1 /* 2 * algif_skcipher: User-space interface for skcipher algorithms 3 * 4 * This file provides the user-space API for symmetric key ciphers. 5 * 6 * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the Free 10 * Software Foundation; either version 2 of the License, or (at your option) 11 * any later version. 12 * 13 */ 14 15 #include <crypto/scatterwalk.h> 16 #include <crypto/skcipher.h> 17 #include <crypto/if_alg.h> 18 #include <linux/init.h> 19 #include <linux/list.h> 20 #include <linux/kernel.h> 21 #include <linux/mm.h> 22 #include <linux/module.h> 23 #include <linux/net.h> 24 #include <net/sock.h> 25 26 struct skcipher_sg_list { 27 struct list_head list; 28 29 int cur; 30 31 struct scatterlist sg[0]; 32 }; 33 34 struct skcipher_ctx { 35 struct list_head tsgl; 36 struct af_alg_sgl rsgl; 37 38 void *iv; 39 40 struct af_alg_completion completion; 41 42 unsigned used; 43 44 unsigned int len; 45 bool more; 46 bool merge; 47 bool enc; 48 49 struct ablkcipher_request req; 50 }; 51 52 #define MAX_SGL_ENTS ((4096 - sizeof(struct skcipher_sg_list)) / \ 53 sizeof(struct scatterlist) - 1) 54 55 static inline int skcipher_sndbuf(struct sock *sk) 56 { 57 struct alg_sock *ask = alg_sk(sk); 58 struct skcipher_ctx *ctx = ask->private; 59 60 return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) - 61 ctx->used, 0); 62 } 63 64 static inline bool skcipher_writable(struct sock *sk) 65 { 66 return PAGE_SIZE <= skcipher_sndbuf(sk); 67 } 68 69 static int skcipher_alloc_sgl(struct sock *sk) 70 { 71 struct alg_sock *ask = alg_sk(sk); 72 struct skcipher_ctx *ctx = ask->private; 73 struct skcipher_sg_list *sgl; 74 struct scatterlist *sg = NULL; 75 76 sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list); 77 if (!list_empty(&ctx->tsgl)) 78 sg = sgl->sg; 79 80 if (!sg || sgl->cur >= MAX_SGL_ENTS) { 81 sgl = sock_kmalloc(sk, sizeof(*sgl) + 82 sizeof(sgl->sg[0]) * (MAX_SGL_ENTS + 1), 83 GFP_KERNEL); 84 if (!sgl) 85 return -ENOMEM; 86 87 sg_init_table(sgl->sg, MAX_SGL_ENTS + 1); 88 sgl->cur = 0; 89 90 if (sg) 91 scatterwalk_sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg); 92 93 list_add_tail(&sgl->list, &ctx->tsgl); 94 } 95 96 return 0; 97 } 98 99 static void skcipher_pull_sgl(struct sock *sk, int used) 100 { 101 struct alg_sock *ask = alg_sk(sk); 102 struct skcipher_ctx *ctx = ask->private; 103 struct skcipher_sg_list *sgl; 104 struct scatterlist *sg; 105 int i; 106 107 while (!list_empty(&ctx->tsgl)) { 108 sgl = list_first_entry(&ctx->tsgl, struct skcipher_sg_list, 109 list); 110 sg = sgl->sg; 111 112 for (i = 0; i < sgl->cur; i++) { 113 int plen = min_t(int, used, sg[i].length); 114 115 if (!sg_page(sg + i)) 116 continue; 117 118 sg[i].length -= plen; 119 sg[i].offset += plen; 120 121 used -= plen; 122 ctx->used -= plen; 123 124 if (sg[i].length) 125 return; 126 127 put_page(sg_page(sg + i)); 128 sg_assign_page(sg + i, NULL); 129 } 130 131 list_del(&sgl->list); 132 sock_kfree_s(sk, sgl, 133 sizeof(*sgl) + sizeof(sgl->sg[0]) * 134 (MAX_SGL_ENTS + 1)); 135 } 136 137 if (!ctx->used) 138 ctx->merge = 0; 139 } 140 141 static void skcipher_free_sgl(struct sock *sk) 142 { 143 struct alg_sock *ask = alg_sk(sk); 144 struct skcipher_ctx *ctx = ask->private; 145 146 skcipher_pull_sgl(sk, ctx->used); 147 } 148 149 static int skcipher_wait_for_wmem(struct sock *sk, unsigned flags) 150 { 151 long timeout; 152 DEFINE_WAIT(wait); 153 int err = -ERESTARTSYS; 154 155 if (flags & MSG_DONTWAIT) 156 return -EAGAIN; 157 158 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); 159 160 for (;;) { 161 if (signal_pending(current)) 162 break; 163 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); 164 timeout = MAX_SCHEDULE_TIMEOUT; 165 if (sk_wait_event(sk, &timeout, skcipher_writable(sk))) { 166 err = 0; 167 break; 168 } 169 } 170 finish_wait(sk_sleep(sk), &wait); 171 172 return err; 173 } 174 175 static void skcipher_wmem_wakeup(struct sock *sk) 176 { 177 struct socket_wq *wq; 178 179 if (!skcipher_writable(sk)) 180 return; 181 182 rcu_read_lock(); 183 wq = rcu_dereference(sk->sk_wq); 184 if (wq_has_sleeper(wq)) 185 wake_up_interruptible_sync_poll(&wq->wait, POLLIN | 186 POLLRDNORM | 187 POLLRDBAND); 188 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); 189 rcu_read_unlock(); 190 } 191 192 static int skcipher_wait_for_data(struct sock *sk, unsigned flags) 193 { 194 struct alg_sock *ask = alg_sk(sk); 195 struct skcipher_ctx *ctx = ask->private; 196 long timeout; 197 DEFINE_WAIT(wait); 198 int err = -ERESTARTSYS; 199 200 if (flags & MSG_DONTWAIT) { 201 return -EAGAIN; 202 } 203 204 set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); 205 206 for (;;) { 207 if (signal_pending(current)) 208 break; 209 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); 210 timeout = MAX_SCHEDULE_TIMEOUT; 211 if (sk_wait_event(sk, &timeout, ctx->used)) { 212 err = 0; 213 break; 214 } 215 } 216 finish_wait(sk_sleep(sk), &wait); 217 218 clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags); 219 220 return err; 221 } 222 223 static void skcipher_data_wakeup(struct sock *sk) 224 { 225 struct alg_sock *ask = alg_sk(sk); 226 struct skcipher_ctx *ctx = ask->private; 227 struct socket_wq *wq; 228 229 if (!ctx->used) 230 return; 231 232 rcu_read_lock(); 233 wq = rcu_dereference(sk->sk_wq); 234 if (wq_has_sleeper(wq)) 235 wake_up_interruptible_sync_poll(&wq->wait, POLLOUT | 236 POLLRDNORM | 237 POLLRDBAND); 238 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); 239 rcu_read_unlock(); 240 } 241 242 static int skcipher_sendmsg(struct kiocb *unused, struct socket *sock, 243 struct msghdr *msg, size_t size) 244 { 245 struct sock *sk = sock->sk; 246 struct alg_sock *ask = alg_sk(sk); 247 struct skcipher_ctx *ctx = ask->private; 248 struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req); 249 unsigned ivsize = crypto_ablkcipher_ivsize(tfm); 250 struct skcipher_sg_list *sgl; 251 struct af_alg_control con = {}; 252 long copied = 0; 253 bool enc = 0; 254 bool init = 0; 255 int err; 256 int i; 257 258 if (msg->msg_controllen) { 259 err = af_alg_cmsg_send(msg, &con); 260 if (err) 261 return err; 262 263 init = 1; 264 switch (con.op) { 265 case ALG_OP_ENCRYPT: 266 enc = 1; 267 break; 268 case ALG_OP_DECRYPT: 269 enc = 0; 270 break; 271 default: 272 return -EINVAL; 273 } 274 275 if (con.iv && con.iv->ivlen != ivsize) 276 return -EINVAL; 277 } 278 279 err = -EINVAL; 280 281 lock_sock(sk); 282 if (!ctx->more && ctx->used) 283 goto unlock; 284 285 if (init) { 286 ctx->enc = enc; 287 if (con.iv) 288 memcpy(ctx->iv, con.iv->iv, ivsize); 289 } 290 291 while (size) { 292 struct scatterlist *sg; 293 unsigned long len = size; 294 int plen; 295 296 if (ctx->merge) { 297 sgl = list_entry(ctx->tsgl.prev, 298 struct skcipher_sg_list, list); 299 sg = sgl->sg + sgl->cur - 1; 300 len = min_t(unsigned long, len, 301 PAGE_SIZE - sg->offset - sg->length); 302 303 err = memcpy_from_msg(page_address(sg_page(sg)) + 304 sg->offset + sg->length, 305 msg, len); 306 if (err) 307 goto unlock; 308 309 sg->length += len; 310 ctx->merge = (sg->offset + sg->length) & 311 (PAGE_SIZE - 1); 312 313 ctx->used += len; 314 copied += len; 315 size -= len; 316 continue; 317 } 318 319 if (!skcipher_writable(sk)) { 320 err = skcipher_wait_for_wmem(sk, msg->msg_flags); 321 if (err) 322 goto unlock; 323 } 324 325 len = min_t(unsigned long, len, skcipher_sndbuf(sk)); 326 327 err = skcipher_alloc_sgl(sk); 328 if (err) 329 goto unlock; 330 331 sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list); 332 sg = sgl->sg; 333 sg_unmark_end(sg + sgl->cur); 334 do { 335 i = sgl->cur; 336 plen = min_t(int, len, PAGE_SIZE); 337 338 sg_assign_page(sg + i, alloc_page(GFP_KERNEL)); 339 err = -ENOMEM; 340 if (!sg_page(sg + i)) 341 goto unlock; 342 343 err = memcpy_from_msg(page_address(sg_page(sg + i)), 344 msg, plen); 345 if (err) { 346 __free_page(sg_page(sg + i)); 347 sg_assign_page(sg + i, NULL); 348 goto unlock; 349 } 350 351 sg[i].length = plen; 352 len -= plen; 353 ctx->used += plen; 354 copied += plen; 355 size -= plen; 356 sgl->cur++; 357 } while (len && sgl->cur < MAX_SGL_ENTS); 358 359 if (!size) 360 sg_mark_end(sg + sgl->cur - 1); 361 362 ctx->merge = plen & (PAGE_SIZE - 1); 363 } 364 365 err = 0; 366 367 ctx->more = msg->msg_flags & MSG_MORE; 368 369 unlock: 370 skcipher_data_wakeup(sk); 371 release_sock(sk); 372 373 return copied ?: err; 374 } 375 376 static ssize_t skcipher_sendpage(struct socket *sock, struct page *page, 377 int offset, size_t size, int flags) 378 { 379 struct sock *sk = sock->sk; 380 struct alg_sock *ask = alg_sk(sk); 381 struct skcipher_ctx *ctx = ask->private; 382 struct skcipher_sg_list *sgl; 383 int err = -EINVAL; 384 385 if (flags & MSG_SENDPAGE_NOTLAST) 386 flags |= MSG_MORE; 387 388 lock_sock(sk); 389 if (!ctx->more && ctx->used) 390 goto unlock; 391 392 if (!size) 393 goto done; 394 395 if (!skcipher_writable(sk)) { 396 err = skcipher_wait_for_wmem(sk, flags); 397 if (err) 398 goto unlock; 399 } 400 401 err = skcipher_alloc_sgl(sk); 402 if (err) 403 goto unlock; 404 405 ctx->merge = 0; 406 sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list); 407 408 if (sgl->cur) 409 sg_unmark_end(sgl->sg + sgl->cur - 1); 410 411 sg_mark_end(sgl->sg + sgl->cur); 412 get_page(page); 413 sg_set_page(sgl->sg + sgl->cur, page, size, offset); 414 sgl->cur++; 415 ctx->used += size; 416 417 done: 418 ctx->more = flags & MSG_MORE; 419 420 unlock: 421 skcipher_data_wakeup(sk); 422 release_sock(sk); 423 424 return err ?: size; 425 } 426 427 static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock, 428 struct msghdr *msg, size_t ignored, int flags) 429 { 430 struct sock *sk = sock->sk; 431 struct alg_sock *ask = alg_sk(sk); 432 struct skcipher_ctx *ctx = ask->private; 433 unsigned bs = crypto_ablkcipher_blocksize(crypto_ablkcipher_reqtfm( 434 &ctx->req)); 435 struct skcipher_sg_list *sgl; 436 struct scatterlist *sg; 437 int err = -EAGAIN; 438 int used; 439 long copied = 0; 440 441 lock_sock(sk); 442 while (iov_iter_count(&msg->msg_iter)) { 443 sgl = list_first_entry(&ctx->tsgl, 444 struct skcipher_sg_list, list); 445 sg = sgl->sg; 446 447 while (!sg->length) 448 sg++; 449 450 if (!ctx->used) { 451 err = skcipher_wait_for_data(sk, flags); 452 if (err) 453 goto unlock; 454 } 455 456 used = min_t(unsigned long, ctx->used, iov_iter_count(&msg->msg_iter)); 457 458 used = af_alg_make_sg(&ctx->rsgl, &msg->msg_iter, used); 459 err = used; 460 if (err < 0) 461 goto unlock; 462 463 if (ctx->more || used < ctx->used) 464 used -= used % bs; 465 466 err = -EINVAL; 467 if (!used) 468 goto free; 469 470 ablkcipher_request_set_crypt(&ctx->req, sg, 471 ctx->rsgl.sg, used, 472 ctx->iv); 473 474 err = af_alg_wait_for_completion( 475 ctx->enc ? 476 crypto_ablkcipher_encrypt(&ctx->req) : 477 crypto_ablkcipher_decrypt(&ctx->req), 478 &ctx->completion); 479 480 free: 481 af_alg_free_sg(&ctx->rsgl); 482 483 if (err) 484 goto unlock; 485 486 copied += used; 487 skcipher_pull_sgl(sk, used); 488 iov_iter_advance(&msg->msg_iter, used); 489 } 490 491 err = 0; 492 493 unlock: 494 skcipher_wmem_wakeup(sk); 495 release_sock(sk); 496 497 return copied ?: err; 498 } 499 500 501 static unsigned int skcipher_poll(struct file *file, struct socket *sock, 502 poll_table *wait) 503 { 504 struct sock *sk = sock->sk; 505 struct alg_sock *ask = alg_sk(sk); 506 struct skcipher_ctx *ctx = ask->private; 507 unsigned int mask; 508 509 sock_poll_wait(file, sk_sleep(sk), wait); 510 mask = 0; 511 512 if (ctx->used) 513 mask |= POLLIN | POLLRDNORM; 514 515 if (skcipher_writable(sk)) 516 mask |= POLLOUT | POLLWRNORM | POLLWRBAND; 517 518 return mask; 519 } 520 521 static struct proto_ops algif_skcipher_ops = { 522 .family = PF_ALG, 523 524 .connect = sock_no_connect, 525 .socketpair = sock_no_socketpair, 526 .getname = sock_no_getname, 527 .ioctl = sock_no_ioctl, 528 .listen = sock_no_listen, 529 .shutdown = sock_no_shutdown, 530 .getsockopt = sock_no_getsockopt, 531 .mmap = sock_no_mmap, 532 .bind = sock_no_bind, 533 .accept = sock_no_accept, 534 .setsockopt = sock_no_setsockopt, 535 536 .release = af_alg_release, 537 .sendmsg = skcipher_sendmsg, 538 .sendpage = skcipher_sendpage, 539 .recvmsg = skcipher_recvmsg, 540 .poll = skcipher_poll, 541 }; 542 543 static void *skcipher_bind(const char *name, u32 type, u32 mask) 544 { 545 return crypto_alloc_ablkcipher(name, type, mask); 546 } 547 548 static void skcipher_release(void *private) 549 { 550 crypto_free_ablkcipher(private); 551 } 552 553 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) 554 { 555 return crypto_ablkcipher_setkey(private, key, keylen); 556 } 557 558 static void skcipher_sock_destruct(struct sock *sk) 559 { 560 struct alg_sock *ask = alg_sk(sk); 561 struct skcipher_ctx *ctx = ask->private; 562 struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req); 563 564 skcipher_free_sgl(sk); 565 sock_kzfree_s(sk, ctx->iv, crypto_ablkcipher_ivsize(tfm)); 566 sock_kfree_s(sk, ctx, ctx->len); 567 af_alg_release_parent(sk); 568 } 569 570 static int skcipher_accept_parent(void *private, struct sock *sk) 571 { 572 struct skcipher_ctx *ctx; 573 struct alg_sock *ask = alg_sk(sk); 574 unsigned int len = sizeof(*ctx) + crypto_ablkcipher_reqsize(private); 575 576 ctx = sock_kmalloc(sk, len, GFP_KERNEL); 577 if (!ctx) 578 return -ENOMEM; 579 580 ctx->iv = sock_kmalloc(sk, crypto_ablkcipher_ivsize(private), 581 GFP_KERNEL); 582 if (!ctx->iv) { 583 sock_kfree_s(sk, ctx, len); 584 return -ENOMEM; 585 } 586 587 memset(ctx->iv, 0, crypto_ablkcipher_ivsize(private)); 588 589 INIT_LIST_HEAD(&ctx->tsgl); 590 ctx->len = len; 591 ctx->used = 0; 592 ctx->more = 0; 593 ctx->merge = 0; 594 ctx->enc = 0; 595 af_alg_init_completion(&ctx->completion); 596 597 ask->private = ctx; 598 599 ablkcipher_request_set_tfm(&ctx->req, private); 600 ablkcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG, 601 af_alg_complete, &ctx->completion); 602 603 sk->sk_destruct = skcipher_sock_destruct; 604 605 return 0; 606 } 607 608 static const struct af_alg_type algif_type_skcipher = { 609 .bind = skcipher_bind, 610 .release = skcipher_release, 611 .setkey = skcipher_setkey, 612 .accept = skcipher_accept_parent, 613 .ops = &algif_skcipher_ops, 614 .name = "skcipher", 615 .owner = THIS_MODULE 616 }; 617 618 static int __init algif_skcipher_init(void) 619 { 620 return af_alg_register_type(&algif_type_skcipher); 621 } 622 623 static void __exit algif_skcipher_exit(void) 624 { 625 int err = af_alg_unregister_type(&algif_type_skcipher); 626 BUG_ON(err); 627 } 628 629 module_init(algif_skcipher_init); 630 module_exit(algif_skcipher_exit); 631 MODULE_LICENSE("GPL"); 632