1 /*
2 * algif_skcipher: User-space interface for skcipher algorithms
3 *
4 * This file provides the user-space API for symmetric key ciphers.
5 *
6 * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 *
13 * The following concept of the memory management is used:
14 *
15 * The kernel maintains two SGLs, the TX SGL and the RX SGL. The TX SGL is
16 * filled by user space with the data submitted via sendpage/sendmsg. Filling
17 * up the TX SGL does not cause a crypto operation -- the data will only be
18 * tracked by the kernel. Upon receipt of one recvmsg call, the caller must
19 * provide a buffer which is tracked with the RX SGL.
20 *
21 * During the processing of the recvmsg operation, the cipher request is
22 * allocated and prepared. As part of the recvmsg operation, the processed
23 * TX buffers are extracted from the TX SGL into a separate SGL.
24 *
25 * After the completion of the crypto operation, the RX SGL and the cipher
26 * request is released. The extracted TX SGL parts are released together with
27 * the RX SGL release.
28 */
29
30 #include <crypto/scatterwalk.h>
31 #include <crypto/skcipher.h>
32 #include <crypto/if_alg.h>
33 #include <linux/init.h>
34 #include <linux/list.h>
35 #include <linux/kernel.h>
36 #include <linux/mm.h>
37 #include <linux/module.h>
38 #include <linux/net.h>
39 #include <net/sock.h>
40
skcipher_sendmsg(struct socket * sock,struct msghdr * msg,size_t size)41 static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
42 size_t size)
43 {
44 struct sock *sk = sock->sk;
45 struct alg_sock *ask = alg_sk(sk);
46 struct sock *psk = ask->parent;
47 struct alg_sock *pask = alg_sk(psk);
48 struct crypto_skcipher *tfm = pask->private;
49 unsigned ivsize = crypto_skcipher_ivsize(tfm);
50
51 return af_alg_sendmsg(sock, msg, size, ivsize);
52 }
53
_skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)54 static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
55 size_t ignored, int flags)
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 af_alg_ctx *ctx = ask->private;
62 struct crypto_skcipher *tfm = pask->private;
63 unsigned int bs = crypto_skcipher_blocksize(tfm);
64 struct af_alg_async_req *areq;
65 int err = 0;
66 size_t len = 0;
67
68 if (!ctx->used) {
69 err = af_alg_wait_for_data(sk, flags);
70 if (err)
71 return err;
72 }
73
74 /* Allocate cipher request for current operation. */
75 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
76 crypto_skcipher_reqsize(tfm));
77 if (IS_ERR(areq))
78 return PTR_ERR(areq);
79
80 /* convert iovecs of output buffers into RX SGL */
81 err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
82 if (err)
83 goto free;
84
85 /* Process only as much RX buffers for which we have TX data */
86 if (len > ctx->used)
87 len = ctx->used;
88
89 /*
90 * If more buffers are to be expected to be processed, process only
91 * full block size buffers.
92 */
93 if (ctx->more || len < ctx->used)
94 len -= len % bs;
95
96 /*
97 * Create a per request TX SGL for this request which tracks the
98 * SG entries from the global TX SGL.
99 */
100 areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
101 if (!areq->tsgl_entries)
102 areq->tsgl_entries = 1;
103 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
104 areq->tsgl_entries),
105 GFP_KERNEL);
106 if (!areq->tsgl) {
107 err = -ENOMEM;
108 goto free;
109 }
110 sg_init_table(areq->tsgl, areq->tsgl_entries);
111 af_alg_pull_tsgl(sk, len, areq->tsgl, 0);
112
113 /* Initialize the crypto operation */
114 skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
115 skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
116 areq->first_rsgl.sgl.sg, len, ctx->iv);
117
118 if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
119 /* AIO operation */
120 sock_hold(sk);
121 areq->iocb = msg->msg_iocb;
122
123 /* Remember output size that will be generated. */
124 areq->outlen = len;
125
126 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
127 CRYPTO_TFM_REQ_MAY_SLEEP,
128 af_alg_async_cb, areq);
129 err = ctx->enc ?
130 crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
131 crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
132
133 /* AIO operation in progress */
134 if (err == -EINPROGRESS || err == -EBUSY)
135 return -EIOCBQUEUED;
136
137 sock_put(sk);
138 } else {
139 /* Synchronous operation */
140 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
141 CRYPTO_TFM_REQ_MAY_SLEEP |
142 CRYPTO_TFM_REQ_MAY_BACKLOG,
143 crypto_req_done, &ctx->wait);
144 err = crypto_wait_req(ctx->enc ?
145 crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
146 crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
147 &ctx->wait);
148 }
149
150
151 free:
152 af_alg_free_resources(areq);
153
154 return err ? err : len;
155 }
156
skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)157 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
158 size_t ignored, int flags)
159 {
160 struct sock *sk = sock->sk;
161 int ret = 0;
162
163 lock_sock(sk);
164 while (msg_data_left(msg)) {
165 int err = _skcipher_recvmsg(sock, msg, ignored, flags);
166
167 /*
168 * This error covers -EIOCBQUEUED which implies that we can
169 * only handle one AIO request. If the caller wants to have
170 * multiple AIO requests in parallel, he must make multiple
171 * separate AIO calls.
172 *
173 * Also return the error if no data has been processed so far.
174 */
175 if (err <= 0) {
176 if (err == -EIOCBQUEUED || !ret)
177 ret = err;
178 goto out;
179 }
180
181 ret += err;
182 }
183
184 out:
185 af_alg_wmem_wakeup(sk);
186 release_sock(sk);
187 return ret;
188 }
189
190 static struct proto_ops algif_skcipher_ops = {
191 .family = PF_ALG,
192
193 .connect = sock_no_connect,
194 .socketpair = sock_no_socketpair,
195 .getname = sock_no_getname,
196 .ioctl = sock_no_ioctl,
197 .listen = sock_no_listen,
198 .shutdown = sock_no_shutdown,
199 .getsockopt = sock_no_getsockopt,
200 .mmap = sock_no_mmap,
201 .bind = sock_no_bind,
202 .accept = sock_no_accept,
203 .setsockopt = sock_no_setsockopt,
204
205 .release = af_alg_release,
206 .sendmsg = skcipher_sendmsg,
207 .sendpage = af_alg_sendpage,
208 .recvmsg = skcipher_recvmsg,
209 .poll = af_alg_poll,
210 };
211
skcipher_check_key(struct socket * sock)212 static int skcipher_check_key(struct socket *sock)
213 {
214 int err = 0;
215 struct sock *psk;
216 struct alg_sock *pask;
217 struct crypto_skcipher *tfm;
218 struct sock *sk = sock->sk;
219 struct alg_sock *ask = alg_sk(sk);
220
221 lock_sock(sk);
222 if (ask->refcnt)
223 goto unlock_child;
224
225 psk = ask->parent;
226 pask = alg_sk(ask->parent);
227 tfm = pask->private;
228
229 err = -ENOKEY;
230 lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
231 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
232 goto unlock;
233
234 if (!pask->refcnt++)
235 sock_hold(psk);
236
237 ask->refcnt = 1;
238 sock_put(psk);
239
240 err = 0;
241
242 unlock:
243 release_sock(psk);
244 unlock_child:
245 release_sock(sk);
246
247 return err;
248 }
249
skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)250 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
251 size_t size)
252 {
253 int err;
254
255 err = skcipher_check_key(sock);
256 if (err)
257 return err;
258
259 return skcipher_sendmsg(sock, msg, size);
260 }
261
skcipher_sendpage_nokey(struct socket * sock,struct page * page,int offset,size_t size,int flags)262 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
263 int offset, size_t size, int flags)
264 {
265 int err;
266
267 err = skcipher_check_key(sock);
268 if (err)
269 return err;
270
271 return af_alg_sendpage(sock, page, offset, size, flags);
272 }
273
skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)274 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
275 size_t ignored, int flags)
276 {
277 int err;
278
279 err = skcipher_check_key(sock);
280 if (err)
281 return err;
282
283 return skcipher_recvmsg(sock, msg, ignored, flags);
284 }
285
286 static struct proto_ops algif_skcipher_ops_nokey = {
287 .family = PF_ALG,
288
289 .connect = sock_no_connect,
290 .socketpair = sock_no_socketpair,
291 .getname = sock_no_getname,
292 .ioctl = sock_no_ioctl,
293 .listen = sock_no_listen,
294 .shutdown = sock_no_shutdown,
295 .getsockopt = sock_no_getsockopt,
296 .mmap = sock_no_mmap,
297 .bind = sock_no_bind,
298 .accept = sock_no_accept,
299 .setsockopt = sock_no_setsockopt,
300
301 .release = af_alg_release,
302 .sendmsg = skcipher_sendmsg_nokey,
303 .sendpage = skcipher_sendpage_nokey,
304 .recvmsg = skcipher_recvmsg_nokey,
305 .poll = af_alg_poll,
306 };
307
skcipher_bind(const char * name,u32 type,u32 mask)308 static void *skcipher_bind(const char *name, u32 type, u32 mask)
309 {
310 return crypto_alloc_skcipher(name, type, mask);
311 }
312
skcipher_release(void * private)313 static void skcipher_release(void *private)
314 {
315 crypto_free_skcipher(private);
316 }
317
skcipher_setkey(void * private,const u8 * key,unsigned int keylen)318 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
319 {
320 return crypto_skcipher_setkey(private, key, keylen);
321 }
322
skcipher_sock_destruct(struct sock * sk)323 static void skcipher_sock_destruct(struct sock *sk)
324 {
325 struct alg_sock *ask = alg_sk(sk);
326 struct af_alg_ctx *ctx = ask->private;
327 struct sock *psk = ask->parent;
328 struct alg_sock *pask = alg_sk(psk);
329 struct crypto_skcipher *tfm = pask->private;
330
331 af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
332 sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
333 sock_kfree_s(sk, ctx, ctx->len);
334 af_alg_release_parent(sk);
335 }
336
skcipher_accept_parent_nokey(void * private,struct sock * sk)337 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
338 {
339 struct af_alg_ctx *ctx;
340 struct alg_sock *ask = alg_sk(sk);
341 struct crypto_skcipher *tfm = private;
342 unsigned int len = sizeof(*ctx);
343
344 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
345 if (!ctx)
346 return -ENOMEM;
347
348 ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
349 GFP_KERNEL);
350 if (!ctx->iv) {
351 sock_kfree_s(sk, ctx, len);
352 return -ENOMEM;
353 }
354
355 memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
356
357 INIT_LIST_HEAD(&ctx->tsgl_list);
358 ctx->len = len;
359 ctx->used = 0;
360 atomic_set(&ctx->rcvused, 0);
361 ctx->more = 0;
362 ctx->merge = 0;
363 ctx->enc = 0;
364 crypto_init_wait(&ctx->wait);
365
366 ask->private = ctx;
367
368 sk->sk_destruct = skcipher_sock_destruct;
369
370 return 0;
371 }
372
skcipher_accept_parent(void * private,struct sock * sk)373 static int skcipher_accept_parent(void *private, struct sock *sk)
374 {
375 struct crypto_skcipher *tfm = private;
376
377 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
378 return -ENOKEY;
379
380 return skcipher_accept_parent_nokey(private, sk);
381 }
382
383 static const struct af_alg_type algif_type_skcipher = {
384 .bind = skcipher_bind,
385 .release = skcipher_release,
386 .setkey = skcipher_setkey,
387 .accept = skcipher_accept_parent,
388 .accept_nokey = skcipher_accept_parent_nokey,
389 .ops = &algif_skcipher_ops,
390 .ops_nokey = &algif_skcipher_ops_nokey,
391 .name = "skcipher",
392 .owner = THIS_MODULE
393 };
394
algif_skcipher_init(void)395 static int __init algif_skcipher_init(void)
396 {
397 return af_alg_register_type(&algif_type_skcipher);
398 }
399
algif_skcipher_exit(void)400 static void __exit algif_skcipher_exit(void)
401 {
402 int err = af_alg_unregister_type(&algif_type_skcipher);
403 BUG_ON(err);
404 }
405
406 module_init(algif_skcipher_init);
407 module_exit(algif_skcipher_exit);
408 MODULE_LICENSE("GPL");
409
