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 const struct af_alg_allowlist_entry skcipher_allowlist[] = { 38 { "adiantum(xchacha12,aes)", false }, /* cryptsetup */ 39 { "adiantum(xchacha20,aes)", false }, /* cryptsetup */ 40 { "cbc(aes)", true }, /* iwd */ 41 { "cbc(des)", true }, /* iwd */ 42 { "cbc(des3_ede)", true }, /* iwd */ 43 { "ctr(aes)", true }, /* iwd */ 44 { "ecb(aes)", true }, /* iwd, bluez */ 45 { "ecb(des)", true }, /* iwd */ 46 { "hctr2(aes)", false }, /* cryptsetup */ 47 { "xts(aes)", false }, /* cryptsetup benchmark */ 48 { "xts(camellia)", false }, /* cryptsetup */ 49 { "xts(serpent)", false }, /* cryptsetup */ 50 { "xts(twofish)", false }, /* cryptsetup */ 51 {}, 52 }; 53 54 static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg, 55 size_t size) 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 crypto_skcipher *tfm = pask->private; 62 unsigned ivsize = crypto_skcipher_ivsize(tfm); 63 64 return af_alg_sendmsg(sock, msg, size, ivsize); 65 } 66 67 static int algif_skcipher_export(struct sock *sk, struct skcipher_request *req) 68 { 69 struct alg_sock *ask = alg_sk(sk); 70 struct crypto_skcipher *tfm; 71 struct af_alg_ctx *ctx; 72 struct alg_sock *pask; 73 unsigned statesize; 74 struct sock *psk; 75 int err; 76 77 if (!(req->base.flags & CRYPTO_SKCIPHER_REQ_NOTFINAL)) 78 return 0; 79 80 ctx = ask->private; 81 psk = ask->parent; 82 pask = alg_sk(psk); 83 tfm = pask->private; 84 85 statesize = crypto_skcipher_statesize(tfm); 86 ctx->state = sock_kmalloc(sk, statesize, GFP_ATOMIC); 87 if (!ctx->state) 88 return -ENOMEM; 89 90 err = crypto_skcipher_export(req, ctx->state); 91 if (err) { 92 sock_kzfree_s(sk, ctx->state, statesize); 93 ctx->state = NULL; 94 } 95 96 return err; 97 } 98 99 static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg, 100 size_t ignored, int flags) 101 { 102 struct sock *sk = sock->sk; 103 struct alg_sock *ask = alg_sk(sk); 104 struct sock *psk = ask->parent; 105 struct alg_sock *pask = alg_sk(psk); 106 struct af_alg_ctx *ctx = ask->private; 107 struct crypto_skcipher *tfm = pask->private; 108 unsigned int bs = crypto_skcipher_chunksize(tfm); 109 struct af_alg_async_req *areq; 110 unsigned cflags = 0; 111 int err = 0; 112 size_t len = 0; 113 114 if (!ctx->init || (ctx->more && ctx->used < bs)) { 115 err = af_alg_wait_for_data(sk, flags, bs); 116 if (err) 117 return err; 118 } 119 120 /* Allocate cipher request for current operation. */ 121 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) + 122 crypto_skcipher_reqsize(tfm)); 123 if (IS_ERR(areq)) 124 return PTR_ERR(areq); 125 126 /* convert iovecs of output buffers into RX SGL */ 127 err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len); 128 if (err) 129 goto free; 130 131 /* 132 * If more buffers are to be expected to be processed, process only 133 * full block size buffers. 134 */ 135 if (ctx->more || len < ctx->used) { 136 if (len < bs) { 137 err = -EINVAL; 138 goto free; 139 } 140 141 len -= len % bs; 142 cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL; 143 } 144 145 /* 146 * Create a per request TX SGL for this request which tracks the 147 * SG entries from the global TX SGL. 148 */ 149 areq->tsgl_entries = af_alg_count_tsgl(sk, len); 150 if (!areq->tsgl_entries) 151 areq->tsgl_entries = 1; 152 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl), 153 areq->tsgl_entries), 154 GFP_KERNEL); 155 if (!areq->tsgl) { 156 err = -ENOMEM; 157 goto free; 158 } 159 sg_init_table(areq->tsgl, areq->tsgl_entries); 160 af_alg_pull_tsgl(sk, len, areq->tsgl); 161 162 /* Initialize the crypto operation */ 163 skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm); 164 skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl, 165 areq->first_rsgl.sgl.sgt.sgl, len, ctx->iv); 166 167 if (ctx->state) { 168 err = crypto_skcipher_import(&areq->cra_u.skcipher_req, 169 ctx->state); 170 sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm)); 171 ctx->state = NULL; 172 if (err) 173 goto free; 174 cflags |= CRYPTO_SKCIPHER_REQ_CONT; 175 } 176 177 skcipher_request_set_callback(&areq->cra_u.skcipher_req, 178 cflags | 179 CRYPTO_TFM_REQ_MAY_SLEEP | 180 CRYPTO_TFM_REQ_MAY_BACKLOG, 181 crypto_req_done, &ctx->wait); 182 err = crypto_wait_req(ctx->enc ? 183 crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) : 184 crypto_skcipher_decrypt(&areq->cra_u.skcipher_req), 185 &ctx->wait); 186 187 if (!err) 188 err = algif_skcipher_export( 189 sk, &areq->cra_u.skcipher_req); 190 191 free: 192 af_alg_free_resources(areq); 193 194 return err ? err : len; 195 } 196 197 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg, 198 size_t ignored, int flags) 199 { 200 struct sock *sk = sock->sk; 201 int ret = 0; 202 203 lock_sock(sk); 204 while (msg_data_left(msg)) { 205 int err = _skcipher_recvmsg(sock, msg, ignored, flags); 206 207 /* 208 * This error covers -EIOCBQUEUED which implies that we can 209 * only handle one AIO request. If the caller wants to have 210 * multiple AIO requests in parallel, he must make multiple 211 * separate AIO calls. 212 * 213 * Also return the error if no data has been processed so far. 214 */ 215 if (err <= 0) { 216 if (err == -EIOCBQUEUED || !ret) 217 ret = err; 218 goto out; 219 } 220 221 ret += err; 222 } 223 224 out: 225 af_alg_wmem_wakeup(sk); 226 release_sock(sk); 227 return ret; 228 } 229 230 static struct proto_ops algif_skcipher_ops = { 231 .family = PF_ALG, 232 233 .connect = sock_no_connect, 234 .socketpair = sock_no_socketpair, 235 .getname = sock_no_getname, 236 .ioctl = sock_no_ioctl, 237 .listen = sock_no_listen, 238 .shutdown = sock_no_shutdown, 239 .mmap = sock_no_mmap, 240 .bind = sock_no_bind, 241 .accept = sock_no_accept, 242 243 .release = af_alg_release, 244 .sendmsg = skcipher_sendmsg, 245 .recvmsg = skcipher_recvmsg, 246 .poll = af_alg_poll, 247 }; 248 249 static int skcipher_check_key(struct socket *sock) 250 { 251 int err = 0; 252 struct sock *psk; 253 struct alg_sock *pask; 254 struct crypto_skcipher *tfm; 255 struct sock *sk = sock->sk; 256 struct alg_sock *ask = alg_sk(sk); 257 258 lock_sock(sk); 259 if (!atomic_read(&ask->nokey_refcnt)) 260 goto unlock_child; 261 262 psk = ask->parent; 263 pask = alg_sk(ask->parent); 264 tfm = pask->private; 265 266 err = -ENOKEY; 267 lock_sock_nested(psk, SINGLE_DEPTH_NESTING); 268 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY) 269 goto unlock; 270 271 atomic_dec(&pask->nokey_refcnt); 272 atomic_set(&ask->nokey_refcnt, 0); 273 274 err = 0; 275 276 unlock: 277 release_sock(psk); 278 unlock_child: 279 release_sock(sk); 280 281 return err; 282 } 283 284 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg, 285 size_t size) 286 { 287 int err; 288 289 err = skcipher_check_key(sock); 290 if (err) 291 return err; 292 293 return skcipher_sendmsg(sock, msg, size); 294 } 295 296 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg, 297 size_t ignored, int flags) 298 { 299 int err; 300 301 err = skcipher_check_key(sock); 302 if (err) 303 return err; 304 305 return skcipher_recvmsg(sock, msg, ignored, flags); 306 } 307 308 static struct proto_ops algif_skcipher_ops_nokey = { 309 .family = PF_ALG, 310 311 .connect = sock_no_connect, 312 .socketpair = sock_no_socketpair, 313 .getname = sock_no_getname, 314 .ioctl = sock_no_ioctl, 315 .listen = sock_no_listen, 316 .shutdown = sock_no_shutdown, 317 .mmap = sock_no_mmap, 318 .bind = sock_no_bind, 319 .accept = sock_no_accept, 320 321 .release = af_alg_release, 322 .sendmsg = skcipher_sendmsg_nokey, 323 .recvmsg = skcipher_recvmsg_nokey, 324 .poll = af_alg_poll, 325 }; 326 327 static void *skcipher_bind(const char *name) 328 { 329 int err; 330 331 err = af_alg_check_restriction(name, skcipher_allowlist); 332 if (err) 333 return ERR_PTR(err); 334 335 return crypto_alloc_skcipher(name, 0, AF_ALG_CRYPTOAPI_MASK); 336 } 337 338 static void skcipher_release(void *private) 339 { 340 crypto_free_skcipher(private); 341 } 342 343 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) 344 { 345 return crypto_skcipher_setkey(private, key, keylen); 346 } 347 348 static void skcipher_sock_destruct(struct sock *sk) 349 { 350 struct alg_sock *ask = alg_sk(sk); 351 struct af_alg_ctx *ctx = ask->private; 352 struct sock *psk = ask->parent; 353 struct alg_sock *pask = alg_sk(psk); 354 struct crypto_skcipher *tfm = pask->private; 355 356 af_alg_pull_tsgl(sk, ctx->used, NULL); 357 sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm)); 358 if (ctx->state) 359 sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm)); 360 sock_kfree_s(sk, ctx, ctx->len); 361 af_alg_release_parent(sk); 362 } 363 364 static int skcipher_accept_parent_nokey(void *private, struct sock *sk) 365 { 366 struct af_alg_ctx *ctx; 367 struct alg_sock *ask = alg_sk(sk); 368 struct crypto_skcipher *tfm = private; 369 unsigned int len = sizeof(*ctx); 370 371 ctx = sock_kmalloc(sk, len, GFP_KERNEL); 372 if (!ctx) 373 return -ENOMEM; 374 memset(ctx, 0, len); 375 376 ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm), 377 GFP_KERNEL); 378 if (!ctx->iv) { 379 sock_kfree_s(sk, ctx, len); 380 return -ENOMEM; 381 } 382 memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm)); 383 384 INIT_LIST_HEAD(&ctx->tsgl_list); 385 ctx->len = len; 386 crypto_init_wait(&ctx->wait); 387 388 ask->private = ctx; 389 390 sk->sk_destruct = skcipher_sock_destruct; 391 392 return 0; 393 } 394 395 static int skcipher_accept_parent(void *private, struct sock *sk) 396 { 397 struct crypto_skcipher *tfm = private; 398 399 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY) 400 return -ENOKEY; 401 402 return skcipher_accept_parent_nokey(private, sk); 403 } 404 405 static const struct af_alg_type algif_type_skcipher = { 406 .bind = skcipher_bind, 407 .release = skcipher_release, 408 .setkey = skcipher_setkey, 409 .accept = skcipher_accept_parent, 410 .accept_nokey = skcipher_accept_parent_nokey, 411 .ops = &algif_skcipher_ops, 412 .ops_nokey = &algif_skcipher_ops_nokey, 413 .name = "skcipher", 414 .owner = THIS_MODULE 415 }; 416 417 static int __init algif_skcipher_init(void) 418 { 419 return af_alg_register_type(&algif_type_skcipher); 420 } 421 422 static void __exit algif_skcipher_exit(void) 423 { 424 int err = af_alg_unregister_type(&algif_type_skcipher); 425 BUG_ON(err); 426 } 427 428 module_init(algif_skcipher_init); 429 module_exit(algif_skcipher_exit); 430 MODULE_DESCRIPTION("Userspace interface for skcipher algorithms"); 431 MODULE_LICENSE("GPL"); 432