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fscrypt updates for 6.9
Fix flakiness in a test by releasing the quota synchronously when a key is removed, and other minor cleanups. -----BEGIN PGP SIGNATURE----- iIoEABYIADIWIQSacvsUNc7UX4ntmEPzXCl4vpKOKwUCZe/STxQcZWJpZ2dlcnNA Z29vZ2xlLmNvbQAKCRDzXCl4vpKOKyVAAQCJQr5l3fU+rm1FVpuVg8q/pbPdi5wJ N31pYFvY3AehtQEArdPNtBbXW3V7i9OL6CDmesuNtGr3Il5KRV1h89yyYgY= =RGab -----END PGP SIGNATURE----- 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
This commit is contained in:
Linus Torvalds
commit
3bf95d567d
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@ -338,11 +338,14 @@ Supported modes
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Currently, the following pairs of encryption modes are supported:
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- AES-256-XTS for contents and AES-256-CTS-CBC for filenames
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- AES-256-XTS for contents and AES-256-CBC-CTS for filenames
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- AES-256-XTS for contents and AES-256-HCTR2 for filenames
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- Adiantum for both contents and filenames
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- AES-128-CBC-ESSIV for contents and AES-128-CTS-CBC for filenames
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- SM4-XTS for contents and SM4-CTS-CBC for filenames
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- AES-128-CBC-ESSIV for contents and AES-128-CBC-CTS for filenames
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- SM4-XTS for contents and SM4-CBC-CTS for filenames
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Note: in the API, "CBC" means CBC-ESSIV, and "CTS" means CBC-CTS.
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So, for example, FSCRYPT_MODE_AES_256_CTS means AES-256-CBC-CTS.
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Authenticated encryption modes are not currently supported because of
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the difficulty of dealing with ciphertext expansion. Therefore,
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@ -351,11 +354,11 @@ contents encryption uses a block cipher in `XTS mode
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`CBC-ESSIV mode
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<https://en.wikipedia.org/wiki/Disk_encryption_theory#Encrypted_salt-sector_initialization_vector_(ESSIV)>`_,
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or a wide-block cipher. Filenames encryption uses a
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block cipher in `CTS-CBC mode
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block cipher in `CBC-CTS mode
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<https://en.wikipedia.org/wiki/Ciphertext_stealing>`_ or a wide-block
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cipher.
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The (AES-256-XTS, AES-256-CTS-CBC) pair is the recommended default.
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The (AES-256-XTS, AES-256-CBC-CTS) pair is the recommended default.
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It is also the only option that is *guaranteed* to always be supported
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if the kernel supports fscrypt at all; see `Kernel config options`_.
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@ -364,7 +367,7 @@ upgrades the filenames encryption to use a wide-block cipher. (A
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*wide-block cipher*, also called a tweakable super-pseudorandom
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permutation, has the property that changing one bit scrambles the
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entire result.) As described in `Filenames encryption`_, a wide-block
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cipher is the ideal mode for the problem domain, though CTS-CBC is the
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cipher is the ideal mode for the problem domain, though CBC-CTS is the
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"least bad" choice among the alternatives. For more information about
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HCTR2, see `the HCTR2 paper <https://eprint.iacr.org/2021/1441.pdf>`_.
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@ -375,13 +378,13 @@ the work is done by XChaCha12, which is much faster than AES when AES
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acceleration is unavailable. For more information about Adiantum, see
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`the Adiantum paper <https://eprint.iacr.org/2018/720.pdf>`_.
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The (AES-128-CBC-ESSIV, AES-128-CTS-CBC) pair exists only to support
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The (AES-128-CBC-ESSIV, AES-128-CBC-CTS) pair exists only to support
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systems whose only form of AES acceleration is an off-CPU crypto
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accelerator such as CAAM or CESA that does not support XTS.
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The remaining mode pairs are the "national pride ciphers":
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- (SM4-XTS, SM4-CTS-CBC)
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- (SM4-XTS, SM4-CBC-CTS)
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Generally speaking, these ciphers aren't "bad" per se, but they
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receive limited security review compared to the usual choices such as
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@ -393,7 +396,7 @@ Kernel config options
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Enabling fscrypt support (CONFIG_FS_ENCRYPTION) automatically pulls in
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only the basic support from the crypto API needed to use AES-256-XTS
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and AES-256-CTS-CBC encryption. For optimal performance, it is
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and AES-256-CBC-CTS encryption. For optimal performance, it is
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strongly recommended to also enable any available platform-specific
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kconfig options that provide acceleration for the algorithm(s) you
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wish to use. Support for any "non-default" encryption modes typically
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@ -407,7 +410,7 @@ kernel crypto API (see `Inline encryption support`_); in that case,
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the file contents mode doesn't need to supported in the kernel crypto
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API, but the filenames mode still does.
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- AES-256-XTS and AES-256-CTS-CBC
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- AES-256-XTS and AES-256-CBC-CTS
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- Recommended:
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- arm64: CONFIG_CRYPTO_AES_ARM64_CE_BLK
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- x86: CONFIG_CRYPTO_AES_NI_INTEL
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@ -433,7 +436,7 @@ API, but the filenames mode still does.
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- x86: CONFIG_CRYPTO_NHPOLY1305_SSE2
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- x86: CONFIG_CRYPTO_NHPOLY1305_AVX2
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- AES-128-CBC-ESSIV and AES-128-CTS-CBC:
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- AES-128-CBC-ESSIV and AES-128-CBC-CTS:
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- Mandatory:
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- CONFIG_CRYPTO_ESSIV
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- CONFIG_CRYPTO_SHA256 or another SHA-256 implementation
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@ -521,7 +524,7 @@ alternatively has the file's nonce (for `DIRECT_KEY policies`_) or
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inode number (for `IV_INO_LBLK_64 policies`_) included in the IVs.
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Thus, IV reuse is limited to within a single directory.
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With CTS-CBC, the IV reuse means that when the plaintext filenames share a
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With CBC-CTS, the IV reuse means that when the plaintext filenames share a
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common prefix at least as long as the cipher block size (16 bytes for AES), the
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corresponding encrypted filenames will also share a common prefix. This is
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undesirable. Adiantum and HCTR2 do not have this weakness, as they are
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@ -222,16 +222,19 @@ struct fscrypt_inode_info {
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struct fscrypt_prepared_key ci_enc_key;
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/* True if ci_enc_key should be freed when this struct is freed */
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bool ci_owns_key;
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u8 ci_owns_key : 1;
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#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
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/*
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* True if this inode will use inline encryption (blk-crypto) instead of
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* the traditional filesystem-layer encryption.
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*/
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bool ci_inlinecrypt;
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u8 ci_inlinecrypt : 1;
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#endif
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/* True if ci_dirhash_key is initialized */
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u8 ci_dirhash_key_initialized : 1;
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/*
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* log2 of the data unit size (granularity of contents encryption) of
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* this file. This is computable from ci_policy and ci_inode but is
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@ -242,6 +245,9 @@ struct fscrypt_inode_info {
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/* Cached value: log2 of number of data units per FS block */
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u8 ci_data_units_per_block_bits;
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/* Hashed inode number. Only set for IV_INO_LBLK_32 */
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u32 ci_hashed_ino;
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/*
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* Encryption mode used for this inode. It corresponds to either the
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* contents or filenames encryption mode, depending on the inode type.
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@ -276,16 +282,12 @@ struct fscrypt_inode_info {
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* the plaintext filenames -- currently just casefolded directories.
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*/
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siphash_key_t ci_dirhash_key;
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bool ci_dirhash_key_initialized;
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/* The encryption policy used by this inode */
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union fscrypt_policy ci_policy;
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/* This inode's nonce, copied from the fscrypt_context */
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u8 ci_nonce[FSCRYPT_FILE_NONCE_SIZE];
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/* Hashed inode number. Only set for IV_INO_LBLK_32 */
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u32 ci_hashed_ino;
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};
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typedef enum {
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@ -74,8 +74,12 @@ void fscrypt_put_master_key(struct fscrypt_master_key *mk)
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* that concurrent keyring lookups can no longer find it.
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*/
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WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 0);
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key_put(mk->mk_users);
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mk->mk_users = NULL;
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if (mk->mk_users) {
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/* Clear the keyring so the quota gets released right away. */
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keyring_clear(mk->mk_users);
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key_put(mk->mk_users);
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mk->mk_users = NULL;
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}
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call_rcu(&mk->mk_rcu_head, fscrypt_free_master_key);
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}
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@ -23,7 +23,7 @@ struct fscrypt_mode fscrypt_modes[] = {
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.blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_256_XTS,
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},
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[FSCRYPT_MODE_AES_256_CTS] = {
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.friendly_name = "AES-256-CTS-CBC",
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.friendly_name = "AES-256-CBC-CTS",
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.cipher_str = "cts(cbc(aes))",
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.keysize = 32,
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.security_strength = 32,
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@ -38,7 +38,7 @@ struct fscrypt_mode fscrypt_modes[] = {
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.blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV,
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},
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[FSCRYPT_MODE_AES_128_CTS] = {
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.friendly_name = "AES-128-CTS-CBC",
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.friendly_name = "AES-128-CBC-CTS",
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.cipher_str = "cts(cbc(aes))",
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.keysize = 16,
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.security_strength = 16,
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@ -53,7 +53,7 @@ struct fscrypt_mode fscrypt_modes[] = {
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.blk_crypto_mode = BLK_ENCRYPTION_MODE_SM4_XTS,
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},
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[FSCRYPT_MODE_SM4_CTS] = {
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.friendly_name = "SM4-CTS-CBC",
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.friendly_name = "SM4-CBC-CTS",
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.cipher_str = "cts(cbc(sm4))",
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.keysize = 16,
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.security_strength = 16,
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@ -687,7 +687,7 @@ int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported)
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/**
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* fscrypt_prepare_new_inode() - prepare to create a new inode in a directory
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* @dir: a possibly-encrypted directory
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* @inode: the new inode. ->i_mode must be set already.
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* @inode: the new inode. ->i_mode and ->i_blkbits must be set already.
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* ->i_ino doesn't need to be set yet.
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* @encrypt_ret: (output) set to %true if the new inode will be encrypted
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*
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@ -717,6 +717,9 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
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if (IS_ERR(policy))
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return PTR_ERR(policy);
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if (WARN_ON_ONCE(inode->i_blkbits == 0))
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return -EINVAL;
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if (WARN_ON_ONCE(inode->i_mode == 0))
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return -EINVAL;
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