src/shared/cryptsetup-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "alloc-util.h"
   4 #include "cryptsetup-util.h"
   5 #include "dlfcn-util.h"
   6 #include "log.h"
   7 #include "parse-util.h"
   8
   9 #if HAVE_LIBCRYPTSETUP
  10 static void *cryptsetup_dl = NULL;
  11
  12 DLSYM_FUNCTION(crypt_activate_by_passphrase);
  13 #if HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
  14 DLSYM_FUNCTION(crypt_activate_by_signed_key);
  15 #endif
  16 DLSYM_FUNCTION(crypt_activate_by_volume_key);
  17 DLSYM_FUNCTION(crypt_deactivate_by_name);
  18 DLSYM_FUNCTION(crypt_format);
  19 DLSYM_FUNCTION(crypt_free);
  20 DLSYM_FUNCTION(crypt_get_cipher);
  21 DLSYM_FUNCTION(crypt_get_cipher_mode);
  22 DLSYM_FUNCTION(crypt_get_data_offset);
  23 DLSYM_FUNCTION(crypt_get_device_name);
  24 DLSYM_FUNCTION(crypt_get_dir);
  25 DLSYM_FUNCTION(crypt_get_type);
  26 DLSYM_FUNCTION(crypt_get_uuid);
  27 DLSYM_FUNCTION(crypt_get_verity_info);
  28 DLSYM_FUNCTION(crypt_get_volume_key_size);
  29 DLSYM_FUNCTION(crypt_init);
  30 DLSYM_FUNCTION(crypt_init_by_name);
  31 DLSYM_FUNCTION(crypt_keyslot_add_by_volume_key);
  32 DLSYM_FUNCTION(crypt_keyslot_destroy);
  33 DLSYM_FUNCTION(crypt_keyslot_max);
  34 DLSYM_FUNCTION(crypt_load);
  35 DLSYM_FUNCTION(crypt_resize);
  36 #if HAVE_CRYPT_RESUME_BY_VOLUME_KEY
  37 DLSYM_FUNCTION(crypt_resume_by_volume_key);
  38 #endif
  39 DLSYM_FUNCTION(crypt_set_data_device);
  40 DLSYM_FUNCTION(crypt_set_debug_level);
  41 DLSYM_FUNCTION(crypt_set_log_callback);
  42 #if HAVE_CRYPT_SET_METADATA_SIZE
  43 DLSYM_FUNCTION(crypt_set_metadata_size);
  44 #endif
  45 DLSYM_FUNCTION(crypt_set_pbkdf_type);
  46 DLSYM_FUNCTION(crypt_suspend);
  47 DLSYM_FUNCTION(crypt_token_json_get);
  48 DLSYM_FUNCTION(crypt_token_json_set);
  49 #if HAVE_CRYPT_TOKEN_MAX
  50 DLSYM_FUNCTION(crypt_token_max);
  51 #endif
  52 DLSYM_FUNCTION(crypt_token_status);
  53 DLSYM_FUNCTION(crypt_volume_key_get);
  54 #if HAVE_CRYPT_REENCRYPT_INIT_BY_PASSPHRASE
  55 DLSYM_FUNCTION(crypt_reencrypt_init_by_passphrase);
  56 #endif
  57 #if HAVE_CRYPT_REENCRYPT
  58 DISABLE_WARNING_DEPRECATED_DECLARATIONS;
  59 DLSYM_FUNCTION(crypt_reencrypt);
  60 REENABLE_WARNING;
  61 #endif
  62 DLSYM_FUNCTION(crypt_metadata_locking);
  63 #if HAVE_CRYPT_SET_DATA_OFFSET
  64 DLSYM_FUNCTION(crypt_set_data_offset);
  65 #endif
  66 DLSYM_FUNCTION(crypt_header_restore);
  67 DLSYM_FUNCTION(crypt_volume_key_keyring);
  68
  69 /* Unfortunately libcryptsetup provides neither an environment variable to redirect where to look for token
  70  * modules, nor does it have an API to change the token lookup path at runtime. The maintainers suggest using
  71  * ELF interposition instead (see https://gitlab.com/cryptsetup/cryptsetup/-/issues/846). Hence let's do
  72  * that: let's interpose libcryptsetup's crypt_token_external_path() function with our own, that *does*
  73  * honour an environment variable where to look for tokens. This is tremendously useful for debugging
  74  * libcryptsetup tokens: set the environment variable to your build dir and you can easily test token modules
  75  * without jumping through various hoops. */
  76
  77 /* Do this only on new enough compilers that actually support the "symver" attribute. Given this is a debug
  78  * feature, let's simply not bother on older compilers */
  79 #if BUILD_MODE_DEVELOPER && defined(__has_attribute) && __has_attribute(symver)
  80 const char *my_crypt_token_external_path(void); /* prototype for our own implementation */
  81
  82 /* We use the "symver" attribute to mark this implementation as the default implementation, and drop the
  83  * SD_SHARED namespace we by default attach to our symbols via a version script. */
  84 __attribute__((symver("crypt_token_external_path@@")))
  85 _public_ const char *my_crypt_token_external_path(void) {
  86         const char *e;
  87
  88         e = secure_getenv("SYSTEMD_CRYPTSETUP_TOKEN_PATH");
  89         if (e)
  90                 return e;
  91
  92         /* Now chain invoke the original implementation. */
  93         if (cryptsetup_dl) {
  94                 typeof(crypt_token_external_path) *func;
  95                 func = (typeof(crypt_token_external_path)*) dlsym(cryptsetup_dl, "crypt_token_external_path");
  96                 if (func)
  97                         return func();
  98         }
  99
 100         return NULL;
 101 }
 102 #endif
 103
 104 static void cryptsetup_log_glue(int level, const char *msg, void *usrptr) {
 105
 106         switch (level) {
 107         case CRYPT_LOG_NORMAL:
 108                 level = LOG_NOTICE;
 109                 break;
 110         case CRYPT_LOG_ERROR:
 111                 level = LOG_ERR;
 112                 break;
 113         case CRYPT_LOG_VERBOSE:
 114                 level = LOG_INFO;
 115                 break;
 116         case CRYPT_LOG_DEBUG:
 117                 level = LOG_DEBUG;
 118                 break;
 119         default:
 120                 log_error("Unknown libcryptsetup log level: %d", level);
 121                 level = LOG_ERR;
 122         }
 123
 124         log_full(level, "%s", msg);
 125 }
 126
 127 void cryptsetup_enable_logging(struct crypt_device *cd) {
 128         /* It's OK to call this with a NULL parameter, in which case libcryptsetup will set the default log
 129          * function.
 130          *
 131          * Note that this is also called from dlopen_cryptsetup(), which we call here too. Sounds like an
 132          * endless loop, but isn't because we break it via the check for 'cryptsetup_dl' early in
 133          * dlopen_cryptsetup(). */
 134
 135         if (dlopen_cryptsetup() < 0)
 136                 return; /* If this fails, let's gracefully ignore the issue, this is just debug logging after
 137                          * all, and if this failed we already generated a debug log message that should help
 138                          * to track things down. */
 139
 140         sym_crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
 141         sym_crypt_set_debug_level(DEBUG_LOGGING ? CRYPT_DEBUG_ALL : CRYPT_DEBUG_NONE);
 142 }
 143
 144 int cryptsetup_set_minimal_pbkdf(struct crypt_device *cd) {
 145
 146         /* With CRYPT_PBKDF_NO_BENCHMARK flag set .time_ms member is ignored
 147          * while .iterations must be set at least to recommended minimum value. */
 148
 149         static const struct crypt_pbkdf_type minimal_pbkdf = {
 150                 .hash = "sha512",
 151                 .type = CRYPT_KDF_PBKDF2,
 152                 .iterations = 1000, /* recommended minimum count for pbkdf2
 153                                      * according to NIST SP 800-132, ch. 5.2 */
 154                 .flags = CRYPT_PBKDF_NO_BENCHMARK
 155         };
 156
 157         int r;
 158
 159         /* Sets a minimal PKBDF in case we already have a high entropy key. */
 160
 161         r = dlopen_cryptsetup();
 162         if (r < 0)
 163                 return r;
 164
 165         r = sym_crypt_set_pbkdf_type(cd, &minimal_pbkdf);
 166         if (r < 0)
 167                 return r;
 168
 169         return 0;
 170 }
 171
 172 int cryptsetup_get_token_as_json(
 173                 struct crypt_device *cd,
 174                 int idx,
 175                 const char *verify_type,
 176                 JsonVariant **ret) {
 177
 178         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
 179         const char *text;
 180         int r;
 181
 182         assert(cd);
 183
 184         /* Extracts and parses the LUKS2 JSON token data from a LUKS2 device. Optionally verifies the type of
 185          * the token. Returns:
 186          *
 187          *      -EINVAL → token index out of range or "type" field missing
 188          *      -ENOENT → token doesn't exist
 189          * -EMEDIUMTYPE → "verify_type" specified and doesn't match token's type
 190          */
 191
 192         r = dlopen_cryptsetup();
 193         if (r < 0)
 194                 return r;
 195
 196         r = sym_crypt_token_json_get(cd, idx, &text);
 197         if (r < 0)
 198                 return r;
 199
 200         r = json_parse(text, 0, &v, NULL, NULL);
 201         if (r < 0)
 202                 return r;
 203
 204         if (verify_type) {
 205                 JsonVariant *w;
 206
 207                 w = json_variant_by_key(v, "type");
 208                 if (!w)
 209                         return -EINVAL;
 210
 211                 if (!streq_ptr(json_variant_string(w), verify_type))
 212                         return -EMEDIUMTYPE;
 213         }
 214
 215         if (ret)
 216                 *ret = TAKE_PTR(v);
 217
 218         return 0;
 219 }
 220
 221 int cryptsetup_add_token_json(struct crypt_device *cd, JsonVariant *v) {
 222         _cleanup_free_ char *text = NULL;
 223         int r;
 224
 225         r = dlopen_cryptsetup();
 226         if (r < 0)
 227                 return r;
 228
 229         r = json_variant_format(v, 0, &text);
 230         if (r < 0)
 231                 return log_debug_errno(r, "Failed to format token data for LUKS: %m");
 232
 233         log_debug("Adding token text <%s>", text);
 234
 235         r = sym_crypt_token_json_set(cd, CRYPT_ANY_TOKEN, text);
 236         if (r < 0)
 237                 return log_debug_errno(r, "Failed to write token data to LUKS: %m");
 238
 239         return 0;
 240 }
 241 #endif
 242
 243 int dlopen_cryptsetup(void) {
 244 #if HAVE_LIBCRYPTSETUP
 245         int r;
 246
 247         /* libcryptsetup added crypt_reencrypt() in 2.2.0, and marked it obsolete in 2.4.0, replacing it with
 248          * crypt_reencrypt_run(), which takes one extra argument but is otherwise identical. The old call is
 249          * still available though, and given we want to support 2.2.0 for a while longer, we'll stick to the
 250          * old symbol. However, the old symbols now has a GCC deprecation decorator, hence let's turn off
 251          * warnings about this for now. */
 252
 253         DISABLE_WARNING_DEPRECATED_DECLARATIONS;
 254
 255         ELF_NOTE_DLOPEN("cryptsetup",
 256                         "Support for disk encryption, integrity, and authentication",
 257                         ELF_NOTE_DLOPEN_PRIORITY_SUGGESTED,
 258                         "libcryptsetup.so.12");
 259
 260         r = dlopen_many_sym_or_warn(
 261                         &cryptsetup_dl, "libcryptsetup.so.12", LOG_DEBUG,
 262                         DLSYM_ARG(crypt_activate_by_passphrase),
 263 #if HAVE_CRYPT_ACTIVATE_BY_SIGNED_KEY
 264                         DLSYM_ARG(crypt_activate_by_signed_key),
 265 #endif
 266                         DLSYM_ARG(crypt_activate_by_volume_key),
 267                         DLSYM_ARG(crypt_deactivate_by_name),
 268                         DLSYM_ARG(crypt_format),
 269                         DLSYM_ARG(crypt_free),
 270                         DLSYM_ARG(crypt_get_cipher),
 271                         DLSYM_ARG(crypt_get_cipher_mode),
 272                         DLSYM_ARG(crypt_get_data_offset),
 273                         DLSYM_ARG(crypt_get_device_name),
 274                         DLSYM_ARG(crypt_get_dir),
 275                         DLSYM_ARG(crypt_get_type),
 276                         DLSYM_ARG(crypt_get_uuid),
 277                         DLSYM_ARG(crypt_get_verity_info),
 278                         DLSYM_ARG(crypt_get_volume_key_size),
 279                         DLSYM_ARG(crypt_init),
 280                         DLSYM_ARG(crypt_init_by_name),
 281                         DLSYM_ARG(crypt_keyslot_add_by_volume_key),
 282                         DLSYM_ARG(crypt_keyslot_destroy),
 283                         DLSYM_ARG(crypt_keyslot_max),
 284                         DLSYM_ARG(crypt_load),
 285                         DLSYM_ARG(crypt_resize),
 286 #if HAVE_CRYPT_RESUME_BY_VOLUME_KEY
 287                         DLSYM_ARG(crypt_resume_by_volume_key),
 288 #endif
 289                         DLSYM_ARG(crypt_set_data_device),
 290                         DLSYM_ARG(crypt_set_debug_level),
 291                         DLSYM_ARG(crypt_set_log_callback),
 292 #if HAVE_CRYPT_SET_METADATA_SIZE
 293                         DLSYM_ARG(crypt_set_metadata_size),
 294 #endif
 295                         DLSYM_ARG(crypt_set_pbkdf_type),
 296                         DLSYM_ARG(crypt_suspend),
 297                         DLSYM_ARG(crypt_token_json_get),
 298                         DLSYM_ARG(crypt_token_json_set),
 299 #if HAVE_CRYPT_TOKEN_MAX
 300                         DLSYM_ARG(crypt_token_max),
 301 #endif
 302                         DLSYM_ARG(crypt_token_status),
 303                         DLSYM_ARG(crypt_volume_key_get),
 304 #if HAVE_CRYPT_REENCRYPT_INIT_BY_PASSPHRASE
 305                         DLSYM_ARG(crypt_reencrypt_init_by_passphrase),
 306 #endif
 307 #if HAVE_CRYPT_REENCRYPT
 308                         DLSYM_ARG(crypt_reencrypt),
 309 #endif
 310                         DLSYM_ARG(crypt_metadata_locking),
 311 #if HAVE_CRYPT_SET_DATA_OFFSET
 312                         DLSYM_ARG(crypt_set_data_offset),
 313 #endif
 314                         DLSYM_ARG(crypt_header_restore),
 315                         DLSYM_ARG(crypt_volume_key_keyring));
 316         if (r <= 0)
 317                 return r;
 318
 319         REENABLE_WARNING;
 320
 321         /* Redirect the default logging calls of libcryptsetup to our own logging infra. (Note that
 322          * libcryptsetup also maintains per-"struct crypt_device" log functions, which we'll also set
 323          * whenever allocating a "struct crypt_device" context. Why set both? To be defensive: maybe some
 324          * other code loaded into this process also changes the global log functions of libcryptsetup, who
 325          * knows? And if so, we still want our own objects to log via our own infra, at the very least.) */
 326         cryptsetup_enable_logging(NULL);
 327         return 1;
 328 #else
 329         return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "cryptsetup support is not compiled in.");
 330 #endif
 331 }
 332
 333 int cryptsetup_get_keyslot_from_token(JsonVariant *v) {
 334         int keyslot, r;
 335         JsonVariant *w;
 336
 337         /* Parses the "keyslots" field of a LUKS2 token object. The field can be an array, but here we assume
 338          * that it contains a single element only, since that's the only way we ever generate it
 339          * ourselves. */
 340
 341         w = json_variant_by_key(v, "keyslots");
 342         if (!w)
 343                 return -ENOENT;
 344         if (!json_variant_is_array(w) || json_variant_elements(w) != 1)
 345                 return -EMEDIUMTYPE;
 346
 347         w = json_variant_by_index(w, 0);
 348         if (!w)
 349                 return -ENOENT;
 350         if (!json_variant_is_string(w))
 351                 return -EMEDIUMTYPE;
 352
 353         r = safe_atoi(json_variant_string(w), &keyslot);
 354         if (r < 0)
 355                 return r;
 356         if (keyslot < 0)
 357                 return -EINVAL;
 358
 359         return keyslot;
 360 }