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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
16#include <crypto/scatterwalk.h>
17#include <crypto/if_alg.h>
18#include <linux/init.h>
19#include <linux/list.h>
20#include <linux/kernel.h>
21#include <linux/mm.h>
22#include <linux/module.h>
23#include <linux/net.h>
24#include <net/sock.h>
25
26struct aead_sg_list {
27 unsigned int cur;
28 struct scatterlist sg[ALG_MAX_PAGES];
29};
30
31struct aead_ctx {
32 struct aead_sg_list tsgl;
33 /*
34 * RSGL_MAX_ENTRIES is an artificial limit where user space at maximum
35 * can cause the kernel to allocate RSGL_MAX_ENTRIES * ALG_MAX_PAGES
Tadeusz Struk7b2a18e2015-05-15 10:18:37 -070036 * pages
Stephan Mueller400c40c2015-02-28 20:50:00 +010037 */
38#define RSGL_MAX_ENTRIES ALG_MAX_PAGES
39 struct af_alg_sgl rsgl[RSGL_MAX_ENTRIES];
40
41 void *iv;
42
43 struct af_alg_completion completion;
44
45 unsigned long used;
46
47 unsigned int len;
48 bool more;
49 bool merge;
50 bool enc;
51
52 size_t aead_assoclen;
53 struct aead_request aead_req;
54};
55
56static inline int aead_sndbuf(struct sock *sk)
57{
58 struct alg_sock *ask = alg_sk(sk);
59 struct aead_ctx *ctx = ask->private;
60
61 return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
62 ctx->used, 0);
63}
64
65static inline bool aead_writable(struct sock *sk)
66{
67 return PAGE_SIZE <= aead_sndbuf(sk);
68}
69
70static inline bool aead_sufficient_data(struct aead_ctx *ctx)
71{
72 unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
73
74 return (ctx->used >= (ctx->aead_assoclen + (ctx->enc ? 0 : as)));
75}
76
77static void aead_put_sgl(struct sock *sk)
78{
79 struct alg_sock *ask = alg_sk(sk);
80 struct aead_ctx *ctx = ask->private;
81 struct aead_sg_list *sgl = &ctx->tsgl;
82 struct scatterlist *sg = sgl->sg;
83 unsigned int i;
84
85 for (i = 0; i < sgl->cur; i++) {
86 if (!sg_page(sg + i))
87 continue;
88
89 put_page(sg_page(sg + i));
90 sg_assign_page(sg + i, NULL);
91 }
92 sgl->cur = 0;
93 ctx->used = 0;
94 ctx->more = 0;
95 ctx->merge = 0;
96}
97
98static void aead_wmem_wakeup(struct sock *sk)
99{
100 struct socket_wq *wq;
101
102 if (!aead_writable(sk))
103 return;
104
105 rcu_read_lock();
106 wq = rcu_dereference(sk->sk_wq);
107 if (wq_has_sleeper(wq))
108 wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
109 POLLRDNORM |
110 POLLRDBAND);
111 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
112 rcu_read_unlock();
113}
114
115static int aead_wait_for_data(struct sock *sk, unsigned flags)
116{
117 struct alg_sock *ask = alg_sk(sk);
118 struct aead_ctx *ctx = ask->private;
119 long timeout;
120 DEFINE_WAIT(wait);
121 int err = -ERESTARTSYS;
122
123 if (flags & MSG_DONTWAIT)
124 return -EAGAIN;
125
126 set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
127
128 for (;;) {
129 if (signal_pending(current))
130 break;
131 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
132 timeout = MAX_SCHEDULE_TIMEOUT;
133 if (sk_wait_event(sk, &timeout, !ctx->more)) {
134 err = 0;
135 break;
136 }
137 }
138 finish_wait(sk_sleep(sk), &wait);
139
140 clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
141
142 return err;
143}
144
145static void aead_data_wakeup(struct sock *sk)
146{
147 struct alg_sock *ask = alg_sk(sk);
148 struct aead_ctx *ctx = ask->private;
149 struct socket_wq *wq;
150
151 if (ctx->more)
152 return;
153 if (!ctx->used)
154 return;
155
156 rcu_read_lock();
157 wq = rcu_dereference(sk->sk_wq);
158 if (wq_has_sleeper(wq))
159 wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
160 POLLRDNORM |
161 POLLRDBAND);
162 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
163 rcu_read_unlock();
164}
165
Linus Torvaldseccd02f2015-04-15 14:09:46 -0700166static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
Stephan Mueller400c40c2015-02-28 20:50:00 +0100167{
168 struct sock *sk = sock->sk;
169 struct alg_sock *ask = alg_sk(sk);
170 struct aead_ctx *ctx = ask->private;
171 unsigned ivsize =
172 crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req));
173 struct aead_sg_list *sgl = &ctx->tsgl;
174 struct af_alg_control con = {};
175 long copied = 0;
176 bool enc = 0;
177 bool init = 0;
178 int err = -EINVAL;
179
180 if (msg->msg_controllen) {
181 err = af_alg_cmsg_send(msg, &con);
182 if (err)
183 return err;
184
185 init = 1;
186 switch (con.op) {
187 case ALG_OP_ENCRYPT:
188 enc = 1;
189 break;
190 case ALG_OP_DECRYPT:
191 enc = 0;
192 break;
193 default:
194 return -EINVAL;
195 }
196
197 if (con.iv && con.iv->ivlen != ivsize)
198 return -EINVAL;
199 }
200
201 lock_sock(sk);
202 if (!ctx->more && ctx->used)
203 goto unlock;
204
205 if (init) {
206 ctx->enc = enc;
207 if (con.iv)
208 memcpy(ctx->iv, con.iv->iv, ivsize);
209
210 ctx->aead_assoclen = con.aead_assoclen;
211 }
212
213 while (size) {
214 unsigned long len = size;
215 struct scatterlist *sg = NULL;
216
217 /* use the existing memory in an allocated page */
218 if (ctx->merge) {
219 sg = sgl->sg + sgl->cur - 1;
220 len = min_t(unsigned long, len,
221 PAGE_SIZE - sg->offset - sg->length);
222 err = memcpy_from_msg(page_address(sg_page(sg)) +
223 sg->offset + sg->length,
224 msg, len);
225 if (err)
226 goto unlock;
227
228 sg->length += len;
229 ctx->merge = (sg->offset + sg->length) &
230 (PAGE_SIZE - 1);
231
232 ctx->used += len;
233 copied += len;
234 size -= len;
235 continue;
236 }
237
238 if (!aead_writable(sk)) {
239 /* user space sent too much data */
240 aead_put_sgl(sk);
241 err = -EMSGSIZE;
242 goto unlock;
243 }
244
245 /* allocate a new page */
246 len = min_t(unsigned long, size, aead_sndbuf(sk));
247 while (len) {
248 int plen = 0;
249
250 if (sgl->cur >= ALG_MAX_PAGES) {
251 aead_put_sgl(sk);
252 err = -E2BIG;
253 goto unlock;
254 }
255
256 sg = sgl->sg + sgl->cur;
257 plen = min_t(int, len, PAGE_SIZE);
258
259 sg_assign_page(sg, alloc_page(GFP_KERNEL));
260 err = -ENOMEM;
261 if (!sg_page(sg))
262 goto unlock;
263
264 err = memcpy_from_msg(page_address(sg_page(sg)),
265 msg, plen);
266 if (err) {
267 __free_page(sg_page(sg));
268 sg_assign_page(sg, NULL);
269 goto unlock;
270 }
271
272 sg->offset = 0;
273 sg->length = plen;
274 len -= plen;
275 ctx->used += plen;
276 copied += plen;
277 sgl->cur++;
278 size -= plen;
279 ctx->merge = plen & (PAGE_SIZE - 1);
280 }
281 }
282
283 err = 0;
284
285 ctx->more = msg->msg_flags & MSG_MORE;
286 if (!ctx->more && !aead_sufficient_data(ctx)) {
287 aead_put_sgl(sk);
288 err = -EMSGSIZE;
289 }
290
291unlock:
292 aead_data_wakeup(sk);
293 release_sock(sk);
294
295 return err ?: copied;
296}
297
298static ssize_t aead_sendpage(struct socket *sock, struct page *page,
299 int offset, size_t size, int flags)
300{
301 struct sock *sk = sock->sk;
302 struct alg_sock *ask = alg_sk(sk);
303 struct aead_ctx *ctx = ask->private;
304 struct aead_sg_list *sgl = &ctx->tsgl;
305 int err = -EINVAL;
306
307 if (flags & MSG_SENDPAGE_NOTLAST)
308 flags |= MSG_MORE;
309
310 if (sgl->cur >= ALG_MAX_PAGES)
311 return -E2BIG;
312
313 lock_sock(sk);
314 if (!ctx->more && ctx->used)
315 goto unlock;
316
317 if (!size)
318 goto done;
319
320 if (!aead_writable(sk)) {
321 /* user space sent too much data */
322 aead_put_sgl(sk);
323 err = -EMSGSIZE;
324 goto unlock;
325 }
326
327 ctx->merge = 0;
328
329 get_page(page);
330 sg_set_page(sgl->sg + sgl->cur, page, size, offset);
331 sgl->cur++;
332 ctx->used += size;
333
334 err = 0;
335
336done:
337 ctx->more = flags & MSG_MORE;
338 if (!ctx->more && !aead_sufficient_data(ctx)) {
339 aead_put_sgl(sk);
340 err = -EMSGSIZE;
341 }
342
343unlock:
344 aead_data_wakeup(sk);
345 release_sock(sk);
346
347 return err ?: size;
348}
349
Linus Torvaldseccd02f2015-04-15 14:09:46 -0700350static int aead_recvmsg(struct socket *sock, struct msghdr *msg, size_t ignored, int flags)
Stephan Mueller400c40c2015-02-28 20:50:00 +0100351{
352 struct sock *sk = sock->sk;
353 struct alg_sock *ask = alg_sk(sk);
354 struct aead_ctx *ctx = ask->private;
355 unsigned bs = crypto_aead_blocksize(crypto_aead_reqtfm(&ctx->aead_req));
356 unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
357 struct aead_sg_list *sgl = &ctx->tsgl;
358 struct scatterlist *sg = NULL;
359 struct scatterlist assoc[ALG_MAX_PAGES];
360 size_t assoclen = 0;
361 unsigned int i = 0;
362 int err = -EINVAL;
363 unsigned long used = 0;
364 size_t outlen = 0;
365 size_t usedpages = 0;
366 unsigned int cnt = 0;
367
368 /* Limit number of IOV blocks to be accessed below */
369 if (msg->msg_iter.nr_segs > RSGL_MAX_ENTRIES)
370 return -ENOMSG;
371
372 lock_sock(sk);
373
374 /*
375 * AEAD memory structure: For encryption, the tag is appended to the
376 * ciphertext which implies that the memory allocated for the ciphertext
377 * must be increased by the tag length. For decryption, the tag
378 * is expected to be concatenated to the ciphertext. The plaintext
379 * therefore has a memory size of the ciphertext minus the tag length.
380 *
381 * The memory structure for cipher operation has the following
382 * structure:
383 * AEAD encryption input: assoc data || plaintext
384 * AEAD encryption output: cipherntext || auth tag
385 * AEAD decryption input: assoc data || ciphertext || auth tag
386 * AEAD decryption output: plaintext
387 */
388
389 if (ctx->more) {
390 err = aead_wait_for_data(sk, flags);
391 if (err)
392 goto unlock;
393 }
394
395 used = ctx->used;
396
397 /*
398 * Make sure sufficient data is present -- note, the same check is
399 * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg
400 * shall provide an information to the data sender that something is
401 * wrong, but they are irrelevant to maintain the kernel integrity.
402 * We need this check here too in case user space decides to not honor
403 * the error message in sendmsg/sendpage and still call recvmsg. This
404 * check here protects the kernel integrity.
405 */
406 if (!aead_sufficient_data(ctx))
407 goto unlock;
408
409 /*
410 * The cipher operation input data is reduced by the associated data
411 * length as this data is processed separately later on.
412 */
413 used -= ctx->aead_assoclen;
414
415 if (ctx->enc) {
416 /* round up output buffer to multiple of block size */
417 outlen = ((used + bs - 1) / bs * bs);
418 /* add the size needed for the auth tag to be created */
419 outlen += as;
420 } else {
421 /* output data size is input without the authentication tag */
422 outlen = used - as;
423 /* round up output buffer to multiple of block size */
424 outlen = ((outlen + bs - 1) / bs * bs);
425 }
426
427 /* convert iovecs of output buffers into scatterlists */
428 while (iov_iter_count(&msg->msg_iter)) {
429 size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
430 (outlen - usedpages));
431
432 /* make one iovec available as scatterlist */
433 err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter,
434 seglen);
435 if (err < 0)
436 goto unlock;
437 usedpages += err;
Tadeusz Struk7b2a18e2015-05-15 10:18:37 -0700438 /* chain the new scatterlist with previous one */
Stephan Mueller400c40c2015-02-28 20:50:00 +0100439 if (cnt)
Tadeusz Struk7b2a18e2015-05-15 10:18:37 -0700440 af_alg_link_sg(&ctx->rsgl[cnt-1], &ctx->rsgl[cnt]);
441
Stephan Mueller400c40c2015-02-28 20:50:00 +0100442 /* we do not need more iovecs as we have sufficient memory */
443 if (outlen <= usedpages)
444 break;
445 iov_iter_advance(&msg->msg_iter, err);
446 cnt++;
447 }
448
449 err = -EINVAL;
450 /* ensure output buffer is sufficiently large */
451 if (usedpages < outlen)
452 goto unlock;
453
454 sg_init_table(assoc, ALG_MAX_PAGES);
455 assoclen = ctx->aead_assoclen;
456 /*
457 * Split scatterlist into two: first part becomes AD, second part
458 * is plaintext / ciphertext. The first part is assigned to assoc
459 * scatterlist. When this loop finishes, sg points to the start of the
460 * plaintext / ciphertext.
461 */
462 for (i = 0; i < ctx->tsgl.cur; i++) {
463 sg = sgl->sg + i;
464 if (sg->length <= assoclen) {
465 /* AD is larger than one page */
466 sg_set_page(assoc + i, sg_page(sg),
467 sg->length, sg->offset);
468 assoclen -= sg->length;
469 if (i >= ctx->tsgl.cur)
470 goto unlock;
471 } else if (!assoclen) {
472 /* current page is to start of plaintext / ciphertext */
473 if (i)
474 /* AD terminates at page boundary */
475 sg_mark_end(assoc + i - 1);
476 else
477 /* AD size is zero */
478 sg_mark_end(assoc);
479 break;
480 } else {
481 /* AD does not terminate at page boundary */
482 sg_set_page(assoc + i, sg_page(sg),
483 assoclen, sg->offset);
484 sg_mark_end(assoc + i);
485 /* plaintext / ciphertext starts after AD */
486 sg->length -= assoclen;
487 sg->offset += assoclen;
488 break;
489 }
490 }
491
492 aead_request_set_assoc(&ctx->aead_req, assoc, ctx->aead_assoclen);
493 aead_request_set_crypt(&ctx->aead_req, sg, ctx->rsgl[0].sg, used,
494 ctx->iv);
495
496 err = af_alg_wait_for_completion(ctx->enc ?
497 crypto_aead_encrypt(&ctx->aead_req) :
498 crypto_aead_decrypt(&ctx->aead_req),
499 &ctx->completion);
500
501 if (err) {
502 /* EBADMSG implies a valid cipher operation took place */
503 if (err == -EBADMSG)
504 aead_put_sgl(sk);
505 goto unlock;
506 }
507
508 aead_put_sgl(sk);
509
510 err = 0;
511
512unlock:
513 for (i = 0; i < cnt; i++)
514 af_alg_free_sg(&ctx->rsgl[i]);
515
516 aead_wmem_wakeup(sk);
517 release_sock(sk);
518
519 return err ? err : outlen;
520}
521
522static unsigned int aead_poll(struct file *file, struct socket *sock,
523 poll_table *wait)
524{
525 struct sock *sk = sock->sk;
526 struct alg_sock *ask = alg_sk(sk);
527 struct aead_ctx *ctx = ask->private;
528 unsigned int mask;
529
530 sock_poll_wait(file, sk_sleep(sk), wait);
531 mask = 0;
532
533 if (!ctx->more)
534 mask |= POLLIN | POLLRDNORM;
535
536 if (aead_writable(sk))
537 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
538
539 return mask;
540}
541
542static struct proto_ops algif_aead_ops = {
543 .family = PF_ALG,
544
545 .connect = sock_no_connect,
546 .socketpair = sock_no_socketpair,
547 .getname = sock_no_getname,
548 .ioctl = sock_no_ioctl,
549 .listen = sock_no_listen,
550 .shutdown = sock_no_shutdown,
551 .getsockopt = sock_no_getsockopt,
552 .mmap = sock_no_mmap,
553 .bind = sock_no_bind,
554 .accept = sock_no_accept,
555 .setsockopt = sock_no_setsockopt,
556
557 .release = af_alg_release,
558 .sendmsg = aead_sendmsg,
559 .sendpage = aead_sendpage,
560 .recvmsg = aead_recvmsg,
561 .poll = aead_poll,
562};
563
564static void *aead_bind(const char *name, u32 type, u32 mask)
565{
566 return crypto_alloc_aead(name, type, mask);
567}
568
569static void aead_release(void *private)
570{
571 crypto_free_aead(private);
572}
573
574static int aead_setauthsize(void *private, unsigned int authsize)
575{
576 return crypto_aead_setauthsize(private, authsize);
577}
578
579static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
580{
581 return crypto_aead_setkey(private, key, keylen);
582}
583
584static void aead_sock_destruct(struct sock *sk)
585{
586 struct alg_sock *ask = alg_sk(sk);
587 struct aead_ctx *ctx = ask->private;
588 unsigned int ivlen = crypto_aead_ivsize(
589 crypto_aead_reqtfm(&ctx->aead_req));
590
591 aead_put_sgl(sk);
592 sock_kzfree_s(sk, ctx->iv, ivlen);
593 sock_kfree_s(sk, ctx, ctx->len);
594 af_alg_release_parent(sk);
595}
596
597static int aead_accept_parent(void *private, struct sock *sk)
598{
599 struct aead_ctx *ctx;
600 struct alg_sock *ask = alg_sk(sk);
601 unsigned int len = sizeof(*ctx) + crypto_aead_reqsize(private);
602 unsigned int ivlen = crypto_aead_ivsize(private);
603
604 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
605 if (!ctx)
606 return -ENOMEM;
607 memset(ctx, 0, len);
608
609 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
610 if (!ctx->iv) {
611 sock_kfree_s(sk, ctx, len);
612 return -ENOMEM;
613 }
614 memset(ctx->iv, 0, ivlen);
615
616 ctx->len = len;
617 ctx->used = 0;
618 ctx->more = 0;
619 ctx->merge = 0;
620 ctx->enc = 0;
621 ctx->tsgl.cur = 0;
622 ctx->aead_assoclen = 0;
623 af_alg_init_completion(&ctx->completion);
624 sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
625
626 ask->private = ctx;
627
628 aead_request_set_tfm(&ctx->aead_req, private);
629 aead_request_set_callback(&ctx->aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
630 af_alg_complete, &ctx->completion);
631
632 sk->sk_destruct = aead_sock_destruct;
633
634 return 0;
635}
636
637static const struct af_alg_type algif_type_aead = {
638 .bind = aead_bind,
639 .release = aead_release,
640 .setkey = aead_setkey,
641 .setauthsize = aead_setauthsize,
642 .accept = aead_accept_parent,
643 .ops = &algif_aead_ops,
644 .name = "aead",
645 .owner = THIS_MODULE
646};
647
648static int __init algif_aead_init(void)
649{
650 return af_alg_register_type(&algif_type_aead);
651}
652
653static void __exit algif_aead_exit(void)
654{
655 int err = af_alg_unregister_type(&algif_type_aead);
656 BUG_ON(err);
657}
658
659module_init(algif_aead_init);
660module_exit(algif_aead_exit);
661MODULE_LICENSE("GPL");
662MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
663MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");