* Heavily modified since then.
*/
-#include <keys/user-type.h>
-#include <linux/hashtable.h>
-#include <linux/scatterlist.h>
#include <crypto/aes.h>
-#include <crypto/algapi.h>
#include <crypto/sha.h>
#include <crypto/skcipher.h>
+#include <linux/key.h>
+
#include "fscrypt_private.h"
static struct crypto_shash *essiv_hash_tfm;
-/* 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);
-}
-
static struct fscrypt_mode available_modes[] = {
[FSCRYPT_MODE_AES_256_XTS] = {
.friendly_name = "AES-256-XTS",
}
/* Create a symmetric cipher object for the given encryption mode and key */
-static struct crypto_skcipher *
-fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
- const struct inode *inode)
+struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode,
+ const u8 *raw_key,
+ const struct inode *inode)
{
struct crypto_skcipher *tfm;
int err;
return ERR_PTR(err);
}
-/* 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);
- }
-}
-
-static void 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);
-}
-
static int derive_essiv_salt(const u8 *key, int keysize, u8 *salt)
{
struct crypto_shash *tfm = READ_ONCE(essiv_hash_tfm);
}
/* Given the per-file key, set up the file's crypto transform object(s) */
-static int fscrypt_set_derived_key(struct fscrypt_info *ci,
- const u8 *derived_key)
+int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key)
{
struct fscrypt_mode *mode = ci->ci_mode;
struct crypto_skcipher *ctfm;
return 0;
}
-/* 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;
-}
-
-static 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);
-}
-
-static 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;
-}
-
/*
* Find the master key, then set up the inode's actual encryption key.
*/
return;
if (ci->ci_direct_key) {
- put_direct_key(ci->ci_direct_key);
+ fscrypt_put_direct_key(ci->ci_direct_key);
} else {
crypto_free_skcipher(ci->ci_ctfm);
crypto_free_cipher(ci->ci_essiv_tfm);
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