Commit graph

13 commits

Author SHA1 Message Date
Stephan Mueller
ce5481d01f crypto: drbg - fix failure of generating multiple of 2**16 bytes
The function drbg_generate_long slices the request into 2**16 byte
or smaller chunks. However, the loop, however invokes the random number
generation function with zero bytes when the request size is a multiple
of 2**16 bytes. The fix prevents zero bytes requests.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-08-01 22:36:14 +08:00
Fengguang Wu
96956aef2f crypto: drbg - drbg_exit() can be static
CC: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-10 16:52:04 +08:00
Stephan Mueller
5b635e280e crypto: drbg - HMAC-SHA1 DRBG has crypto strength of 128 bits
The patch corrects the security strength of the HMAC-SHA1 DRBG to 128
bits. This strength defines the size of the seed required for the DRBG.
Thus, the patch lowers the seeding requirement from 256 bits to 128 bits
for HMAC-SHA1.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-08 21:18:25 +08:00
Stephan Mueller
27e4de2bd1 crypto: drbg - Mix a time stamp into DRBG state
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>
2014-07-08 21:18:25 +08:00
Stephan Mueller
4f15071879 crypto: drbg - Select correct DRBG core for stdrng
When the DRBG is initialized, the core is looked up using the DRBG name.
The name that can be used for the lookup is registered in
cra_driver_name. The cra_name value contains stdrng.

Thus, the lookup code must use crypto_tfm_alg_driver_name to obtain the
precise DRBG name and select the correct DRBG.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-08 21:18:24 +08:00
Stephan Mueller
72e7c25aa6 crypto: drbg - Call CTR DRBG DF function only once
The CTR DRBG requires the update function to be called twice when
generating a random number. In both cases, update function must process
the additional information string by using the DF function. As the DF
produces the same result in both cases, we can save one invocation of
the DF function when the first DF function result is reused.

The result of the DF function is stored in the scratchpad storage. The
patch ensures that the scratchpad is not cleared when we want to reuse
the DF result. For achieving this, the CTR DRBG update function must
know by whom and in which scenario it is called. This information is
provided with the reseed parameter to the update function.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-08 21:18:24 +08:00
Stephan Mueller
a9089571f2 crypto: drbg - Fix format string for debugging statements
The initial format strings caused warnings on several architectures. The
updated format strings now match the variable types.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
CC: Joe Perches <joe@perches.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-08 21:18:23 +08:00
Stephan Mueller
e25e47ec3d crypto: drbg - cleanup of preprocessor macros
The structure used to construct the module description line was marked
problematic by the sparse code analysis tool. The module line
description now does not contain any ifdefs to prevent error reports
from sparse.

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>
2014-07-08 21:18:23 +08:00
Herbert Xu
f2c89a10de crypto: drbg - Use Kconfig to ensure at least one RNG option is set
This patch removes the build-time test that ensures at least one RNG
is set.  Instead we will simply not build drbg if no options are set
through Kconfig.

This also fixes a typo in the name of the Kconfig option CRYTPO_DRBG
(should be CRYPTO_DRBG).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-04 22:15:08 +08:00
Stephan Mueller
8c98716601 crypto: drbg - use of kernel linked list
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>
2014-07-04 21:09:20 +08:00
Stephan Mueller
8fecaad77f crypto: drbg - fix memory corruption for AES192
For the CTR DRBG, the drbg_state->scratchpad temp buffer (i.e. the
memory location immediately before the drbg_state->tfm variable
is the buffer that the BCC function operates on. BCC operates
blockwise. Making the temp buffer drbg_statelen(drbg) in size is
sufficient when the DRBG state length is a multiple of the block
size. For AES192 this is not the case and the length for temp is
insufficient (yes, that also means for such ciphers, the final
output of all BCC rounds are truncated before used to update the
state of the DRBG!!).

The patch enlarges the temp buffer from drbg_statelen to
drbg_statelen + drbg_blocklen to have sufficient space.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-07-04 11:04:53 +08:00
Stephan Mueller
c0eedf8034 crypto: drbg - simplify ordering of linked list in drbg_ctr_df
As reported by a static code analyzer, the code for the ordering of
the linked list can be simplified.

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>
2014-06-26 14:46:31 +08:00
Stephan Mueller
541af946fe crypto: drbg - SP800-90A Deterministic Random Bit Generator
This is a clean-room implementation of the DRBG defined in SP800-90A.
All three viable DRBGs defined in the standard are implemented:

 * HMAC: This is the leanest DRBG and compiled per default
 * Hash: The more complex DRBG can be enabled at compile time
 * CTR: The most complex DRBG can also be enabled at compile time

The DRBG implementation offers the following:

 * All three DRBG types are implemented with a derivation function.
 * All DRBG types are available with and without prediction resistance.
 * All SHA types of SHA-1, SHA-256, SHA-384, SHA-512 are available for
   the HMAC and Hash DRBGs.
 * All AES types of AES-128, AES-192 and AES-256 are available for the
   CTR DRBG.
 * A self test is implemented with drbg_healthcheck().
 * The FIPS 140-2 continuous self test is implemented.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-06-20 21:26:08 +08:00