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