forked from Minki/linux
fscrypt: move v1 policy key setup to keysetup_v1.c
In preparation for introducing v2 encryption policies which will find and derive encryption keys differently from the current v1 encryption policies, move the v1 policy-specific key setup code from keyinfo.c into keysetup_v1.c. Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers
parent
3ec4f2a629
commit
0109ce76dd
@ -1,5 +1,11 @@
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# SPDX-License-Identifier: GPL-2.0-only
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obj-$(CONFIG_FS_ENCRYPTION) += fscrypto.o
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fscrypto-y := crypto.o fname.o hooks.o keyinfo.o policy.o
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fscrypto-y := crypto.o \
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fname.o \
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hooks.o \
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keyinfo.o \
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keysetup_v1.o \
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policy.o
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fscrypto-$(CONFIG_BLOCK) += bio.o
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@ -173,4 +173,21 @@ fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
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return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
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}
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extern struct crypto_skcipher *
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fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
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const struct inode *inode);
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extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
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const u8 *derived_key);
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/* keysetup_v1.c */
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extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
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extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
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const u8 *raw_master_key);
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extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
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struct fscrypt_info *ci);
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#endif /* _FSCRYPT_PRIVATE_H */
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@ -8,130 +8,15 @@
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* Heavily modified since then.
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*/
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#include <keys/user-type.h>
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#include <linux/hashtable.h>
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#include <linux/scatterlist.h>
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#include <crypto/aes.h>
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#include <crypto/algapi.h>
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#include <crypto/sha.h>
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#include <crypto/skcipher.h>
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#include <linux/key.h>
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#include "fscrypt_private.h"
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static struct crypto_shash *essiv_hash_tfm;
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/* Table of keys referenced by DIRECT_KEY policies */
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static DEFINE_HASHTABLE(fscrypt_direct_keys, 6); /* 6 bits = 64 buckets */
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static DEFINE_SPINLOCK(fscrypt_direct_keys_lock);
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/*
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* v1 key derivation function. This generates the derived key by encrypting the
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* master key with AES-128-ECB using the nonce as the AES key. This provides a
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* unique derived key with sufficient entropy for each inode. However, it's
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* nonstandard, non-extensible, doesn't evenly distribute the entropy from the
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* master key, and is trivially reversible: an attacker who compromises a
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* derived key can "decrypt" it to get back to the master key, then derive any
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* other key. For all new code, use HKDF instead.
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*
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* The master key must be at least as long as the derived key. If the master
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* key is longer, then only the first 'derived_keysize' bytes are used.
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*/
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static int derive_key_aes(const u8 *master_key,
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const u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE],
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u8 *derived_key, unsigned int derived_keysize)
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{
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int res = 0;
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struct skcipher_request *req = NULL;
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DECLARE_CRYPTO_WAIT(wait);
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struct scatterlist src_sg, dst_sg;
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struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
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if (IS_ERR(tfm)) {
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res = PTR_ERR(tfm);
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tfm = NULL;
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goto out;
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}
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crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
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req = skcipher_request_alloc(tfm, GFP_NOFS);
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if (!req) {
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res = -ENOMEM;
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goto out;
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}
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skcipher_request_set_callback(req,
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CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
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crypto_req_done, &wait);
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res = crypto_skcipher_setkey(tfm, nonce, FS_KEY_DERIVATION_NONCE_SIZE);
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if (res < 0)
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goto out;
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sg_init_one(&src_sg, master_key, derived_keysize);
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sg_init_one(&dst_sg, derived_key, derived_keysize);
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skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
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NULL);
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res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
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out:
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skcipher_request_free(req);
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crypto_free_skcipher(tfm);
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return res;
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}
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/*
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* Search the current task's subscribed keyrings for a "logon" key with
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* description prefix:descriptor, and if found acquire a read lock on it and
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* return a pointer to its validated payload in *payload_ret.
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*/
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static struct key *
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find_and_lock_process_key(const char *prefix,
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const u8 descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE],
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unsigned int min_keysize,
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const struct fscrypt_key **payload_ret)
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{
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char *description;
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struct key *key;
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const struct user_key_payload *ukp;
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const struct fscrypt_key *payload;
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description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
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FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
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if (!description)
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return ERR_PTR(-ENOMEM);
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key = request_key(&key_type_logon, description, NULL);
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kfree(description);
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if (IS_ERR(key))
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return key;
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down_read(&key->sem);
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ukp = user_key_payload_locked(key);
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if (!ukp) /* was the key revoked before we acquired its semaphore? */
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goto invalid;
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payload = (const struct fscrypt_key *)ukp->data;
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if (ukp->datalen != sizeof(struct fscrypt_key) ||
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payload->size < 1 || payload->size > FSCRYPT_MAX_KEY_SIZE) {
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fscrypt_warn(NULL,
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"key with description '%s' has invalid payload",
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key->description);
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goto invalid;
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}
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if (payload->size < min_keysize) {
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fscrypt_warn(NULL,
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"key with description '%s' is too short (got %u bytes, need %u+ bytes)",
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key->description, payload->size, min_keysize);
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goto invalid;
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}
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*payload_ret = payload;
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return key;
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invalid:
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up_read(&key->sem);
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key_put(key);
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return ERR_PTR(-ENOKEY);
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}
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static struct fscrypt_mode available_modes[] = {
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[FSCRYPT_MODE_AES_256_XTS] = {
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.friendly_name = "AES-256-XTS",
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@ -188,9 +73,9 @@ select_encryption_mode(const struct fscrypt_info *ci, const struct inode *inode)
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}
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/* Create a symmetric cipher object for the given encryption mode and key */
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static struct crypto_skcipher *
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fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
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const struct inode *inode)
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struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode,
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const u8 *raw_key,
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const struct inode *inode)
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{
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struct crypto_skcipher *tfm;
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int err;
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@ -232,113 +117,6 @@ err_free_tfm:
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return ERR_PTR(err);
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}
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/* Master key referenced by DIRECT_KEY policy */
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struct fscrypt_direct_key {
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struct hlist_node dk_node;
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refcount_t dk_refcount;
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const struct fscrypt_mode *dk_mode;
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struct crypto_skcipher *dk_ctfm;
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u8 dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
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u8 dk_raw[FSCRYPT_MAX_KEY_SIZE];
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};
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static void free_direct_key(struct fscrypt_direct_key *dk)
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{
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if (dk) {
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crypto_free_skcipher(dk->dk_ctfm);
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kzfree(dk);
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}
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}
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static void put_direct_key(struct fscrypt_direct_key *dk)
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{
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if (!refcount_dec_and_lock(&dk->dk_refcount, &fscrypt_direct_keys_lock))
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return;
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hash_del(&dk->dk_node);
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spin_unlock(&fscrypt_direct_keys_lock);
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free_direct_key(dk);
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}
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/*
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* Find/insert the given key into the fscrypt_direct_keys table. If found, it
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* is returned with elevated refcount, and 'to_insert' is freed if non-NULL. If
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* not found, 'to_insert' is inserted and returned if it's non-NULL; otherwise
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* NULL is returned.
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*/
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static struct fscrypt_direct_key *
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find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
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const u8 *raw_key, const struct fscrypt_info *ci)
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{
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unsigned long hash_key;
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struct fscrypt_direct_key *dk;
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/*
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* Careful: to avoid potentially leaking secret key bytes via timing
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* information, we must key the hash table by descriptor rather than by
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* raw key, and use crypto_memneq() when comparing raw keys.
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*/
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BUILD_BUG_ON(sizeof(hash_key) > FSCRYPT_KEY_DESCRIPTOR_SIZE);
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memcpy(&hash_key, ci->ci_master_key_descriptor, sizeof(hash_key));
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spin_lock(&fscrypt_direct_keys_lock);
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hash_for_each_possible(fscrypt_direct_keys, dk, dk_node, hash_key) {
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if (memcmp(ci->ci_master_key_descriptor, dk->dk_descriptor,
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FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0)
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continue;
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if (ci->ci_mode != dk->dk_mode)
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continue;
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if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize))
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continue;
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/* using existing tfm with same (descriptor, mode, raw_key) */
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refcount_inc(&dk->dk_refcount);
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spin_unlock(&fscrypt_direct_keys_lock);
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free_direct_key(to_insert);
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return dk;
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}
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if (to_insert)
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hash_add(fscrypt_direct_keys, &to_insert->dk_node, hash_key);
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spin_unlock(&fscrypt_direct_keys_lock);
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return to_insert;
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}
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/* Prepare to encrypt directly using the master key in the given mode */
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static struct fscrypt_direct_key *
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fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
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{
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struct fscrypt_direct_key *dk;
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int err;
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/* Is there already a tfm for this key? */
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dk = find_or_insert_direct_key(NULL, raw_key, ci);
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if (dk)
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return dk;
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/* Nope, allocate one. */
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dk = kzalloc(sizeof(*dk), GFP_NOFS);
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if (!dk)
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return ERR_PTR(-ENOMEM);
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refcount_set(&dk->dk_refcount, 1);
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dk->dk_mode = ci->ci_mode;
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dk->dk_ctfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key,
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ci->ci_inode);
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if (IS_ERR(dk->dk_ctfm)) {
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err = PTR_ERR(dk->dk_ctfm);
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dk->dk_ctfm = NULL;
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goto err_free_dk;
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}
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memcpy(dk->dk_descriptor, ci->ci_master_key_descriptor,
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FSCRYPT_KEY_DESCRIPTOR_SIZE);
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memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize);
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return find_or_insert_direct_key(dk, raw_key, ci);
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err_free_dk:
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free_direct_key(dk);
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return ERR_PTR(err);
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}
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static int derive_essiv_salt(const u8 *key, int keysize, u8 *salt)
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{
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struct crypto_shash *tfm = READ_ONCE(essiv_hash_tfm);
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@ -409,8 +187,7 @@ out:
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}
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/* Given the per-file key, set up the file's crypto transform object(s) */
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static int fscrypt_set_derived_key(struct fscrypt_info *ci,
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const u8 *derived_key)
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int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key)
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{
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struct fscrypt_mode *mode = ci->ci_mode;
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struct crypto_skcipher *ctfm;
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@ -434,97 +211,6 @@ static int fscrypt_set_derived_key(struct fscrypt_info *ci,
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return 0;
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}
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/* v1 policy, DIRECT_KEY: use the master key directly */
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static int setup_v1_file_key_direct(struct fscrypt_info *ci,
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const u8 *raw_master_key)
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{
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const struct fscrypt_mode *mode = ci->ci_mode;
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struct fscrypt_direct_key *dk;
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if (!fscrypt_mode_supports_direct_key(mode)) {
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fscrypt_warn(ci->ci_inode,
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"Direct key mode not allowed with %s",
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mode->friendly_name);
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return -EINVAL;
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}
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if (ci->ci_data_mode != ci->ci_filename_mode) {
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fscrypt_warn(ci->ci_inode,
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"Direct key mode not allowed with different contents and filenames modes");
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return -EINVAL;
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}
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/* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
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if (WARN_ON(mode->needs_essiv))
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return -EINVAL;
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dk = fscrypt_get_direct_key(ci, raw_master_key);
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if (IS_ERR(dk))
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return PTR_ERR(dk);
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ci->ci_direct_key = dk;
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ci->ci_ctfm = dk->dk_ctfm;
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return 0;
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}
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/* v1 policy, !DIRECT_KEY: derive the file's encryption key */
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static int setup_v1_file_key_derived(struct fscrypt_info *ci,
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const u8 *raw_master_key)
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{
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u8 *derived_key;
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int err;
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/*
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* This cannot be a stack buffer because it will be passed to the
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* scatterlist crypto API during derive_key_aes().
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*/
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derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS);
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if (!derived_key)
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return -ENOMEM;
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err = derive_key_aes(raw_master_key, ci->ci_nonce,
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derived_key, ci->ci_mode->keysize);
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if (err)
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goto out;
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err = fscrypt_set_derived_key(ci, derived_key);
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out:
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kzfree(derived_key);
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return err;
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}
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static int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
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const u8 *raw_master_key)
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{
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if (ci->ci_flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
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return setup_v1_file_key_direct(ci, raw_master_key);
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else
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return setup_v1_file_key_derived(ci, raw_master_key);
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}
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static int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
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struct fscrypt_info *ci)
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{
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struct key *key;
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const struct fscrypt_key *payload;
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int err;
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key = find_and_lock_process_key(FSCRYPT_KEY_DESC_PREFIX,
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ci->ci_master_key_descriptor,
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ci->ci_mode->keysize, &payload);
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if (key == ERR_PTR(-ENOKEY) && ci->ci_inode->i_sb->s_cop->key_prefix) {
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key = find_and_lock_process_key(ci->ci_inode->i_sb->s_cop->key_prefix,
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ci->ci_master_key_descriptor,
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ci->ci_mode->keysize, &payload);
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}
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if (IS_ERR(key))
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return PTR_ERR(key);
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err = fscrypt_setup_v1_file_key(ci, payload->raw);
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up_read(&key->sem);
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key_put(key);
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return err;
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}
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/*
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* Find the master key, then set up the inode's actual encryption key.
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*/
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@ -539,7 +225,7 @@ static void put_crypt_info(struct fscrypt_info *ci)
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return;
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if (ci->ci_direct_key) {
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put_direct_key(ci->ci_direct_key);
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fscrypt_put_direct_key(ci->ci_direct_key);
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} else {
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crypto_free_skcipher(ci->ci_ctfm);
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crypto_free_cipher(ci->ci_essiv_tfm);
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338
fs/crypto/keysetup_v1.c
Normal file
338
fs/crypto/keysetup_v1.c
Normal file
@ -0,0 +1,338 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Key setup for v1 encryption policies
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*
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* Copyright 2015, 2019 Google LLC
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*/
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/*
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* This file implements compatibility functions for the original encryption
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* policy version ("v1"), including:
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*
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* - Deriving per-file keys using the AES-128-ECB based KDF
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* (rather than the new method of using HKDF-SHA512)
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*
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* - Retrieving fscrypt master keys from process-subscribed keyrings
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* (rather than the new method of using a filesystem-level keyring)
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*
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* - Handling policies with the DIRECT_KEY flag set using a master key table
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* (rather than the new method of implementing DIRECT_KEY with per-mode keys
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* managed alongside the master keys in the filesystem-level keyring)
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*/
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#include <crypto/algapi.h>
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#include <crypto/skcipher.h>
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#include <keys/user-type.h>
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#include <linux/hashtable.h>
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#include <linux/scatterlist.h>
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|
||||
#include "fscrypt_private.h"
|
||||
|
||||
/* Table of keys referenced by DIRECT_KEY policies */
|
||||
static DEFINE_HASHTABLE(fscrypt_direct_keys, 6); /* 6 bits = 64 buckets */
|
||||
static DEFINE_SPINLOCK(fscrypt_direct_keys_lock);
|
||||
|
||||
/*
|
||||
* v1 key derivation function. This generates the derived key by encrypting the
|
||||
* master key with AES-128-ECB using the nonce as the AES key. This provides a
|
||||
* unique derived key with sufficient entropy for each inode. However, it's
|
||||
* nonstandard, non-extensible, doesn't evenly distribute the entropy from the
|
||||
* master key, and is trivially reversible: an attacker who compromises a
|
||||
* derived key can "decrypt" it to get back to the master key, then derive any
|
||||
* other key. For all new code, use HKDF instead.
|
||||
*
|
||||
* The master key must be at least as long as the derived key. If the master
|
||||
* key is longer, then only the first 'derived_keysize' bytes are used.
|
||||
*/
|
||||
static int derive_key_aes(const u8 *master_key,
|
||||
const u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE],
|
||||
u8 *derived_key, unsigned int derived_keysize)
|
||||
{
|
||||
int res = 0;
|
||||
struct skcipher_request *req = NULL;
|
||||
DECLARE_CRYPTO_WAIT(wait);
|
||||
struct scatterlist src_sg, dst_sg;
|
||||
struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
|
||||
|
||||
if (IS_ERR(tfm)) {
|
||||
res = PTR_ERR(tfm);
|
||||
tfm = NULL;
|
||||
goto out;
|
||||
}
|
||||
crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
|
||||
req = skcipher_request_alloc(tfm, GFP_NOFS);
|
||||
if (!req) {
|
||||
res = -ENOMEM;
|
||||
goto out;
|
||||
}
|
||||
skcipher_request_set_callback(req,
|
||||
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
|
||||
crypto_req_done, &wait);
|
||||
res = crypto_skcipher_setkey(tfm, nonce, FS_KEY_DERIVATION_NONCE_SIZE);
|
||||
if (res < 0)
|
||||
goto out;
|
||||
|
||||
sg_init_one(&src_sg, master_key, derived_keysize);
|
||||
sg_init_one(&dst_sg, derived_key, derived_keysize);
|
||||
skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
|
||||
NULL);
|
||||
res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
|
||||
out:
|
||||
skcipher_request_free(req);
|
||||
crypto_free_skcipher(tfm);
|
||||
return res;
|
||||
}
|
||||
|
||||
/*
|
||||
* Search the current task's subscribed keyrings for a "logon" key with
|
||||
* description prefix:descriptor, and if found acquire a read lock on it and
|
||||
* return a pointer to its validated payload in *payload_ret.
|
||||
*/
|
||||
static struct key *
|
||||
find_and_lock_process_key(const char *prefix,
|
||||
const u8 descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE],
|
||||
unsigned int min_keysize,
|
||||
const struct fscrypt_key **payload_ret)
|
||||
{
|
||||
char *description;
|
||||
struct key *key;
|
||||
const struct user_key_payload *ukp;
|
||||
const struct fscrypt_key *payload;
|
||||
|
||||
description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
|
||||
FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
|
||||
if (!description)
|
||||
return ERR_PTR(-ENOMEM);
|
||||
|
||||
key = request_key(&key_type_logon, description, NULL);
|
||||
kfree(description);
|
||||
if (IS_ERR(key))
|
||||
return key;
|
||||
|
||||
down_read(&key->sem);
|
||||
ukp = user_key_payload_locked(key);
|
||||
|
||||
if (!ukp) /* was the key revoked before we acquired its semaphore? */
|
||||
goto invalid;
|
||||
|
||||
payload = (const struct fscrypt_key *)ukp->data;
|
||||
|
||||
if (ukp->datalen != sizeof(struct fscrypt_key) ||
|
||||
payload->size < 1 || payload->size > FSCRYPT_MAX_KEY_SIZE) {
|
||||
fscrypt_warn(NULL,
|
||||
"key with description '%s' has invalid payload",
|
||||
key->description);
|
||||
goto invalid;
|
||||
}
|
||||
|
||||
if (payload->size < min_keysize) {
|
||||
fscrypt_warn(NULL,
|
||||
"key with description '%s' is too short (got %u bytes, need %u+ bytes)",
|
||||
key->description, payload->size, min_keysize);
|
||||
goto invalid;
|
||||
}
|
||||
|
||||
*payload_ret = payload;
|
||||
return key;
|
||||
|
||||
invalid:
|
||||
up_read(&key->sem);
|
||||
key_put(key);
|
||||
return ERR_PTR(-ENOKEY);
|
||||
}
|
||||
|
||||
/* Master key referenced by DIRECT_KEY policy */
|
||||
struct fscrypt_direct_key {
|
||||
struct hlist_node dk_node;
|
||||
refcount_t dk_refcount;
|
||||
const struct fscrypt_mode *dk_mode;
|
||||
struct crypto_skcipher *dk_ctfm;
|
||||
u8 dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
|
||||
u8 dk_raw[FSCRYPT_MAX_KEY_SIZE];
|
||||
};
|
||||
|
||||
static void free_direct_key(struct fscrypt_direct_key *dk)
|
||||
{
|
||||
if (dk) {
|
||||
crypto_free_skcipher(dk->dk_ctfm);
|
||||
kzfree(dk);
|
||||
}
|
||||
}
|
||||
|
||||
void fscrypt_put_direct_key(struct fscrypt_direct_key *dk)
|
||||
{
|
||||
if (!refcount_dec_and_lock(&dk->dk_refcount, &fscrypt_direct_keys_lock))
|
||||
return;
|
||||
hash_del(&dk->dk_node);
|
||||
spin_unlock(&fscrypt_direct_keys_lock);
|
||||
|
||||
free_direct_key(dk);
|
||||
}
|
||||
|
||||
/*
|
||||
* Find/insert the given key into the fscrypt_direct_keys table. If found, it
|
||||
* is returned with elevated refcount, and 'to_insert' is freed if non-NULL. If
|
||||
* not found, 'to_insert' is inserted and returned if it's non-NULL; otherwise
|
||||
* NULL is returned.
|
||||
*/
|
||||
static struct fscrypt_direct_key *
|
||||
find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
|
||||
const u8 *raw_key, const struct fscrypt_info *ci)
|
||||
{
|
||||
unsigned long hash_key;
|
||||
struct fscrypt_direct_key *dk;
|
||||
|
||||
/*
|
||||
* Careful: to avoid potentially leaking secret key bytes via timing
|
||||
* information, we must key the hash table by descriptor rather than by
|
||||
* raw key, and use crypto_memneq() when comparing raw keys.
|
||||
*/
|
||||
|
||||
BUILD_BUG_ON(sizeof(hash_key) > FSCRYPT_KEY_DESCRIPTOR_SIZE);
|
||||
memcpy(&hash_key, ci->ci_master_key_descriptor, sizeof(hash_key));
|
||||
|
||||
spin_lock(&fscrypt_direct_keys_lock);
|
||||
hash_for_each_possible(fscrypt_direct_keys, dk, dk_node, hash_key) {
|
||||
if (memcmp(ci->ci_master_key_descriptor, dk->dk_descriptor,
|
||||
FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0)
|
||||
continue;
|
||||
if (ci->ci_mode != dk->dk_mode)
|
||||
continue;
|
||||
if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize))
|
||||
continue;
|
||||
/* using existing tfm with same (descriptor, mode, raw_key) */
|
||||
refcount_inc(&dk->dk_refcount);
|
||||
spin_unlock(&fscrypt_direct_keys_lock);
|
||||
free_direct_key(to_insert);
|
||||
return dk;
|
||||
}
|
||||
if (to_insert)
|
||||
hash_add(fscrypt_direct_keys, &to_insert->dk_node, hash_key);
|
||||
spin_unlock(&fscrypt_direct_keys_lock);
|
||||
return to_insert;
|
||||
}
|
||||
|
||||
/* Prepare to encrypt directly using the master key in the given mode */
|
||||
static struct fscrypt_direct_key *
|
||||
fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
|
||||
{
|
||||
struct fscrypt_direct_key *dk;
|
||||
int err;
|
||||
|
||||
/* Is there already a tfm for this key? */
|
||||
dk = find_or_insert_direct_key(NULL, raw_key, ci);
|
||||
if (dk)
|
||||
return dk;
|
||||
|
||||
/* Nope, allocate one. */
|
||||
dk = kzalloc(sizeof(*dk), GFP_NOFS);
|
||||
if (!dk)
|
||||
return ERR_PTR(-ENOMEM);
|
||||
refcount_set(&dk->dk_refcount, 1);
|
||||
dk->dk_mode = ci->ci_mode;
|
||||
dk->dk_ctfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key,
|
||||
ci->ci_inode);
|
||||
if (IS_ERR(dk->dk_ctfm)) {
|
||||
err = PTR_ERR(dk->dk_ctfm);
|
||||
dk->dk_ctfm = NULL;
|
||||
goto err_free_dk;
|
||||
}
|
||||
memcpy(dk->dk_descriptor, ci->ci_master_key_descriptor,
|
||||
FSCRYPT_KEY_DESCRIPTOR_SIZE);
|
||||
memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize);
|
||||
|
||||
return find_or_insert_direct_key(dk, raw_key, ci);
|
||||
|
||||
err_free_dk:
|
||||
free_direct_key(dk);
|
||||
return ERR_PTR(err);
|
||||
}
|
||||
|
||||
/* v1 policy, DIRECT_KEY: use the master key directly */
|
||||
static int setup_v1_file_key_direct(struct fscrypt_info *ci,
|
||||
const u8 *raw_master_key)
|
||||
{
|
||||
const struct fscrypt_mode *mode = ci->ci_mode;
|
||||
struct fscrypt_direct_key *dk;
|
||||
|
||||
if (!fscrypt_mode_supports_direct_key(mode)) {
|
||||
fscrypt_warn(ci->ci_inode,
|
||||
"Direct key mode not allowed with %s",
|
||||
mode->friendly_name);
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
if (ci->ci_data_mode != ci->ci_filename_mode) {
|
||||
fscrypt_warn(ci->ci_inode,
|
||||
"Direct key mode not allowed with different contents and filenames modes");
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
/* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
|
||||
if (WARN_ON(mode->needs_essiv))
|
||||
return -EINVAL;
|
||||
|
||||
dk = fscrypt_get_direct_key(ci, raw_master_key);
|
||||
if (IS_ERR(dk))
|
||||
return PTR_ERR(dk);
|
||||
ci->ci_direct_key = dk;
|
||||
ci->ci_ctfm = dk->dk_ctfm;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* v1 policy, !DIRECT_KEY: derive the file's encryption key */
|
||||
static int setup_v1_file_key_derived(struct fscrypt_info *ci,
|
||||
const u8 *raw_master_key)
|
||||
{
|
||||
u8 *derived_key;
|
||||
int err;
|
||||
|
||||
/*
|
||||
* This cannot be a stack buffer because it will be passed to the
|
||||
* scatterlist crypto API during derive_key_aes().
|
||||
*/
|
||||
derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS);
|
||||
if (!derived_key)
|
||||
return -ENOMEM;
|
||||
|
||||
err = derive_key_aes(raw_master_key, ci->ci_nonce,
|
||||
derived_key, ci->ci_mode->keysize);
|
||||
if (err)
|
||||
goto out;
|
||||
|
||||
err = fscrypt_set_derived_key(ci, derived_key);
|
||||
out:
|
||||
kzfree(derived_key);
|
||||
return err;
|
||||
}
|
||||
|
||||
int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, const u8 *raw_master_key)
|
||||
{
|
||||
if (ci->ci_flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
|
||||
return setup_v1_file_key_direct(ci, raw_master_key);
|
||||
else
|
||||
return setup_v1_file_key_derived(ci, raw_master_key);
|
||||
}
|
||||
|
||||
int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci)
|
||||
{
|
||||
struct key *key;
|
||||
const struct fscrypt_key *payload;
|
||||
int err;
|
||||
|
||||
key = find_and_lock_process_key(FSCRYPT_KEY_DESC_PREFIX,
|
||||
ci->ci_master_key_descriptor,
|
||||
ci->ci_mode->keysize, &payload);
|
||||
if (key == ERR_PTR(-ENOKEY) && ci->ci_inode->i_sb->s_cop->key_prefix) {
|
||||
key = find_and_lock_process_key(ci->ci_inode->i_sb->s_cop->key_prefix,
|
||||
ci->ci_master_key_descriptor,
|
||||
ci->ci_mode->keysize, &payload);
|
||||
}
|
||||
if (IS_ERR(key))
|
||||
return PTR_ERR(key);
|
||||
|
||||
err = fscrypt_setup_v1_file_key(ci, payload->raw);
|
||||
up_read(&key->sem);
|
||||
key_put(key);
|
||||
return err;
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user