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 sendpage/sendmsg. Filling
  13  * up the TX SGL does not cause a crypto operation -- the data will only be
  14  * tracked by the kernel. Upon receipt of one recvmsg call, the caller must
  15  * provide a 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 _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
  51                              size_t ignored, int flags)
  52 {
  53         struct sock *sk = sock->sk;
  54         struct alg_sock *ask = alg_sk(sk);
  55         struct sock *psk = ask->parent;
  56         struct alg_sock *pask = alg_sk(psk);
  57         struct af_alg_ctx *ctx = ask->private;
  58         struct crypto_skcipher *tfm = pask->private;
  59         unsigned int bs = crypto_skcipher_chunksize(tfm);
  60         struct af_alg_async_req *areq;
  61         int err = 0;
  62         size_t len = 0;
  63
  64         if (!ctx->used) {
  65                 err = af_alg_wait_for_data(sk, flags);
  66                 if (err)
  67                         return err;
  68         }
  69
  70         /* Allocate cipher request for current operation. */
  71         areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
  72                                      crypto_skcipher_reqsize(tfm));
  73         if (IS_ERR(areq))
  74                 return PTR_ERR(areq);
  75
  76         /* convert iovecs of output buffers into RX SGL */
  77         err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
  78         if (err)
  79                 goto free;
  80
  81         /* Process only as much RX buffers for which we have TX data */
  82         if (len > ctx->used)
  83                 len = ctx->used;
  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 (ask->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         if (!pask->refcnt++)
 231                 sock_hold(psk);
 232
 233         ask->refcnt = 1;
 234         sock_put(psk);
 235
 236         err = 0;
 237
 238 unlock:
 239         release_sock(psk);
 240 unlock_child:
 241         release_sock(sk);
 242
 243         return err;
 244 }
 245
 246 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
 247                                   size_t size)
 248 {
 249         int err;
 250
 251         err = skcipher_check_key(sock);
 252         if (err)
 253                 return err;
 254
 255         return skcipher_sendmsg(sock, msg, size);
 256 }
 257
 258 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
 259                                        int offset, size_t size, int flags)
 260 {
 261         int err;
 262
 263         err = skcipher_check_key(sock);
 264         if (err)
 265                 return err;
 266
 267         return af_alg_sendpage(sock, page, offset, size, flags);
 268 }
 269
 270 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
 271                                   size_t ignored, int flags)
 272 {
 273         int err;
 274
 275         err = skcipher_check_key(sock);
 276         if (err)
 277                 return err;
 278
 279         return skcipher_recvmsg(sock, msg, ignored, flags);
 280 }
 281
 282 static struct proto_ops algif_skcipher_ops_nokey = {
 283         .family         =       PF_ALG,
 284
 285         .connect        =       sock_no_connect,
 286         .socketpair     =       sock_no_socketpair,
 287         .getname        =       sock_no_getname,
 288         .ioctl          =       sock_no_ioctl,
 289         .listen         =       sock_no_listen,
 290         .shutdown       =       sock_no_shutdown,
 291         .getsockopt     =       sock_no_getsockopt,
 292         .mmap           =       sock_no_mmap,
 293         .bind           =       sock_no_bind,
 294         .accept         =       sock_no_accept,
 295         .setsockopt     =       sock_no_setsockopt,
 296
 297         .release        =       af_alg_release,
 298         .sendmsg        =       skcipher_sendmsg_nokey,
 299         .sendpage       =       skcipher_sendpage_nokey,
 300         .recvmsg        =       skcipher_recvmsg_nokey,
 301         .poll           =       af_alg_poll,
 302 };
 303
 304 static void *skcipher_bind(const char *name, u32 type, u32 mask)
 305 {
 306         return crypto_alloc_skcipher(name, type, mask);
 307 }
 308
 309 static void skcipher_release(void *private)
 310 {
 311         crypto_free_skcipher(private);
 312 }
 313
 314 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
 315 {
 316         return crypto_skcipher_setkey(private, key, keylen);
 317 }
 318
 319 static void skcipher_sock_destruct(struct sock *sk)
 320 {
 321         struct alg_sock *ask = alg_sk(sk);
 322         struct af_alg_ctx *ctx = ask->private;
 323         struct sock *psk = ask->parent;
 324         struct alg_sock *pask = alg_sk(psk);
 325         struct crypto_skcipher *tfm = pask->private;
 326
 327         af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
 328         sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
 329         sock_kfree_s(sk, ctx, ctx->len);
 330         af_alg_release_parent(sk);
 331 }
 332
 333 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
 334 {
 335         struct af_alg_ctx *ctx;
 336         struct alg_sock *ask = alg_sk(sk);
 337         struct crypto_skcipher *tfm = private;
 338         unsigned int len = sizeof(*ctx);
 339
 340         ctx = sock_kmalloc(sk, len, GFP_KERNEL);
 341         if (!ctx)
 342                 return -ENOMEM;
 343
 344         ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
 345                                GFP_KERNEL);
 346         if (!ctx->iv) {
 347                 sock_kfree_s(sk, ctx, len);
 348                 return -ENOMEM;
 349         }
 350
 351         memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
 352
 353         INIT_LIST_HEAD(&ctx->tsgl_list);
 354         ctx->len = len;
 355         ctx->used = 0;
 356         atomic_set(&ctx->rcvused, 0);
 357         ctx->more = 0;
 358         ctx->merge = 0;
 359         ctx->enc = 0;
 360         crypto_init_wait(&ctx->wait);
 361
 362         ask->private = ctx;
 363
 364         sk->sk_destruct = skcipher_sock_destruct;
 365
 366         return 0;
 367 }
 368
 369 static int skcipher_accept_parent(void *private, struct sock *sk)
 370 {
 371         struct crypto_skcipher *tfm = private;
 372
 373         if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
 374                 return -ENOKEY;
 375
 376         return skcipher_accept_parent_nokey(private, sk);
 377 }
 378
 379 static const struct af_alg_type algif_type_skcipher = {
 380         .bind           =       skcipher_bind,
 381         .release        =       skcipher_release,
 382         .setkey         =       skcipher_setkey,
 383         .accept         =       skcipher_accept_parent,
 384         .accept_nokey   =       skcipher_accept_parent_nokey,
 385         .ops            =       &algif_skcipher_ops,
 386         .ops_nokey      =       &algif_skcipher_ops_nokey,
 387         .name           =       "skcipher",
 388         .owner          =       THIS_MODULE
 389 };
 390
 391 static int __init algif_skcipher_init(void)
 392 {
 393         return af_alg_register_type(&algif_type_skcipher);
 394 }
 395
 396 static void __exit algif_skcipher_exit(void)
 397 {
 398         int err = af_alg_unregister_type(&algif_type_skcipher);
 399         BUG_ON(err);
 400 }
 401
 402 module_init(algif_skcipher_init);
 403 module_exit(algif_skcipher_exit);
 404 MODULE_LICENSE("GPL");