lib/mscat/mscat_pkcs7.c

   1 /*
   2  * Copyright (c) 2016      Andreas Schneider <asn@samba.org>
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <errno.h>
  19 #include <stdint.h>
  20 #include <string.h>
  21 #include <sys/types.h>
  22 #include <sys/stat.h>
  23 #include <unistd.h>
  24
  25 #include <util/debug.h>
  26 #include <util/data_blob.h>
  27
  28 #include "mscat.h"
  29 #include "mscat_private.h"
  30
  31 #define PKCS7_CTL_OBJID                "1.3.6.1.4.1.311.10.1"
  32
  33 static int mscat_pkcs7_cleanup(struct mscat_pkcs7 *mp7)
  34 {
  35         if (mp7->c != NULL) {
  36                 gnutls_pkcs7_deinit(mp7->c);
  37         }
  38
  39         return 0;
  40 }
  41
  42 struct mscat_pkcs7 *mscat_pkcs7_init(TALLOC_CTX *mem_ctx)
  43 {
  44         struct mscat_pkcs7 *pkcs7;
  45         int rc;
  46
  47         pkcs7 = talloc_zero(mem_ctx, struct mscat_pkcs7);
  48         if (pkcs7 == NULL) {
  49                 return NULL;
  50         }
  51         talloc_set_destructor(pkcs7, mscat_pkcs7_cleanup);
  52
  53         rc = gnutls_pkcs7_init(&pkcs7->c);
  54         if (rc != 0) {
  55                 talloc_free(pkcs7);
  56                 return NULL;
  57         }
  58
  59         return pkcs7;
  60 }
  61
  62 static int mscat_read_file(TALLOC_CTX *mem_ctx,
  63                            const char *filename,
  64                            DATA_BLOB *pblob)
  65 {
  66         struct stat sb = {0};
  67         size_t alloc_size;
  68         size_t count;
  69         DATA_BLOB blob;
  70         FILE *fp;
  71         int rc;
  72
  73         fp = fopen(filename, "r");
  74         if (fp == NULL) {
  75                 return -1;
  76         }
  77
  78         rc = fstat(fileno(fp), &sb);
  79         if (rc != 0) {
  80                 goto error;
  81         }
  82
  83         if (!S_ISREG(sb.st_mode)) {
  84                 errno = EINVAL;
  85                 goto error;
  86         }
  87         if (SIZE_MAX - 1 < (unsigned long)sb.st_size) {
  88                 errno = ENOMEM;
  89                 goto error;
  90         }
  91         alloc_size = sb.st_size + 1;
  92
  93         blob = data_blob_talloc_zero(mem_ctx, alloc_size);
  94         if (blob.data == NULL) {
  95                 goto error;
  96         }
  97
  98         count = fread(blob.data, 1, blob.length, fp);
  99         if (count != blob.length) {
 100                 if (ferror(fp)) {
 101                         goto error;
 102                 }
 103         }
 104         blob.data[count] = '\0';
 105         blob.length = count;
 106         fclose(fp);
 107
 108         *pblob = blob;
 109
 110         return 0;
 111 error:
 112         data_blob_free(&blob);
 113         fclose(fp);
 114         return rc;
 115 }
 116
 117 int mscat_pkcs7_import_catfile(struct mscat_pkcs7 *mp7,
 118                                const char *catfile)
 119 {
 120         TALLOC_CTX *tmp_ctx;
 121         gnutls_datum_t mscat_data = {
 122                 .size = 0,
 123         };
 124         DATA_BLOB blob;
 125         int rc;
 126
 127         tmp_ctx = talloc_new(mp7);
 128         if (tmp_ctx == NULL) {
 129                 return -1;
 130         }
 131
 132         rc = mscat_read_file(tmp_ctx,
 133                              catfile,
 134                              &blob);
 135         if (rc == -1) {
 136                 DBG_ERR("Failed to read catalog file '%s' - %s",
 137                         catfile,
 138                         strerror(errno));
 139                 goto done;
 140         }
 141
 142         mscat_data.data = blob.data;
 143         mscat_data.size = blob.length;
 144
 145         rc = gnutls_pkcs7_import(mp7->c,
 146                                  &mscat_data,
 147                                  GNUTLS_X509_FMT_DER);
 148         if (rc < 0) {
 149                 DBG_ERR("Failed to import PKCS7 from '%s' - %s",
 150                         catfile,
 151                         gnutls_strerror(rc));
 152                 goto done;
 153         }
 154
 155         rc = 0;
 156 done:
 157         talloc_free(tmp_ctx);
 158         return rc;
 159 }
 160
 161 int mscat_pkcs7_verify(struct mscat_pkcs7 *mp7,
 162                        const char *ca_file)
 163 {
 164         TALLOC_CTX *tmp_ctx = NULL;
 165         gnutls_x509_trust_list_t tl = NULL;
 166         gnutls_datum_t ca_data;
 167         DATA_BLOB blob;
 168         uint32_t flags = 0;
 169         const char *oid;
 170         int count;
 171         int cmp;
 172         int rc;
 173         int i;
 174
 175         oid = gnutls_pkcs7_get_embedded_data_oid(mp7->c);
 176         if (oid == NULL) {
 177                 DBG_ERR("Failed to get oid - %s",
 178                         gnutls_strerror(errno));
 179                 return -1;
 180         }
 181
 182         cmp = strcmp(oid, PKCS7_CTL_OBJID);
 183         if (cmp != 0) {
 184                 DBG_ERR("Invalid oid in catalog file! oid: %s, expected: %s",
 185                         oid,
 186                         PKCS7_CTL_OBJID);
 187                 return -1;
 188         }
 189
 190         tmp_ctx = talloc_new(mp7);
 191         if (tmp_ctx == NULL) {
 192                 return -1;
 193         }
 194
 195         rc = gnutls_x509_trust_list_init(&tl,
 196                                          0); /* default size */
 197         if (rc != 0) {
 198                 DBG_ERR("Failed to create trust list - %s",
 199                         gnutls_strerror(rc));
 200                 goto done;
 201         }
 202
 203
 204         /* Load the system trust list */
 205         rc = gnutls_x509_trust_list_add_system_trust(tl, 0, 0);
 206         if (rc < 0) {
 207                 DBG_ERR("Failed to add system trust list - %s",
 208                         gnutls_strerror(rc));
 209                 goto done;
 210         }
 211         DBG_INFO("Loaded %d CAs", rc);
 212
 213         if (ca_file != NULL) {
 214                 rc = mscat_read_file(tmp_ctx,
 215                                      ca_file,
 216                                      &blob);
 217                 if (rc != 0) {
 218                         DBG_ERR("Failed to read CA file '%s' - %s",
 219                                 ca_file,
 220                                 strerror(errno));
 221                         goto done;
 222                 }
 223
 224                 ca_data.data = blob.data;
 225                 ca_data.size = blob.length;
 226
 227                 rc = gnutls_x509_trust_list_add_trust_mem(tl,
 228                                                           &ca_data,
 229                                                           NULL, /* crls */
 230                                                           GNUTLS_X509_FMT_DER,
 231                                                           0, /* tl_flags */
 232                                                           0); /* tl_vflags */
 233                 if (rc < 0) {
 234                         DBG_ERR("Failed to add '%s' to trust list - %s (%d)",
 235                                 ca_file,
 236                                 gnutls_strerror(rc),
 237                                 rc);
 238                         goto done;
 239                 }
 240                 DBG_INFO("Loaded %d additional CAs", rc);
 241         }
 242
 243         /*
 244          * Drivers often exist for quite some time, so it is possible that one
 245          * of the certificates in the trust list expired.
 246          * This is not a big deal, but we need to disable the time checks
 247          * or the verification will fail.
 248          */
 249         flags = GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS|
 250                 GNUTLS_VERIFY_DISABLE_TIME_CHECKS;
 251
 252 #if GNUTLS_VERSION_NUMBER >= 0x030600
 253         /* The "Microsoft Root Authority" certificate uses SHA1 */
 254         flags |= GNUTLS_VERIFY_ALLOW_SIGN_WITH_SHA1;
 255 #endif
 256
 257         count = gnutls_pkcs7_get_signature_count(mp7->c);
 258         if (count == 0) {
 259                 DBG_ERR("Failed to verify catalog file, no signatures found");
 260                 goto done;
 261         }
 262
 263         for (i = 0; i < count; i++) {
 264                 rc = gnutls_pkcs7_verify(mp7->c,
 265                                          tl,
 266                                          NULL, /* vdata */
 267                                          0,    /* vdata_size */
 268                                          i,    /* index */
 269                                          NULL, /* data */
 270                                          flags);   /* flags */
 271                 if (rc < 0) {
 272                         DBG_ERR("Failed to verify catalog file - %s (%d)",
 273                                 gnutls_strerror(rc),
 274                                 rc);
 275                         goto done;
 276                 }
 277         }
 278
 279         rc = 0;
 280 done:
 281         gnutls_x509_trust_list_deinit(tl, 1);
 282         talloc_free(tmp_ctx);
 283         return rc;
 284 }