Root/security/keys/encrypted.c

Source at commit be977234bfb4a6dca8a39e7c52165e4cd536ad71 created 9 years 5 months ago.
By Lars-Peter Clausen, jz4740: Fix compile error
1/*
2 * Copyright (C) 2010 IBM Corporation
3 *
4 * Author:
5 * Mimi Zohar <zohar@us.ibm.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, version 2 of the License.
10 *
11 * See Documentation/keys-trusted-encrypted.txt
12 */
13
14#include <linux/uaccess.h>
15#include <linux/module.h>
16#include <linux/init.h>
17#include <linux/slab.h>
18#include <linux/parser.h>
19#include <linux/string.h>
20#include <linux/err.h>
21#include <keys/user-type.h>
22#include <keys/trusted-type.h>
23#include <keys/encrypted-type.h>
24#include <linux/key-type.h>
25#include <linux/random.h>
26#include <linux/rcupdate.h>
27#include <linux/scatterlist.h>
28#include <linux/crypto.h>
29#include <crypto/hash.h>
30#include <crypto/sha.h>
31#include <crypto/aes.h>
32
33#include "encrypted.h"
34
35static const char KEY_TRUSTED_PREFIX[] = "trusted:";
36static const char KEY_USER_PREFIX[] = "user:";
37static const char hash_alg[] = "sha256";
38static const char hmac_alg[] = "hmac(sha256)";
39static const char blkcipher_alg[] = "cbc(aes)";
40static unsigned int ivsize;
41static int blksize;
42
43#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
44#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
45#define HASH_SIZE SHA256_DIGEST_SIZE
46#define MAX_DATA_SIZE 4096
47#define MIN_DATA_SIZE 20
48
49struct sdesc {
50    struct shash_desc shash;
51    char ctx[];
52};
53
54static struct crypto_shash *hashalg;
55static struct crypto_shash *hmacalg;
56
57enum {
58    Opt_err = -1, Opt_new, Opt_load, Opt_update
59};
60
61static const match_table_t key_tokens = {
62    {Opt_new, "new"},
63    {Opt_load, "load"},
64    {Opt_update, "update"},
65    {Opt_err, NULL}
66};
67
68static int aes_get_sizes(void)
69{
70    struct crypto_blkcipher *tfm;
71
72    tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
73    if (IS_ERR(tfm)) {
74        pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
75               PTR_ERR(tfm));
76        return PTR_ERR(tfm);
77    }
78    ivsize = crypto_blkcipher_ivsize(tfm);
79    blksize = crypto_blkcipher_blocksize(tfm);
80    crypto_free_blkcipher(tfm);
81    return 0;
82}
83
84/*
85 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
86 *
87 * key-type:= "trusted:" | "encrypted:"
88 * desc:= master-key description
89 *
90 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
91 * only the master key description is permitted to change, not the key-type.
92 * The key-type remains constant.
93 *
94 * On success returns 0, otherwise -EINVAL.
95 */
96static int valid_master_desc(const char *new_desc, const char *orig_desc)
97{
98    if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
99        if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
100            goto out;
101        if (orig_desc)
102            if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
103                goto out;
104    } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
105        if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
106            goto out;
107        if (orig_desc)
108            if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
109                goto out;
110    } else
111        goto out;
112    return 0;
113out:
114    return -EINVAL;
115}
116
117/*
118 * datablob_parse - parse the keyctl data
119 *
120 * datablob format:
121 * new <master-key name> <decrypted data length>
122 * load <master-key name> <decrypted data length> <encrypted iv + data>
123 * update <new-master-key name>
124 *
125 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
126 * which is null terminated.
127 *
128 * On success returns 0, otherwise -EINVAL.
129 */
130static int datablob_parse(char *datablob, char **master_desc,
131              char **decrypted_datalen, char **hex_encoded_iv)
132{
133    substring_t args[MAX_OPT_ARGS];
134    int ret = -EINVAL;
135    int key_cmd;
136    char *p;
137
138    p = strsep(&datablob, " \t");
139    if (!p)
140        return ret;
141    key_cmd = match_token(p, key_tokens, args);
142
143    *master_desc = strsep(&datablob, " \t");
144    if (!*master_desc)
145        goto out;
146
147    if (valid_master_desc(*master_desc, NULL) < 0)
148        goto out;
149
150    if (decrypted_datalen) {
151        *decrypted_datalen = strsep(&datablob, " \t");
152        if (!*decrypted_datalen)
153            goto out;
154    }
155
156    switch (key_cmd) {
157    case Opt_new:
158        if (!decrypted_datalen)
159            break;
160        ret = 0;
161        break;
162    case Opt_load:
163        if (!decrypted_datalen)
164            break;
165        *hex_encoded_iv = strsep(&datablob, " \t");
166        if (!*hex_encoded_iv)
167            break;
168        ret = 0;
169        break;
170    case Opt_update:
171        if (decrypted_datalen)
172            break;
173        ret = 0;
174        break;
175    case Opt_err:
176        break;
177    }
178out:
179    return ret;
180}
181
182/*
183 * datablob_format - format as an ascii string, before copying to userspace
184 */
185static char *datablob_format(struct encrypted_key_payload *epayload,
186                 size_t asciiblob_len)
187{
188    char *ascii_buf, *bufp;
189    u8 *iv = epayload->iv;
190    int len;
191    int i;
192
193    ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
194    if (!ascii_buf)
195        goto out;
196
197    ascii_buf[asciiblob_len] = '\0';
198
199    /* copy datablob master_desc and datalen strings */
200    len = sprintf(ascii_buf, "%s %s ", epayload->master_desc,
201              epayload->datalen);
202
203    /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
204    bufp = &ascii_buf[len];
205    for (i = 0; i < (asciiblob_len - len) / 2; i++)
206        bufp = pack_hex_byte(bufp, iv[i]);
207out:
208    return ascii_buf;
209}
210
211/*
212 * request_trusted_key - request the trusted key
213 *
214 * Trusted keys are sealed to PCRs and other metadata. Although userspace
215 * manages both trusted/encrypted key-types, like the encrypted key type
216 * data, trusted key type data is not visible decrypted from userspace.
217 */
218static struct key *request_trusted_key(const char *trusted_desc,
219                       u8 **master_key, size_t *master_keylen)
220{
221    struct trusted_key_payload *tpayload;
222    struct key *tkey;
223
224    tkey = request_key(&key_type_trusted, trusted_desc, NULL);
225    if (IS_ERR(tkey))
226        goto error;
227
228    down_read(&tkey->sem);
229    tpayload = rcu_dereference(tkey->payload.data);
230    *master_key = tpayload->key;
231    *master_keylen = tpayload->key_len;
232error:
233    return tkey;
234}
235
236/*
237 * request_user_key - request the user key
238 *
239 * Use a user provided key to encrypt/decrypt an encrypted-key.
240 */
241static struct key *request_user_key(const char *master_desc, u8 **master_key,
242                    size_t *master_keylen)
243{
244    struct user_key_payload *upayload;
245    struct key *ukey;
246
247    ukey = request_key(&key_type_user, master_desc, NULL);
248    if (IS_ERR(ukey))
249        goto error;
250
251    down_read(&ukey->sem);
252    upayload = rcu_dereference(ukey->payload.data);
253    *master_key = upayload->data;
254    *master_keylen = upayload->datalen;
255error:
256    return ukey;
257}
258
259static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
260{
261    struct sdesc *sdesc;
262    int size;
263
264    size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
265    sdesc = kmalloc(size, GFP_KERNEL);
266    if (!sdesc)
267        return ERR_PTR(-ENOMEM);
268    sdesc->shash.tfm = alg;
269    sdesc->shash.flags = 0x0;
270    return sdesc;
271}
272
273static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
274             const u8 *buf, unsigned int buflen)
275{
276    struct sdesc *sdesc;
277    int ret;
278
279    sdesc = alloc_sdesc(hmacalg);
280    if (IS_ERR(sdesc)) {
281        pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
282        return PTR_ERR(sdesc);
283    }
284
285    ret = crypto_shash_setkey(hmacalg, key, keylen);
286    if (!ret)
287        ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
288    kfree(sdesc);
289    return ret;
290}
291
292static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
293{
294    struct sdesc *sdesc;
295    int ret;
296
297    sdesc = alloc_sdesc(hashalg);
298    if (IS_ERR(sdesc)) {
299        pr_info("encrypted_key: can't alloc %s\n", hash_alg);
300        return PTR_ERR(sdesc);
301    }
302
303    ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
304    kfree(sdesc);
305    return ret;
306}
307
308enum derived_key_type { ENC_KEY, AUTH_KEY };
309
310/* Derive authentication/encryption key from trusted key */
311static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
312               const u8 *master_key, size_t master_keylen)
313{
314    u8 *derived_buf;
315    unsigned int derived_buf_len;
316    int ret;
317
318    derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
319    if (derived_buf_len < HASH_SIZE)
320        derived_buf_len = HASH_SIZE;
321
322    derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
323    if (!derived_buf) {
324        pr_err("encrypted_key: out of memory\n");
325        return -ENOMEM;
326    }
327    if (key_type)
328        strcpy(derived_buf, "AUTH_KEY");
329    else
330        strcpy(derived_buf, "ENC_KEY");
331
332    memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
333           master_keylen);
334    ret = calc_hash(derived_key, derived_buf, derived_buf_len);
335    kfree(derived_buf);
336    return ret;
337}
338
339static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
340                   unsigned int key_len, const u8 *iv,
341                   unsigned int ivsize)
342{
343    int ret;
344
345    desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
346    if (IS_ERR(desc->tfm)) {
347        pr_err("encrypted_key: failed to load %s transform (%ld)\n",
348               blkcipher_alg, PTR_ERR(desc->tfm));
349        return PTR_ERR(desc->tfm);
350    }
351    desc->flags = 0;
352
353    ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
354    if (ret < 0) {
355        pr_err("encrypted_key: failed to setkey (%d)\n", ret);
356        crypto_free_blkcipher(desc->tfm);
357        return ret;
358    }
359    crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
360    return 0;
361}
362
363static struct key *request_master_key(struct encrypted_key_payload *epayload,
364                      u8 **master_key, size_t *master_keylen)
365{
366    struct key *mkey = NULL;
367
368    if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
369             KEY_TRUSTED_PREFIX_LEN)) {
370        mkey = request_trusted_key(epayload->master_desc +
371                       KEY_TRUSTED_PREFIX_LEN,
372                       master_key, master_keylen);
373    } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
374                KEY_USER_PREFIX_LEN)) {
375        mkey = request_user_key(epayload->master_desc +
376                    KEY_USER_PREFIX_LEN,
377                    master_key, master_keylen);
378    } else
379        goto out;
380
381    if (IS_ERR(mkey))
382        pr_info("encrypted_key: key %s not found",
383            epayload->master_desc);
384    if (mkey)
385        dump_master_key(*master_key, *master_keylen);
386out:
387    return mkey;
388}
389
390/* Before returning data to userspace, encrypt decrypted data. */
391static int derived_key_encrypt(struct encrypted_key_payload *epayload,
392                   const u8 *derived_key,
393                   unsigned int derived_keylen)
394{
395    struct scatterlist sg_in[2];
396    struct scatterlist sg_out[1];
397    struct blkcipher_desc desc;
398    unsigned int encrypted_datalen;
399    unsigned int padlen;
400    char pad[16];
401    int ret;
402
403    encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
404    padlen = encrypted_datalen - epayload->decrypted_datalen;
405
406    ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
407                  epayload->iv, ivsize);
408    if (ret < 0)
409        goto out;
410    dump_decrypted_data(epayload);
411
412    memset(pad, 0, sizeof pad);
413    sg_init_table(sg_in, 2);
414    sg_set_buf(&sg_in[0], epayload->decrypted_data,
415           epayload->decrypted_datalen);
416    sg_set_buf(&sg_in[1], pad, padlen);
417
418    sg_init_table(sg_out, 1);
419    sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
420
421    ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
422    crypto_free_blkcipher(desc.tfm);
423    if (ret < 0)
424        pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
425    else
426        dump_encrypted_data(epayload, encrypted_datalen);
427out:
428    return ret;
429}
430
431static int datablob_hmac_append(struct encrypted_key_payload *epayload,
432                const u8 *master_key, size_t master_keylen)
433{
434    u8 derived_key[HASH_SIZE];
435    u8 *digest;
436    int ret;
437
438    ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
439    if (ret < 0)
440        goto out;
441
442    digest = epayload->master_desc + epayload->datablob_len;
443    ret = calc_hmac(digest, derived_key, sizeof derived_key,
444            epayload->master_desc, epayload->datablob_len);
445    if (!ret)
446        dump_hmac(NULL, digest, HASH_SIZE);
447out:
448    return ret;
449}
450
451/* verify HMAC before decrypting encrypted key */
452static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
453                const u8 *master_key, size_t master_keylen)
454{
455    u8 derived_key[HASH_SIZE];
456    u8 digest[HASH_SIZE];
457    int ret;
458
459    ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
460    if (ret < 0)
461        goto out;
462
463    ret = calc_hmac(digest, derived_key, sizeof derived_key,
464            epayload->master_desc, epayload->datablob_len);
465    if (ret < 0)
466        goto out;
467    ret = memcmp(digest, epayload->master_desc + epayload->datablob_len,
468             sizeof digest);
469    if (ret) {
470        ret = -EINVAL;
471        dump_hmac("datablob",
472              epayload->master_desc + epayload->datablob_len,
473              HASH_SIZE);
474        dump_hmac("calc", digest, HASH_SIZE);
475    }
476out:
477    return ret;
478}
479
480static int derived_key_decrypt(struct encrypted_key_payload *epayload,
481                   const u8 *derived_key,
482                   unsigned int derived_keylen)
483{
484    struct scatterlist sg_in[1];
485    struct scatterlist sg_out[2];
486    struct blkcipher_desc desc;
487    unsigned int encrypted_datalen;
488    char pad[16];
489    int ret;
490
491    encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
492    ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
493                  epayload->iv, ivsize);
494    if (ret < 0)
495        goto out;
496    dump_encrypted_data(epayload, encrypted_datalen);
497
498    memset(pad, 0, sizeof pad);
499    sg_init_table(sg_in, 1);
500    sg_init_table(sg_out, 2);
501    sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
502    sg_set_buf(&sg_out[0], epayload->decrypted_data,
503           epayload->decrypted_datalen);
504    sg_set_buf(&sg_out[1], pad, sizeof pad);
505
506    ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
507    crypto_free_blkcipher(desc.tfm);
508    if (ret < 0)
509        goto out;
510    dump_decrypted_data(epayload);
511out:
512    return ret;
513}
514
515/* Allocate memory for decrypted key and datablob. */
516static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
517                             const char *master_desc,
518                             const char *datalen)
519{
520    struct encrypted_key_payload *epayload = NULL;
521    unsigned short datablob_len;
522    unsigned short decrypted_datalen;
523    unsigned int encrypted_datalen;
524    long dlen;
525    int ret;
526
527    ret = strict_strtol(datalen, 10, &dlen);
528    if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
529        return ERR_PTR(-EINVAL);
530
531    decrypted_datalen = dlen;
532    encrypted_datalen = roundup(decrypted_datalen, blksize);
533
534    datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1
535        + ivsize + 1 + encrypted_datalen;
536
537    ret = key_payload_reserve(key, decrypted_datalen + datablob_len
538                  + HASH_SIZE + 1);
539    if (ret < 0)
540        return ERR_PTR(ret);
541
542    epayload = kzalloc(sizeof(*epayload) + decrypted_datalen +
543               datablob_len + HASH_SIZE + 1, GFP_KERNEL);
544    if (!epayload)
545        return ERR_PTR(-ENOMEM);
546
547    epayload->decrypted_datalen = decrypted_datalen;
548    epayload->datablob_len = datablob_len;
549    return epayload;
550}
551
552static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
553                 const char *hex_encoded_iv)
554{
555    struct key *mkey;
556    u8 derived_key[HASH_SIZE];
557    u8 *master_key;
558    u8 *hmac;
559    const char *hex_encoded_data;
560    unsigned int encrypted_datalen;
561    size_t master_keylen;
562    size_t asciilen;
563    int ret;
564
565    encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
566    asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
567    if (strlen(hex_encoded_iv) != asciilen)
568        return -EINVAL;
569
570    hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
571    hex2bin(epayload->iv, hex_encoded_iv, ivsize);
572    hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen);
573
574    hmac = epayload->master_desc + epayload->datablob_len;
575    hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE);
576
577    mkey = request_master_key(epayload, &master_key, &master_keylen);
578    if (IS_ERR(mkey))
579        return PTR_ERR(mkey);
580
581    ret = datablob_hmac_verify(epayload, master_key, master_keylen);
582    if (ret < 0) {
583        pr_err("encrypted_key: bad hmac (%d)\n", ret);
584        goto out;
585    }
586
587    ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
588    if (ret < 0)
589        goto out;
590
591    ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
592    if (ret < 0)
593        pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
594out:
595    up_read(&mkey->sem);
596    key_put(mkey);
597    return ret;
598}
599
600static void __ekey_init(struct encrypted_key_payload *epayload,
601            const char *master_desc, const char *datalen)
602{
603    epayload->master_desc = epayload->decrypted_data
604        + epayload->decrypted_datalen;
605    epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
606    epayload->iv = epayload->datalen + strlen(datalen) + 1;
607    epayload->encrypted_data = epayload->iv + ivsize + 1;
608
609    memcpy(epayload->master_desc, master_desc, strlen(master_desc));
610    memcpy(epayload->datalen, datalen, strlen(datalen));
611}
612
613/*
614 * encrypted_init - initialize an encrypted key
615 *
616 * For a new key, use a random number for both the iv and data
617 * itself. For an old key, decrypt the hex encoded data.
618 */
619static int encrypted_init(struct encrypted_key_payload *epayload,
620              const char *master_desc, const char *datalen,
621              const char *hex_encoded_iv)
622{
623    int ret = 0;
624
625    __ekey_init(epayload, master_desc, datalen);
626    if (!hex_encoded_iv) {
627        get_random_bytes(epayload->iv, ivsize);
628
629        get_random_bytes(epayload->decrypted_data,
630                 epayload->decrypted_datalen);
631    } else
632        ret = encrypted_key_decrypt(epayload, hex_encoded_iv);
633    return ret;
634}
635
636/*
637 * encrypted_instantiate - instantiate an encrypted key
638 *
639 * Decrypt an existing encrypted datablob or create a new encrypted key
640 * based on a kernel random number.
641 *
642 * On success, return 0. Otherwise return errno.
643 */
644static int encrypted_instantiate(struct key *key, const void *data,
645                 size_t datalen)
646{
647    struct encrypted_key_payload *epayload = NULL;
648    char *datablob = NULL;
649    char *master_desc = NULL;
650    char *decrypted_datalen = NULL;
651    char *hex_encoded_iv = NULL;
652    int ret;
653
654    if (datalen <= 0 || datalen > 32767 || !data)
655        return -EINVAL;
656
657    datablob = kmalloc(datalen + 1, GFP_KERNEL);
658    if (!datablob)
659        return -ENOMEM;
660    datablob[datalen] = 0;
661    memcpy(datablob, data, datalen);
662    ret = datablob_parse(datablob, &master_desc, &decrypted_datalen,
663                 &hex_encoded_iv);
664    if (ret < 0)
665        goto out;
666
667    epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen);
668    if (IS_ERR(epayload)) {
669        ret = PTR_ERR(epayload);
670        goto out;
671    }
672    ret = encrypted_init(epayload, master_desc, decrypted_datalen,
673                 hex_encoded_iv);
674    if (ret < 0) {
675        kfree(epayload);
676        goto out;
677    }
678
679    rcu_assign_pointer(key->payload.data, epayload);
680out:
681    kfree(datablob);
682    return ret;
683}
684
685static void encrypted_rcu_free(struct rcu_head *rcu)
686{
687    struct encrypted_key_payload *epayload;
688
689    epayload = container_of(rcu, struct encrypted_key_payload, rcu);
690    memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
691    kfree(epayload);
692}
693
694/*
695 * encrypted_update - update the master key description
696 *
697 * Change the master key description for an existing encrypted key.
698 * The next read will return an encrypted datablob using the new
699 * master key description.
700 *
701 * On success, return 0. Otherwise return errno.
702 */
703static int encrypted_update(struct key *key, const void *data, size_t datalen)
704{
705    struct encrypted_key_payload *epayload = key->payload.data;
706    struct encrypted_key_payload *new_epayload;
707    char *buf;
708    char *new_master_desc = NULL;
709    int ret = 0;
710
711    if (datalen <= 0 || datalen > 32767 || !data)
712        return -EINVAL;
713
714    buf = kmalloc(datalen + 1, GFP_KERNEL);
715    if (!buf)
716        return -ENOMEM;
717
718    buf[datalen] = 0;
719    memcpy(buf, data, datalen);
720    ret = datablob_parse(buf, &new_master_desc, NULL, NULL);
721    if (ret < 0)
722        goto out;
723
724    ret = valid_master_desc(new_master_desc, epayload->master_desc);
725    if (ret < 0)
726        goto out;
727
728    new_epayload = encrypted_key_alloc(key, new_master_desc,
729                       epayload->datalen);
730    if (IS_ERR(new_epayload)) {
731        ret = PTR_ERR(new_epayload);
732        goto out;
733    }
734
735    __ekey_init(new_epayload, new_master_desc, epayload->datalen);
736
737    memcpy(new_epayload->iv, epayload->iv, ivsize);
738    memcpy(new_epayload->decrypted_data, epayload->decrypted_data,
739           epayload->decrypted_datalen);
740
741    rcu_assign_pointer(key->payload.data, new_epayload);
742    call_rcu(&epayload->rcu, encrypted_rcu_free);
743out:
744    kfree(buf);
745    return ret;
746}
747
748/*
749 * encrypted_read - format and copy the encrypted data to userspace
750 *
751 * The resulting datablob format is:
752 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
753 *
754 * On success, return to userspace the encrypted key datablob size.
755 */
756static long encrypted_read(const struct key *key, char __user *buffer,
757               size_t buflen)
758{
759    struct encrypted_key_payload *epayload;
760    struct key *mkey;
761    u8 *master_key;
762    size_t master_keylen;
763    char derived_key[HASH_SIZE];
764    char *ascii_buf;
765    size_t asciiblob_len;
766    int ret;
767
768    epayload = rcu_dereference_key(key);
769
770    /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
771    asciiblob_len = epayload->datablob_len + ivsize + 1
772        + roundup(epayload->decrypted_datalen, blksize)
773        + (HASH_SIZE * 2);
774
775    if (!buffer || buflen < asciiblob_len)
776        return asciiblob_len;
777
778    mkey = request_master_key(epayload, &master_key, &master_keylen);
779    if (IS_ERR(mkey))
780        return PTR_ERR(mkey);
781
782    ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
783    if (ret < 0)
784        goto out;
785
786    ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
787    if (ret < 0)
788        goto out;
789
790    ret = datablob_hmac_append(epayload, master_key, master_keylen);
791    if (ret < 0)
792        goto out;
793
794    ascii_buf = datablob_format(epayload, asciiblob_len);
795    if (!ascii_buf) {
796        ret = -ENOMEM;
797        goto out;
798    }
799
800    up_read(&mkey->sem);
801    key_put(mkey);
802
803    if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
804        ret = -EFAULT;
805    kfree(ascii_buf);
806
807    return asciiblob_len;
808out:
809    up_read(&mkey->sem);
810    key_put(mkey);
811    return ret;
812}
813
814/*
815 * encrypted_destroy - before freeing the key, clear the decrypted data
816 *
817 * Before freeing the key, clear the memory containing the decrypted
818 * key data.
819 */
820static void encrypted_destroy(struct key *key)
821{
822    struct encrypted_key_payload *epayload = key->payload.data;
823
824    if (!epayload)
825        return;
826
827    memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
828    kfree(key->payload.data);
829}
830
831struct key_type key_type_encrypted = {
832    .name = "encrypted",
833    .instantiate = encrypted_instantiate,
834    .update = encrypted_update,
835    .match = user_match,
836    .destroy = encrypted_destroy,
837    .describe = user_describe,
838    .read = encrypted_read,
839};
840EXPORT_SYMBOL_GPL(key_type_encrypted);
841
842static void encrypted_shash_release(void)
843{
844    if (hashalg)
845        crypto_free_shash(hashalg);
846    if (hmacalg)
847        crypto_free_shash(hmacalg);
848}
849
850static int __init encrypted_shash_alloc(void)
851{
852    int ret;
853
854    hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
855    if (IS_ERR(hmacalg)) {
856        pr_info("encrypted_key: could not allocate crypto %s\n",
857            hmac_alg);
858        return PTR_ERR(hmacalg);
859    }
860
861    hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
862    if (IS_ERR(hashalg)) {
863        pr_info("encrypted_key: could not allocate crypto %s\n",
864            hash_alg);
865        ret = PTR_ERR(hashalg);
866        goto hashalg_fail;
867    }
868
869    return 0;
870
871hashalg_fail:
872    crypto_free_shash(hmacalg);
873    return ret;
874}
875
876static int __init init_encrypted(void)
877{
878    int ret;
879
880    ret = encrypted_shash_alloc();
881    if (ret < 0)
882        return ret;
883    ret = register_key_type(&key_type_encrypted);
884    if (ret < 0)
885        goto out;
886    return aes_get_sizes();
887out:
888    encrypted_shash_release();
889    return ret;
890
891}
892
893static void __exit cleanup_encrypted(void)
894{
895    encrypted_shash_release();
896    unregister_key_type(&key_type_encrypted);
897}
898
899late_initcall(init_encrypted);
900module_exit(cleanup_encrypted);
901
902MODULE_LICENSE("GPL");
903

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