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Fortuna: Add failpoints to simulate initial seeding conditions

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Set debug.fail_point.random_fortuna_pre_read=return(1) and
debug.fail_point.random_fortuna_seeded=return(1) to return to unseeded
status (sort of).  See the Differential URL for more detail.

The goal is to reproduce e.g. Lev's recent CURRENT report[1] about failing
newfs arc4random(3) usage (fixed in r338542).

No functional change when failpoints are not set.

[1]: https://lists.freebsd.org/pipermail/freebsd-current/2018-September/071067.html

Reported by:	lev
Reviewed by:	delphij, markm
Approved by:	secteam (delphij)
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D17047
This commit is contained in:
Conrad Meyer 2018-10-26 21:03:57 +00:00
parent 7be4093a84
commit 9b8d0fe462
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=339790
1 changed files with 21 additions and 0 deletions
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21
sys/dev/random/fortuna.c
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@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
#ifdef _KERNEL
#include <sys/param.h>
#include <sys/fail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
@ -384,6 +385,18 @@ random_fortuna_pre_read(void)
return;
}
#ifdef _KERNEL
/*
* When set, pretend we do not have enough entropy to reseed yet.
*/
KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_pre_read, {
if (RETURN_VALUE != 0) {
RANDOM_RESEED_UNLOCK();
return;
}
});
#endif
#ifdef _KERNEL
fortuna_state.fs_lasttime = now;
#endif
@ -442,5 +455,13 @@ bool
random_fortuna_seeded(void)
{
#ifdef _KERNEL
/* When set, act as if we are not seeded. */
KFAIL_POINT_CODE(DEBUG_FP, random_fortuna_seeded, {
if (RETURN_VALUE != 0)
fortuna_state.fs_counter = UINT128_ZERO;
});
#endif
return (!uint128_is_zero(fortuna_state.fs_counter));
}