From 8405ec8e3c02df8b3720874c3e2169fef4553868 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stephan=20M=C3=BCller?= Date: Sat, 7 Oct 2023 09:10:43 +0200 Subject: [PATCH] crypto: jitter - reuse allocated entropy collector In case a health test error occurs during runtime, the power-up health tests are rerun to verify that the noise source is still good and that the reported health test error was an outlier. For performing this power-up health test, the already existing entropy collector instance is used instead of allocating a new one. This change has the following implications: * The noise that is collected as part of the newly run health tests is inserted into the entropy collector and thus stirs the existing data present in there further. Thus, the entropy collected during the health test is not wasted. This is also allowed by SP800-90B. * The power-on health test is not affected by the state of the entropy collector, because it resets the APT / RCT state. The remainder of the state is unrelated to the health test as it is only applied to newly obtained time stamps. This change also fixes a bug report about an allocation while in an atomic lock (the lock is taken in jent_kcapi_random, jent_read_entropy is called and this can call jent_entropy_init). Fixes: 04597c8dd6c4 ("jitter - add RCT/APT support for different OSRs") Reported-by: Dan Carpenter Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/jitterentropy-kcapi.c | 2 +- crypto/jitterentropy.c | 34 +++++++++++++++++++++++++--------- crypto/jitterentropy.h | 2 +- 3 files changed, 27 insertions(+), 11 deletions(-) diff --git a/crypto/jitterentropy-kcapi.c b/crypto/jitterentropy-kcapi.c index 0c6752221451..76edbf8af0ac 100644 --- a/crypto/jitterentropy-kcapi.c +++ b/crypto/jitterentropy-kcapi.c @@ -347,7 +347,7 @@ static int __init jent_mod_init(void) desc->tfm = tfm; crypto_shash_init(desc); - ret = jent_entropy_init(CONFIG_CRYPTO_JITTERENTROPY_OSR, 0, desc); + ret = jent_entropy_init(CONFIG_CRYPTO_JITTERENTROPY_OSR, 0, desc, NULL); shash_desc_zero(desc); crypto_free_shash(tfm); if (ret) { diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c index 18bbe2b89a94..09c9db90c154 100644 --- a/crypto/jitterentropy.c +++ b/crypto/jitterentropy.c @@ -611,8 +611,7 @@ int jent_read_entropy(struct rand_data *ec, unsigned char *data, * Perform startup health tests and return permanent * error if it fails. */ - if (jent_entropy_init(ec->osr, ec->flags, - ec->hash_state)) + if (jent_entropy_init(0, 0, NULL, ec)) return -3; return -2; @@ -686,14 +685,30 @@ void jent_entropy_collector_free(struct rand_data *entropy_collector) jent_zfree(entropy_collector); } -int jent_entropy_init(unsigned int osr, unsigned int flags, void *hash_state) +int jent_entropy_init(unsigned int osr, unsigned int flags, void *hash_state, + struct rand_data *p_ec) { - struct rand_data *ec; - int i, time_backwards = 0, ret = 0; + /* + * If caller provides an allocated ec, reuse it which implies that the + * health test entropy data is used to further still the available + * entropy pool. + */ + struct rand_data *ec = p_ec; + int i, time_backwards = 0, ret = 0, ec_free = 0; - ec = jent_entropy_collector_alloc(osr, flags, hash_state); - if (!ec) - return JENT_EMEM; + if (!ec) { + ec = jent_entropy_collector_alloc(osr, flags, hash_state); + if (!ec) + return JENT_EMEM; + ec_free = 1; + } else { + /* Reset the APT */ + jent_apt_reset(ec, 0); + /* Ensure that a new APT base is obtained */ + ec->apt_base_set = 0; + /* Reset the RCT */ + ec->rct_count = 0; + } /* We could perform statistical tests here, but the problem is * that we only have a few loop counts to do testing. These @@ -783,7 +798,8 @@ int jent_entropy_init(unsigned int osr, unsigned int flags, void *hash_state) } out: - jent_entropy_collector_free(ec); + if (ec_free) + jent_entropy_collector_free(ec); return ret; } diff --git a/crypto/jitterentropy.h b/crypto/jitterentropy.h index e31661ee00d3..aa4728675ae2 100644 --- a/crypto/jitterentropy.h +++ b/crypto/jitterentropy.h @@ -12,7 +12,7 @@ int jent_read_random_block(void *hash_state, char *dst, unsigned int dst_len); struct rand_data; extern int jent_entropy_init(unsigned int osr, unsigned int flags, - void *hash_state); + void *hash_state, struct rand_data *p_ec); extern int jent_read_entropy(struct rand_data *ec, unsigned char *data, unsigned int len);