Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux
Pull fscrypt updates from Eric Biggers:
"Fix flakiness in a test by releasing the quota synchronously when a
key is removed, and other minor cleanups"
* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux:
fscrypt: shrink the size of struct fscrypt_inode_info slightly
fscrypt: write CBC-CTS instead of CTS-CBC
fscrypt: clear keyring before calling key_put()
fscrypt: explicitly require that inode->i_blkbits be set
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index e86b886..04eaab0 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -338,11 +338,14 @@
Currently, the following pairs of encryption modes are supported:
-- AES-256-XTS for contents and AES-256-CTS-CBC for filenames
+- AES-256-XTS for contents and AES-256-CBC-CTS for filenames
- AES-256-XTS for contents and AES-256-HCTR2 for filenames
- Adiantum for both contents and filenames
-- AES-128-CBC-ESSIV for contents and AES-128-CTS-CBC for filenames
-- SM4-XTS for contents and SM4-CTS-CBC for filenames
+- AES-128-CBC-ESSIV for contents and AES-128-CBC-CTS for filenames
+- SM4-XTS for contents and SM4-CBC-CTS for filenames
+
+Note: in the API, "CBC" means CBC-ESSIV, and "CTS" means CBC-CTS.
+So, for example, FSCRYPT_MODE_AES_256_CTS means AES-256-CBC-CTS.
Authenticated encryption modes are not currently supported because of
the difficulty of dealing with ciphertext expansion. Therefore,
@@ -351,11 +354,11 @@
`CBC-ESSIV mode
<https://en.wikipedia.org/wiki/Disk_encryption_theory#Encrypted_salt-sector_initialization_vector_(ESSIV)>`_,
or a wide-block cipher. Filenames encryption uses a
-block cipher in `CTS-CBC mode
+block cipher in `CBC-CTS mode
<https://en.wikipedia.org/wiki/Ciphertext_stealing>`_ or a wide-block
cipher.
-The (AES-256-XTS, AES-256-CTS-CBC) pair is the recommended default.
+The (AES-256-XTS, AES-256-CBC-CTS) pair is the recommended default.
It is also the only option that is *guaranteed* to always be supported
if the kernel supports fscrypt at all; see `Kernel config options`_.
@@ -364,7 +367,7 @@
*wide-block cipher*, also called a tweakable super-pseudorandom
permutation, has the property that changing one bit scrambles the
entire result.) As described in `Filenames encryption`_, a wide-block
-cipher is the ideal mode for the problem domain, though CTS-CBC is the
+cipher is the ideal mode for the problem domain, though CBC-CTS is the
"least bad" choice among the alternatives. For more information about
HCTR2, see `the HCTR2 paper <https://eprint.iacr.org/2021/1441.pdf>`_.
@@ -375,13 +378,13 @@
acceleration is unavailable. For more information about Adiantum, see
`the Adiantum paper <https://eprint.iacr.org/2018/720.pdf>`_.
-The (AES-128-CBC-ESSIV, AES-128-CTS-CBC) pair exists only to support
+The (AES-128-CBC-ESSIV, AES-128-CBC-CTS) pair exists only to support
systems whose only form of AES acceleration is an off-CPU crypto
accelerator such as CAAM or CESA that does not support XTS.
The remaining mode pairs are the "national pride ciphers":
-- (SM4-XTS, SM4-CTS-CBC)
+- (SM4-XTS, SM4-CBC-CTS)
Generally speaking, these ciphers aren't "bad" per se, but they
receive limited security review compared to the usual choices such as
@@ -393,7 +396,7 @@
Enabling fscrypt support (CONFIG_FS_ENCRYPTION) automatically pulls in
only the basic support from the crypto API needed to use AES-256-XTS
-and AES-256-CTS-CBC encryption. For optimal performance, it is
+and AES-256-CBC-CTS encryption. For optimal performance, it is
strongly recommended to also enable any available platform-specific
kconfig options that provide acceleration for the algorithm(s) you
wish to use. Support for any "non-default" encryption modes typically
@@ -407,7 +410,7 @@
the file contents mode doesn't need to supported in the kernel crypto
API, but the filenames mode still does.
-- AES-256-XTS and AES-256-CTS-CBC
+- AES-256-XTS and AES-256-CBC-CTS
- Recommended:
- arm64: CONFIG_CRYPTO_AES_ARM64_CE_BLK
- x86: CONFIG_CRYPTO_AES_NI_INTEL
@@ -433,7 +436,7 @@
- x86: CONFIG_CRYPTO_NHPOLY1305_SSE2
- x86: CONFIG_CRYPTO_NHPOLY1305_AVX2
-- AES-128-CBC-ESSIV and AES-128-CTS-CBC:
+- AES-128-CBC-ESSIV and AES-128-CBC-CTS:
- Mandatory:
- CONFIG_CRYPTO_ESSIV
- CONFIG_CRYPTO_SHA256 or another SHA-256 implementation
@@ -521,7 +524,7 @@
inode number (for `IV_INO_LBLK_64 policies`_) included in the IVs.
Thus, IV reuse is limited to within a single directory.
-With CTS-CBC, the IV reuse means that when the plaintext filenames share a
+With CBC-CTS, the IV reuse means that when the plaintext filenames share a
common prefix at least as long as the cipher block size (16 bytes for AES), the
corresponding encrypted filenames will also share a common prefix. This is
undesirable. Adiantum and HCTR2 do not have this weakness, as they are
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 1892356..8371e4e 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -222,16 +222,19 @@ struct fscrypt_inode_info {
struct fscrypt_prepared_key ci_enc_key;
/* True if ci_enc_key should be freed when this struct is freed */
- bool ci_owns_key;
+ u8 ci_owns_key : 1;
#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
/*
* True if this inode will use inline encryption (blk-crypto) instead of
* the traditional filesystem-layer encryption.
*/
- bool ci_inlinecrypt;
+ u8 ci_inlinecrypt : 1;
#endif
+ /* True if ci_dirhash_key is initialized */
+ u8 ci_dirhash_key_initialized : 1;
+
/*
* log2 of the data unit size (granularity of contents encryption) of
* this file. This is computable from ci_policy and ci_inode but is
@@ -242,6 +245,9 @@ struct fscrypt_inode_info {
/* Cached value: log2 of number of data units per FS block */
u8 ci_data_units_per_block_bits;
+ /* Hashed inode number. Only set for IV_INO_LBLK_32 */
+ u32 ci_hashed_ino;
+
/*
* Encryption mode used for this inode. It corresponds to either the
* contents or filenames encryption mode, depending on the inode type.
@@ -276,16 +282,12 @@ struct fscrypt_inode_info {
* the plaintext filenames -- currently just casefolded directories.
*/
siphash_key_t ci_dirhash_key;
- bool ci_dirhash_key_initialized;
/* The encryption policy used by this inode */
union fscrypt_policy ci_policy;
/* This inode's nonce, copied from the fscrypt_context */
u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
-
- /* Hashed inode number. Only set for IV_INO_LBLK_32 */
- u32 ci_hashed_ino;
};
typedef enum {
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 0edf0b5..6681a71 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -74,8 +74,12 @@ void fscrypt_put_master_key(struct fscrypt_master_key *mk)
* that concurrent keyring lookups can no longer find it.
*/
WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 0);
- key_put(mk->mk_users);
- mk->mk_users = NULL;
+ if (mk->mk_users) {
+ /* Clear the keyring so the quota gets released right away. */
+ keyring_clear(mk->mk_users);
+ key_put(mk->mk_users);
+ mk->mk_users = NULL;
+ }
call_rcu(&mk->mk_rcu_head, fscrypt_free_master_key);
}
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index d71f7c7..b4fe01e 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -23,7 +23,7 @@ struct fscrypt_mode fscrypt_modes[] = {
.blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_256_XTS,
},
[FSCRYPT_MODE_AES_256_CTS] = {
- .friendly_name = "AES-256-CTS-CBC",
+ .friendly_name = "AES-256-CBC-CTS",
.cipher_str = "cts(cbc(aes))",
.keysize = 32,
.security_strength = 32,
@@ -38,7 +38,7 @@ struct fscrypt_mode fscrypt_modes[] = {
.blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV,
},
[FSCRYPT_MODE_AES_128_CTS] = {
- .friendly_name = "AES-128-CTS-CBC",
+ .friendly_name = "AES-128-CBC-CTS",
.cipher_str = "cts(cbc(aes))",
.keysize = 16,
.security_strength = 16,
@@ -53,7 +53,7 @@ struct fscrypt_mode fscrypt_modes[] = {
.blk_crypto_mode = BLK_ENCRYPTION_MODE_SM4_XTS,
},
[FSCRYPT_MODE_SM4_CTS] = {
- .friendly_name = "SM4-CTS-CBC",
+ .friendly_name = "SM4-CBC-CTS",
.cipher_str = "cts(cbc(sm4))",
.keysize = 16,
.security_strength = 16,
@@ -687,7 +687,7 @@ int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported)
/**
* fscrypt_prepare_new_inode() - prepare to create a new inode in a directory
* @dir: a possibly-encrypted directory
- * @inode: the new inode. ->i_mode must be set already.
+ * @inode: the new inode. ->i_mode and ->i_blkbits must be set already.
* ->i_ino doesn't need to be set yet.
* @encrypt_ret: (output) set to %true if the new inode will be encrypted
*
@@ -717,6 +717,9 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
if (IS_ERR(policy))
return PTR_ERR(policy);
+ if (WARN_ON_ONCE(inode->i_blkbits == 0))
+ return -EINVAL;
+
if (WARN_ON_ONCE(inode->i_mode == 0))
return -EINVAL;
