1 /* Crypto operations using stored keys 2 * 3 * Copyright (c) 2016, Intel Corporation 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 */ 10 11 #include <linux/slab.h> 12 #include <linux/uaccess.h> 13 #include <linux/scatterlist.h> 14 #include <linux/crypto.h> 15 #include <crypto/hash.h> 16 #include <crypto/kpp.h> 17 #include <crypto/dh.h> 18 #include <keys/user-type.h> 19 #include "internal.h" 20 21 static ssize_t dh_data_from_key(key_serial_t keyid, void **data) 22 { 23 struct key *key; 24 key_ref_t key_ref; 25 long status; 26 ssize_t ret; 27 28 key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ); 29 if (IS_ERR(key_ref)) { 30 ret = -ENOKEY; 31 goto error; 32 } 33 34 key = key_ref_to_ptr(key_ref); 35 36 ret = -EOPNOTSUPP; 37 if (key->type == &key_type_user) { 38 down_read(&key->sem); 39 status = key_validate(key); 40 if (status == 0) { 41 const struct user_key_payload *payload; 42 uint8_t *duplicate; 43 44 payload = user_key_payload_locked(key); 45 46 duplicate = kmemdup(payload->data, payload->datalen, 47 GFP_KERNEL); 48 if (duplicate) { 49 *data = duplicate; 50 ret = payload->datalen; 51 } else { 52 ret = -ENOMEM; 53 } 54 } 55 up_read(&key->sem); 56 } 57 58 key_put(key); 59 error: 60 return ret; 61 } 62 63 static void dh_free_data(struct dh *dh) 64 { 65 kzfree(dh->key); 66 kzfree(dh->p); 67 kzfree(dh->g); 68 } 69 70 struct dh_completion { 71 struct completion completion; 72 int err; 73 }; 74 75 static void dh_crypto_done(struct crypto_async_request *req, int err) 76 { 77 struct dh_completion *compl = req->data; 78 79 if (err == -EINPROGRESS) 80 return; 81 82 compl->err = err; 83 complete(&compl->completion); 84 } 85 86 struct kdf_sdesc { 87 struct shash_desc shash; 88 char ctx[]; 89 }; 90 91 static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname) 92 { 93 struct crypto_shash *tfm; 94 struct kdf_sdesc *sdesc; 95 int size; 96 int err; 97 98 /* allocate synchronous hash */ 99 tfm = crypto_alloc_shash(hashname, 0, 0); 100 if (IS_ERR(tfm)) { 101 pr_info("could not allocate digest TFM handle %s\n", hashname); 102 return PTR_ERR(tfm); 103 } 104 105 err = -EINVAL; 106 if (crypto_shash_digestsize(tfm) == 0) 107 goto out_free_tfm; 108 109 err = -ENOMEM; 110 size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm); 111 sdesc = kmalloc(size, GFP_KERNEL); 112 if (!sdesc) 113 goto out_free_tfm; 114 sdesc->shash.tfm = tfm; 115 sdesc->shash.flags = 0x0; 116 117 *sdesc_ret = sdesc; 118 119 return 0; 120 121 out_free_tfm: 122 crypto_free_shash(tfm); 123 return err; 124 } 125 126 static void kdf_dealloc(struct kdf_sdesc *sdesc) 127 { 128 if (!sdesc) 129 return; 130 131 if (sdesc->shash.tfm) 132 crypto_free_shash(sdesc->shash.tfm); 133 134 kzfree(sdesc); 135 } 136 137 /* 138 * Implementation of the KDF in counter mode according to SP800-108 section 5.1 139 * as well as SP800-56A section 5.8.1 (Single-step KDF). 140 * 141 * SP800-56A: 142 * The src pointer is defined as Z || other info where Z is the shared secret 143 * from DH and other info is an arbitrary string (see SP800-56A section 144 * 5.8.1.2). 145 * 146 * 'dlen' must be a multiple of the digest size. 147 */ 148 static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, 149 u8 *dst, unsigned int dlen, unsigned int zlen) 150 { 151 struct shash_desc *desc = &sdesc->shash; 152 unsigned int h = crypto_shash_digestsize(desc->tfm); 153 int err = 0; 154 u8 *dst_orig = dst; 155 __be32 counter = cpu_to_be32(1); 156 157 while (dlen) { 158 err = crypto_shash_init(desc); 159 if (err) 160 goto err; 161 162 err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32)); 163 if (err) 164 goto err; 165 166 if (zlen && h) { 167 u8 tmpbuffer[32]; 168 size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer)); 169 memset(tmpbuffer, 0, chunk); 170 171 do { 172 err = crypto_shash_update(desc, tmpbuffer, 173 chunk); 174 if (err) 175 goto err; 176 177 zlen -= chunk; 178 chunk = min_t(size_t, zlen, sizeof(tmpbuffer)); 179 } while (zlen); 180 } 181 182 if (src && slen) { 183 err = crypto_shash_update(desc, src, slen); 184 if (err) 185 goto err; 186 } 187 188 err = crypto_shash_final(desc, dst); 189 if (err) 190 goto err; 191 192 dlen -= h; 193 dst += h; 194 counter = cpu_to_be32(be32_to_cpu(counter) + 1); 195 } 196 197 return 0; 198 199 err: 200 memzero_explicit(dst_orig, dlen); 201 return err; 202 } 203 204 static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc, 205 char __user *buffer, size_t buflen, 206 uint8_t *kbuf, size_t kbuflen, size_t lzero) 207 { 208 uint8_t *outbuf = NULL; 209 int ret; 210 size_t outbuf_len = roundup(buflen, 211 crypto_shash_digestsize(sdesc->shash.tfm)); 212 213 outbuf = kmalloc(outbuf_len, GFP_KERNEL); 214 if (!outbuf) { 215 ret = -ENOMEM; 216 goto err; 217 } 218 219 ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero); 220 if (ret) 221 goto err; 222 223 ret = buflen; 224 if (copy_to_user(buffer, outbuf, buflen) != 0) 225 ret = -EFAULT; 226 227 err: 228 kzfree(outbuf); 229 return ret; 230 } 231 232 long __keyctl_dh_compute(struct keyctl_dh_params __user *params, 233 char __user *buffer, size_t buflen, 234 struct keyctl_kdf_params *kdfcopy) 235 { 236 long ret; 237 ssize_t dlen; 238 int secretlen; 239 int outlen; 240 struct keyctl_dh_params pcopy; 241 struct dh dh_inputs; 242 struct scatterlist outsg; 243 struct dh_completion compl; 244 struct crypto_kpp *tfm; 245 struct kpp_request *req; 246 uint8_t *secret; 247 uint8_t *outbuf; 248 struct kdf_sdesc *sdesc = NULL; 249 250 if (!params || (!buffer && buflen)) { 251 ret = -EINVAL; 252 goto out1; 253 } 254 if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) { 255 ret = -EFAULT; 256 goto out1; 257 } 258 259 if (kdfcopy) { 260 char *hashname; 261 262 if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) { 263 ret = -EINVAL; 264 goto out1; 265 } 266 267 if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN || 268 kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) { 269 ret = -EMSGSIZE; 270 goto out1; 271 } 272 273 /* get KDF name string */ 274 hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME); 275 if (IS_ERR(hashname)) { 276 ret = PTR_ERR(hashname); 277 goto out1; 278 } 279 280 /* allocate KDF from the kernel crypto API */ 281 ret = kdf_alloc(&sdesc, hashname); 282 kfree(hashname); 283 if (ret) 284 goto out1; 285 } 286 287 memset(&dh_inputs, 0, sizeof(dh_inputs)); 288 289 dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p); 290 if (dlen < 0) { 291 ret = dlen; 292 goto out1; 293 } 294 dh_inputs.p_size = dlen; 295 296 dlen = dh_data_from_key(pcopy.base, &dh_inputs.g); 297 if (dlen < 0) { 298 ret = dlen; 299 goto out2; 300 } 301 dh_inputs.g_size = dlen; 302 303 dlen = dh_data_from_key(pcopy.private, &dh_inputs.key); 304 if (dlen < 0) { 305 ret = dlen; 306 goto out2; 307 } 308 dh_inputs.key_size = dlen; 309 310 secretlen = crypto_dh_key_len(&dh_inputs); 311 secret = kmalloc(secretlen, GFP_KERNEL); 312 if (!secret) { 313 ret = -ENOMEM; 314 goto out2; 315 } 316 ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs); 317 if (ret) 318 goto out3; 319 320 tfm = crypto_alloc_kpp("dh", 0, 0); 321 if (IS_ERR(tfm)) { 322 ret = PTR_ERR(tfm); 323 goto out3; 324 } 325 326 ret = crypto_kpp_set_secret(tfm, secret, secretlen); 327 if (ret) 328 goto out4; 329 330 outlen = crypto_kpp_maxsize(tfm); 331 332 if (!kdfcopy) { 333 /* 334 * When not using a KDF, buflen 0 is used to read the 335 * required buffer length 336 */ 337 if (buflen == 0) { 338 ret = outlen; 339 goto out4; 340 } else if (outlen > buflen) { 341 ret = -EOVERFLOW; 342 goto out4; 343 } 344 } 345 346 outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen, 347 GFP_KERNEL); 348 if (!outbuf) { 349 ret = -ENOMEM; 350 goto out4; 351 } 352 353 sg_init_one(&outsg, outbuf, outlen); 354 355 req = kpp_request_alloc(tfm, GFP_KERNEL); 356 if (!req) { 357 ret = -ENOMEM; 358 goto out5; 359 } 360 361 kpp_request_set_input(req, NULL, 0); 362 kpp_request_set_output(req, &outsg, outlen); 363 init_completion(&compl.completion); 364 kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | 365 CRYPTO_TFM_REQ_MAY_SLEEP, 366 dh_crypto_done, &compl); 367 368 /* 369 * For DH, generate_public_key and generate_shared_secret are 370 * the same calculation 371 */ 372 ret = crypto_kpp_generate_public_key(req); 373 if (ret == -EINPROGRESS) { 374 wait_for_completion(&compl.completion); 375 ret = compl.err; 376 if (ret) 377 goto out6; 378 } 379 380 if (kdfcopy) { 381 /* 382 * Concatenate SP800-56A otherinfo past DH shared secret -- the 383 * input to the KDF is (DH shared secret || otherinfo) 384 */ 385 if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo, 386 kdfcopy->otherinfolen) != 0) { 387 ret = -EFAULT; 388 goto out6; 389 } 390 391 ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf, 392 req->dst_len + kdfcopy->otherinfolen, 393 outlen - req->dst_len); 394 } else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) { 395 ret = req->dst_len; 396 } else { 397 ret = -EFAULT; 398 } 399 400 out6: 401 kpp_request_free(req); 402 out5: 403 kzfree(outbuf); 404 out4: 405 crypto_free_kpp(tfm); 406 out3: 407 kzfree(secret); 408 out2: 409 dh_free_data(&dh_inputs); 410 out1: 411 kdf_dealloc(sdesc); 412 return ret; 413 } 414 415 long keyctl_dh_compute(struct keyctl_dh_params __user *params, 416 char __user *buffer, size_t buflen, 417 struct keyctl_kdf_params __user *kdf) 418 { 419 struct keyctl_kdf_params kdfcopy; 420 421 if (!kdf) 422 return __keyctl_dh_compute(params, buffer, buflen, NULL); 423 424 if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0) 425 return -EFAULT; 426 427 return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy); 428 } 429