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, ctx->used, &len);
82 if (err)
83 goto free;
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)
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 (!atomic_read(&ask->nokey_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 atomic_dec(&pask->nokey_refcnt);
231 atomic_set(&ask->nokey_refcnt, 0);
232
233 err = 0;
234
235 unlock:
236 release_sock(psk);
237 unlock_child:
238 release_sock(sk);
239
240 return err;
241 }
242
skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)243 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
244 size_t size)
245 {
246 int err;
247
248 err = skcipher_check_key(sock);
249 if (err)
250 return err;
251
252 return skcipher_sendmsg(sock, msg, size);
253 }
254
skcipher_sendpage_nokey(struct socket * sock,struct page * page,int offset,size_t size,int flags)255 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
256 int offset, size_t size, int flags)
257 {
258 int err;
259
260 err = skcipher_check_key(sock);
261 if (err)
262 return err;
263
264 return af_alg_sendpage(sock, page, offset, size, flags);
265 }
266
skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)267 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
268 size_t ignored, int flags)
269 {
270 int err;
271
272 err = skcipher_check_key(sock);
273 if (err)
274 return err;
275
276 return skcipher_recvmsg(sock, msg, ignored, flags);
277 }
278
279 static struct proto_ops algif_skcipher_ops_nokey = {
280 .family = PF_ALG,
281
282 .connect = sock_no_connect,
283 .socketpair = sock_no_socketpair,
284 .getname = sock_no_getname,
285 .ioctl = sock_no_ioctl,
286 .listen = sock_no_listen,
287 .shutdown = sock_no_shutdown,
288 .getsockopt = sock_no_getsockopt,
289 .mmap = sock_no_mmap,
290 .bind = sock_no_bind,
291 .accept = sock_no_accept,
292 .setsockopt = sock_no_setsockopt,
293
294 .release = af_alg_release,
295 .sendmsg = skcipher_sendmsg_nokey,
296 .sendpage = skcipher_sendpage_nokey,
297 .recvmsg = skcipher_recvmsg_nokey,
298 .poll = af_alg_poll,
299 };
300
skcipher_bind(const char * name,u32 type,u32 mask)301 static void *skcipher_bind(const char *name, u32 type, u32 mask)
302 {
303 return crypto_alloc_skcipher(name, type, mask);
304 }
305
skcipher_release(void * private)306 static void skcipher_release(void *private)
307 {
308 crypto_free_skcipher(private);
309 }
310
skcipher_setkey(void * private,const u8 * key,unsigned int keylen)311 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
312 {
313 return crypto_skcipher_setkey(private, key, keylen);
314 }
315
skcipher_sock_destruct(struct sock * sk)316 static void skcipher_sock_destruct(struct sock *sk)
317 {
318 struct alg_sock *ask = alg_sk(sk);
319 struct af_alg_ctx *ctx = ask->private;
320 struct sock *psk = ask->parent;
321 struct alg_sock *pask = alg_sk(psk);
322 struct crypto_skcipher *tfm = pask->private;
323
324 af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
325 sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
326 sock_kfree_s(sk, ctx, ctx->len);
327 af_alg_release_parent(sk);
328 }
329
skcipher_accept_parent_nokey(void * private,struct sock * sk)330 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
331 {
332 struct af_alg_ctx *ctx;
333 struct alg_sock *ask = alg_sk(sk);
334 struct crypto_skcipher *tfm = private;
335 unsigned int len = sizeof(*ctx);
336
337 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
338 if (!ctx)
339 return -ENOMEM;
340
341 ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
342 GFP_KERNEL);
343 if (!ctx->iv) {
344 sock_kfree_s(sk, ctx, len);
345 return -ENOMEM;
346 }
347
348 memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
349
350 INIT_LIST_HEAD(&ctx->tsgl_list);
351 ctx->len = len;
352 ctx->used = 0;
353 atomic_set(&ctx->rcvused, 0);
354 ctx->more = 0;
355 ctx->merge = 0;
356 ctx->enc = 0;
357 crypto_init_wait(&ctx->wait);
358
359 ask->private = ctx;
360
361 sk->sk_destruct = skcipher_sock_destruct;
362
363 return 0;
364 }
365
skcipher_accept_parent(void * private,struct sock * sk)366 static int skcipher_accept_parent(void *private, struct sock *sk)
367 {
368 struct crypto_skcipher *tfm = private;
369
370 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
371 return -ENOKEY;
372
373 return skcipher_accept_parent_nokey(private, sk);
374 }
375
376 static const struct af_alg_type algif_type_skcipher = {
377 .bind = skcipher_bind,
378 .release = skcipher_release,
379 .setkey = skcipher_setkey,
380 .accept = skcipher_accept_parent,
381 .accept_nokey = skcipher_accept_parent_nokey,
382 .ops = &algif_skcipher_ops,
383 .ops_nokey = &algif_skcipher_ops_nokey,
384 .name = "skcipher",
385 .owner = THIS_MODULE
386 };
387
algif_skcipher_init(void)388 static int __init algif_skcipher_init(void)
389 {
390 return af_alg_register_type(&algif_type_skcipher);
391 }
392
algif_skcipher_exit(void)393 static void __exit algif_skcipher_exit(void)
394 {
395 int err = af_alg_unregister_type(&algif_type_skcipher);
396 BUG_ON(err);
397 }
398
399 module_init(algif_skcipher_init);
400 module_exit(algif_skcipher_exit);
401 MODULE_LICENSE("GPL");
402