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 sendmsg. Filling up the TX
13 * SGL does not cause a crypto operation -- the data will only be tracked by
14 * the kernel. Upon receipt of one recvmsg call, the caller must provide a
15 * 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.sgt.sgl, 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 .mmap = sock_no_mmap,
192 .bind = sock_no_bind,
193 .accept = sock_no_accept,
194
195 .release = af_alg_release,
196 .sendmsg = skcipher_sendmsg,
197 .recvmsg = skcipher_recvmsg,
198 .poll = af_alg_poll,
199 };
200
skcipher_check_key(struct socket * sock)201 static int skcipher_check_key(struct socket *sock)
202 {
203 int err = 0;
204 struct sock *psk;
205 struct alg_sock *pask;
206 struct crypto_skcipher *tfm;
207 struct sock *sk = sock->sk;
208 struct alg_sock *ask = alg_sk(sk);
209
210 lock_sock(sk);
211 if (!atomic_read(&ask->nokey_refcnt))
212 goto unlock_child;
213
214 psk = ask->parent;
215 pask = alg_sk(ask->parent);
216 tfm = pask->private;
217
218 err = -ENOKEY;
219 lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
220 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
221 goto unlock;
222
223 atomic_dec(&pask->nokey_refcnt);
224 atomic_set(&ask->nokey_refcnt, 0);
225
226 err = 0;
227
228 unlock:
229 release_sock(psk);
230 unlock_child:
231 release_sock(sk);
232
233 return err;
234 }
235
skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)236 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
237 size_t size)
238 {
239 int err;
240
241 err = skcipher_check_key(sock);
242 if (err)
243 return err;
244
245 return skcipher_sendmsg(sock, msg, size);
246 }
247
skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)248 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
249 size_t ignored, int flags)
250 {
251 int err;
252
253 err = skcipher_check_key(sock);
254 if (err)
255 return err;
256
257 return skcipher_recvmsg(sock, msg, ignored, flags);
258 }
259
260 static struct proto_ops algif_skcipher_ops_nokey = {
261 .family = PF_ALG,
262
263 .connect = sock_no_connect,
264 .socketpair = sock_no_socketpair,
265 .getname = sock_no_getname,
266 .ioctl = sock_no_ioctl,
267 .listen = sock_no_listen,
268 .shutdown = sock_no_shutdown,
269 .mmap = sock_no_mmap,
270 .bind = sock_no_bind,
271 .accept = sock_no_accept,
272
273 .release = af_alg_release,
274 .sendmsg = skcipher_sendmsg_nokey,
275 .recvmsg = skcipher_recvmsg_nokey,
276 .poll = af_alg_poll,
277 };
278
skcipher_bind(const char * name,u32 type,u32 mask)279 static void *skcipher_bind(const char *name, u32 type, u32 mask)
280 {
281 return crypto_alloc_skcipher(name, type, mask);
282 }
283
skcipher_release(void * private)284 static void skcipher_release(void *private)
285 {
286 crypto_free_skcipher(private);
287 }
288
skcipher_setkey(void * private,const u8 * key,unsigned int keylen)289 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
290 {
291 return crypto_skcipher_setkey(private, key, keylen);
292 }
293
skcipher_sock_destruct(struct sock * sk)294 static void skcipher_sock_destruct(struct sock *sk)
295 {
296 struct alg_sock *ask = alg_sk(sk);
297 struct af_alg_ctx *ctx = ask->private;
298 struct sock *psk = ask->parent;
299 struct alg_sock *pask = alg_sk(psk);
300 struct crypto_skcipher *tfm = pask->private;
301
302 af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
303 sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
304 sock_kfree_s(sk, ctx, ctx->len);
305 af_alg_release_parent(sk);
306 }
307
skcipher_accept_parent_nokey(void * private,struct sock * sk)308 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
309 {
310 struct af_alg_ctx *ctx;
311 struct alg_sock *ask = alg_sk(sk);
312 struct crypto_skcipher *tfm = private;
313 unsigned int len = sizeof(*ctx);
314
315 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
316 if (!ctx)
317 return -ENOMEM;
318 memset(ctx, 0, len);
319
320 ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
321 GFP_KERNEL);
322 if (!ctx->iv) {
323 sock_kfree_s(sk, ctx, len);
324 return -ENOMEM;
325 }
326 memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
327
328 INIT_LIST_HEAD(&ctx->tsgl_list);
329 ctx->len = len;
330 crypto_init_wait(&ctx->wait);
331
332 ask->private = ctx;
333
334 sk->sk_destruct = skcipher_sock_destruct;
335
336 return 0;
337 }
338
skcipher_accept_parent(void * private,struct sock * sk)339 static int skcipher_accept_parent(void *private, struct sock *sk)
340 {
341 struct crypto_skcipher *tfm = private;
342
343 if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
344 return -ENOKEY;
345
346 return skcipher_accept_parent_nokey(private, sk);
347 }
348
349 static const struct af_alg_type algif_type_skcipher = {
350 .bind = skcipher_bind,
351 .release = skcipher_release,
352 .setkey = skcipher_setkey,
353 .accept = skcipher_accept_parent,
354 .accept_nokey = skcipher_accept_parent_nokey,
355 .ops = &algif_skcipher_ops,
356 .ops_nokey = &algif_skcipher_ops_nokey,
357 .name = "skcipher",
358 .owner = THIS_MODULE
359 };
360
algif_skcipher_init(void)361 static int __init algif_skcipher_init(void)
362 {
363 return af_alg_register_type(&algif_type_skcipher);
364 }
365
algif_skcipher_exit(void)366 static void __exit algif_skcipher_exit(void)
367 {
368 int err = af_alg_unregister_type(&algif_type_skcipher);
369 BUG_ON(err);
370 }
371
372 module_init(algif_skcipher_init);
373 module_exit(algif_skcipher_exit);
374 MODULE_LICENSE("GPL");
375
