Date: Sat, 26 Jan 2002 08:30:02 -0800 (PST) From: "Tim J. Robbins" <tim@robbins.dropbear.id.au> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/29741: ptrace(pid);ptrace(ppid) makes pid and ppid unkillable Message-ID: <200201261630.g0QGU2w95955@freefall.freebsd.org>
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The following reply was made to PR kern/29741; it has been noted by GNATS.
From: "Tim J. Robbins" <tim@robbins.dropbear.id.au>
To: freebsd-gnats-submit@FreeBSD.ORG
Cc: Dave Zarzycki <zarzycki@FreeBSD.ORG>
Subject: Re: kern/29741: ptrace(pid);ptrace(ppid) makes pid and ppid unkillable
Date: Sun, 27 Jan 2002 03:28:31 +1100
I can reproduce this problem with 4.5-RC. The problem seems to be that
ptrace() allows a process to attach to its owner. I've attached a patch
for both RELENG_4 and -CURRENT that seems to correct the problem. When
I try to reproduce it now:
tim@descent$ gdb -q
(gdb) file gdb
Reading symbols from gdb...(no debugging symbols found)...done.
(gdb) run -q
Starting program: /usr/bin/gdb -q
warning: shared library handler failed to enable breakpoint
Program received signal SIGTRAP, Trace/breakpoint trap.
0x2815e39c in ?? ()
(gdb) cont
Continuing.
(gdb) file gdb
Reading symbols from gdb...(no debugging symbols found)...done.
(gdb) attach 177
Attaching to program: /usr/bin/gdb, process 177
ptrace: Invalid argument.
I'm not exactly sure what the warning is about; it was there before I
mucked with ptrace.
Patch for RELENG_4:
Index: src/sys/kern/sys_process.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/sys_process.c,v
retrieving revision 1.51.2.3
diff -c -r1.51.2.3 sys_process.c
*** src/sys/kern/sys_process.c 2002/01/22 17:22:59 1.51.2.3
--- src/sys/kern/sys_process.c 2002/01/26 16:19:02
***************
*** 233,240 ****
break;
case PT_ATTACH:
! /* Self */
! if (p->p_pid == curp->p_pid)
return EINVAL;
/* Already traced */
--- 233,240 ----
break;
case PT_ATTACH:
! /* Self or owner */
! if (p->p_pid == curp->p_pid || p->p_pid == curp->p_oppid)
return EINVAL;
/* Already traced */
Patch for -CURRENT (not tested!):
Index: src/sys/kern/sys_process.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/sys_process.c,v
retrieving revision 1.76
diff -c -r1.76 sys_process.c
*** src/sys/kern/sys_process.c 2001/10/21 23:57:15 1.76
--- src/sys/kern/sys_process.c 2002/01/26 16:20:34
***************
*** 308,315 ****
break;
case PT_ATTACH:
! /* Self */
! if (p->p_pid == curp->p_pid) {
PROC_UNLOCK(p);
return (EINVAL);
}
--- 308,315 ----
break;
case PT_ATTACH:
! /* Self or owner */
! if (p->p_pid == curp->p_pid || p->p_pid == curp->p_oppid) {
PROC_UNLOCK(p);
return (EINVAL);
}
Tim
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