1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * algif_aead: User-space interface for AEAD algorithms
5 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
7 * This file provides the user-space API for AEAD ciphers.
9 * The following concept of the memory management is used:
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.
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.
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
26 #include <crypto/internal/aead.h>
27 #include <crypto/scatterwalk.h>
28 #include <crypto/if_alg.h>
29 #include <crypto/skcipher.h>
30 #include <crypto/null.h>
31 #include <linux/init.h>
32 #include <linux/list.h>
33 #include <linux/kernel.h>
35 #include <linux/module.h>
36 #include <linux/net.h>
40 struct crypto_aead *aead;
41 struct crypto_sync_skcipher *null_tfm;
44 static inline bool aead_sufficient_data(struct sock *sk)
46 struct alg_sock *ask = alg_sk(sk);
47 struct sock *psk = ask->parent;
48 struct alg_sock *pask = alg_sk(psk);
49 struct af_alg_ctx *ctx = ask->private;
50 struct aead_tfm *aeadc = pask->private;
51 struct crypto_aead *tfm = aeadc->aead;
52 unsigned int as = crypto_aead_authsize(tfm);
55 * The minimum amount of memory needed for an AEAD cipher is
56 * the AAD and in case of decryption the tag.
58 return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as);
61 static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
63 struct sock *sk = sock->sk;
64 struct alg_sock *ask = alg_sk(sk);
65 struct sock *psk = ask->parent;
66 struct alg_sock *pask = alg_sk(psk);
67 struct aead_tfm *aeadc = pask->private;
68 struct crypto_aead *tfm = aeadc->aead;
69 unsigned int ivsize = crypto_aead_ivsize(tfm);
71 return af_alg_sendmsg(sock, msg, size, ivsize);
74 static int crypto_aead_copy_sgl(struct crypto_sync_skcipher *null_tfm,
75 struct scatterlist *src,
76 struct scatterlist *dst, unsigned int len)
78 SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm);
80 skcipher_request_set_sync_tfm(skreq, null_tfm);
81 skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_SLEEP,
83 skcipher_request_set_crypt(skreq, src, dst, len, NULL);
85 return crypto_skcipher_encrypt(skreq);
88 static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
89 size_t ignored, int flags)
91 struct sock *sk = sock->sk;
92 struct alg_sock *ask = alg_sk(sk);
93 struct sock *psk = ask->parent;
94 struct alg_sock *pask = alg_sk(psk);
95 struct af_alg_ctx *ctx = ask->private;
96 struct aead_tfm *aeadc = pask->private;
97 struct crypto_aead *tfm = aeadc->aead;
98 struct crypto_sync_skcipher *null_tfm = aeadc->null_tfm;
99 unsigned int i, as = crypto_aead_authsize(tfm);
100 struct af_alg_async_req *areq;
101 struct af_alg_tsgl *tsgl, *tmp;
102 struct scatterlist *rsgl_src, *tsgl_src = NULL;
104 size_t used = 0; /* [in] TX bufs to be en/decrypted */
105 size_t outlen = 0; /* [out] RX bufs produced by kernel */
106 size_t usedpages = 0; /* [in] RX bufs to be used from user */
107 size_t processed = 0; /* [in] TX bufs to be consumed */
109 if (!ctx->init || ctx->more) {
110 err = af_alg_wait_for_data(sk, flags, 0);
116 * Data length provided by caller via sendmsg/sendpage that has not
117 * yet been processed.
122 * Make sure sufficient data is present -- note, the same check is
123 * also present in sendmsg/sendpage. The checks in sendpage/sendmsg
124 * shall provide an information to the data sender that something is
125 * wrong, but they are irrelevant to maintain the kernel integrity.
126 * We need this check here too in case user space decides to not honor
127 * the error message in sendmsg/sendpage and still call recvmsg. This
128 * check here protects the kernel integrity.
130 if (!aead_sufficient_data(sk))
134 * Calculate the minimum output buffer size holding the result of the
135 * cipher operation. When encrypting data, the receiving buffer is
136 * larger by the tag length compared to the input buffer as the
137 * encryption operation generates the tag. For decryption, the input
138 * buffer provides the tag which is consumed resulting in only the
139 * plaintext without a buffer for the tag returned to the caller.
147 * The cipher operation input data is reduced by the associated data
148 * length as this data is processed separately later on.
150 used -= ctx->aead_assoclen;
152 /* Allocate cipher request for current operation. */
153 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
154 crypto_aead_reqsize(tfm));
156 return PTR_ERR(areq);
158 /* convert iovecs of output buffers into RX SGL */
159 err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages);
164 * Ensure output buffer is sufficiently large. If the caller provides
165 * less buffer space, only use the relative required input size. This
166 * allows AIO operation where the caller sent all data to be processed
167 * and the AIO operation performs the operation on the different chunks
170 if (usedpages < outlen) {
171 size_t less = outlen - usedpages;
181 processed = used + ctx->aead_assoclen;
182 list_for_each_entry_safe(tsgl, tmp, &ctx->tsgl_list, list) {
183 for (i = 0; i < tsgl->cur; i++) {
184 struct scatterlist *process_sg = tsgl->sg + i;
186 if (!(process_sg->length) || !sg_page(process_sg))
188 tsgl_src = process_sg;
194 if (processed && !tsgl_src) {
200 * Copy of AAD from source to destination
202 * The AAD is copied to the destination buffer without change. Even
203 * when user space uses an in-place cipher operation, the kernel
204 * will copy the data as it does not see whether such in-place operation
207 * To ensure efficiency, the following implementation ensure that the
208 * ciphers are invoked to perform a crypto operation in-place. This
209 * is achieved by memory management specified as follows.
212 /* Use the RX SGL as source (and destination) for crypto op. */
213 rsgl_src = areq->first_rsgl.sgl.sg;
217 * Encryption operation - The in-place cipher operation is
218 * achieved by the following operation:
224 * RX SGL: AAD || PT || Tag
226 err = crypto_aead_copy_sgl(null_tfm, tsgl_src,
227 areq->first_rsgl.sgl.sg, processed);
230 af_alg_pull_tsgl(sk, processed, NULL, 0);
233 * Decryption operation - To achieve an in-place cipher
234 * operation, the following SGL structure is used:
236 * TX SGL: AAD || CT || Tag
238 * | copy | | Create SGL link.
240 * RX SGL: AAD || CT ----+
243 /* Copy AAD || CT to RX SGL buffer for in-place operation. */
244 err = crypto_aead_copy_sgl(null_tfm, tsgl_src,
245 areq->first_rsgl.sgl.sg, outlen);
249 /* Create TX SGL for tag and chain it to RX SGL. */
250 areq->tsgl_entries = af_alg_count_tsgl(sk, processed,
252 if (!areq->tsgl_entries)
253 areq->tsgl_entries = 1;
254 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
261 sg_init_table(areq->tsgl, areq->tsgl_entries);
263 /* Release TX SGL, except for tag data and reassign tag data. */
264 af_alg_pull_tsgl(sk, processed, areq->tsgl, processed - as);
266 /* chain the areq TX SGL holding the tag with RX SGL */
269 struct af_alg_sgl *sgl_prev = &areq->last_rsgl->sgl;
271 sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
272 sg_chain(sgl_prev->sg, sgl_prev->npages + 1,
275 /* no RX SGL present (e.g. authentication only) */
276 rsgl_src = areq->tsgl;
279 /* Initialize the crypto operation */
280 aead_request_set_crypt(&areq->cra_u.aead_req, rsgl_src,
281 areq->first_rsgl.sgl.sg, used, ctx->iv);
282 aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen);
283 aead_request_set_tfm(&areq->cra_u.aead_req, tfm);
285 if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
288 areq->iocb = msg->msg_iocb;
290 /* Remember output size that will be generated. */
291 areq->outlen = outlen;
293 aead_request_set_callback(&areq->cra_u.aead_req,
294 CRYPTO_TFM_REQ_MAY_SLEEP,
295 af_alg_async_cb, areq);
296 err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) :
297 crypto_aead_decrypt(&areq->cra_u.aead_req);
299 /* AIO operation in progress */
300 if (err == -EINPROGRESS)
305 /* Synchronous operation */
306 aead_request_set_callback(&areq->cra_u.aead_req,
307 CRYPTO_TFM_REQ_MAY_SLEEP |
308 CRYPTO_TFM_REQ_MAY_BACKLOG,
309 crypto_req_done, &ctx->wait);
310 err = crypto_wait_req(ctx->enc ?
311 crypto_aead_encrypt(&areq->cra_u.aead_req) :
312 crypto_aead_decrypt(&areq->cra_u.aead_req),
318 af_alg_free_resources(areq);
320 return err ? err : outlen;
323 static int aead_recvmsg(struct socket *sock, struct msghdr *msg,
324 size_t ignored, int flags)
326 struct sock *sk = sock->sk;
330 while (msg_data_left(msg)) {
331 int err = _aead_recvmsg(sock, msg, ignored, flags);
334 * This error covers -EIOCBQUEUED which implies that we can
335 * only handle one AIO request. If the caller wants to have
336 * multiple AIO requests in parallel, he must make multiple
337 * separate AIO calls.
339 * Also return the error if no data has been processed so far.
342 if (err == -EIOCBQUEUED || err == -EBADMSG || !ret)
351 af_alg_wmem_wakeup(sk);
356 static struct proto_ops algif_aead_ops = {
359 .connect = sock_no_connect,
360 .socketpair = sock_no_socketpair,
361 .getname = sock_no_getname,
362 .ioctl = sock_no_ioctl,
363 .listen = sock_no_listen,
364 .shutdown = sock_no_shutdown,
365 .mmap = sock_no_mmap,
366 .bind = sock_no_bind,
367 .accept = sock_no_accept,
369 .release = af_alg_release,
370 .sendmsg = aead_sendmsg,
371 .sendpage = af_alg_sendpage,
372 .recvmsg = aead_recvmsg,
376 static int aead_check_key(struct socket *sock)
380 struct alg_sock *pask;
381 struct aead_tfm *tfm;
382 struct sock *sk = sock->sk;
383 struct alg_sock *ask = alg_sk(sk);
386 if (!atomic_read(&ask->nokey_refcnt))
390 pask = alg_sk(ask->parent);
394 lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
395 if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY)
398 atomic_dec(&pask->nokey_refcnt);
399 atomic_set(&ask->nokey_refcnt, 0);
411 static int aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
416 err = aead_check_key(sock);
420 return aead_sendmsg(sock, msg, size);
423 static ssize_t aead_sendpage_nokey(struct socket *sock, struct page *page,
424 int offset, size_t size, int flags)
428 err = aead_check_key(sock);
432 return af_alg_sendpage(sock, page, offset, size, flags);
435 static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
436 size_t ignored, int flags)
440 err = aead_check_key(sock);
444 return aead_recvmsg(sock, msg, ignored, flags);
447 static struct proto_ops algif_aead_ops_nokey = {
450 .connect = sock_no_connect,
451 .socketpair = sock_no_socketpair,
452 .getname = sock_no_getname,
453 .ioctl = sock_no_ioctl,
454 .listen = sock_no_listen,
455 .shutdown = sock_no_shutdown,
456 .mmap = sock_no_mmap,
457 .bind = sock_no_bind,
458 .accept = sock_no_accept,
460 .release = af_alg_release,
461 .sendmsg = aead_sendmsg_nokey,
462 .sendpage = aead_sendpage_nokey,
463 .recvmsg = aead_recvmsg_nokey,
467 static void *aead_bind(const char *name, u32 type, u32 mask)
469 struct aead_tfm *tfm;
470 struct crypto_aead *aead;
471 struct crypto_sync_skcipher *null_tfm;
473 tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
475 return ERR_PTR(-ENOMEM);
477 aead = crypto_alloc_aead(name, type, mask);
480 return ERR_CAST(aead);
483 null_tfm = crypto_get_default_null_skcipher();
484 if (IS_ERR(null_tfm)) {
485 crypto_free_aead(aead);
487 return ERR_CAST(null_tfm);
491 tfm->null_tfm = null_tfm;
496 static void aead_release(void *private)
498 struct aead_tfm *tfm = private;
500 crypto_free_aead(tfm->aead);
501 crypto_put_default_null_skcipher();
505 static int aead_setauthsize(void *private, unsigned int authsize)
507 struct aead_tfm *tfm = private;
509 return crypto_aead_setauthsize(tfm->aead, authsize);
512 static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
514 struct aead_tfm *tfm = private;
516 return crypto_aead_setkey(tfm->aead, key, keylen);
519 static void aead_sock_destruct(struct sock *sk)
521 struct alg_sock *ask = alg_sk(sk);
522 struct af_alg_ctx *ctx = ask->private;
523 struct sock *psk = ask->parent;
524 struct alg_sock *pask = alg_sk(psk);
525 struct aead_tfm *aeadc = pask->private;
526 struct crypto_aead *tfm = aeadc->aead;
527 unsigned int ivlen = crypto_aead_ivsize(tfm);
529 af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
530 sock_kzfree_s(sk, ctx->iv, ivlen);
531 sock_kfree_s(sk, ctx, ctx->len);
532 af_alg_release_parent(sk);
535 static int aead_accept_parent_nokey(void *private, struct sock *sk)
537 struct af_alg_ctx *ctx;
538 struct alg_sock *ask = alg_sk(sk);
539 struct aead_tfm *tfm = private;
540 struct crypto_aead *aead = tfm->aead;
541 unsigned int len = sizeof(*ctx);
542 unsigned int ivlen = crypto_aead_ivsize(aead);
544 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
549 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
551 sock_kfree_s(sk, ctx, len);
554 memset(ctx->iv, 0, ivlen);
556 INIT_LIST_HEAD(&ctx->tsgl_list);
558 crypto_init_wait(&ctx->wait);
562 sk->sk_destruct = aead_sock_destruct;
567 static int aead_accept_parent(void *private, struct sock *sk)
569 struct aead_tfm *tfm = private;
571 if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY)
574 return aead_accept_parent_nokey(private, sk);
577 static const struct af_alg_type algif_type_aead = {
579 .release = aead_release,
580 .setkey = aead_setkey,
581 .setauthsize = aead_setauthsize,
582 .accept = aead_accept_parent,
583 .accept_nokey = aead_accept_parent_nokey,
584 .ops = &algif_aead_ops,
585 .ops_nokey = &algif_aead_ops_nokey,
590 static int __init algif_aead_init(void)
592 return af_alg_register_type(&algif_type_aead);
595 static void __exit algif_aead_exit(void)
597 int err = af_alg_unregister_type(&algif_type_aead);
601 module_init(algif_aead_init);
602 module_exit(algif_aead_exit);
603 MODULE_LICENSE("GPL");
604 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
605 MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");