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1010 lines
26 KiB
1010 lines
26 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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* Copyright (C) 2010 IBM Corporation |
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* Copyright (C) 2010 Politecnico di Torino, Italy |
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* TORSEC group -- https://security.polito.it |
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* |
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* Authors: |
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* Mimi Zohar <[email protected]> |
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* Roberto Sassu <[email protected]> |
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* |
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* See Documentation/security/keys/trusted-encrypted.rst |
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*/ |
|
|
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#include <linux/uaccess.h> |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/parser.h> |
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#include <linux/string.h> |
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#include <linux/err.h> |
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#include <keys/user-type.h> |
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#include <keys/trusted-type.h> |
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#include <keys/encrypted-type.h> |
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#include <linux/key-type.h> |
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#include <linux/random.h> |
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#include <linux/rcupdate.h> |
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#include <linux/scatterlist.h> |
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#include <linux/ctype.h> |
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#include <crypto/aes.h> |
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#include <crypto/algapi.h> |
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#include <crypto/hash.h> |
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#include <crypto/sha2.h> |
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#include <crypto/skcipher.h> |
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|
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#include "encrypted.h" |
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#include "ecryptfs_format.h" |
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|
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static const char KEY_TRUSTED_PREFIX[] = "trusted:"; |
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static const char KEY_USER_PREFIX[] = "user:"; |
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static const char hash_alg[] = "sha256"; |
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static const char hmac_alg[] = "hmac(sha256)"; |
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static const char blkcipher_alg[] = "cbc(aes)"; |
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static const char key_format_default[] = "default"; |
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static const char key_format_ecryptfs[] = "ecryptfs"; |
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static const char key_format_enc32[] = "enc32"; |
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static unsigned int ivsize; |
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static int blksize; |
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|
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#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) |
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#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) |
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#define KEY_ECRYPTFS_DESC_LEN 16 |
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#define HASH_SIZE SHA256_DIGEST_SIZE |
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#define MAX_DATA_SIZE 4096 |
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#define MIN_DATA_SIZE 20 |
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#define KEY_ENC32_PAYLOAD_LEN 32 |
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|
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static struct crypto_shash *hash_tfm; |
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|
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enum { |
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Opt_new, Opt_load, Opt_update, Opt_err |
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}; |
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|
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enum { |
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Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error |
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}; |
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|
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static const match_table_t key_format_tokens = { |
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{Opt_default, "default"}, |
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{Opt_ecryptfs, "ecryptfs"}, |
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{Opt_enc32, "enc32"}, |
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{Opt_error, NULL} |
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}; |
|
|
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static const match_table_t key_tokens = { |
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{Opt_new, "new"}, |
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{Opt_load, "load"}, |
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{Opt_update, "update"}, |
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{Opt_err, NULL} |
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}; |
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|
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static int aes_get_sizes(void) |
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{ |
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struct crypto_skcipher *tfm; |
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|
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tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); |
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if (IS_ERR(tfm)) { |
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pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", |
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PTR_ERR(tfm)); |
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return PTR_ERR(tfm); |
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} |
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ivsize = crypto_skcipher_ivsize(tfm); |
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blksize = crypto_skcipher_blocksize(tfm); |
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crypto_free_skcipher(tfm); |
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return 0; |
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} |
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|
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/* |
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* valid_ecryptfs_desc - verify the description of a new/loaded encrypted key |
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* |
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* The description of a encrypted key with format 'ecryptfs' must contain |
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* exactly 16 hexadecimal characters. |
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* |
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*/ |
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static int valid_ecryptfs_desc(const char *ecryptfs_desc) |
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{ |
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int i; |
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|
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if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { |
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pr_err("encrypted_key: key description must be %d hexadecimal " |
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"characters long\n", KEY_ECRYPTFS_DESC_LEN); |
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return -EINVAL; |
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} |
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|
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for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { |
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if (!isxdigit(ecryptfs_desc[i])) { |
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pr_err("encrypted_key: key description must contain " |
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"only hexadecimal characters\n"); |
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return -EINVAL; |
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} |
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} |
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|
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return 0; |
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} |
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|
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/* |
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* valid_master_desc - verify the 'key-type:desc' of a new/updated master-key |
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* |
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* key-type:= "trusted:" | "user:" |
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* desc:= master-key description |
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* |
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* Verify that 'key-type' is valid and that 'desc' exists. On key update, |
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* only the master key description is permitted to change, not the key-type. |
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* The key-type remains constant. |
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* |
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* On success returns 0, otherwise -EINVAL. |
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*/ |
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static int valid_master_desc(const char *new_desc, const char *orig_desc) |
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{ |
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int prefix_len; |
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|
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if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) |
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prefix_len = KEY_TRUSTED_PREFIX_LEN; |
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else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) |
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prefix_len = KEY_USER_PREFIX_LEN; |
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else |
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return -EINVAL; |
|
|
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if (!new_desc[prefix_len]) |
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return -EINVAL; |
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|
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if (orig_desc && strncmp(new_desc, orig_desc, prefix_len)) |
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return -EINVAL; |
|
|
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return 0; |
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} |
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|
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/* |
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* datablob_parse - parse the keyctl data |
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* |
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* datablob format: |
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* new [<format>] <master-key name> <decrypted data length> |
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* load [<format>] <master-key name> <decrypted data length> |
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* <encrypted iv + data> |
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* update <new-master-key name> |
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* |
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* Tokenizes a copy of the keyctl data, returning a pointer to each token, |
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* which is null terminated. |
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* |
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* On success returns 0, otherwise -EINVAL. |
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*/ |
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static int datablob_parse(char *datablob, const char **format, |
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char **master_desc, char **decrypted_datalen, |
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char **hex_encoded_iv) |
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{ |
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substring_t args[MAX_OPT_ARGS]; |
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int ret = -EINVAL; |
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int key_cmd; |
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int key_format; |
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char *p, *keyword; |
|
|
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keyword = strsep(&datablob, " \t"); |
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if (!keyword) { |
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pr_info("encrypted_key: insufficient parameters specified\n"); |
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return ret; |
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} |
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key_cmd = match_token(keyword, key_tokens, args); |
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|
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/* Get optional format: default | ecryptfs */ |
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p = strsep(&datablob, " \t"); |
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if (!p) { |
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pr_err("encrypted_key: insufficient parameters specified\n"); |
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return ret; |
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} |
|
|
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key_format = match_token(p, key_format_tokens, args); |
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switch (key_format) { |
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case Opt_ecryptfs: |
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case Opt_enc32: |
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case Opt_default: |
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*format = p; |
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*master_desc = strsep(&datablob, " \t"); |
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break; |
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case Opt_error: |
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*master_desc = p; |
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break; |
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} |
|
|
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if (!*master_desc) { |
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pr_info("encrypted_key: master key parameter is missing\n"); |
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goto out; |
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} |
|
|
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if (valid_master_desc(*master_desc, NULL) < 0) { |
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pr_info("encrypted_key: master key parameter \'%s\' " |
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"is invalid\n", *master_desc); |
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goto out; |
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} |
|
|
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if (decrypted_datalen) { |
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*decrypted_datalen = strsep(&datablob, " \t"); |
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if (!*decrypted_datalen) { |
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pr_info("encrypted_key: keylen parameter is missing\n"); |
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goto out; |
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} |
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} |
|
|
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switch (key_cmd) { |
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case Opt_new: |
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if (!decrypted_datalen) { |
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pr_info("encrypted_key: keyword \'%s\' not allowed " |
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"when called from .update method\n", keyword); |
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break; |
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} |
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ret = 0; |
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break; |
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case Opt_load: |
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if (!decrypted_datalen) { |
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pr_info("encrypted_key: keyword \'%s\' not allowed " |
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"when called from .update method\n", keyword); |
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break; |
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} |
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*hex_encoded_iv = strsep(&datablob, " \t"); |
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if (!*hex_encoded_iv) { |
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pr_info("encrypted_key: hex blob is missing\n"); |
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break; |
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} |
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ret = 0; |
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break; |
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case Opt_update: |
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if (decrypted_datalen) { |
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pr_info("encrypted_key: keyword \'%s\' not allowed " |
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"when called from .instantiate method\n", |
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keyword); |
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break; |
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} |
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ret = 0; |
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break; |
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case Opt_err: |
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pr_info("encrypted_key: keyword \'%s\' not recognized\n", |
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keyword); |
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break; |
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} |
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out: |
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return ret; |
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} |
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|
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/* |
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* datablob_format - format as an ascii string, before copying to userspace |
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*/ |
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static char *datablob_format(struct encrypted_key_payload *epayload, |
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size_t asciiblob_len) |
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{ |
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char *ascii_buf, *bufp; |
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u8 *iv = epayload->iv; |
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int len; |
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int i; |
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|
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ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); |
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if (!ascii_buf) |
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goto out; |
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|
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ascii_buf[asciiblob_len] = '\0'; |
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|
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/* copy datablob master_desc and datalen strings */ |
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len = sprintf(ascii_buf, "%s %s %s ", epayload->format, |
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epayload->master_desc, epayload->datalen); |
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|
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/* convert the hex encoded iv, encrypted-data and HMAC to ascii */ |
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bufp = &ascii_buf[len]; |
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for (i = 0; i < (asciiblob_len - len) / 2; i++) |
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bufp = hex_byte_pack(bufp, iv[i]); |
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out: |
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return ascii_buf; |
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} |
|
|
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/* |
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* request_user_key - request the user key |
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* |
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* Use a user provided key to encrypt/decrypt an encrypted-key. |
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*/ |
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static struct key *request_user_key(const char *master_desc, const u8 **master_key, |
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size_t *master_keylen) |
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{ |
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const struct user_key_payload *upayload; |
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struct key *ukey; |
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|
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ukey = request_key(&key_type_user, master_desc, NULL); |
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if (IS_ERR(ukey)) |
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goto error; |
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|
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down_read(&ukey->sem); |
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upayload = user_key_payload_locked(ukey); |
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if (!upayload) { |
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/* key was revoked before we acquired its semaphore */ |
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up_read(&ukey->sem); |
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key_put(ukey); |
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ukey = ERR_PTR(-EKEYREVOKED); |
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goto error; |
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} |
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*master_key = upayload->data; |
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*master_keylen = upayload->datalen; |
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error: |
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return ukey; |
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} |
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|
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static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, |
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const u8 *buf, unsigned int buflen) |
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{ |
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struct crypto_shash *tfm; |
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int err; |
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|
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tfm = crypto_alloc_shash(hmac_alg, 0, 0); |
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if (IS_ERR(tfm)) { |
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pr_err("encrypted_key: can't alloc %s transform: %ld\n", |
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hmac_alg, PTR_ERR(tfm)); |
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return PTR_ERR(tfm); |
|
} |
|
|
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err = crypto_shash_setkey(tfm, key, keylen); |
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if (!err) |
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err = crypto_shash_tfm_digest(tfm, buf, buflen, digest); |
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crypto_free_shash(tfm); |
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return err; |
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} |
|
|
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enum derived_key_type { ENC_KEY, AUTH_KEY }; |
|
|
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/* Derive authentication/encryption key from trusted key */ |
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static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, |
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const u8 *master_key, size_t master_keylen) |
|
{ |
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u8 *derived_buf; |
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unsigned int derived_buf_len; |
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int ret; |
|
|
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derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; |
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if (derived_buf_len < HASH_SIZE) |
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derived_buf_len = HASH_SIZE; |
|
|
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derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); |
|
if (!derived_buf) |
|
return -ENOMEM; |
|
|
|
if (key_type) |
|
strcpy(derived_buf, "AUTH_KEY"); |
|
else |
|
strcpy(derived_buf, "ENC_KEY"); |
|
|
|
memcpy(derived_buf + strlen(derived_buf) + 1, master_key, |
|
master_keylen); |
|
ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len, |
|
derived_key); |
|
kfree_sensitive(derived_buf); |
|
return ret; |
|
} |
|
|
|
static struct skcipher_request *init_skcipher_req(const u8 *key, |
|
unsigned int key_len) |
|
{ |
|
struct skcipher_request *req; |
|
struct crypto_skcipher *tfm; |
|
int ret; |
|
|
|
tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); |
|
if (IS_ERR(tfm)) { |
|
pr_err("encrypted_key: failed to load %s transform (%ld)\n", |
|
blkcipher_alg, PTR_ERR(tfm)); |
|
return ERR_CAST(tfm); |
|
} |
|
|
|
ret = crypto_skcipher_setkey(tfm, key, key_len); |
|
if (ret < 0) { |
|
pr_err("encrypted_key: failed to setkey (%d)\n", ret); |
|
crypto_free_skcipher(tfm); |
|
return ERR_PTR(ret); |
|
} |
|
|
|
req = skcipher_request_alloc(tfm, GFP_KERNEL); |
|
if (!req) { |
|
pr_err("encrypted_key: failed to allocate request for %s\n", |
|
blkcipher_alg); |
|
crypto_free_skcipher(tfm); |
|
return ERR_PTR(-ENOMEM); |
|
} |
|
|
|
skcipher_request_set_callback(req, 0, NULL, NULL); |
|
return req; |
|
} |
|
|
|
static struct key *request_master_key(struct encrypted_key_payload *epayload, |
|
const u8 **master_key, size_t *master_keylen) |
|
{ |
|
struct key *mkey = ERR_PTR(-EINVAL); |
|
|
|
if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, |
|
KEY_TRUSTED_PREFIX_LEN)) { |
|
mkey = request_trusted_key(epayload->master_desc + |
|
KEY_TRUSTED_PREFIX_LEN, |
|
master_key, master_keylen); |
|
} else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, |
|
KEY_USER_PREFIX_LEN)) { |
|
mkey = request_user_key(epayload->master_desc + |
|
KEY_USER_PREFIX_LEN, |
|
master_key, master_keylen); |
|
} else |
|
goto out; |
|
|
|
if (IS_ERR(mkey)) { |
|
int ret = PTR_ERR(mkey); |
|
|
|
if (ret == -ENOTSUPP) |
|
pr_info("encrypted_key: key %s not supported", |
|
epayload->master_desc); |
|
else |
|
pr_info("encrypted_key: key %s not found", |
|
epayload->master_desc); |
|
goto out; |
|
} |
|
|
|
dump_master_key(*master_key, *master_keylen); |
|
out: |
|
return mkey; |
|
} |
|
|
|
/* Before returning data to userspace, encrypt decrypted data. */ |
|
static int derived_key_encrypt(struct encrypted_key_payload *epayload, |
|
const u8 *derived_key, |
|
unsigned int derived_keylen) |
|
{ |
|
struct scatterlist sg_in[2]; |
|
struct scatterlist sg_out[1]; |
|
struct crypto_skcipher *tfm; |
|
struct skcipher_request *req; |
|
unsigned int encrypted_datalen; |
|
u8 iv[AES_BLOCK_SIZE]; |
|
int ret; |
|
|
|
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); |
|
|
|
req = init_skcipher_req(derived_key, derived_keylen); |
|
ret = PTR_ERR(req); |
|
if (IS_ERR(req)) |
|
goto out; |
|
dump_decrypted_data(epayload); |
|
|
|
sg_init_table(sg_in, 2); |
|
sg_set_buf(&sg_in[0], epayload->decrypted_data, |
|
epayload->decrypted_datalen); |
|
sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0); |
|
|
|
sg_init_table(sg_out, 1); |
|
sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); |
|
|
|
memcpy(iv, epayload->iv, sizeof(iv)); |
|
skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); |
|
ret = crypto_skcipher_encrypt(req); |
|
tfm = crypto_skcipher_reqtfm(req); |
|
skcipher_request_free(req); |
|
crypto_free_skcipher(tfm); |
|
if (ret < 0) |
|
pr_err("encrypted_key: failed to encrypt (%d)\n", ret); |
|
else |
|
dump_encrypted_data(epayload, encrypted_datalen); |
|
out: |
|
return ret; |
|
} |
|
|
|
static int datablob_hmac_append(struct encrypted_key_payload *epayload, |
|
const u8 *master_key, size_t master_keylen) |
|
{ |
|
u8 derived_key[HASH_SIZE]; |
|
u8 *digest; |
|
int ret; |
|
|
|
ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); |
|
if (ret < 0) |
|
goto out; |
|
|
|
digest = epayload->format + epayload->datablob_len; |
|
ret = calc_hmac(digest, derived_key, sizeof derived_key, |
|
epayload->format, epayload->datablob_len); |
|
if (!ret) |
|
dump_hmac(NULL, digest, HASH_SIZE); |
|
out: |
|
memzero_explicit(derived_key, sizeof(derived_key)); |
|
return ret; |
|
} |
|
|
|
/* verify HMAC before decrypting encrypted key */ |
|
static int datablob_hmac_verify(struct encrypted_key_payload *epayload, |
|
const u8 *format, const u8 *master_key, |
|
size_t master_keylen) |
|
{ |
|
u8 derived_key[HASH_SIZE]; |
|
u8 digest[HASH_SIZE]; |
|
int ret; |
|
char *p; |
|
unsigned short len; |
|
|
|
ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); |
|
if (ret < 0) |
|
goto out; |
|
|
|
len = epayload->datablob_len; |
|
if (!format) { |
|
p = epayload->master_desc; |
|
len -= strlen(epayload->format) + 1; |
|
} else |
|
p = epayload->format; |
|
|
|
ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); |
|
if (ret < 0) |
|
goto out; |
|
ret = crypto_memneq(digest, epayload->format + epayload->datablob_len, |
|
sizeof(digest)); |
|
if (ret) { |
|
ret = -EINVAL; |
|
dump_hmac("datablob", |
|
epayload->format + epayload->datablob_len, |
|
HASH_SIZE); |
|
dump_hmac("calc", digest, HASH_SIZE); |
|
} |
|
out: |
|
memzero_explicit(derived_key, sizeof(derived_key)); |
|
return ret; |
|
} |
|
|
|
static int derived_key_decrypt(struct encrypted_key_payload *epayload, |
|
const u8 *derived_key, |
|
unsigned int derived_keylen) |
|
{ |
|
struct scatterlist sg_in[1]; |
|
struct scatterlist sg_out[2]; |
|
struct crypto_skcipher *tfm; |
|
struct skcipher_request *req; |
|
unsigned int encrypted_datalen; |
|
u8 iv[AES_BLOCK_SIZE]; |
|
u8 *pad; |
|
int ret; |
|
|
|
/* Throwaway buffer to hold the unused zero padding at the end */ |
|
pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL); |
|
if (!pad) |
|
return -ENOMEM; |
|
|
|
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); |
|
req = init_skcipher_req(derived_key, derived_keylen); |
|
ret = PTR_ERR(req); |
|
if (IS_ERR(req)) |
|
goto out; |
|
dump_encrypted_data(epayload, encrypted_datalen); |
|
|
|
sg_init_table(sg_in, 1); |
|
sg_init_table(sg_out, 2); |
|
sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); |
|
sg_set_buf(&sg_out[0], epayload->decrypted_data, |
|
epayload->decrypted_datalen); |
|
sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE); |
|
|
|
memcpy(iv, epayload->iv, sizeof(iv)); |
|
skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv); |
|
ret = crypto_skcipher_decrypt(req); |
|
tfm = crypto_skcipher_reqtfm(req); |
|
skcipher_request_free(req); |
|
crypto_free_skcipher(tfm); |
|
if (ret < 0) |
|
goto out; |
|
dump_decrypted_data(epayload); |
|
out: |
|
kfree(pad); |
|
return ret; |
|
} |
|
|
|
/* Allocate memory for decrypted key and datablob. */ |
|
static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, |
|
const char *format, |
|
const char *master_desc, |
|
const char *datalen) |
|
{ |
|
struct encrypted_key_payload *epayload = NULL; |
|
unsigned short datablob_len; |
|
unsigned short decrypted_datalen; |
|
unsigned short payload_datalen; |
|
unsigned int encrypted_datalen; |
|
unsigned int format_len; |
|
long dlen; |
|
int ret; |
|
|
|
ret = kstrtol(datalen, 10, &dlen); |
|
if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) |
|
return ERR_PTR(-EINVAL); |
|
|
|
format_len = (!format) ? strlen(key_format_default) : strlen(format); |
|
decrypted_datalen = dlen; |
|
payload_datalen = decrypted_datalen; |
|
if (format) { |
|
if (!strcmp(format, key_format_ecryptfs)) { |
|
if (dlen != ECRYPTFS_MAX_KEY_BYTES) { |
|
pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n", |
|
ECRYPTFS_MAX_KEY_BYTES); |
|
return ERR_PTR(-EINVAL); |
|
} |
|
decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; |
|
payload_datalen = sizeof(struct ecryptfs_auth_tok); |
|
} else if (!strcmp(format, key_format_enc32)) { |
|
if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) { |
|
pr_err("encrypted_key: enc32 key payload incorrect length: %d\n", |
|
decrypted_datalen); |
|
return ERR_PTR(-EINVAL); |
|
} |
|
} |
|
} |
|
|
|
encrypted_datalen = roundup(decrypted_datalen, blksize); |
|
|
|
datablob_len = format_len + 1 + strlen(master_desc) + 1 |
|
+ strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; |
|
|
|
ret = key_payload_reserve(key, payload_datalen + datablob_len |
|
+ HASH_SIZE + 1); |
|
if (ret < 0) |
|
return ERR_PTR(ret); |
|
|
|
epayload = kzalloc(sizeof(*epayload) + payload_datalen + |
|
datablob_len + HASH_SIZE + 1, GFP_KERNEL); |
|
if (!epayload) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
epayload->payload_datalen = payload_datalen; |
|
epayload->decrypted_datalen = decrypted_datalen; |
|
epayload->datablob_len = datablob_len; |
|
return epayload; |
|
} |
|
|
|
static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, |
|
const char *format, const char *hex_encoded_iv) |
|
{ |
|
struct key *mkey; |
|
u8 derived_key[HASH_SIZE]; |
|
const u8 *master_key; |
|
u8 *hmac; |
|
const char *hex_encoded_data; |
|
unsigned int encrypted_datalen; |
|
size_t master_keylen; |
|
size_t asciilen; |
|
int ret; |
|
|
|
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); |
|
asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; |
|
if (strlen(hex_encoded_iv) != asciilen) |
|
return -EINVAL; |
|
|
|
hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; |
|
ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize); |
|
if (ret < 0) |
|
return -EINVAL; |
|
ret = hex2bin(epayload->encrypted_data, hex_encoded_data, |
|
encrypted_datalen); |
|
if (ret < 0) |
|
return -EINVAL; |
|
|
|
hmac = epayload->format + epayload->datablob_len; |
|
ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), |
|
HASH_SIZE); |
|
if (ret < 0) |
|
return -EINVAL; |
|
|
|
mkey = request_master_key(epayload, &master_key, &master_keylen); |
|
if (IS_ERR(mkey)) |
|
return PTR_ERR(mkey); |
|
|
|
ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); |
|
if (ret < 0) { |
|
pr_err("encrypted_key: bad hmac (%d)\n", ret); |
|
goto out; |
|
} |
|
|
|
ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); |
|
if (ret < 0) |
|
goto out; |
|
|
|
ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); |
|
if (ret < 0) |
|
pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); |
|
out: |
|
up_read(&mkey->sem); |
|
key_put(mkey); |
|
memzero_explicit(derived_key, sizeof(derived_key)); |
|
return ret; |
|
} |
|
|
|
static void __ekey_init(struct encrypted_key_payload *epayload, |
|
const char *format, const char *master_desc, |
|
const char *datalen) |
|
{ |
|
unsigned int format_len; |
|
|
|
format_len = (!format) ? strlen(key_format_default) : strlen(format); |
|
epayload->format = epayload->payload_data + epayload->payload_datalen; |
|
epayload->master_desc = epayload->format + format_len + 1; |
|
epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; |
|
epayload->iv = epayload->datalen + strlen(datalen) + 1; |
|
epayload->encrypted_data = epayload->iv + ivsize + 1; |
|
epayload->decrypted_data = epayload->payload_data; |
|
|
|
if (!format) |
|
memcpy(epayload->format, key_format_default, format_len); |
|
else { |
|
if (!strcmp(format, key_format_ecryptfs)) |
|
epayload->decrypted_data = |
|
ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); |
|
|
|
memcpy(epayload->format, format, format_len); |
|
} |
|
|
|
memcpy(epayload->master_desc, master_desc, strlen(master_desc)); |
|
memcpy(epayload->datalen, datalen, strlen(datalen)); |
|
} |
|
|
|
/* |
|
* encrypted_init - initialize an encrypted key |
|
* |
|
* For a new key, use a random number for both the iv and data |
|
* itself. For an old key, decrypt the hex encoded data. |
|
*/ |
|
static int encrypted_init(struct encrypted_key_payload *epayload, |
|
const char *key_desc, const char *format, |
|
const char *master_desc, const char *datalen, |
|
const char *hex_encoded_iv) |
|
{ |
|
int ret = 0; |
|
|
|
if (format && !strcmp(format, key_format_ecryptfs)) { |
|
ret = valid_ecryptfs_desc(key_desc); |
|
if (ret < 0) |
|
return ret; |
|
|
|
ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, |
|
key_desc); |
|
} |
|
|
|
__ekey_init(epayload, format, master_desc, datalen); |
|
if (!hex_encoded_iv) { |
|
get_random_bytes(epayload->iv, ivsize); |
|
|
|
get_random_bytes(epayload->decrypted_data, |
|
epayload->decrypted_datalen); |
|
} else |
|
ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); |
|
return ret; |
|
} |
|
|
|
/* |
|
* encrypted_instantiate - instantiate an encrypted key |
|
* |
|
* Decrypt an existing encrypted datablob or create a new encrypted key |
|
* based on a kernel random number. |
|
* |
|
* On success, return 0. Otherwise return errno. |
|
*/ |
|
static int encrypted_instantiate(struct key *key, |
|
struct key_preparsed_payload *prep) |
|
{ |
|
struct encrypted_key_payload *epayload = NULL; |
|
char *datablob = NULL; |
|
const char *format = NULL; |
|
char *master_desc = NULL; |
|
char *decrypted_datalen = NULL; |
|
char *hex_encoded_iv = NULL; |
|
size_t datalen = prep->datalen; |
|
int ret; |
|
|
|
if (datalen <= 0 || datalen > 32767 || !prep->data) |
|
return -EINVAL; |
|
|
|
datablob = kmalloc(datalen + 1, GFP_KERNEL); |
|
if (!datablob) |
|
return -ENOMEM; |
|
datablob[datalen] = 0; |
|
memcpy(datablob, prep->data, datalen); |
|
ret = datablob_parse(datablob, &format, &master_desc, |
|
&decrypted_datalen, &hex_encoded_iv); |
|
if (ret < 0) |
|
goto out; |
|
|
|
epayload = encrypted_key_alloc(key, format, master_desc, |
|
decrypted_datalen); |
|
if (IS_ERR(epayload)) { |
|
ret = PTR_ERR(epayload); |
|
goto out; |
|
} |
|
ret = encrypted_init(epayload, key->description, format, master_desc, |
|
decrypted_datalen, hex_encoded_iv); |
|
if (ret < 0) { |
|
kfree_sensitive(epayload); |
|
goto out; |
|
} |
|
|
|
rcu_assign_keypointer(key, epayload); |
|
out: |
|
kfree_sensitive(datablob); |
|
return ret; |
|
} |
|
|
|
static void encrypted_rcu_free(struct rcu_head *rcu) |
|
{ |
|
struct encrypted_key_payload *epayload; |
|
|
|
epayload = container_of(rcu, struct encrypted_key_payload, rcu); |
|
kfree_sensitive(epayload); |
|
} |
|
|
|
/* |
|
* encrypted_update - update the master key description |
|
* |
|
* Change the master key description for an existing encrypted key. |
|
* The next read will return an encrypted datablob using the new |
|
* master key description. |
|
* |
|
* On success, return 0. Otherwise return errno. |
|
*/ |
|
static int encrypted_update(struct key *key, struct key_preparsed_payload *prep) |
|
{ |
|
struct encrypted_key_payload *epayload = key->payload.data[0]; |
|
struct encrypted_key_payload *new_epayload; |
|
char *buf; |
|
char *new_master_desc = NULL; |
|
const char *format = NULL; |
|
size_t datalen = prep->datalen; |
|
int ret = 0; |
|
|
|
if (key_is_negative(key)) |
|
return -ENOKEY; |
|
if (datalen <= 0 || datalen > 32767 || !prep->data) |
|
return -EINVAL; |
|
|
|
buf = kmalloc(datalen + 1, GFP_KERNEL); |
|
if (!buf) |
|
return -ENOMEM; |
|
|
|
buf[datalen] = 0; |
|
memcpy(buf, prep->data, datalen); |
|
ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); |
|
if (ret < 0) |
|
goto out; |
|
|
|
ret = valid_master_desc(new_master_desc, epayload->master_desc); |
|
if (ret < 0) |
|
goto out; |
|
|
|
new_epayload = encrypted_key_alloc(key, epayload->format, |
|
new_master_desc, epayload->datalen); |
|
if (IS_ERR(new_epayload)) { |
|
ret = PTR_ERR(new_epayload); |
|
goto out; |
|
} |
|
|
|
__ekey_init(new_epayload, epayload->format, new_master_desc, |
|
epayload->datalen); |
|
|
|
memcpy(new_epayload->iv, epayload->iv, ivsize); |
|
memcpy(new_epayload->payload_data, epayload->payload_data, |
|
epayload->payload_datalen); |
|
|
|
rcu_assign_keypointer(key, new_epayload); |
|
call_rcu(&epayload->rcu, encrypted_rcu_free); |
|
out: |
|
kfree_sensitive(buf); |
|
return ret; |
|
} |
|
|
|
/* |
|
* encrypted_read - format and copy out the encrypted data |
|
* |
|
* The resulting datablob format is: |
|
* <master-key name> <decrypted data length> <encrypted iv> <encrypted data> |
|
* |
|
* On success, return to userspace the encrypted key datablob size. |
|
*/ |
|
static long encrypted_read(const struct key *key, char *buffer, |
|
size_t buflen) |
|
{ |
|
struct encrypted_key_payload *epayload; |
|
struct key *mkey; |
|
const u8 *master_key; |
|
size_t master_keylen; |
|
char derived_key[HASH_SIZE]; |
|
char *ascii_buf; |
|
size_t asciiblob_len; |
|
int ret; |
|
|
|
epayload = dereference_key_locked(key); |
|
|
|
/* returns the hex encoded iv, encrypted-data, and hmac as ascii */ |
|
asciiblob_len = epayload->datablob_len + ivsize + 1 |
|
+ roundup(epayload->decrypted_datalen, blksize) |
|
+ (HASH_SIZE * 2); |
|
|
|
if (!buffer || buflen < asciiblob_len) |
|
return asciiblob_len; |
|
|
|
mkey = request_master_key(epayload, &master_key, &master_keylen); |
|
if (IS_ERR(mkey)) |
|
return PTR_ERR(mkey); |
|
|
|
ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); |
|
if (ret < 0) |
|
goto out; |
|
|
|
ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); |
|
if (ret < 0) |
|
goto out; |
|
|
|
ret = datablob_hmac_append(epayload, master_key, master_keylen); |
|
if (ret < 0) |
|
goto out; |
|
|
|
ascii_buf = datablob_format(epayload, asciiblob_len); |
|
if (!ascii_buf) { |
|
ret = -ENOMEM; |
|
goto out; |
|
} |
|
|
|
up_read(&mkey->sem); |
|
key_put(mkey); |
|
memzero_explicit(derived_key, sizeof(derived_key)); |
|
|
|
memcpy(buffer, ascii_buf, asciiblob_len); |
|
kfree_sensitive(ascii_buf); |
|
|
|
return asciiblob_len; |
|
out: |
|
up_read(&mkey->sem); |
|
key_put(mkey); |
|
memzero_explicit(derived_key, sizeof(derived_key)); |
|
return ret; |
|
} |
|
|
|
/* |
|
* encrypted_destroy - clear and free the key's payload |
|
*/ |
|
static void encrypted_destroy(struct key *key) |
|
{ |
|
kfree_sensitive(key->payload.data[0]); |
|
} |
|
|
|
struct key_type key_type_encrypted = { |
|
.name = "encrypted", |
|
.instantiate = encrypted_instantiate, |
|
.update = encrypted_update, |
|
.destroy = encrypted_destroy, |
|
.describe = user_describe, |
|
.read = encrypted_read, |
|
}; |
|
EXPORT_SYMBOL_GPL(key_type_encrypted); |
|
|
|
static int __init init_encrypted(void) |
|
{ |
|
int ret; |
|
|
|
hash_tfm = crypto_alloc_shash(hash_alg, 0, 0); |
|
if (IS_ERR(hash_tfm)) { |
|
pr_err("encrypted_key: can't allocate %s transform: %ld\n", |
|
hash_alg, PTR_ERR(hash_tfm)); |
|
return PTR_ERR(hash_tfm); |
|
} |
|
|
|
ret = aes_get_sizes(); |
|
if (ret < 0) |
|
goto out; |
|
ret = register_key_type(&key_type_encrypted); |
|
if (ret < 0) |
|
goto out; |
|
return 0; |
|
out: |
|
crypto_free_shash(hash_tfm); |
|
return ret; |
|
|
|
} |
|
|
|
static void __exit cleanup_encrypted(void) |
|
{ |
|
crypto_free_shash(hash_tfm); |
|
unregister_key_type(&key_type_encrypted); |
|
} |
|
|
|
late_initcall(init_encrypted); |
|
module_exit(cleanup_encrypted); |
|
|
|
MODULE_LICENSE("GPL");
|
|
|