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  * The following concept of the memory management is used:
  14  *
  15  * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is
  16  * filled by user space with the data submitted via sendpage/sendmsg. Filling
  17  * up the TX SGL does not cause a crypto operation -- the data will only be
  18  * tracked by the kernel. Upon receipt of one recvmsg call, the caller must
  19  * provide a buffer which is tracked with the RX SGL.
  20  *
  21  * During the processing of the recvmsg operation, the cipher request is
  22  * allocated and prepared. As part of the recvmsg operation, the processed
  23  * TX buffers are extracted from the TX SGL into a separate SGL.
  24  *
  25  * After the completion of the crypto operation, the RX SGL and the cipher
  26  * request is released. The extracted TX SGL parts are released together with
  27  * the RX SGL release.
  28  */
  29
  30 #include <crypto/scatterwalk.h>
  31 #include <crypto/skcipher.h>
  32 #include <crypto/if_alg.h>
  33 #include <linux/init.h>
  34 #include <linux/list.h>
  35 #include <linux/kernel.h>
  36 #include <linux/mm.h>
  37 #include <linux/module.h>
  38 #include <linux/net.h>
  39 #include <net/sock.h>
  40
  41 struct skcipher_tfm {
  42         struct crypto_skcipher *skcipher;
  43         bool has_key;
  44 };
  45
  46 static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
  47                             size_t size)
  48 {
  49         struct sock *sk = sock->sk;
  50         struct alg_sock *ask = alg_sk(sk);
  51         struct sock *psk = ask->parent;
  52         struct alg_sock *pask = alg_sk(psk);
  53         struct skcipher_tfm *skc = pask->private;
  54         struct crypto_skcipher *tfm = skc->skcipher;
  55         unsigned ivsize = crypto_skcipher_ivsize(tfm);
  56
  57         return af_alg_sendmsg(sock, msg, size, ivsize);
  58 }
  59
  60 static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
  61                              size_t ignored, int flags)
  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 af_alg_ctx *ctx = ask->private;
  68         struct skcipher_tfm *skc = pask->private;
  69         struct crypto_skcipher *tfm = skc->skcipher;
  70         unsigned int bs = crypto_skcipher_blocksize(tfm);
  71         struct af_alg_async_req *areq;
  72         int err = 0;
  73         size_t len = 0;
  74
  75         if (!ctx->used) {
  76                 err = af_alg_wait_for_data(sk, flags);
  77                 if (err)
  78                         return err;
  79         }
  80
  81         /* Allocate cipher request for current operation. */
  82         areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
  83                                      crypto_skcipher_reqsize(tfm));
  84         if (IS_ERR(areq))
  85                 return PTR_ERR(areq);
  86
  87         /* convert iovecs of output buffers into RX SGL */
  88         err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
  89         if (err)
  90                 goto free;
  91
  92         /* Process only as much RX buffers for which we have TX data */
  93         if (len > ctx->used)
  94                 len = ctx->used;
  95
  96         /*
  97          * If more buffers are to be expected to be processed, process only
  98          * full block size buffers.
  99          */
 100         if (ctx->more || len < ctx->used)
 101                 len -= len % bs;
 102
 103         /*
 104          * Create a per request TX SGL for this request which tracks the
 105          * SG entries from the global TX SGL.
 106          */
 107         areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
 108         if (!areq->tsgl_entries)
 109                 areq->tsgl_entries = 1;
 110         areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) * areq->tsgl_entries,
 111                                   GFP_KERNEL);
 112         if (!areq->tsgl) {
 113                 err = -ENOMEM;
 114                 goto free;
 115         }
 116         sg_init_table(areq->tsgl, areq->tsgl_entries);
 117         af_alg_pull_tsgl(sk, len, areq->tsgl, 0);
 118
 119         /* Initialize the crypto operation */
 120         skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
 121         skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
 122                                    areq->first_rsgl.sgl.sg, len, ctx->iv);
 123
 124         if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
 125                 /* AIO operation */
 126                 sock_hold(sk);
 127                 areq->iocb = msg->msg_iocb;
 128
 129                 /* Remember output size that will be generated. */
 130                 areq->outlen = len;
 131
 132                 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
 133                                               CRYPTO_TFM_REQ_MAY_SLEEP,
 134                                               af_alg_async_cb, areq);
 135                 err = ctx->enc ?
 136                         crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
 137                         crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
 138
 139                 /* AIO operation in progress */
 140                 if (err == -EINPROGRESS || err == -EBUSY)
 141                         return -EIOCBQUEUED;
 142
 143                 sock_put(sk);
 144         } else {
 145                 /* Synchronous operation */
 146                 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
 147                                               CRYPTO_TFM_REQ_MAY_SLEEP |
 148                                               CRYPTO_TFM_REQ_MAY_BACKLOG,
 149                                               crypto_req_done, &ctx->wait);
 150                 err = crypto_wait_req(ctx->enc ?
 151                         crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
 152                         crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
 153                                                  &ctx->wait);
 154         }
 155
 156
 157 free:
 158         af_alg_free_resources(areq);
 159
 160         return err ? err : len;
 161 }
 162
 163 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 164                             size_t ignored, int flags)
 165 {
 166         struct sock *sk = sock->sk;
 167         int ret = 0;
 168
 169         lock_sock(sk);
 170         while (msg_data_left(msg)) {
 171                 int err = _skcipher_recvmsg(sock, msg, ignored, flags);
 172
 173                 /*
 174                  * This error covers -EIOCBQUEUED which implies that we can
 175                  * only handle one AIO request. If the caller wants to have
 176                  * multiple AIO requests in parallel, he must make multiple
 177                  * separate AIO calls.
 178                  *
 179                  * Also return the error if no data has been processed so far.
 180                  */
 181                 if (err <= 0) {
 182                         if (err == -EIOCBQUEUED || !ret)
 183                                 ret = err;
 184                         goto out;
 185                 }
 186
 187                 ret += err;
 188         }
 189
 190 out:
 191         af_alg_wmem_wakeup(sk);
 192         release_sock(sk);
 193         return ret;
 194 }
 195
 196
 197 static struct proto_ops algif_skcipher_ops = {
 198         .family         =       PF_ALG,
 199
 200         .connect        =       sock_no_connect,
 201         .socketpair     =       sock_no_socketpair,
 202         .getname        =       sock_no_getname,
 203         .ioctl          =       sock_no_ioctl,
 204         .listen         =       sock_no_listen,
 205         .shutdown       =       sock_no_shutdown,
 206         .getsockopt     =       sock_no_getsockopt,
 207         .mmap           =       sock_no_mmap,
 208         .bind           =       sock_no_bind,
 209         .accept         =       sock_no_accept,
 210         .setsockopt     =       sock_no_setsockopt,
 211
 212         .release        =       af_alg_release,
 213         .sendmsg        =       skcipher_sendmsg,
 214         .sendpage       =       af_alg_sendpage,
 215         .recvmsg        =       skcipher_recvmsg,
 216         .poll           =       af_alg_poll,
 217 };
 218
 219 static int skcipher_check_key(struct socket *sock)
 220 {
 221         int err = 0;
 222         struct sock *psk;
 223         struct alg_sock *pask;
 224         struct skcipher_tfm *tfm;
 225         struct sock *sk = sock->sk;
 226         struct alg_sock *ask = alg_sk(sk);
 227
 228         lock_sock(sk);
 229         if (ask->refcnt)
 230                 goto unlock_child;
 231
 232         psk = ask->parent;
 233         pask = alg_sk(ask->parent);
 234         tfm = pask->private;
 235
 236         err = -ENOKEY;
 237         lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
 238         if (!tfm->has_key)
 239                 goto unlock;
 240
 241         if (!pask->refcnt++)
 242                 sock_hold(psk);
 243
 244         ask->refcnt = 1;
 245         sock_put(psk);
 246
 247         err = 0;
 248
 249 unlock:
 250         release_sock(psk);
 251 unlock_child:
 252         release_sock(sk);
 253
 254         return err;
 255 }
 256
 257 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
 258                                   size_t size)
 259 {
 260         int err;
 261
 262         err = skcipher_check_key(sock);
 263         if (err)
 264                 return err;
 265
 266         return skcipher_sendmsg(sock, msg, size);
 267 }
 268
 269 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
 270                                        int offset, size_t size, int flags)
 271 {
 272         int err;
 273
 274         err = skcipher_check_key(sock);
 275         if (err)
 276                 return err;
 277
 278         return af_alg_sendpage(sock, page, offset, size, flags);
 279 }
 280
 281 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
 282                                   size_t ignored, int flags)
 283 {
 284         int err;
 285
 286         err = skcipher_check_key(sock);
 287         if (err)
 288                 return err;
 289
 290         return skcipher_recvmsg(sock, msg, ignored, flags);
 291 }
 292
 293 static struct proto_ops algif_skcipher_ops_nokey = {
 294         .family         =       PF_ALG,
 295
 296         .connect        =       sock_no_connect,
 297         .socketpair     =       sock_no_socketpair,
 298         .getname        =       sock_no_getname,
 299         .ioctl          =       sock_no_ioctl,
 300         .listen         =       sock_no_listen,
 301         .shutdown       =       sock_no_shutdown,
 302         .getsockopt     =       sock_no_getsockopt,
 303         .mmap           =       sock_no_mmap,
 304         .bind           =       sock_no_bind,
 305         .accept         =       sock_no_accept,
 306         .setsockopt     =       sock_no_setsockopt,
 307
 308         .release        =       af_alg_release,
 309         .sendmsg        =       skcipher_sendmsg_nokey,
 310         .sendpage       =       skcipher_sendpage_nokey,
 311         .recvmsg        =       skcipher_recvmsg_nokey,
 312         .poll           =       af_alg_poll,
 313 };
 314
 315 static void *skcipher_bind(const char *name, u32 type, u32 mask)
 316 {
 317         struct skcipher_tfm *tfm;
 318         struct crypto_skcipher *skcipher;
 319
 320         tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
 321         if (!tfm)
 322                 return ERR_PTR(-ENOMEM);
 323
 324         skcipher = crypto_alloc_skcipher(name, type, mask);
 325         if (IS_ERR(skcipher)) {
 326                 kfree(tfm);
 327                 return ERR_CAST(skcipher);
 328         }
 329
 330         tfm->skcipher = skcipher;
 331
 332         return tfm;
 333 }
 334
 335 static void skcipher_release(void *private)
 336 {
 337         struct skcipher_tfm *tfm = private;
 338
 339         crypto_free_skcipher(tfm->skcipher);
 340         kfree(tfm);
 341 }
 342
 343 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
 344 {
 345         struct skcipher_tfm *tfm = private;
 346         int err;
 347
 348         err = crypto_skcipher_setkey(tfm->skcipher, key, keylen);
 349         tfm->has_key = !err;
 350
 351         return err;
 352 }
 353
 354 static void skcipher_sock_destruct(struct sock *sk)
 355 {
 356         struct alg_sock *ask = alg_sk(sk);
 357         struct af_alg_ctx *ctx = ask->private;
 358         struct sock *psk = ask->parent;
 359         struct alg_sock *pask = alg_sk(psk);
 360         struct skcipher_tfm *skc = pask->private;
 361         struct crypto_skcipher *tfm = skc->skcipher;
 362
 363         af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
 364         sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
 365         sock_kfree_s(sk, ctx, ctx->len);
 366         af_alg_release_parent(sk);
 367 }
 368
 369 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
 370 {
 371         struct af_alg_ctx *ctx;
 372         struct alg_sock *ask = alg_sk(sk);
 373         struct skcipher_tfm *tfm = private;
 374         struct crypto_skcipher *skcipher = tfm->skcipher;
 375         unsigned int len = sizeof(*ctx);
 376
 377         ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 378         if (!ctx)
 379                 return -ENOMEM;
 380
 381         ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(skcipher),
 382                                GFP_KERNEL);
 383         if (!ctx->iv) {
 384                 sock_kfree_s(sk, ctx, len);
 385                 return -ENOMEM;
 386         }
 387
 388         memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher));
 389
 390         INIT_LIST_HEAD(&ctx->tsgl_list);
 391         ctx->len = len;
 392         ctx->used = 0;
 393         atomic_set(&ctx->rcvused, 0);
 394         ctx->more = 0;
 395         ctx->merge = 0;
 396         ctx->enc = 0;
 397         crypto_init_wait(&ctx->wait);
 398
 399         ask->private = ctx;
 400
 401         sk->sk_destruct = skcipher_sock_destruct;
 402
 403         return 0;
 404 }
 405
 406 static int skcipher_accept_parent(void *private, struct sock *sk)
 407 {
 408         struct skcipher_tfm *tfm = private;
 409
 410         if (!tfm->has_key && crypto_skcipher_has_setkey(tfm->skcipher))
 411                 return -ENOKEY;
 412
 413         return skcipher_accept_parent_nokey(private, sk);
 414 }
 415
 416 static const struct af_alg_type algif_type_skcipher = {
 417         .bind           =       skcipher_bind,
 418         .release        =       skcipher_release,
 419         .setkey         =       skcipher_setkey,
 420         .accept         =       skcipher_accept_parent,
 421         .accept_nokey   =       skcipher_accept_parent_nokey,
 422         .ops            =       &algif_skcipher_ops,
 423         .ops_nokey      =       &algif_skcipher_ops_nokey,
 424         .name           =       "skcipher",
 425         .owner          =       THIS_MODULE
 426 };
 427
 428 static int __init algif_skcipher_init(void)
 429 {
 430         return af_alg_register_type(&algif_type_skcipher);
 431 }
 432
 433 static void __exit algif_skcipher_exit(void)
 434 {
 435         int err = af_alg_unregister_type(&algif_type_skcipher);
 436         BUG_ON(err);
 437 }
 438
 439 module_init(algif_skcipher_init);
 440 module_exit(algif_skcipher_exit);
 441 MODULE_LICENSE("GPL");