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