crypto/asymmetric_keys/pkcs7_parser.c

   1 /* PKCS#7 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) "PKCS7: "fmt
  13 #include <linux/kernel.h>
  14 #include <linux/export.h>
  15 #include <linux/slab.h>
  16 #include <linux/err.h>
  17 #include <linux/oid_registry.h>
  18 #include "public_key.h"
  19 #include "pkcs7_parser.h"
  20 #include "pkcs7-asn1.h"
  21
  22 struct pkcs7_parse_context {
  23         struct pkcs7_message    *msg;           /* Message being constructed */
  24         struct pkcs7_signed_info *sinfo;        /* SignedInfo being constructed */
  25         struct pkcs7_signed_info **ppsinfo;
  26         struct x509_certificate *certs;         /* Certificate cache */
  27         struct x509_certificate **ppcerts;
  28         unsigned long   data;                   /* Start of data */
  29         enum OID        last_oid;               /* Last OID encountered */
  30         unsigned        x509_index;
  31         unsigned        sinfo_index;
  32         const void      *raw_serial;
  33         unsigned        raw_serial_size;
  34         unsigned        raw_issuer_size;
  35         const void      *raw_issuer;
  36 };
  37
  38 /*
  39  * Free a signed information block.
  40  */
  41 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
  42 {
  43         if (sinfo) {
  44                 mpi_free(sinfo->sig.mpi[0]);
  45                 kfree(sinfo->sig.digest);
  46                 kfree(sinfo->signing_cert_id);
  47                 kfree(sinfo);
  48         }
  49 }
  50
  51 /**
  52  * pkcs7_free_message - Free a PKCS#7 message
  53  * @pkcs7: The PKCS#7 message to free
  54  */
  55 void pkcs7_free_message(struct pkcs7_message *pkcs7)
  56 {
  57         struct x509_certificate *cert;
  58         struct pkcs7_signed_info *sinfo;
  59
  60         if (pkcs7) {
  61                 while (pkcs7->certs) {
  62                         cert = pkcs7->certs;
  63                         pkcs7->certs = cert->next;
  64                         x509_free_certificate(cert);
  65                 }
  66                 while (pkcs7->crl) {
  67                         cert = pkcs7->crl;
  68                         pkcs7->crl = cert->next;
  69                         x509_free_certificate(cert);
  70                 }
  71                 while (pkcs7->signed_infos) {
  72                         sinfo = pkcs7->signed_infos;
  73                         pkcs7->signed_infos = sinfo->next;
  74                         pkcs7_free_signed_info(sinfo);
  75                 }
  76                 kfree(pkcs7);
  77         }
  78 }
  79 EXPORT_SYMBOL_GPL(pkcs7_free_message);
  80
  81 /**
  82  * pkcs7_parse_message - Parse a PKCS#7 message
  83  * @data: The raw binary ASN.1 encoded message to be parsed
  84  * @datalen: The size of the encoded message
  85  */
  86 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
  87 {
  88         struct pkcs7_parse_context *ctx;
  89         struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
  90         int ret;
  91
  92         ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
  93         if (!ctx)
  94                 goto out_no_ctx;
  95         ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
  96         if (!ctx->msg)
  97                 goto out_no_msg;
  98         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
  99         if (!ctx->sinfo)
 100                 goto out_no_sinfo;
 101
 102         ctx->data = (unsigned long)data;
 103         ctx->ppcerts = &ctx->certs;
 104         ctx->ppsinfo = &ctx->msg->signed_infos;
 105
 106         /* Attempt to decode the signature */
 107         ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
 108         if (ret < 0) {
 109                 msg = ERR_PTR(ret);
 110                 goto out;
 111         }
 112
 113         msg = ctx->msg;
 114         ctx->msg = NULL;
 115
 116 out:
 117         while (ctx->certs) {
 118                 struct x509_certificate *cert = ctx->certs;
 119                 ctx->certs = cert->next;
 120                 x509_free_certificate(cert);
 121         }
 122         pkcs7_free_signed_info(ctx->sinfo);
 123 out_no_sinfo:
 124         pkcs7_free_message(ctx->msg);
 125 out_no_msg:
 126         kfree(ctx);
 127 out_no_ctx:
 128         return msg;
 129 }
 130 EXPORT_SYMBOL_GPL(pkcs7_parse_message);
 131
 132 /**
 133  * pkcs7_get_content_data - Get access to the PKCS#7 content
 134  * @pkcs7: The preparsed PKCS#7 message to access
 135  * @_data: Place to return a pointer to the data
 136  * @_data_len: Place to return the data length
 137  * @want_wrapper: True if the ASN.1 object header should be included in the data
 138  *
 139  * Get access to the data content of the PKCS#7 message, including, optionally,
 140  * the header of the ASN.1 object that contains it.  Returns -ENODATA if the
 141  * data object was missing from the message.
 142  */
 143 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
 144                            const void **_data, size_t *_data_len,
 145                            bool want_wrapper)
 146 {
 147         size_t wrapper;
 148
 149         if (!pkcs7->data)
 150                 return -ENODATA;
 151
 152         wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
 153         *_data = pkcs7->data - wrapper;
 154         *_data_len = pkcs7->data_len + wrapper;
 155         return 0;
 156 }
 157 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
 158
 159 /*
 160  * Note an OID when we find one for later processing when we know how
 161  * to interpret it.
 162  */
 163 int pkcs7_note_OID(void *context, size_t hdrlen,
 164                    unsigned char tag,
 165                    const void *value, size_t vlen)
 166 {
 167         struct pkcs7_parse_context *ctx = context;
 168
 169         ctx->last_oid = look_up_OID(value, vlen);
 170         if (ctx->last_oid == OID__NR) {
 171                 char buffer[50];
 172                 sprint_oid(value, vlen, buffer, sizeof(buffer));
 173                 printk("PKCS7: Unknown OID: [%lu] %s\n",
 174                        (unsigned long)value - ctx->data, buffer);
 175         }
 176         return 0;
 177 }
 178
 179 /*
 180  * Note the digest algorithm for the signature.
 181  */
 182 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
 183                                unsigned char tag,
 184                                const void *value, size_t vlen)
 185 {
 186         struct pkcs7_parse_context *ctx = context;
 187
 188         switch (ctx->last_oid) {
 189         case OID_md4:
 190                 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD4;
 191                 break;
 192         case OID_md5:
 193                 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD5;
 194                 break;
 195         case OID_sha1:
 196                 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA1;
 197                 break;
 198         case OID_sha256:
 199                 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA256;
 200                 break;
 201         default:
 202                 printk("Unsupported digest algo: %u\n", ctx->last_oid);
 203                 return -ENOPKG;
 204         }
 205         return 0;
 206 }
 207
 208 /*
 209  * Note the public key algorithm for the signature.
 210  */
 211 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
 212                              unsigned char tag,
 213                              const void *value, size_t vlen)
 214 {
 215         struct pkcs7_parse_context *ctx = context;
 216
 217         switch (ctx->last_oid) {
 218         case OID_rsaEncryption:
 219                 ctx->sinfo->sig.pkey_algo = PKEY_ALGO_RSA;
 220                 break;
 221         default:
 222                 printk("Unsupported pkey algo: %u\n", ctx->last_oid);
 223                 return -ENOPKG;
 224         }
 225         return 0;
 226 }
 227
 228 /*
 229  * Extract a certificate and store it in the context.
 230  */
 231 int pkcs7_extract_cert(void *context, size_t hdrlen,
 232                        unsigned char tag,
 233                        const void *value, size_t vlen)
 234 {
 235         struct pkcs7_parse_context *ctx = context;
 236         struct x509_certificate *x509;
 237
 238         if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
 239                 pr_debug("Cert began with tag %02x at %lu\n",
 240                          tag, (unsigned long)ctx - ctx->data);
 241                 return -EBADMSG;
 242         }
 243
 244         /* We have to correct for the header so that the X.509 parser can start
 245          * from the beginning.  Note that since X.509 stipulates DER, there
 246          * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
 247          * stipulates BER).
 248          */
 249         value -= hdrlen;
 250         vlen += hdrlen;
 251
 252         if (((u8*)value)[1] == 0x80)
 253                 vlen += 2; /* Indefinite length - there should be an EOC */
 254
 255         x509 = x509_cert_parse(value, vlen);
 256         if (IS_ERR(x509))
 257                 return PTR_ERR(x509);
 258
 259         x509->index = ++ctx->x509_index;
 260         pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
 261         pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
 262
 263         *ctx->ppcerts = x509;
 264         ctx->ppcerts = &x509->next;
 265         return 0;
 266 }
 267
 268 /*
 269  * Save the certificate list
 270  */
 271 int pkcs7_note_certificate_list(void *context, size_t hdrlen,
 272                                 unsigned char tag,
 273                                 const void *value, size_t vlen)
 274 {
 275         struct pkcs7_parse_context *ctx = context;
 276
 277         pr_devel("Got cert list (%02x)\n", tag);
 278
 279         *ctx->ppcerts = ctx->msg->certs;
 280         ctx->msg->certs = ctx->certs;
 281         ctx->certs = NULL;
 282         ctx->ppcerts = &ctx->certs;
 283         return 0;
 284 }
 285
 286 /*
 287  * Extract the data from the message and store that and its content type OID in
 288  * the context.
 289  */
 290 int pkcs7_note_data(void *context, size_t hdrlen,
 291                     unsigned char tag,
 292                     const void *value, size_t vlen)
 293 {
 294         struct pkcs7_parse_context *ctx = context;
 295
 296         pr_debug("Got data\n");
 297
 298         ctx->msg->data = value;
 299         ctx->msg->data_len = vlen;
 300         ctx->msg->data_hdrlen = hdrlen;
 301         ctx->msg->data_type = ctx->last_oid;
 302         return 0;
 303 }
 304
 305 /*
 306  * Parse authenticated attributes
 307  */
 308 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
 309                                       unsigned char tag,
 310                                       const void *value, size_t vlen)
 311 {
 312         struct pkcs7_parse_context *ctx = context;
 313
 314         pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 315
 316         switch (ctx->last_oid) {
 317         case OID_messageDigest:
 318                 if (tag != ASN1_OTS)
 319                         return -EBADMSG;
 320                 ctx->sinfo->msgdigest = value;
 321                 ctx->sinfo->msgdigest_len = vlen;
 322                 return 0;
 323         default:
 324                 return 0;
 325         }
 326 }
 327
 328 /*
 329  * Note the set of auth attributes for digestion purposes [RFC2315 9.3]
 330  */
 331 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
 332                                     unsigned char tag,
 333                                     const void *value, size_t vlen)
 334 {
 335         struct pkcs7_parse_context *ctx = context;
 336
 337         /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
 338         ctx->sinfo->authattrs = value - (hdrlen - 1);
 339         ctx->sinfo->authattrs_len = vlen + (hdrlen - 1);
 340         return 0;
 341 }
 342
 343 /*
 344  * Note the issuing certificate serial number
 345  */
 346 int pkcs7_sig_note_serial(void *context, size_t hdrlen,
 347                           unsigned char tag,
 348                           const void *value, size_t vlen)
 349 {
 350         struct pkcs7_parse_context *ctx = context;
 351         ctx->raw_serial = value;
 352         ctx->raw_serial_size = vlen;
 353         return 0;
 354 }
 355
 356 /*
 357  * Note the issuer's name
 358  */
 359 int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
 360                           unsigned char tag,
 361                           const void *value, size_t vlen)
 362 {
 363         struct pkcs7_parse_context *ctx = context;
 364         ctx->raw_issuer = value;
 365         ctx->raw_issuer_size = vlen;
 366         return 0;
 367 }
 368
 369 /*
 370  * Note the signature data
 371  */
 372 int pkcs7_sig_note_signature(void *context, size_t hdrlen,
 373                              unsigned char tag,
 374                              const void *value, size_t vlen)
 375 {
 376         struct pkcs7_parse_context *ctx = context;
 377         MPI mpi;
 378
 379         BUG_ON(ctx->sinfo->sig.pkey_algo != PKEY_ALGO_RSA);
 380
 381         mpi = mpi_read_raw_data(value, vlen);
 382         if (!mpi)
 383                 return -ENOMEM;
 384
 385         ctx->sinfo->sig.mpi[0] = mpi;
 386         ctx->sinfo->sig.nr_mpi = 1;
 387         return 0;
 388 }
 389
 390 /*
 391  * Note a signature information block
 392  */
 393 int pkcs7_note_signed_info(void *context, size_t hdrlen,
 394                            unsigned char tag,
 395                            const void *value, size_t vlen)
 396 {
 397         struct pkcs7_parse_context *ctx = context;
 398         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 399         struct asymmetric_key_id *kid;
 400
 401         /* Generate cert issuer + serial number key ID */
 402         kid = asymmetric_key_generate_id(ctx->raw_serial,
 403                                          ctx->raw_serial_size,
 404                                          ctx->raw_issuer,
 405                                          ctx->raw_issuer_size);
 406         if (IS_ERR(kid))
 407                 return PTR_ERR(kid);
 408
 409         sinfo->signing_cert_id = kid;
 410         sinfo->index = ++ctx->sinfo_index;
 411         *ctx->ppsinfo = sinfo;
 412         ctx->ppsinfo = &sinfo->next;
 413         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 414         if (!ctx->sinfo)
 415                 return -ENOMEM;
 416         return 0;
 417 }