linux/fs/crypto
Eric Biggers 777afe4e68 fscrypt: use smp_load_acquire() for ->s_master_keys
Normally smp_store_release() or cmpxchg_release() is paired with
smp_load_acquire().  Sometimes smp_load_acquire() can be replaced with
the more lightweight READ_ONCE().  However, for this to be safe, all the
published memory must only be accessed in a way that involves the
pointer itself.  This may not be the case if allocating the object also
involves initializing a static or global variable, for example.

super_block::s_master_keys is a keyring, which is internal to and is
allocated by the keyrings subsystem.  By using READ_ONCE() for it, we're
relying on internal implementation details of the keyrings subsystem.

Remove this fragile assumption by using smp_load_acquire() instead.

(Note: I haven't seen any real-world problems here.  This change is just
fixing the code to be guaranteed correct and less fragile.)

Fixes: 22d94f493b ("fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl")
Link: https://lore.kernel.org/r/20200721225920.114347-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-07-21 16:02:13 -07:00
..
bio.c fscrypt: add inline encryption support 2020-07-08 10:29:30 -07:00
crypto.c fscrypt: rename FS_KEY_DERIVATION_NONCE_SIZE 2020-07-20 17:26:33 -07:00
fname.c fscrypt: switch fscrypt_do_sha256() to use the SHA-256 library 2020-07-21 16:02:13 -07:00
fscrypt_private.h fscrypt: use smp_load_acquire() for fscrypt_prepared_key 2020-07-21 16:02:13 -07:00
hkdf.c fscrypt: use crypto_shash_tfm_digest() 2020-05-08 15:32:14 +10:00
hooks.c fscrypt: fix all kerneldoc warnings 2020-05-12 16:37:17 -07:00
inline_crypt.c fscrypt: use smp_load_acquire() for fscrypt_prepared_key 2020-07-21 16:02:13 -07:00
Kconfig fscrypt: switch fscrypt_do_sha256() to use the SHA-256 library 2020-07-21 16:02:13 -07:00
keyring.c fscrypt: use smp_load_acquire() for ->s_master_keys 2020-07-21 16:02:13 -07:00
keysetup_v1.c fscrypt: rename FS_KEY_DERIVATION_NONCE_SIZE 2020-07-20 17:26:33 -07:00
keysetup.c fscrypt: use smp_load_acquire() for fscrypt_prepared_key 2020-07-21 16:02:13 -07:00
Makefile fscrypt: add inline encryption support 2020-07-08 10:29:30 -07:00
policy.c fscrypt: restrict IV_INO_LBLK_* to AES-256-XTS 2020-07-21 11:12:57 -07:00