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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2010 IBM Corporation
0004  * Copyright (C) 2010 Politecnico di Torino, Italy
0005  *                    TORSEC group -- https://security.polito.it
0006  *
0007  * Authors:
0008  * Mimi Zohar <zohar@us.ibm.com>
0009  * Roberto Sassu <roberto.sassu@polito.it>
0010  *
0011  * See Documentation/security/keys/trusted-encrypted.rst
0012  */
0013 
0014 #include <linux/uaccess.h>
0015 #include <linux/module.h>
0016 #include <linux/init.h>
0017 #include <linux/slab.h>
0018 #include <linux/parser.h>
0019 #include <linux/string.h>
0020 #include <linux/err.h>
0021 #include <keys/user-type.h>
0022 #include <keys/trusted-type.h>
0023 #include <keys/encrypted-type.h>
0024 #include <linux/key-type.h>
0025 #include <linux/random.h>
0026 #include <linux/rcupdate.h>
0027 #include <linux/scatterlist.h>
0028 #include <linux/ctype.h>
0029 #include <crypto/aes.h>
0030 #include <crypto/algapi.h>
0031 #include <crypto/hash.h>
0032 #include <crypto/sha2.h>
0033 #include <crypto/skcipher.h>
0034 
0035 #include "encrypted.h"
0036 #include "ecryptfs_format.h"
0037 
0038 static const char KEY_TRUSTED_PREFIX[] = "trusted:";
0039 static const char KEY_USER_PREFIX[] = "user:";
0040 static const char hash_alg[] = "sha256";
0041 static const char hmac_alg[] = "hmac(sha256)";
0042 static const char blkcipher_alg[] = "cbc(aes)";
0043 static const char key_format_default[] = "default";
0044 static const char key_format_ecryptfs[] = "ecryptfs";
0045 static const char key_format_enc32[] = "enc32";
0046 static unsigned int ivsize;
0047 static int blksize;
0048 
0049 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
0050 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
0051 #define KEY_ECRYPTFS_DESC_LEN 16
0052 #define HASH_SIZE SHA256_DIGEST_SIZE
0053 #define MAX_DATA_SIZE 4096
0054 #define MIN_DATA_SIZE  20
0055 #define KEY_ENC32_PAYLOAD_LEN 32
0056 
0057 static struct crypto_shash *hash_tfm;
0058 
0059 enum {
0060     Opt_new, Opt_load, Opt_update, Opt_err
0061 };
0062 
0063 enum {
0064     Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error
0065 };
0066 
0067 static const match_table_t key_format_tokens = {
0068     {Opt_default, "default"},
0069     {Opt_ecryptfs, "ecryptfs"},
0070     {Opt_enc32, "enc32"},
0071     {Opt_error, NULL}
0072 };
0073 
0074 static const match_table_t key_tokens = {
0075     {Opt_new, "new"},
0076     {Opt_load, "load"},
0077     {Opt_update, "update"},
0078     {Opt_err, NULL}
0079 };
0080 
0081 static bool user_decrypted_data = IS_ENABLED(CONFIG_USER_DECRYPTED_DATA);
0082 module_param(user_decrypted_data, bool, 0);
0083 MODULE_PARM_DESC(user_decrypted_data,
0084     "Allow instantiation of encrypted keys using provided decrypted data");
0085 
0086 static int aes_get_sizes(void)
0087 {
0088     struct crypto_skcipher *tfm;
0089 
0090     tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
0091     if (IS_ERR(tfm)) {
0092         pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
0093                PTR_ERR(tfm));
0094         return PTR_ERR(tfm);
0095     }
0096     ivsize = crypto_skcipher_ivsize(tfm);
0097     blksize = crypto_skcipher_blocksize(tfm);
0098     crypto_free_skcipher(tfm);
0099     return 0;
0100 }
0101 
0102 /*
0103  * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
0104  *
0105  * The description of a encrypted key with format 'ecryptfs' must contain
0106  * exactly 16 hexadecimal characters.
0107  *
0108  */
0109 static int valid_ecryptfs_desc(const char *ecryptfs_desc)
0110 {
0111     int i;
0112 
0113     if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
0114         pr_err("encrypted_key: key description must be %d hexadecimal "
0115                "characters long\n", KEY_ECRYPTFS_DESC_LEN);
0116         return -EINVAL;
0117     }
0118 
0119     for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
0120         if (!isxdigit(ecryptfs_desc[i])) {
0121             pr_err("encrypted_key: key description must contain "
0122                    "only hexadecimal characters\n");
0123             return -EINVAL;
0124         }
0125     }
0126 
0127     return 0;
0128 }
0129 
0130 /*
0131  * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
0132  *
0133  * key-type:= "trusted:" | "user:"
0134  * desc:= master-key description
0135  *
0136  * Verify that 'key-type' is valid and that 'desc' exists. On key update,
0137  * only the master key description is permitted to change, not the key-type.
0138  * The key-type remains constant.
0139  *
0140  * On success returns 0, otherwise -EINVAL.
0141  */
0142 static int valid_master_desc(const char *new_desc, const char *orig_desc)
0143 {
0144     int prefix_len;
0145 
0146     if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
0147         prefix_len = KEY_TRUSTED_PREFIX_LEN;
0148     else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
0149         prefix_len = KEY_USER_PREFIX_LEN;
0150     else
0151         return -EINVAL;
0152 
0153     if (!new_desc[prefix_len])
0154         return -EINVAL;
0155 
0156     if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
0157         return -EINVAL;
0158 
0159     return 0;
0160 }
0161 
0162 /*
0163  * datablob_parse - parse the keyctl data
0164  *
0165  * datablob format:
0166  * new [<format>] <master-key name> <decrypted data length> [<decrypted data>]
0167  * load [<format>] <master-key name> <decrypted data length>
0168  *     <encrypted iv + data>
0169  * update <new-master-key name>
0170  *
0171  * Tokenizes a copy of the keyctl data, returning a pointer to each token,
0172  * which is null terminated.
0173  *
0174  * On success returns 0, otherwise -EINVAL.
0175  */
0176 static int datablob_parse(char *datablob, const char **format,
0177               char **master_desc, char **decrypted_datalen,
0178               char **hex_encoded_iv, char **decrypted_data)
0179 {
0180     substring_t args[MAX_OPT_ARGS];
0181     int ret = -EINVAL;
0182     int key_cmd;
0183     int key_format;
0184     char *p, *keyword;
0185 
0186     keyword = strsep(&datablob, " \t");
0187     if (!keyword) {
0188         pr_info("encrypted_key: insufficient parameters specified\n");
0189         return ret;
0190     }
0191     key_cmd = match_token(keyword, key_tokens, args);
0192 
0193     /* Get optional format: default | ecryptfs */
0194     p = strsep(&datablob, " \t");
0195     if (!p) {
0196         pr_err("encrypted_key: insufficient parameters specified\n");
0197         return ret;
0198     }
0199 
0200     key_format = match_token(p, key_format_tokens, args);
0201     switch (key_format) {
0202     case Opt_ecryptfs:
0203     case Opt_enc32:
0204     case Opt_default:
0205         *format = p;
0206         *master_desc = strsep(&datablob, " \t");
0207         break;
0208     case Opt_error:
0209         *master_desc = p;
0210         break;
0211     }
0212 
0213     if (!*master_desc) {
0214         pr_info("encrypted_key: master key parameter is missing\n");
0215         goto out;
0216     }
0217 
0218     if (valid_master_desc(*master_desc, NULL) < 0) {
0219         pr_info("encrypted_key: master key parameter \'%s\' "
0220             "is invalid\n", *master_desc);
0221         goto out;
0222     }
0223 
0224     if (decrypted_datalen) {
0225         *decrypted_datalen = strsep(&datablob, " \t");
0226         if (!*decrypted_datalen) {
0227             pr_info("encrypted_key: keylen parameter is missing\n");
0228             goto out;
0229         }
0230     }
0231 
0232     switch (key_cmd) {
0233     case Opt_new:
0234         if (!decrypted_datalen) {
0235             pr_info("encrypted_key: keyword \'%s\' not allowed "
0236                 "when called from .update method\n", keyword);
0237             break;
0238         }
0239         *decrypted_data = strsep(&datablob, " \t");
0240         ret = 0;
0241         break;
0242     case Opt_load:
0243         if (!decrypted_datalen) {
0244             pr_info("encrypted_key: keyword \'%s\' not allowed "
0245                 "when called from .update method\n", keyword);
0246             break;
0247         }
0248         *hex_encoded_iv = strsep(&datablob, " \t");
0249         if (!*hex_encoded_iv) {
0250             pr_info("encrypted_key: hex blob is missing\n");
0251             break;
0252         }
0253         ret = 0;
0254         break;
0255     case Opt_update:
0256         if (decrypted_datalen) {
0257             pr_info("encrypted_key: keyword \'%s\' not allowed "
0258                 "when called from .instantiate method\n",
0259                 keyword);
0260             break;
0261         }
0262         ret = 0;
0263         break;
0264     case Opt_err:
0265         pr_info("encrypted_key: keyword \'%s\' not recognized\n",
0266             keyword);
0267         break;
0268     }
0269 out:
0270     return ret;
0271 }
0272 
0273 /*
0274  * datablob_format - format as an ascii string, before copying to userspace
0275  */
0276 static char *datablob_format(struct encrypted_key_payload *epayload,
0277                  size_t asciiblob_len)
0278 {
0279     char *ascii_buf, *bufp;
0280     u8 *iv = epayload->iv;
0281     int len;
0282     int i;
0283 
0284     ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
0285     if (!ascii_buf)
0286         goto out;
0287 
0288     ascii_buf[asciiblob_len] = '\0';
0289 
0290     /* copy datablob master_desc and datalen strings */
0291     len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
0292               epayload->master_desc, epayload->datalen);
0293 
0294     /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
0295     bufp = &ascii_buf[len];
0296     for (i = 0; i < (asciiblob_len - len) / 2; i++)
0297         bufp = hex_byte_pack(bufp, iv[i]);
0298 out:
0299     return ascii_buf;
0300 }
0301 
0302 /*
0303  * request_user_key - request the user key
0304  *
0305  * Use a user provided key to encrypt/decrypt an encrypted-key.
0306  */
0307 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
0308                     size_t *master_keylen)
0309 {
0310     const struct user_key_payload *upayload;
0311     struct key *ukey;
0312 
0313     ukey = request_key(&key_type_user, master_desc, NULL);
0314     if (IS_ERR(ukey))
0315         goto error;
0316 
0317     down_read(&ukey->sem);
0318     upayload = user_key_payload_locked(ukey);
0319     if (!upayload) {
0320         /* key was revoked before we acquired its semaphore */
0321         up_read(&ukey->sem);
0322         key_put(ukey);
0323         ukey = ERR_PTR(-EKEYREVOKED);
0324         goto error;
0325     }
0326     *master_key = upayload->data;
0327     *master_keylen = upayload->datalen;
0328 error:
0329     return ukey;
0330 }
0331 
0332 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
0333              const u8 *buf, unsigned int buflen)
0334 {
0335     struct crypto_shash *tfm;
0336     int err;
0337 
0338     tfm = crypto_alloc_shash(hmac_alg, 0, 0);
0339     if (IS_ERR(tfm)) {
0340         pr_err("encrypted_key: can't alloc %s transform: %ld\n",
0341                hmac_alg, PTR_ERR(tfm));
0342         return PTR_ERR(tfm);
0343     }
0344 
0345     err = crypto_shash_setkey(tfm, key, keylen);
0346     if (!err)
0347         err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
0348     crypto_free_shash(tfm);
0349     return err;
0350 }
0351 
0352 enum derived_key_type { ENC_KEY, AUTH_KEY };
0353 
0354 /* Derive authentication/encryption key from trusted key */
0355 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
0356                const u8 *master_key, size_t master_keylen)
0357 {
0358     u8 *derived_buf;
0359     unsigned int derived_buf_len;
0360     int ret;
0361 
0362     derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
0363     if (derived_buf_len < HASH_SIZE)
0364         derived_buf_len = HASH_SIZE;
0365 
0366     derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
0367     if (!derived_buf)
0368         return -ENOMEM;
0369 
0370     if (key_type)
0371         strcpy(derived_buf, "AUTH_KEY");
0372     else
0373         strcpy(derived_buf, "ENC_KEY");
0374 
0375     memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
0376            master_keylen);
0377     ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
0378                       derived_key);
0379     kfree_sensitive(derived_buf);
0380     return ret;
0381 }
0382 
0383 static struct skcipher_request *init_skcipher_req(const u8 *key,
0384                           unsigned int key_len)
0385 {
0386     struct skcipher_request *req;
0387     struct crypto_skcipher *tfm;
0388     int ret;
0389 
0390     tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
0391     if (IS_ERR(tfm)) {
0392         pr_err("encrypted_key: failed to load %s transform (%ld)\n",
0393                blkcipher_alg, PTR_ERR(tfm));
0394         return ERR_CAST(tfm);
0395     }
0396 
0397     ret = crypto_skcipher_setkey(tfm, key, key_len);
0398     if (ret < 0) {
0399         pr_err("encrypted_key: failed to setkey (%d)\n", ret);
0400         crypto_free_skcipher(tfm);
0401         return ERR_PTR(ret);
0402     }
0403 
0404     req = skcipher_request_alloc(tfm, GFP_KERNEL);
0405     if (!req) {
0406         pr_err("encrypted_key: failed to allocate request for %s\n",
0407                blkcipher_alg);
0408         crypto_free_skcipher(tfm);
0409         return ERR_PTR(-ENOMEM);
0410     }
0411 
0412     skcipher_request_set_callback(req, 0, NULL, NULL);
0413     return req;
0414 }
0415 
0416 static struct key *request_master_key(struct encrypted_key_payload *epayload,
0417                       const u8 **master_key, size_t *master_keylen)
0418 {
0419     struct key *mkey = ERR_PTR(-EINVAL);
0420 
0421     if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
0422              KEY_TRUSTED_PREFIX_LEN)) {
0423         mkey = request_trusted_key(epayload->master_desc +
0424                        KEY_TRUSTED_PREFIX_LEN,
0425                        master_key, master_keylen);
0426     } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
0427                 KEY_USER_PREFIX_LEN)) {
0428         mkey = request_user_key(epayload->master_desc +
0429                     KEY_USER_PREFIX_LEN,
0430                     master_key, master_keylen);
0431     } else
0432         goto out;
0433 
0434     if (IS_ERR(mkey)) {
0435         int ret = PTR_ERR(mkey);
0436 
0437         if (ret == -ENOTSUPP)
0438             pr_info("encrypted_key: key %s not supported",
0439                 epayload->master_desc);
0440         else
0441             pr_info("encrypted_key: key %s not found",
0442                 epayload->master_desc);
0443         goto out;
0444     }
0445 
0446     dump_master_key(*master_key, *master_keylen);
0447 out:
0448     return mkey;
0449 }
0450 
0451 /* Before returning data to userspace, encrypt decrypted data. */
0452 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
0453                    const u8 *derived_key,
0454                    unsigned int derived_keylen)
0455 {
0456     struct scatterlist sg_in[2];
0457     struct scatterlist sg_out[1];
0458     struct crypto_skcipher *tfm;
0459     struct skcipher_request *req;
0460     unsigned int encrypted_datalen;
0461     u8 iv[AES_BLOCK_SIZE];
0462     int ret;
0463 
0464     encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
0465 
0466     req = init_skcipher_req(derived_key, derived_keylen);
0467     ret = PTR_ERR(req);
0468     if (IS_ERR(req))
0469         goto out;
0470     dump_decrypted_data(epayload);
0471 
0472     sg_init_table(sg_in, 2);
0473     sg_set_buf(&sg_in[0], epayload->decrypted_data,
0474            epayload->decrypted_datalen);
0475     sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
0476 
0477     sg_init_table(sg_out, 1);
0478     sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
0479 
0480     memcpy(iv, epayload->iv, sizeof(iv));
0481     skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
0482     ret = crypto_skcipher_encrypt(req);
0483     tfm = crypto_skcipher_reqtfm(req);
0484     skcipher_request_free(req);
0485     crypto_free_skcipher(tfm);
0486     if (ret < 0)
0487         pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
0488     else
0489         dump_encrypted_data(epayload, encrypted_datalen);
0490 out:
0491     return ret;
0492 }
0493 
0494 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
0495                 const u8 *master_key, size_t master_keylen)
0496 {
0497     u8 derived_key[HASH_SIZE];
0498     u8 *digest;
0499     int ret;
0500 
0501     ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
0502     if (ret < 0)
0503         goto out;
0504 
0505     digest = epayload->format + epayload->datablob_len;
0506     ret = calc_hmac(digest, derived_key, sizeof derived_key,
0507             epayload->format, epayload->datablob_len);
0508     if (!ret)
0509         dump_hmac(NULL, digest, HASH_SIZE);
0510 out:
0511     memzero_explicit(derived_key, sizeof(derived_key));
0512     return ret;
0513 }
0514 
0515 /* verify HMAC before decrypting encrypted key */
0516 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
0517                 const u8 *format, const u8 *master_key,
0518                 size_t master_keylen)
0519 {
0520     u8 derived_key[HASH_SIZE];
0521     u8 digest[HASH_SIZE];
0522     int ret;
0523     char *p;
0524     unsigned short len;
0525 
0526     ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
0527     if (ret < 0)
0528         goto out;
0529 
0530     len = epayload->datablob_len;
0531     if (!format) {
0532         p = epayload->master_desc;
0533         len -= strlen(epayload->format) + 1;
0534     } else
0535         p = epayload->format;
0536 
0537     ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
0538     if (ret < 0)
0539         goto out;
0540     ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
0541                 sizeof(digest));
0542     if (ret) {
0543         ret = -EINVAL;
0544         dump_hmac("datablob",
0545               epayload->format + epayload->datablob_len,
0546               HASH_SIZE);
0547         dump_hmac("calc", digest, HASH_SIZE);
0548     }
0549 out:
0550     memzero_explicit(derived_key, sizeof(derived_key));
0551     return ret;
0552 }
0553 
0554 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
0555                    const u8 *derived_key,
0556                    unsigned int derived_keylen)
0557 {
0558     struct scatterlist sg_in[1];
0559     struct scatterlist sg_out[2];
0560     struct crypto_skcipher *tfm;
0561     struct skcipher_request *req;
0562     unsigned int encrypted_datalen;
0563     u8 iv[AES_BLOCK_SIZE];
0564     u8 *pad;
0565     int ret;
0566 
0567     /* Throwaway buffer to hold the unused zero padding at the end */
0568     pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
0569     if (!pad)
0570         return -ENOMEM;
0571 
0572     encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
0573     req = init_skcipher_req(derived_key, derived_keylen);
0574     ret = PTR_ERR(req);
0575     if (IS_ERR(req))
0576         goto out;
0577     dump_encrypted_data(epayload, encrypted_datalen);
0578 
0579     sg_init_table(sg_in, 1);
0580     sg_init_table(sg_out, 2);
0581     sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
0582     sg_set_buf(&sg_out[0], epayload->decrypted_data,
0583            epayload->decrypted_datalen);
0584     sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
0585 
0586     memcpy(iv, epayload->iv, sizeof(iv));
0587     skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
0588     ret = crypto_skcipher_decrypt(req);
0589     tfm = crypto_skcipher_reqtfm(req);
0590     skcipher_request_free(req);
0591     crypto_free_skcipher(tfm);
0592     if (ret < 0)
0593         goto out;
0594     dump_decrypted_data(epayload);
0595 out:
0596     kfree(pad);
0597     return ret;
0598 }
0599 
0600 /* Allocate memory for decrypted key and datablob. */
0601 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
0602                              const char *format,
0603                              const char *master_desc,
0604                              const char *datalen,
0605                              const char *decrypted_data)
0606 {
0607     struct encrypted_key_payload *epayload = NULL;
0608     unsigned short datablob_len;
0609     unsigned short decrypted_datalen;
0610     unsigned short payload_datalen;
0611     unsigned int encrypted_datalen;
0612     unsigned int format_len;
0613     long dlen;
0614     int i;
0615     int ret;
0616 
0617     ret = kstrtol(datalen, 10, &dlen);
0618     if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
0619         return ERR_PTR(-EINVAL);
0620 
0621     format_len = (!format) ? strlen(key_format_default) : strlen(format);
0622     decrypted_datalen = dlen;
0623     payload_datalen = decrypted_datalen;
0624 
0625     if (decrypted_data) {
0626         if (!user_decrypted_data) {
0627             pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n");
0628             return ERR_PTR(-EINVAL);
0629         }
0630         if (strlen(decrypted_data) != decrypted_datalen) {
0631             pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n");
0632             return ERR_PTR(-EINVAL);
0633         }
0634         for (i = 0; i < strlen(decrypted_data); i++) {
0635             if (!isxdigit(decrypted_data[i])) {
0636                 pr_err("encrypted key: decrypted data provided must contain only hexadecimal characters\n");
0637                 return ERR_PTR(-EINVAL);
0638             }
0639         }
0640     }
0641 
0642     if (format) {
0643         if (!strcmp(format, key_format_ecryptfs)) {
0644             if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
0645                 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n",
0646                     ECRYPTFS_MAX_KEY_BYTES);
0647                 return ERR_PTR(-EINVAL);
0648             }
0649             decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
0650             payload_datalen = sizeof(struct ecryptfs_auth_tok);
0651         } else if (!strcmp(format, key_format_enc32)) {
0652             if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) {
0653                 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n",
0654                         decrypted_datalen);
0655                 return ERR_PTR(-EINVAL);
0656             }
0657         }
0658     }
0659 
0660     encrypted_datalen = roundup(decrypted_datalen, blksize);
0661 
0662     datablob_len = format_len + 1 + strlen(master_desc) + 1
0663         + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
0664 
0665     ret = key_payload_reserve(key, payload_datalen + datablob_len
0666                   + HASH_SIZE + 1);
0667     if (ret < 0)
0668         return ERR_PTR(ret);
0669 
0670     epayload = kzalloc(sizeof(*epayload) + payload_datalen +
0671                datablob_len + HASH_SIZE + 1, GFP_KERNEL);
0672     if (!epayload)
0673         return ERR_PTR(-ENOMEM);
0674 
0675     epayload->payload_datalen = payload_datalen;
0676     epayload->decrypted_datalen = decrypted_datalen;
0677     epayload->datablob_len = datablob_len;
0678     return epayload;
0679 }
0680 
0681 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
0682                  const char *format, const char *hex_encoded_iv)
0683 {
0684     struct key *mkey;
0685     u8 derived_key[HASH_SIZE];
0686     const u8 *master_key;
0687     u8 *hmac;
0688     const char *hex_encoded_data;
0689     unsigned int encrypted_datalen;
0690     size_t master_keylen;
0691     size_t asciilen;
0692     int ret;
0693 
0694     encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
0695     asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
0696     if (strlen(hex_encoded_iv) != asciilen)
0697         return -EINVAL;
0698 
0699     hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
0700     ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
0701     if (ret < 0)
0702         return -EINVAL;
0703     ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
0704               encrypted_datalen);
0705     if (ret < 0)
0706         return -EINVAL;
0707 
0708     hmac = epayload->format + epayload->datablob_len;
0709     ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
0710               HASH_SIZE);
0711     if (ret < 0)
0712         return -EINVAL;
0713 
0714     mkey = request_master_key(epayload, &master_key, &master_keylen);
0715     if (IS_ERR(mkey))
0716         return PTR_ERR(mkey);
0717 
0718     ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
0719     if (ret < 0) {
0720         pr_err("encrypted_key: bad hmac (%d)\n", ret);
0721         goto out;
0722     }
0723 
0724     ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
0725     if (ret < 0)
0726         goto out;
0727 
0728     ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
0729     if (ret < 0)
0730         pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
0731 out:
0732     up_read(&mkey->sem);
0733     key_put(mkey);
0734     memzero_explicit(derived_key, sizeof(derived_key));
0735     return ret;
0736 }
0737 
0738 static void __ekey_init(struct encrypted_key_payload *epayload,
0739             const char *format, const char *master_desc,
0740             const char *datalen)
0741 {
0742     unsigned int format_len;
0743 
0744     format_len = (!format) ? strlen(key_format_default) : strlen(format);
0745     epayload->format = epayload->payload_data + epayload->payload_datalen;
0746     epayload->master_desc = epayload->format + format_len + 1;
0747     epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
0748     epayload->iv = epayload->datalen + strlen(datalen) + 1;
0749     epayload->encrypted_data = epayload->iv + ivsize + 1;
0750     epayload->decrypted_data = epayload->payload_data;
0751 
0752     if (!format)
0753         memcpy(epayload->format, key_format_default, format_len);
0754     else {
0755         if (!strcmp(format, key_format_ecryptfs))
0756             epayload->decrypted_data =
0757                 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
0758 
0759         memcpy(epayload->format, format, format_len);
0760     }
0761 
0762     memcpy(epayload->master_desc, master_desc, strlen(master_desc));
0763     memcpy(epayload->datalen, datalen, strlen(datalen));
0764 }
0765 
0766 /*
0767  * encrypted_init - initialize an encrypted key
0768  *
0769  * For a new key, use either a random number or user-provided decrypted data in
0770  * case it is provided. A random number is used for the iv in both cases. For
0771  * an old key, decrypt the hex encoded data.
0772  */
0773 static int encrypted_init(struct encrypted_key_payload *epayload,
0774               const char *key_desc, const char *format,
0775               const char *master_desc, const char *datalen,
0776               const char *hex_encoded_iv, const char *decrypted_data)
0777 {
0778     int ret = 0;
0779 
0780     if (format && !strcmp(format, key_format_ecryptfs)) {
0781         ret = valid_ecryptfs_desc(key_desc);
0782         if (ret < 0)
0783             return ret;
0784 
0785         ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
0786                        key_desc);
0787     }
0788 
0789     __ekey_init(epayload, format, master_desc, datalen);
0790     if (hex_encoded_iv) {
0791         ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
0792     } else if (decrypted_data) {
0793         get_random_bytes(epayload->iv, ivsize);
0794         memcpy(epayload->decrypted_data, decrypted_data,
0795                    epayload->decrypted_datalen);
0796     } else {
0797         get_random_bytes(epayload->iv, ivsize);
0798         get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen);
0799     }
0800     return ret;
0801 }
0802 
0803 /*
0804  * encrypted_instantiate - instantiate an encrypted key
0805  *
0806  * Instantiates the key:
0807  * - by decrypting an existing encrypted datablob, or
0808  * - by creating a new encrypted key based on a kernel random number, or
0809  * - using provided decrypted data.
0810  *
0811  * On success, return 0. Otherwise return errno.
0812  */
0813 static int encrypted_instantiate(struct key *key,
0814                  struct key_preparsed_payload *prep)
0815 {
0816     struct encrypted_key_payload *epayload = NULL;
0817     char *datablob = NULL;
0818     const char *format = NULL;
0819     char *master_desc = NULL;
0820     char *decrypted_datalen = NULL;
0821     char *hex_encoded_iv = NULL;
0822     char *decrypted_data = NULL;
0823     size_t datalen = prep->datalen;
0824     int ret;
0825 
0826     if (datalen <= 0 || datalen > 32767 || !prep->data)
0827         return -EINVAL;
0828 
0829     datablob = kmalloc(datalen + 1, GFP_KERNEL);
0830     if (!datablob)
0831         return -ENOMEM;
0832     datablob[datalen] = 0;
0833     memcpy(datablob, prep->data, datalen);
0834     ret = datablob_parse(datablob, &format, &master_desc,
0835                  &decrypted_datalen, &hex_encoded_iv, &decrypted_data);
0836     if (ret < 0)
0837         goto out;
0838 
0839     epayload = encrypted_key_alloc(key, format, master_desc,
0840                        decrypted_datalen, decrypted_data);
0841     if (IS_ERR(epayload)) {
0842         ret = PTR_ERR(epayload);
0843         goto out;
0844     }
0845     ret = encrypted_init(epayload, key->description, format, master_desc,
0846                  decrypted_datalen, hex_encoded_iv, decrypted_data);
0847     if (ret < 0) {
0848         kfree_sensitive(epayload);
0849         goto out;
0850     }
0851 
0852     rcu_assign_keypointer(key, epayload);
0853 out:
0854     kfree_sensitive(datablob);
0855     return ret;
0856 }
0857 
0858 static void encrypted_rcu_free(struct rcu_head *rcu)
0859 {
0860     struct encrypted_key_payload *epayload;
0861 
0862     epayload = container_of(rcu, struct encrypted_key_payload, rcu);
0863     kfree_sensitive(epayload);
0864 }
0865 
0866 /*
0867  * encrypted_update - update the master key description
0868  *
0869  * Change the master key description for an existing encrypted key.
0870  * The next read will return an encrypted datablob using the new
0871  * master key description.
0872  *
0873  * On success, return 0. Otherwise return errno.
0874  */
0875 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
0876 {
0877     struct encrypted_key_payload *epayload = key->payload.data[0];
0878     struct encrypted_key_payload *new_epayload;
0879     char *buf;
0880     char *new_master_desc = NULL;
0881     const char *format = NULL;
0882     size_t datalen = prep->datalen;
0883     int ret = 0;
0884 
0885     if (key_is_negative(key))
0886         return -ENOKEY;
0887     if (datalen <= 0 || datalen > 32767 || !prep->data)
0888         return -EINVAL;
0889 
0890     buf = kmalloc(datalen + 1, GFP_KERNEL);
0891     if (!buf)
0892         return -ENOMEM;
0893 
0894     buf[datalen] = 0;
0895     memcpy(buf, prep->data, datalen);
0896     ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL, NULL);
0897     if (ret < 0)
0898         goto out;
0899 
0900     ret = valid_master_desc(new_master_desc, epayload->master_desc);
0901     if (ret < 0)
0902         goto out;
0903 
0904     new_epayload = encrypted_key_alloc(key, epayload->format,
0905                        new_master_desc, epayload->datalen, NULL);
0906     if (IS_ERR(new_epayload)) {
0907         ret = PTR_ERR(new_epayload);
0908         goto out;
0909     }
0910 
0911     __ekey_init(new_epayload, epayload->format, new_master_desc,
0912             epayload->datalen);
0913 
0914     memcpy(new_epayload->iv, epayload->iv, ivsize);
0915     memcpy(new_epayload->payload_data, epayload->payload_data,
0916            epayload->payload_datalen);
0917 
0918     rcu_assign_keypointer(key, new_epayload);
0919     call_rcu(&epayload->rcu, encrypted_rcu_free);
0920 out:
0921     kfree_sensitive(buf);
0922     return ret;
0923 }
0924 
0925 /*
0926  * encrypted_read - format and copy out the encrypted data
0927  *
0928  * The resulting datablob format is:
0929  * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
0930  *
0931  * On success, return to userspace the encrypted key datablob size.
0932  */
0933 static long encrypted_read(const struct key *key, char *buffer,
0934                size_t buflen)
0935 {
0936     struct encrypted_key_payload *epayload;
0937     struct key *mkey;
0938     const u8 *master_key;
0939     size_t master_keylen;
0940     char derived_key[HASH_SIZE];
0941     char *ascii_buf;
0942     size_t asciiblob_len;
0943     int ret;
0944 
0945     epayload = dereference_key_locked(key);
0946 
0947     /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
0948     asciiblob_len = epayload->datablob_len + ivsize + 1
0949         + roundup(epayload->decrypted_datalen, blksize)
0950         + (HASH_SIZE * 2);
0951 
0952     if (!buffer || buflen < asciiblob_len)
0953         return asciiblob_len;
0954 
0955     mkey = request_master_key(epayload, &master_key, &master_keylen);
0956     if (IS_ERR(mkey))
0957         return PTR_ERR(mkey);
0958 
0959     ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
0960     if (ret < 0)
0961         goto out;
0962 
0963     ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
0964     if (ret < 0)
0965         goto out;
0966 
0967     ret = datablob_hmac_append(epayload, master_key, master_keylen);
0968     if (ret < 0)
0969         goto out;
0970 
0971     ascii_buf = datablob_format(epayload, asciiblob_len);
0972     if (!ascii_buf) {
0973         ret = -ENOMEM;
0974         goto out;
0975     }
0976 
0977     up_read(&mkey->sem);
0978     key_put(mkey);
0979     memzero_explicit(derived_key, sizeof(derived_key));
0980 
0981     memcpy(buffer, ascii_buf, asciiblob_len);
0982     kfree_sensitive(ascii_buf);
0983 
0984     return asciiblob_len;
0985 out:
0986     up_read(&mkey->sem);
0987     key_put(mkey);
0988     memzero_explicit(derived_key, sizeof(derived_key));
0989     return ret;
0990 }
0991 
0992 /*
0993  * encrypted_destroy - clear and free the key's payload
0994  */
0995 static void encrypted_destroy(struct key *key)
0996 {
0997     kfree_sensitive(key->payload.data[0]);
0998 }
0999 
1000 struct key_type key_type_encrypted = {
1001     .name = "encrypted",
1002     .instantiate = encrypted_instantiate,
1003     .update = encrypted_update,
1004     .destroy = encrypted_destroy,
1005     .describe = user_describe,
1006     .read = encrypted_read,
1007 };
1008 EXPORT_SYMBOL_GPL(key_type_encrypted);
1009 
1010 static int __init init_encrypted(void)
1011 {
1012     int ret;
1013 
1014     hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
1015     if (IS_ERR(hash_tfm)) {
1016         pr_err("encrypted_key: can't allocate %s transform: %ld\n",
1017                hash_alg, PTR_ERR(hash_tfm));
1018         return PTR_ERR(hash_tfm);
1019     }
1020 
1021     ret = aes_get_sizes();
1022     if (ret < 0)
1023         goto out;
1024     ret = register_key_type(&key_type_encrypted);
1025     if (ret < 0)
1026         goto out;
1027     return 0;
1028 out:
1029     crypto_free_shash(hash_tfm);
1030     return ret;
1031 
1032 }
1033 
1034 static void __exit cleanup_encrypted(void)
1035 {
1036     crypto_free_shash(hash_tfm);
1037     unregister_key_type(&key_type_encrypted);
1038 }
1039 
1040 late_initcall(init_encrypted);
1041 module_exit(cleanup_encrypted);
1042 
1043 MODULE_LICENSE("GPL");
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