drivers/nvme/common/auth.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2020 Hannes Reinecke, SUSE Linux
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/crc32.h>
   8 #include <linux/base64.h>
   9 #include <linux/prandom.h>
  10 #include <linux/scatterlist.h>
  11 #include <asm/unaligned.h>
  12 #include <crypto/hash.h>
  13 #include <crypto/dh.h>
  14 #include <linux/nvme.h>
  15 #include <linux/nvme-auth.h>
  16
  17 static u32 nvme_dhchap_seqnum;
  18 static DEFINE_MUTEX(nvme_dhchap_mutex);
  19
  20 u32 nvme_auth_get_seqnum(void)
  21 {
  22         u32 seqnum;
  23
  24         mutex_lock(&nvme_dhchap_mutex);
  25         if (!nvme_dhchap_seqnum)
  26                 nvme_dhchap_seqnum = get_random_u32();
  27         else {
  28                 nvme_dhchap_seqnum++;
  29                 if (!nvme_dhchap_seqnum)
  30                         nvme_dhchap_seqnum++;
  31         }
  32         seqnum = nvme_dhchap_seqnum;
  33         mutex_unlock(&nvme_dhchap_mutex);
  34         return seqnum;
  35 }
  36 EXPORT_SYMBOL_GPL(nvme_auth_get_seqnum);
  37
  38 static struct nvme_auth_dhgroup_map {
  39         const char name[16];
  40         const char kpp[16];
  41 } dhgroup_map[] = {
  42         [NVME_AUTH_DHGROUP_NULL] = {
  43                 .name = "null", .kpp = "null" },
  44         [NVME_AUTH_DHGROUP_2048] = {
  45                 .name = "ffdhe2048", .kpp = "ffdhe2048(dh)" },
  46         [NVME_AUTH_DHGROUP_3072] = {
  47                 .name = "ffdhe3072", .kpp = "ffdhe3072(dh)" },
  48         [NVME_AUTH_DHGROUP_4096] = {
  49                 .name = "ffdhe4096", .kpp = "ffdhe4096(dh)" },
  50         [NVME_AUTH_DHGROUP_6144] = {
  51                 .name = "ffdhe6144", .kpp = "ffdhe6144(dh)" },
  52         [NVME_AUTH_DHGROUP_8192] = {
  53                 .name = "ffdhe8192", .kpp = "ffdhe8192(dh)" },
  54 };
  55
  56 const char *nvme_auth_dhgroup_name(u8 dhgroup_id)
  57 {
  58         if (dhgroup_id >= ARRAY_SIZE(dhgroup_map))
  59                 return NULL;
  60         return dhgroup_map[dhgroup_id].name;
  61 }
  62 EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_name);
  63
  64 const char *nvme_auth_dhgroup_kpp(u8 dhgroup_id)
  65 {
  66         if (dhgroup_id >= ARRAY_SIZE(dhgroup_map))
  67                 return NULL;
  68         return dhgroup_map[dhgroup_id].kpp;
  69 }
  70 EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_kpp);
  71
  72 u8 nvme_auth_dhgroup_id(const char *dhgroup_name)
  73 {
  74         int i;
  75
  76         if (!dhgroup_name || !strlen(dhgroup_name))
  77                 return NVME_AUTH_DHGROUP_INVALID;
  78         for (i = 0; i < ARRAY_SIZE(dhgroup_map); i++) {
  79                 if (!strlen(dhgroup_map[i].name))
  80                         continue;
  81                 if (!strncmp(dhgroup_map[i].name, dhgroup_name,
  82                              strlen(dhgroup_map[i].name)))
  83                         return i;
  84         }
  85         return NVME_AUTH_DHGROUP_INVALID;
  86 }
  87 EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_id);
  88
  89 static struct nvme_dhchap_hash_map {
  90         int len;
  91         const char hmac[15];
  92         const char digest[8];
  93 } hash_map[] = {
  94         [NVME_AUTH_HASH_SHA256] = {
  95                 .len = 32,
  96                 .hmac = "hmac(sha256)",
  97                 .digest = "sha256",
  98         },
  99         [NVME_AUTH_HASH_SHA384] = {
 100                 .len = 48,
 101                 .hmac = "hmac(sha384)",
 102                 .digest = "sha384",
 103         },
 104         [NVME_AUTH_HASH_SHA512] = {
 105                 .len = 64,
 106                 .hmac = "hmac(sha512)",
 107                 .digest = "sha512",
 108         },
 109 };
 110
 111 const char *nvme_auth_hmac_name(u8 hmac_id)
 112 {
 113         if (hmac_id >= ARRAY_SIZE(hash_map))
 114                 return NULL;
 115         return hash_map[hmac_id].hmac;
 116 }
 117 EXPORT_SYMBOL_GPL(nvme_auth_hmac_name);
 118
 119 const char *nvme_auth_digest_name(u8 hmac_id)
 120 {
 121         if (hmac_id >= ARRAY_SIZE(hash_map))
 122                 return NULL;
 123         return hash_map[hmac_id].digest;
 124 }
 125 EXPORT_SYMBOL_GPL(nvme_auth_digest_name);
 126
 127 u8 nvme_auth_hmac_id(const char *hmac_name)
 128 {
 129         int i;
 130
 131         if (!hmac_name || !strlen(hmac_name))
 132                 return NVME_AUTH_HASH_INVALID;
 133
 134         for (i = 0; i < ARRAY_SIZE(hash_map); i++) {
 135                 if (!strlen(hash_map[i].hmac))
 136                         continue;
 137                 if (!strncmp(hash_map[i].hmac, hmac_name,
 138                              strlen(hash_map[i].hmac)))
 139                         return i;
 140         }
 141         return NVME_AUTH_HASH_INVALID;
 142 }
 143 EXPORT_SYMBOL_GPL(nvme_auth_hmac_id);
 144
 145 size_t nvme_auth_hmac_hash_len(u8 hmac_id)
 146 {
 147         if (hmac_id >= ARRAY_SIZE(hash_map))
 148                 return 0;
 149         return hash_map[hmac_id].len;
 150 }
 151 EXPORT_SYMBOL_GPL(nvme_auth_hmac_hash_len);
 152
 153 u32 nvme_auth_key_struct_size(u32 key_len)
 154 {
 155         struct nvme_dhchap_key key;
 156
 157         return struct_size(&key, key, key_len);
 158 }
 159 EXPORT_SYMBOL_GPL(nvme_auth_key_struct_size);
 160
 161 struct nvme_dhchap_key *nvme_auth_extract_key(unsigned char *secret,
 162                                               u8 key_hash)
 163 {
 164         struct nvme_dhchap_key *key;
 165         unsigned char *p;
 166         u32 crc;
 167         int ret, key_len;
 168         size_t allocated_len = strlen(secret);
 169
 170         /* Secret might be affixed with a ':' */
 171         p = strrchr(secret, ':');
 172         if (p)
 173                 allocated_len = p - secret;
 174         key = nvme_auth_alloc_key(allocated_len, 0);
 175         if (!key)
 176                 return ERR_PTR(-ENOMEM);
 177
 178         key_len = base64_decode(secret, allocated_len, key->key);
 179         if (key_len < 0) {
 180                 pr_debug("base64 key decoding error %d\n",
 181                          key_len);
 182                 ret = key_len;
 183                 goto out_free_secret;
 184         }
 185
 186         if (key_len != 36 && key_len != 52 &&
 187             key_len != 68) {
 188                 pr_err("Invalid key len %d\n", key_len);
 189                 ret = -EINVAL;
 190                 goto out_free_secret;
 191         }
 192
 193         /* The last four bytes is the CRC in little-endian format */
 194         key_len -= 4;
 195         /*
 196          * The linux implementation doesn't do pre- and post-increments,
 197          * so we have to do it manually.
 198          */
 199         crc = ~crc32(~0, key->key, key_len);
 200
 201         if (get_unaligned_le32(key->key + key_len) != crc) {
 202                 pr_err("key crc mismatch (key %08x, crc %08x)\n",
 203                        get_unaligned_le32(key->key + key_len), crc);
 204                 ret = -EKEYREJECTED;
 205                 goto out_free_secret;
 206         }
 207         key->len = key_len;
 208         key->hash = key_hash;
 209         return key;
 210 out_free_secret:
 211         nvme_auth_free_key(key);
 212         return ERR_PTR(ret);
 213 }
 214 EXPORT_SYMBOL_GPL(nvme_auth_extract_key);
 215
 216 struct nvme_dhchap_key *nvme_auth_alloc_key(u32 len, u8 hash)
 217 {
 218         u32 num_bytes = nvme_auth_key_struct_size(len);
 219         struct nvme_dhchap_key *key = kzalloc(num_bytes, GFP_KERNEL);
 220
 221         if (key) {
 222                 key->len = len;
 223                 key->hash = hash;
 224         }
 225         return key;
 226 }
 227 EXPORT_SYMBOL_GPL(nvme_auth_alloc_key);
 228
 229 void nvme_auth_free_key(struct nvme_dhchap_key *key)
 230 {
 231         if (!key)
 232                 return;
 233         kfree_sensitive(key);
 234 }
 235 EXPORT_SYMBOL_GPL(nvme_auth_free_key);
 236
 237 struct nvme_dhchap_key *nvme_auth_transform_key(
 238                 struct nvme_dhchap_key *key, char *nqn)
 239 {
 240         const char *hmac_name;
 241         struct crypto_shash *key_tfm;
 242         struct shash_desc *shash;
 243         struct nvme_dhchap_key *transformed_key;
 244         int ret, key_len;
 245
 246         if (!key) {
 247                 pr_warn("No key specified\n");
 248                 return ERR_PTR(-ENOKEY);
 249         }
 250         if (key->hash == 0) {
 251                 key_len = nvme_auth_key_struct_size(key->len);
 252                 transformed_key = kmemdup(key, key_len, GFP_KERNEL);
 253                 if (!transformed_key)
 254                         return ERR_PTR(-ENOMEM);
 255                 return transformed_key;
 256         }
 257         hmac_name = nvme_auth_hmac_name(key->hash);
 258         if (!hmac_name) {
 259                 pr_warn("Invalid key hash id %d\n", key->hash);
 260                 return ERR_PTR(-EINVAL);
 261         }
 262
 263         key_tfm = crypto_alloc_shash(hmac_name, 0, 0);
 264         if (IS_ERR(key_tfm))
 265                 return ERR_CAST(key_tfm);
 266
 267         shash = kmalloc(sizeof(struct shash_desc) +
 268                         crypto_shash_descsize(key_tfm),
 269                         GFP_KERNEL);
 270         if (!shash) {
 271                 ret = -ENOMEM;
 272                 goto out_free_key;
 273         }
 274
 275         key_len = crypto_shash_digestsize(key_tfm);
 276         transformed_key = nvme_auth_alloc_key(key_len, key->hash);
 277         if (!transformed_key) {
 278                 ret = -ENOMEM;
 279                 goto out_free_shash;
 280         }
 281
 282         shash->tfm = key_tfm;
 283         ret = crypto_shash_setkey(key_tfm, key->key, key->len);
 284         if (ret < 0)
 285                 goto out_free_transformed_key;
 286         ret = crypto_shash_init(shash);
 287         if (ret < 0)
 288                 goto out_free_transformed_key;
 289         ret = crypto_shash_update(shash, nqn, strlen(nqn));
 290         if (ret < 0)
 291                 goto out_free_transformed_key;
 292         ret = crypto_shash_update(shash, "NVMe-over-Fabrics", 17);
 293         if (ret < 0)
 294                 goto out_free_transformed_key;
 295         ret = crypto_shash_final(shash, transformed_key->key);
 296         if (ret < 0)
 297                 goto out_free_transformed_key;
 298
 299         kfree(shash);
 300         crypto_free_shash(key_tfm);
 301
 302         return transformed_key;
 303
 304 out_free_transformed_key:
 305         nvme_auth_free_key(transformed_key);
 306 out_free_shash:
 307         kfree(shash);
 308 out_free_key:
 309         crypto_free_shash(key_tfm);
 310
 311         return ERR_PTR(ret);
 312 }
 313 EXPORT_SYMBOL_GPL(nvme_auth_transform_key);
 314
 315 static int nvme_auth_hash_skey(int hmac_id, u8 *skey, size_t skey_len, u8 *hkey)
 316 {
 317         const char *digest_name;
 318         struct crypto_shash *tfm;
 319         int ret;
 320
 321         digest_name = nvme_auth_digest_name(hmac_id);
 322         if (!digest_name) {
 323                 pr_debug("%s: failed to get digest for %d\n", __func__,
 324                          hmac_id);
 325                 return -EINVAL;
 326         }
 327         tfm = crypto_alloc_shash(digest_name, 0, 0);
 328         if (IS_ERR(tfm))
 329                 return -ENOMEM;
 330
 331         ret = crypto_shash_tfm_digest(tfm, skey, skey_len, hkey);
 332         if (ret < 0)
 333                 pr_debug("%s: Failed to hash digest len %zu\n", __func__,
 334                          skey_len);
 335
 336         crypto_free_shash(tfm);
 337         return ret;
 338 }
 339
 340 int nvme_auth_augmented_challenge(u8 hmac_id, u8 *skey, size_t skey_len,
 341                 u8 *challenge, u8 *aug, size_t hlen)
 342 {
 343         struct crypto_shash *tfm;
 344         u8 *hashed_key;
 345         const char *hmac_name;
 346         int ret;
 347
 348         hashed_key = kmalloc(hlen, GFP_KERNEL);
 349         if (!hashed_key)
 350                 return -ENOMEM;
 351
 352         ret = nvme_auth_hash_skey(hmac_id, skey,
 353                                   skey_len, hashed_key);
 354         if (ret < 0)
 355                 goto out_free_key;
 356
 357         hmac_name = nvme_auth_hmac_name(hmac_id);
 358         if (!hmac_name) {
 359                 pr_warn("%s: invalid hash algorithm %d\n",
 360                         __func__, hmac_id);
 361                 ret = -EINVAL;
 362                 goto out_free_key;
 363         }
 364
 365         tfm = crypto_alloc_shash(hmac_name, 0, 0);
 366         if (IS_ERR(tfm)) {
 367                 ret = PTR_ERR(tfm);
 368                 goto out_free_key;
 369         }
 370
 371         ret = crypto_shash_setkey(tfm, hashed_key, hlen);
 372         if (ret)
 373                 goto out_free_hash;
 374
 375         ret = crypto_shash_tfm_digest(tfm, challenge, hlen, aug);
 376 out_free_hash:
 377         crypto_free_shash(tfm);
 378 out_free_key:
 379         kfree_sensitive(hashed_key);
 380         return ret;
 381 }
 382 EXPORT_SYMBOL_GPL(nvme_auth_augmented_challenge);
 383
 384 int nvme_auth_gen_privkey(struct crypto_kpp *dh_tfm, u8 dh_gid)
 385 {
 386         int ret;
 387
 388         ret = crypto_kpp_set_secret(dh_tfm, NULL, 0);
 389         if (ret)
 390                 pr_debug("failed to set private key, error %d\n", ret);
 391
 392         return ret;
 393 }
 394 EXPORT_SYMBOL_GPL(nvme_auth_gen_privkey);
 395
 396 int nvme_auth_gen_pubkey(struct crypto_kpp *dh_tfm,
 397                 u8 *host_key, size_t host_key_len)
 398 {
 399         struct kpp_request *req;
 400         struct crypto_wait wait;
 401         struct scatterlist dst;
 402         int ret;
 403
 404         req = kpp_request_alloc(dh_tfm, GFP_KERNEL);
 405         if (!req)
 406                 return -ENOMEM;
 407
 408         crypto_init_wait(&wait);
 409         kpp_request_set_input(req, NULL, 0);
 410         sg_init_one(&dst, host_key, host_key_len);
 411         kpp_request_set_output(req, &dst, host_key_len);
 412         kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 413                                  crypto_req_done, &wait);
 414
 415         ret = crypto_wait_req(crypto_kpp_generate_public_key(req), &wait);
 416         kpp_request_free(req);
 417         return ret;
 418 }
 419 EXPORT_SYMBOL_GPL(nvme_auth_gen_pubkey);
 420
 421 int nvme_auth_gen_shared_secret(struct crypto_kpp *dh_tfm,
 422                 u8 *ctrl_key, size_t ctrl_key_len,
 423                 u8 *sess_key, size_t sess_key_len)
 424 {
 425         struct kpp_request *req;
 426         struct crypto_wait wait;
 427         struct scatterlist src, dst;
 428         int ret;
 429
 430         req = kpp_request_alloc(dh_tfm, GFP_KERNEL);
 431         if (!req)
 432                 return -ENOMEM;
 433
 434         crypto_init_wait(&wait);
 435         sg_init_one(&src, ctrl_key, ctrl_key_len);
 436         kpp_request_set_input(req, &src, ctrl_key_len);
 437         sg_init_one(&dst, sess_key, sess_key_len);
 438         kpp_request_set_output(req, &dst, sess_key_len);
 439         kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 440                                  crypto_req_done, &wait);
 441
 442         ret = crypto_wait_req(crypto_kpp_compute_shared_secret(req), &wait);
 443
 444         kpp_request_free(req);
 445         return ret;
 446 }
 447 EXPORT_SYMBOL_GPL(nvme_auth_gen_shared_secret);
 448
 449 int nvme_auth_generate_key(u8 *secret, struct nvme_dhchap_key **ret_key)
 450 {
 451         struct nvme_dhchap_key *key;
 452         u8 key_hash;
 453
 454         if (!secret) {
 455                 *ret_key = NULL;
 456                 return 0;
 457         }
 458
 459         if (sscanf(secret, "DHHC-1:%hhd:%*s:", &key_hash) != 1)
 460                 return -EINVAL;
 461
 462         /* Pass in the secret without the 'DHHC-1:XX:' prefix */
 463         key = nvme_auth_extract_key(secret + 10, key_hash);
 464         if (IS_ERR(key)) {
 465                 *ret_key = NULL;
 466                 return PTR_ERR(key);
 467         }
 468
 469         *ret_key = key;
 470         return 0;
 471 }
 472 EXPORT_SYMBOL_GPL(nvme_auth_generate_key);
 473
 474 MODULE_LICENSE("GPL v2");