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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_blocksize(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"); |