crypto/algif_skcipher.c

   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");