crypto/algif_aead.c

   1 /*
   2  * algif_aead: User-space interface for AEAD algorithms
   3  *
   4  * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
   5  *
   6  * This file provides the user-space API for AEAD ciphers.
   7  *
   8  * This file is derived from algif_skcipher.c.
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  */
  15
  16 #include <crypto/aead.h>
  17 #include <crypto/scatterwalk.h>
  18 #include <crypto/if_alg.h>
  19 #include <linux/init.h>
  20 #include <linux/list.h>
  21 #include <linux/kernel.h>
  22 #include <linux/mm.h>
  23 #include <linux/module.h>
  24 #include <linux/net.h>
  25 #include <net/sock.h>
  26
  27 struct aead_sg_list {
  28         unsigned int cur;
  29         struct scatterlist sg[ALG_MAX_PAGES];
  30 };
  31
  32 struct aead_ctx {
  33         struct aead_sg_list tsgl;
  34         /*
  35          * RSGL_MAX_ENTRIES is an artificial limit where user space at maximum
  36          * can cause the kernel to allocate RSGL_MAX_ENTRIES * ALG_MAX_PAGES
  37          * pages
  38          */
  39 #define RSGL_MAX_ENTRIES ALG_MAX_PAGES
  40         struct af_alg_sgl rsgl[RSGL_MAX_ENTRIES];
  41
  42         void *iv;
  43
  44         struct af_alg_completion completion;
  45
  46         unsigned long used;
  47
  48         unsigned int len;
  49         bool more;
  50         bool merge;
  51         bool enc;
  52
  53         size_t aead_assoclen;
  54         struct aead_request aead_req;
  55 };
  56
  57 static inline int aead_sndbuf(struct sock *sk)
  58 {
  59         struct alg_sock *ask = alg_sk(sk);
  60         struct aead_ctx *ctx = ask->private;
  61
  62         return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
  63                           ctx->used, 0);
  64 }
  65
  66 static inline bool aead_writable(struct sock *sk)
  67 {
  68         return PAGE_SIZE <= aead_sndbuf(sk);
  69 }
  70
  71 static inline bool aead_sufficient_data(struct aead_ctx *ctx)
  72 {
  73         unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
  74
  75         return ctx->used >= ctx->aead_assoclen + as;
  76 }
  77
  78 static void aead_put_sgl(struct sock *sk)
  79 {
  80         struct alg_sock *ask = alg_sk(sk);
  81         struct aead_ctx *ctx = ask->private;
  82         struct aead_sg_list *sgl = &ctx->tsgl;
  83         struct scatterlist *sg = sgl->sg;
  84         unsigned int i;
  85
  86         for (i = 0; i < sgl->cur; i++) {
  87                 if (!sg_page(sg + i))
  88                         continue;
  89
  90                 put_page(sg_page(sg + i));
  91                 sg_assign_page(sg + i, NULL);
  92         }
  93         sg_init_table(sg, ALG_MAX_PAGES);
  94         sgl->cur = 0;
  95         ctx->used = 0;
  96         ctx->more = 0;
  97         ctx->merge = 0;
  98 }
  99
 100 static void aead_wmem_wakeup(struct sock *sk)
 101 {
 102         struct socket_wq *wq;
 103
 104         if (!aead_writable(sk))
 105                 return;
 106
 107         rcu_read_lock();
 108         wq = rcu_dereference(sk->sk_wq);
 109         if (skwq_has_sleeper(wq))
 110                 wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
 111                                                            POLLRDNORM |
 112                                                            POLLRDBAND);
 113         sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
 114         rcu_read_unlock();
 115 }
 116
 117 static int aead_wait_for_data(struct sock *sk, unsigned flags)
 118 {
 119         struct alg_sock *ask = alg_sk(sk);
 120         struct aead_ctx *ctx = ask->private;
 121         long timeout;
 122         DEFINE_WAIT(wait);
 123         int err = -ERESTARTSYS;
 124
 125         if (flags & MSG_DONTWAIT)
 126                 return -EAGAIN;
 127
 128         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 129
 130         for (;;) {
 131                 if (signal_pending(current))
 132                         break;
 133                 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
 134                 timeout = MAX_SCHEDULE_TIMEOUT;
 135                 if (sk_wait_event(sk, &timeout, !ctx->more)) {
 136                         err = 0;
 137                         break;
 138                 }
 139         }
 140         finish_wait(sk_sleep(sk), &wait);
 141
 142         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 143
 144         return err;
 145 }
 146
 147 static void aead_data_wakeup(struct sock *sk)
 148 {
 149         struct alg_sock *ask = alg_sk(sk);
 150         struct aead_ctx *ctx = ask->private;
 151         struct socket_wq *wq;
 152
 153         if (ctx->more)
 154                 return;
 155         if (!ctx->used)
 156                 return;
 157
 158         rcu_read_lock();
 159         wq = rcu_dereference(sk->sk_wq);
 160         if (skwq_has_sleeper(wq))
 161                 wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
 162                                                            POLLRDNORM |
 163                                                            POLLRDBAND);
 164         sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
 165         rcu_read_unlock();
 166 }
 167
 168 static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 169 {
 170         struct sock *sk = sock->sk;
 171         struct alg_sock *ask = alg_sk(sk);
 172         struct aead_ctx *ctx = ask->private;
 173         unsigned ivsize =
 174                 crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req));
 175         struct aead_sg_list *sgl = &ctx->tsgl;
 176         struct af_alg_control con = {};
 177         long copied = 0;
 178         bool enc = 0;
 179         bool init = 0;
 180         int err = -EINVAL;
 181
 182         if (msg->msg_controllen) {
 183                 err = af_alg_cmsg_send(msg, &con);
 184                 if (err)
 185                         return err;
 186
 187                 init = 1;
 188                 switch (con.op) {
 189                 case ALG_OP_ENCRYPT:
 190                         enc = 1;
 191                         break;
 192                 case ALG_OP_DECRYPT:
 193                         enc = 0;
 194                         break;
 195                 default:
 196                         return -EINVAL;
 197                 }
 198
 199                 if (con.iv && con.iv->ivlen != ivsize)
 200                         return -EINVAL;
 201         }
 202
 203         lock_sock(sk);
 204         if (!ctx->more && ctx->used)
 205                 goto unlock;
 206
 207         if (init) {
 208                 ctx->enc = enc;
 209                 if (con.iv)
 210                         memcpy(ctx->iv, con.iv->iv, ivsize);
 211
 212                 ctx->aead_assoclen = con.aead_assoclen;
 213         }
 214
 215         while (size) {
 216                 size_t len = size;
 217                 struct scatterlist *sg = NULL;
 218
 219                 /* use the existing memory in an allocated page */
 220                 if (ctx->merge) {
 221                         sg = sgl->sg + sgl->cur - 1;
 222                         len = min_t(unsigned long, len,
 223                                     PAGE_SIZE - sg->offset - sg->length);
 224                         err = memcpy_from_msg(page_address(sg_page(sg)) +
 225                                               sg->offset + sg->length,
 226                                               msg, len);
 227                         if (err)
 228                                 goto unlock;
 229
 230                         sg->length += len;
 231                         ctx->merge = (sg->offset + sg->length) &
 232                                      (PAGE_SIZE - 1);
 233
 234                         ctx->used += len;
 235                         copied += len;
 236                         size -= len;
 237                         continue;
 238                 }
 239
 240                 if (!aead_writable(sk)) {
 241                         /* user space sent too much data */
 242                         aead_put_sgl(sk);
 243                         err = -EMSGSIZE;
 244                         goto unlock;
 245                 }
 246
 247                 /* allocate a new page */
 248                 len = min_t(unsigned long, size, aead_sndbuf(sk));
 249                 while (len) {
 250                         size_t plen = 0;
 251
 252                         if (sgl->cur >= ALG_MAX_PAGES) {
 253                                 aead_put_sgl(sk);
 254                                 err = -E2BIG;
 255                                 goto unlock;
 256                         }
 257
 258                         sg = sgl->sg + sgl->cur;
 259                         plen = min_t(size_t, len, PAGE_SIZE);
 260
 261                         sg_assign_page(sg, alloc_page(GFP_KERNEL));
 262                         err = -ENOMEM;
 263                         if (!sg_page(sg))
 264                                 goto unlock;
 265
 266                         err = memcpy_from_msg(page_address(sg_page(sg)),
 267                                               msg, plen);
 268                         if (err) {
 269                                 __free_page(sg_page(sg));
 270                                 sg_assign_page(sg, NULL);
 271                                 goto unlock;
 272                         }
 273
 274                         sg->offset = 0;
 275                         sg->length = plen;
 276                         len -= plen;
 277                         ctx->used += plen;
 278                         copied += plen;
 279                         sgl->cur++;
 280                         size -= plen;
 281                         ctx->merge = plen & (PAGE_SIZE - 1);
 282                 }
 283         }
 284
 285         err = 0;
 286
 287         ctx->more = msg->msg_flags & MSG_MORE;
 288         if (!ctx->more && !aead_sufficient_data(ctx)) {
 289                 aead_put_sgl(sk);
 290                 err = -EMSGSIZE;
 291         }
 292
 293 unlock:
 294         aead_data_wakeup(sk);
 295         release_sock(sk);
 296
 297         return err ?: copied;
 298 }
 299
 300 static ssize_t aead_sendpage(struct socket *sock, struct page *page,
 301                              int offset, size_t size, int flags)
 302 {
 303         struct sock *sk = sock->sk;
 304         struct alg_sock *ask = alg_sk(sk);
 305         struct aead_ctx *ctx = ask->private;
 306         struct aead_sg_list *sgl = &ctx->tsgl;
 307         int err = -EINVAL;
 308
 309         if (flags & MSG_SENDPAGE_NOTLAST)
 310                 flags |= MSG_MORE;
 311
 312         if (sgl->cur >= ALG_MAX_PAGES)
 313                 return -E2BIG;
 314
 315         lock_sock(sk);
 316         if (!ctx->more && ctx->used)
 317                 goto unlock;
 318
 319         if (!size)
 320                 goto done;
 321
 322         if (!aead_writable(sk)) {
 323                 /* user space sent too much data */
 324                 aead_put_sgl(sk);
 325                 err = -EMSGSIZE;
 326                 goto unlock;
 327         }
 328
 329         ctx->merge = 0;
 330
 331         get_page(page);
 332         sg_set_page(sgl->sg + sgl->cur, page, size, offset);
 333         sgl->cur++;
 334         ctx->used += size;
 335
 336         err = 0;
 337
 338 done:
 339         ctx->more = flags & MSG_MORE;
 340         if (!ctx->more && !aead_sufficient_data(ctx)) {
 341                 aead_put_sgl(sk);
 342                 err = -EMSGSIZE;
 343         }
 344
 345 unlock:
 346         aead_data_wakeup(sk);
 347         release_sock(sk);
 348
 349         return err ?: size;
 350 }
 351
 352 static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored, int flags)
 353 {
 354         struct sock *sk = sock->sk;
 355         struct alg_sock *ask = alg_sk(sk);
 356         struct aead_ctx *ctx = ask->private;
 357         unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
 358         struct aead_sg_list *sgl = &ctx->tsgl;
 359         unsigned int i = 0;
 360         int err = -EINVAL;
 361         unsigned long used = 0;
 362         size_t outlen = 0;
 363         size_t usedpages = 0;
 364         unsigned int cnt = 0;
 365
 366         /* Limit number of IOV blocks to be accessed below */
 367         if (msg->msg_iter.nr_segs > RSGL_MAX_ENTRIES)
 368                 return -ENOMSG;
 369
 370         lock_sock(sk);
 371
 372         /*
 373          * AEAD memory structure: For encryption, the tag is appended to the
 374          * ciphertext which implies that the memory allocated for the ciphertext
 375          * must be increased by the tag length. For decryption, the tag
 376          * is expected to be concatenated to the ciphertext. The plaintext
 377          * therefore has a memory size of the ciphertext minus the tag length.
 378          *
 379          * The memory structure for cipher operation has the following
 380          * structure:
 381          *      AEAD encryption input:  assoc data || plaintext
 382          *      AEAD encryption output: cipherntext || auth tag
 383          *      AEAD decryption input:  assoc data || ciphertext || auth tag
 384          *      AEAD decryption output: plaintext
 385          */
 386
 387         if (ctx->more) {
 388                 err = aead_wait_for_data(sk, flags);
 389                 if (err)
 390                         goto unlock;
 391         }
 392
 393         used = ctx->used;
 394
 395         /*
 396          * Make sure sufficient data is present -- note, the same check is
 397          * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg
 398          * shall provide an information to the data sender that something is
 399          * wrong, but they are irrelevant to maintain the kernel integrity.
 400          * We need this check here too in case user space decides to not honor
 401          * the error message in sendmsg/sendpage and still call recvmsg. This
 402          * check here protects the kernel integrity.
 403          */
 404         if (!aead_sufficient_data(ctx))
 405                 goto unlock;
 406
 407         outlen = used;
 408
 409         /*
 410          * The cipher operation input data is reduced by the associated data
 411          * length as this data is processed separately later on.
 412          */
 413         used -= ctx->aead_assoclen + (ctx->enc ? as : 0);
 414
 415         /* convert iovecs of output buffers into scatterlists */
 416         while (iov_iter_count(&msg->msg_iter)) {
 417                 size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
 418                                       (outlen - usedpages));
 419
 420                 /* make one iovec available as scatterlist */
 421                 err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter,
 422                                      seglen);
 423                 if (err < 0)
 424                         goto unlock;
 425                 usedpages += err;
 426                 /* chain the new scatterlist with previous one */
 427                 if (cnt)
 428                         af_alg_link_sg(&ctx->rsgl[cnt-1], &ctx->rsgl[cnt]);
 429
 430                 /* we do not need more iovecs as we have sufficient memory */
 431                 if (outlen <= usedpages)
 432                         break;
 433                 iov_iter_advance(&msg->msg_iter, err);
 434                 cnt++;
 435         }
 436
 437         err = -EINVAL;
 438         /* ensure output buffer is sufficiently large */
 439         if (usedpages < outlen)
 440                 goto unlock;
 441
 442         sg_mark_end(sgl->sg + sgl->cur - 1);
 443
 444         aead_request_set_crypt(&ctx->aead_req, sgl->sg, ctx->rsgl[0].sg,
 445                                used, ctx->iv);
 446         aead_request_set_ad(&ctx->aead_req, ctx->aead_assoclen);
 447
 448         err = af_alg_wait_for_completion(ctx->enc ?
 449                                          crypto_aead_encrypt(&ctx->aead_req) :
 450                                          crypto_aead_decrypt(&ctx->aead_req),
 451                                          &ctx->completion);
 452
 453         if (err) {
 454                 /* EBADMSG implies a valid cipher operation took place */
 455                 if (err == -EBADMSG)
 456                         aead_put_sgl(sk);
 457                 goto unlock;
 458         }
 459
 460         aead_put_sgl(sk);
 461
 462         err = 0;
 463
 464 unlock:
 465         for (i = 0; i < cnt; i++)
 466                 af_alg_free_sg(&ctx->rsgl[i]);
 467
 468         aead_wmem_wakeup(sk);
 469         release_sock(sk);
 470
 471         return err ? err : outlen;
 472 }
 473
 474 static unsigned int aead_poll(struct file *file, struct socket *sock,
 475                               poll_table *wait)
 476 {
 477         struct sock *sk = sock->sk;
 478         struct alg_sock *ask = alg_sk(sk);
 479         struct aead_ctx *ctx = ask->private;
 480         unsigned int mask;
 481
 482         sock_poll_wait(file, sk_sleep(sk), wait);
 483         mask = 0;
 484
 485         if (!ctx->more)
 486                 mask |= POLLIN | POLLRDNORM;
 487
 488         if (aead_writable(sk))
 489                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
 490
 491         return mask;
 492 }
 493
 494 static struct proto_ops algif_aead_ops = {
 495         .family         =       PF_ALG,
 496
 497         .connect        =       sock_no_connect,
 498         .socketpair     =       sock_no_socketpair,
 499         .getname        =       sock_no_getname,
 500         .ioctl          =       sock_no_ioctl,
 501         .listen         =       sock_no_listen,
 502         .shutdown       =       sock_no_shutdown,
 503         .getsockopt     =       sock_no_getsockopt,
 504         .mmap           =       sock_no_mmap,
 505         .bind           =       sock_no_bind,
 506         .accept         =       sock_no_accept,
 507         .setsockopt     =       sock_no_setsockopt,
 508
 509         .release        =       af_alg_release,
 510         .sendmsg        =       aead_sendmsg,
 511         .sendpage       =       aead_sendpage,
 512         .recvmsg        =       aead_recvmsg,
 513         .poll           =       aead_poll,
 514 };
 515
 516 static void *aead_bind(const char *name, u32 type, u32 mask)
 517 {
 518         return crypto_alloc_aead(name, type, mask);
 519 }
 520
 521 static void aead_release(void *private)
 522 {
 523         crypto_free_aead(private);
 524 }
 525
 526 static int aead_setauthsize(void *private, unsigned int authsize)
 527 {
 528         return crypto_aead_setauthsize(private, authsize);
 529 }
 530
 531 static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
 532 {
 533         return crypto_aead_setkey(private, key, keylen);
 534 }
 535
 536 static void aead_sock_destruct(struct sock *sk)
 537 {
 538         struct alg_sock *ask = alg_sk(sk);
 539         struct aead_ctx *ctx = ask->private;
 540         unsigned int ivlen = crypto_aead_ivsize(
 541                                 crypto_aead_reqtfm(&ctx->aead_req));
 542
 543         aead_put_sgl(sk);
 544         sock_kzfree_s(sk, ctx->iv, ivlen);
 545         sock_kfree_s(sk, ctx, ctx->len);
 546         af_alg_release_parent(sk);
 547 }
 548
 549 static int aead_accept_parent(void *private, struct sock *sk)
 550 {
 551         struct aead_ctx *ctx;
 552         struct alg_sock *ask = alg_sk(sk);
 553         unsigned int len = sizeof(*ctx) + crypto_aead_reqsize(private);
 554         unsigned int ivlen = crypto_aead_ivsize(private);
 555
 556         ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 557         if (!ctx)
 558                 return -ENOMEM;
 559         memset(ctx, 0, len);
 560
 561         ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
 562         if (!ctx->iv) {
 563                 sock_kfree_s(sk, ctx, len);
 564                 return -ENOMEM;
 565         }
 566         memset(ctx->iv, 0, ivlen);
 567
 568         ctx->len = len;
 569         ctx->used = 0;
 570         ctx->more = 0;
 571         ctx->merge = 0;
 572         ctx->enc = 0;
 573         ctx->tsgl.cur = 0;
 574         ctx->aead_assoclen = 0;
 575         af_alg_init_completion(&ctx->completion);
 576         sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
 577
 578         ask->private = ctx;
 579
 580         aead_request_set_tfm(&ctx->aead_req, private);
 581         aead_request_set_callback(&ctx->aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
 582                                   af_alg_complete, &ctx->completion);
 583
 584         sk->sk_destruct = aead_sock_destruct;
 585
 586         return 0;
 587 }
 588
 589 static const struct af_alg_type algif_type_aead = {
 590         .bind           =       aead_bind,
 591         .release        =       aead_release,
 592         .setkey         =       aead_setkey,
 593         .setauthsize    =       aead_setauthsize,
 594         .accept         =       aead_accept_parent,
 595         .ops            =       &algif_aead_ops,
 596         .name           =       "aead",
 597         .owner          =       THIS_MODULE
 598 };
 599
 600 static int __init algif_aead_init(void)
 601 {
 602         return af_alg_register_type(&algif_type_aead);
 603 }
 604
 605 static void __exit algif_aead_exit(void)
 606 {
 607         int err = af_alg_unregister_type(&algif_type_aead);
 608         BUG_ON(err);
 609 }
 610
 611 module_init(algif_aead_init);
 612 module_exit(algif_aead_exit);
 613 MODULE_LICENSE("GPL");
 614 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
 615 MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");