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
37static 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
50static int algif_skcipher_export(struct sock *sk, struct skcipher_request *req)
51{
52	struct alg_sock *ask = alg_sk(sk);
53	struct crypto_skcipher *tfm;
54	struct af_alg_ctx *ctx;
55	struct alg_sock *pask;
56	unsigned statesize;
57	struct sock *psk;
58	int err;
59
60	if (!(req->base.flags & CRYPTO_SKCIPHER_REQ_NOTFINAL))
61		return 0;
62
63	ctx = ask->private;
64	psk = ask->parent;
65	pask = alg_sk(psk);
66	tfm = pask->private;
67
68	statesize = crypto_skcipher_statesize(tfm);
69	ctx->state = sock_kmalloc(sk, statesize, GFP_ATOMIC);
70	if (!ctx->state)
71		return -ENOMEM;
72
73	err = crypto_skcipher_export(req, ctx->state);
74	if (err) {
75		sock_kzfree_s(sk, ctx->state, statesize);
76		ctx->state = NULL;
77	}
78
79	return err;
80}
81
82static void algif_skcipher_done(void *data, int err)
83{
84	struct af_alg_async_req *areq = data;
85	struct sock *sk = areq->sk;
86
87	if (err)
88		goto out;
89
90	err = algif_skcipher_export(sk, &areq->cra_u.skcipher_req);
91
92out:
93	af_alg_async_cb(data, err);
94}
95
96static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
97			     size_t ignored, int flags)
98{
99	struct sock *sk = sock->sk;
100	struct alg_sock *ask = alg_sk(sk);
101	struct sock *psk = ask->parent;
102	struct alg_sock *pask = alg_sk(psk);
103	struct af_alg_ctx *ctx = ask->private;
104	struct crypto_skcipher *tfm = pask->private;
105	unsigned int bs = crypto_skcipher_chunksize(tfm);
106	struct af_alg_async_req *areq;
107	unsigned cflags = 0;
108	int err = 0;
109	size_t len = 0;
110
111	if (!ctx->init || (ctx->more && ctx->used < bs)) {
112		err = af_alg_wait_for_data(sk, flags, bs);
113		if (err)
114			return err;
115	}
116
117	/* Allocate cipher request for current operation. */
118	areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
119				     crypto_skcipher_reqsize(tfm));
120	if (IS_ERR(areq))
121		return PTR_ERR(areq);
122
123	/* convert iovecs of output buffers into RX SGL */
124	err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
125	if (err)
126		goto free;
127
128	/*
129	 * If more buffers are to be expected to be processed, process only
130	 * full block size buffers.
131	 */
132	if (ctx->more || len < ctx->used) {
133		len -= len % bs;
134		cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL;
135	}
136
137	/*
138	 * Create a per request TX SGL for this request which tracks the
139	 * SG entries from the global TX SGL.
140	 */
141	areq->tsgl_entries = af_alg_count_tsgl(sk, len, 0);
142	if (!areq->tsgl_entries)
143		areq->tsgl_entries = 1;
144	areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
145						 areq->tsgl_entries),
146				  GFP_KERNEL);
147	if (!areq->tsgl) {
148		err = -ENOMEM;
149		goto free;
150	}
151	sg_init_table(areq->tsgl, areq->tsgl_entries);
152	af_alg_pull_tsgl(sk, len, areq->tsgl, 0);
153
154	/* Initialize the crypto operation */
155	skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
156	skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
157				   areq->first_rsgl.sgl.sgt.sgl, len, ctx->iv);
158
159	if (ctx->state) {
160		err = crypto_skcipher_import(&areq->cra_u.skcipher_req,
161					     ctx->state);
162		sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
163		ctx->state = NULL;
164		if (err)
165			goto free;
166		cflags |= CRYPTO_SKCIPHER_REQ_CONT;
167	}
168
169	if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
170		/* AIO operation */
171		sock_hold(sk);
172		areq->iocb = msg->msg_iocb;
173
174		/* Remember output size that will be generated. */
175		areq->outlen = len;
176
177		skcipher_request_set_callback(&areq->cra_u.skcipher_req,
178					      cflags |
179					      CRYPTO_TFM_REQ_MAY_SLEEP,
180					      algif_skcipher_done, areq);
181		err = ctx->enc ?
182			crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
183			crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
184
185		/* AIO operation in progress */
186		if (err == -EINPROGRESS)
187			return -EIOCBQUEUED;
188
189		sock_put(sk);
190	} else {
191		/* Synchronous operation */
192		skcipher_request_set_callback(&areq->cra_u.skcipher_req,
193					      cflags |
194					      CRYPTO_TFM_REQ_MAY_SLEEP |
195					      CRYPTO_TFM_REQ_MAY_BACKLOG,
196					      crypto_req_done, &ctx->wait);
197		err = crypto_wait_req(ctx->enc ?
198			crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
199			crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
200						 &ctx->wait);
201
202		if (!err)
203			err = algif_skcipher_export(
204				sk, &areq->cra_u.skcipher_req);
205	}
206
207free:
208	af_alg_free_resources(areq);
209
210	return err ? err : len;
211}
212
213static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
214			    size_t ignored, int flags)
215{
216	struct sock *sk = sock->sk;
217	int ret = 0;
218
219	lock_sock(sk);
220	while (msg_data_left(msg)) {
221		int err = _skcipher_recvmsg(sock, msg, ignored, flags);
222
223		/*
224		 * This error covers -EIOCBQUEUED which implies that we can
225		 * only handle one AIO request. If the caller wants to have
226		 * multiple AIO requests in parallel, he must make multiple
227		 * separate AIO calls.
228		 *
229		 * Also return the error if no data has been processed so far.
230		 */
231		if (err <= 0) {
232			if (err == -EIOCBQUEUED || !ret)
233				ret = err;
234			goto out;
235		}
236
237		ret += err;
238	}
239
240out:
241	af_alg_wmem_wakeup(sk);
242	release_sock(sk);
243	return ret;
244}
245
246static struct proto_ops algif_skcipher_ops = {
247	.family		=	PF_ALG,
248
249	.connect	=	sock_no_connect,
250	.socketpair	=	sock_no_socketpair,
251	.getname	=	sock_no_getname,
252	.ioctl		=	sock_no_ioctl,
253	.listen		=	sock_no_listen,
254	.shutdown	=	sock_no_shutdown,
255	.mmap		=	sock_no_mmap,
256	.bind		=	sock_no_bind,
257	.accept		=	sock_no_accept,
258
259	.release	=	af_alg_release,
260	.sendmsg	=	skcipher_sendmsg,
261	.recvmsg	=	skcipher_recvmsg,
262	.poll		=	af_alg_poll,
263};
264
265static int skcipher_check_key(struct socket *sock)
266{
267	int err = 0;
268	struct sock *psk;
269	struct alg_sock *pask;
270	struct crypto_skcipher *tfm;
271	struct sock *sk = sock->sk;
272	struct alg_sock *ask = alg_sk(sk);
273
274	lock_sock(sk);
275	if (!atomic_read(&ask->nokey_refcnt))
276		goto unlock_child;
277
278	psk = ask->parent;
279	pask = alg_sk(ask->parent);
280	tfm = pask->private;
281
282	err = -ENOKEY;
283	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
284	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
285		goto unlock;
286
287	atomic_dec(&pask->nokey_refcnt);
288	atomic_set(&ask->nokey_refcnt, 0);
289
290	err = 0;
291
292unlock:
293	release_sock(psk);
294unlock_child:
295	release_sock(sk);
296
297	return err;
298}
299
300static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
301				  size_t size)
302{
303	int err;
304
305	err = skcipher_check_key(sock);
306	if (err)
307		return err;
308
309	return skcipher_sendmsg(sock, msg, size);
310}
311
312static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
313				  size_t ignored, int flags)
314{
315	int err;
316
317	err = skcipher_check_key(sock);
318	if (err)
319		return err;
320
321	return skcipher_recvmsg(sock, msg, ignored, flags);
322}
323
324static struct proto_ops algif_skcipher_ops_nokey = {
325	.family		=	PF_ALG,
326
327	.connect	=	sock_no_connect,
328	.socketpair	=	sock_no_socketpair,
329	.getname	=	sock_no_getname,
330	.ioctl		=	sock_no_ioctl,
331	.listen		=	sock_no_listen,
332	.shutdown	=	sock_no_shutdown,
333	.mmap		=	sock_no_mmap,
334	.bind		=	sock_no_bind,
335	.accept		=	sock_no_accept,
336
337	.release	=	af_alg_release,
338	.sendmsg	=	skcipher_sendmsg_nokey,
339	.recvmsg	=	skcipher_recvmsg_nokey,
340	.poll		=	af_alg_poll,
341};
342
343static void *skcipher_bind(const char *name, u32 type, u32 mask)
344{
345	return crypto_alloc_skcipher(name, type, mask);
346}
347
348static void skcipher_release(void *private)
349{
350	crypto_free_skcipher(private);
351}
352
353static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
354{
355	return crypto_skcipher_setkey(private, key, keylen);
356}
357
358static void skcipher_sock_destruct(struct sock *sk)
359{
360	struct alg_sock *ask = alg_sk(sk);
361	struct af_alg_ctx *ctx = ask->private;
362	struct sock *psk = ask->parent;
363	struct alg_sock *pask = alg_sk(psk);
364	struct crypto_skcipher *tfm = pask->private;
365
366	af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
367	sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
368	if (ctx->state)
369		sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
370	sock_kfree_s(sk, ctx, ctx->len);
371	af_alg_release_parent(sk);
372}
373
374static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
375{
376	struct af_alg_ctx *ctx;
377	struct alg_sock *ask = alg_sk(sk);
378	struct crypto_skcipher *tfm = private;
379	unsigned int len = sizeof(*ctx);
380
381	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
382	if (!ctx)
383		return -ENOMEM;
384	memset(ctx, 0, len);
385
386	ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
387			       GFP_KERNEL);
388	if (!ctx->iv) {
389		sock_kfree_s(sk, ctx, len);
390		return -ENOMEM;
391	}
392	memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
393
394	INIT_LIST_HEAD(&ctx->tsgl_list);
395	ctx->len = len;
396	crypto_init_wait(&ctx->wait);
397
398	ask->private = ctx;
399
400	sk->sk_destruct = skcipher_sock_destruct;
401
402	return 0;
403}
404
405static int skcipher_accept_parent(void *private, struct sock *sk)
406{
407	struct crypto_skcipher *tfm = private;
408
409	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
410		return -ENOKEY;
411
412	return skcipher_accept_parent_nokey(private, sk);
413}
414
415static const struct af_alg_type algif_type_skcipher = {
416	.bind		=	skcipher_bind,
417	.release	=	skcipher_release,
418	.setkey		=	skcipher_setkey,
419	.accept		=	skcipher_accept_parent,
420	.accept_nokey	=	skcipher_accept_parent_nokey,
421	.ops		=	&algif_skcipher_ops,
422	.ops_nokey	=	&algif_skcipher_ops_nokey,
423	.name		=	"skcipher",
424	.owner		=	THIS_MODULE
425};
426
427static int __init algif_skcipher_init(void)
428{
429	return af_alg_register_type(&algif_type_skcipher);
430}
431
432static void __exit algif_skcipher_exit(void)
433{
434	int err = af_alg_unregister_type(&algif_type_skcipher);
435	BUG_ON(err);
436}
437
438module_init(algif_skcipher_init);
439module_exit(algif_skcipher_exit);
440MODULE_LICENSE("GPL");
441