From: Eric Biggers <ebiggers@xxxxxxxxxx>
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.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/crypto/Makefile | 8 +-
fs/crypto/fscrypt_private.h | 17 ++
fs/crypto/keyinfo.c | 328 +---------------------------------
fs/crypto/keysetup_v1.c | 338 ++++++++++++++++++++++++++++++++++++
4 files changed, 369 insertions(+), 322 deletions(-)
create mode 100644 fs/crypto/keysetup_v1.c
diff --git a/fs/crypto/Makefile b/fs/crypto/Makefile
index 4f0df5e682e49f..1fba255c34ca56 100644
--- a/fs/crypto/Makefile
+++ b/fs/crypto/Makefile
@@ -1,5 +1,11 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_FS_ENCRYPTION) += fscrypto.o
-fscrypto-y := crypto.o fname.o hooks.o keyinfo.o policy.o
+fscrypto-y := crypto.o \
+ fname.o \
+ hooks.o \
+ keyinfo.o \
+ keysetup_v1.o \
+ policy.o
+
fscrypto-$(CONFIG_BLOCK) += bio.o
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 56bac5c7ef408a..387b44b255f6ab 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -173,4 +173,21 @@ fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
}
+extern struct crypto_skcipher *
+fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
+ const struct inode *inode);
+
+extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
+ const u8 *derived_key);
+
+/* keysetup_v1.c */
+
+extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
+
+extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
+ const u8 *raw_master_key);
+
+extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
+ struct fscrypt_info *ci);
+
#endif /* _FSCRYPT_PRIVATE_H */
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index c6bf44d6411189..f4a47448e9efa1 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -8,130 +8,15 @@
* 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",
@@ -188,9 +73,9 @@ select_encryption_mode(const struct fscrypt_info *ci, const struct inode *inode)
}
/* 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;
@@ -232,113 +117,6 @@ fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
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);
@@ -409,8 +187,7 @@ static int init_essiv_generator(struct fscrypt_info *ci, const u8 *raw_key,
}
/* 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;
@@ -434,97 +211,6 @@ static int fscrypt_set_derived_key(struct fscrypt_info *ci,
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.
*/
@@ -539,7 +225,7 @@ static void put_crypt_info(struct fscrypt_info *ci)
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);
diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c
new file mode 100644
index 00000000000000..631690bb6ed54c
--- /dev/null
+++ b/fs/crypto/keysetup_v1.c
@@ -0,0 +1,338 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Key setup for v1 encryption policies
+ *
+ * Copyright 2015, 2019 Google LLC
+ */
+
+/*
+ * This file implements compatibility functions for the original encryption
+ * policy version ("v1"), including:
+ *
+ * - Deriving per-file keys using the AES-128-ECB based KDF
+ * (rather than the new method of using HKDF-SHA512)
+ *
+ * - Retrieving fscrypt master keys from process-subscribed keyrings
+ * (rather than the new method of using a filesystem-level keyring)
+ *
+ * - Handling policies with the DIRECT_KEY flag set using a master key table
+ * (rather than the new method of implementing DIRECT_KEY with per-mode keys
+ * managed alongside the master keys in the filesystem-level keyring)
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/skcipher.h>
+#include <keys/user-type.h>
+#include <linux/hashtable.h>
+#include <linux/scatterlist.h>
+
+#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;
+}
--
2.22.0.770.g0f2c4a37fd-goog
