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 = data_blob_null;
  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                 rc = -1;
  86                 goto error;
  87         }
  88         if (SIZE_MAX - 1 < (unsigned long)sb.st_size) {
  89                 errno = ENOMEM;
  90                 rc = -1;
  91                 goto error;
  92         }
  93         alloc_size = sb.st_size + 1;
  94
  95         blob = data_blob_talloc_zero(mem_ctx, alloc_size);
  96         if (blob.data == NULL) {
  97                 rc = -1;
  98                 goto error;
  99         }
 100
 101         count = fread(blob.data, 1, blob.length, fp);
 102         if (count != blob.length) {
 103                 if (ferror(fp)) {
 104                         rc = -1;
 105                         goto error;
 106                 }
 107         }
 108         blob.data[count] = '\0';
 109         blob.length = count;
 110         fclose(fp);
 111
 112         *pblob = blob;
 113
 114         return 0;
 115 error:
 116         data_blob_free(&blob);
 117         fclose(fp);
 118         return rc;
 119 }
 120
 121 int mscat_pkcs7_import_catfile(struct mscat_pkcs7 *mp7,
 122                                const char *catfile)
 123 {
 124         TALLOC_CTX *tmp_ctx;
 125         gnutls_datum_t mscat_data = {
 126                 .size = 0,
 127         };
 128         DATA_BLOB blob = {
 129                 .length = 0,
 130         };
 131         int rc;
 132
 133         tmp_ctx = talloc_new(mp7);
 134         if (tmp_ctx == NULL) {
 135                 return -1;
 136         }
 137
 138         rc = mscat_read_file(tmp_ctx,
 139                              catfile,
 140                              &blob);
 141         if (rc == -1) {
 142                 DBG_ERR("Failed to read catalog file '%s' - %s",
 143                         catfile,
 144                         strerror(errno));
 145                 goto done;
 146         }
 147
 148         mscat_data.data = blob.data;
 149         mscat_data.size = blob.length;
 150
 151         rc = gnutls_pkcs7_import(mp7->c,
 152                                  &mscat_data,
 153                                  GNUTLS_X509_FMT_DER);
 154         if (rc < 0) {
 155                 DBG_ERR("Failed to import PKCS7 from '%s' - %s",
 156                         catfile,
 157                         gnutls_strerror(rc));
 158                 goto done;
 159         }
 160
 161         rc = 0;
 162 done:
 163         talloc_free(tmp_ctx);
 164         return rc;
 165 }
 166
 167 int mscat_pkcs7_verify(struct mscat_pkcs7 *mp7,
 168                        const char *ca_file)
 169 {
 170         TALLOC_CTX *tmp_ctx = NULL;
 171         gnutls_x509_trust_list_t tl = NULL;
 172         gnutls_datum_t ca_data;
 173         DATA_BLOB blob = {
 174                 .length = 0,
 175         };
 176         uint32_t flags = 0;
 177         const char *oid;
 178         int count;
 179         int cmp;
 180         int rc;
 181         int i;
 182
 183         oid = gnutls_pkcs7_get_embedded_data_oid(mp7->c);
 184         if (oid == NULL) {
 185                 DBG_ERR("Failed to get oid - %s",
 186                         gnutls_strerror(errno));
 187                 return -1;
 188         }
 189
 190         cmp = strcmp(oid, PKCS7_CTL_OBJID);
 191         if (cmp != 0) {
 192                 DBG_ERR("Invalid oid in catalog file! oid: %s, expected: %s",
 193                         oid,
 194                         PKCS7_CTL_OBJID);
 195                 return -1;
 196         }
 197
 198         tmp_ctx = talloc_new(mp7);
 199         if (tmp_ctx == NULL) {
 200                 return -1;
 201         }
 202
 203         rc = gnutls_x509_trust_list_init(&tl,
 204                                          0); /* default size */
 205         if (rc != 0) {
 206                 DBG_ERR("Failed to create trust list - %s",
 207                         gnutls_strerror(rc));
 208                 goto done;
 209         }
 210
 211
 212         /* Load the system trust list */
 213         rc = gnutls_x509_trust_list_add_system_trust(tl, 0, 0);
 214         if (rc < 0) {
 215                 DBG_ERR("Failed to add system trust list - %s",
 216                         gnutls_strerror(rc));
 217                 goto done;
 218         }
 219         DBG_INFO("Loaded %d CAs", rc);
 220
 221         if (ca_file != NULL) {
 222                 rc = mscat_read_file(tmp_ctx,
 223                                      ca_file,
 224                                      &blob);
 225                 if (rc != 0) {
 226                         DBG_ERR("Failed to read CA file '%s' - %s",
 227                                 ca_file,
 228                                 strerror(errno));
 229                         goto done;
 230                 }
 231
 232                 ca_data.data = blob.data;
 233                 ca_data.size = blob.length;
 234
 235                 rc = gnutls_x509_trust_list_add_trust_mem(tl,
 236                                                           &ca_data,
 237                                                           NULL, /* crls */
 238                                                           GNUTLS_X509_FMT_DER,
 239                                                           0, /* tl_flags */
 240                                                           0); /* tl_vflags */
 241                 if (rc < 0) {
 242                         DBG_ERR("Failed to add '%s' to trust list - %s (%d)",
 243                                 ca_file,
 244                                 gnutls_strerror(rc),
 245                                 rc);
 246                         goto done;
 247                 }
 248                 DBG_INFO("Loaded %d additional CAs", rc);
 249         }
 250
 251         /*
 252          * Drivers often exist for quite some time, so it is possible that one
 253          * of the certificates in the trust list expired.
 254          * This is not a big deal, but we need to disable the time checks
 255          * or the verification will fail.
 256          */
 257         flags = GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS|
 258                 GNUTLS_VERIFY_DISABLE_TIME_CHECKS;
 259
 260 #if GNUTLS_VERSION_NUMBER >= 0x030600
 261         /* The "Microsoft Root Authority" certificate uses SHA1 */
 262         flags |= GNUTLS_VERIFY_ALLOW_SIGN_WITH_SHA1;
 263 #endif
 264
 265         count = gnutls_pkcs7_get_signature_count(mp7->c);
 266         if (count == 0) {
 267                 DBG_ERR("Failed to verify catalog file, no signatures found");
 268                 goto done;
 269         }
 270
 271         for (i = 0; i < count; i++) {
 272                 rc = gnutls_pkcs7_verify(mp7->c,
 273                                          tl,
 274                                          NULL, /* vdata */
 275                                          0,    /* vdata_size */
 276                                          i,    /* index */
 277                                          NULL, /* data */
 278                                          flags);   /* flags */
 279                 if (rc < 0) {
 280                         DBG_ERR("Failed to verify catalog file - %s (%d)",
 281                                 gnutls_strerror(rc),
 282                                 rc);
 283                         goto done;
 284                 }
 285         }
 286
 287         rc = 0;
 288 done:
 289         gnutls_x509_trust_list_deinit(tl, 1);
 290         talloc_free(tmp_ctx);
 291         return rc;
 292 }