keys: add new key-type encrypted
Define a new kernel key-type called 'encrypted'. Encrypted keys are kernel generated random numbers, which are encrypted/decrypted with a 'trusted' symmetric key. Encrypted keys are created/encrypted/decrypted in the kernel. Userspace only ever sees/stores encrypted blobs. Changelog: - bug fix: replaced master-key rcu based locking with semaphore (reported by David Howells) - Removed memset of crypto_shash_digest() digest output - Replaced verification of 'key-type:key-desc' using strcspn(), with one based on string constants. - Moved documentation to Documentation/keys-trusted-encrypted.txt - Replace hash with shash (based on comments by David Howells) - Make lengths/counts size_t where possible (based on comments by David Howells) Could not convert most lengths, as crypto expects 'unsigned int' (size_t: on 32 bit is defined as unsigned int, but on 64 bit is unsigned long) - Add 'const' where possible (based on comments by David Howells) - allocate derived_buf dynamically to support arbitrary length master key (fixed by Roberto Sassu) - wait until late_initcall for crypto libraries to be registered - cleanup security/Kconfig - Add missing 'update' keyword (reported/fixed by Roberto Sassu) - Free epayload on failure to create key (reported/fixed by Roberto Sassu) - Increase the data size limit (requested by Roberto Sassu) - Crypto return codes are always 0 on success and negative on failure, remove unnecessary tests. - Replaced kzalloc() with kmalloc() Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Signed-off-by: David Safford <safford@watson.ibm.com> Reviewed-by: Roberto Sassu <roberto.sassu@polito.it> Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Mimi Zohar
James Morris
Родитель
d00a1c72f7
Коммит
7e70cb4978
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@ -0,0 +1,29 @@
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/*
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* Copyright (C) 2010 IBM Corporation
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* Author: Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2 of the License.
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*/
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#ifndef _KEYS_ENCRYPTED_TYPE_H
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#define _KEYS_ENCRYPTED_TYPE_H
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#include <linux/key.h>
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#include <linux/rcupdate.h>
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struct encrypted_key_payload {
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struct rcu_head rcu;
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char *master_desc; /* datablob: master key name */
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char *datalen; /* datablob: decrypted key length */
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u8 *iv; /* datablob: iv */
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u8 *encrypted_data; /* datablob: encrypted data */
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unsigned short datablob_len; /* length of datablob */
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unsigned short decrypted_datalen; /* decrypted data length */
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u8 decrypted_data[0]; /* decrypted data + datablob + hmac */
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};
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extern struct key_type key_type_encrypted;
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#endif /* _KEYS_ENCRYPTED_TYPE_H */
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@ -36,6 +36,22 @@ config TRUSTED_KEYS
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If you are unsure as to whether this is required, answer N.
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config ENCRYPTED_KEYS
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tristate "ENCRYPTED KEYS"
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depends on KEYS && TRUSTED_KEYS
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select CRYPTO_AES
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select CRYPTO_CBC
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select CRYPTO_SHA256
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select CRYPTO_RNG
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help
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This option provides support for create/encrypting/decrypting keys
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in the kernel. Encrypted keys are kernel generated random numbers,
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which are encrypted/decrypted with a 'master' symmetric key. The
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'master' key can be either a trusted-key or user-key type.
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Userspace only ever sees/stores encrypted blobs.
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If you are unsure as to whether this is required, answer N.
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config KEYS_DEBUG_PROC_KEYS
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bool "Enable the /proc/keys file by which keys may be viewed"
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depends on KEYS
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@ -14,6 +14,7 @@ obj-y := \
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user_defined.o
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obj-$(CONFIG_TRUSTED_KEYS) += trusted_defined.o
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obj-$(CONFIG_ENCRYPTED_KEYS) += encrypted_defined.o
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obj-$(CONFIG_KEYS_COMPAT) += compat.o
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obj-$(CONFIG_PROC_FS) += proc.o
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obj-$(CONFIG_SYSCTL) += sysctl.o
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@ -0,0 +1,907 @@
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/*
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* Copyright (C) 2010 IBM Corporation
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*
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* Author:
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* Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2 of the License.
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*
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* See Documentation/keys-trusted-encrypted.txt
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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 <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/crypto.h>
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#include <crypto/hash.h>
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#include <crypto/sha.h>
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#include <crypto/aes.h>
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#include "encrypted_defined.h"
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#define KEY_TRUSTED_PREFIX "trusted:"
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#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
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#define KEY_USER_PREFIX "user:"
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#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
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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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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 unsigned int ivsize;
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static int blksize;
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struct sdesc {
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struct shash_desc shash;
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char ctx[];
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};
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static struct crypto_shash *hashalg;
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static struct crypto_shash *hmacalg;
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enum {
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Opt_err = -1, Opt_new, Opt_load, Opt_update
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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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static int aes_get_sizes(void)
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{
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struct crypto_blkcipher *tfm;
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tfm = crypto_alloc_blkcipher(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_blkcipher_ivsize(tfm);
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blksize = crypto_blkcipher_blocksize(tfm);
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crypto_free_blkcipher(tfm);
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return 0;
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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:" | "encrypted:"
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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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if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
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if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
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goto out;
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if (orig_desc)
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if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
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goto out;
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} else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
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if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
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goto out;
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if (orig_desc)
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if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
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goto out;
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} else
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goto out;
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return 0;
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out:
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return -EINVAL;
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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 <master-key name> <decrypted data length>
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* load <master-key name> <decrypted data length> <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, char **master_desc,
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char **decrypted_datalen, char **hex_encoded_iv,
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char **hex_encoded_data)
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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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char *p;
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p = strsep(&datablob, " \t");
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if (!p)
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return ret;
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key_cmd = match_token(p, key_tokens, args);
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*master_desc = strsep(&datablob, " \t");
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if (!*master_desc)
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goto out;
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if (valid_master_desc(*master_desc, NULL) < 0)
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goto out;
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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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goto out;
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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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break;
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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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break;
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*hex_encoded_iv = strsep(&datablob, " \t");
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if (!*hex_encoded_iv)
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break;
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*hex_encoded_data = *hex_encoded_iv + (2 * ivsize) + 2;
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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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break;
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ret = 0;
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break;
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case Opt_err:
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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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* 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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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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ascii_buf[asciiblob_len] = '\0';
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/* copy datablob master_desc and datalen strings */
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len = sprintf(ascii_buf, "%s %s ", epayload->master_desc,
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epayload->datalen);
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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 = pack_hex_byte(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_trusted_key - request the trusted key
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*
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* Trusted keys are sealed to PCRs and other metadata. Although userspace
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* manages both trusted/encrypted key-types, like the encrypted key type
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* data, trusted key type data is not visible decrypted from userspace.
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*/
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static struct key *request_trusted_key(const char *trusted_desc,
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u8 **master_key,
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unsigned int *master_keylen)
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{
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struct trusted_key_payload *tpayload;
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struct key *tkey;
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tkey = request_key(&key_type_trusted, trusted_desc, NULL);
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if (IS_ERR(tkey))
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goto error;
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down_read(&tkey->sem);
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tpayload = rcu_dereference(tkey->payload.data);
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*master_key = tpayload->key;
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*master_keylen = tpayload->key_len;
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error:
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return tkey;
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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, u8 **master_key,
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unsigned int *master_keylen)
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{
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struct user_key_payload *upayload;
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struct key *ukey;
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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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down_read(&ukey->sem);
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upayload = rcu_dereference(ukey->payload.data);
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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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static struct sdesc *init_sdesc(struct crypto_shash *alg)
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{
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struct sdesc *sdesc;
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int size;
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size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
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sdesc = kmalloc(size, GFP_KERNEL);
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if (!sdesc)
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return ERR_PTR(-ENOMEM);
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sdesc->shash.tfm = alg;
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sdesc->shash.flags = 0x0;
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return sdesc;
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}
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static int calc_hmac(u8 *digest, const u8 *key, const unsigned int keylen,
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const u8 *buf, const unsigned int buflen)
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{
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struct sdesc *sdesc;
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int ret;
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sdesc = init_sdesc(hmacalg);
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if (IS_ERR(sdesc)) {
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pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
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return PTR_ERR(sdesc);
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}
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ret = crypto_shash_setkey(hmacalg, key, keylen);
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if (!ret)
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ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
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kfree(sdesc);
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return ret;
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}
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static int calc_hash(u8 *digest, const u8 *buf, const unsigned int buflen)
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{
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struct sdesc *sdesc;
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int ret;
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sdesc = init_sdesc(hashalg);
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if (IS_ERR(sdesc)) {
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pr_info("encrypted_key: can't alloc %s\n", hash_alg);
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return PTR_ERR(sdesc);
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}
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ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
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kfree(sdesc);
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return ret;
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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,
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const unsigned int master_keylen)
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{
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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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|
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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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|
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derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
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if (!derived_buf) {
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pr_err("encrypted_key: out of memory\n");
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return -ENOMEM;
|
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}
|
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if (key_type)
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strcpy(derived_buf, "AUTH_KEY");
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else
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strcpy(derived_buf, "ENC_KEY");
|
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|
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memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
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master_keylen);
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ret = calc_hash(derived_key, derived_buf, derived_buf_len);
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kfree(derived_buf);
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return ret;
|
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}
|
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|
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static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
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const unsigned int key_len, const u8 *iv,
|
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const unsigned int ivsize)
|
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{
|
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int ret;
|
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|
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desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
|
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if (IS_ERR(desc->tfm)) {
|
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pr_err("encrypted_key: failed to load %s transform (%ld)\n",
|
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blkcipher_alg, PTR_ERR(desc->tfm));
|
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return PTR_ERR(desc->tfm);
|
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}
|
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desc->flags = 0;
|
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|
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ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
|
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if (ret < 0) {
|
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pr_err("encrypted_key: failed to setkey (%d)\n", ret);
|
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crypto_free_blkcipher(desc->tfm);
|
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return ret;
|
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}
|
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crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
|
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return 0;
|
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}
|
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|
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static struct key *request_master_key(struct encrypted_key_payload *epayload,
|
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u8 **master_key,
|
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unsigned int *master_keylen)
|
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{
|
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struct key *mkey = NULL;
|
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|
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if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
|
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KEY_TRUSTED_PREFIX_LEN)) {
|
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mkey = request_trusted_key(epayload->master_desc +
|
||||
KEY_TRUSTED_PREFIX_LEN,
|
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master_key, master_keylen);
|
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} else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
|
||||
KEY_USER_PREFIX_LEN)) {
|
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mkey = request_user_key(epayload->master_desc +
|
||||
KEY_USER_PREFIX_LEN,
|
||||
master_key, master_keylen);
|
||||
} else
|
||||
goto out;
|
||||
|
||||
if (IS_ERR(mkey))
|
||||
pr_info("encrypted_key: key %s not found",
|
||||
epayload->master_desc);
|
||||
if (mkey)
|
||||
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,
|
||||
const unsigned int derived_keylen)
|
||||
{
|
||||
struct scatterlist sg_in[2];
|
||||
struct scatterlist sg_out[1];
|
||||
struct blkcipher_desc desc;
|
||||
unsigned int encrypted_datalen;
|
||||
unsigned int padlen;
|
||||
char pad[16];
|
||||
int ret;
|
||||
|
||||
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
|
||||
padlen = encrypted_datalen - epayload->decrypted_datalen;
|
||||
|
||||
ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
|
||||
epayload->iv, ivsize);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
dump_decrypted_data(epayload);
|
||||
|
||||
memset(pad, 0, sizeof pad);
|
||||
sg_init_table(sg_in, 2);
|
||||
sg_set_buf(&sg_in[0], epayload->decrypted_data,
|
||||
epayload->decrypted_datalen);
|
||||
sg_set_buf(&sg_in[1], pad, padlen);
|
||||
|
||||
sg_init_table(sg_out, 1);
|
||||
sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
|
||||
|
||||
ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
|
||||
crypto_free_blkcipher(desc.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,
|
||||
const unsigned int 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->master_desc + epayload->datablob_len;
|
||||
ret = calc_hmac(digest, derived_key, sizeof derived_key,
|
||||
epayload->master_desc, epayload->datablob_len);
|
||||
if (!ret)
|
||||
dump_hmac(NULL, digest, HASH_SIZE);
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
/* verify HMAC before decrypting encrypted key */
|
||||
static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
|
||||
const u8 *master_key,
|
||||
const unsigned int master_keylen)
|
||||
{
|
||||
u8 derived_key[HASH_SIZE];
|
||||
u8 digest[HASH_SIZE];
|
||||
int ret;
|
||||
|
||||
ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
|
||||
ret = calc_hmac(digest, derived_key, sizeof derived_key,
|
||||
epayload->master_desc, epayload->datablob_len);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
ret = memcmp(digest, epayload->master_desc + epayload->datablob_len,
|
||||
sizeof digest);
|
||||
if (ret) {
|
||||
ret = -EINVAL;
|
||||
dump_hmac("datablob",
|
||||
epayload->master_desc + epayload->datablob_len,
|
||||
HASH_SIZE);
|
||||
dump_hmac("calc", digest, HASH_SIZE);
|
||||
}
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int derived_key_decrypt(struct encrypted_key_payload *epayload,
|
||||
const u8 *derived_key,
|
||||
const unsigned int derived_keylen)
|
||||
{
|
||||
struct scatterlist sg_in[1];
|
||||
struct scatterlist sg_out[2];
|
||||
struct blkcipher_desc desc;
|
||||
unsigned int encrypted_datalen;
|
||||
char pad[16];
|
||||
int ret;
|
||||
|
||||
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
|
||||
ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
|
||||
epayload->iv, ivsize);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
dump_encrypted_data(epayload, encrypted_datalen);
|
||||
|
||||
memset(pad, 0, sizeof pad);
|
||||
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,
|
||||
(unsigned int)epayload->decrypted_datalen);
|
||||
sg_set_buf(&sg_out[1], pad, sizeof pad);
|
||||
|
||||
ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
|
||||
crypto_free_blkcipher(desc.tfm);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
dump_decrypted_data(epayload);
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
/* Allocate memory for decrypted key and datablob. */
|
||||
static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
|
||||
const char *master_desc,
|
||||
const char *datalen)
|
||||
{
|
||||
struct encrypted_key_payload *epayload = NULL;
|
||||
unsigned short datablob_len;
|
||||
unsigned short decrypted_datalen;
|
||||
unsigned int encrypted_datalen;
|
||||
long dlen;
|
||||
int ret;
|
||||
|
||||
ret = strict_strtol(datalen, 10, &dlen);
|
||||
if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
|
||||
return ERR_PTR(-EINVAL);
|
||||
|
||||
decrypted_datalen = dlen;
|
||||
encrypted_datalen = roundup(decrypted_datalen, blksize);
|
||||
|
||||
datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1
|
||||
+ ivsize + 1 + encrypted_datalen;
|
||||
|
||||
ret = key_payload_reserve(key, decrypted_datalen + datablob_len
|
||||
+ HASH_SIZE + 1);
|
||||
if (ret < 0)
|
||||
return ERR_PTR(ret);
|
||||
|
||||
epayload = kzalloc(sizeof(*epayload) + decrypted_datalen +
|
||||
datablob_len + HASH_SIZE + 1, GFP_KERNEL);
|
||||
if (!epayload)
|
||||
return ERR_PTR(-ENOMEM);
|
||||
|
||||
epayload->decrypted_datalen = decrypted_datalen;
|
||||
epayload->datablob_len = datablob_len;
|
||||
return epayload;
|
||||
}
|
||||
|
||||
static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
|
||||
const char *hex_encoded_iv,
|
||||
const char *hex_encoded_data)
|
||||
{
|
||||
struct key *mkey;
|
||||
u8 derived_key[HASH_SIZE];
|
||||
u8 *master_key;
|
||||
u8 *hmac;
|
||||
unsigned int master_keylen;
|
||||
unsigned int encrypted_datalen;
|
||||
int ret;
|
||||
|
||||
encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
|
||||
hex2bin(epayload->iv, hex_encoded_iv, ivsize);
|
||||
hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen);
|
||||
|
||||
hmac = epayload->master_desc + epayload->datablob_len;
|
||||
hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE);
|
||||
|
||||
mkey = request_master_key(epayload, &master_key, &master_keylen);
|
||||
if (IS_ERR(mkey))
|
||||
return PTR_ERR(mkey);
|
||||
|
||||
ret = datablob_hmac_verify(epayload, 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);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static void __ekey_init(struct encrypted_key_payload *epayload,
|
||||
const char *master_desc, const char *datalen)
|
||||
{
|
||||
epayload->master_desc = epayload->decrypted_data
|
||||
+ epayload->decrypted_datalen;
|
||||
epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
|
||||
epayload->iv = epayload->datalen + strlen(datalen) + 1;
|
||||
epayload->encrypted_data = epayload->iv + ivsize + 1;
|
||||
|
||||
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 *master_desc, const char *datalen,
|
||||
const char *hex_encoded_iv,
|
||||
const char *hex_encoded_data)
|
||||
{
|
||||
int ret = 0;
|
||||
|
||||
__ekey_init(epayload, master_desc, datalen);
|
||||
if (!hex_encoded_data) {
|
||||
get_random_bytes(epayload->iv, ivsize);
|
||||
|
||||
get_random_bytes(epayload->decrypted_data,
|
||||
epayload->decrypted_datalen);
|
||||
} else
|
||||
ret = encrypted_key_decrypt(epayload, hex_encoded_iv,
|
||||
hex_encoded_data);
|
||||
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, const void *data,
|
||||
size_t datalen)
|
||||
{
|
||||
struct encrypted_key_payload *epayload = NULL;
|
||||
char *datablob = NULL;
|
||||
char *master_desc = NULL;
|
||||
char *decrypted_datalen = NULL;
|
||||
char *hex_encoded_iv = NULL;
|
||||
char *hex_encoded_data = NULL;
|
||||
int ret;
|
||||
|
||||
if (datalen <= 0 || datalen > 32767 || !data)
|
||||
return -EINVAL;
|
||||
|
||||
datablob = kmalloc(datalen + 1, GFP_KERNEL);
|
||||
if (!datablob)
|
||||
return -ENOMEM;
|
||||
datablob[datalen] = 0;
|
||||
memcpy(datablob, data, datalen);
|
||||
ret = datablob_parse(datablob, &master_desc, &decrypted_datalen,
|
||||
&hex_encoded_iv, &hex_encoded_data);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
|
||||
epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen);
|
||||
if (IS_ERR(epayload)) {
|
||||
ret = PTR_ERR(epayload);
|
||||
goto out;
|
||||
}
|
||||
ret = encrypted_init(epayload, master_desc, decrypted_datalen,
|
||||
hex_encoded_iv, hex_encoded_data);
|
||||
if (ret < 0) {
|
||||
kfree(epayload);
|
||||
goto out;
|
||||
}
|
||||
|
||||
rcu_assign_pointer(key->payload.data, epayload);
|
||||
out:
|
||||
kfree(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);
|
||||
memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
|
||||
kfree(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, const void *data, size_t datalen)
|
||||
{
|
||||
struct encrypted_key_payload *epayload = key->payload.data;
|
||||
struct encrypted_key_payload *new_epayload;
|
||||
char *buf;
|
||||
char *new_master_desc = NULL;
|
||||
int ret = 0;
|
||||
|
||||
if (datalen <= 0 || datalen > 32767 || !data)
|
||||
return -EINVAL;
|
||||
|
||||
buf = kmalloc(datalen + 1, GFP_KERNEL);
|
||||
if (!buf)
|
||||
return -ENOMEM;
|
||||
|
||||
buf[datalen] = 0;
|
||||
memcpy(buf, data, datalen);
|
||||
ret = datablob_parse(buf, &new_master_desc, NULL, 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, new_master_desc,
|
||||
epayload->datalen);
|
||||
if (IS_ERR(new_epayload)) {
|
||||
ret = PTR_ERR(new_epayload);
|
||||
goto out;
|
||||
}
|
||||
|
||||
__ekey_init(new_epayload, new_master_desc, epayload->datalen);
|
||||
|
||||
memcpy(new_epayload->iv, epayload->iv, ivsize);
|
||||
memcpy(new_epayload->decrypted_data, epayload->decrypted_data,
|
||||
epayload->decrypted_datalen);
|
||||
|
||||
rcu_assign_pointer(key->payload.data, new_epayload);
|
||||
call_rcu(&epayload->rcu, encrypted_rcu_free);
|
||||
out:
|
||||
kfree(buf);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* encrypted_read - format and copy the encrypted data to userspace
|
||||
*
|
||||
* 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 __user *buffer,
|
||||
size_t buflen)
|
||||
{
|
||||
struct encrypted_key_payload *epayload;
|
||||
struct key *mkey;
|
||||
u8 *master_key;
|
||||
unsigned int master_keylen;
|
||||
char derived_key[HASH_SIZE];
|
||||
char *ascii_buf;
|
||||
size_t asciiblob_len;
|
||||
int ret;
|
||||
|
||||
epayload = rcu_dereference_protected(key->payload.data,
|
||||
rwsem_is_locked(&((struct key *)key)->sem));
|
||||
|
||||
/* 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);
|
||||
|
||||
if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
|
||||
ret = -EFAULT;
|
||||
kfree(ascii_buf);
|
||||
|
||||
return asciiblob_len;
|
||||
out:
|
||||
up_read(&mkey->sem);
|
||||
key_put(mkey);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* encrypted_destroy - before freeing the key, clear the decrypted data
|
||||
*
|
||||
* Before freeing the key, clear the memory containing the decrypted
|
||||
* key data.
|
||||
*/
|
||||
static void encrypted_destroy(struct key *key)
|
||||
{
|
||||
struct encrypted_key_payload *epayload = key->payload.data;
|
||||
|
||||
if (!epayload)
|
||||
return;
|
||||
|
||||
memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
|
||||
kfree(key->payload.data);
|
||||
}
|
||||
|
||||
struct key_type key_type_encrypted = {
|
||||
.name = "encrypted",
|
||||
.instantiate = encrypted_instantiate,
|
||||
.update = encrypted_update,
|
||||
.match = user_match,
|
||||
.destroy = encrypted_destroy,
|
||||
.describe = user_describe,
|
||||
.read = encrypted_read,
|
||||
};
|
||||
EXPORT_SYMBOL_GPL(key_type_encrypted);
|
||||
|
||||
static void encrypted_shash_release(void)
|
||||
{
|
||||
if (hashalg)
|
||||
crypto_free_shash(hashalg);
|
||||
if (hmacalg)
|
||||
crypto_free_shash(hmacalg);
|
||||
}
|
||||
|
||||
static int __init encrypted_shash_alloc(void)
|
||||
{
|
||||
int ret;
|
||||
|
||||
hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
|
||||
if (IS_ERR(hmacalg)) {
|
||||
pr_info("encrypted_key: could not allocate crypto %s\n",
|
||||
hmac_alg);
|
||||
return PTR_ERR(hmacalg);
|
||||
}
|
||||
|
||||
hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
|
||||
if (IS_ERR(hashalg)) {
|
||||
pr_info("encrypted_key: could not allocate crypto %s\n",
|
||||
hash_alg);
|
||||
ret = PTR_ERR(hashalg);
|
||||
goto hashalg_fail;
|
||||
}
|
||||
|
||||
return 0;
|
||||
|
||||
hashalg_fail:
|
||||
crypto_free_shash(hmacalg);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int __init init_encrypted(void)
|
||||
{
|
||||
int ret;
|
||||
|
||||
ret = encrypted_shash_alloc();
|
||||
if (ret < 0)
|
||||
return ret;
|
||||
ret = register_key_type(&key_type_encrypted);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
return aes_get_sizes();
|
||||
out:
|
||||
encrypted_shash_release();
|
||||
return ret;
|
||||
|
||||
}
|
||||
|
||||
static void __exit cleanup_encrypted(void)
|
||||
{
|
||||
encrypted_shash_release();
|
||||
unregister_key_type(&key_type_encrypted);
|
||||
}
|
||||
|
||||
late_initcall(init_encrypted);
|
||||
module_exit(cleanup_encrypted);
|
||||
|
||||
MODULE_LICENSE("GPL");
|
||||
|
|
@ -0,0 +1,56 @@
|
|||
#ifndef __ENCRYPTED_KEY_H
|
||||
#define __ENCRYPTED_KEY_H
|
||||
|
||||
#define ENCRYPTED_DEBUG 0
|
||||
|
||||
#if ENCRYPTED_DEBUG
|
||||
static inline void dump_master_key(const u8 *master_key,
|
||||
unsigned int master_keylen)
|
||||
{
|
||||
print_hex_dump(KERN_ERR, "master key: ", DUMP_PREFIX_NONE, 32, 1,
|
||||
master_key, master_keylen, 0);
|
||||
}
|
||||
|
||||
static inline void dump_decrypted_data(struct encrypted_key_payload *epayload)
|
||||
{
|
||||
print_hex_dump(KERN_ERR, "decrypted data: ", DUMP_PREFIX_NONE, 32, 1,
|
||||
epayload->decrypted_data,
|
||||
epayload->decrypted_datalen, 0);
|
||||
}
|
||||
|
||||
static inline void dump_encrypted_data(struct encrypted_key_payload *epayload,
|
||||
unsigned int encrypted_datalen)
|
||||
{
|
||||
print_hex_dump(KERN_ERR, "encrypted data: ", DUMP_PREFIX_NONE, 32, 1,
|
||||
epayload->encrypted_data, encrypted_datalen, 0);
|
||||
}
|
||||
|
||||
static inline void dump_hmac(const char *str, const u8 *digest,
|
||||
unsigned int hmac_size)
|
||||
{
|
||||
if (str)
|
||||
pr_info("encrypted_key: %s", str);
|
||||
print_hex_dump(KERN_ERR, "hmac: ", DUMP_PREFIX_NONE, 32, 1, digest,
|
||||
hmac_size, 0);
|
||||
}
|
||||
#else
|
||||
static inline void dump_master_key(const u8 *master_key,
|
||||
unsigned int master_keylen)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void dump_decrypted_data(struct encrypted_key_payload *epayload)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void dump_encrypted_data(struct encrypted_key_payload *epayload,
|
||||
unsigned int encrypted_datalen)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void dump_hmac(const char *str, const u8 *digest,
|
||||
unsigned int hmac_size)
|
||||
{
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
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Ссылка в новой задаче