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authorNicolai Stange <nstange@suse.de>2021-11-15 15:18:04 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2021-11-26 16:16:49 +1100
commitce8ce31b2c5c8b18667784b8c515650c65d57b4e (patch)
treed9300e19b40d0452c7676885a5ff3d93a74b9460 /include/crypto
parent370a40ee228340b5141e5d89dee3186452d9f5fb (diff)
crypto: drbg - prepare for more fine-grained tracking of seeding state
There are two different randomness sources the DRBGs are getting seeded from, namely the jitterentropy source (if enabled) and get_random_bytes(). At initial DRBG seeding time during boot, the latter might not have collected sufficient entropy for seeding itself yet and thus, the DRBG implementation schedules a reseed work from a random_ready_callback once that has happened. This is particularly important for the !->pr DRBG instances, for which (almost) no further reseeds are getting triggered during their lifetime. Because collecting data from the jitterentropy source is a rather expensive operation, the aforementioned asynchronously scheduled reseed work restricts itself to get_random_bytes() only. That is, it in some sense amends the initial DRBG seed derived from jitterentropy output at full (estimated) entropy with fresh randomness obtained from get_random_bytes() once that has been seeded with sufficient entropy itself. With the advent of rng_is_initialized(), there is no real need for doing the reseed operation from an asynchronously scheduled work anymore and a subsequent patch will make it synchronous by moving it next to related logic already present in drbg_generate(). However, for tracking whether a full reseed including the jitterentropy source is required or a "partial" reseed involving only get_random_bytes() would be sufficient already, the boolean struct drbg_state's ->seeded member must become a tristate value. Prepare for this by introducing the new enum drbg_seed_state and change struct drbg_state's ->seeded member's type from bool to that type. For facilitating review, enum drbg_seed_state is made to only contain two members corresponding to the former ->seeded values of false and true resp. at this point: DRBG_SEED_STATE_UNSEEDED and DRBG_SEED_STATE_FULL. A third one for tracking the intermediate state of "seeded from jitterentropy only" will be introduced with a subsequent patch. There is no change in behaviour at this point. Signed-off-by: Nicolai Stange <nstange@suse.de> Reviewed-by: Stephan Müller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'include/crypto')
-rw-r--r--include/crypto/drbg.h7
1 files changed, 6 insertions, 1 deletions
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index c4165126937e..92a87b23ad2f 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h
@@ -105,6 +105,11 @@ struct drbg_test_data {
struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
};
+enum drbg_seed_state {
+ DRBG_SEED_STATE_UNSEEDED,
+ DRBG_SEED_STATE_FULL,
+};
+
struct drbg_state {
struct mutex drbg_mutex; /* lock around DRBG */
unsigned char *V; /* internal state 10.1.1.1 1a) */
@@ -127,7 +132,7 @@ struct drbg_state {
struct crypto_wait ctr_wait; /* CTR mode async wait obj */
struct scatterlist sg_in, sg_out; /* CTR mode SGLs */
- bool seeded; /* DRBG fully seeded? */
+ enum drbg_seed_state seeded; /* DRBG fully seeded? */
bool pr; /* Prediction resistance enabled? */
bool fips_primed; /* Continuous test primed? */
unsigned char *prev; /* FIPS 140-2 continuous test value */