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[src/trunk]: src/sys Add support for PTRACE_POSIX_SPAWN to report posix_spawn...
details: https://anonhg.NetBSD.org/src/rev/d7f65eb578d5
branches: trunk
changeset: 451909:d7f65eb578d5
user: kamil <kamil%NetBSD.org@localhost>
date: Tue Jun 11 23:18:55 2019 +0000
description:
Add support for PTRACE_POSIX_SPAWN to report posix_spawn(3) events
posix_spawn(3) is a first class syscall in NetBSD, different to
(V)FORK+EXEC as these operations are executed in one go. This differs to
Linux and FreeBSD, where posix_spawn(3) is implemented with existing kernel
primitives (clone(2), vfork(2), exec(3)) inside libc.
Typically LLDB and GDB software is aware of FORK/VFORK events. As discussed
with the LLDB community, instead of slicing the posix_spawn(3) operation
into phases emulating (V)FORK+EXEC(+VFORK_DONE) and returning intermediate
state to the debugger, that might have abnormal state, introduce new event
type: PTRACE_POSIX_SPAWN.
A debugger implementor can easily map it into existing fork+exec semantics
or treat as a distinct event.
There is no functional change for existing debuggers as there was no
support for reporting posix_spawn(3) events on the kernel side.
diffstat:
sys/kern/kern_exec.c | 77 +++++++++++++++++++++++++++++++++----------
sys/kern/kern_proc.c | 5 +-
sys/kern/sys_ptrace_common.c | 16 ++++++++-
sys/sys/proc.h | 5 ++-
sys/sys/ptrace.h | 3 +-
5 files changed, 81 insertions(+), 25 deletions(-)
diffs (truncated from 323 to 300 lines):
diff -r a01d9dc97ea6 -r d7f65eb578d5 sys/kern/kern_exec.c
--- a/sys/kern/kern_exec.c Tue Jun 11 17:26:09 2019 +0000
+++ b/sys/kern/kern_exec.c Tue Jun 11 23:18:55 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_exec.c,v 1.465 2019/05/09 20:50:14 kamil Exp $ */
+/* $NetBSD: kern_exec.c,v 1.466 2019/06/11 23:18:55 kamil Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -59,7 +59,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.465 2019/05/09 20:50:14 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.466 2019/06/11 23:18:55 kamil Exp $");
#include "opt_exec.h"
#include "opt_execfmt.h"
@@ -74,6 +74,7 @@
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/proc.h>
+#include <sys/ptrace.h>
#include <sys/mount.h>
#include <sys/kmem.h>
#include <sys/namei.h>
@@ -1269,7 +1270,8 @@
mutex_enter(proc_lock);
- if (p->p_slflag & PSL_TRACED) {
+ /* posix_spawn(3) reports a single event with implied exec(3) */
+ if ((p->p_slflag & PSL_TRACED) && !is_spawn) {
mutex_enter(p->p_lock);
eventswitch(TRAP_EXEC);
mutex_enter(proc_lock);
@@ -1984,6 +1986,7 @@
{
struct spawn_exec_data *spawn_data = arg;
struct lwp *l = curlwp;
+ struct proc *p = l->l_proc;
int error, newfd;
int ostat;
size_t i;
@@ -2013,7 +2016,7 @@
}
/* don't allow debugger access yet */
- rw_enter(&l->l_proc->p_reflock, RW_WRITER);
+ rw_enter(&p->p_reflock, RW_WRITER);
have_reflock = true;
error = 0;
@@ -2072,16 +2075,16 @@
* parent's p_nstopchild here. For safety, just make
* we're on the good side of SDEAD before we adjust.
*/
- ostat = l->l_proc->p_stat;
+ ostat = p->p_stat;
KASSERT(ostat < SSTOP);
- l->l_proc->p_stat = SSTOP;
- l->l_proc->p_waited = 0;
- l->l_proc->p_pptr->p_nstopchild++;
+ p->p_stat = SSTOP;
+ p->p_waited = 0;
+ p->p_pptr->p_nstopchild++;
mutex_exit(proc_lock);
/* Set process group */
if (spawn_data->sed_attrs->sa_flags & POSIX_SPAWN_SETPGROUP) {
- pid_t mypid = l->l_proc->p_pid,
+ pid_t mypid = p->p_pid,
pgrp = spawn_data->sed_attrs->sa_pgroup;
if (pgrp == 0)
@@ -2095,7 +2098,7 @@
/* Set scheduler policy */
if (spawn_data->sed_attrs->sa_flags & POSIX_SPAWN_SETSCHEDULER)
- error = do_sched_setparam(l->l_proc->p_pid, 0,
+ error = do_sched_setparam(p->p_pid, 0,
spawn_data->sed_attrs->sa_schedpolicy,
&spawn_data->sed_attrs->sa_schedparam);
else if (spawn_data->sed_attrs->sa_flags
@@ -2122,10 +2125,10 @@
/* Set signal masks/defaults */
if (spawn_data->sed_attrs->sa_flags & POSIX_SPAWN_SETSIGMASK) {
- mutex_enter(l->l_proc->p_lock);
+ mutex_enter(p->p_lock);
error = sigprocmask1(l, SIG_SETMASK,
&spawn_data->sed_attrs->sa_sigmask, NULL);
- mutex_exit(l->l_proc->p_lock);
+ mutex_exit(p->p_lock);
if (error)
goto report_error_stopped;
}
@@ -2149,8 +2152,8 @@
}
}
mutex_enter(proc_lock);
- l->l_proc->p_stat = ostat;
- l->l_proc->p_pptr->p_nstopchild--;
+ p->p_stat = ostat;
+ p->p_pptr->p_nstopchild--;
mutex_exit(proc_lock);
}
@@ -2172,6 +2175,19 @@
/* release our refcount on the data */
spawn_exec_data_release(spawn_data);
+ if (p->p_slflag & PSL_TRACED) {
+ /* Paranoid check */
+ mutex_enter(proc_lock);
+ if (!(p->p_slflag & PSL_TRACED)) {
+ mutex_exit(proc_lock);
+ goto cpu_return;
+ }
+
+ mutex_enter(p->p_lock);
+ eventswitch(TRAP_CHLD);
+ }
+
+ cpu_return:
/* and finally: leave to userland for the first time */
cpu_spawn_return(l);
@@ -2180,8 +2196,8 @@
report_error_stopped:
mutex_enter(proc_lock);
- l->l_proc->p_stat = ostat;
- l->l_proc->p_pptr->p_nstopchild--;
+ p->p_stat = ostat;
+ p->p_pptr->p_nstopchild--;
mutex_exit(proc_lock);
report_error:
if (have_reflock) {
@@ -2191,7 +2207,7 @@
* taken ownership of the sed_exec part of spawn_data,
* so release/free both here.
*/
- rw_exit(&l->l_proc->p_reflock);
+ rw_exit(&p->p_reflock);
execve_free_data(&spawn_data->sed_exec);
}
@@ -2209,7 +2225,7 @@
spawn_exec_data_release(spawn_data);
/* done, exit */
- mutex_enter(l->l_proc->p_lock);
+ mutex_enter(p->p_lock);
/*
* Posix explicitly asks for an exit code of 127 if we report
* errors from the child process - so, unfortunately, there
@@ -2545,6 +2561,13 @@
LIST_INSERT_HEAD(&p1->p_children, p2, p_sibling);
p2->p_exitsig = SIGCHLD; /* signal for parent on exit */
+ if ((p1->p_slflag & (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) ==
+ (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) {
+ proc_changeparent(p2, p1->p_pptr);
+ p1->p_pspid = p2->p_pid;
+ p2->p_pspid = p1->p_pid;
+ }
+
LIST_INSERT_AFTER(p1, p2, p_pglist);
LIST_INSERT_HEAD(&allproc, p2, p_list);
@@ -2582,7 +2605,23 @@
have_exec_lock = false;
*pid_res = pid;
- return error;
+
+ if (error)
+ return error;
+
+ if (p1->p_slflag & PSL_TRACED) {
+ /* Paranoid check */
+ mutex_enter(proc_lock);
+ if ((p1->p_slflag & (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) !=
+ (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) {
+ mutex_exit(proc_lock);
+ return 0;
+ }
+
+ mutex_enter(p1->p_lock);
+ eventswitch(TRAP_CHLD);
+ }
+ return 0;
error_exit:
if (have_exec_lock) {
diff -r a01d9dc97ea6 -r d7f65eb578d5 sys/kern/kern_proc.c
--- a/sys/kern/kern_proc.c Tue Jun 11 17:26:09 2019 +0000
+++ b/sys/kern/kern_proc.c Tue Jun 11 23:18:55 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_proc.c,v 1.232 2019/06/01 19:48:29 kamil Exp $ */
+/* $NetBSD: kern_proc.c,v 1.233 2019/06/11 23:18:55 kamil Exp $ */
/*-
* Copyright (c) 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.232 2019/06/01 19:48:29 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.233 2019/06/11 23:18:55 kamil Exp $");
#ifdef _KERNEL_OPT
#include "opt_kstack.h"
@@ -2266,6 +2266,7 @@
p->p_vfpid_done = psrc->p_vfpid_done;
p->p_lwp_created = psrc->p_lwp_created;
p->p_lwp_exited = psrc->p_lwp_exited;
+ p->p_pspid = psrc->p_pspid;
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 a01d9dc97ea6 -r d7f65eb578d5 sys/kern/sys_ptrace_common.c
--- a/sys/kern/sys_ptrace_common.c Tue Jun 11 17:26:09 2019 +0000
+++ b/sys/kern/sys_ptrace_common.c Tue Jun 11 23:18:55 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: sys_ptrace_common.c,v 1.54 2019/05/25 03:20:43 kamil Exp $ */
+/* $NetBSD: sys_ptrace_common.c,v 1.55 2019/06/11 23:18:55 kamil Exp $ */
/*-
* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -118,7 +118,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.54 2019/05/25 03:20:43 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.55 2019/06/11 23:18:55 kamil Exp $");
#ifdef _KERNEL_OPT
#include "opt_ptrace.h"
@@ -627,6 +627,8 @@
PTRACE_LWP_CREATE : 0;
pe.pe_set_event |= ISSET(t->p_slflag, PSL_TRACELWP_EXIT) ?
PTRACE_LWP_EXIT : 0;
+ pe.pe_set_event |= ISSET(t->p_slflag, PSL_TRACEPOSIX_SPAWN) ?
+ PTRACE_POSIX_SPAWN : 0;
DPRINTF(("%s: lwp=%d event=%#x\n", __func__,
t->p_sigctx.ps_lwp, pe.pe_set_event));
return copyout(&pe, addr, sizeof(pe));
@@ -671,6 +673,12 @@
SET(t->p_slflag, PSL_TRACELWP_EXIT);
else
CLR(t->p_slflag, PSL_TRACELWP_EXIT);
+
+ if (pe.pe_set_event & PTRACE_POSIX_SPAWN)
+ SET(t->p_slflag, PSL_TRACEPOSIX_SPAWN);
+ else
+ CLR(t->p_slflag, PSL_TRACEPOSIX_SPAWN);
+
return 0;
}
@@ -700,6 +708,9 @@
} else if (t->p_lwp_exited) {
ps.pe_report_event = PTRACE_LWP_EXIT;
ps.pe_lwp = t->p_lwp_exited;
+ } else if (t->p_pspid) {
+ ps.pe_report_event = PTRACE_POSIX_SPAWN;
+ ps.pe_other_pid = t->p_pspid;
}
DPRINTF(("%s: lwp=%d event=%#x pid=%d lwp=%d\n", __func__,
t->p_sigctx.ps_lwp, ps.pe_report_event,
@@ -885,6 +896,7 @@
t->p_vfpid_done = 0;
t->p_lwp_created = 0;
t->p_lwp_exited = 0;
+ t->p_pspid = 0;
/* Finally, deliver the requested signal (or none). */
if (t->p_stat == SSTOP) {
diff -r a01d9dc97ea6 -r d7f65eb578d5 sys/sys/proc.h
--- a/sys/sys/proc.h Tue Jun 11 17:26:09 2019 +0000
+++ b/sys/sys/proc.h Tue Jun 11 23:18:55 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: proc.h,v 1.352 2019/04/06 11:54:21 kamil Exp $ */
+/* $NetBSD: proc.h,v 1.353 2019/06/11 23:18:55 kamil Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -316,6 +316,7 @@
pid_t p_vfpid_done; /* :: vforked done pid */
lwpid_t p_lwp_created; /* :: lwp created */
lwpid_t p_lwp_exited; /* :: lwp exited */
+ pid_t p_pspid; /* :: posix_spawn pid */
char *p_path; /* :: full pathname of executable */
/*
@@ -411,6 +412,8 @@
0x00000008 /* traced process wants LWP create events */
#define PSL_TRACELWP_EXIT \
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