Root/crypto/algif_skcipher.c

1/*
2 * algif_skcipher: User-space interface for skcipher algorithms
3 *
4 * This file provides the user-space API for symmetric key ciphers.
5 *
6 * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 *
13 */
14
15#include <crypto/scatterwalk.h>
16#include <crypto/skcipher.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 skcipher_sg_list {
27    struct list_head list;
28
29    int cur;
30
31    struct scatterlist sg[0];
32};
33
34struct skcipher_ctx {
35    struct list_head tsgl;
36    struct af_alg_sgl rsgl;
37
38    void *iv;
39
40    struct af_alg_completion completion;
41
42    unsigned used;
43
44    unsigned int len;
45    bool more;
46    bool merge;
47    bool enc;
48
49    struct ablkcipher_request req;
50};
51
52#define MAX_SGL_ENTS ((PAGE_SIZE - sizeof(struct skcipher_sg_list)) / \
53              sizeof(struct scatterlist) - 1)
54
55static inline int skcipher_sndbuf(struct sock *sk)
56{
57    struct alg_sock *ask = alg_sk(sk);
58    struct skcipher_ctx *ctx = ask->private;
59
60    return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
61              ctx->used, 0);
62}
63
64static inline bool skcipher_writable(struct sock *sk)
65{
66    return PAGE_SIZE <= skcipher_sndbuf(sk);
67}
68
69static int skcipher_alloc_sgl(struct sock *sk)
70{
71    struct alg_sock *ask = alg_sk(sk);
72    struct skcipher_ctx *ctx = ask->private;
73    struct skcipher_sg_list *sgl;
74    struct scatterlist *sg = NULL;
75
76    sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
77    if (!list_empty(&ctx->tsgl))
78        sg = sgl->sg;
79
80    if (!sg || sgl->cur >= MAX_SGL_ENTS) {
81        sgl = sock_kmalloc(sk, sizeof(*sgl) +
82                       sizeof(sgl->sg[0]) * (MAX_SGL_ENTS + 1),
83                   GFP_KERNEL);
84        if (!sgl)
85            return -ENOMEM;
86
87        sg_init_table(sgl->sg, MAX_SGL_ENTS + 1);
88        sgl->cur = 0;
89
90        if (sg)
91            scatterwalk_sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);
92
93        list_add_tail(&sgl->list, &ctx->tsgl);
94    }
95
96    return 0;
97}
98
99static void skcipher_pull_sgl(struct sock *sk, int used)
100{
101    struct alg_sock *ask = alg_sk(sk);
102    struct skcipher_ctx *ctx = ask->private;
103    struct skcipher_sg_list *sgl;
104    struct scatterlist *sg;
105    int i;
106
107    while (!list_empty(&ctx->tsgl)) {
108        sgl = list_first_entry(&ctx->tsgl, struct skcipher_sg_list,
109                       list);
110        sg = sgl->sg;
111
112        for (i = 0; i < sgl->cur; i++) {
113            int plen = min_t(int, used, sg[i].length);
114
115            if (!sg_page(sg + i))
116                continue;
117
118            sg[i].length -= plen;
119            sg[i].offset += plen;
120
121            used -= plen;
122            ctx->used -= plen;
123
124            if (sg[i].length)
125                return;
126
127            put_page(sg_page(sg + i));
128            sg_assign_page(sg + i, NULL);
129        }
130
131        list_del(&sgl->list);
132        sock_kfree_s(sk, sgl,
133                 sizeof(*sgl) + sizeof(sgl->sg[0]) *
134                        (MAX_SGL_ENTS + 1));
135    }
136
137    if (!ctx->used)
138        ctx->merge = 0;
139}
140
141static void skcipher_free_sgl(struct sock *sk)
142{
143    struct alg_sock *ask = alg_sk(sk);
144    struct skcipher_ctx *ctx = ask->private;
145
146    skcipher_pull_sgl(sk, ctx->used);
147}
148
149static int skcipher_wait_for_wmem(struct sock *sk, unsigned flags)
150{
151    long timeout;
152    DEFINE_WAIT(wait);
153    int err = -ERESTARTSYS;
154
155    if (flags & MSG_DONTWAIT)
156        return -EAGAIN;
157
158    set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
159
160    for (;;) {
161        if (signal_pending(current))
162            break;
163        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
164        timeout = MAX_SCHEDULE_TIMEOUT;
165        if (sk_wait_event(sk, &timeout, skcipher_writable(sk))) {
166            err = 0;
167            break;
168        }
169    }
170    finish_wait(sk_sleep(sk), &wait);
171
172    return err;
173}
174
175static void skcipher_wmem_wakeup(struct sock *sk)
176{
177    struct socket_wq *wq;
178
179    if (!skcipher_writable(sk))
180        return;
181
182    rcu_read_lock();
183    wq = rcu_dereference(sk->sk_wq);
184    if (wq_has_sleeper(wq))
185        wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
186                               POLLRDNORM |
187                               POLLRDBAND);
188    sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
189    rcu_read_unlock();
190}
191
192static int skcipher_wait_for_data(struct sock *sk, unsigned flags)
193{
194    struct alg_sock *ask = alg_sk(sk);
195    struct skcipher_ctx *ctx = ask->private;
196    long timeout;
197    DEFINE_WAIT(wait);
198    int err = -ERESTARTSYS;
199
200    if (flags & MSG_DONTWAIT) {
201        return -EAGAIN;
202    }
203
204    set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
205
206    for (;;) {
207        if (signal_pending(current))
208            break;
209        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
210        timeout = MAX_SCHEDULE_TIMEOUT;
211        if (sk_wait_event(sk, &timeout, ctx->used)) {
212            err = 0;
213            break;
214        }
215    }
216    finish_wait(sk_sleep(sk), &wait);
217
218    clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
219
220    return err;
221}
222
223static void skcipher_data_wakeup(struct sock *sk)
224{
225    struct alg_sock *ask = alg_sk(sk);
226    struct skcipher_ctx *ctx = ask->private;
227    struct socket_wq *wq;
228
229    if (!ctx->used)
230        return;
231
232    rcu_read_lock();
233    wq = rcu_dereference(sk->sk_wq);
234    if (wq_has_sleeper(wq))
235        wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
236                               POLLRDNORM |
237                               POLLRDBAND);
238    sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
239    rcu_read_unlock();
240}
241
242static int skcipher_sendmsg(struct kiocb *unused, struct socket *sock,
243                struct msghdr *msg, size_t size)
244{
245    struct sock *sk = sock->sk;
246    struct alg_sock *ask = alg_sk(sk);
247    struct skcipher_ctx *ctx = ask->private;
248    struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req);
249    unsigned ivsize = crypto_ablkcipher_ivsize(tfm);
250    struct skcipher_sg_list *sgl;
251    struct af_alg_control con = {};
252    long copied = 0;
253    bool enc = 0;
254    int err;
255    int i;
256
257    if (msg->msg_controllen) {
258        err = af_alg_cmsg_send(msg, &con);
259        if (err)
260            return err;
261
262        switch (con.op) {
263        case ALG_OP_ENCRYPT:
264            enc = 1;
265            break;
266        case ALG_OP_DECRYPT:
267            enc = 0;
268            break;
269        default:
270            return -EINVAL;
271        }
272
273        if (con.iv && con.iv->ivlen != ivsize)
274            return -EINVAL;
275    }
276
277    err = -EINVAL;
278
279    lock_sock(sk);
280    if (!ctx->more && ctx->used)
281        goto unlock;
282
283    if (!ctx->used) {
284        ctx->enc = enc;
285        if (con.iv)
286            memcpy(ctx->iv, con.iv->iv, ivsize);
287    }
288
289    while (size) {
290        struct scatterlist *sg;
291        unsigned long len = size;
292        int plen;
293
294        if (ctx->merge) {
295            sgl = list_entry(ctx->tsgl.prev,
296                     struct skcipher_sg_list, list);
297            sg = sgl->sg + sgl->cur - 1;
298            len = min_t(unsigned long, len,
299                    PAGE_SIZE - sg->offset - sg->length);
300
301            err = memcpy_fromiovec(page_address(sg_page(sg)) +
302                           sg->offset + sg->length,
303                           msg->msg_iov, len);
304            if (err)
305                goto unlock;
306
307            sg->length += len;
308            ctx->merge = (sg->offset + sg->length) &
309                     (PAGE_SIZE - 1);
310
311            ctx->used += len;
312            copied += len;
313            size -= len;
314            continue;
315        }
316
317        if (!skcipher_writable(sk)) {
318            err = skcipher_wait_for_wmem(sk, msg->msg_flags);
319            if (err)
320                goto unlock;
321        }
322
323        len = min_t(unsigned long, len, skcipher_sndbuf(sk));
324
325        err = skcipher_alloc_sgl(sk);
326        if (err)
327            goto unlock;
328
329        sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
330        sg = sgl->sg;
331        do {
332            i = sgl->cur;
333            plen = min_t(int, len, PAGE_SIZE);
334
335            sg_assign_page(sg + i, alloc_page(GFP_KERNEL));
336            err = -ENOMEM;
337            if (!sg_page(sg + i))
338                goto unlock;
339
340            err = memcpy_fromiovec(page_address(sg_page(sg + i)),
341                           msg->msg_iov, plen);
342            if (err) {
343                __free_page(sg_page(sg + i));
344                sg_assign_page(sg + i, NULL);
345                goto unlock;
346            }
347
348            sg[i].length = plen;
349            len -= plen;
350            ctx->used += plen;
351            copied += plen;
352            size -= plen;
353            sgl->cur++;
354        } while (len && sgl->cur < MAX_SGL_ENTS);
355
356        ctx->merge = plen & (PAGE_SIZE - 1);
357    }
358
359    err = 0;
360
361    ctx->more = msg->msg_flags & MSG_MORE;
362    if (!ctx->more && !list_empty(&ctx->tsgl))
363        sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
364
365unlock:
366    skcipher_data_wakeup(sk);
367    release_sock(sk);
368
369    return copied ?: err;
370}
371
372static ssize_t skcipher_sendpage(struct socket *sock, struct page *page,
373                 int offset, size_t size, int flags)
374{
375    struct sock *sk = sock->sk;
376    struct alg_sock *ask = alg_sk(sk);
377    struct skcipher_ctx *ctx = ask->private;
378    struct skcipher_sg_list *sgl;
379    int err = -EINVAL;
380
381    lock_sock(sk);
382    if (!ctx->more && ctx->used)
383        goto unlock;
384
385    if (!size)
386        goto done;
387
388    if (!skcipher_writable(sk)) {
389        err = skcipher_wait_for_wmem(sk, flags);
390        if (err)
391            goto unlock;
392    }
393
394    err = skcipher_alloc_sgl(sk);
395    if (err)
396        goto unlock;
397
398    ctx->merge = 0;
399    sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
400
401    get_page(page);
402    sg_set_page(sgl->sg + sgl->cur, page, size, offset);
403    sgl->cur++;
404    ctx->used += size;
405
406done:
407    ctx->more = flags & MSG_MORE;
408    if (!ctx->more && !list_empty(&ctx->tsgl))
409        sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
410
411unlock:
412    skcipher_data_wakeup(sk);
413    release_sock(sk);
414
415    return err ?: size;
416}
417
418static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
419                struct msghdr *msg, size_t ignored, int flags)
420{
421    struct sock *sk = sock->sk;
422    struct alg_sock *ask = alg_sk(sk);
423    struct skcipher_ctx *ctx = ask->private;
424    unsigned bs = crypto_ablkcipher_blocksize(crypto_ablkcipher_reqtfm(
425        &ctx->req));
426    struct skcipher_sg_list *sgl;
427    struct scatterlist *sg;
428    unsigned long iovlen;
429    struct iovec *iov;
430    int err = -EAGAIN;
431    int used;
432    long copied = 0;
433
434    lock_sock(sk);
435    for (iov = msg->msg_iov, iovlen = msg->msg_iovlen; iovlen > 0;
436         iovlen--, iov++) {
437        unsigned long seglen = iov->iov_len;
438        char __user *from = iov->iov_base;
439
440        while (seglen) {
441            sgl = list_first_entry(&ctx->tsgl,
442                           struct skcipher_sg_list, list);
443            sg = sgl->sg;
444
445            while (!sg->length)
446                sg++;
447
448            used = ctx->used;
449            if (!used) {
450                err = skcipher_wait_for_data(sk, flags);
451                if (err)
452                    goto unlock;
453            }
454
455            used = min_t(unsigned long, used, seglen);
456
457            used = af_alg_make_sg(&ctx->rsgl, from, used, 1);
458            err = used;
459            if (err < 0)
460                goto unlock;
461
462            if (ctx->more || used < ctx->used)
463                used -= used % bs;
464
465            err = -EINVAL;
466            if (!used)
467                goto free;
468
469            ablkcipher_request_set_crypt(&ctx->req, sg,
470                             ctx->rsgl.sg, used,
471                             ctx->iv);
472
473            err = af_alg_wait_for_completion(
474                ctx->enc ?
475                    crypto_ablkcipher_encrypt(&ctx->req) :
476                    crypto_ablkcipher_decrypt(&ctx->req),
477                &ctx->completion);
478
479free:
480            af_alg_free_sg(&ctx->rsgl);
481
482            if (err)
483                goto unlock;
484
485            copied += used;
486            from += used;
487            seglen -= used;
488            skcipher_pull_sgl(sk, used);
489        }
490    }
491
492    err = 0;
493
494unlock:
495    skcipher_wmem_wakeup(sk);
496    release_sock(sk);
497
498    return copied ?: err;
499}
500
501
502static unsigned int skcipher_poll(struct file *file, struct socket *sock,
503                  poll_table *wait)
504{
505    struct sock *sk = sock->sk;
506    struct alg_sock *ask = alg_sk(sk);
507    struct skcipher_ctx *ctx = ask->private;
508    unsigned int mask;
509
510    sock_poll_wait(file, sk_sleep(sk), wait);
511    mask = 0;
512
513    if (ctx->used)
514        mask |= POLLIN | POLLRDNORM;
515
516    if (skcipher_writable(sk))
517        mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
518
519    return mask;
520}
521
522static struct proto_ops algif_skcipher_ops = {
523    .family = PF_ALG,
524
525    .connect = sock_no_connect,
526    .socketpair = sock_no_socketpair,
527    .getname = sock_no_getname,
528    .ioctl = sock_no_ioctl,
529    .listen = sock_no_listen,
530    .shutdown = sock_no_shutdown,
531    .getsockopt = sock_no_getsockopt,
532    .mmap = sock_no_mmap,
533    .bind = sock_no_bind,
534    .accept = sock_no_accept,
535    .setsockopt = sock_no_setsockopt,
536
537    .release = af_alg_release,
538    .sendmsg = skcipher_sendmsg,
539    .sendpage = skcipher_sendpage,
540    .recvmsg = skcipher_recvmsg,
541    .poll = skcipher_poll,
542};
543
544static void *skcipher_bind(const char *name, u32 type, u32 mask)
545{
546    return crypto_alloc_ablkcipher(name, type, mask);
547}
548
549static void skcipher_release(void *private)
550{
551    crypto_free_ablkcipher(private);
552}
553
554static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
555{
556    return crypto_ablkcipher_setkey(private, key, keylen);
557}
558
559static void skcipher_sock_destruct(struct sock *sk)
560{
561    struct alg_sock *ask = alg_sk(sk);
562    struct skcipher_ctx *ctx = ask->private;
563    struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(&ctx->req);
564
565    skcipher_free_sgl(sk);
566    sock_kfree_s(sk, ctx->iv, crypto_ablkcipher_ivsize(tfm));
567    sock_kfree_s(sk, ctx, ctx->len);
568    af_alg_release_parent(sk);
569}
570
571static int skcipher_accept_parent(void *private, struct sock *sk)
572{
573    struct skcipher_ctx *ctx;
574    struct alg_sock *ask = alg_sk(sk);
575    unsigned int len = sizeof(*ctx) + crypto_ablkcipher_reqsize(private);
576
577    ctx = sock_kmalloc(sk, len, GFP_KERNEL);
578    if (!ctx)
579        return -ENOMEM;
580
581    ctx->iv = sock_kmalloc(sk, crypto_ablkcipher_ivsize(private),
582                   GFP_KERNEL);
583    if (!ctx->iv) {
584        sock_kfree_s(sk, ctx, len);
585        return -ENOMEM;
586    }
587
588    memset(ctx->iv, 0, crypto_ablkcipher_ivsize(private));
589
590    INIT_LIST_HEAD(&ctx->tsgl);
591    ctx->len = len;
592    ctx->used = 0;
593    ctx->more = 0;
594    ctx->merge = 0;
595    ctx->enc = 0;
596    af_alg_init_completion(&ctx->completion);
597
598    ask->private = ctx;
599
600    ablkcipher_request_set_tfm(&ctx->req, private);
601    ablkcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
602                    af_alg_complete, &ctx->completion);
603
604    sk->sk_destruct = skcipher_sock_destruct;
605
606    return 0;
607}
608
609static const struct af_alg_type algif_type_skcipher = {
610    .bind = skcipher_bind,
611    .release = skcipher_release,
612    .setkey = skcipher_setkey,
613    .accept = skcipher_accept_parent,
614    .ops = &algif_skcipher_ops,
615    .name = "skcipher",
616    .owner = THIS_MODULE
617};
618
619static int __init algif_skcipher_init(void)
620{
621    return af_alg_register_type(&algif_type_skcipher);
622}
623
624static void __exit algif_skcipher_exit(void)
625{
626    int err = af_alg_unregister_type(&algif_type_skcipher);
627    BUG_ON(err);
628}
629
630module_init(algif_skcipher_init);
631module_exit(algif_skcipher_exit);
632MODULE_LICENSE("GPL");
633

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