
618 | (given pubkey & alleged sig) | |
2592e6c0 JH |
619 | Return: NULL for success, or an error string */ |
620 | ||
621 | const uschar * | |
d73e45df | 622 | exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig) |
2592e6c0 JH |
623 | { |
624 | /* | |
625 | cf. libgnutls 2.8.5 _wrap_gcry_pk_verify() | |
626 | */ | |
349d0869 | 627 | char * sexp_hash; |
2592e6c0 JH |
628 | gcry_mpi_t m_sig; |
629 | gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL; | |
630 | gcry_error_t gerr; | |
631 | uschar * stage; | |
632 | ||
349d0869 | 633 | /*XXX needs extension for SHA512 */ |
d73e45df JH |
634 | switch (hash) |
635 | { | |
349d0869 JH |
636 | case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break; |
637 | case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break; | |
638 | default: return US"nonhandled hash type"; | |
d73e45df JH |
639 | } |
640 | ||
2592e6c0 JH |
641 | if ( (stage = US"pkey sexp build", |
642 | gerr = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%m)(e%m)))", | |
643 | verify_ctx->n, verify_ctx->e)) | |
644 | || (stage = US"data sexp build", | |
349d0869 | 645 | gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash, |
2592e6c0 JH |
646 | (int) data_hash->len, CS data_hash->data)) |
647 | || (stage = US"sig mpi scan", | |
648 | gerr = gcry_mpi_scan(&m_sig, GCRYMPI_FMT_USG, sig->data, sig->len, NULL)) | |
649 | || (stage = US"sig sexp build", | |
650 | gerr = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", m_sig)) | |
651 | || (stage = US"verify", | |
652 | gerr = gcry_pk_verify (s_sig, s_hash, s_pkey)) | |
653 | ) | |
654 | { | |
6e4aaa85 | 655 | DEBUG(D_acl) debug_printf_indent("verify: error in stage '%s'\n", stage); |
2592e6c0 JH |
656 | return US gcry_strerror(gerr); |
657 | } | |
658 | ||
659 | if (s_sig) gcry_sexp_release (s_sig); | |
660 | if (s_hash) gcry_sexp_release (s_hash); | |
661 | if (s_pkey) gcry_sexp_release (s_pkey); | |
662 | gcry_mpi_release (m_sig); | |
663 | gcry_mpi_release (verify_ctx->n); | |
664 | gcry_mpi_release (verify_ctx->e); | |
665 | ||
666 | return NULL; | |
667 | } | |
668 | ||
669 | ||
670 | ||
671 | ||
d73e45df | 672 | #elif defined(SIGN_OPENSSL) |
2592e6c0 JH |
673 | /******************************************************************************/ |
674 | ||
675 | void | |
9b2583c4 | 676 | exim_dkim_init(void) |
2592e6c0 | 677 | { |
9e70917d | 678 | ERR_load_crypto_strings(); |
2592e6c0 JH |
679 | } |
680 | ||
681 | ||
286b9d5f JH |
682 | /* accumulate data (was gnutls-onl but now needed for OpenSSL non-EC too |
683 | because now using hash-and-sign interface) */ | |
acec9514 JH |
684 | gstring * |
685 | exim_dkim_data_append(gstring * g, uschar * s) | |
2592e6c0 | 686 | { |
286b9d5f | 687 | return string_cat(g, s); |
2592e6c0 JH |
688 | } |
689 | ||
690 | ||
691 | /* import private key from PEM string in memory. | |
692 | Return: NULL for success, or an error string */ | |
693 | ||
694 | const uschar * | |
9b2583c4 | 695 | exim_dkim_signing_init(uschar * privkey_pem, es_ctx * sign_ctx) |
2592e6c0 | 696 | { |
d73e45df | 697 | BIO * bp = BIO_new_mem_buf(privkey_pem, -1); |
2592e6c0 | 698 | |
d73e45df | 699 | if (!(sign_ctx->key = PEM_read_bio_PrivateKey(bp, NULL, NULL, NULL))) |
7845dbb3 | 700 | return US ERR_error_string(ERR_get_error(), NULL); |
286b9d5f JH |
701 | |
702 | sign_ctx->keytype = | |
703 | #ifdef SIGN_HAVE_ED25519 | |
704 | EVP_PKEY_type(EVP_PKEY_id(sign_ctx->key)) == EVP_PKEY_EC | |
705 | ? KEYTYPE_ED25519 : KEYTYPE_RSA; | |
706 | #else | |
707 | KEYTYPE_RSA; | |
708 | #endif | |
2592e6c0 JH |
709 | return NULL; |
710 | } | |
711 | ||
712 | ||
713 | ||
714 | /* allocate mem for signature (when signing) */ | |
286b9d5f | 715 | /* hash & sign data. Could be incremental |
2592e6c0 | 716 | |
9e70917d | 717 | Return: NULL for success with the signaature in the sig blob, or an error string */ |
2592e6c0 JH |
718 | |
719 | const uschar * | |
d73e45df | 720 | exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 721 | { |
d73e45df | 722 | const EVP_MD * md; |
286b9d5f | 723 | EVP_MD_CTX * ctx; |
d73e45df | 724 | size_t siglen; |
9b2583c4 | 725 | |
d73e45df JH |
726 | switch (hash) |
727 | { | |
728 | case HASH_SHA1: md = EVP_sha1(); break; | |
729 | case HASH_SHA2_256: md = EVP_sha256(); break; | |
730 | case HASH_SHA2_512: md = EVP_sha512(); break; | |
731 | default: return US"nonhandled hash type"; | |
732 | } | |
2592e6c0 | 733 | |
286b9d5f JH |
734 | /* Create the Message Digest Context */ |
735 | /*XXX renamed to EVP_MD_CTX_new() in 1.1.0 */ | |
736 | if( (ctx = EVP_MD_CTX_create()) | |
737 | ||
738 | /* Initialise the DigestSign operation */ | |
739 | && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0 | |
740 | ||
741 | /* Call update with the message */ | |
742 | && EVP_DigestSignUpdate(ctx, data->data, data->len) > 0 | |
743 | ||
744 | /* Finalise the DigestSign operation */ | |
745 | /* First call EVP_DigestSignFinal with a NULL sig parameter to obtain the length of the | |
746 | * signature. Length is returned in slen */ | |
747 | && EVP_DigestSignFinal(ctx, NULL, &siglen) > 0 | |
748 | ||
749 | /* Allocate memory for the signature based on size in slen */ | |
750 | && (sig->data = store_get(siglen)) | |
751 | ||
752 | /* Obtain the signature (slen could change here!) */ | |
753 | && EVP_DigestSignFinal(ctx, sig->data, &siglen) > 0 | |
d73e45df | 754 | ) |
2592e6c0 | 755 | { |
286b9d5f JH |
756 | EVP_MD_CTX_destroy(ctx); |
757 | sig->len = siglen; | |
758 | return NULL; | |
2592e6c0 JH |
759 | } |
760 | ||
286b9d5f | 761 | if (ctx) EVP_MD_CTX_destroy(ctx); |
7845dbb3 | 762 | return US ERR_error_string(ERR_get_error(), NULL); |
2592e6c0 JH |
763 | } |
764 | ||
765 | ||
766 | ||
286b9d5f | 767 | /* import public key (from blob in memory) |
9b2583c4 | 768 | Return: NULL for success, or an error string */ |
2592e6c0 JH |
769 | |
770 | const uschar * | |
286b9d5f | 771 | exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx) |
2592e6c0 | 772 | { |
286b9d5f JH |
773 | const uschar * s = pubkey->data; |
774 | uschar * ret = NULL; | |
2592e6c0 | 775 | |
286b9d5f JH |
776 | if (fmt != KEYFMT_DER) return US"pubkey format not handled"; |
777 | switch(fmt) | |
778 | { | |
779 | case KEYFMT_DER: | |
780 | /*XXX ok, this fails for EC: | |
781 | error:0609E09C:digital envelope routines:pkey_set_type:unsupported algorithm | |
782 | */ | |
783 | ||
784 | /*XXX hmm, we never free this */ | |
785 | if (!(verify_ctx->key = d2i_PUBKEY(NULL, &s, pubkey->len))) | |
786 | ret = US ERR_error_string(ERR_get_error(), NULL); | |
787 | break; | |
788 | #ifdef SIGN_HAVE_ED25519 | |
789 | case KEYFMT_ED25519_BARE: | |
790 | { | |
791 | BIGNUM * x; | |
792 | EC_KEY * eck; | |
793 | if ( !(x = BN_bin2bn(s, pubkey->len, NULL)) | |
794 | || !(eck = EC_KEY_new_by_curve_name(NID_ED25519)) | |
795 | || !EC_KEY_set_public_key_affine_coordinates(eck, x, NULL) | |
796 | || !(verify_ctx->key = EVP_PKEY_new()) | |
797 | || !EVP_PKEY_assign_EC_KEY(verify_ctx->key, eck) | |
798 | ) | |
799 | ret = US ERR_error_string(ERR_get_error(), NULL); | |
800 | } | |
801 | break; | |
802 | #endif | |
803 | default: | |
804 | ret = US"pubkey format not handled"; | |
805 | break; | |
806 | } | |
9b2583c4 | 807 | |
286b9d5f | 808 | return ret; |
2592e6c0 JH |
809 | } |
810 | ||
811 | ||
812 | ||
813 | ||
286b9d5f JH |
814 | /* verify signature (of hash) |
815 | (pre-EC coding; of data if "notyet" code, The latter could be incremental) | |
816 | (given pubkey & alleged sig) | |
2592e6c0 JH |
817 | Return: NULL for success, or an error string */ |
818 | ||
819 | const uschar * | |
286b9d5f | 820 | exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data, blob * sig) |
2592e6c0 | 821 | { |
d73e45df | 822 | const EVP_MD * md; |
286b9d5f JH |
823 | |
824 | /*XXX OpenSSL does not seem to have Ed25519 support yet. Reportedly BoringSSL does, | |
825 | but that's a nonstable API and not recommended (by its owner, Google) for external use. */ | |
2592e6c0 | 826 | |
d73e45df | 827 | switch (hash) |
2592e6c0 | 828 | { |
d73e45df JH |
829 | case HASH_SHA1: md = EVP_sha1(); break; |
830 | case HASH_SHA2_256: md = EVP_sha256(); break; | |
831 | case HASH_SHA2_512: md = EVP_sha512(); break; | |
832 | default: return US"nonhandled hash type"; | |
2592e6c0 | 833 | } |
d73e45df | 834 | |
286b9d5f JH |
835 | #ifdef notyet_SIGN_HAVE_ED25519 |
836 | { | |
837 | EVP_MD_CTX * ctx; | |
d73e45df | 838 | |
286b9d5f JH |
839 | /*XXX renamed to EVP_MD_CTX_new() in 1.1.0 */ |
840 | if ( | |
841 | (ctx = EVP_MD_CTX_create()) | |
842 | ||
843 | /* Initialize `key` with a public key */ | |
844 | && EVP_DigestVerifyInit(ctx, NULL, md, NULL, verify_ctx->key) > 0 | |
845 | ||
846 | /* add data to be hashed (call multiple times if needed) */ | |
847 | ||
848 | && EVP_DigestVerifyUpdate(ctx, data->data, data->len) > 0 | |
849 | ||
850 | /* finish off the hash and check the offered signature */ | |
851 | ||
852 | && EVP_DigestVerifyFinal(ctx, sig->data, sig->len) > 0 | |
853 | ) | |
854 | { | |
855 | EVP_MD_CTX_destroy(ctx); /* renamed to _free in 1.1.0 */ | |
856 | return NULL; | |
857 | } | |
858 | ||
859 | if (ctx) EVP_MD_CTX_free(ctx); | |
860 | return US ERR_error_string(ERR_get_error(), NULL); | |
861 | } | |
862 | #else | |
863 | { | |
864 | EVP_PKEY_CTX * ctx; | |
865 | ||
866 | if ( (ctx = EVP_PKEY_CTX_new(verify_ctx->key, NULL)) | |
867 | && EVP_PKEY_verify_init(ctx) > 0 | |
868 | && EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) > 0 | |
869 | && EVP_PKEY_CTX_set_signature_md(ctx, md) > 0 | |
870 | && EVP_PKEY_verify(ctx, sig->data, sig->len, | |
871 | data->data, data->len) == 1 | |
872 | ) | |
873 | { EVP_PKEY_CTX_free(ctx); return NULL; } | |
874 | ||
875 | if (ctx) EVP_PKEY_CTX_free(ctx); | |
876 | return US ERR_error_string(ERR_get_error(), NULL); | |
877 | } | |
878 | #endif | |
2592e6c0 JH |
879 | } |
880 | ||
881 | ||
d73e45df | 882 | |
2592e6c0 JH |
883 | #endif |
884 | /******************************************************************************/ | |
885 | ||
886 | #endif /*DISABLE_DKIM*/ | |
887 | /* End of File */ |