1174 lines
29 KiB
C
1174 lines
29 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1982, 1986, 1989, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ktrace.h"
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#include "opt_kstack_pages.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bitstring.h>
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#include <sys/sysproto.h>
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#include <sys/eventhandler.h>
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#include <sys/fcntl.h>
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#include <sys/filedesc.h>
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#include <sys/jail.h>
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#include <sys/kernel.h>
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#include <sys/kthread.h>
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#include <sys/sysctl.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/msan.h>
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#include <sys/mutex.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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#include <sys/procdesc.h>
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#include <sys/ptrace.h>
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#include <sys/racct.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/syscall.h>
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#include <sys/vmmeter.h>
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#include <sys/vnode.h>
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#include <sys/acct.h>
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#include <sys/ktr.h>
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#include <sys/ktrace.h>
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#include <sys/unistd.h>
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#include <sys/sdt.h>
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#include <sys/sx.h>
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#include <sys/sysent.h>
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#include <sys/signalvar.h>
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#include <security/audit/audit.h>
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#include <security/mac/mac_framework.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <vm/vm_extern.h>
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#include <vm/uma.h>
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#ifdef KDTRACE_HOOKS
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#include <sys/dtrace_bsd.h>
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dtrace_fork_func_t dtrace_fasttrap_fork;
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#endif
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SDT_PROVIDER_DECLARE(proc);
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SDT_PROBE_DEFINE3(proc, , , create, "struct proc *", "struct proc *", "int");
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#ifndef _SYS_SYSPROTO_H_
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struct fork_args {
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int dummy;
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};
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#endif
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/* ARGSUSED */
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int
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sys_fork(struct thread *td, struct fork_args *uap)
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{
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struct fork_req fr;
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int error, pid;
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bzero(&fr, sizeof(fr));
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fr.fr_flags = RFFDG | RFPROC;
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fr.fr_pidp = &pid;
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error = fork1(td, &fr);
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if (error == 0) {
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td->td_retval[0] = pid;
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td->td_retval[1] = 0;
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}
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return (error);
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}
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/* ARGUSED */
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int
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sys_pdfork(struct thread *td, struct pdfork_args *uap)
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{
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struct fork_req fr;
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int error, fd, pid;
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bzero(&fr, sizeof(fr));
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fr.fr_flags = RFFDG | RFPROC | RFPROCDESC;
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fr.fr_pidp = &pid;
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fr.fr_pd_fd = &fd;
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fr.fr_pd_flags = uap->flags;
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AUDIT_ARG_FFLAGS(uap->flags);
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/*
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* It is necessary to return fd by reference because 0 is a valid file
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* descriptor number, and the child needs to be able to distinguish
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* itself from the parent using the return value.
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*/
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error = fork1(td, &fr);
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if (error == 0) {
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td->td_retval[0] = pid;
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td->td_retval[1] = 0;
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error = copyout(&fd, uap->fdp, sizeof(fd));
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}
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return (error);
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}
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/* ARGSUSED */
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int
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sys_vfork(struct thread *td, struct vfork_args *uap)
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{
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struct fork_req fr;
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int error, pid;
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bzero(&fr, sizeof(fr));
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fr.fr_flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
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fr.fr_pidp = &pid;
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error = fork1(td, &fr);
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if (error == 0) {
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td->td_retval[0] = pid;
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td->td_retval[1] = 0;
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}
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return (error);
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}
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int
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sys_rfork(struct thread *td, struct rfork_args *uap)
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{
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struct fork_req fr;
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int error, pid;
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/* Don't allow kernel-only flags. */
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if ((uap->flags & RFKERNELONLY) != 0)
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return (EINVAL);
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/* RFSPAWN must not appear with others */
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if ((uap->flags & RFSPAWN) != 0 && uap->flags != RFSPAWN)
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return (EINVAL);
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AUDIT_ARG_FFLAGS(uap->flags);
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bzero(&fr, sizeof(fr));
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if ((uap->flags & RFSPAWN) != 0) {
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fr.fr_flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
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fr.fr_flags2 = FR2_DROPSIG_CAUGHT;
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} else {
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fr.fr_flags = uap->flags;
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}
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fr.fr_pidp = &pid;
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error = fork1(td, &fr);
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if (error == 0) {
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td->td_retval[0] = pid;
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td->td_retval[1] = 0;
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}
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return (error);
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}
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int __exclusive_cache_line nprocs = 1; /* process 0 */
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int lastpid = 0;
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SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0,
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"Last used PID");
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/*
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* Random component to lastpid generation. We mix in a random factor to make
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* it a little harder to predict. We sanity check the modulus value to avoid
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* doing it in critical paths. Don't let it be too small or we pointlessly
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* waste randomness entropy, and don't let it be impossibly large. Using a
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* modulus that is too big causes a LOT more process table scans and slows
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* down fork processing as the pidchecked caching is defeated.
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*/
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static int randompid = 0;
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static int
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sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
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{
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int error, pid;
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error = sysctl_wire_old_buffer(req, sizeof(int));
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if (error != 0)
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return(error);
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sx_xlock(&allproc_lock);
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pid = randompid;
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error = sysctl_handle_int(oidp, &pid, 0, req);
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if (error == 0 && req->newptr != NULL) {
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if (pid == 0)
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randompid = 0;
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else if (pid == 1)
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/* generate a random PID modulus between 100 and 1123 */
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randompid = 100 + arc4random() % 1024;
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else if (pid < 0 || pid > pid_max - 100)
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/* out of range */
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randompid = pid_max - 100;
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else if (pid < 100)
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/* Make it reasonable */
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randompid = 100;
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else
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randompid = pid;
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}
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sx_xunlock(&allproc_lock);
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return (error);
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}
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SYSCTL_PROC(_kern, OID_AUTO, randompid,
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CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0,
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sysctl_kern_randompid, "I",
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"Random PID modulus. Special values: 0: disable, 1: choose random value");
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extern bitstr_t proc_id_pidmap;
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extern bitstr_t proc_id_grpidmap;
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extern bitstr_t proc_id_sessidmap;
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extern bitstr_t proc_id_reapmap;
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/*
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* Find an unused process ID
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*
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* If RFHIGHPID is set (used during system boot), do not allocate
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* low-numbered pids.
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*/
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static int
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fork_findpid(int flags)
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{
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pid_t result;
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int trypid, random;
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/*
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* Avoid calling arc4random with procid_lock held.
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*/
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random = 0;
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if (__predict_false(randompid))
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random = arc4random() % randompid;
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mtx_lock(&procid_lock);
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trypid = lastpid + 1;
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if (flags & RFHIGHPID) {
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if (trypid < 10)
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trypid = 10;
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} else {
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trypid += random;
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}
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retry:
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if (trypid >= pid_max)
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trypid = 2;
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bit_ffc_at(&proc_id_pidmap, trypid, pid_max, &result);
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if (result == -1) {
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KASSERT(trypid != 2, ("unexpectedly ran out of IDs"));
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trypid = 2;
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goto retry;
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}
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if (bit_test(&proc_id_grpidmap, result) ||
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bit_test(&proc_id_sessidmap, result) ||
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bit_test(&proc_id_reapmap, result)) {
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trypid = result + 1;
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goto retry;
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}
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/*
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* RFHIGHPID does not mess with the lastpid counter during boot.
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*/
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if ((flags & RFHIGHPID) == 0)
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lastpid = result;
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bit_set(&proc_id_pidmap, result);
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mtx_unlock(&procid_lock);
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return (result);
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}
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static int
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fork_norfproc(struct thread *td, int flags)
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{
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int error;
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struct proc *p1;
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KASSERT((flags & RFPROC) == 0,
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("fork_norfproc called with RFPROC set"));
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p1 = td->td_proc;
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/*
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* Quiesce other threads if necessary. If RFMEM is not specified we
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* must ensure that other threads do not concurrently create a second
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* process sharing the vmspace, see vmspace_unshare().
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*/
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if ((p1->p_flag & (P_HADTHREADS | P_SYSTEM)) == P_HADTHREADS &&
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((flags & (RFCFDG | RFFDG)) != 0 || (flags & RFMEM) == 0)) {
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PROC_LOCK(p1);
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if (thread_single(p1, SINGLE_BOUNDARY)) {
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PROC_UNLOCK(p1);
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return (ERESTART);
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}
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PROC_UNLOCK(p1);
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}
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error = vm_forkproc(td, NULL, NULL, NULL, flags);
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if (error)
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goto fail;
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/*
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* Close all file descriptors.
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*/
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if (flags & RFCFDG) {
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struct filedesc *fdtmp;
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struct pwddesc *pdtmp;
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pdtmp = pdinit(td->td_proc->p_pd, false);
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fdtmp = fdinit();
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pdescfree(td);
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fdescfree(td);
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p1->p_fd = fdtmp;
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p1->p_pd = pdtmp;
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}
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/*
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* Unshare file descriptors (from parent).
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*/
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if (flags & RFFDG) {
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fdunshare(td);
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pdunshare(td);
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}
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fail:
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if ((p1->p_flag & (P_HADTHREADS | P_SYSTEM)) == P_HADTHREADS &&
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((flags & (RFCFDG | RFFDG)) != 0 || (flags & RFMEM) == 0)) {
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PROC_LOCK(p1);
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thread_single_end(p1, SINGLE_BOUNDARY);
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PROC_UNLOCK(p1);
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}
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return (error);
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}
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static void
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do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *td2,
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struct vmspace *vm2, struct file *fp_procdesc)
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{
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struct proc *p1, *pptr;
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struct filedesc *fd;
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struct filedesc_to_leader *fdtol;
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struct pwddesc *pd;
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struct sigacts *newsigacts;
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p1 = td->td_proc;
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PROC_LOCK(p1);
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bcopy(&p1->p_startcopy, &p2->p_startcopy,
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__rangeof(struct proc, p_startcopy, p_endcopy));
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pargs_hold(p2->p_args);
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PROC_UNLOCK(p1);
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bzero(&p2->p_startzero,
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__rangeof(struct proc, p_startzero, p_endzero));
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/* Tell the prison that we exist. */
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prison_proc_hold(p2->p_ucred->cr_prison);
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p2->p_state = PRS_NEW; /* protect against others */
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p2->p_pid = fork_findpid(fr->fr_flags);
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AUDIT_ARG_PID(p2->p_pid);
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TSFORK(p2->p_pid, p1->p_pid);
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sx_xlock(&allproc_lock);
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LIST_INSERT_HEAD(&allproc, p2, p_list);
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allproc_gen++;
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sx_xunlock(&allproc_lock);
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sx_xlock(PIDHASHLOCK(p2->p_pid));
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LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
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sx_xunlock(PIDHASHLOCK(p2->p_pid));
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tidhash_add(td2);
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|
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/*
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* Malloc things while we don't hold any locks.
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*/
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if (fr->fr_flags & RFSIGSHARE)
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newsigacts = NULL;
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else
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newsigacts = sigacts_alloc();
|
|
|
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/*
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* Copy filedesc.
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*/
|
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if (fr->fr_flags & RFCFDG) {
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pd = pdinit(p1->p_pd, false);
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fd = fdinit();
|
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fdtol = NULL;
|
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} else if (fr->fr_flags & RFFDG) {
|
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if (fr->fr_flags2 & FR2_SHARE_PATHS)
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pd = pdshare(p1->p_pd);
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else
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pd = pdcopy(p1->p_pd);
|
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fd = fdcopy(p1->p_fd);
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fdtol = NULL;
|
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} else {
|
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if (fr->fr_flags2 & FR2_SHARE_PATHS)
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pd = pdcopy(p1->p_pd);
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else
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pd = pdshare(p1->p_pd);
|
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fd = fdshare(p1->p_fd);
|
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if (p1->p_fdtol == NULL)
|
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p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL,
|
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p1->p_leader);
|
|
if ((fr->fr_flags & RFTHREAD) != 0) {
|
|
/*
|
|
* Shared file descriptor table, and shared
|
|
* process leaders.
|
|
*/
|
|
fdtol = p1->p_fdtol;
|
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FILEDESC_XLOCK(p1->p_fd);
|
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fdtol->fdl_refcount++;
|
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FILEDESC_XUNLOCK(p1->p_fd);
|
|
} else {
|
|
/*
|
|
* Shared file descriptor table, and different
|
|
* process leaders.
|
|
*/
|
|
fdtol = filedesc_to_leader_alloc(p1->p_fdtol,
|
|
p1->p_fd, p2);
|
|
}
|
|
}
|
|
/*
|
|
* Make a proc table entry for the new process.
|
|
* Start by zeroing the section of proc that is zero-initialized,
|
|
* then copy the section that is copied directly from the parent.
|
|
*/
|
|
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
bzero(&td2->td_startzero,
|
|
__rangeof(struct thread, td_startzero, td_endzero));
|
|
|
|
bcopy(&td->td_startcopy, &td2->td_startcopy,
|
|
__rangeof(struct thread, td_startcopy, td_endcopy));
|
|
|
|
bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name));
|
|
td2->td_sigstk = td->td_sigstk;
|
|
td2->td_flags = TDF_INMEM;
|
|
td2->td_lend_user_pri = PRI_MAX;
|
|
|
|
#ifdef VIMAGE
|
|
td2->td_vnet = NULL;
|
|
td2->td_vnet_lpush = NULL;
|
|
#endif
|
|
|
|
/*
|
|
* Allow the scheduler to initialize the child.
|
|
*/
|
|
thread_lock(td);
|
|
sched_fork(td, td2);
|
|
/*
|
|
* Request AST to check for TDP_RFPPWAIT. Do it here
|
|
* to avoid calling thread_lock() again.
|
|
*/
|
|
if ((fr->fr_flags & RFPPWAIT) != 0)
|
|
td->td_flags |= TDF_ASTPENDING;
|
|
thread_unlock(td);
|
|
|
|
/*
|
|
* Duplicate sub-structures as needed.
|
|
* Increase reference counts on shared objects.
|
|
*/
|
|
p2->p_flag = P_INMEM;
|
|
p2->p_flag2 = p1->p_flag2 & (P2_ASLR_DISABLE | P2_ASLR_ENABLE |
|
|
P2_ASLR_IGNSTART | P2_NOTRACE | P2_NOTRACE_EXEC |
|
|
P2_PROTMAX_ENABLE | P2_PROTMAX_DISABLE | P2_TRAPCAP |
|
|
P2_STKGAP_DISABLE | P2_STKGAP_DISABLE_EXEC | P2_NO_NEW_PRIVS |
|
|
P2_WXORX_DISABLE | P2_WXORX_ENABLE_EXEC);
|
|
p2->p_swtick = ticks;
|
|
if (p1->p_flag & P_PROFIL)
|
|
startprofclock(p2);
|
|
|
|
if (fr->fr_flags & RFSIGSHARE) {
|
|
p2->p_sigacts = sigacts_hold(p1->p_sigacts);
|
|
} else {
|
|
sigacts_copy(newsigacts, p1->p_sigacts);
|
|
p2->p_sigacts = newsigacts;
|
|
if ((fr->fr_flags2 & (FR2_DROPSIG_CAUGHT | FR2_KPROC)) != 0) {
|
|
mtx_lock(&p2->p_sigacts->ps_mtx);
|
|
if ((fr->fr_flags2 & FR2_DROPSIG_CAUGHT) != 0)
|
|
sig_drop_caught(p2);
|
|
if ((fr->fr_flags2 & FR2_KPROC) != 0)
|
|
p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
|
|
mtx_unlock(&p2->p_sigacts->ps_mtx);
|
|
}
|
|
}
|
|
|
|
if (fr->fr_flags & RFTSIGZMB)
|
|
p2->p_sigparent = RFTSIGNUM(fr->fr_flags);
|
|
else if (fr->fr_flags & RFLINUXTHPN)
|
|
p2->p_sigparent = SIGUSR1;
|
|
else
|
|
p2->p_sigparent = SIGCHLD;
|
|
|
|
if ((fr->fr_flags2 & FR2_KPROC) != 0) {
|
|
p2->p_flag |= P_SYSTEM | P_KPROC;
|
|
td2->td_pflags |= TDP_KTHREAD;
|
|
}
|
|
|
|
p2->p_textvp = p1->p_textvp;
|
|
p2->p_textdvp = p1->p_textdvp;
|
|
p2->p_fd = fd;
|
|
p2->p_fdtol = fdtol;
|
|
p2->p_pd = pd;
|
|
|
|
if (p1->p_flag2 & P2_INHERIT_PROTECTED) {
|
|
p2->p_flag |= P_PROTECTED;
|
|
p2->p_flag2 |= P2_INHERIT_PROTECTED;
|
|
}
|
|
|
|
/*
|
|
* p_limit is copy-on-write. Bump its refcount.
|
|
*/
|
|
lim_fork(p1, p2);
|
|
|
|
thread_cow_get_proc(td2, p2);
|
|
|
|
pstats_fork(p1->p_stats, p2->p_stats);
|
|
|
|
PROC_UNLOCK(p1);
|
|
PROC_UNLOCK(p2);
|
|
|
|
/*
|
|
* Bump references to the text vnode and directory, and copy
|
|
* the hardlink name.
|
|
*/
|
|
if (p2->p_textvp != NULL)
|
|
vrefact(p2->p_textvp);
|
|
if (p2->p_textdvp != NULL)
|
|
vrefact(p2->p_textdvp);
|
|
p2->p_binname = p1->p_binname == NULL ? NULL :
|
|
strdup(p1->p_binname, M_PARGS);
|
|
|
|
/*
|
|
* Set up linkage for kernel based threading.
|
|
*/
|
|
if ((fr->fr_flags & RFTHREAD) != 0) {
|
|
mtx_lock(&ppeers_lock);
|
|
p2->p_peers = p1->p_peers;
|
|
p1->p_peers = p2;
|
|
p2->p_leader = p1->p_leader;
|
|
mtx_unlock(&ppeers_lock);
|
|
PROC_LOCK(p1->p_leader);
|
|
if ((p1->p_leader->p_flag & P_WEXIT) != 0) {
|
|
PROC_UNLOCK(p1->p_leader);
|
|
/*
|
|
* The task leader is exiting, so process p1 is
|
|
* going to be killed shortly. Since p1 obviously
|
|
* isn't dead yet, we know that the leader is either
|
|
* sending SIGKILL's to all the processes in this
|
|
* task or is sleeping waiting for all the peers to
|
|
* exit. We let p1 complete the fork, but we need
|
|
* to go ahead and kill the new process p2 since
|
|
* the task leader may not get a chance to send
|
|
* SIGKILL to it. We leave it on the list so that
|
|
* the task leader will wait for this new process
|
|
* to commit suicide.
|
|
*/
|
|
PROC_LOCK(p2);
|
|
kern_psignal(p2, SIGKILL);
|
|
PROC_UNLOCK(p2);
|
|
} else
|
|
PROC_UNLOCK(p1->p_leader);
|
|
} else {
|
|
p2->p_peers = NULL;
|
|
p2->p_leader = p2;
|
|
}
|
|
|
|
sx_xlock(&proctree_lock);
|
|
PGRP_LOCK(p1->p_pgrp);
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
/*
|
|
* Preserve some more flags in subprocess. P_PROFIL has already
|
|
* been preserved.
|
|
*/
|
|
p2->p_flag |= p1->p_flag & P_SUGID;
|
|
td2->td_pflags |= (td->td_pflags & (TDP_ALTSTACK | TDP_SIGFASTBLOCK));
|
|
SESS_LOCK(p1->p_session);
|
|
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
|
|
p2->p_flag |= P_CONTROLT;
|
|
SESS_UNLOCK(p1->p_session);
|
|
if (fr->fr_flags & RFPPWAIT)
|
|
p2->p_flag |= P_PPWAIT;
|
|
|
|
p2->p_pgrp = p1->p_pgrp;
|
|
LIST_INSERT_AFTER(p1, p2, p_pglist);
|
|
PGRP_UNLOCK(p1->p_pgrp);
|
|
LIST_INIT(&p2->p_children);
|
|
LIST_INIT(&p2->p_orphans);
|
|
|
|
callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0);
|
|
TAILQ_INIT(&p2->p_kqtim_stop);
|
|
|
|
/*
|
|
* This begins the section where we must prevent the parent
|
|
* from being swapped.
|
|
*/
|
|
_PHOLD(p1);
|
|
PROC_UNLOCK(p1);
|
|
|
|
/*
|
|
* Attach the new process to its parent.
|
|
*
|
|
* If RFNOWAIT is set, the newly created process becomes a child
|
|
* of init. This effectively disassociates the child from the
|
|
* parent.
|
|
*/
|
|
if ((fr->fr_flags & RFNOWAIT) != 0) {
|
|
pptr = p1->p_reaper;
|
|
p2->p_reaper = pptr;
|
|
} else {
|
|
p2->p_reaper = (p1->p_treeflag & P_TREE_REAPER) != 0 ?
|
|
p1 : p1->p_reaper;
|
|
pptr = p1;
|
|
}
|
|
p2->p_pptr = pptr;
|
|
p2->p_oppid = pptr->p_pid;
|
|
LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
|
|
LIST_INIT(&p2->p_reaplist);
|
|
LIST_INSERT_HEAD(&p2->p_reaper->p_reaplist, p2, p_reapsibling);
|
|
if (p2->p_reaper == p1 && p1 != initproc) {
|
|
p2->p_reapsubtree = p2->p_pid;
|
|
proc_id_set_cond(PROC_ID_REAP, p2->p_pid);
|
|
}
|
|
sx_xunlock(&proctree_lock);
|
|
|
|
/* Inform accounting that we have forked. */
|
|
p2->p_acflag = AFORK;
|
|
PROC_UNLOCK(p2);
|
|
|
|
#ifdef KTRACE
|
|
ktrprocfork(p1, p2);
|
|
#endif
|
|
|
|
/*
|
|
* Finish creating the child process. It will return via a different
|
|
* execution path later. (ie: directly into user mode)
|
|
*/
|
|
vm_forkproc(td, p2, td2, vm2, fr->fr_flags);
|
|
|
|
if (fr->fr_flags == (RFFDG | RFPROC)) {
|
|
VM_CNT_INC(v_forks);
|
|
VM_CNT_ADD(v_forkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else if (fr->fr_flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
|
|
VM_CNT_INC(v_vforks);
|
|
VM_CNT_ADD(v_vforkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else if (p1 == &proc0) {
|
|
VM_CNT_INC(v_kthreads);
|
|
VM_CNT_ADD(v_kthreadpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else {
|
|
VM_CNT_INC(v_rforks);
|
|
VM_CNT_ADD(v_rforkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
}
|
|
|
|
/*
|
|
* Associate the process descriptor with the process before anything
|
|
* can happen that might cause that process to need the descriptor.
|
|
* However, don't do this until after fork(2) can no longer fail.
|
|
*/
|
|
if (fr->fr_flags & RFPROCDESC)
|
|
procdesc_new(p2, fr->fr_pd_flags);
|
|
|
|
/*
|
|
* Both processes are set up, now check if any loadable modules want
|
|
* to adjust anything.
|
|
*/
|
|
EVENTHANDLER_DIRECT_INVOKE(process_fork, p1, p2, fr->fr_flags);
|
|
|
|
/*
|
|
* Set the child start time and mark the process as being complete.
|
|
*/
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
microuptime(&p2->p_stats->p_start);
|
|
PROC_SLOCK(p2);
|
|
p2->p_state = PRS_NORMAL;
|
|
PROC_SUNLOCK(p2);
|
|
|
|
#ifdef KDTRACE_HOOKS
|
|
/*
|
|
* Tell the DTrace fasttrap provider about the new process so that any
|
|
* tracepoints inherited from the parent can be removed. We have to do
|
|
* this only after p_state is PRS_NORMAL since the fasttrap module will
|
|
* use pfind() later on.
|
|
*/
|
|
if ((fr->fr_flags & RFMEM) == 0 && dtrace_fasttrap_fork)
|
|
dtrace_fasttrap_fork(p1, p2);
|
|
#endif
|
|
if (fr->fr_flags & RFPPWAIT) {
|
|
td->td_pflags |= TDP_RFPPWAIT;
|
|
td->td_rfppwait_p = p2;
|
|
td->td_dbgflags |= TDB_VFORK;
|
|
}
|
|
PROC_UNLOCK(p2);
|
|
|
|
/*
|
|
* Tell any interested parties about the new process.
|
|
*/
|
|
knote_fork(p1->p_klist, p2->p_pid);
|
|
|
|
/*
|
|
* Now can be swapped.
|
|
*/
|
|
_PRELE(p1);
|
|
PROC_UNLOCK(p1);
|
|
SDT_PROBE3(proc, , , create, p2, p1, fr->fr_flags);
|
|
|
|
if (fr->fr_flags & RFPROCDESC) {
|
|
procdesc_finit(p2->p_procdesc, fp_procdesc);
|
|
fdrop(fp_procdesc, td);
|
|
}
|
|
|
|
/*
|
|
* Speculative check for PTRACE_FORK. PTRACE_FORK is not
|
|
* synced with forks in progress so it is OK if we miss it
|
|
* if being set atm.
|
|
*/
|
|
if ((p1->p_ptevents & PTRACE_FORK) != 0) {
|
|
sx_xlock(&proctree_lock);
|
|
PROC_LOCK(p2);
|
|
|
|
/*
|
|
* p1->p_ptevents & p1->p_pptr are protected by both
|
|
* process and proctree locks for modifications,
|
|
* so owning proctree_lock allows the race-free read.
|
|
*/
|
|
if ((p1->p_ptevents & PTRACE_FORK) != 0) {
|
|
/*
|
|
* Arrange for debugger to receive the fork event.
|
|
*
|
|
* We can report PL_FLAG_FORKED regardless of
|
|
* P_FOLLOWFORK settings, but it does not make a sense
|
|
* for runaway child.
|
|
*/
|
|
td->td_dbgflags |= TDB_FORK;
|
|
td->td_dbg_forked = p2->p_pid;
|
|
td2->td_dbgflags |= TDB_STOPATFORK;
|
|
proc_set_traced(p2, true);
|
|
CTR2(KTR_PTRACE,
|
|
"do_fork: attaching to new child pid %d: oppid %d",
|
|
p2->p_pid, p2->p_oppid);
|
|
proc_reparent(p2, p1->p_pptr, false);
|
|
}
|
|
PROC_UNLOCK(p2);
|
|
sx_xunlock(&proctree_lock);
|
|
}
|
|
|
|
racct_proc_fork_done(p2);
|
|
|
|
if ((fr->fr_flags & RFSTOPPED) == 0) {
|
|
if (fr->fr_pidp != NULL)
|
|
*fr->fr_pidp = p2->p_pid;
|
|
/*
|
|
* If RFSTOPPED not requested, make child runnable and
|
|
* add to run queue.
|
|
*/
|
|
thread_lock(td2);
|
|
TD_SET_CAN_RUN(td2);
|
|
sched_add(td2, SRQ_BORING);
|
|
} else {
|
|
*fr->fr_procp = p2;
|
|
}
|
|
}
|
|
|
|
void
|
|
fork_rfppwait(struct thread *td)
|
|
{
|
|
struct proc *p, *p2;
|
|
|
|
MPASS(td->td_pflags & TDP_RFPPWAIT);
|
|
|
|
p = td->td_proc;
|
|
/*
|
|
* Preserve synchronization semantics of vfork. If
|
|
* waiting for child to exec or exit, fork set
|
|
* P_PPWAIT on child, and there we sleep on our proc
|
|
* (in case of exit).
|
|
*
|
|
* Do it after the ptracestop() above is finished, to
|
|
* not block our debugger until child execs or exits
|
|
* to finish vfork wait.
|
|
*/
|
|
td->td_pflags &= ~TDP_RFPPWAIT;
|
|
p2 = td->td_rfppwait_p;
|
|
again:
|
|
PROC_LOCK(p2);
|
|
while (p2->p_flag & P_PPWAIT) {
|
|
PROC_LOCK(p);
|
|
if (thread_suspend_check_needed()) {
|
|
PROC_UNLOCK(p2);
|
|
thread_suspend_check(0);
|
|
PROC_UNLOCK(p);
|
|
goto again;
|
|
} else {
|
|
PROC_UNLOCK(p);
|
|
}
|
|
cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
|
|
}
|
|
PROC_UNLOCK(p2);
|
|
|
|
if (td->td_dbgflags & TDB_VFORK) {
|
|
PROC_LOCK(p);
|
|
if (p->p_ptevents & PTRACE_VFORK)
|
|
ptracestop(td, SIGTRAP, NULL);
|
|
td->td_dbgflags &= ~TDB_VFORK;
|
|
PROC_UNLOCK(p);
|
|
}
|
|
}
|
|
|
|
int
|
|
fork1(struct thread *td, struct fork_req *fr)
|
|
{
|
|
struct proc *p1, *newproc;
|
|
struct thread *td2;
|
|
struct vmspace *vm2;
|
|
struct ucred *cred;
|
|
struct file *fp_procdesc;
|
|
vm_ooffset_t mem_charged;
|
|
int error, nprocs_new;
|
|
static int curfail;
|
|
static struct timeval lastfail;
|
|
int flags, pages;
|
|
|
|
flags = fr->fr_flags;
|
|
pages = fr->fr_pages;
|
|
|
|
if ((flags & RFSTOPPED) != 0)
|
|
MPASS(fr->fr_procp != NULL && fr->fr_pidp == NULL);
|
|
else
|
|
MPASS(fr->fr_procp == NULL);
|
|
|
|
/* Check for the undefined or unimplemented flags. */
|
|
if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0)
|
|
return (EINVAL);
|
|
|
|
/* Signal value requires RFTSIGZMB. */
|
|
if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0)
|
|
return (EINVAL);
|
|
|
|
/* Can't copy and clear. */
|
|
if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
|
|
return (EINVAL);
|
|
|
|
/* Check the validity of the signal number. */
|
|
if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG)
|
|
return (EINVAL);
|
|
|
|
if ((flags & RFPROCDESC) != 0) {
|
|
/* Can't not create a process yet get a process descriptor. */
|
|
if ((flags & RFPROC) == 0)
|
|
return (EINVAL);
|
|
|
|
/* Must provide a place to put a procdesc if creating one. */
|
|
if (fr->fr_pd_fd == NULL)
|
|
return (EINVAL);
|
|
|
|
/* Check if we are using supported flags. */
|
|
if ((fr->fr_pd_flags & ~PD_ALLOWED_AT_FORK) != 0)
|
|
return (EINVAL);
|
|
}
|
|
|
|
p1 = td->td_proc;
|
|
|
|
/*
|
|
* Here we don't create a new process, but we divorce
|
|
* certain parts of a process from itself.
|
|
*/
|
|
if ((flags & RFPROC) == 0) {
|
|
if (fr->fr_procp != NULL)
|
|
*fr->fr_procp = NULL;
|
|
else if (fr->fr_pidp != NULL)
|
|
*fr->fr_pidp = 0;
|
|
return (fork_norfproc(td, flags));
|
|
}
|
|
|
|
fp_procdesc = NULL;
|
|
newproc = NULL;
|
|
vm2 = NULL;
|
|
|
|
/*
|
|
* Increment the nprocs resource before allocations occur.
|
|
* Although process entries are dynamically created, we still
|
|
* keep a global limit on the maximum number we will
|
|
* create. There are hard-limits as to the number of processes
|
|
* that can run, established by the KVA and memory usage for
|
|
* the process data.
|
|
*
|
|
* Don't allow a nonprivileged user to use the last ten
|
|
* processes; don't let root exceed the limit.
|
|
*/
|
|
nprocs_new = atomic_fetchadd_int(&nprocs, 1) + 1;
|
|
if (nprocs_new >= maxproc - 10) {
|
|
if (priv_check_cred(td->td_ucred, PRIV_MAXPROC) != 0 ||
|
|
nprocs_new >= maxproc) {
|
|
error = EAGAIN;
|
|
sx_xlock(&allproc_lock);
|
|
if (ppsratecheck(&lastfail, &curfail, 1)) {
|
|
printf("maxproc limit exceeded by uid %u "
|
|
"(pid %d); see tuning(7) and "
|
|
"login.conf(5)\n",
|
|
td->td_ucred->cr_ruid, p1->p_pid);
|
|
}
|
|
sx_xunlock(&allproc_lock);
|
|
goto fail2;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If required, create a process descriptor in the parent first; we
|
|
* will abandon it if something goes wrong. We don't finit() until
|
|
* later.
|
|
*/
|
|
if (flags & RFPROCDESC) {
|
|
error = procdesc_falloc(td, &fp_procdesc, fr->fr_pd_fd,
|
|
fr->fr_pd_flags, fr->fr_pd_fcaps);
|
|
if (error != 0)
|
|
goto fail2;
|
|
AUDIT_ARG_FD(*fr->fr_pd_fd);
|
|
}
|
|
|
|
mem_charged = 0;
|
|
if (pages == 0)
|
|
pages = kstack_pages;
|
|
/* Allocate new proc. */
|
|
newproc = uma_zalloc(proc_zone, M_WAITOK);
|
|
td2 = FIRST_THREAD_IN_PROC(newproc);
|
|
if (td2 == NULL) {
|
|
td2 = thread_alloc(pages);
|
|
if (td2 == NULL) {
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
proc_linkup(newproc, td2);
|
|
} else {
|
|
kmsan_thread_alloc(td2);
|
|
if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) {
|
|
if (td2->td_kstack != 0)
|
|
vm_thread_dispose(td2);
|
|
if (!thread_alloc_stack(td2, pages)) {
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
}
|
|
}
|
|
|
|
if ((flags & RFMEM) == 0) {
|
|
vm2 = vmspace_fork(p1->p_vmspace, &mem_charged);
|
|
if (vm2 == NULL) {
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
if (!swap_reserve(mem_charged)) {
|
|
/*
|
|
* The swap reservation failed. The accounting
|
|
* from the entries of the copied vm2 will be
|
|
* subtracted in vmspace_free(), so force the
|
|
* reservation there.
|
|
*/
|
|
swap_reserve_force(mem_charged);
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
} else
|
|
vm2 = NULL;
|
|
|
|
/*
|
|
* XXX: This is ugly; when we copy resource usage, we need to bump
|
|
* per-cred resource counters.
|
|
*/
|
|
proc_set_cred_init(newproc, td->td_ucred);
|
|
|
|
/*
|
|
* Initialize resource accounting for the child process.
|
|
*/
|
|
error = racct_proc_fork(p1, newproc);
|
|
if (error != 0) {
|
|
error = EAGAIN;
|
|
goto fail1;
|
|
}
|
|
|
|
#ifdef MAC
|
|
mac_proc_init(newproc);
|
|
#endif
|
|
newproc->p_klist = knlist_alloc(&newproc->p_mtx);
|
|
STAILQ_INIT(&newproc->p_ktr);
|
|
|
|
/*
|
|
* Increment the count of procs running with this uid. Don't allow
|
|
* a nonprivileged user to exceed their current limit.
|
|
*/
|
|
cred = td->td_ucred;
|
|
if (!chgproccnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPROC))) {
|
|
if (priv_check_cred(cred, PRIV_PROC_LIMIT) != 0)
|
|
goto fail0;
|
|
chgproccnt(cred->cr_ruidinfo, 1, 0);
|
|
}
|
|
|
|
do_fork(td, fr, newproc, td2, vm2, fp_procdesc);
|
|
return (0);
|
|
fail0:
|
|
error = EAGAIN;
|
|
#ifdef MAC
|
|
mac_proc_destroy(newproc);
|
|
#endif
|
|
racct_proc_exit(newproc);
|
|
fail1:
|
|
proc_unset_cred(newproc);
|
|
fail2:
|
|
if (vm2 != NULL)
|
|
vmspace_free(vm2);
|
|
uma_zfree(proc_zone, newproc);
|
|
if ((flags & RFPROCDESC) != 0 && fp_procdesc != NULL) {
|
|
fdclose(td, fp_procdesc, *fr->fr_pd_fd);
|
|
fdrop(fp_procdesc, td);
|
|
}
|
|
atomic_add_int(&nprocs, -1);
|
|
pause("fork", hz / 2);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Handle the return of a child process from fork1(). This function
|
|
* is called from the MD fork_trampoline() entry point.
|
|
*/
|
|
void
|
|
fork_exit(void (*callout)(void *, struct trapframe *), void *arg,
|
|
struct trapframe *frame)
|
|
{
|
|
struct proc *p;
|
|
struct thread *td;
|
|
struct thread *dtd;
|
|
|
|
kmsan_mark(frame, sizeof(*frame), KMSAN_STATE_INITED);
|
|
|
|
td = curthread;
|
|
p = td->td_proc;
|
|
KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new"));
|
|
|
|
CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)",
|
|
td, td_get_sched(td), p->p_pid, td->td_name);
|
|
|
|
sched_fork_exit(td);
|
|
/*
|
|
* Processes normally resume in mi_switch() after being
|
|
* cpu_switch()'ed to, but when children start up they arrive here
|
|
* instead, so we must do much the same things as mi_switch() would.
|
|
*/
|
|
if ((dtd = PCPU_GET(deadthread))) {
|
|
PCPU_SET(deadthread, NULL);
|
|
thread_stash(dtd);
|
|
}
|
|
thread_unlock(td);
|
|
|
|
/*
|
|
* cpu_fork_kthread_handler intercepts this function call to
|
|
* have this call a non-return function to stay in kernel mode.
|
|
* initproc has its own fork handler, but it does return.
|
|
*/
|
|
KASSERT(callout != NULL, ("NULL callout in fork_exit"));
|
|
callout(arg, frame);
|
|
|
|
/*
|
|
* Check if a kernel thread misbehaved and returned from its main
|
|
* function.
|
|
*/
|
|
if (p->p_flag & P_KPROC) {
|
|
printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n",
|
|
td->td_name, p->p_pid);
|
|
kthread_exit();
|
|
}
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
|
|
if (p->p_sysent->sv_schedtail != NULL)
|
|
(p->p_sysent->sv_schedtail)(td);
|
|
}
|
|
|
|
/*
|
|
* Simplified back end of syscall(), used when returning from fork()
|
|
* directly into user mode. This function is passed in to fork_exit()
|
|
* as the first parameter and is called when returning to a new
|
|
* userland process.
|
|
*/
|
|
void
|
|
fork_return(struct thread *td, struct trapframe *frame)
|
|
{
|
|
struct proc *p;
|
|
|
|
p = td->td_proc;
|
|
if (td->td_dbgflags & TDB_STOPATFORK) {
|
|
PROC_LOCK(p);
|
|
if ((p->p_flag & P_TRACED) != 0) {
|
|
/*
|
|
* Inform the debugger if one is still present.
|
|
*/
|
|
td->td_dbgflags |= TDB_CHILD | TDB_SCX | TDB_FSTP;
|
|
ptracestop(td, SIGSTOP, NULL);
|
|
td->td_dbgflags &= ~(TDB_CHILD | TDB_SCX);
|
|
} else {
|
|
/*
|
|
* ... otherwise clear the request.
|
|
*/
|
|
td->td_dbgflags &= ~TDB_STOPATFORK;
|
|
}
|
|
PROC_UNLOCK(p);
|
|
} else if (p->p_flag & P_TRACED || td->td_dbgflags & TDB_BORN) {
|
|
/*
|
|
* This is the start of a new thread in a traced
|
|
* process. Report a system call exit event.
|
|
*/
|
|
PROC_LOCK(p);
|
|
td->td_dbgflags |= TDB_SCX;
|
|
if ((p->p_ptevents & PTRACE_SCX) != 0 ||
|
|
(td->td_dbgflags & TDB_BORN) != 0)
|
|
ptracestop(td, SIGTRAP, NULL);
|
|
td->td_dbgflags &= ~(TDB_SCX | TDB_BORN);
|
|
PROC_UNLOCK(p);
|
|
}
|
|
|
|
/*
|
|
* If the prison was killed mid-fork, die along with it.
|
|
*/
|
|
if (!prison_isalive(td->td_ucred->cr_prison))
|
|
exit1(td, 0, SIGKILL);
|
|
|
|
userret(td, frame);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_SYSRET))
|
|
ktrsysret(SYS_fork, 0, 0);
|
|
#endif
|
|
}
|