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 skcipher_sendmsg(struct socket * sock,struct msghdr * msg,size_t size)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 algif_skcipher_export(struct sock * sk,struct skcipher_request * req)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 algif_skcipher_done(void * data,int err)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 _skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)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 skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)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 skcipher_check_key(struct socket * sock)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 skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)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 skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)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 skcipher_bind(const char * name,u32 type,u32 mask)343 static void *skcipher_bind(const char *name, u32 type, u32 mask) 344 { 345 return crypto_alloc_skcipher(name, type, mask); 346 } 347 skcipher_release(void * private)348 static void skcipher_release(void *private) 349 { 350 crypto_free_skcipher(private); 351 } 352 skcipher_setkey(void * private,const u8 * key,unsigned int keylen)353 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) 354 { 355 return crypto_skcipher_setkey(private, key, keylen); 356 } 357 skcipher_sock_destruct(struct sock * sk)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 skcipher_accept_parent_nokey(void * private,struct sock * sk)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 skcipher_accept_parent(void * private,struct sock * sk)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 algif_skcipher_init(void)427 static int __init algif_skcipher_init(void) 428 { 429 return af_alg_register_type(&algif_type_skcipher); 430 } 431 algif_skcipher_exit(void)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"); 442