The current locking approach of the DRBG tries to keep the protected
code paths very minimal. It is therefore possible that two threads query
one DRBG instance at the same time. When thread A requests random
numbers, a shadow copy of the DRBG state is created upon which the
request for A is processed. After finishing the state for A's request is
merged back into the DRBG state. If now thread B requests random numbers
from the same DRBG after the request for thread A is received, but
before A's shadow state is merged back, the random numbers for B will be
identical to the ones for A. Please note that the time window is very
small for this scenario.
To prevent that there is even a theoretical chance for thread A and B
having the same DRBG state, the current time stamp is provided as
additional information string for each new request.
The addition of the time stamp as additional information string implies
that now all generate functions must be capable to process a linked
list with additional information strings instead of a scalar.
CC: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The DRBG-style linked list to manage input data that is fed into the
cipher invocations is replaced with the kernel linked list
implementation.
The change is transparent to users of the interfaces offered by the
DRBG. Therefore, no changes to the testmgr code is needed.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The header file includes the definition of:
* DRBG data structures with
- struct drbg_state as main structure
- struct drbg_core referencing the backend ciphers
- struct drbg_state_ops callbach handlers for specific code
supporting the Hash, HMAC, CTR DRBG implementations
- struct drbg_conc defining a linked list for input data
- struct drbg_test_data holding the test "entropy" data for CAVS
testing and testmgr.c
- struct drbg_gen allowing test data, additional information
string and personalization string data to be funneled through
the kernel crypto API -- the DRBG requires additional
parameters when invoking the reset and random number
generation requests than intended by the kernel crypto API
* wrapper function to the kernel crypto API functions using struct
drbg_gen to pass through all data needed for DRBG
* wrapper functions to kernel crypto API functions usable for testing
code to inject test_data into the DRBG as needed by CAVS testing and
testmgr.c.
* DRBG flags required for the operation of the DRBG and for selecting
the particular DRBG type and backend cipher
* getter functions for data from struct drbg_core
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Stephan Mueller