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->op ? 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 inline int aead_cipher_op(struct af_alg_ctx *ctx,
75 struct af_alg_async_req *areq)
79 return crypto_aead_encrypt(&areq->cra_u.aead_req);
81 return crypto_aead_decrypt(&areq->cra_u.aead_req);
87 static int crypto_aead_copy_sgl(struct crypto_sync_skcipher *null_tfm,
88 struct scatterlist *src,
89 struct scatterlist *dst, unsigned int len)
91 SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, null_tfm);
93 skcipher_request_set_sync_tfm(skreq, null_tfm);
94 skcipher_request_set_callback(skreq, CRYPTO_TFM_REQ_MAY_SLEEP,
96 skcipher_request_set_crypt(skreq, src, dst, len, NULL);
98 return crypto_skcipher_encrypt(skreq);
101 static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
102 size_t ignored, int flags)
104 struct sock *sk = sock->sk;
105 struct alg_sock *ask = alg_sk(sk);
106 struct sock *psk = ask->parent;
107 struct alg_sock *pask = alg_sk(psk);
108 struct af_alg_ctx *ctx = ask->private;
109 struct aead_tfm *aeadc = pask->private;
110 struct crypto_aead *tfm = aeadc->aead;
111 struct crypto_sync_skcipher *null_tfm = aeadc->null_tfm;
112 unsigned int i, as = crypto_aead_authsize(tfm);
113 struct af_alg_async_req *areq;
114 struct af_alg_tsgl *tsgl, *tmp;
115 struct scatterlist *rsgl_src, *tsgl_src = NULL;
117 size_t used = 0; /* [in] TX bufs to be en/decrypted */
118 size_t outlen = 0; /* [out] RX bufs produced by kernel */
119 size_t usedpages = 0; /* [in] RX bufs to be used from user */
120 size_t processed = 0; /* [in] TX bufs to be consumed */
122 if (!ctx->init || ctx->more) {
123 err = af_alg_wait_for_data(sk, flags, 0);
129 * Data length provided by caller via sendmsg/sendpage that has not
130 * yet been processed.
135 * Make sure sufficient data is present -- note, the same check is
136 * also present in sendmsg/sendpage. The checks in sendpage/sendmsg
137 * shall provide an information to the data sender that something is
138 * wrong, but they are irrelevant to maintain the kernel integrity.
139 * We need this check here too in case user space decides to not honor
140 * the error message in sendmsg/sendpage and still call recvmsg. This
141 * check here protects the kernel integrity.
143 if (!aead_sufficient_data(sk))
147 * Calculate the minimum output buffer size holding the result of the
148 * cipher operation. When encrypting data, the receiving buffer is
149 * larger by the tag length compared to the input buffer as the
150 * encryption operation generates the tag. For decryption, the input
151 * buffer provides the tag which is consumed resulting in only the
152 * plaintext without a buffer for the tag returned to the caller.
160 * The cipher operation input data is reduced by the associated data
161 * length as this data is processed separately later on.
163 used -= ctx->aead_assoclen;
165 /* Allocate cipher request for current operation. */
166 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
167 crypto_aead_reqsize(tfm));
169 return PTR_ERR(areq);
171 /* convert iovecs of output buffers into RX SGL */
172 err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages);
177 * Ensure output buffer is sufficiently large. If the caller provides
178 * less buffer space, only use the relative required input size. This
179 * allows AIO operation where the caller sent all data to be processed
180 * and the AIO operation performs the operation on the different chunks
183 if (usedpages < outlen) {
184 size_t less = outlen - usedpages;
194 processed = used + ctx->aead_assoclen;
195 list_for_each_entry_safe(tsgl, tmp, &ctx->tsgl_list, list) {
196 for (i = 0; i < tsgl->cur; i++) {
197 struct scatterlist *process_sg = tsgl->sg + i;
199 if (!(process_sg->length) || !sg_page(process_sg))
201 tsgl_src = process_sg;
207 if (processed && !tsgl_src) {
213 * Copy of AAD from source to destination
215 * The AAD is copied to the destination buffer without change. Even
216 * when user space uses an in-place cipher operation, the kernel
217 * will copy the data as it does not see whether such in-place operation
220 * To ensure efficiency, the following implementation ensure that the
221 * ciphers are invoked to perform a crypto operation in-place. This
222 * is achieved by memory management specified as follows.
225 /* Use the RX SGL as source (and destination) for crypto op. */
226 rsgl_src = areq->first_rsgl.sgl.sg;
228 if (ctx->op == ALG_OP_ENCRYPT) {
230 * Encryption operation - The in-place cipher operation is
231 * achieved by the following operation:
237 * RX SGL: AAD || PT || Tag
239 err = crypto_aead_copy_sgl(null_tfm, tsgl_src,
240 areq->first_rsgl.sgl.sg, processed);
243 af_alg_pull_tsgl(sk, processed, NULL, 0);
244 } else if (ctx->op == ALG_OP_DECRYPT) {
246 * Decryption operation - To achieve an in-place cipher
247 * operation, the following SGL structure is used:
249 * TX SGL: AAD || CT || Tag
251 * | copy | | Create SGL link.
253 * RX SGL: AAD || CT ----+
256 /* Copy AAD || CT to RX SGL buffer for in-place operation. */
257 err = crypto_aead_copy_sgl(null_tfm, tsgl_src,
258 areq->first_rsgl.sgl.sg, outlen);
262 /* Create TX SGL for tag and chain it to RX SGL. */
263 areq->tsgl_entries = af_alg_count_tsgl(sk, processed,
265 if (!areq->tsgl_entries)
266 areq->tsgl_entries = 1;
267 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
274 sg_init_table(areq->tsgl, areq->tsgl_entries);
276 /* Release TX SGL, except for tag data and reassign tag data. */
277 af_alg_pull_tsgl(sk, processed, areq->tsgl, processed - as);
279 /* chain the areq TX SGL holding the tag with RX SGL */
282 struct af_alg_sgl *sgl_prev = &areq->last_rsgl->sgl;
284 sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
285 sg_chain(sgl_prev->sg, sgl_prev->npages + 1,
288 /* no RX SGL present (e.g. authentication only) */
289 rsgl_src = areq->tsgl;
292 /* Initialize the crypto operation */
293 aead_request_set_crypt(&areq->cra_u.aead_req, rsgl_src,
294 areq->first_rsgl.sgl.sg, used, ctx->iv);
295 aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen);
296 aead_request_set_tfm(&areq->cra_u.aead_req, tfm);
298 if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
301 areq->iocb = msg->msg_iocb;
303 /* Remember output size that will be generated. */
304 areq->outlen = outlen;
306 aead_request_set_callback(&areq->cra_u.aead_req,
307 CRYPTO_TFM_REQ_MAY_SLEEP,
308 af_alg_async_cb, areq);
309 err = aead_cipher_op(ctx, areq);
311 /* AIO operation in progress */
312 if (err == -EINPROGRESS)
317 /* Synchronous operation */
318 aead_request_set_callback(&areq->cra_u.aead_req,
319 CRYPTO_TFM_REQ_MAY_SLEEP |
320 CRYPTO_TFM_REQ_MAY_BACKLOG,
321 crypto_req_done, &ctx->wait);
322 err = crypto_wait_req(aead_cipher_op(ctx, areq), &ctx->wait);
327 af_alg_free_resources(areq);
329 return err ? err : outlen;
332 static int aead_recvmsg(struct socket *sock, struct msghdr *msg,
333 size_t ignored, int flags)
335 struct sock *sk = sock->sk;
339 while (msg_data_left(msg)) {
340 int err = _aead_recvmsg(sock, msg, ignored, flags);
343 * This error covers -EIOCBQUEUED which implies that we can
344 * only handle one AIO request. If the caller wants to have
345 * multiple AIO requests in parallel, he must make multiple
346 * separate AIO calls.
348 * Also return the error if no data has been processed so far.
351 if (err == -EIOCBQUEUED || err == -EBADMSG || !ret)
360 af_alg_wmem_wakeup(sk);
365 static struct proto_ops algif_aead_ops = {
368 .connect = sock_no_connect,
369 .socketpair = sock_no_socketpair,
370 .getname = sock_no_getname,
371 .ioctl = sock_no_ioctl,
372 .listen = sock_no_listen,
373 .shutdown = sock_no_shutdown,
374 .mmap = sock_no_mmap,
375 .bind = sock_no_bind,
376 .accept = sock_no_accept,
378 .release = af_alg_release,
379 .sendmsg = aead_sendmsg,
380 .sendpage = af_alg_sendpage,
381 .recvmsg = aead_recvmsg,
385 static int aead_check_key(struct socket *sock)
389 struct alg_sock *pask;
390 struct aead_tfm *tfm;
391 struct sock *sk = sock->sk;
392 struct alg_sock *ask = alg_sk(sk);
395 if (!atomic_read(&ask->nokey_refcnt))
399 pask = alg_sk(ask->parent);
403 lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
404 if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY)
407 atomic_dec(&pask->nokey_refcnt);
408 atomic_set(&ask->nokey_refcnt, 0);
420 static int aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
425 err = aead_check_key(sock);
429 return aead_sendmsg(sock, msg, size);
432 static ssize_t aead_sendpage_nokey(struct socket *sock, struct page *page,
433 int offset, size_t size, int flags)
437 err = aead_check_key(sock);
441 return af_alg_sendpage(sock, page, offset, size, flags);
444 static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
445 size_t ignored, int flags)
449 err = aead_check_key(sock);
453 return aead_recvmsg(sock, msg, ignored, flags);
456 static struct proto_ops algif_aead_ops_nokey = {
459 .connect = sock_no_connect,
460 .socketpair = sock_no_socketpair,
461 .getname = sock_no_getname,
462 .ioctl = sock_no_ioctl,
463 .listen = sock_no_listen,
464 .shutdown = sock_no_shutdown,
465 .mmap = sock_no_mmap,
466 .bind = sock_no_bind,
467 .accept = sock_no_accept,
469 .release = af_alg_release,
470 .sendmsg = aead_sendmsg_nokey,
471 .sendpage = aead_sendpage_nokey,
472 .recvmsg = aead_recvmsg_nokey,
476 static void *aead_bind(const char *name, u32 type, u32 mask)
478 struct aead_tfm *tfm;
479 struct crypto_aead *aead;
480 struct crypto_sync_skcipher *null_tfm;
482 tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
484 return ERR_PTR(-ENOMEM);
486 aead = crypto_alloc_aead(name, type, mask);
489 return ERR_CAST(aead);
492 null_tfm = crypto_get_default_null_skcipher();
493 if (IS_ERR(null_tfm)) {
494 crypto_free_aead(aead);
496 return ERR_CAST(null_tfm);
500 tfm->null_tfm = null_tfm;
505 static void aead_release(void *private)
507 struct aead_tfm *tfm = private;
509 crypto_free_aead(tfm->aead);
510 crypto_put_default_null_skcipher();
514 static int aead_setauthsize(void *private, unsigned int authsize)
516 struct aead_tfm *tfm = private;
518 return crypto_aead_setauthsize(tfm->aead, authsize);
521 static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
523 struct aead_tfm *tfm = private;
525 return crypto_aead_setkey(tfm->aead, key, keylen);
528 static void aead_sock_destruct(struct sock *sk)
530 struct alg_sock *ask = alg_sk(sk);
531 struct af_alg_ctx *ctx = ask->private;
532 struct sock *psk = ask->parent;
533 struct alg_sock *pask = alg_sk(psk);
534 struct aead_tfm *aeadc = pask->private;
535 struct crypto_aead *tfm = aeadc->aead;
536 unsigned int ivlen = crypto_aead_ivsize(tfm);
538 af_alg_pull_tsgl(sk, ctx->used, NULL, 0);
539 sock_kzfree_s(sk, ctx->iv, ivlen);
540 sock_kfree_s(sk, ctx, ctx->len);
541 af_alg_release_parent(sk);
544 static int aead_accept_parent_nokey(void *private, struct sock *sk)
546 struct af_alg_ctx *ctx;
547 struct alg_sock *ask = alg_sk(sk);
548 struct aead_tfm *tfm = private;
549 struct crypto_aead *aead = tfm->aead;
550 unsigned int len = sizeof(*ctx);
551 unsigned int ivlen = crypto_aead_ivsize(aead);
553 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
558 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
560 sock_kfree_s(sk, ctx, len);
563 memset(ctx->iv, 0, ivlen);
565 INIT_LIST_HEAD(&ctx->tsgl_list);
567 crypto_init_wait(&ctx->wait);
571 sk->sk_destruct = aead_sock_destruct;
576 static int aead_accept_parent(void *private, struct sock *sk)
578 struct aead_tfm *tfm = private;
580 if (crypto_aead_get_flags(tfm->aead) & CRYPTO_TFM_NEED_KEY)
583 return aead_accept_parent_nokey(private, sk);
586 static const struct af_alg_type algif_type_aead = {
588 .release = aead_release,
589 .setkey = aead_setkey,
590 .setauthsize = aead_setauthsize,
591 .accept = aead_accept_parent,
592 .accept_nokey = aead_accept_parent_nokey,
593 .ops = &algif_aead_ops,
594 .ops_nokey = &algif_aead_ops_nokey,
599 static int __init algif_aead_init(void)
601 return af_alg_register_type(&algif_type_aead);
604 static void __exit algif_aead_exit(void)
606 int err = af_alg_unregister_type(&algif_type_aead);
610 module_init(algif_aead_init);
611 module_exit(algif_aead_exit);
612 MODULE_LICENSE("GPL");
613 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
614 MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");