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intruduce krb5_generate_random() that can fail and return an error, check for it at krb5_context creation time

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Love Hornquist Astrand
2013-10-21 08:22:02 -07:00
parent 1881980d44
commit 516c12c9a9
5 changed files with 89 additions and 13 deletions
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57
lib/krb5/crypto-rand.c
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@@ -33,6 +33,9 @@
#include "krb5_locl.h"
#undef HEIMDAL_WARN_UNUSED_RESULT_ATTRIBUTE
#define HEIMDAL_WARN_UNUSED_RESULT_ATTRIBUTE
#define ENTROPY_NEEDED 128
static HEIMDAL_MUTEX crypto_mutex = HEIMDAL_MUTEX_INITIALIZER;
@@ -94,20 +97,62 @@ seed_something(void)
return -1;
}
KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_generate_random_block(void *buf, size_t len)
/**
* Fill buffer buf with len bytes of PRNG randomness that is ok to use
* for key generation, padding and public diclosing the randomness w/o
* disclosing the randomness source.
*
* This function can fail, and callers must check the return value.
*
* @param buf a buffer to fill with randomness
* @param len length of memory that buf points to.
*
* @return return 0 on success or HEIM_ERR_RANDOM_OFFLINE if the
* funcation failed to initialize the randomness source.
*
* @ingroup krb5_crypto
*/
HEIMDAL_WARN_UNUSED_RESULT_ATTRIBUTE
KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_generate_random(void *buf, size_t len)
{
static int rng_initialized = 0;
int ret;
HEIMDAL_MUTEX_lock(&crypto_mutex);
if (!rng_initialized) {
if (seed_something())
krb5_abortx(NULL, "Fatal: could not seed the "
"random number generator");
return HEIM_ERR_RANDOM_OFFLINE;
rng_initialized = 1;
}
HEIMDAL_MUTEX_unlock(&crypto_mutex);
if (RAND_bytes(buf, len) <= 0)
ret = HEIM_ERR_RANDOM_OFFLINE;
else
ret = 0;
HEIMDAL_MUTEX_unlock(&crypto_mutex);
return ret;
}
/**
* Fill buffer buf with len bytes of PRNG randomness that is ok to use
* for key generation, padding and public diclosing the randomness w/o
* disclosing the randomness source.
*
* This function can NOT fail, instead it will abort() and program will crash.
*
* @param buf a buffer to fill with randomness
* @param len length of memory that buf points to.
*
* @ingroup krb5_crypto
*/
KRB5_LIB_FUNCTION void KRB5_LIB_CALL
krb5_generate_random_block(void *buf, size_t len)
{
int ret = krb5_generate_random(buf, len);
if (ret)
krb5_abortx(NULL, "Failed to generate random block");
}