1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * algif_aead: User-space interface for AEAD algorithms 4 * 5 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de> 6 * 7 * This file provides the user-space API for AEAD ciphers. 8 * 9 * The following concept of the memory management is used: 10 * 11 * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is 12 * filled by user space with the data submitted via sendmsg (maybe with 13 * MSG_SPLICE_PAGES). Filling up the TX SGL does not cause a crypto operation 14 * -- the data will only be tracked by the kernel. Upon receipt of one recvmsg 15 * call, the caller must provide a buffer which is tracked with the RX SGL. 16 * 17 * During the processing of the recvmsg operation, the cipher request is 18 * allocated and prepared. As part of the recvmsg operation, the processed 19 * TX buffers are extracted from the TX SGL into a separate SGL. 20 * 21 * After the completion of the crypto operation, the RX SGL and the cipher 22 * request is released. The extracted TX SGL parts are released together with 23 * the RX SGL release. 24 */ 25 26#include <crypto/internal/aead.h> 27#include <crypto/scatterwalk.h> 28#include <crypto/if_alg.h> 29#include <crypto/skcipher.h> 30#include <crypto/null.h> 31#include <linux/init.h> 32#include <linux/list.h> 33#include <linux/kernel.h> 34#include <linux/mm.h> 35#include <linux/module.h> 36#include <linux/net.h> 37#include <net/sock.h> 38 39struct aead_tfm { 40 struct crypto_aead *aead; 41 struct crypto_sync_skcipher *null_tfm; 42}; 43 44static inline bool aead_sufficient_data(struct sock *sk) 45{ 46 struct alg_sock *ask = alg_sk(sk); 47 struct sock *psk = ask->parent; 48 struct alg_sock *pask = alg_sk(psk); 49 struct af_alg_ctx *ctx = ask->private; 50 struct aead_tfm *aeadc = pask->private; 51 struct crypto_aead *tfm = aeadc->aead; 52 unsigned int as = crypto_aead_authsize(tfm); 53 54 /* 55 * The minimum amount of memory needed for an AEAD cipher is 56 * the AAD and in case of decryption the tag. 57 */ 58 return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as); 59} 60 61static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) 62{ 63 struct sock *sk = sock->sk; 64 struct alg_sock *ask = alg_sk(sk); 65 struct sock *psk = ask->parent; 66 struct alg_sock *pask = alg_sk(psk); 67 struct aead_tfm *aeadc = pask->private; 68 struct crypto_aead *tfm = aeadc->aead; 69 unsigned int ivsize = crypto_aead_ivsize(tfm); 70 71 return af_alg_sendmsg(sock, msg, size, ivsize); 72} 73 74static int crypto_aead_copy_sgl(struct crypto_sync_skcipher *null_tfm, 75 struct scatterlist *src, 76 struct scatterlist *dst, unsigned int len) 77{ 78 SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm); 79 80 skcipher_request_set_sync_tfm(skreq, null_tfm); 81 skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_SLEEP, 82 NULL, NULL); 83 skcipher_request_set_crypt(skreq, src, dst, len, NULL); 84 85 return crypto_skcipher_encrypt(skreq); 86} 87 88static int _aead_recvmsg(struct socket *sock, struct msghdr *msg, 89 size_t ignored, int flags) 90{ 91 struct sock *sk = sock->sk; 92 struct alg_sock *ask = alg_sk(sk); 93 struct sock *psk = ask->parent; 94 struct alg_sock *pask = alg_sk(psk); 95 struct af_alg_ctx *ctx = ask->private; 96 struct aead_tfm *aeadc = pask->private; 97 struct crypto_aead *tfm = aeadc->aead; 98 struct crypto_sync_skcipher *null_tfm = aeadc->null_tfm; 99 unsigned int i, as = crypto_aead_authsize(tfm); 100 struct af_alg_async_req *areq; 101 struct af_alg_tsgl *tsgl, *tmp; 102 struct scatterlist *rsgl_src, *tsgl_src = NULL; 103 int err = 0; 104 size_t used = 0; /* [in] TX bufs to be en/decrypted */ 105 size_t outlen = 0; /* [out] RX bufs produced by kernel */ 106 size_t usedpages = 0; /* [in] RX bufs to be used from user */ 107 size_t processed = 0; /* [in] TX bufs to be consumed */ 108 109 if (!ctx->init || ctx->more) { 110 err = af_alg_wait_for_data(sk, flags, 0); 111 if (err) 112 return err; 113 } 114 115 /* 116 * Data length provided by caller via sendmsg that has not yet been 117 * processed. 118 */ 119 used = ctx->used; 120 121 /* 122 * Make sure sufficient data is present -- note, the same check is also 123 * present in sendmsg. The checks in sendmsg shall provide an 124 * information to the data sender that something is wrong, but they are 125 * irrelevant to maintain the kernel integrity. We need this check 126 * here too in case user space decides to not honor the error message 127 * in sendmsg and still call recvmsg. This check here protects the 128 * kernel integrity. 129 */ 130 if (!aead_sufficient_data(sk)) 131 return -EINVAL; 132 133 /* 134 * Calculate the minimum output buffer size holding the result of the 135 * cipher operation. When encrypting data, the receiving buffer is 136 * larger by the tag length compared to the input buffer as the 137 * encryption operation generates the tag. For decryption, the input 138 * buffer provides the tag which is consumed resulting in only the 139 * plaintext without a buffer for the tag returned to the caller. 140 */ 141 if (ctx->enc) 142 outlen = used + as; 143 else 144 outlen = used - as; 145 146 /* 147 * The cipher operation input data is reduced by the associated data 148 * length as this data is processed separately later on. 149 */ 150 used -= ctx->aead_assoclen; 151 152 /* Allocate cipher request for current operation. */ 153 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + 154 crypto_aead_reqsize(tfm)); 155 if (IS_ERR(areq)) 156 return PTR_ERR(areq); 157 158 /* convert iovecs of output buffers into RX SGL */ 159 err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages); 160 if (err) 161 goto free; 162 163 /* 164 * Ensure output buffer is sufficiently large. If the caller provides 165 * less buffer space, only use the relative required input size. This 166 * allows AIO operation where the caller sent all data to be processed 167 * and the AIO operation performs the operation on the different chunks 168 * of the input data. 169 */ 170 if (usedpages < outlen) { 171 size_t less = outlen - usedpages; 172 173 if (used < less) { 174 err = -EINVAL; 175 goto free; 176 } 177 used -= less; 178 outlen -= less; 179 } 180 181 processed = used + ctx->aead_assoclen; 182 list_for_each_entry_safe(tsgl, tmp, &ctx->tsgl_list, list) { 183 for (i = 0; i < tsgl->cur; i++) { 184 struct scatterlist *process_sg = tsgl->sg + i; 185 186 if (!(process_sg->length) || !sg_page(process_sg)) 187 continue; 188 tsgl_src = process_sg; 189 break; 190 } 191 if (tsgl_src) 192 break; 193 } 194 if (processed && !tsgl_src) { 195 err = -EFAULT; 196 goto free; 197 } 198 199 /* 200 * Copy of AAD from source to destination 201 * 202 * The AAD is copied to the destination buffer without change. Even 203 * when user space uses an in-place cipher operation, the kernel 204 * will copy the data as it does not see whether such in-place operation 205 * is initiated. 206 * 207 * To ensure efficiency, the following implementation ensure that the 208 * ciphers are invoked to perform a crypto operation in-place. This 209 * is achieved by memory management specified as follows. 210 */ 211 212 /* Use the RX SGL as source (and destination) for crypto op. */ 213 rsgl_src = areq->first_rsgl.sgl.sgt.sgl; 214 215 if (ctx->enc) { 216 /* 217 * Encryption operation - The in-place cipher operation is 218 * achieved by the following operation: 219 * 220 * TX SGL: AAD || PT 221 * | | 222 * | copy | 223 * v v 224 * RX SGL: AAD || PT || Tag 225 */ 226 err = crypto_aead_copy_sgl(null_tfm, tsgl_src, 227 areq->first_rsgl.sgl.sgt.sgl, 228 processed); 229 if (err) 230 goto free; 231 af_alg_pull_tsgl(sk, processed, NULL, 0); 232 } else { 233 /* 234 * Decryption operation - To achieve an in-place cipher 235 * operation, the following SGL structure is used: 236 * 237 * TX SGL: AAD || CT || Tag 238 * | | ^ 239 * | copy | | Create SGL link. 240 * v v | 241 * RX SGL: AAD || CT ----+ 242 */ 243 244 /* Copy AAD || CT to RX SGL buffer for in-place operation. */ 245 err = crypto_aead_copy_sgl(null_tfm, tsgl_src, 246 areq->first_rsgl.sgl.sgt.sgl, 247 outlen); 248 if (err) 249 goto free; 250 251 /* Create TX SGL for tag and chain it to RX SGL. */ 252 areq->tsgl_entries = af_alg_count_tsgl(sk, processed, 253 processed - as); 254 if (!areq->tsgl_entries) 255 areq->tsgl_entries = 1; 256 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl), 257 areq->tsgl_entries), 258 GFP_KERNEL); 259 if (!areq->tsgl) { 260 err = -ENOMEM; 261 goto free; 262 } 263 sg_init_table(areq->tsgl, areq->tsgl_entries); 264 265 /* Release TX SGL, except for tag data and reassign tag data. */ 266 af_alg_pull_tsgl(sk, processed, areq->tsgl, processed - as); 267 268 /* chain the areq TX SGL holding the tag with RX SGL */ 269 if (usedpages) { 270 /* RX SGL present */ 271 struct af_alg_sgl *sgl_prev = &areq->last_rsgl->sgl; 272 struct scatterlist *sg = sgl_prev->sgt.sgl; 273 274 sg_unmark_end(sg + sgl_prev->sgt.nents - 1); 275 sg_chain(sg, sgl_prev->sgt.nents + 1, areq->tsgl); 276 } else 277 /* no RX SGL present (e.g. authentication only) */ 278 rsgl_src = areq->tsgl; 279 } 280 281 /* Initialize the crypto operation */ 282 aead_request_set_crypt(&areq->cra_u.aead_req, rsgl_src, 283 areq->first_rsgl.sgl.sgt.sgl, used, ctx->iv); 284 aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen); 285 aead_request_set_tfm(&areq->cra_u.aead_req, tfm); 286 287 if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { 288 /* AIO operation */ 289 sock_hold(sk); 290 areq->iocb = msg->msg_iocb; 291 292 /* Remember output size that will be generated. */ 293 areq->outlen = outlen; 294 295 aead_request_set_callback(&areq->cra_u.aead_req, 296 CRYPTO_TFM_REQ_MAY_SLEEP, 297 af_alg_async_cb, areq); 298 err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) : 299 crypto_aead_decrypt(&areq->cra_u.aead_req); 300 301 /* AIO operation in progress */ 302 if (err == -EINPROGRESS) 303 return -EIOCBQUEUED; 304 305 sock_put(sk); 306 } else { 307 /* Synchronous operation */ 308 aead_request_set_callback(&areq->cra_u.aead_req, 309 CRYPTO_TFM_REQ_MAY_SLEEP | 310 CRYPTO_TFM_REQ_MAY_BACKLOG, 311 crypto_req_done, &ctx->wait); 312 err = crypto_wait_req(ctx->enc ? 313 crypto_aead_encrypt(&areq->cra_u.aead_req) : 314 crypto_aead_decrypt(&areq->cra_u.aead_req), 315 &ctx->wait); 316 } 317 318 319free: 320 af_alg_free_resources(areq); 321 322 return err ? err : outlen; 323} 324 325static int aead_recvmsg(struct socket *sock, struct msghdr *msg, 326 size_t ignored, int flags) 327{ 328 struct sock *sk = sock->sk; 329 int ret = 0; 330 331 lock_sock(sk); 332 while (msg_data_left(msg)) { 333 int err = _aead_recvmsg(sock, msg, ignored, flags); 334 335 /* 336 * This error covers -EIOCBQUEUED which implies that we can 337 * only handle one AIO request. If the caller wants to have 338 * multiple AIO requests in parallel, he must make multiple 339 * separate AIO calls. 340 * 341 * Also return the error if no data has been processed so far. 342 */ 343 if (err <= 0) { 344 if (err == -EIOCBQUEUED || err == -EBADMSG || !ret) 345 ret = err; 346 goto out; 347 } 348 349 ret += err; 350 } 351 352out: 353 af_alg_wmem_wakeup(sk); 354 release_sock(sk); 355 return ret; 356} 357 358static struct proto_ops algif_aead_ops = { 359 .family = PF_ALG, 360 361 .connect = sock_no_connect, 362 .socketpair = sock_no_socketpair, 363 .getname = sock_no_getname, 364 .ioctl = sock_no_ioctl, 365 .listen = sock_no_listen, 366 .shutdown = sock_no_shutdown, 367 .mmap = sock_no_mmap, 368 .bind = sock_no_bind, 369 .accept = sock_no_accept, 370 371 .release = af_alg_release, 372 .sendmsg = aead_sendmsg, 373 .recvmsg = aead_recvmsg, 374 .poll = af_alg_poll, 375}; 376 377static int aead_check_key(struct socket *sock) 378{ 379 int err = 0; 380 struct sock *psk; 381 struct alg_sock *pask; 382 struct aead_tfm *tfm; 383 struct sock *sk = sock->sk; 384 struct alg_sock *ask = alg_sk(sk); 385 386 lock_sock(sk); 387 if (!atomic_read(&ask->nokey_refcnt)) 388 goto unlock_child; 389 390 psk = ask->parent; 391 pask = alg_sk(ask->parent); 392 tfm = pask->private; 393 394 err = -ENOKEY; 395 lock_sock_nested(psk, SINGLE_DEPTH_NESTING); 396 if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) 397 goto unlock; 398 399 atomic_dec(&pask->nokey_refcnt); 400 atomic_set(&ask->nokey_refcnt, 0); 401 402 err = 0; 403 404unlock: 405 release_sock(psk); 406unlock_child: 407 release_sock(sk); 408 409 return err; 410} 411 412static int aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg, 413 size_t size) 414{ 415 int err; 416 417 err = aead_check_key(sock); 418 if (err) 419 return err; 420 421 return aead_sendmsg(sock, msg, size); 422} 423 424static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg, 425 size_t ignored, int flags) 426{ 427 int err; 428 429 err = aead_check_key(sock); 430 if (err) 431 return err; 432 433 return aead_recvmsg(sock, msg, ignored, flags); 434} 435 436static struct proto_ops algif_aead_ops_nokey = { 437 .family = PF_ALG, 438 439 .connect = sock_no_connect, 440 .socketpair = sock_no_socketpair, 441 .getname = sock_no_getname, 442 .ioctl = sock_no_ioctl, 443 .listen = sock_no_listen, 444 .shutdown = sock_no_shutdown, 445 .mmap = sock_no_mmap, 446 .bind = sock_no_bind, 447 .accept = sock_no_accept, 448 449 .release = af_alg_release, 450 .sendmsg = aead_sendmsg_nokey, 451 .recvmsg = aead_recvmsg_nokey, 452 .poll = af_alg_poll, 453}; 454 455static void *aead_bind(const char *name, u32 type, u32 mask) 456{ 457 struct aead_tfm *tfm; 458 struct crypto_aead *aead; 459 struct crypto_sync_skcipher *null_tfm; 460 461 tfm = kzalloc(sizeof(*tfm), GFP_KERNEL); 462 if (!tfm) 463 return ERR_PTR(-ENOMEM); 464 465 aead = crypto_alloc_aead(name, type, mask); 466 if (IS_ERR(aead)) { 467 kfree(tfm); 468 return ERR_CAST(aead); 469 } 470 471 null_tfm = crypto_get_default_null_skcipher(); 472 if (IS_ERR(null_tfm)) { 473 crypto_free_aead(aead); 474 kfree(tfm); 475 return ERR_CAST(null_tfm); 476 } 477 478 tfm->aead = aead; 479 tfm->null_tfm = null_tfm; 480 481 return tfm; 482} 483 484static void aead_release(void *private) 485{ 486 struct aead_tfm *tfm = private; 487 488 crypto_free_aead(tfm->aead); 489 crypto_put_default_null_skcipher(); 490 kfree(tfm); 491} 492 493static int aead_setauthsize(void *private, unsigned int authsize) 494{ 495 struct aead_tfm *tfm = private; 496 497 return crypto_aead_setauthsize(tfm->aead, authsize); 498} 499 500static int aead_setkey(void *private, const u8 *key, unsigned int keylen) 501{ 502 struct aead_tfm *tfm = private; 503 504 return crypto_aead_setkey(tfm->aead, key, keylen); 505} 506 507static void aead_sock_destruct(struct sock *sk) 508{ 509 struct alg_sock *ask = alg_sk(sk); 510 struct af_alg_ctx *ctx = ask->private; 511 struct sock *psk = ask->parent; 512 struct alg_sock *pask = alg_sk(psk); 513 struct aead_tfm *aeadc = pask->private; 514 struct crypto_aead *tfm = aeadc->aead; 515 unsigned int ivlen = crypto_aead_ivsize(tfm); 516 517 af_alg_pull_tsgl(sk, ctx->used, NULL, 0); 518 sock_kzfree_s(sk, ctx->iv, ivlen); 519 sock_kfree_s(sk, ctx, ctx->len); 520 af_alg_release_parent(sk); 521} 522 523static int aead_accept_parent_nokey(void *private, struct sock *sk) 524{ 525 struct af_alg_ctx *ctx; 526 struct alg_sock *ask = alg_sk(sk); 527 struct aead_tfm *tfm = private; 528 struct crypto_aead *aead = tfm->aead; 529 unsigned int len = sizeof(*ctx); 530 unsigned int ivlen = crypto_aead_ivsize(aead); 531 532 ctx = sock_kmalloc(sk, len, GFP_KERNEL); 533 if (!ctx) 534 return -ENOMEM; 535 memset(ctx, 0, len); 536 537 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL); 538 if (!ctx->iv) { 539 sock_kfree_s(sk, ctx, len); 540 return -ENOMEM; 541 } 542 memset(ctx->iv, 0, ivlen); 543 544 INIT_LIST_HEAD(&ctx->tsgl_list); 545 ctx->len = len; 546 crypto_init_wait(&ctx->wait); 547 548 ask->private = ctx; 549 550 sk->sk_destruct = aead_sock_destruct; 551 552 return 0; 553} 554 555static int aead_accept_parent(void *private, struct sock *sk) 556{ 557 struct aead_tfm *tfm = private; 558 559 if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY) 560 return -ENOKEY; 561 562 return aead_accept_parent_nokey(private, sk); 563} 564 565static const struct af_alg_type algif_type_aead = { 566 .bind = aead_bind, 567 .release = aead_release, 568 .setkey = aead_setkey, 569 .setauthsize = aead_setauthsize, 570 .accept = aead_accept_parent, 571 .accept_nokey = aead_accept_parent_nokey, 572 .ops = &algif_aead_ops, 573 .ops_nokey = &algif_aead_ops_nokey, 574 .name = "aead", 575 .owner = THIS_MODULE 576}; 577 578static int __init algif_aead_init(void) 579{ 580 return af_alg_register_type(&algif_type_aead); 581} 582 583static void __exit algif_aead_exit(void) 584{ 585 int err = af_alg_unregister_type(&algif_type_aead); 586 BUG_ON(err); 587} 588 589module_init(algif_aead_init); 590module_exit(algif_aead_exit); 591MODULE_LICENSE("GPL"); 592MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>"); 593MODULE_DESCRIPTION("AEAD kernel crypto API user space interface"); 594