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 int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, 83 size_t ignored, int flags) 84 { 85 struct sock *sk = sock->sk; 86 struct alg_sock *ask = alg_sk(sk); 87 struct sock *psk = ask->parent; 88 struct alg_sock *pask = alg_sk(psk); 89 struct af_alg_ctx *ctx = ask->private; 90 struct crypto_skcipher *tfm = pask->private; 91 unsigned int bs = crypto_skcipher_chunksize(tfm); 92 struct af_alg_async_req *areq; 93 unsigned cflags = 0; 94 int err = 0; 95 size_t len = 0; 96 97 if (!ctx->init || (ctx->more && ctx->used < bs)) { 98 err = af_alg_wait_for_data(sk, flags, bs); 99 if (err) 100 return err; 101 } 102 103 /* Allocate cipher request for current operation. */ 104 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + 105 crypto_skcipher_reqsize(tfm)); 106 if (IS_ERR(areq)) 107 return PTR_ERR(areq); 108 109 /* convert iovecs of output buffers into RX SGL */ 110 err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len); 111 if (err) 112 goto free; 113 114 /* 115 * If more buffers are to be expected to be processed, process only 116 * full block size buffers. 117 */ 118 if (ctx->more || len < ctx->used) { 119 if (len < bs) { 120 err = -EINVAL; 121 goto free; 122 } 123 124 len -= len % bs; 125 cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL; 126 } 127 128 /* 129 * Create a per request TX SGL for this request which tracks the 130 * SG entries from the global TX SGL. 131 */ 132 areq->tsgl_entries = af_alg_count_tsgl(sk, len); 133 if (!areq->tsgl_entries) 134 areq->tsgl_entries = 1; 135 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl), 136 areq->tsgl_entries), 137 GFP_KERNEL); 138 if (!areq->tsgl) { 139 err = -ENOMEM; 140 goto free; 141 } 142 sg_init_table(areq->tsgl, areq->tsgl_entries); 143 af_alg_pull_tsgl(sk, len, areq->tsgl); 144 145 /* Initialize the crypto operation */ 146 skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm); 147 skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl, 148 areq->first_rsgl.sgl.sgt.sgl, len, ctx->iv); 149 150 if (ctx->state) { 151 err = crypto_skcipher_import(&areq->cra_u.skcipher_req, 152 ctx->state); 153 sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm)); 154 ctx->state = NULL; 155 if (err) 156 goto free; 157 cflags |= CRYPTO_SKCIPHER_REQ_CONT; 158 } 159 160 skcipher_request_set_callback(&areq->cra_u.skcipher_req, 161 cflags | 162 CRYPTO_TFM_REQ_MAY_SLEEP | 163 CRYPTO_TFM_REQ_MAY_BACKLOG, 164 crypto_req_done, &ctx->wait); 165 err = crypto_wait_req(ctx->enc ? 166 crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) : 167 crypto_skcipher_decrypt(&areq->cra_u.skcipher_req), 168 &ctx->wait); 169 170 if (!err) 171 err = algif_skcipher_export( 172 sk, &areq->cra_u.skcipher_req); 173 174 free: 175 af_alg_free_resources(areq); 176 177 return err ? err : len; 178 } 179 180 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg, 181 size_t ignored, int flags) 182 { 183 struct sock *sk = sock->sk; 184 int ret = 0; 185 186 lock_sock(sk); 187 while (msg_data_left(msg)) { 188 int err = _skcipher_recvmsg(sock, msg, ignored, flags); 189 190 /* 191 * This error covers -EIOCBQUEUED which implies that we can 192 * only handle one AIO request. If the caller wants to have 193 * multiple AIO requests in parallel, he must make multiple 194 * separate AIO calls. 195 * 196 * Also return the error if no data has been processed so far. 197 */ 198 if (err <= 0) { 199 if (err == -EIOCBQUEUED || !ret) 200 ret = err; 201 goto out; 202 } 203 204 ret += err; 205 } 206 207 out: 208 af_alg_wmem_wakeup(sk); 209 release_sock(sk); 210 return ret; 211 } 212 213 static struct proto_ops algif_skcipher_ops = { 214 .family = PF_ALG, 215 216 .connect = sock_no_connect, 217 .socketpair = sock_no_socketpair, 218 .getname = sock_no_getname, 219 .ioctl = sock_no_ioctl, 220 .listen = sock_no_listen, 221 .shutdown = sock_no_shutdown, 222 .mmap = sock_no_mmap, 223 .bind = sock_no_bind, 224 .accept = sock_no_accept, 225 226 .release = af_alg_release, 227 .sendmsg = skcipher_sendmsg, 228 .recvmsg = skcipher_recvmsg, 229 .poll = af_alg_poll, 230 }; 231 232 static int skcipher_check_key(struct socket *sock) 233 { 234 int err = 0; 235 struct sock *psk; 236 struct alg_sock *pask; 237 struct crypto_skcipher *tfm; 238 struct sock *sk = sock->sk; 239 struct alg_sock *ask = alg_sk(sk); 240 241 lock_sock(sk); 242 if (!atomic_read(&ask->nokey_refcnt)) 243 goto unlock_child; 244 245 psk = ask->parent; 246 pask = alg_sk(ask->parent); 247 tfm = pask->private; 248 249 err = -ENOKEY; 250 lock_sock_nested(psk, SINGLE_DEPTH_NESTING); 251 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY) 252 goto unlock; 253 254 atomic_dec(&pask->nokey_refcnt); 255 atomic_set(&ask->nokey_refcnt, 0); 256 257 err = 0; 258 259 unlock: 260 release_sock(psk); 261 unlock_child: 262 release_sock(sk); 263 264 return err; 265 } 266 267 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg, 268 size_t size) 269 { 270 int err; 271 272 err = skcipher_check_key(sock); 273 if (err) 274 return err; 275 276 return skcipher_sendmsg(sock, msg, size); 277 } 278 279 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg, 280 size_t ignored, int flags) 281 { 282 int err; 283 284 err = skcipher_check_key(sock); 285 if (err) 286 return err; 287 288 return skcipher_recvmsg(sock, msg, ignored, flags); 289 } 290 291 static struct proto_ops algif_skcipher_ops_nokey = { 292 .family = PF_ALG, 293 294 .connect = sock_no_connect, 295 .socketpair = sock_no_socketpair, 296 .getname = sock_no_getname, 297 .ioctl = sock_no_ioctl, 298 .listen = sock_no_listen, 299 .shutdown = sock_no_shutdown, 300 .mmap = sock_no_mmap, 301 .bind = sock_no_bind, 302 .accept = sock_no_accept, 303 304 .release = af_alg_release, 305 .sendmsg = skcipher_sendmsg_nokey, 306 .recvmsg = skcipher_recvmsg_nokey, 307 .poll = af_alg_poll, 308 }; 309 310 static void *skcipher_bind(const char *name) 311 { 312 return crypto_alloc_skcipher(name, 0, AF_ALG_CRYPTOAPI_MASK); 313 } 314 315 static void skcipher_release(void *private) 316 { 317 crypto_free_skcipher(private); 318 } 319 320 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) 321 { 322 return crypto_skcipher_setkey(private, key, keylen); 323 } 324 325 static void skcipher_sock_destruct(struct sock *sk) 326 { 327 struct alg_sock *ask = alg_sk(sk); 328 struct af_alg_ctx *ctx = ask->private; 329 struct sock *psk = ask->parent; 330 struct alg_sock *pask = alg_sk(psk); 331 struct crypto_skcipher *tfm = pask->private; 332 333 af_alg_pull_tsgl(sk, ctx->used, NULL); 334 sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm)); 335 if (ctx->state) 336 sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm)); 337 sock_kfree_s(sk, ctx, ctx->len); 338 af_alg_release_parent(sk); 339 } 340 341 static int skcipher_accept_parent_nokey(void *private, struct sock *sk) 342 { 343 struct af_alg_ctx *ctx; 344 struct alg_sock *ask = alg_sk(sk); 345 struct crypto_skcipher *tfm = private; 346 unsigned int len = sizeof(*ctx); 347 348 ctx = sock_kmalloc(sk, len, GFP_KERNEL); 349 if (!ctx) 350 return -ENOMEM; 351 memset(ctx, 0, len); 352 353 ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm), 354 GFP_KERNEL); 355 if (!ctx->iv) { 356 sock_kfree_s(sk, ctx, len); 357 return -ENOMEM; 358 } 359 memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm)); 360 361 INIT_LIST_HEAD(&ctx->tsgl_list); 362 ctx->len = len; 363 crypto_init_wait(&ctx->wait); 364 365 ask->private = ctx; 366 367 sk->sk_destruct = skcipher_sock_destruct; 368 369 return 0; 370 } 371 372 static int skcipher_accept_parent(void *private, struct sock *sk) 373 { 374 struct crypto_skcipher *tfm = private; 375 376 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY) 377 return -ENOKEY; 378 379 return skcipher_accept_parent_nokey(private, sk); 380 } 381 382 static const struct af_alg_type algif_type_skcipher = { 383 .bind = skcipher_bind, 384 .release = skcipher_release, 385 .setkey = skcipher_setkey, 386 .accept = skcipher_accept_parent, 387 .accept_nokey = skcipher_accept_parent_nokey, 388 .ops = &algif_skcipher_ops, 389 .ops_nokey = &algif_skcipher_ops_nokey, 390 .name = "skcipher", 391 .owner = THIS_MODULE 392 }; 393 394 static int __init algif_skcipher_init(void) 395 { 396 return af_alg_register_type(&algif_type_skcipher); 397 } 398 399 static void __exit algif_skcipher_exit(void) 400 { 401 int err = af_alg_unregister_type(&algif_type_skcipher); 402 BUG_ON(err); 403 } 404 405 module_init(algif_skcipher_init); 406 module_exit(algif_skcipher_exit); 407 MODULE_DESCRIPTION("Userspace interface for skcipher algorithms"); 408 MODULE_LICENSE("GPL"); 409