algif_skcipher.c

  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		if (len < bs) {
134			err = -EINVAL;
135			goto free;
136		}
137
138		len -= len % bs;
139		cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL;
140	}
141
142	/*
143	 * Create a per request TX SGL for this request which tracks the
144	 * SG entries from the global TX SGL.
145	 */
146	areq->tsgl_entries = af_alg_count_tsgl(sk, len);
147	if (!areq->tsgl_entries)
148		areq->tsgl_entries = 1;
149	areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
150						 areq->tsgl_entries),
151				  GFP_KERNEL);
152	if (!areq->tsgl) {
153		err = -ENOMEM;
154		goto free;
155	}
156	sg_init_table(areq->tsgl, areq->tsgl_entries);
157	af_alg_pull_tsgl(sk, len, areq->tsgl);
158
159	/* Initialize the crypto operation */
160	skcipher_request_set_tfm(&areq->cra_u.skcipher_req, tfm);
161	skcipher_request_set_crypt(&areq->cra_u.skcipher_req, areq->tsgl,
162				   areq->first_rsgl.sgl.sgt.sgl, len, ctx->iv);
163
164	if (ctx->state) {
165		err = crypto_skcipher_import(&areq->cra_u.skcipher_req,
166					     ctx->state);
167		sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
168		ctx->state = NULL;
169		if (err)
170			goto free;
171		cflags |= CRYPTO_SKCIPHER_REQ_CONT;
172	}
173
174	if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
175		/* AIO operation */
176		sock_hold(sk);
177		areq->iocb = msg->msg_iocb;
178
179		/* Remember output size that will be generated. */
180		areq->outlen = len;
181
182		skcipher_request_set_callback(&areq->cra_u.skcipher_req,
183					      cflags |
184					      CRYPTO_TFM_REQ_MAY_SLEEP,
185					      algif_skcipher_done, areq);
186		err = ctx->enc ?
187			crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
188			crypto_skcipher_decrypt(&areq->cra_u.skcipher_req);
189
190		/* AIO operation in progress */
191		if (err == -EINPROGRESS)
192			return -EIOCBQUEUED;
193
194		sock_put(sk);
195	} else {
196		/* Synchronous operation */
197		skcipher_request_set_callback(&areq->cra_u.skcipher_req,
198					      cflags |
199					      CRYPTO_TFM_REQ_MAY_SLEEP |
200					      CRYPTO_TFM_REQ_MAY_BACKLOG,
201					      crypto_req_done, &ctx->wait);
202		err = crypto_wait_req(ctx->enc ?
203			crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) :
204			crypto_skcipher_decrypt(&areq->cra_u.skcipher_req),
205						 &ctx->wait);
206
207		if (!err)
208			err = algif_skcipher_export(
209				sk, &areq->cra_u.skcipher_req);
210	}
211
212free:
213	af_alg_free_resources(areq);
214
215	return err ? err : len;
216}
217
218static int skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
219			    size_t ignored, int flags)
220{
221	struct sock *sk = sock->sk;
222	int ret = 0;
223
224	lock_sock(sk);
225	while (msg_data_left(msg)) {
226		int err = _skcipher_recvmsg(sock, msg, ignored, flags);
227
228		/*
229		 * This error covers -EIOCBQUEUED which implies that we can
230		 * only handle one AIO request. If the caller wants to have
231		 * multiple AIO requests in parallel, he must make multiple
232		 * separate AIO calls.
233		 *
234		 * Also return the error if no data has been processed so far.
235		 */
236		if (err <= 0) {
237			if (err == -EIOCBQUEUED || !ret)
238				ret = err;
239			goto out;
240		}
241
242		ret += err;
243	}
244
245out:
246	af_alg_wmem_wakeup(sk);
247	release_sock(sk);
248	return ret;
249}
250
251static struct proto_ops algif_skcipher_ops = {
252	.family		=	PF_ALG,
253
254	.connect	=	sock_no_connect,
255	.socketpair	=	sock_no_socketpair,
256	.getname	=	sock_no_getname,
257	.ioctl		=	sock_no_ioctl,
258	.listen		=	sock_no_listen,
259	.shutdown	=	sock_no_shutdown,
260	.mmap		=	sock_no_mmap,
261	.bind		=	sock_no_bind,
262	.accept		=	sock_no_accept,
263
264	.release	=	af_alg_release,
265	.sendmsg	=	skcipher_sendmsg,
266	.recvmsg	=	skcipher_recvmsg,
267	.poll		=	af_alg_poll,
268};
269
270static int skcipher_check_key(struct socket *sock)
271{
272	int err = 0;
273	struct sock *psk;
274	struct alg_sock *pask;
275	struct crypto_skcipher *tfm;
276	struct sock *sk = sock->sk;
277	struct alg_sock *ask = alg_sk(sk);
278
279	lock_sock(sk);
280	if (!atomic_read(&ask->nokey_refcnt))
281		goto unlock_child;
282
283	psk = ask->parent;
284	pask = alg_sk(ask->parent);
285	tfm = pask->private;
286
287	err = -ENOKEY;
288	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
289	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
290		goto unlock;
291
292	atomic_dec(&pask->nokey_refcnt);
293	atomic_set(&ask->nokey_refcnt, 0);
294
295	err = 0;
296
297unlock:
298	release_sock(psk);
299unlock_child:
300	release_sock(sk);
301
302	return err;
303}
304
305static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
306				  size_t size)
307{
308	int err;
309
310	err = skcipher_check_key(sock);
311	if (err)
312		return err;
313
314	return skcipher_sendmsg(sock, msg, size);
315}
316
317static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
318				  size_t ignored, int flags)
319{
320	int err;
321
322	err = skcipher_check_key(sock);
323	if (err)
324		return err;
325
326	return skcipher_recvmsg(sock, msg, ignored, flags);
327}
328
329static struct proto_ops algif_skcipher_ops_nokey = {
330	.family		=	PF_ALG,
331
332	.connect	=	sock_no_connect,
333	.socketpair	=	sock_no_socketpair,
334	.getname	=	sock_no_getname,
335	.ioctl		=	sock_no_ioctl,
336	.listen		=	sock_no_listen,
337	.shutdown	=	sock_no_shutdown,
338	.mmap		=	sock_no_mmap,
339	.bind		=	sock_no_bind,
340	.accept		=	sock_no_accept,
341
342	.release	=	af_alg_release,
343	.sendmsg	=	skcipher_sendmsg_nokey,
344	.recvmsg	=	skcipher_recvmsg_nokey,
345	.poll		=	af_alg_poll,
346};
347
348static void *skcipher_bind(const char *name, u32 type, u32 mask)
349{
350	return crypto_alloc_skcipher(name, type, mask);
351}
352
353static void skcipher_release(void *private)
354{
355	crypto_free_skcipher(private);
356}
357
358static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
359{
360	return crypto_skcipher_setkey(private, key, keylen);
361}
362
363static void skcipher_sock_destruct(struct sock *sk)
364{
365	struct alg_sock *ask = alg_sk(sk);
366	struct af_alg_ctx *ctx = ask->private;
367	struct sock *psk = ask->parent;
368	struct alg_sock *pask = alg_sk(psk);
369	struct crypto_skcipher *tfm = pask->private;
370
371	af_alg_pull_tsgl(sk, ctx->used, NULL);
372	sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
373	if (ctx->state)
374		sock_kzfree_s(sk, ctx->state, crypto_skcipher_statesize(tfm));
375	sock_kfree_s(sk, ctx, ctx->len);
376	af_alg_release_parent(sk);
377}
378
379static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
380{
381	struct af_alg_ctx *ctx;
382	struct alg_sock *ask = alg_sk(sk);
383	struct crypto_skcipher *tfm = private;
384	unsigned int len = sizeof(*ctx);
385
386	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
387	if (!ctx)
388		return -ENOMEM;
389	memset(ctx, 0, len);
390
391	ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
392			       GFP_KERNEL);
393	if (!ctx->iv) {
394		sock_kfree_s(sk, ctx, len);
395		return -ENOMEM;
396	}
397	memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
398
399	INIT_LIST_HEAD(&ctx->tsgl_list);
400	ctx->len = len;
401	crypto_init_wait(&ctx->wait);
402
403	ask->private = ctx;
404
405	sk->sk_destruct = skcipher_sock_destruct;
406
407	return 0;
408}
409
410static int skcipher_accept_parent(void *private, struct sock *sk)
411{
412	struct crypto_skcipher *tfm = private;
413
414	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
415		return -ENOKEY;
416
417	return skcipher_accept_parent_nokey(private, sk);
418}
419
420static const struct af_alg_type algif_type_skcipher = {
421	.bind		=	skcipher_bind,
422	.release	=	skcipher_release,
423	.setkey		=	skcipher_setkey,
424	.accept		=	skcipher_accept_parent,
425	.accept_nokey	=	skcipher_accept_parent_nokey,
426	.ops		=	&algif_skcipher_ops,
427	.ops_nokey	=	&algif_skcipher_ops_nokey,
428	.name		=	"skcipher",
429	.owner		=	THIS_MODULE
430};
431
432static int __init algif_skcipher_init(void)
433{
434	return af_alg_register_type(&algif_type_skcipher);
435}
436
437static void __exit algif_skcipher_exit(void)
438{
439	int err = af_alg_unregister_type(&algif_type_skcipher);
440	BUG_ON(err);
441}
442
443module_init(algif_skcipher_init);
444module_exit(algif_skcipher_exit);
445MODULE_DESCRIPTION("Userspace interface for skcipher algorithms");
446MODULE_LICENSE("GPL");