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Stephan Mueller400c40c2015-02-28 20:50:00 +01001/*
2 * algif_aead: User-space interface for AEAD algorithms
3 *
4 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
5 *
6 * This file provides the user-space API for AEAD ciphers.
7 *
8 * This file is derived from algif_skcipher.c.
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the Free
12 * Software Foundation; either version 2 of the License, or (at your option)
13 * any later version.
14 */
15
Herbert Xu89081da2015-04-22 15:06:28 +080016#include <crypto/aead.h>
Stephan Mueller400c40c2015-02-28 20:50:00 +010017#include <crypto/scatterwalk.h>
18#include <crypto/if_alg.h>
19#include <linux/init.h>
20#include <linux/list.h>
21#include <linux/kernel.h>
22#include <linux/mm.h>
23#include <linux/module.h>
24#include <linux/net.h>
25#include <net/sock.h>
26
27struct aead_sg_list {
28 unsigned int cur;
29 struct scatterlist sg[ALG_MAX_PAGES];
30};
31
32struct aead_ctx {
33 struct aead_sg_list tsgl;
34 /*
35 * RSGL_MAX_ENTRIES is an artificial limit where user space at maximum
36 * can cause the kernel to allocate RSGL_MAX_ENTRIES * ALG_MAX_PAGES
Tadeusz Struk7b2a18e2015-05-15 10:18:37 -070037 * pages
Stephan Mueller400c40c2015-02-28 20:50:00 +010038 */
39#define RSGL_MAX_ENTRIES ALG_MAX_PAGES
40 struct af_alg_sgl rsgl[RSGL_MAX_ENTRIES];
41
42 void *iv;
43
44 struct af_alg_completion completion;
45
46 unsigned long used;
47
48 unsigned int len;
49 bool more;
50 bool merge;
51 bool enc;
52
53 size_t aead_assoclen;
54 struct aead_request aead_req;
55};
56
57static inline int aead_sndbuf(struct sock *sk)
58{
59 struct alg_sock *ask = alg_sk(sk);
60 struct aead_ctx *ctx = ask->private;
61
62 return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
63 ctx->used, 0);
64}
65
66static inline bool aead_writable(struct sock *sk)
67{
68 return PAGE_SIZE <= aead_sndbuf(sk);
69}
70
71static inline bool aead_sufficient_data(struct aead_ctx *ctx)
72{
73 unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
74
Herbert Xu19fa7752015-05-27 17:24:41 +080075 return ctx->used >= ctx->aead_assoclen + as;
Stephan Mueller400c40c2015-02-28 20:50:00 +010076}
77
78static void aead_put_sgl(struct sock *sk)
79{
80 struct alg_sock *ask = alg_sk(sk);
81 struct aead_ctx *ctx = ask->private;
82 struct aead_sg_list *sgl = &ctx->tsgl;
83 struct scatterlist *sg = sgl->sg;
84 unsigned int i;
85
86 for (i = 0; i < sgl->cur; i++) {
87 if (!sg_page(sg + i))
88 continue;
89
90 put_page(sg_page(sg + i));
91 sg_assign_page(sg + i, NULL);
92 }
93 sgl->cur = 0;
94 ctx->used = 0;
95 ctx->more = 0;
96 ctx->merge = 0;
97}
98
99static void aead_wmem_wakeup(struct sock *sk)
100{
101 struct socket_wq *wq;
102
103 if (!aead_writable(sk))
104 return;
105
106 rcu_read_lock();
107 wq = rcu_dereference(sk->sk_wq);
108 if (wq_has_sleeper(wq))
109 wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
110 POLLRDNORM |
111 POLLRDBAND);
112 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
113 rcu_read_unlock();
114}
115
116static int aead_wait_for_data(struct sock *sk, unsigned flags)
117{
118 struct alg_sock *ask = alg_sk(sk);
119 struct aead_ctx *ctx = ask->private;
120 long timeout;
121 DEFINE_WAIT(wait);
122 int err = -ERESTARTSYS;
123
124 if (flags & MSG_DONTWAIT)
125 return -EAGAIN;
126
127 set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
128
129 for (;;) {
130 if (signal_pending(current))
131 break;
132 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
133 timeout = MAX_SCHEDULE_TIMEOUT;
134 if (sk_wait_event(sk, &timeout, !ctx->more)) {
135 err = 0;
136 break;
137 }
138 }
139 finish_wait(sk_sleep(sk), &wait);
140
141 clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
142
143 return err;
144}
145
146static void aead_data_wakeup(struct sock *sk)
147{
148 struct alg_sock *ask = alg_sk(sk);
149 struct aead_ctx *ctx = ask->private;
150 struct socket_wq *wq;
151
152 if (ctx->more)
153 return;
154 if (!ctx->used)
155 return;
156
157 rcu_read_lock();
158 wq = rcu_dereference(sk->sk_wq);
159 if (wq_has_sleeper(wq))
160 wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
161 POLLRDNORM |
162 POLLRDBAND);
163 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
164 rcu_read_unlock();
165}
166
Linus Torvaldseccd02f2015-04-15 14:09:46 -0700167static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
Stephan Mueller400c40c2015-02-28 20:50:00 +0100168{
169 struct sock *sk = sock->sk;
170 struct alg_sock *ask = alg_sk(sk);
171 struct aead_ctx *ctx = ask->private;
172 unsigned ivsize =
173 crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req));
174 struct aead_sg_list *sgl = &ctx->tsgl;
175 struct af_alg_control con = {};
176 long copied = 0;
177 bool enc = 0;
178 bool init = 0;
179 int err = -EINVAL;
180
181 if (msg->msg_controllen) {
182 err = af_alg_cmsg_send(msg, &con);
183 if (err)
184 return err;
185
186 init = 1;
187 switch (con.op) {
188 case ALG_OP_ENCRYPT:
189 enc = 1;
190 break;
191 case ALG_OP_DECRYPT:
192 enc = 0;
193 break;
194 default:
195 return -EINVAL;
196 }
197
198 if (con.iv && con.iv->ivlen != ivsize)
199 return -EINVAL;
200 }
201
202 lock_sock(sk);
203 if (!ctx->more && ctx->used)
204 goto unlock;
205
206 if (init) {
207 ctx->enc = enc;
208 if (con.iv)
209 memcpy(ctx->iv, con.iv->iv, ivsize);
210
211 ctx->aead_assoclen = con.aead_assoclen;
212 }
213
214 while (size) {
215 unsigned long len = size;
216 struct scatterlist *sg = NULL;
217
218 /* use the existing memory in an allocated page */
219 if (ctx->merge) {
220 sg = sgl->sg + sgl->cur - 1;
221 len = min_t(unsigned long, len,
222 PAGE_SIZE - sg->offset - sg->length);
223 err = memcpy_from_msg(page_address(sg_page(sg)) +
224 sg->offset + sg->length,
225 msg, len);
226 if (err)
227 goto unlock;
228
229 sg->length += len;
230 ctx->merge = (sg->offset + sg->length) &
231 (PAGE_SIZE - 1);
232
233 ctx->used += len;
234 copied += len;
235 size -= len;
236 continue;
237 }
238
239 if (!aead_writable(sk)) {
240 /* user space sent too much data */
241 aead_put_sgl(sk);
242 err = -EMSGSIZE;
243 goto unlock;
244 }
245
246 /* allocate a new page */
247 len = min_t(unsigned long, size, aead_sndbuf(sk));
248 while (len) {
249 int plen = 0;
250
251 if (sgl->cur >= ALG_MAX_PAGES) {
252 aead_put_sgl(sk);
253 err = -E2BIG;
254 goto unlock;
255 }
256
257 sg = sgl->sg + sgl->cur;
258 plen = min_t(int, len, PAGE_SIZE);
259
260 sg_assign_page(sg, alloc_page(GFP_KERNEL));
261 err = -ENOMEM;
262 if (!sg_page(sg))
263 goto unlock;
264
265 err = memcpy_from_msg(page_address(sg_page(sg)),
266 msg, plen);
267 if (err) {
268 __free_page(sg_page(sg));
269 sg_assign_page(sg, NULL);
270 goto unlock;
271 }
272
273 sg->offset = 0;
274 sg->length = plen;
275 len -= plen;
276 ctx->used += plen;
277 copied += plen;
278 sgl->cur++;
279 size -= plen;
280 ctx->merge = plen & (PAGE_SIZE - 1);
281 }
282 }
283
284 err = 0;
285
286 ctx->more = msg->msg_flags & MSG_MORE;
287 if (!ctx->more && !aead_sufficient_data(ctx)) {
288 aead_put_sgl(sk);
289 err = -EMSGSIZE;
290 }
291
292unlock:
293 aead_data_wakeup(sk);
294 release_sock(sk);
295
296 return err ?: copied;
297}
298
299static ssize_t aead_sendpage(struct socket *sock, struct page *page,
300 int offset, size_t size, int flags)
301{
302 struct sock *sk = sock->sk;
303 struct alg_sock *ask = alg_sk(sk);
304 struct aead_ctx *ctx = ask->private;
305 struct aead_sg_list *sgl = &ctx->tsgl;
306 int err = -EINVAL;
307
308 if (flags & MSG_SENDPAGE_NOTLAST)
309 flags |= MSG_MORE;
310
311 if (sgl->cur >= ALG_MAX_PAGES)
312 return -E2BIG;
313
314 lock_sock(sk);
315 if (!ctx->more && ctx->used)
316 goto unlock;
317
318 if (!size)
319 goto done;
320
321 if (!aead_writable(sk)) {
322 /* user space sent too much data */
323 aead_put_sgl(sk);
324 err = -EMSGSIZE;
325 goto unlock;
326 }
327
328 ctx->merge = 0;
329
330 get_page(page);
331 sg_set_page(sgl->sg + sgl->cur, page, size, offset);
332 sgl->cur++;
333 ctx->used += size;
334
335 err = 0;
336
337done:
338 ctx->more = flags & MSG_MORE;
339 if (!ctx->more && !aead_sufficient_data(ctx)) {
340 aead_put_sgl(sk);
341 err = -EMSGSIZE;
342 }
343
344unlock:
345 aead_data_wakeup(sk);
346 release_sock(sk);
347
348 return err ?: size;
349}
350
Linus Torvaldseccd02f2015-04-15 14:09:46 -0700351static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored, int flags)
Stephan Mueller400c40c2015-02-28 20:50:00 +0100352{
353 struct sock *sk = sock->sk;
354 struct alg_sock *ask = alg_sk(sk);
355 struct aead_ctx *ctx = ask->private;
Stephan Mueller400c40c2015-02-28 20:50:00 +0100356 unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
357 struct aead_sg_list *sgl = &ctx->tsgl;
Stephan Mueller400c40c2015-02-28 20:50:00 +0100358 unsigned int i = 0;
359 int err = -EINVAL;
360 unsigned long used = 0;
361 size_t outlen = 0;
362 size_t usedpages = 0;
363 unsigned int cnt = 0;
364
365 /* Limit number of IOV blocks to be accessed below */
366 if (msg->msg_iter.nr_segs > RSGL_MAX_ENTRIES)
367 return -ENOMSG;
368
369 lock_sock(sk);
370
371 /*
372 * AEAD memory structure: For encryption, the tag is appended to the
373 * ciphertext which implies that the memory allocated for the ciphertext
374 * must be increased by the tag length. For decryption, the tag
375 * is expected to be concatenated to the ciphertext. The plaintext
376 * therefore has a memory size of the ciphertext minus the tag length.
377 *
378 * The memory structure for cipher operation has the following
379 * structure:
380 * AEAD encryption input: assoc data || plaintext
381 * AEAD encryption output: cipherntext || auth tag
382 * AEAD decryption input: assoc data || ciphertext || auth tag
383 * AEAD decryption output: plaintext
384 */
385
386 if (ctx->more) {
387 err = aead_wait_for_data(sk, flags);
388 if (err)
389 goto unlock;
390 }
391
392 used = ctx->used;
393
394 /*
395 * Make sure sufficient data is present -- note, the same check is
396 * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg
397 * shall provide an information to the data sender that something is
398 * wrong, but they are irrelevant to maintain the kernel integrity.
399 * We need this check here too in case user space decides to not honor
400 * the error message in sendmsg/sendpage and still call recvmsg. This
401 * check here protects the kernel integrity.
402 */
403 if (!aead_sufficient_data(ctx))
404 goto unlock;
405
Herbert Xu19fa7752015-05-27 17:24:41 +0800406 outlen = used;
407
Stephan Mueller400c40c2015-02-28 20:50:00 +0100408 /*
409 * The cipher operation input data is reduced by the associated data
410 * length as this data is processed separately later on.
411 */
Herbert Xu19fa7752015-05-27 17:24:41 +0800412 used -= ctx->aead_assoclen + (ctx->enc ? as : 0);
Stephan Mueller400c40c2015-02-28 20:50:00 +0100413
414 /* convert iovecs of output buffers into scatterlists */
415 while (iov_iter_count(&msg->msg_iter)) {
416 size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
417 (outlen - usedpages));
418
419 /* make one iovec available as scatterlist */
420 err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter,
421 seglen);
422 if (err < 0)
423 goto unlock;
424 usedpages += err;
Tadeusz Struk7b2a18e2015-05-15 10:18:37 -0700425 /* chain the new scatterlist with previous one */
Stephan Mueller400c40c2015-02-28 20:50:00 +0100426 if (cnt)
Tadeusz Struk7b2a18e2015-05-15 10:18:37 -0700427 af_alg_link_sg(&ctx->rsgl[cnt-1], &ctx->rsgl[cnt]);
428
Stephan Mueller400c40c2015-02-28 20:50:00 +0100429 /* we do not need more iovecs as we have sufficient memory */
430 if (outlen <= usedpages)
431 break;
432 iov_iter_advance(&msg->msg_iter, err);
433 cnt++;
434 }
435
436 err = -EINVAL;
437 /* ensure output buffer is sufficiently large */
438 if (usedpages < outlen)
439 goto unlock;
440
Herbert Xu19fa7752015-05-27 17:24:41 +0800441 sg_mark_end(sgl->sg + sgl->cur - 1);
Stephan Mueller400c40c2015-02-28 20:50:00 +0100442
Herbert Xu19fa7752015-05-27 17:24:41 +0800443 aead_request_set_crypt(&ctx->aead_req, sgl->sg, ctx->rsgl[0].sg,
444 used, ctx->iv);
445 aead_request_set_ad(&ctx->aead_req, ctx->aead_assoclen);
Stephan Mueller400c40c2015-02-28 20:50:00 +0100446
447 err = af_alg_wait_for_completion(ctx->enc ?
448 crypto_aead_encrypt(&ctx->aead_req) :
449 crypto_aead_decrypt(&ctx->aead_req),
450 &ctx->completion);
451
452 if (err) {
453 /* EBADMSG implies a valid cipher operation took place */
454 if (err == -EBADMSG)
455 aead_put_sgl(sk);
456 goto unlock;
457 }
458
459 aead_put_sgl(sk);
460
461 err = 0;
462
463unlock:
464 for (i = 0; i < cnt; i++)
465 af_alg_free_sg(&ctx->rsgl[i]);
466
467 aead_wmem_wakeup(sk);
468 release_sock(sk);
469
470 return err ? err : outlen;
471}
472
473static unsigned int aead_poll(struct file *file, struct socket *sock,
474 poll_table *wait)
475{
476 struct sock *sk = sock->sk;
477 struct alg_sock *ask = alg_sk(sk);
478 struct aead_ctx *ctx = ask->private;
479 unsigned int mask;
480
481 sock_poll_wait(file, sk_sleep(sk), wait);
482 mask = 0;
483
484 if (!ctx->more)
485 mask |= POLLIN | POLLRDNORM;
486
487 if (aead_writable(sk))
488 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
489
490 return mask;
491}
492
493static struct proto_ops algif_aead_ops = {
494 .family = PF_ALG,
495
496 .connect = sock_no_connect,
497 .socketpair = sock_no_socketpair,
498 .getname = sock_no_getname,
499 .ioctl = sock_no_ioctl,
500 .listen = sock_no_listen,
501 .shutdown = sock_no_shutdown,
502 .getsockopt = sock_no_getsockopt,
503 .mmap = sock_no_mmap,
504 .bind = sock_no_bind,
505 .accept = sock_no_accept,
506 .setsockopt = sock_no_setsockopt,
507
508 .release = af_alg_release,
509 .sendmsg = aead_sendmsg,
510 .sendpage = aead_sendpage,
511 .recvmsg = aead_recvmsg,
512 .poll = aead_poll,
513};
514
515static void *aead_bind(const char *name, u32 type, u32 mask)
516{
Herbert Xu3e909502015-06-22 10:31:40 +0800517 return crypto_alloc_aead(name, type | CRYPTO_ALG_AEAD_NEW,
518 mask | CRYPTO_ALG_AEAD_NEW);
Stephan Mueller400c40c2015-02-28 20:50:00 +0100519}
520
521static void aead_release(void *private)
522{
523 crypto_free_aead(private);
524}
525
526static int aead_setauthsize(void *private, unsigned int authsize)
527{
528 return crypto_aead_setauthsize(private, authsize);
529}
530
531static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
532{
533 return crypto_aead_setkey(private, key, keylen);
534}
535
536static void aead_sock_destruct(struct sock *sk)
537{
538 struct alg_sock *ask = alg_sk(sk);
539 struct aead_ctx *ctx = ask->private;
540 unsigned int ivlen = crypto_aead_ivsize(
541 crypto_aead_reqtfm(&ctx->aead_req));
542
543 aead_put_sgl(sk);
544 sock_kzfree_s(sk, ctx->iv, ivlen);
545 sock_kfree_s(sk, ctx, ctx->len);
546 af_alg_release_parent(sk);
547}
548
549static int aead_accept_parent(void *private, struct sock *sk)
550{
551 struct aead_ctx *ctx;
552 struct alg_sock *ask = alg_sk(sk);
553 unsigned int len = sizeof(*ctx) + crypto_aead_reqsize(private);
554 unsigned int ivlen = crypto_aead_ivsize(private);
555
556 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
557 if (!ctx)
558 return -ENOMEM;
559 memset(ctx, 0, len);
560
561 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
562 if (!ctx->iv) {
563 sock_kfree_s(sk, ctx, len);
564 return -ENOMEM;
565 }
566 memset(ctx->iv, 0, ivlen);
567
568 ctx->len = len;
569 ctx->used = 0;
570 ctx->more = 0;
571 ctx->merge = 0;
572 ctx->enc = 0;
573 ctx->tsgl.cur = 0;
574 ctx->aead_assoclen = 0;
575 af_alg_init_completion(&ctx->completion);
576 sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
577
578 ask->private = ctx;
579
580 aead_request_set_tfm(&ctx->aead_req, private);
581 aead_request_set_callback(&ctx->aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
582 af_alg_complete, &ctx->completion);
583
584 sk->sk_destruct = aead_sock_destruct;
585
586 return 0;
587}
588
589static const struct af_alg_type algif_type_aead = {
590 .bind = aead_bind,
591 .release = aead_release,
592 .setkey = aead_setkey,
593 .setauthsize = aead_setauthsize,
594 .accept = aead_accept_parent,
595 .ops = &algif_aead_ops,
596 .name = "aead",
597 .owner = THIS_MODULE
598};
599
600static int __init algif_aead_init(void)
601{
602 return af_alg_register_type(&algif_type_aead);
603}
604
605static void __exit algif_aead_exit(void)
606{
607 int err = af_alg_unregister_type(&algif_type_aead);
608 BUG_ON(err);
609}
610
611module_init(algif_aead_init);
612module_exit(algif_aead_exit);
613MODULE_LICENSE("GPL");
614MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
615MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");