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 	.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 	.sendpage	=	af_alg_sendpage,
198 	.recvmsg	=	skcipher_recvmsg,
199 	.poll		=	af_alg_poll,
200 };
201 
skcipher_check_key(struct socket * sock)202 static int skcipher_check_key(struct socket *sock)
203 {
204 	int err = 0;
205 	struct sock *psk;
206 	struct alg_sock *pask;
207 	struct crypto_skcipher *tfm;
208 	struct sock *sk = sock->sk;
209 	struct alg_sock *ask = alg_sk(sk);
210 
211 	lock_sock(sk);
212 	if (!atomic_read(&ask->nokey_refcnt))
213 		goto unlock_child;
214 
215 	psk = ask->parent;
216 	pask = alg_sk(ask->parent);
217 	tfm = pask->private;
218 
219 	err = -ENOKEY;
220 	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
221 	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
222 		goto unlock;
223 
224 	atomic_dec(&pask->nokey_refcnt);
225 	atomic_set(&ask->nokey_refcnt, 0);
226 
227 	err = 0;
228 
229 unlock:
230 	release_sock(psk);
231 unlock_child:
232 	release_sock(sk);
233 
234 	return err;
235 }
236 
skcipher_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)237 static int skcipher_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
238 				  size_t size)
239 {
240 	int err;
241 
242 	err = skcipher_check_key(sock);
243 	if (err)
244 		return err;
245 
246 	return skcipher_sendmsg(sock, msg, size);
247 }
248 
skcipher_sendpage_nokey(struct socket * sock,struct page * page,int offset,size_t size,int flags)249 static ssize_t skcipher_sendpage_nokey(struct socket *sock, struct page *page,
250 				       int offset, size_t size, int flags)
251 {
252 	int err;
253 
254 	err = skcipher_check_key(sock);
255 	if (err)
256 		return err;
257 
258 	return af_alg_sendpage(sock, page, offset, size, flags);
259 }
260 
skcipher_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)261 static int skcipher_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
262 				  size_t ignored, int flags)
263 {
264 	int err;
265 
266 	err = skcipher_check_key(sock);
267 	if (err)
268 		return err;
269 
270 	return skcipher_recvmsg(sock, msg, ignored, flags);
271 }
272 
273 static struct proto_ops algif_skcipher_ops_nokey = {
274 	.family		=	PF_ALG,
275 
276 	.connect	=	sock_no_connect,
277 	.socketpair	=	sock_no_socketpair,
278 	.getname	=	sock_no_getname,
279 	.ioctl		=	sock_no_ioctl,
280 	.listen		=	sock_no_listen,
281 	.shutdown	=	sock_no_shutdown,
282 	.mmap		=	sock_no_mmap,
283 	.bind		=	sock_no_bind,
284 	.accept		=	sock_no_accept,
285 
286 	.release	=	af_alg_release,
287 	.sendmsg	=	skcipher_sendmsg_nokey,
288 	.sendpage	=	skcipher_sendpage_nokey,
289 	.recvmsg	=	skcipher_recvmsg_nokey,
290 	.poll		=	af_alg_poll,
291 };
292 
skcipher_bind(const char * name,u32 type,u32 mask)293 static void *skcipher_bind(const char *name, u32 type, u32 mask)
294 {
295 	return crypto_alloc_skcipher(name, type, mask);
296 }
297 
skcipher_release(void * private)298 static void skcipher_release(void *private)
299 {
300 	crypto_free_skcipher(private);
301 }
302 
skcipher_setkey(void * private,const u8 * key,unsigned int keylen)303 static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
304 {
305 	return crypto_skcipher_setkey(private, key, keylen);
306 }
307 
skcipher_sock_destruct(struct sock * sk)308 static void skcipher_sock_destruct(struct sock *sk)
309 {
310 	struct alg_sock *ask = alg_sk(sk);
311 	struct af_alg_ctx *ctx = ask->private;
312 	struct sock *psk = ask->parent;
313 	struct alg_sock *pask = alg_sk(psk);
314 	struct crypto_skcipher *tfm = pask->private;
315 
316 	af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
317 	sock_kzfree_s(sk, ctx->iv, crypto_skcipher_ivsize(tfm));
318 	sock_kfree_s(sk, ctx, ctx->len);
319 	af_alg_release_parent(sk);
320 }
321 
skcipher_accept_parent_nokey(void * private,struct sock * sk)322 static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
323 {
324 	struct af_alg_ctx *ctx;
325 	struct alg_sock *ask = alg_sk(sk);
326 	struct crypto_skcipher *tfm = private;
327 	unsigned int len = sizeof(*ctx);
328 
329 	ctx = sock_kmalloc(sk, len, GFP_KERNEL);
330 	if (!ctx)
331 		return -ENOMEM;
332 	memset(ctx, 0, len);
333 
334 	ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(tfm),
335 			       GFP_KERNEL);
336 	if (!ctx->iv) {
337 		sock_kfree_s(sk, ctx, len);
338 		return -ENOMEM;
339 	}
340 	memset(ctx->iv, 0, crypto_skcipher_ivsize(tfm));
341 
342 	INIT_LIST_HEAD(&ctx->tsgl_list);
343 	ctx->len = len;
344 	crypto_init_wait(&ctx->wait);
345 
346 	ask->private = ctx;
347 
348 	sk->sk_destruct = skcipher_sock_destruct;
349 
350 	return 0;
351 }
352 
skcipher_accept_parent(void * private,struct sock * sk)353 static int skcipher_accept_parent(void *private, struct sock *sk)
354 {
355 	struct crypto_skcipher *tfm = private;
356 
357 	if (crypto_skcipher_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
358 		return -ENOKEY;
359 
360 	return skcipher_accept_parent_nokey(private, sk);
361 }
362 
363 static const struct af_alg_type algif_type_skcipher = {
364 	.bind		=	skcipher_bind,
365 	.release	=	skcipher_release,
366 	.setkey		=	skcipher_setkey,
367 	.accept		=	skcipher_accept_parent,
368 	.accept_nokey	=	skcipher_accept_parent_nokey,
369 	.ops		=	&algif_skcipher_ops,
370 	.ops_nokey	=	&algif_skcipher_ops_nokey,
371 	.name		=	"skcipher",
372 	.owner		=	THIS_MODULE
373 };
374 
algif_skcipher_init(void)375 static int __init algif_skcipher_init(void)
376 {
377 	return af_alg_register_type(&algif_type_skcipher);
378 }
379 
algif_skcipher_exit(void)380 static void __exit algif_skcipher_exit(void)
381 {
382 	int err = af_alg_unregister_type(&algif_type_skcipher);
383 	BUG_ON(err);
384 }
385 
386 module_init(algif_skcipher_init);
387 module_exit(algif_skcipher_exit);
388 MODULE_LICENSE("GPL");
389