crypto/algif_skcipher.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * algif_skcipher: User-space interface for skcipher algorithms
   4  *
   5  * This file provides the user-space API for symmetric key ciphers.
   6  *
   7  * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * The following concept of the memory management is used:
  10  *
  11  * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is
  12  * filled by user space with the data submitted via sendmsg. Filling up the TX
  13  * SGL does not cause a crypto operation -- the data will only be tracked by
  14  * the kernel. Upon receipt of one recvmsg call, the caller must provide a
  15  * buffer which is tracked with the RX SGL.
  16  *
  17  * During the processing of the recvmsg operation, the cipher request is
  18  * allocated and prepared. As part of the recvmsg operation, the processed
  19  * TX buffers are extracted from the TX SGL into a separate SGL.
  20  *
  21  * After the completion of the crypto operation, the RX SGL and the cipher
  22  * request is released. The extracted TX SGL parts are released together with
  23  * the RX SGL release.
  24  */
  25
  26 #include <crypto/scatterwalk.h>
  27 #include <crypto/skcipher.h>
  28 #include <crypto/if_alg.h>
  29 #include <linux/init.h>
  30 #include <linux/list.h>
  31 #include <linux/kernel.h>
  32 #include <linux/mm.h>
  33 #include <linux/module.h>
  34 #include <linux/net.h>
  35 #include <net/sock.h>
  36
  37 static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
  38                             size_t size)
  39 {
  40         struct sock *sk = sock->sk;
  41         struct alg_sock *ask = alg_sk(sk);
  42         struct sock *psk = ask->parent;
  43         struct alg_sock *pask = alg_sk(psk);
  44         struct crypto_skcipher *tfm = pask->private;
  45         unsigned ivsize = crypto_skcipher_ivsize(tfm);
  46
  47         return af_alg_sendmsg(sock, msg, size, ivsize);
  48 }
  49
  50 static int algif_skcipher_export(struct sock *sk, struct skcipher_request *req)
  51 {
  52         struct alg_sock *ask = alg_sk(sk);
  53         struct crypto_skcipher *tfm;
  54         struct af_alg_ctx *ctx;
  55         struct alg_sock *pask;
  56         unsigned statesize;
  57         struct sock *psk;
  58         int err;
  59
  60         if (!(req->base.flags & CRYPTO_SKCIPHER_REQ_NOTFINAL))
  61                 return 0;
  62
  63         ctx = ask->private;
  64         psk = ask->parent;
  65         pask = alg_sk(psk);
  66         tfm = pask->private;
  67
  68         statesize = crypto_skcipher_statesize(tfm);
  69         ctx->state = sock_kmalloc(sk, statesize, GFP_ATOMIC);
  70         if (!ctx->state)
  71                 return -ENOMEM;
  72
  73         err = crypto_skcipher_export(req, ctx->state);
  74         if (err) {
  75                 sock_kzfree_s(sk, ctx->state, statesize);
  76                 ctx->state = NULL;
  77         }
  78
  79         return err;
  80 }
  81
  82 static void algif_skcipher_done(void *data, int err)
  83 {
  84         struct af_alg_async_req *areq = data;
  85         struct sock *sk = areq->sk;
  86
  87         if (err)
  88                 goto out;
  89
  90         err = algif_skcipher_export(sk, &areq->cra_u.skcipher_req);
  91
  92 out:
  93         af_alg_async_cb(data, err);
  94 }
  95
  96 static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
  97                              size_t ignored, int flags)
  98 {
  99         struct sock *sk = sock->sk;
 100         struct alg_sock *ask = alg_sk(sk);
 101         struct sock *psk = ask->parent;
 102         struct alg_sock *pask = alg_sk(psk);
 103         struct af_alg_ctx *ctx = ask->private;
 104         struct crypto_skcipher *tfm = pask->private;
 105         unsigned int bs = crypto_skcipher_chunksize(tfm);
 106         struct af_alg_async_req *areq;
 107         unsigned cflags = 0;
 108         int err = 0;
 109         size_t len = 0;
 110
 111         if (!ctx->init || (ctx->more && ctx->used < bs)) {
 112                 err = af_alg_wait_for_data(sk, flags, bs);
 113                 if (err)
 114                         return err;
 115         }
 116
 117         /* Allocate cipher request for current operation. */
 118         areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
 119                                      crypto_skcipher_reqsize(tfm));
 120         if (IS_ERR(areq))
 121                 return PTR_ERR(areq);
 122
 123         /* convert iovecs of output buffers into RX SGL */
 124         err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
 125         if (err)
 126                 goto free;
 127
 128         /*
 129          * If more buffers are to be expected to be processed, process only
 130          * full block size buffers.
 131          */
 132         if (ctx->more || len < ctx->used) {
 133                 len -= len % bs;
 134                 cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL;
 135         }
 136
 137         /*
 138          * Create a per request TX SGL for this request which tracks the
 139          * SG entries from the global TX SGL.
 140          */
 141         areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
 142         if (!areq->tsgl_entries)
 143                 areq->tsgl_entries = 1;
 144         areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
 145                                                  areq->tsgl_entries),
 146                                   GFP_KERNEL);
 147         if (!areq->tsgl) {
 148                 err = -ENOMEM;
 149                 goto free;
 150         }
 151         sg_init_table(areq->tsgl, areq->tsgl_entries);
 152         af_alg_pull_tsgl(sk, len, areq->tsgl, 0);
 153
 154         /* Initialize the crypto operation */
 155         skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
 156         skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
 157                                    areq->first_rsgl.sgl.sgt.sgl, len, ctx->iv);
 158
 159         if (ctx->state) {
 160                 err = crypto_skcipher_import(&areq->cra_u.skcipher_req,
 161                                              ctx->state);
 162                 sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
 163                 ctx->state = NULL;
 164                 if (err)
 165                         goto free;
 166                 cflags |= CRYPTO_SKCIPHER_REQ_CONT;
 167         }
 168
 169         if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
 170                 /* AIO operation */
 171                 sock_hold(sk);
 172                 areq->iocb = msg->msg_iocb;
 173
 174                 /* Remember output size that will be generated. */
 175                 areq->outlen = len;
 176
 177                 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
 178                                               cflags |
 179                                               CRYPTO_TFM_REQ_MAY_SLEEP,
 180                                               algif_skcipher_done, areq);
 181                 err = ctx->enc ?
 182                         crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
 183                         crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
 184
 185                 /* AIO operation in progress */
 186                 if (err == -EINPROGRESS)
 187                         return -EIOCBQUEUED;
 188
 189                 sock_put(sk);
 190         } else {
 191                 /* Synchronous operation */
 192                 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
 193                                               cflags |
 194                                               CRYPTO_TFM_REQ_MAY_SLEEP |
 195                                               CRYPTO_TFM_REQ_MAY_BACKLOG,
 196                                               crypto_req_done, &ctx->wait);
 197                 err = crypto_wait_req(ctx->enc ?
 198                         crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
 199                         crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
 200                                                  &ctx->wait);
 201
 202                 if (!err)
 203                         err = algif_skcipher_export(
 204                                 sk, &areq->cra_u.skcipher_req);
 205         }
 206
 207 free:
 208         af_alg_free_resources(areq);
 209
 210         return err ? err : len;
 211 }
 212
 213 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 214                             size_t ignored, int flags)
 215 {
 216         struct sock *sk = sock->sk;
 217         int ret = 0;
 218
 219         lock_sock(sk);
 220         while (msg_data_left(msg)) {
 221                 int err = _skcipher_recvmsg(sock, msg, ignored, flags);
 222
 223                 /*
 224                  * This error covers -EIOCBQUEUED which implies that we can
 225                  * only handle one AIO request. If the caller wants to have
 226                  * multiple AIO requests in parallel, he must make multiple
 227                  * separate AIO calls.
 228                  *
 229                  * Also return the error if no data has been processed so far.
 230                  */
 231                 if (err <= 0) {
 232                         if (err == -EIOCBQUEUED || !ret)
 233                                 ret = err;
 234                         goto out;
 235                 }
 236
 237                 ret += err;
 238         }
 239
 240 out:
 241         af_alg_wmem_wakeup(sk);
 242         release_sock(sk);
 243         return ret;
 244 }
 245
 246 static struct proto_ops algif_skcipher_ops = {
 247         .family         =       PF_ALG,
 248
 249         .connect        =       sock_no_connect,
 250         .socketpair     =       sock_no_socketpair,
 251         .getname        =       sock_no_getname,
 252         .ioctl          =       sock_no_ioctl,
 253         .listen         =       sock_no_listen,
 254         .shutdown       =       sock_no_shutdown,
 255         .mmap           =       sock_no_mmap,
 256         .bind           =       sock_no_bind,
 257         .accept         =       sock_no_accept,
 258
 259         .release        =       af_alg_release,
 260         .sendmsg        =       skcipher_sendmsg,
 261         .recvmsg        =       skcipher_recvmsg,
 262         .poll           =       af_alg_poll,
 263 };
 264
 265 static int skcipher_check_key(struct socket *sock)
 266 {
 267         int err = 0;
 268         struct sock *psk;
 269         struct alg_sock *pask;
 270         struct crypto_skcipher *tfm;
 271         struct sock *sk = sock->sk;
 272         struct alg_sock *ask = alg_sk(sk);
 273
 274         lock_sock(sk);
 275         if (!atomic_read(&ask->nokey_refcnt))
 276                 goto unlock_child;
 277
 278         psk = ask->parent;
 279         pask = alg_sk(ask->parent);
 280         tfm = pask->private;
 281
 282         err = -ENOKEY;
 283         lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
 284         if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 285                 goto unlock;
 286
 287         atomic_dec(&pask->nokey_refcnt);
 288         atomic_set(&ask->nokey_refcnt, 0);
 289
 290         err = 0;
 291
 292 unlock:
 293         release_sock(psk);
 294 unlock_child:
 295         release_sock(sk);
 296
 297         return err;
 298 }
 299
 300 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
 301                                   size_t size)
 302 {
 303         int err;
 304
 305         err = skcipher_check_key(sock);
 306         if (err)
 307                 return err;
 308
 309         return skcipher_sendmsg(sock, msg, size);
 310 }
 311
 312 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
 313                                   size_t ignored, int flags)
 314 {
 315         int err;
 316
 317         err = skcipher_check_key(sock);
 318         if (err)
 319                 return err;
 320
 321         return skcipher_recvmsg(sock, msg, ignored, flags);
 322 }
 323
 324 static struct proto_ops algif_skcipher_ops_nokey = {
 325         .family         =       PF_ALG,
 326
 327         .connect        =       sock_no_connect,
 328         .socketpair     =       sock_no_socketpair,
 329         .getname        =       sock_no_getname,
 330         .ioctl          =       sock_no_ioctl,
 331         .listen         =       sock_no_listen,
 332         .shutdown       =       sock_no_shutdown,
 333         .mmap           =       sock_no_mmap,
 334         .bind           =       sock_no_bind,
 335         .accept         =       sock_no_accept,
 336
 337         .release        =       af_alg_release,
 338         .sendmsg        =       skcipher_sendmsg_nokey,
 339         .recvmsg        =       skcipher_recvmsg_nokey,
 340         .poll           =       af_alg_poll,
 341 };
 342
 343 static void *skcipher_bind(const char *name, u32 type, u32 mask)
 344 {
 345         return crypto_alloc_skcipher(name, type, mask);
 346 }
 347
 348 static void skcipher_release(void *private)
 349 {
 350         crypto_free_skcipher(private);
 351 }
 352
 353 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
 354 {
 355         return crypto_skcipher_setkey(private, key, keylen);
 356 }
 357
 358 static void skcipher_sock_destruct(struct sock *sk)
 359 {
 360         struct alg_sock *ask = alg_sk(sk);
 361         struct af_alg_ctx *ctx = ask->private;
 362         struct sock *psk = ask->parent;
 363         struct alg_sock *pask = alg_sk(psk);
 364         struct crypto_skcipher *tfm = pask->private;
 365
 366         af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
 367         sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
 368         if (ctx->state)
 369                 sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
 370         sock_kfree_s(sk, ctx, ctx->len);
 371         af_alg_release_parent(sk);
 372 }
 373
 374 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
 375 {
 376         struct af_alg_ctx *ctx;
 377         struct alg_sock *ask = alg_sk(sk);
 378         struct crypto_skcipher *tfm = private;
 379         unsigned int len = sizeof(*ctx);
 380
 381         ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 382         if (!ctx)
 383                 return -ENOMEM;
 384         memset(ctx, 0, len);
 385
 386         ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
 387                                GFP_KERNEL);
 388         if (!ctx->iv) {
 389                 sock_kfree_s(sk, ctx, len);
 390                 return -ENOMEM;
 391         }
 392         memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
 393
 394         INIT_LIST_HEAD(&ctx->tsgl_list);
 395         ctx->len = len;
 396         crypto_init_wait(&ctx->wait);
 397
 398         ask->private = ctx;
 399
 400         sk->sk_destruct = skcipher_sock_destruct;
 401
 402         return 0;
 403 }
 404
 405 static int skcipher_accept_parent(void *private, struct sock *sk)
 406 {
 407         struct crypto_skcipher *tfm = private;
 408
 409         if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 410                 return -ENOKEY;
 411
 412         return skcipher_accept_parent_nokey(private, sk);
 413 }
 414
 415 static const struct af_alg_type algif_type_skcipher = {
 416         .bind           =       skcipher_bind,
 417         .release        =       skcipher_release,
 418         .setkey         =       skcipher_setkey,
 419         .accept         =       skcipher_accept_parent,
 420         .accept_nokey   =       skcipher_accept_parent_nokey,
 421         .ops            =       &algif_skcipher_ops,
 422         .ops_nokey      =       &algif_skcipher_ops_nokey,
 423         .name           =       "skcipher",
 424         .owner          =       THIS_MODULE
 425 };
 426
 427 static int __init algif_skcipher_init(void)
 428 {
 429         return af_alg_register_type(&algif_type_skcipher);
 430 }
 431
 432 static void __exit algif_skcipher_exit(void)
 433 {
 434         int err = af_alg_unregister_type(&algif_type_skcipher);
 435         BUG_ON(err);
 436 }
 437
 438 module_init(algif_skcipher_init);
 439 module_exit(algif_skcipher_exit);
 440 MODULE_DESCRIPTION("Userspace interface for skcipher algorithms");
 441 MODULE_LICENSE("GPL");