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c26fd69f DH |
1 | /* X.509 certificate parser |
2 | * | |
3 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #define pr_fmt(fmt) "X.509: "fmt | |
13 | #include <linux/kernel.h> | |
ace0107a | 14 | #include <linux/export.h> |
c26fd69f DH |
15 | #include <linux/slab.h> |
16 | #include <linux/err.h> | |
17 | #include <linux/oid_registry.h> | |
18 | #include "public_key.h" | |
19 | #include "x509_parser.h" | |
20 | #include "x509-asn1.h" | |
21 | #include "x509_rsakey-asn1.h" | |
22 | ||
23 | struct x509_parse_context { | |
24 | struct x509_certificate *cert; /* Certificate being constructed */ | |
25 | unsigned long data; /* Start of data */ | |
26 | const void *cert_start; /* Start of cert content */ | |
27 | const void *key; /* Key data */ | |
28 | size_t key_size; /* Size of key data */ | |
29 | enum OID last_oid; /* Last OID encountered */ | |
30 | enum OID algo_oid; /* Algorithm OID */ | |
31 | unsigned char nr_mpi; /* Number of MPIs stored */ | |
32 | u8 o_size; /* Size of organizationName (O) */ | |
33 | u8 cn_size; /* Size of commonName (CN) */ | |
34 | u8 email_size; /* Size of emailAddress */ | |
35 | u16 o_offset; /* Offset of organizationName (O) */ | |
36 | u16 cn_offset; /* Offset of commonName (CN) */ | |
37 | u16 email_offset; /* Offset of emailAddress */ | |
38 | }; | |
39 | ||
40 | /* | |
41 | * Free an X.509 certificate | |
42 | */ | |
43 | void x509_free_certificate(struct x509_certificate *cert) | |
44 | { | |
45 | if (cert) { | |
46 | public_key_destroy(cert->pub); | |
47 | kfree(cert->issuer); | |
48 | kfree(cert->subject); | |
49 | kfree(cert->fingerprint); | |
50 | kfree(cert->authority); | |
b426beb6 DH |
51 | kfree(cert->sig.digest); |
52 | mpi_free(cert->sig.rsa.s); | |
c26fd69f DH |
53 | kfree(cert); |
54 | } | |
55 | } | |
ace0107a | 56 | EXPORT_SYMBOL_GPL(x509_free_certificate); |
c26fd69f DH |
57 | |
58 | /* | |
59 | * Parse an X.509 certificate | |
60 | */ | |
61 | struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) | |
62 | { | |
63 | struct x509_certificate *cert; | |
64 | struct x509_parse_context *ctx; | |
65 | long ret; | |
66 | ||
67 | ret = -ENOMEM; | |
68 | cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL); | |
69 | if (!cert) | |
70 | goto error_no_cert; | |
71 | cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL); | |
72 | if (!cert->pub) | |
73 | goto error_no_ctx; | |
74 | ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL); | |
75 | if (!ctx) | |
76 | goto error_no_ctx; | |
77 | ||
78 | ctx->cert = cert; | |
79 | ctx->data = (unsigned long)data; | |
80 | ||
81 | /* Attempt to decode the certificate */ | |
82 | ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen); | |
83 | if (ret < 0) | |
84 | goto error_decode; | |
85 | ||
86 | /* Decode the public key */ | |
87 | ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx, | |
88 | ctx->key, ctx->key_size); | |
89 | if (ret < 0) | |
90 | goto error_decode; | |
91 | ||
92 | kfree(ctx); | |
93 | return cert; | |
94 | ||
95 | error_decode: | |
96 | kfree(ctx); | |
97 | error_no_ctx: | |
98 | x509_free_certificate(cert); | |
99 | error_no_cert: | |
100 | return ERR_PTR(ret); | |
101 | } | |
ace0107a | 102 | EXPORT_SYMBOL_GPL(x509_cert_parse); |
c26fd69f DH |
103 | |
104 | /* | |
105 | * Note an OID when we find one for later processing when we know how | |
106 | * to interpret it. | |
107 | */ | |
108 | int x509_note_OID(void *context, size_t hdrlen, | |
109 | unsigned char tag, | |
110 | const void *value, size_t vlen) | |
111 | { | |
112 | struct x509_parse_context *ctx = context; | |
113 | ||
114 | ctx->last_oid = look_up_OID(value, vlen); | |
115 | if (ctx->last_oid == OID__NR) { | |
116 | char buffer[50]; | |
117 | sprint_oid(value, vlen, buffer, sizeof(buffer)); | |
cf75446e | 118 | pr_debug("Unknown OID: [%lu] %s\n", |
c26fd69f DH |
119 | (unsigned long)value - ctx->data, buffer); |
120 | } | |
121 | return 0; | |
122 | } | |
123 | ||
124 | /* | |
125 | * Save the position of the TBS data so that we can check the signature over it | |
126 | * later. | |
127 | */ | |
128 | int x509_note_tbs_certificate(void *context, size_t hdrlen, | |
129 | unsigned char tag, | |
130 | const void *value, size_t vlen) | |
131 | { | |
132 | struct x509_parse_context *ctx = context; | |
133 | ||
134 | pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n", | |
135 | hdrlen, tag, (unsigned long)value - ctx->data, vlen); | |
136 | ||
137 | ctx->cert->tbs = value - hdrlen; | |
138 | ctx->cert->tbs_size = vlen + hdrlen; | |
139 | return 0; | |
140 | } | |
141 | ||
142 | /* | |
143 | * Record the public key algorithm | |
144 | */ | |
145 | int x509_note_pkey_algo(void *context, size_t hdrlen, | |
146 | unsigned char tag, | |
147 | const void *value, size_t vlen) | |
148 | { | |
149 | struct x509_parse_context *ctx = context; | |
150 | ||
151 | pr_debug("PubKey Algo: %u\n", ctx->last_oid); | |
152 | ||
153 | switch (ctx->last_oid) { | |
154 | case OID_md2WithRSAEncryption: | |
155 | case OID_md3WithRSAEncryption: | |
156 | default: | |
157 | return -ENOPKG; /* Unsupported combination */ | |
158 | ||
159 | case OID_md4WithRSAEncryption: | |
3fe78ca2 | 160 | ctx->cert->sig.pkey_hash_algo = HASH_ALGO_MD5; |
b426beb6 | 161 | ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA; |
c26fd69f DH |
162 | break; |
163 | ||
164 | case OID_sha1WithRSAEncryption: | |
3fe78ca2 | 165 | ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1; |
b426beb6 | 166 | ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA; |
c26fd69f DH |
167 | break; |
168 | ||
169 | case OID_sha256WithRSAEncryption: | |
3fe78ca2 | 170 | ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256; |
b426beb6 | 171 | ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA; |
c26fd69f DH |
172 | break; |
173 | ||
174 | case OID_sha384WithRSAEncryption: | |
3fe78ca2 | 175 | ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384; |
b426beb6 | 176 | ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA; |
c26fd69f DH |
177 | break; |
178 | ||
179 | case OID_sha512WithRSAEncryption: | |
3fe78ca2 | 180 | ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512; |
b426beb6 | 181 | ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA; |
c26fd69f DH |
182 | break; |
183 | ||
184 | case OID_sha224WithRSAEncryption: | |
3fe78ca2 | 185 | ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224; |
b426beb6 | 186 | ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA; |
c26fd69f DH |
187 | break; |
188 | } | |
189 | ||
190 | ctx->algo_oid = ctx->last_oid; | |
191 | return 0; | |
192 | } | |
193 | ||
194 | /* | |
195 | * Note the whereabouts and type of the signature. | |
196 | */ | |
197 | int x509_note_signature(void *context, size_t hdrlen, | |
198 | unsigned char tag, | |
199 | const void *value, size_t vlen) | |
200 | { | |
201 | struct x509_parse_context *ctx = context; | |
202 | ||
203 | pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen); | |
204 | ||
205 | if (ctx->last_oid != ctx->algo_oid) { | |
206 | pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n", | |
207 | ctx->algo_oid, ctx->last_oid); | |
208 | return -EINVAL; | |
209 | } | |
210 | ||
b426beb6 DH |
211 | ctx->cert->raw_sig = value; |
212 | ctx->cert->raw_sig_size = vlen; | |
c26fd69f DH |
213 | return 0; |
214 | } | |
215 | ||
84aabd46 DH |
216 | /* |
217 | * Note the certificate serial number | |
218 | */ | |
219 | int x509_note_serial(void *context, size_t hdrlen, | |
220 | unsigned char tag, | |
221 | const void *value, size_t vlen) | |
222 | { | |
223 | struct x509_parse_context *ctx = context; | |
224 | ctx->cert->raw_serial = value; | |
225 | ctx->cert->raw_serial_size = vlen; | |
226 | return 0; | |
227 | } | |
228 | ||
c26fd69f DH |
229 | /* |
230 | * Note some of the name segments from which we'll fabricate a name. | |
231 | */ | |
232 | int x509_extract_name_segment(void *context, size_t hdrlen, | |
233 | unsigned char tag, | |
234 | const void *value, size_t vlen) | |
235 | { | |
236 | struct x509_parse_context *ctx = context; | |
237 | ||
238 | switch (ctx->last_oid) { | |
239 | case OID_commonName: | |
240 | ctx->cn_size = vlen; | |
241 | ctx->cn_offset = (unsigned long)value - ctx->data; | |
242 | break; | |
243 | case OID_organizationName: | |
244 | ctx->o_size = vlen; | |
245 | ctx->o_offset = (unsigned long)value - ctx->data; | |
246 | break; | |
247 | case OID_email_address: | |
248 | ctx->email_size = vlen; | |
249 | ctx->email_offset = (unsigned long)value - ctx->data; | |
250 | break; | |
251 | default: | |
252 | break; | |
253 | } | |
254 | ||
255 | return 0; | |
256 | } | |
257 | ||
258 | /* | |
259 | * Fabricate and save the issuer and subject names | |
260 | */ | |
261 | static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen, | |
262 | unsigned char tag, | |
263 | char **_name, size_t vlen) | |
264 | { | |
265 | const void *name, *data = (const void *)ctx->data; | |
266 | size_t namesize; | |
267 | char *buffer; | |
268 | ||
269 | if (*_name) | |
270 | return -EINVAL; | |
271 | ||
272 | /* Empty name string if no material */ | |
273 | if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) { | |
274 | buffer = kmalloc(1, GFP_KERNEL); | |
275 | if (!buffer) | |
276 | return -ENOMEM; | |
277 | buffer[0] = 0; | |
278 | goto done; | |
279 | } | |
280 | ||
281 | if (ctx->cn_size && ctx->o_size) { | |
282 | /* Consider combining O and CN, but use only the CN if it is | |
283 | * prefixed by the O, or a significant portion thereof. | |
284 | */ | |
285 | namesize = ctx->cn_size; | |
286 | name = data + ctx->cn_offset; | |
287 | if (ctx->cn_size >= ctx->o_size && | |
288 | memcmp(data + ctx->cn_offset, data + ctx->o_offset, | |
289 | ctx->o_size) == 0) | |
290 | goto single_component; | |
291 | if (ctx->cn_size >= 7 && | |
292 | ctx->o_size >= 7 && | |
293 | memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0) | |
294 | goto single_component; | |
295 | ||
296 | buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1, | |
297 | GFP_KERNEL); | |
298 | if (!buffer) | |
299 | return -ENOMEM; | |
300 | ||
301 | memcpy(buffer, | |
302 | data + ctx->o_offset, ctx->o_size); | |
303 | buffer[ctx->o_size + 0] = ':'; | |
304 | buffer[ctx->o_size + 1] = ' '; | |
305 | memcpy(buffer + ctx->o_size + 2, | |
306 | data + ctx->cn_offset, ctx->cn_size); | |
307 | buffer[ctx->o_size + 2 + ctx->cn_size] = 0; | |
308 | goto done; | |
309 | ||
310 | } else if (ctx->cn_size) { | |
311 | namesize = ctx->cn_size; | |
312 | name = data + ctx->cn_offset; | |
313 | } else if (ctx->o_size) { | |
314 | namesize = ctx->o_size; | |
315 | name = data + ctx->o_offset; | |
316 | } else { | |
317 | namesize = ctx->email_size; | |
318 | name = data + ctx->email_offset; | |
319 | } | |
320 | ||
321 | single_component: | |
322 | buffer = kmalloc(namesize + 1, GFP_KERNEL); | |
323 | if (!buffer) | |
324 | return -ENOMEM; | |
325 | memcpy(buffer, name, namesize); | |
326 | buffer[namesize] = 0; | |
327 | ||
328 | done: | |
329 | *_name = buffer; | |
330 | ctx->cn_size = 0; | |
331 | ctx->o_size = 0; | |
332 | ctx->email_size = 0; | |
333 | return 0; | |
334 | } | |
335 | ||
336 | int x509_note_issuer(void *context, size_t hdrlen, | |
337 | unsigned char tag, | |
338 | const void *value, size_t vlen) | |
339 | { | |
340 | struct x509_parse_context *ctx = context; | |
84aabd46 DH |
341 | ctx->cert->raw_issuer = value; |
342 | ctx->cert->raw_issuer_size = vlen; | |
c26fd69f DH |
343 | return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen); |
344 | } | |
345 | ||
346 | int x509_note_subject(void *context, size_t hdrlen, | |
347 | unsigned char tag, | |
348 | const void *value, size_t vlen) | |
349 | { | |
350 | struct x509_parse_context *ctx = context; | |
84aabd46 DH |
351 | ctx->cert->raw_subject = value; |
352 | ctx->cert->raw_subject_size = vlen; | |
c26fd69f DH |
353 | return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen); |
354 | } | |
355 | ||
356 | /* | |
357 | * Extract the data for the public key algorithm | |
358 | */ | |
359 | int x509_extract_key_data(void *context, size_t hdrlen, | |
360 | unsigned char tag, | |
361 | const void *value, size_t vlen) | |
362 | { | |
363 | struct x509_parse_context *ctx = context; | |
364 | ||
365 | if (ctx->last_oid != OID_rsaEncryption) | |
366 | return -ENOPKG; | |
367 | ||
67f7d60b DH |
368 | ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA; |
369 | ||
370 | /* Discard the BIT STRING metadata */ | |
c26fd69f DH |
371 | ctx->key = value + 1; |
372 | ctx->key_size = vlen - 1; | |
373 | return 0; | |
374 | } | |
375 | ||
376 | /* | |
377 | * Extract a RSA public key value | |
378 | */ | |
379 | int rsa_extract_mpi(void *context, size_t hdrlen, | |
380 | unsigned char tag, | |
381 | const void *value, size_t vlen) | |
382 | { | |
383 | struct x509_parse_context *ctx = context; | |
384 | MPI mpi; | |
385 | ||
386 | if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) { | |
387 | pr_err("Too many public key MPIs in certificate\n"); | |
388 | return -EBADMSG; | |
389 | } | |
390 | ||
391 | mpi = mpi_read_raw_data(value, vlen); | |
392 | if (!mpi) | |
393 | return -ENOMEM; | |
394 | ||
395 | ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi; | |
396 | return 0; | |
397 | } | |
398 | ||
04b00bdb CYL |
399 | /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */ |
400 | #define SEQ_TAG_KEYID (ASN1_CONT << 6) | |
401 | ||
c26fd69f DH |
402 | /* |
403 | * Process certificate extensions that are used to qualify the certificate. | |
404 | */ | |
405 | int x509_process_extension(void *context, size_t hdrlen, | |
406 | unsigned char tag, | |
407 | const void *value, size_t vlen) | |
408 | { | |
409 | struct x509_parse_context *ctx = context; | |
410 | const unsigned char *v = value; | |
411 | char *f; | |
412 | int i; | |
413 | ||
414 | pr_debug("Extension: %u\n", ctx->last_oid); | |
415 | ||
416 | if (ctx->last_oid == OID_subjectKeyIdentifier) { | |
417 | /* Get hold of the key fingerprint */ | |
418 | if (vlen < 3) | |
419 | return -EBADMSG; | |
420 | if (v[0] != ASN1_OTS || v[1] != vlen - 2) | |
421 | return -EBADMSG; | |
422 | v += 2; | |
423 | vlen -= 2; | |
424 | ||
425 | f = kmalloc(vlen * 2 + 1, GFP_KERNEL); | |
426 | if (!f) | |
427 | return -ENOMEM; | |
428 | for (i = 0; i < vlen; i++) | |
429 | sprintf(f + i * 2, "%02x", v[i]); | |
430 | pr_debug("fingerprint %s\n", f); | |
431 | ctx->cert->fingerprint = f; | |
432 | return 0; | |
433 | } | |
434 | ||
435 | if (ctx->last_oid == OID_authorityKeyIdentifier) { | |
04b00bdb CYL |
436 | size_t key_len; |
437 | ||
c26fd69f DH |
438 | /* Get hold of the CA key fingerprint */ |
439 | if (vlen < 5) | |
440 | return -EBADMSG; | |
04b00bdb CYL |
441 | |
442 | /* Authority Key Identifier must be a Constructed SEQUENCE */ | |
443 | if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5))) | |
c26fd69f | 444 | return -EBADMSG; |
c26fd69f | 445 | |
04b00bdb CYL |
446 | /* Authority Key Identifier is not indefinite length */ |
447 | if (unlikely(vlen == ASN1_INDEFINITE_LENGTH)) | |
448 | return -EBADMSG; | |
449 | ||
450 | if (vlen < ASN1_INDEFINITE_LENGTH) { | |
451 | /* Short Form length */ | |
452 | if (v[1] != vlen - 2 || | |
453 | v[2] != SEQ_TAG_KEYID || | |
454 | v[3] > vlen - 4) | |
455 | return -EBADMSG; | |
456 | ||
457 | key_len = v[3]; | |
458 | v += 4; | |
459 | } else { | |
460 | /* Long Form length */ | |
461 | size_t seq_len = 0; | |
462 | size_t sub = v[1] - ASN1_INDEFINITE_LENGTH; | |
463 | ||
464 | if (sub > 2) | |
465 | return -EBADMSG; | |
466 | ||
467 | /* calculate the length from subsequent octets */ | |
468 | v += 2; | |
469 | for (i = 0; i < sub; i++) { | |
470 | seq_len <<= 8; | |
471 | seq_len |= v[i]; | |
472 | } | |
473 | ||
474 | if (seq_len != vlen - 2 - sub || | |
475 | v[sub] != SEQ_TAG_KEYID || | |
476 | v[sub + 1] > vlen - 4 - sub) | |
477 | return -EBADMSG; | |
478 | ||
479 | key_len = v[sub + 1]; | |
480 | v += (sub + 2); | |
481 | } | |
482 | ||
483 | f = kmalloc(key_len * 2 + 1, GFP_KERNEL); | |
c26fd69f DH |
484 | if (!f) |
485 | return -ENOMEM; | |
04b00bdb | 486 | for (i = 0; i < key_len; i++) |
c26fd69f DH |
487 | sprintf(f + i * 2, "%02x", v[i]); |
488 | pr_debug("authority %s\n", f); | |
489 | ctx->cert->authority = f; | |
490 | return 0; | |
491 | } | |
492 | ||
493 | return 0; | |
494 | } | |
495 | ||
496 | /* | |
497 | * Record a certificate time. | |
498 | */ | |
a5752d11 | 499 | static int x509_note_time(struct tm *tm, size_t hdrlen, |
c26fd69f DH |
500 | unsigned char tag, |
501 | const unsigned char *value, size_t vlen) | |
502 | { | |
c26fd69f DH |
503 | const unsigned char *p = value; |
504 | ||
505 | #define dec2bin(X) ((X) - '0') | |
506 | #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; }) | |
507 | ||
508 | if (tag == ASN1_UNITIM) { | |
509 | /* UTCTime: YYMMDDHHMMSSZ */ | |
510 | if (vlen != 13) | |
511 | goto unsupported_time; | |
a5752d11 DH |
512 | tm->tm_year = DD2bin(p); |
513 | if (tm->tm_year >= 50) | |
514 | tm->tm_year += 1900; | |
c26fd69f | 515 | else |
a5752d11 | 516 | tm->tm_year += 2000; |
c26fd69f DH |
517 | } else if (tag == ASN1_GENTIM) { |
518 | /* GenTime: YYYYMMDDHHMMSSZ */ | |
519 | if (vlen != 15) | |
520 | goto unsupported_time; | |
a5752d11 | 521 | tm->tm_year = DD2bin(p) * 100 + DD2bin(p); |
c26fd69f DH |
522 | } else { |
523 | goto unsupported_time; | |
524 | } | |
525 | ||
a5752d11 DH |
526 | tm->tm_year -= 1900; |
527 | tm->tm_mon = DD2bin(p) - 1; | |
528 | tm->tm_mday = DD2bin(p); | |
529 | tm->tm_hour = DD2bin(p); | |
530 | tm->tm_min = DD2bin(p); | |
531 | tm->tm_sec = DD2bin(p); | |
c26fd69f DH |
532 | |
533 | if (*p != 'Z') | |
534 | goto unsupported_time; | |
535 | ||
c26fd69f DH |
536 | return 0; |
537 | ||
538 | unsupported_time: | |
539 | pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n", | |
540 | tag, (int)vlen, (int)vlen, value); | |
541 | return -EBADMSG; | |
542 | } | |
543 | ||
544 | int x509_note_not_before(void *context, size_t hdrlen, | |
545 | unsigned char tag, | |
546 | const void *value, size_t vlen) | |
547 | { | |
548 | struct x509_parse_context *ctx = context; | |
549 | return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen); | |
550 | } | |
551 | ||
552 | int x509_note_not_after(void *context, size_t hdrlen, | |
553 | unsigned char tag, | |
554 | const void *value, size_t vlen) | |
555 | { | |
556 | struct x509_parse_context *ctx = context; | |
557 | return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen); | |
558 | } |