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
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
_skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)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
skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)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
skcipher_check_key(struct socket * sock)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
skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)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
skcipher_sendpage_nokey(struct socket * sock,struct page * page,int offset,size_t size,int flags)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
skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)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
skcipher_bind(const char * name,u32 type,u32 mask)304 static void *skcipher_bind(const char *name, u32 type, u32 mask)
305 {
306 return crypto_alloc_skcipher(name, type, mask);
307 }
308
skcipher_release(void * private)309 static void skcipher_release(void *private)
310 {
311 crypto_free_skcipher(private);
312 }
313
skcipher_setkey(void * private,const u8 * key,unsigned int keylen)314 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
315 {
316 return crypto_skcipher_setkey(private, key, keylen);
317 }
318
skcipher_sock_destruct(struct sock * sk)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
skcipher_accept_parent_nokey(void * private,struct sock * sk)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
skcipher_accept_parent(void * private,struct sock * sk)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
algif_skcipher_init(void)391 static int __init algif_skcipher_init(void)
392 {
393 return af_alg_register_type(&algif_type_skcipher);
394 }
395
algif_skcipher_exit(void)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");
405
