Hi, as of now, the DRBG is only seeded from get_random_bytes. In various circumstances, the nonblocking_pool behind get_random_bytes may not be fully seeded from hardware events at the time the DRBG requires to be seeded. Based on the discussion in [1], the DRBG seeding is updated such that it does not completely rely on get_random_bytes any more. The seeding approach can be characterized as follows: 1. pull buffer of size entropy + nonce from get_random_bytes 2. pull another buffer of size entropy + nonce from my Jitter RNG 3. concatenate both buffers 4. seed the DRBG with the concatenated buffer 5. trigger the async invocation of the blocking API for accessing the nonblocking pool with a buffer of size entropy 6. return the DRBG instance to the caller without waiting for the completion of step 5 7. at some point in time, the blocking API returns with a full buffer which is then used to re-seed the DRBG This way, we will get entropy during the first initialization without blocking. The patch set adds a blocking API to access the nonblocking pool to wait until the nonblocking pool is initialized. Note: the DRBG and Jitter RNG patches are against the current cryptodev-2.6 tree. The new Jitter RNG is an RNG that has large set of tests and was presented on LKML some time back. After speaking with mathematicians at NIST, that Jitter RNG approach would be acceptable from their side as a noise source. Note, I personally think that the Jitter RNG has sufficient entropy in almost all circumstances (see the massive testing I conducted on all more widely used CPUs as shown in [2]). Changes v9: * patch 01: initialize return code Changes v8: * patch 01: make get_blocking_random_bytes to return the wait_event_interruptible error code * patch 03: catch the ERESTARTSYS error code from get_blocking_random_bytes Changes v7: * patch 01: Catch ERESTARTSYS error for wait_event_interruptible * patch 03: move the cancel invocation to drbg_uninstantiate to ensure that the ->fini function pointer is not yet invoked before the cancel is completed. As the cancel operation may potentially invoke crypto operations, the cipher state must be available. * patch 04: deallocate Jitter RNG after nonblocking_pool is fully initialized. The change implies that regardless of the state of the nonblocking_pool, the Jitter RNG is used for the initial seeding in any case and only dropped for later reseeding operations. Changes v6: * patch 01: simplify patch by just adding a blocking API call to random.c as suggested by Herbert Xu. * patch 03: move the async operation into this patch: the DRBG is in control of the async work. Changes v5: * drop patch 01 and therefore drop the creation of a kernel pool * change patch 02 to use the nonblocking pool and block until the nonblocking pool is initialized or until the cancel operation is triggered. Changes v4: * Patch 02: Change get_blocking_random_bytes_cb to allow callers to call it multiple times without re-initializing the work data structure. Furthermore, only change the pointers to the output buffer and callback if work is not pending to avoid race conditions. * Patch 04: No canceling of seeding during drbg_seed as the invocation of get_blocking_random_bytes_cb can now be done repeatedly without re-initializing the work data structure. Changes v3: * Patch 01: Correct calculation of entropy count as pointed out by Herbert Xu * Patch 06: Correct a trivial coding issue in jent_entropy_init for checking JENT_EMINVARVAR reported by cppcheck Changes v2: * Use Dual BSD/GPL license in MODULE_LICENSE as suggested by Paul Bolle <pebolle@xxxxxxxxxx> * Patch 05, drbg_dealloc_state: only deallocate Jitter RNG if one was instantiated in the first place. There are two main reasons why the Jitter RNG may not be allocated: either it is not available as kernel module/in vmlinuz or during init time of the Jitter RNG, the performed testing shows that the underlying hardware is not suitable for the Jitter RNG (e.g. has a too coarse timer). [1] http://www.mail-archive.com/linux-crypto@xxxxxxxxxxxxxxx/msg13891.html [2] http://www.chronox.de/jent.html Stephan Mueller (5): random: Blocking API for accessing nonblocking_pool crypto: drbg - prepare for async seeding crypto: drbg - add async seeding operation crypto: drbg - use Jitter RNG to obtain seed crypto: add jitterentropy RNG crypto/Kconfig | 10 + crypto/Makefile | 2 + crypto/drbg.c | 146 ++++++-- crypto/jitterentropy.c | 909 +++++++++++++++++++++++++++++++++++++++++++++++++ crypto/testmgr.c | 4 + drivers/char/random.c | 20 ++ include/crypto/drbg.h | 5 + include/linux/random.h | 1 + 8 files changed, 1070 insertions(+), 27 deletions(-) create mode 100644 crypto/jitterentropy.c -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
