[src/trunk]: src/sys Reintroduce struct proc::p_oppid

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f2d820f79461
branches:  trunk
changeset: 970895:f2d820f79461
user:      kamil <kamil%NetBSD.org@localhost>
date:      Mon Apr 06 08:20:05 2020 +0000

description:
Reintroduce struct proc::p_oppid

Relying on p_opptr is not safe as there is a race between:
 - spawner giving a birth to a child process and being killed
 - spawnee accessng p_opptr and reporting TRAP_CHLD

PR kern/54786 by Andreas Gustafsson

diffstat:

 sys/kern/kern_exec.c |  5 +++--
 sys/kern/kern_fork.c |  8 +++++---
 sys/kern/kern_proc.c |  5 +++--
 sys/kern/kern_sig.c  |  8 ++++----
 sys/sys/proc.h       |  3 ++-
 5 files changed, 17 insertions(+), 12 deletions(-)

diffs (132 lines):

diff -r 3651cb77eea1 -r f2d820f79461 sys/kern/kern_exec.c
--- a/sys/kern/kern_exec.c      Mon Apr 06 06:41:34 2020 +0000
+++ b/sys/kern/kern_exec.c      Mon Apr 06 08:20:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_exec.c,v 1.494 2020/04/05 20:53:17 christos Exp $ */
+/*     $NetBSD: kern_exec.c,v 1.495 2020/04/06 08:20:05 kamil Exp $    */
 
 /*-
  * Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.494 2020/04/05 20:53:17 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.495 2020/04/06 08:20:05 kamil Exp $");
 
 #include "opt_exec.h"
 #include "opt_execfmt.h"
@@ -2660,6 +2660,7 @@
        if ((p1->p_slflag & (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) ==
            (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) {
                proc_changeparent(p2, p1->p_pptr);
+               p2->p_oppid = p1->p_pid;
        }
 
        LIST_INSERT_AFTER(p1, p2, p_pglist);
diff -r 3651cb77eea1 -r f2d820f79461 sys/kern/kern_fork.c
--- a/sys/kern/kern_fork.c      Mon Apr 06 06:41:34 2020 +0000
+++ b/sys/kern/kern_fork.c      Mon Apr 06 08:20:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_fork.c,v 1.220 2020/04/05 20:53:17 christos Exp $ */
+/*     $NetBSD: kern_fork.c,v 1.221 2020/04/06 08:20:05 kamil Exp $    */
 
 /*-
  * Copyright (c) 1999, 2001, 2004, 2006, 2007, 2008, 2019
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.220 2020/04/05 20:53:17 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.221 2020/04/06 08:20:05 kamil Exp $");
 
 #include "opt_ktrace.h"
 #include "opt_dtrace.h"
@@ -511,8 +511,10 @@
        /*
         * Trace fork(2) and vfork(2)-like events on demand in a debugger.
         */
-       if (tracefork(p1, flags) || tracevfork(p1, flags))
+       if (tracefork(p1, flags) || tracevfork(p1, flags)) {
                proc_changeparent(p2, p1->p_pptr);
+               p2->p_oppid = p1->p_pid;
+       }
 
        LIST_INSERT_AFTER(p1, p2, p_pglist);
        LIST_INSERT_HEAD(&allproc, p2, p_list);
diff -r 3651cb77eea1 -r f2d820f79461 sys/kern/kern_proc.c
--- a/sys/kern/kern_proc.c      Mon Apr 06 06:41:34 2020 +0000
+++ b/sys/kern/kern_proc.c      Mon Apr 06 08:20:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_proc.c,v 1.242 2020/02/23 22:14:03 ad Exp $       */
+/*     $NetBSD: kern_proc.c,v 1.243 2020/04/06 08:20:05 kamil Exp $    */
 
 /*-
  * Copyright (c) 1999, 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.242 2020/02/23 22:14:03 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.243 2020/04/06 08:20:05 kamil Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_kstack.h"
@@ -2270,6 +2270,7 @@
        COND_SET_VALUE(p->p_sigpend, psrc->p_sigpend, allowaddr);
        COND_SET_VALUE(p->p_lwpctl, psrc->p_lwpctl, allowaddr);
        p->p_ppid = psrc->p_ppid;
+       p->p_oppid = psrc->p_oppid;
        COND_SET_VALUE(p->p_path, psrc->p_path, allowaddr);
        COND_SET_VALUE(p->p_sigctx, psrc->p_sigctx, allowaddr);
        p->p_nice = psrc->p_nice;
diff -r 3651cb77eea1 -r f2d820f79461 sys/kern/kern_sig.c
--- a/sys/kern/kern_sig.c       Mon Apr 06 06:41:34 2020 +0000
+++ b/sys/kern/kern_sig.c       Mon Apr 06 08:20:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_sig.c,v 1.386 2020/04/05 20:53:17 christos Exp $  */
+/*     $NetBSD: kern_sig.c,v 1.387 2020/04/06 08:20:05 kamil Exp $     */
 
 /*-
  * Copyright (c) 2006, 2007, 2008, 2019 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.386 2020/04/05 20:53:17 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.387 2020/04/06 08:20:05 kamil Exp $");
 
 #include "opt_ptrace.h"
 #include "opt_dtrace.h"
@@ -1693,12 +1693,12 @@
 {
        mutex_enter(proc_lock);
        mutex_enter(p->p_lock);
-       if (!(p->p_slflag & PSL_TRACED) || p->p_opptr == NULL) {
+       if (!(p->p_slflag & PSL_TRACED)) {
                mutex_exit(p->p_lock);
                mutex_exit(proc_lock);
                return;
        }
-       eventswitch(code, pe_report_event, p->p_opptr->p_pid);
+       eventswitch(code, pe_report_event, p->p_oppid);
 }
 
 /*
diff -r 3651cb77eea1 -r f2d820f79461 sys/sys/proc.h
--- a/sys/sys/proc.h    Mon Apr 06 06:41:34 2020 +0000
+++ b/sys/sys/proc.h    Mon Apr 06 08:20:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: proc.h,v 1.361 2020/04/05 20:53:46 christos Exp $      */
+/*     $NetBSD: proc.h,v 1.362 2020/04/06 08:20:05 kamil Exp $ */
 
 /*-
  * Copyright (c) 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@@ -311,6 +311,7 @@
        sigpend_t       p_sigpend;      /* p: pending signals */
        struct lcproc   *p_lwpctl;      /* p, a: _lwp_ctl() information */
        pid_t           p_ppid;         /* :: cached parent pid */
+       pid_t           p_oppid;        /* :: cached original parent pid */
        char            *p_path;        /* :: full pathname of executable */
 
 /*