2 * algif_aead: User-space interface for AEAD algorithms
4 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
6 * This file provides the user-space API for AEAD ciphers.
8 * This file is derived from algif_skcipher.c.
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)
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>
22 #include <linux/module.h>
23 #include <linux/net.h>
28 struct scatterlist sg[ALG_MAX_PAGES];
32 struct aead_sg_list tsgl;
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
38 #define RSGL_MAX_ENTRIES ALG_MAX_PAGES
39 struct af_alg_sgl rsgl[RSGL_MAX_ENTRIES];
43 struct af_alg_completion completion;
53 struct aead_request aead_req;
56 static inline int aead_sndbuf(struct sock *sk)
58 struct alg_sock *ask = alg_sk(sk);
59 struct aead_ctx *ctx = ask->private;
61 return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
65 static inline bool aead_writable(struct sock *sk)
67 return PAGE_SIZE <= aead_sndbuf(sk);
70 static inline bool aead_sufficient_data(struct aead_ctx *ctx)
72 unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
74 return (ctx->used >= (ctx->aead_assoclen + (ctx->enc ? 0 : as)));
77 static void aead_put_sgl(struct sock *sk)
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;
85 for (i = 0; i < sgl->cur; i++) {
89 put_page(sg_page(sg + i));
90 sg_assign_page(sg + i, NULL);
98 static void aead_wmem_wakeup(struct sock *sk)
100 struct socket_wq *wq;
102 if (!aead_writable(sk))
106 wq = rcu_dereference(sk->sk_wq);
107 if (wq_has_sleeper(wq))
108 wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
111 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
115 static int aead_wait_for_data(struct sock *sk, unsigned flags)
117 struct alg_sock *ask = alg_sk(sk);
118 struct aead_ctx *ctx = ask->private;
121 int err = -ERESTARTSYS;
123 if (flags & MSG_DONTWAIT)
126 set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
129 if (signal_pending(current))
131 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
132 timeout = MAX_SCHEDULE_TIMEOUT;
133 if (sk_wait_event(sk, &timeout, !ctx->more)) {
138 finish_wait(sk_sleep(sk), &wait);
140 clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
145 static void aead_data_wakeup(struct sock *sk)
147 struct alg_sock *ask = alg_sk(sk);
148 struct aead_ctx *ctx = ask->private;
149 struct socket_wq *wq;
157 wq = rcu_dereference(sk->sk_wq);
158 if (wq_has_sleeper(wq))
159 wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
162 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
166 static int aead_sendmsg(struct kiocb *unused, struct socket *sock,
167 struct msghdr *msg, size_t size)
169 struct sock *sk = sock->sk;
170 struct alg_sock *ask = alg_sk(sk);
171 struct aead_ctx *ctx = ask->private;
173 crypto_aead_ivsize(crypto_aead_reqtfm(&ctx->aead_req));
174 struct aead_sg_list *sgl = &ctx->tsgl;
175 struct af_alg_control con = {};
181 if (msg->msg_controllen) {
182 err = af_alg_cmsg_send(msg, &con);
198 if (con.iv && con.iv->ivlen != ivsize)
203 if (!ctx->more && ctx->used)
209 memcpy(ctx->iv, con.iv->iv, ivsize);
211 ctx->aead_assoclen = con.aead_assoclen;
215 unsigned long len = size;
216 struct scatterlist *sg = NULL;
218 /* use the existing memory in an allocated page */
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,
230 ctx->merge = (sg->offset + sg->length) &
239 if (!aead_writable(sk)) {
240 /* user space sent too much data */
246 /* allocate a new page */
247 len = min_t(unsigned long, size, aead_sndbuf(sk));
251 if (sgl->cur >= ALG_MAX_PAGES) {
257 sg = sgl->sg + sgl->cur;
258 plen = min_t(int, len, PAGE_SIZE);
260 sg_assign_page(sg, alloc_page(GFP_KERNEL));
265 err = memcpy_from_msg(page_address(sg_page(sg)),
268 __free_page(sg_page(sg));
269 sg_assign_page(sg, NULL);
280 ctx->merge = plen & (PAGE_SIZE - 1);
286 ctx->more = msg->msg_flags & MSG_MORE;
287 if (!ctx->more && !aead_sufficient_data(ctx)) {
293 aead_data_wakeup(sk);
296 return err ?: copied;
299 static ssize_t aead_sendpage(struct socket *sock, struct page *page,
300 int offset, size_t size, int flags)
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;
308 if (flags & MSG_SENDPAGE_NOTLAST)
311 if (sgl->cur >= ALG_MAX_PAGES)
315 if (!ctx->more && ctx->used)
321 if (!aead_writable(sk)) {
322 /* user space sent too much data */
331 sg_set_page(sgl->sg + sgl->cur, page, size, offset);
338 ctx->more = flags & MSG_MORE;
339 if (!ctx->more && !aead_sufficient_data(ctx)) {
345 aead_data_wakeup(sk);
351 static int aead_recvmsg(struct kiocb *unused, struct socket *sock,
352 struct msghdr *msg, size_t ignored, int flags)
354 struct sock *sk = sock->sk;
355 struct alg_sock *ask = alg_sk(sk);
356 struct aead_ctx *ctx = ask->private;
357 unsigned bs = crypto_aead_blocksize(crypto_aead_reqtfm(&ctx->aead_req));
358 unsigned as = crypto_aead_authsize(crypto_aead_reqtfm(&ctx->aead_req));
359 struct aead_sg_list *sgl = &ctx->tsgl;
360 struct scatterlist *sg = NULL;
361 struct scatterlist assoc[ALG_MAX_PAGES];
365 unsigned long used = 0;
367 size_t usedpages = 0;
368 unsigned int cnt = 0;
370 /* Limit number of IOV blocks to be accessed below */
371 if (msg->msg_iter.nr_segs > RSGL_MAX_ENTRIES)
377 * AEAD memory structure: For encryption, the tag is appended to the
378 * ciphertext which implies that the memory allocated for the ciphertext
379 * must be increased by the tag length. For decryption, the tag
380 * is expected to be concatenated to the ciphertext. The plaintext
381 * therefore has a memory size of the ciphertext minus the tag length.
383 * The memory structure for cipher operation has the following
385 * AEAD encryption input: assoc data || plaintext
386 * AEAD encryption output: cipherntext || auth tag
387 * AEAD decryption input: assoc data || ciphertext || auth tag
388 * AEAD decryption output: plaintext
392 err = aead_wait_for_data(sk, flags);
400 * Make sure sufficient data is present -- note, the same check is
401 * is also present in sendmsg/sendpage. The checks in sendpage/sendmsg
402 * shall provide an information to the data sender that something is
403 * wrong, but they are irrelevant to maintain the kernel integrity.
404 * We need this check here too in case user space decides to not honor
405 * the error message in sendmsg/sendpage and still call recvmsg. This
406 * check here protects the kernel integrity.
408 if (!aead_sufficient_data(ctx))
412 * The cipher operation input data is reduced by the associated data
413 * length as this data is processed separately later on.
415 used -= ctx->aead_assoclen;
418 /* round up output buffer to multiple of block size */
419 outlen = ((used + bs - 1) / bs * bs);
420 /* add the size needed for the auth tag to be created */
423 /* output data size is input without the authentication tag */
425 /* round up output buffer to multiple of block size */
426 outlen = ((outlen + bs - 1) / bs * bs);
429 /* convert iovecs of output buffers into scatterlists */
430 while (iov_iter_count(&msg->msg_iter)) {
431 size_t seglen = min_t(size_t, iov_iter_count(&msg->msg_iter),
432 (outlen - usedpages));
434 /* make one iovec available as scatterlist */
435 err = af_alg_make_sg(&ctx->rsgl[cnt], &msg->msg_iter,
440 /* chain the new scatterlist with initial list */
442 scatterwalk_crypto_chain(ctx->rsgl[0].sg,
443 ctx->rsgl[cnt].sg, 1,
444 sg_nents(ctx->rsgl[cnt-1].sg));
445 /* we do not need more iovecs as we have sufficient memory */
446 if (outlen <= usedpages)
448 iov_iter_advance(&msg->msg_iter, err);
453 /* ensure output buffer is sufficiently large */
454 if (usedpages < outlen)
457 sg_init_table(assoc, ALG_MAX_PAGES);
458 assoclen = ctx->aead_assoclen;
460 * Split scatterlist into two: first part becomes AD, second part
461 * is plaintext / ciphertext. The first part is assigned to assoc
462 * scatterlist. When this loop finishes, sg points to the start of the
463 * plaintext / ciphertext.
465 for (i = 0; i < ctx->tsgl.cur; i++) {
467 if (sg->length <= assoclen) {
468 /* AD is larger than one page */
469 sg_set_page(assoc + i, sg_page(sg),
470 sg->length, sg->offset);
471 assoclen -= sg->length;
472 if (i >= ctx->tsgl.cur)
474 } else if (!assoclen) {
475 /* current page is to start of plaintext / ciphertext */
477 /* AD terminates at page boundary */
478 sg_mark_end(assoc + i - 1);
480 /* AD size is zero */
484 /* AD does not terminate at page boundary */
485 sg_set_page(assoc + i, sg_page(sg),
486 assoclen, sg->offset);
487 sg_mark_end(assoc + i);
488 /* plaintext / ciphertext starts after AD */
489 sg->length -= assoclen;
490 sg->offset += assoclen;
495 aead_request_set_assoc(&ctx->aead_req, assoc, ctx->aead_assoclen);
496 aead_request_set_crypt(&ctx->aead_req, sg, ctx->rsgl[0].sg, used,
499 err = af_alg_wait_for_completion(ctx->enc ?
500 crypto_aead_encrypt(&ctx->aead_req) :
501 crypto_aead_decrypt(&ctx->aead_req),
505 /* EBADMSG implies a valid cipher operation took place */
516 for (i = 0; i < cnt; i++)
517 af_alg_free_sg(&ctx->rsgl[i]);
519 aead_wmem_wakeup(sk);
522 return err ? err : outlen;
525 static unsigned int aead_poll(struct file *file, struct socket *sock,
528 struct sock *sk = sock->sk;
529 struct alg_sock *ask = alg_sk(sk);
530 struct aead_ctx *ctx = ask->private;
533 sock_poll_wait(file, sk_sleep(sk), wait);
537 mask |= POLLIN | POLLRDNORM;
539 if (aead_writable(sk))
540 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
545 static struct proto_ops algif_aead_ops = {
548 .connect = sock_no_connect,
549 .socketpair = sock_no_socketpair,
550 .getname = sock_no_getname,
551 .ioctl = sock_no_ioctl,
552 .listen = sock_no_listen,
553 .shutdown = sock_no_shutdown,
554 .getsockopt = sock_no_getsockopt,
555 .mmap = sock_no_mmap,
556 .bind = sock_no_bind,
557 .accept = sock_no_accept,
558 .setsockopt = sock_no_setsockopt,
560 .release = af_alg_release,
561 .sendmsg = aead_sendmsg,
562 .sendpage = aead_sendpage,
563 .recvmsg = aead_recvmsg,
567 static void *aead_bind(const char *name, u32 type, u32 mask)
569 return crypto_alloc_aead(name, type, mask);
572 static void aead_release(void *private)
574 crypto_free_aead(private);
577 static int aead_setauthsize(void *private, unsigned int authsize)
579 return crypto_aead_setauthsize(private, authsize);
582 static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
584 return crypto_aead_setkey(private, key, keylen);
587 static void aead_sock_destruct(struct sock *sk)
589 struct alg_sock *ask = alg_sk(sk);
590 struct aead_ctx *ctx = ask->private;
591 unsigned int ivlen = crypto_aead_ivsize(
592 crypto_aead_reqtfm(&ctx->aead_req));
595 sock_kzfree_s(sk, ctx->iv, ivlen);
596 sock_kfree_s(sk, ctx, ctx->len);
597 af_alg_release_parent(sk);
600 static int aead_accept_parent(void *private, struct sock *sk)
602 struct aead_ctx *ctx;
603 struct alg_sock *ask = alg_sk(sk);
604 unsigned int len = sizeof(*ctx) + crypto_aead_reqsize(private);
605 unsigned int ivlen = crypto_aead_ivsize(private);
607 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
612 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
614 sock_kfree_s(sk, ctx, len);
617 memset(ctx->iv, 0, ivlen);
625 ctx->aead_assoclen = 0;
626 af_alg_init_completion(&ctx->completion);
627 sg_init_table(ctx->tsgl.sg, ALG_MAX_PAGES);
631 aead_request_set_tfm(&ctx->aead_req, private);
632 aead_request_set_callback(&ctx->aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
633 af_alg_complete, &ctx->completion);
635 sk->sk_destruct = aead_sock_destruct;
640 static const struct af_alg_type algif_type_aead = {
642 .release = aead_release,
643 .setkey = aead_setkey,
644 .setauthsize = aead_setauthsize,
645 .accept = aead_accept_parent,
646 .ops = &algif_aead_ops,
651 static int __init algif_aead_init(void)
653 return af_alg_register_type(&algif_type_aead);
656 static void __exit algif_aead_exit(void)
658 int err = af_alg_unregister_type(&algif_type_aead);
662 module_init(algif_aead_init);
663 module_exit(algif_aead_exit);
664 MODULE_LICENSE("GPL");
665 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
666 MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");