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_chunksize(tfm);
60 struct af_alg_async_req *areq;
61 int err = 0;
62 size_t len = 0;
63
64 if (!ctx->init || (ctx->more && ctx->used < bs)) {
65 err = af_alg_wait_for_data(sk, flags, bs);
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, ctx->used, &len);
78 if (err)
79 goto free;
80
81 /*
82 * If more buffers are to be expected to be processed, process only
83 * full block size buffers.
84 */
85 if (ctx->more || len < ctx->used)
86 len -= len % bs;
87
88 /*
89 * Create a per request TX SGL for this request which tracks the
90 * SG entries from the global TX SGL.
91 */
92 areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
93 if (!areq->tsgl_entries)
94 areq->tsgl_entries = 1;
95 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
96 areq->tsgl_entries),
97 GFP_KERNEL);
98 if (!areq->tsgl) {
99 err = -ENOMEM;
100 goto free;
101 }
102 sg_init_table(areq->tsgl, areq->tsgl_entries);
103 af_alg_pull_tsgl(sk, len, areq->tsgl, 0);
104
105 /* Initialize the crypto operation */
106 skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
107 skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
108 areq->first_rsgl.sgl.sg, len, ctx->iv);
109
110 if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
111 /* AIO operation */
112 sock_hold(sk);
113 areq->iocb = msg->msg_iocb;
114
115 /* Remember output size that will be generated. */
116 areq->outlen = len;
117
118 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
119 CRYPTO_TFM_REQ_MAY_SLEEP,
120 af_alg_async_cb, areq);
121 err = ctx->enc ?
122 crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
123 crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
124
125 /* AIO operation in progress */
126 if (err == -EINPROGRESS)
127 return -EIOCBQUEUED;
128
129 sock_put(sk);
130 } else {
131 /* Synchronous operation */
132 skcipher_request_set_callback(&areq->cra_u.skcipher_req,
133 CRYPTO_TFM_REQ_MAY_SLEEP |
134 CRYPTO_TFM_REQ_MAY_BACKLOG,
135 crypto_req_done, &ctx->wait);
136 err = crypto_wait_req(ctx->enc ?
137 crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
138 crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
139 &ctx->wait);
140 }
141
142
143 free:
144 af_alg_free_resources(areq);
145
146 return err ? err : len;
147 }
148
skcipher_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)149 static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
150 size_t ignored, int flags)
151 {
152 struct sock *sk = sock->sk;
153 int ret = 0;
154
155 lock_sock(sk);
156 while (msg_data_left(msg)) {
157 int err = _skcipher_recvmsg(sock, msg, ignored, flags);
158
159 /*
160 * This error covers -EIOCBQUEUED which implies that we can
161 * only handle one AIO request. If the caller wants to have
162 * multiple AIO requests in parallel, he must make multiple
163 * separate AIO calls.
164 *
165 * Also return the error if no data has been processed so far.
166 */
167 if (err <= 0) {
168 if (err == -EIOCBQUEUED || !ret)
169 ret = err;
170 goto out;
171 }
172
173 ret += err;
174 }
175
176 out:
177 af_alg_wmem_wakeup(sk);
178 release_sock(sk);
179 return ret;
180 }
181
182 static struct proto_ops algif_skcipher_ops = {
183 .family = PF_ALG,
184
185 .connect = sock_no_connect,
186 .socketpair = sock_no_socketpair,
187 .getname = sock_no_getname,
188 .ioctl = sock_no_ioctl,
189 .listen = sock_no_listen,
190 .shutdown = sock_no_shutdown,
191 .getsockopt = sock_no_getsockopt,
192 .mmap = sock_no_mmap,
193 .bind = sock_no_bind,
194 .accept = sock_no_accept,
195 .setsockopt = sock_no_setsockopt,
196
197 .release = af_alg_release,
198 .sendmsg = skcipher_sendmsg,
199 .sendpage = af_alg_sendpage,
200 .recvmsg = skcipher_recvmsg,
201 .poll = af_alg_poll,
202 };
203
skcipher_check_key(struct socket * sock)204 static int skcipher_check_key(struct socket *sock)
205 {
206 int err = 0;
207 struct sock *psk;
208 struct alg_sock *pask;
209 struct crypto_skcipher *tfm;
210 struct sock *sk = sock->sk;
211 struct alg_sock *ask = alg_sk(sk);
212
213 lock_sock(sk);
214 if (!atomic_read(&ask->nokey_refcnt))
215 goto unlock_child;
216
217 psk = ask->parent;
218 pask = alg_sk(ask->parent);
219 tfm = pask->private;
220
221 err = -ENOKEY;
222 lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
223 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
224 goto unlock;
225
226 atomic_dec(&pask->nokey_refcnt);
227 atomic_set(&ask->nokey_refcnt, 0);
228
229 err = 0;
230
231 unlock:
232 release_sock(psk);
233 unlock_child:
234 release_sock(sk);
235
236 return err;
237 }
238
skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)239 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
240 size_t size)
241 {
242 int err;
243
244 err = skcipher_check_key(sock);
245 if (err)
246 return err;
247
248 return skcipher_sendmsg(sock, msg, size);
249 }
250
skcipher_sendpage_nokey(struct socket * sock,struct page * page,int offset,size_t size,int flags)251 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
252 int offset, size_t size, int flags)
253 {
254 int err;
255
256 err = skcipher_check_key(sock);
257 if (err)
258 return err;
259
260 return af_alg_sendpage(sock, page, offset, size, flags);
261 }
262
skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)263 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
264 size_t ignored, int flags)
265 {
266 int err;
267
268 err = skcipher_check_key(sock);
269 if (err)
270 return err;
271
272 return skcipher_recvmsg(sock, msg, ignored, flags);
273 }
274
275 static struct proto_ops algif_skcipher_ops_nokey = {
276 .family = PF_ALG,
277
278 .connect = sock_no_connect,
279 .socketpair = sock_no_socketpair,
280 .getname = sock_no_getname,
281 .ioctl = sock_no_ioctl,
282 .listen = sock_no_listen,
283 .shutdown = sock_no_shutdown,
284 .getsockopt = sock_no_getsockopt,
285 .mmap = sock_no_mmap,
286 .bind = sock_no_bind,
287 .accept = sock_no_accept,
288 .setsockopt = sock_no_setsockopt,
289
290 .release = af_alg_release,
291 .sendmsg = skcipher_sendmsg_nokey,
292 .sendpage = skcipher_sendpage_nokey,
293 .recvmsg = skcipher_recvmsg_nokey,
294 .poll = af_alg_poll,
295 };
296
skcipher_bind(const char * name,u32 type,u32 mask)297 static void *skcipher_bind(const char *name, u32 type, u32 mask)
298 {
299 return crypto_alloc_skcipher(name, type, mask);
300 }
301
skcipher_release(void * private)302 static void skcipher_release(void *private)
303 {
304 crypto_free_skcipher(private);
305 }
306
skcipher_setkey(void * private,const u8 * key,unsigned int keylen)307 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
308 {
309 return crypto_skcipher_setkey(private, key, keylen);
310 }
311
skcipher_sock_destruct(struct sock * sk)312 static void skcipher_sock_destruct(struct sock *sk)
313 {
314 struct alg_sock *ask = alg_sk(sk);
315 struct af_alg_ctx *ctx = ask->private;
316 struct sock *psk = ask->parent;
317 struct alg_sock *pask = alg_sk(psk);
318 struct crypto_skcipher *tfm = pask->private;
319
320 af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
321 sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
322 sock_kfree_s(sk, ctx, ctx->len);
323 af_alg_release_parent(sk);
324 }
325
skcipher_accept_parent_nokey(void * private,struct sock * sk)326 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
327 {
328 struct af_alg_ctx *ctx;
329 struct alg_sock *ask = alg_sk(sk);
330 struct crypto_skcipher *tfm = private;
331 unsigned int len = sizeof(*ctx);
332
333 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
334 if (!ctx)
335 return -ENOMEM;
336 memset(ctx, 0, len);
337
338 ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
339 GFP_KERNEL);
340 if (!ctx->iv) {
341 sock_kfree_s(sk, ctx, len);
342 return -ENOMEM;
343 }
344 memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
345
346 INIT_LIST_HEAD(&ctx->tsgl_list);
347 ctx->len = len;
348 crypto_init_wait(&ctx->wait);
349
350 ask->private = ctx;
351
352 sk->sk_destruct = skcipher_sock_destruct;
353
354 return 0;
355 }
356
skcipher_accept_parent(void * private,struct sock * sk)357 static int skcipher_accept_parent(void *private, struct sock *sk)
358 {
359 struct crypto_skcipher *tfm = private;
360
361 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
362 return -ENOKEY;
363
364 return skcipher_accept_parent_nokey(private, sk);
365 }
366
367 static const struct af_alg_type algif_type_skcipher = {
368 .bind = skcipher_bind,
369 .release = skcipher_release,
370 .setkey = skcipher_setkey,
371 .accept = skcipher_accept_parent,
372 .accept_nokey = skcipher_accept_parent_nokey,
373 .ops = &algif_skcipher_ops,
374 .ops_nokey = &algif_skcipher_ops_nokey,
375 .name = "skcipher",
376 .owner = THIS_MODULE
377 };
378
algif_skcipher_init(void)379 static int __init algif_skcipher_init(void)
380 {
381 return af_alg_register_type(&algif_type_skcipher);
382 }
383
algif_skcipher_exit(void)384 static void __exit algif_skcipher_exit(void)
385 {
386 int err = af_alg_unregister_type(&algif_type_skcipher);
387 BUG_ON(err);
388 }
389
390 module_init(algif_skcipher_init);
391 module_exit(algif_skcipher_exit);
392 MODULE_LICENSE("GPL");
393