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 static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
  42                             size_t size)
  43 {
  44         struct sock *sk = sock->sk;
  45         struct alg_sock *ask = alg_sk(sk);
  46         struct sock *psk = ask->parent;
  47         struct alg_sock *pask = alg_sk(psk);
  48         struct crypto_skcipher *tfm = pask->private;
  49         unsigned ivsize = crypto_skcipher_ivsize(tfm);
  50
  51         return af_alg_sendmsg(sock, msg, size, ivsize);
  52 }
  53
  54 static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
  55                              size_t ignored, int flags)
  56 {
  57         struct sock *sk = sock->sk;
  58         struct alg_sock *ask = alg_sk(sk);
  59         struct sock *psk = ask->parent;
  60         struct alg_sock *pask = alg_sk(psk);
  61         struct af_alg_ctx *ctx = ask->private;
  62         struct crypto_skcipher *tfm = pask->private;
  63         unsigned int bs = crypto_skcipher_blocksize(tfm);
  64         struct af_alg_async_req *areq;
  65         int err = 0;
  66         size_t len = 0;
  67
  68         if (!ctx->used) {
  69                 err = af_alg_wait_for_data(sk, flags);
  70                 if (err)
  71                         return err;
  72         }
  73
  74         /* Allocate cipher request for current operation. */
  75         areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
  76                                      crypto_skcipher_reqsize(tfm));
  77         if (IS_ERR(areq))
  78                 return PTR_ERR(areq);
  79
  80         /* convert iovecs of output buffers into RX SGL */
  81         err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
  82         if (err)
  83                 goto free;
  84
  85         /* Process only as much RX buffers for which we have TX data */
  86         if (len > ctx->used)
  87                 len = ctx->used;
  88
  89         /*
  90          * If more buffers are to be expected to be processed, process only
  91          * full block size buffers.
  92          */
  93         if (ctx->more || len < ctx->used)
  94                 len -= len % bs;
  95
  96         /*
  97          * Create a per request TX SGL for this request which tracks the
  98          * SG entries from the global TX SGL.
  99          */
 100         areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
 101         if (!areq->tsgl_entries)
 102                 areq->tsgl_entries = 1;
 103         areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
 104                                                  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
 123                 /* Remember output size that will be generated. */
 124                 areq->outlen = len;
 125
 126                 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
 127                                               CRYPTO_TFM_REQ_MAY_SLEEP,
 128                                               af_alg_async_cb, areq);
 129                 err = ctx->enc ?
 130                         crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
 131                         crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
 132
 133                 /* AIO operation in progress */
 134                 if (err == -EINPROGRESS || err == -EBUSY)
 135                         return -EIOCBQUEUED;
 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 static struct proto_ops algif_skcipher_ops = {
 191         .family         =       PF_ALG,
 192
 193         .connect        =       sock_no_connect,
 194         .socketpair     =       sock_no_socketpair,
 195         .getname        =       sock_no_getname,
 196         .ioctl          =       sock_no_ioctl,
 197         .listen         =       sock_no_listen,
 198         .shutdown       =       sock_no_shutdown,
 199         .getsockopt     =       sock_no_getsockopt,
 200         .mmap           =       sock_no_mmap,
 201         .bind           =       sock_no_bind,
 202         .accept         =       sock_no_accept,
 203         .setsockopt     =       sock_no_setsockopt,
 204
 205         .release        =       af_alg_release,
 206         .sendmsg        =       skcipher_sendmsg,
 207         .sendpage       =       af_alg_sendpage,
 208         .recvmsg        =       skcipher_recvmsg,
 209         .poll           =       af_alg_poll,
 210 };
 211
 212 static int skcipher_check_key(struct socket *sock)
 213 {
 214         int err = 0;
 215         struct sock *psk;
 216         struct alg_sock *pask;
 217         struct crypto_skcipher *tfm;
 218         struct sock *sk = sock->sk;
 219         struct alg_sock *ask = alg_sk(sk);
 220
 221         lock_sock(sk);
 222         if (ask->refcnt)
 223                 goto unlock_child;
 224
 225         psk = ask->parent;
 226         pask = alg_sk(ask->parent);
 227         tfm = pask->private;
 228
 229         err = -ENOKEY;
 230         lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
 231         if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 232                 goto unlock;
 233
 234         if (!pask->refcnt++)
 235                 sock_hold(psk);
 236
 237         ask->refcnt = 1;
 238         sock_put(psk);
 239
 240         err = 0;
 241
 242 unlock:
 243         release_sock(psk);
 244 unlock_child:
 245         release_sock(sk);
 246
 247         return err;
 248 }
 249
 250 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
 251                                   size_t size)
 252 {
 253         int err;
 254
 255         err = skcipher_check_key(sock);
 256         if (err)
 257                 return err;
 258
 259         return skcipher_sendmsg(sock, msg, size);
 260 }
 261
 262 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
 263                                        int offset, size_t size, int flags)
 264 {
 265         int err;
 266
 267         err = skcipher_check_key(sock);
 268         if (err)
 269                 return err;
 270
 271         return af_alg_sendpage(sock, page, offset, size, flags);
 272 }
 273
 274 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
 275                                   size_t ignored, int flags)
 276 {
 277         int err;
 278
 279         err = skcipher_check_key(sock);
 280         if (err)
 281                 return err;
 282
 283         return skcipher_recvmsg(sock, msg, ignored, flags);
 284 }
 285
 286 static struct proto_ops algif_skcipher_ops_nokey = {
 287         .family         =       PF_ALG,
 288
 289         .connect        =       sock_no_connect,
 290         .socketpair     =       sock_no_socketpair,
 291         .getname        =       sock_no_getname,
 292         .ioctl          =       sock_no_ioctl,
 293         .listen         =       sock_no_listen,
 294         .shutdown       =       sock_no_shutdown,
 295         .getsockopt     =       sock_no_getsockopt,
 296         .mmap           =       sock_no_mmap,
 297         .bind           =       sock_no_bind,
 298         .accept         =       sock_no_accept,
 299         .setsockopt     =       sock_no_setsockopt,
 300
 301         .release        =       af_alg_release,
 302         .sendmsg        =       skcipher_sendmsg_nokey,
 303         .sendpage       =       skcipher_sendpage_nokey,
 304         .recvmsg        =       skcipher_recvmsg_nokey,
 305         .poll           =       af_alg_poll,
 306 };
 307
 308 static void *skcipher_bind(const char *name, u32 type, u32 mask)
 309 {
 310         return crypto_alloc_skcipher(name, type, mask);
 311 }
 312
 313 static void skcipher_release(void *private)
 314 {
 315         crypto_free_skcipher(private);
 316 }
 317
 318 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
 319 {
 320         return crypto_skcipher_setkey(private, key, keylen);
 321 }
 322
 323 static void skcipher_sock_destruct(struct sock *sk)
 324 {
 325         struct alg_sock *ask = alg_sk(sk);
 326         struct af_alg_ctx *ctx = ask->private;
 327         struct sock *psk = ask->parent;
 328         struct alg_sock *pask = alg_sk(psk);
 329         struct crypto_skcipher *tfm = pask->private;
 330
 331         af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
 332         sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
 333         sock_kfree_s(sk, ctx, ctx->len);
 334         af_alg_release_parent(sk);
 335 }
 336
 337 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
 338 {
 339         struct af_alg_ctx *ctx;
 340         struct alg_sock *ask = alg_sk(sk);
 341         struct crypto_skcipher *tfm = private;
 342         unsigned int len = sizeof(*ctx);
 343
 344         ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 345         if (!ctx)
 346                 return -ENOMEM;
 347
 348         ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
 349                                GFP_KERNEL);
 350         if (!ctx->iv) {
 351                 sock_kfree_s(sk, ctx, len);
 352                 return -ENOMEM;
 353         }
 354
 355         memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
 356
 357         INIT_LIST_HEAD(&ctx->tsgl_list);
 358         ctx->len = len;
 359         ctx->used = 0;
 360         atomic_set(&ctx->rcvused, 0);
 361         ctx->more = 0;
 362         ctx->merge = 0;
 363         ctx->enc = 0;
 364         crypto_init_wait(&ctx->wait);
 365
 366         ask->private = ctx;
 367
 368         sk->sk_destruct = skcipher_sock_destruct;
 369
 370         return 0;
 371 }
 372
 373 static int skcipher_accept_parent(void *private, struct sock *sk)
 374 {
 375         struct crypto_skcipher *tfm = private;
 376
 377         if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 378                 return -ENOKEY;
 379
 380         return skcipher_accept_parent_nokey(private, sk);
 381 }
 382
 383 static const struct af_alg_type algif_type_skcipher = {
 384         .bind           =       skcipher_bind,
 385         .release        =       skcipher_release,
 386         .setkey         =       skcipher_setkey,
 387         .accept         =       skcipher_accept_parent,
 388         .accept_nokey   =       skcipher_accept_parent_nokey,
 389         .ops            =       &algif_skcipher_ops,
 390         .ops_nokey      =       &algif_skcipher_ops_nokey,
 391         .name           =       "skcipher",
 392         .owner          =       THIS_MODULE
 393 };
 394
 395 static int __init algif_skcipher_init(void)
 396 {
 397         return af_alg_register_type(&algif_type_skcipher);
 398 }
 399
 400 static void __exit algif_skcipher_exit(void)
 401 {
 402         int err = af_alg_unregister_type(&algif_type_skcipher);
 403         BUG_ON(err);
 404 }
 405
 406 module_init(algif_skcipher_init);
 407 module_exit(algif_skcipher_exit);
 408 MODULE_LICENSE("GPL");