linux

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David Howells 63c8e45255 KEYS: Fix race between updating and finding a negative key commit `363b02dab0` upstream. Consolidate KEY_FLAG_INSTANTIATED, KEY_FLAG_NEGATIVE and the rejection error into one field such that: (1) The instantiation state can be modified/read atomically. (2) The error can be accessed atomically with the state. (3) The error isn't stored unioned with the payload pointers. This deals with the problem that the state is spread over three different objects (two bits and a separate variable) and reading or updating them atomically isn't practical, given that not only can uninstantiated keys change into instantiated or rejected keys, but rejected keys can also turn into instantiated keys - and someone accessing the key might not be using any locking. The main side effect of this problem is that what was held in the payload may change, depending on the state. For instance, you might observe the key to be in the rejected state. You then read the cached error, but if the key semaphore wasn't locked, the key might've become instantiated between the two reads - and you might now have something in hand that isn't actually an error code. The state is now KEY_IS_UNINSTANTIATED, KEY_IS_POSITIVE or a negative error code if the key is negatively instantiated. The key_is_instantiated() function is replaced with key_is_positive() to avoid confusion as negative keys are also 'instantiated'. Additionally, barriering is included: (1) Order payload-set before state-set during instantiation. (2) Order state-read before payload-read when using the key. Further separate barriering is necessary if RCU is being used to access the payload content after reading the payload pointers. Fixes: `146aa8b145` ("KEYS: Merge the type-specific data with the payload data") Reported-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		6 years ago
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encrypted-keys	KEYS: Fix race between updating and finding a negative key	6 years ago
Kconfig	security/keys: rewrite all of big_key crypto	6 years ago
Makefile	KEYS: Add KEYCTL_DH_COMPUTE command	7 years ago
big_key.c	KEYS: Fix race between updating and finding a negative key	6 years ago
compat.c	KEYS: Add placeholder for KDF usage with DH	7 years ago
dh.c	KEYS: Add placeholder for KDF usage with DH	7 years ago
gc.c	KEYS: Fix race between updating and finding a negative key	6 years ago
internal.h	KEYS: prevent creating a different user's keyrings	6 years ago
key.c	KEYS: Fix race between updating and finding a negative key	6 years ago
keyctl.c	KEYS: Fix race between updating and finding a negative key	6 years ago
keyring.c	KEYS: Fix race between updating and finding a negative key	6 years ago
permission.c	KEYS: Move the flags representing required permission to linux/key.h	9 years ago
persistent.c	KEYS: Strip trailing spaces	7 years ago
proc.c	KEYS: Fix race between updating and finding a negative key	6 years ago
process_keys.c	KEYS: Fix race between updating and finding a negative key	6 years ago
request_key.c	KEYS: Fix race between updating and finding a negative key	6 years ago
request_key_auth.c	KEYS: Fix race between updating and finding a negative key	6 years ago
sysctl.c	security: Convert use of typedef ctl_table to struct ctl_table	9 years ago
trusted.c	KEYS: Fix race between updating and finding a negative key	6 years ago
trusted.h	keys, trusted: move struct trusted_key_options to trusted-type.h	8 years ago
user_defined.c	KEYS: Fix race between updating and finding a negative key	6 years ago