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 _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
143free:
144	af_alg_free_resources(areq);
145
146	return err ? err : len;
147}
148
149static 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
176out:
177	af_alg_wmem_wakeup(sk);
178	release_sock(sk);
179	return ret;
180}
181
182static 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
201static 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
228unlock:
229	release_sock(psk);
230unlock_child:
231	release_sock(sk);
232
233	return err;
234}
235
236static 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
248static 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
260static 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
279static void *skcipher_bind(const char *name, u32 type, u32 mask)
280{
281	return crypto_alloc_skcipher(name, type, mask);
282}
283
284static void skcipher_release(void *private)
285{
286	crypto_free_skcipher(private);
287}
288
289static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
290{
291	return crypto_skcipher_setkey(private, key, keylen);
292}
293
294static 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
308static 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
339static 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
349static 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
361static int __init algif_skcipher_init(void)
362{
363	return af_alg_register_type(&algif_type_skcipher);
364}
365
366static void __exit algif_skcipher_exit(void)
367{
368	int err = af_alg_unregister_type(&algif_type_skcipher);
369	BUG_ON(err);
370}
371
372module_init(algif_skcipher_init);
373module_exit(algif_skcipher_exit);
374MODULE_LICENSE("GPL");
375