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diff --git a/lib/libc/sys/ptrace.2 b/lib/libc/sys/ptrace.2
--- a/lib/libc/sys/ptrace.2
+++ b/lib/libc/sys/ptrace.2
@@ -2,7 +2,7 @@
.\" $NetBSD: ptrace.2,v 1.2 1995/02/27 12:35:37 cgd Exp $
.\"
.\" This file is in the public domain.
-.Dd May 4, 2021
+.Dd May 20, 2021
.Dt PTRACE 2
.Os
.Sh NAME
@@ -99,6 +99,30 @@
signal.
All other additional signal stops use
.Dv SIGTRAP .
+.Sh DETACH AND TERMINATION
+.Pp
+Normally, exiting tracing process should wait for all pending
+debugging events and then detach from all alive traced processes
+before exiting using
+.Dv PT_DETACH
+request.
+If tracing process exits without detaching, for instance due to abnormal
+termination, the destiny of the traced children processes is determined
+by the
+.Dv kern.kill_on_debugger_exit
+sysctl control.
+.Pp
+If the control is set to the default value 1, such traced processes
+are terminated.
+If set to zero, kernel implicitly detaches traced processes.
+Traced processes are un-stopped if needed, and then continue the execution
+without tracing.
+Kernel drops any
+.Dv SIGTRAP
+signals queued to the traced children, which could be either generated by
+not yet consumed debug events, or sent by other means, the later should
+not be done anyway.
+.Sh TRACING EVENTS
.Pp
Each traced process has a tracing event mask.
An event in the traced process only reports a
@@ -216,6 +240,7 @@
.Dv PTRACE_EXEC
events.
All other event flags are disabled.
+.Sh PTRACE REQUESTS
.Pp
The
.Fa request
diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -66,6 +66,7 @@
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
+#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/ptrace.h>
#include <sys/acct.h> /* for acct_process() function prototype */
@@ -99,6 +100,11 @@
SDT_PROVIDER_DECLARE(proc);
SDT_PROBE_DEFINE1(proc, , , exit, "int");
+static int kern_kill_on_dbg_exit = 1;
+SYSCTL_INT(_kern, OID_AUTO, kill_on_debugger_exit, CTLFLAG_RWTUN,
+ &kern_kill_on_dbg_exit, 0,
+ "Kill ptraced processes when debugger exits");
+
struct proc *
proc_realparent(struct proc *child)
{
@@ -504,8 +510,9 @@
}
} else {
/*
- * Traced processes are killed since their existence
- * means someone is screwing up.
+ * Traced processes are killed by default
+ * since their existence means someone is
+ * screwing up.
*/
t = proc_realparent(q);
if (t == p) {
@@ -522,14 +529,23 @@
* orphan link for q now while q is locked.
*/
proc_clear_orphan(q);
- q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
+ q->p_flag &= ~P_TRACED;
q->p_flag2 &= ~P2_PTRACE_FSTP;
q->p_ptevents = 0;
+ p->p_xthread = NULL;
FOREACH_THREAD_IN_PROC(q, tdt) {
tdt->td_dbgflags &= ~(TDB_SUSPEND | TDB_XSIG |
TDB_FSTP);
+ tdt->td_xsig = 0;
+ }
+ if (kern_kill_on_dbg_exit) {
+ q->p_flag &= ~P_STOPPED_TRACE;
+ kern_psignal(q, SIGKILL);
+ } else if ((q->p_flag & (P_STOPPED_TRACE |
+ P_STOPPED_SIG)) != 0) {
+ sigqueue_delete_proc(q, SIGTRAP);
+ ptrace_unsuspend(q);
}
- kern_psignal(q, SIGKILL);
}
PROC_UNLOCK(q);
if (ksi != NULL)
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -610,6 +610,19 @@
p->p_ptevents = PTRACE_DEFAULT;
}
+void
+ptrace_unsuspend(struct proc *p)
+{
+ PROC_LOCK_ASSERT(p, MA_OWNED);
+
+ PROC_SLOCK(p);
+ p->p_flag &= ~(P_STOPPED_TRACE | P_STOPPED_SIG | P_WAITED);
+ thread_unsuspend(p);
+ PROC_SUNLOCK(p);
+ itimer_proc_continue(p);
+ kqtimer_proc_continue(p);
+}
+
static int
proc_can_ptrace(struct thread *td, struct proc *p)
{
@@ -1164,12 +1177,7 @@
* suspended, use PT_SUSPEND to suspend it before
* continuing the process.
*/
- PROC_SLOCK(p);
- p->p_flag &= ~(P_STOPPED_TRACE | P_STOPPED_SIG | P_WAITED);
- thread_unsuspend(p);
- PROC_SUNLOCK(p);
- itimer_proc_continue(p);
- kqtimer_proc_continue(p);
+ ptrace_unsuspend(p);
break;
case PT_WRITE_I:
diff --git a/sys/sys/ptrace.h b/sys/sys/ptrace.h
--- a/sys/sys/ptrace.h
+++ b/sys/sys/ptrace.h
@@ -240,6 +240,9 @@
int proc_read_dbregs32(struct thread *_td, struct dbreg32 *_dbreg32);
int proc_write_dbregs32(struct thread *_td, struct dbreg32 *_dbreg32);
#endif
+
+void ptrace_unsuspend(struct proc *p);
+
#else /* !_KERNEL */
#include <sys/cdefs.h>

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