git: 17dc7d3add57 - stable/12 - Fortuna: Add failpoints to simulate initial seeding conditions

[David E. O'Brien]

The branch stable/12 has been updated by obrien:

URL: https://cgit.FreeBSD.org/src/commit/?id=17dc7d3add57f8aa3bf5091644fb23d06a5b9c9f

commit 17dc7d3add57f8aa3bf5091644fb23d06a5b9c9f
Author:     Conrad Meyer <cem at FreeBSD.org>
AuthorDate: 2018-10-26 21:03:57 +0000
Commit:     David E. O'Brien <obrien at FreeBSD.org>
CommitDate: 2021-08-06 05:12:16 +0000

    Fortuna: Add failpoints to simulate initial seeding conditions
    
    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
    (cherry picked from commit 9b8d0fe462b2f3f689cb87fe34bd42c388e23d49)
---
 sys/dev/random/fortuna.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/sys/dev/random/fortuna.c b/sys/dev/random/fortuna.c
index 866899846212..3a46d527fa9a 100644
--- a/sys/dev/random/fortuna.c
+++ b/sys/dev/random/fortuna.c
@@ -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));
 }