1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * algif_aead: User-space interface for AEAD algorithms
4 *
5 * Copyright (C) 2014, Stephan Mueller <smueller@chronox.de>
6 *
7 * This file provides the user-space API for AEAD ciphers.
8 *
9 * The following concept of the memory management is used:
10 *
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 sendmsg (maybe with
13 * MSG_SPLICE_PAGES). Filling up the TX SGL does not cause a crypto operation
14 * -- the data will only be tracked by the kernel. Upon receipt of one recvmsg
15 * call, the caller must provide a buffer which is tracked with the RX SGL.
16 *
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.
20 *
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
23 * the RX SGL release.
24 */
25
26 #include <crypto/internal/aead.h>
27 #include <crypto/scatterwalk.h>
28 #include <crypto/if_alg.h>
29 #include <linux/init.h>
30 #include <linux/list.h>
31 #include <linux/kernel.h>
32 #include <linux/mm.h>
33 #include <linux/module.h>
34 #include <linux/net.h>
35 #include <net/sock.h>
36
aead_sufficient_data(struct sock * sk)37 static inline bool aead_sufficient_data(struct sock *sk)
38 {
39 struct alg_sock *ask = alg_sk(sk);
40 struct sock *psk = ask->parent;
41 struct alg_sock *pask = alg_sk(psk);
42 struct af_alg_ctx *ctx = ask->private;
43 struct crypto_aead *tfm = pask->private;
44 unsigned int as = crypto_aead_authsize(tfm);
45
46 /*
47 * The minimum amount of memory needed for an AEAD cipher is
48 * the AAD and in case of decryption the tag.
49 */
50 return ctx->used >= ctx->aead_assoclen + (ctx->enc ? 0 : as);
51 }
52
aead_sendmsg(struct socket * sock,struct msghdr * msg,size_t size)53 static int aead_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
54 {
55 struct sock *sk = sock->sk;
56 struct alg_sock *ask = alg_sk(sk);
57 struct sock *psk = ask->parent;
58 struct alg_sock *pask = alg_sk(psk);
59 struct crypto_aead *tfm = pask->private;
60 unsigned int ivsize = crypto_aead_ivsize(tfm);
61
62 return af_alg_sendmsg(sock, msg, size, ivsize);
63 }
64
_aead_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)65 static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
66 size_t ignored, int flags)
67 {
68 struct sock *sk = sock->sk;
69 struct alg_sock *ask = alg_sk(sk);
70 struct sock *psk = ask->parent;
71 struct alg_sock *pask = alg_sk(psk);
72 struct af_alg_ctx *ctx = ask->private;
73 struct crypto_aead *tfm = pask->private;
74 unsigned int as = crypto_aead_authsize(tfm);
75 struct af_alg_async_req *areq;
76 struct scatterlist *rsgl_src, *tsgl_src = NULL;
77 int err = 0;
78 size_t used = 0; /* [in] TX bufs to be en/decrypted */
79 size_t outlen = 0; /* [out] RX bufs produced by kernel */
80 size_t usedpages = 0; /* [in] RX bufs to be used from user */
81 size_t processed = 0; /* [in] TX bufs to be consumed */
82
83 if (!ctx->init || ctx->more) {
84 err = af_alg_wait_for_data(sk, flags, 0);
85 if (err)
86 return err;
87 }
88
89 /*
90 * Data length provided by caller via sendmsg that has not yet been
91 * processed.
92 */
93 used = ctx->used;
94
95 /*
96 * Make sure sufficient data is present -- note, the same check is also
97 * present in sendmsg. The checks in sendmsg shall provide an
98 * information to the data sender that something is wrong, but they are
99 * irrelevant to maintain the kernel integrity. We need this check
100 * here too in case user space decides to not honor the error message
101 * in sendmsg and still call recvmsg. This check here protects the
102 * kernel integrity.
103 */
104 if (!aead_sufficient_data(sk))
105 return -EINVAL;
106
107 /*
108 * Calculate the minimum output buffer size holding the result of the
109 * cipher operation. When encrypting data, the receiving buffer is
110 * larger by the tag length compared to the input buffer as the
111 * encryption operation generates the tag. For decryption, the input
112 * buffer provides the tag which is consumed resulting in only the
113 * plaintext without a buffer for the tag returned to the caller.
114 */
115 if (ctx->enc)
116 outlen = used + as;
117 else
118 outlen = used - as;
119
120 /*
121 * The cipher operation input data is reduced by the associated data
122 * length as this data is processed separately later on.
123 */
124 used -= ctx->aead_assoclen;
125
126 /* Allocate cipher request for current operation. */
127 areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
128 crypto_aead_reqsize(tfm));
129 if (IS_ERR(areq))
130 return PTR_ERR(areq);
131
132 /* convert iovecs of output buffers into RX SGL */
133 err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages);
134 if (err)
135 goto free;
136
137 /*
138 * Ensure output buffer is sufficiently large. If the caller provides
139 * less buffer space, only use the relative required input size. This
140 * allows AIO operation where the caller sent all data to be processed
141 * and the AIO operation performs the operation on the different chunks
142 * of the input data.
143 */
144 if (usedpages < outlen) {
145 size_t less = outlen - usedpages;
146
147 if (used < less) {
148 err = -EINVAL;
149 goto free;
150 }
151 used -= less;
152 outlen -= less;
153 }
154
155 /*
156 * Create a per request TX SGL for this request which tracks the
157 * SG entries from the global TX SGL.
158 */
159 processed = used + ctx->aead_assoclen;
160 areq->tsgl_entries = af_alg_count_tsgl(sk, processed);
161 if (!areq->tsgl_entries)
162 areq->tsgl_entries = 1;
163 areq->tsgl = sock_kmalloc(sk, array_size(sizeof(*areq->tsgl),
164 areq->tsgl_entries),
165 GFP_KERNEL);
166 if (!areq->tsgl) {
167 err = -ENOMEM;
168 goto free;
169 }
170 sg_init_table(areq->tsgl, areq->tsgl_entries);
171 af_alg_pull_tsgl(sk, processed, areq->tsgl);
172 tsgl_src = areq->tsgl;
173
174 /*
175 * Copy of AAD from source to destination
176 *
177 * The AAD is copied to the destination buffer without change. Even
178 * when user space uses an in-place cipher operation, the kernel
179 * will copy the data as it does not see whether such in-place operation
180 * is initiated.
181 */
182
183 /* Use the RX SGL as source (and destination) for crypto op. */
184 rsgl_src = areq->first_rsgl.sgl.sgt.sgl;
185
186 memcpy_sglist(rsgl_src, tsgl_src, ctx->aead_assoclen);
187
188 /* Initialize the crypto operation */
189 aead_request_set_crypt(&areq->cra_u.aead_req, tsgl_src,
190 areq->first_rsgl.sgl.sgt.sgl, used, ctx->iv);
191 aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen);
192 aead_request_set_tfm(&areq->cra_u.aead_req, tfm);
193
194 if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) {
195 /* AIO operation */
196 sock_hold(sk);
197 areq->iocb = msg->msg_iocb;
198
199 /* Remember output size that will be generated. */
200 areq->outlen = outlen;
201
202 aead_request_set_callback(&areq->cra_u.aead_req,
203 CRYPTO_TFM_REQ_MAY_SLEEP,
204 af_alg_async_cb, areq);
205 err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) :
206 crypto_aead_decrypt(&areq->cra_u.aead_req);
207
208 /* AIO operation in progress */
209 if (err == -EINPROGRESS)
210 return -EIOCBQUEUED;
211
212 sock_put(sk);
213 } else {
214 /* Synchronous operation */
215 aead_request_set_callback(&areq->cra_u.aead_req,
216 CRYPTO_TFM_REQ_MAY_SLEEP |
217 CRYPTO_TFM_REQ_MAY_BACKLOG,
218 crypto_req_done, &ctx->wait);
219 err = crypto_wait_req(ctx->enc ?
220 crypto_aead_encrypt(&areq->cra_u.aead_req) :
221 crypto_aead_decrypt(&areq->cra_u.aead_req),
222 &ctx->wait);
223 }
224
225
226 free:
227 af_alg_free_resources(areq);
228
229 return err ? err : outlen;
230 }
231
aead_recvmsg(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)232 static int aead_recvmsg(struct socket *sock, struct msghdr *msg,
233 size_t ignored, int flags)
234 {
235 struct sock *sk = sock->sk;
236 int ret = 0;
237
238 lock_sock(sk);
239 while (msg_data_left(msg)) {
240 int err = _aead_recvmsg(sock, msg, ignored, flags);
241
242 /*
243 * This error covers -EIOCBQUEUED which implies that we can
244 * only handle one AIO request. If the caller wants to have
245 * multiple AIO requests in parallel, he must make multiple
246 * separate AIO calls.
247 *
248 * Also return the error if no data has been processed so far.
249 */
250 if (err <= 0) {
251 if (err == -EIOCBQUEUED || err == -EBADMSG || !ret)
252 ret = err;
253 goto out;
254 }
255
256 ret += err;
257 }
258
259 out:
260 af_alg_wmem_wakeup(sk);
261 release_sock(sk);
262 return ret;
263 }
264
265 static struct proto_ops algif_aead_ops = {
266 .family = PF_ALG,
267
268 .connect = sock_no_connect,
269 .socketpair = sock_no_socketpair,
270 .getname = sock_no_getname,
271 .ioctl = sock_no_ioctl,
272 .listen = sock_no_listen,
273 .shutdown = sock_no_shutdown,
274 .mmap = sock_no_mmap,
275 .bind = sock_no_bind,
276 .accept = sock_no_accept,
277
278 .release = af_alg_release,
279 .sendmsg = aead_sendmsg,
280 .recvmsg = aead_recvmsg,
281 .poll = af_alg_poll,
282 };
283
aead_check_key(struct socket * sock)284 static int aead_check_key(struct socket *sock)
285 {
286 int err = 0;
287 struct sock *psk;
288 struct alg_sock *pask;
289 struct crypto_aead *tfm;
290 struct sock *sk = sock->sk;
291 struct alg_sock *ask = alg_sk(sk);
292
293 lock_sock(sk);
294 if (!atomic_read(&ask->nokey_refcnt))
295 goto unlock_child;
296
297 psk = ask->parent;
298 pask = alg_sk(ask->parent);
299 tfm = pask->private;
300
301 err = -ENOKEY;
302 lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
303 if (crypto_aead_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
304 goto unlock;
305
306 atomic_dec(&pask->nokey_refcnt);
307 atomic_set(&ask->nokey_refcnt, 0);
308
309 err = 0;
310
311 unlock:
312 release_sock(psk);
313 unlock_child:
314 release_sock(sk);
315
316 return err;
317 }
318
aead_sendmsg_nokey(struct socket * sock,struct msghdr * msg,size_t size)319 static int aead_sendmsg_nokey(struct socket *sock, struct msghdr *msg,
320 size_t size)
321 {
322 int err;
323
324 err = aead_check_key(sock);
325 if (err)
326 return err;
327
328 return aead_sendmsg(sock, msg, size);
329 }
330
aead_recvmsg_nokey(struct socket * sock,struct msghdr * msg,size_t ignored,int flags)331 static int aead_recvmsg_nokey(struct socket *sock, struct msghdr *msg,
332 size_t ignored, int flags)
333 {
334 int err;
335
336 err = aead_check_key(sock);
337 if (err)
338 return err;
339
340 return aead_recvmsg(sock, msg, ignored, flags);
341 }
342
343 static struct proto_ops algif_aead_ops_nokey = {
344 .family = PF_ALG,
345
346 .connect = sock_no_connect,
347 .socketpair = sock_no_socketpair,
348 .getname = sock_no_getname,
349 .ioctl = sock_no_ioctl,
350 .listen = sock_no_listen,
351 .shutdown = sock_no_shutdown,
352 .mmap = sock_no_mmap,
353 .bind = sock_no_bind,
354 .accept = sock_no_accept,
355
356 .release = af_alg_release,
357 .sendmsg = aead_sendmsg_nokey,
358 .recvmsg = aead_recvmsg_nokey,
359 .poll = af_alg_poll,
360 };
361
aead_bind(const char * name,u32 type,u32 mask)362 static void *aead_bind(const char *name, u32 type, u32 mask)
363 {
364 return crypto_alloc_aead(name, type, mask);
365 }
366
aead_release(void * private)367 static void aead_release(void *private)
368 {
369 crypto_free_aead(private);
370 }
371
aead_setauthsize(void * private,unsigned int authsize)372 static int aead_setauthsize(void *private, unsigned int authsize)
373 {
374 return crypto_aead_setauthsize(private, authsize);
375 }
376
aead_setkey(void * private,const u8 * key,unsigned int keylen)377 static int aead_setkey(void *private, const u8 *key, unsigned int keylen)
378 {
379 return crypto_aead_setkey(private, key, keylen);
380 }
381
aead_sock_destruct(struct sock * sk)382 static void aead_sock_destruct(struct sock *sk)
383 {
384 struct alg_sock *ask = alg_sk(sk);
385 struct af_alg_ctx *ctx = ask->private;
386 struct sock *psk = ask->parent;
387 struct alg_sock *pask = alg_sk(psk);
388 struct crypto_aead *tfm = pask->private;
389 unsigned int ivlen = crypto_aead_ivsize(tfm);
390
391 af_alg_pull_tsgl(sk, ctx->used, NULL);
392 sock_kzfree_s(sk, ctx->iv, ivlen);
393 sock_kfree_s(sk, ctx, ctx->len);
394 af_alg_release_parent(sk);
395 }
396
aead_accept_parent_nokey(void * private,struct sock * sk)397 static int aead_accept_parent_nokey(void *private, struct sock *sk)
398 {
399 struct af_alg_ctx *ctx;
400 struct alg_sock *ask = alg_sk(sk);
401 struct crypto_aead *tfm = private;
402 unsigned int len = sizeof(*ctx);
403 unsigned int ivlen = crypto_aead_ivsize(tfm);
404
405 ctx = sock_kmalloc(sk, len, GFP_KERNEL);
406 if (!ctx)
407 return -ENOMEM;
408 memset(ctx, 0, len);
409
410 ctx->iv = sock_kmalloc(sk, ivlen, GFP_KERNEL);
411 if (!ctx->iv) {
412 sock_kfree_s(sk, ctx, len);
413 return -ENOMEM;
414 }
415 memset(ctx->iv, 0, ivlen);
416
417 INIT_LIST_HEAD(&ctx->tsgl_list);
418 ctx->len = len;
419 crypto_init_wait(&ctx->wait);
420
421 ask->private = ctx;
422
423 sk->sk_destruct = aead_sock_destruct;
424
425 return 0;
426 }
427
aead_accept_parent(void * private,struct sock * sk)428 static int aead_accept_parent(void *private, struct sock *sk)
429 {
430 struct crypto_aead *tfm = private;
431
432 if (crypto_aead_get_flags(tfm) & CRYPTO_TFM_NEED_KEY)
433 return -ENOKEY;
434
435 return aead_accept_parent_nokey(private, sk);
436 }
437
438 static const struct af_alg_type algif_type_aead = {
439 .bind = aead_bind,
440 .release = aead_release,
441 .setkey = aead_setkey,
442 .setauthsize = aead_setauthsize,
443 .accept = aead_accept_parent,
444 .accept_nokey = aead_accept_parent_nokey,
445 .ops = &algif_aead_ops,
446 .ops_nokey = &algif_aead_ops_nokey,
447 .name = "aead",
448 .owner = THIS_MODULE
449 };
450
algif_aead_init(void)451 static int __init algif_aead_init(void)
452 {
453 return af_alg_register_type(&algif_type_aead);
454 }
455
algif_aead_exit(void)456 static void __exit algif_aead_exit(void)
457 {
458 int err = af_alg_unregister_type(&algif_type_aead);
459 BUG_ON(err);
460 }
461
462 module_init(algif_aead_init);
463 module_exit(algif_aead_exit);
464 MODULE_LICENSE("GPL");
465 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
466 MODULE_DESCRIPTION("AEAD kernel crypto API user space interface");
467