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sysctl: implement debug.kdb.panic_str

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This is just like debug.kdb.panic, except the string that's passed in
is reported in the panic message. This allows people with automated
systems to collect kernel panics over a large fleet of machines to
flag panics better. Strings like "Warner look at this hang" or "see
JIRA ABC-1234 for details" allow these automated systems to route the
forced panic to the appropriate engineers like you can with other
types of panics. Other users are likely possible.

Relnotes: Yes
Sponsored by: Netflix
Reviewed by: allanjude (earlier version)
Suggestions from review folded in by: 0mp, emaste, lwhsu
Differential Revision: https://reviews.freebsd.org/D28041
This commit is contained in:
Warner Losh 2021-01-08 09:34:31 -07:00
parent 7c6a71d16c
commit 936440560b
2 changed files with 23 additions and 2 deletions
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5
share/man/man7/security.7
View File

@ -28,7 +28,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd November 28, 2020
.Dd January 8, 2020
.Dt SECURITY 7
.Os
.Sh NAME
@ -539,7 +539,8 @@ The kernel debugger may not be entered using the
.Va debug.kdb.enter
sysctl.
A panic or trap cannot be forced using the
.Va debug.kdb.panic
.Va debug.kdb.panic ,
.Va debug.kdb.panic_str
and other sysctl's.
.It Ic 2
Highly secure mode \- same as secure mode, plus disks may not be

20
sys/kern/subr_kdb.c
View File

@ -82,6 +82,7 @@ static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS);
@ -109,6 +110,11 @@ SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
kdb_sysctl_panic, "I",
"set to panic the kernel");
SYSCTL_PROC(_debug_kdb, OID_AUTO, panic_str,
CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
kdb_sysctl_panic_str, "A",
"set to panic the kernel with using the string as the panic message");
SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_MPSAFE, NULL, 0,
kdb_sysctl_trap, "I",
@ -206,6 +212,20 @@ kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
return (0);
}
static int
kdb_sysctl_panic_str(SYSCTL_HANDLER_ARGS)
{
int error;
static char buf[256]; /* static buffer to limit mallocs when panicing */
*buf = '\0';
error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
if (error != 0 || req->newptr == NULL)
return (error);
panic("kdb_sysctl_panic: %s", buf);
return (0);
}
static int
kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
{