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