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-rw-r--r--sys/kern/kern_fork.c1052
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diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
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--- /dev/null
+++ b/sys/kern/kern_fork.c
@@ -0,0 +1,1052 @@
+/*-
+ * Copyright (c) 1982, 1986, 1989, 1991, 1993
+ * The Regents of the University of California. All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_kdtrace.h"
+#include "opt_ktrace.h"
+#include "opt_kstack_pages.h"
+#include "opt_procdesc.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/sysproto.h>
+#include <sys/eventhandler.h>
+#include <sys/fcntl.h>
+#include <sys/filedesc.h>
+#include <sys/jail.h>
+#include <sys/kernel.h>
+#include <sys/kthread.h>
+#include <sys/sysctl.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/priv.h>
+#include <sys/proc.h>
+#include <sys/procdesc.h>
+#include <sys/pioctl.h>
+#include <sys/racct.h>
+#include <sys/resourcevar.h>
+#include <sys/sched.h>
+#include <sys/syscall.h>
+#include <sys/vmmeter.h>
+#include <sys/vnode.h>
+#include <sys/acct.h>
+#include <sys/ktr.h>
+#include <sys/ktrace.h>
+#include <sys/unistd.h>
+#include <sys/sdt.h>
+#include <sys/sx.h>
+#include <sys/sysent.h>
+#include <sys/signalvar.h>
+
+#include <security/audit/audit.h>
+#include <security/mac/mac_framework.h>
+
+#include <vm/vm.h>
+#include <vm/pmap.h>
+#include <vm/vm_map.h>
+#include <vm/vm_extern.h>
+#include <vm/uma.h>
+
+#ifdef KDTRACE_HOOKS
+#include <sys/dtrace_bsd.h>
+dtrace_fork_func_t dtrace_fasttrap_fork;
+#endif
+
+SDT_PROVIDER_DECLARE(proc);
+SDT_PROBE_DEFINE3(proc, kernel, , create, create, "struct proc *",
+ "struct proc *", "int");
+
+#ifndef _SYS_SYSPROTO_H_
+struct fork_args {
+ int dummy;
+};
+#endif
+
+/* ARGSUSED */
+int
+sys_fork(struct thread *td, struct fork_args *uap)
+{
+ int error;
+ struct proc *p2;
+
+ error = fork1(td, RFFDG | RFPROC, 0, &p2, NULL, 0);
+ if (error == 0) {
+ td->td_retval[0] = p2->p_pid;
+ td->td_retval[1] = 0;
+ }
+ return (error);
+}
+
+/* ARGUSED */
+int
+sys_pdfork(td, uap)
+ struct thread *td;
+ struct pdfork_args *uap;
+{
+#ifdef PROCDESC
+ int error, fd;
+ struct proc *p2;
+
+ /*
+ * It is necessary to return fd by reference because 0 is a valid file
+ * descriptor number, and the child needs to be able to distinguish
+ * itself from the parent using the return value.
+ */
+ error = fork1(td, RFFDG | RFPROC | RFPROCDESC, 0, &p2,
+ &fd, uap->flags);
+ if (error == 0) {
+ td->td_retval[0] = p2->p_pid;
+ td->td_retval[1] = 0;
+ error = copyout(&fd, uap->fdp, sizeof(fd));
+ }
+ return (error);
+#else
+ return (ENOSYS);
+#endif
+}
+
+/* ARGSUSED */
+int
+sys_vfork(struct thread *td, struct vfork_args *uap)
+{
+ int error, flags;
+ struct proc *p2;
+
+ flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
+ error = fork1(td, flags, 0, &p2, NULL, 0);
+ if (error == 0) {
+ td->td_retval[0] = p2->p_pid;
+ td->td_retval[1] = 0;
+ }
+ return (error);
+}
+
+int
+sys_rfork(struct thread *td, struct rfork_args *uap)
+{
+ struct proc *p2;
+ int error;
+
+ /* Don't allow kernel-only flags. */
+ if ((uap->flags & RFKERNELONLY) != 0)
+ return (EINVAL);
+
+ AUDIT_ARG_FFLAGS(uap->flags);
+ error = fork1(td, uap->flags, 0, &p2, NULL, 0);
+ if (error == 0) {
+ td->td_retval[0] = p2 ? p2->p_pid : 0;
+ td->td_retval[1] = 0;
+ }
+ return (error);
+}
+
+int nprocs = 1; /* process 0 */
+int lastpid = 0;
+SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0,
+ "Last used PID");
+
+/*
+ * Random component to lastpid generation. We mix in a random factor to make
+ * it a little harder to predict. We sanity check the modulus value to avoid
+ * doing it in critical paths. Don't let it be too small or we pointlessly
+ * waste randomness entropy, and don't let it be impossibly large. Using a
+ * modulus that is too big causes a LOT more process table scans and slows
+ * down fork processing as the pidchecked caching is defeated.
+ */
+static int randompid = 0;
+
+static int
+sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
+{
+ int error, pid;
+
+ error = sysctl_wire_old_buffer(req, sizeof(int));
+ if (error != 0)
+ return(error);
+ sx_xlock(&allproc_lock);
+ pid = randompid;
+ error = sysctl_handle_int(oidp, &pid, 0, req);
+ if (error == 0 && req->newptr != NULL) {
+ if (pid < 0 || pid > pid_max - 100) /* out of range */
+ pid = pid_max - 100;
+ else if (pid < 2) /* NOP */
+ pid = 0;
+ else if (pid < 100) /* Make it reasonable */
+ pid = 100;
+ randompid = pid;
+ }
+ sx_xunlock(&allproc_lock);
+ return (error);
+}
+
+SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW,
+ 0, 0, sysctl_kern_randompid, "I", "Random PID modulus");
+
+static int
+fork_findpid(int flags)
+{
+ struct proc *p;
+ int trypid;
+ static int pidchecked = 0;
+
+ /*
+ * Requires allproc_lock in order to iterate over the list
+ * of processes, and proctree_lock to access p_pgrp.
+ */
+ sx_assert(&allproc_lock, SX_LOCKED);
+ sx_assert(&proctree_lock, SX_LOCKED);
+
+ /*
+ * Find an unused process ID. We remember a range of unused IDs
+ * ready to use (from lastpid+1 through pidchecked-1).
+ *
+ * If RFHIGHPID is set (used during system boot), do not allocate
+ * low-numbered pids.
+ */
+ trypid = lastpid + 1;
+ if (flags & RFHIGHPID) {
+ if (trypid < 10)
+ trypid = 10;
+ } else {
+ if (randompid)
+ trypid += arc4random() % randompid;
+ }
+retry:
+ /*
+ * If the process ID prototype has wrapped around,
+ * restart somewhat above 0, as the low-numbered procs
+ * tend to include daemons that don't exit.
+ */
+ if (trypid >= pid_max) {
+ trypid = trypid % pid_max;
+ if (trypid < 100)
+ trypid += 100;
+ pidchecked = 0;
+ }
+ if (trypid >= pidchecked) {
+ int doingzomb = 0;
+
+ pidchecked = PID_MAX;
+ /*
+ * Scan the active and zombie procs to check whether this pid
+ * is in use. Remember the lowest pid that's greater
+ * than trypid, so we can avoid checking for a while.
+ */
+ p = LIST_FIRST(&allproc);
+again:
+ for (; p != NULL; p = LIST_NEXT(p, p_list)) {
+ while (p->p_pid == trypid ||
+ (p->p_pgrp != NULL &&
+ (p->p_pgrp->pg_id == trypid ||
+ (p->p_session != NULL &&
+ p->p_session->s_sid == trypid)))) {
+ trypid++;
+ if (trypid >= pidchecked)
+ goto retry;
+ }
+ if (p->p_pid > trypid && pidchecked > p->p_pid)
+ pidchecked = p->p_pid;
+ if (p->p_pgrp != NULL) {
+ if (p->p_pgrp->pg_id > trypid &&
+ pidchecked > p->p_pgrp->pg_id)
+ pidchecked = p->p_pgrp->pg_id;
+ if (p->p_session != NULL &&
+ p->p_session->s_sid > trypid &&
+ pidchecked > p->p_session->s_sid)
+ pidchecked = p->p_session->s_sid;
+ }
+ }
+ if (!doingzomb) {
+ doingzomb = 1;
+ p = LIST_FIRST(&zombproc);
+ goto again;
+ }
+ }
+
+ /*
+ * RFHIGHPID does not mess with the lastpid counter during boot.
+ */
+ if (flags & RFHIGHPID)
+ pidchecked = 0;
+ else
+ lastpid = trypid;
+
+ return (trypid);
+}
+
+static int
+fork_norfproc(struct thread *td, int flags)
+{
+ int error;
+ struct proc *p1;
+
+ KASSERT((flags & RFPROC) == 0,
+ ("fork_norfproc called with RFPROC set"));
+ p1 = td->td_proc;
+
+ if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
+ (flags & (RFCFDG | RFFDG))) {
+ PROC_LOCK(p1);
+ if (thread_single(SINGLE_BOUNDARY)) {
+ PROC_UNLOCK(p1);
+ return (ERESTART);
+ }
+ PROC_UNLOCK(p1);
+ }
+
+ error = vm_forkproc(td, NULL, NULL, NULL, flags);
+ if (error)
+ goto fail;
+
+ /*
+ * Close all file descriptors.
+ */
+ if (flags & RFCFDG) {
+ struct filedesc *fdtmp;
+ fdtmp = fdinit(td->td_proc->p_fd);
+ fdescfree(td);
+ p1->p_fd = fdtmp;
+ }
+
+ /*
+ * Unshare file descriptors (from parent).
+ */
+ if (flags & RFFDG)
+ fdunshare(p1, td);
+
+fail:
+ if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
+ (flags & (RFCFDG | RFFDG))) {
+ PROC_LOCK(p1);
+ thread_single_end();
+ PROC_UNLOCK(p1);
+ }
+ return (error);
+}
+
+static void
+do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2,
+ struct vmspace *vm2, int pdflags)
+{
+ struct proc *p1, *pptr;
+ int p2_held, trypid;
+ struct filedesc *fd;
+ struct filedesc_to_leader *fdtol;
+ struct sigacts *newsigacts;
+
+ sx_assert(&proctree_lock, SX_SLOCKED);
+ sx_assert(&allproc_lock, SX_XLOCKED);
+
+ p2_held = 0;
+ p1 = td->td_proc;
+
+ /*
+ * Increment the nprocs resource before blocking can occur. There
+ * are hard-limits as to the number of processes that can run.
+ */
+ nprocs++;
+
+ trypid = fork_findpid(flags);
+
+ sx_sunlock(&proctree_lock);
+
+ p2->p_state = PRS_NEW; /* protect against others */
+ p2->p_pid = trypid;
+ AUDIT_ARG_PID(p2->p_pid);
+ LIST_INSERT_HEAD(&allproc, p2, p_list);
+ LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
+ tidhash_add(td2);
+ PROC_LOCK(p2);
+ PROC_LOCK(p1);
+
+ sx_xunlock(&allproc_lock);
+
+ bcopy(&p1->p_startcopy, &p2->p_startcopy,
+ __rangeof(struct proc, p_startcopy, p_endcopy));
+ pargs_hold(p2->p_args);
+ PROC_UNLOCK(p1);
+
+ bzero(&p2->p_startzero,
+ __rangeof(struct proc, p_startzero, p_endzero));
+
+ p2->p_ucred = crhold(td->td_ucred);
+
+ /* Tell the prison that we exist. */
+ prison_proc_hold(p2->p_ucred->cr_prison);
+
+ PROC_UNLOCK(p2);
+
+ /*
+ * Malloc things while we don't hold any locks.
+ */
+ if (flags & RFSIGSHARE)
+ newsigacts = NULL;
+ else
+ newsigacts = sigacts_alloc();
+
+ /*
+ * Copy filedesc.
+ */
+ if (flags & RFCFDG) {
+ fd = fdinit(p1->p_fd);
+ fdtol = NULL;
+ } else if (flags & RFFDG) {
+ fd = fdcopy(p1->p_fd);
+ fdtol = NULL;
+ } else {
+ fd = fdshare(p1->p_fd);
+ if (p1->p_fdtol == NULL)
+ p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL,
+ p1->p_leader);
+ if ((flags & RFTHREAD) != 0) {
+ /*
+ * Shared file descriptor table, and shared
+ * process leaders.
+ */
+ fdtol = p1->p_fdtol;
+ FILEDESC_XLOCK(p1->p_fd);
+ fdtol->fdl_refcount++;
+ 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);
+ thread_unlock(td);
+
+ /*
+ * Duplicate sub-structures as needed.
+ * Increase reference counts on shared objects.
+ */
+ p2->p_flag = P_INMEM;
+ p2->p_swtick = ticks;
+ if (p1->p_flag & P_PROFIL)
+ startprofclock(p2);
+ td2->td_ucred = crhold(p2->p_ucred);
+
+ if (flags & RFSIGSHARE) {
+ p2->p_sigacts = sigacts_hold(p1->p_sigacts);
+ } else {
+ sigacts_copy(newsigacts, p1->p_sigacts);
+ p2->p_sigacts = newsigacts;
+ }
+
+ if (flags & RFTSIGZMB)
+ p2->p_sigparent = RFTSIGNUM(flags);
+ else if (flags & RFLINUXTHPN)
+ p2->p_sigparent = SIGUSR1;
+ else
+ p2->p_sigparent = SIGCHLD;
+
+ p2->p_textvp = p1->p_textvp;
+ p2->p_fd = fd;
+ p2->p_fdtol = fdtol;
+
+ /*
+ * p_limit is copy-on-write. Bump its refcount.
+ */
+ lim_fork(p1, p2);
+
+ pstats_fork(p1->p_stats, p2->p_stats);
+
+ PROC_UNLOCK(p1);
+ PROC_UNLOCK(p2);
+
+ /* Bump references to the text vnode (for procfs). */
+ if (p2->p_textvp)
+ vref(p2->p_textvp);
+
+ /*
+ * Set up linkage for kernel based threading.
+ */
+ if ((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;
+ 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 (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);
+
+ /*
+ * If PF_FORK is set, the child process inherits the
+ * procfs ioctl flags from its parent.
+ */
+ if (p1->p_pfsflags & PF_FORK) {
+ p2->p_stops = p1->p_stops;
+ p2->p_pfsflags = p1->p_pfsflags;
+ }
+
+ /*
+ * 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 (flags & RFNOWAIT)
+ pptr = initproc;
+ else
+ pptr = p1;
+ p2->p_pptr = pptr;
+ LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
+ 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, flags);
+
+ if (flags == (RFFDG | RFPROC)) {
+ PCPU_INC(cnt.v_forks);
+ PCPU_ADD(cnt.v_forkpages, p2->p_vmspace->vm_dsize +
+ p2->p_vmspace->vm_ssize);
+ } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
+ PCPU_INC(cnt.v_vforks);
+ PCPU_ADD(cnt.v_vforkpages, p2->p_vmspace->vm_dsize +
+ p2->p_vmspace->vm_ssize);
+ } else if (p1 == &proc0) {
+ PCPU_INC(cnt.v_kthreads);
+ PCPU_ADD(cnt.v_kthreadpages, p2->p_vmspace->vm_dsize +
+ p2->p_vmspace->vm_ssize);
+ } else {
+ PCPU_INC(cnt.v_rforks);
+ PCPU_ADD(cnt.v_rforkpages, p2->p_vmspace->vm_dsize +
+ p2->p_vmspace->vm_ssize);
+ }
+
+#ifdef PROCDESC
+ /*
+ * 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 (flags & RFPROCDESC)
+ procdesc_new(p2, pdflags);
+#endif
+
+ /*
+ * Both processes are set up, now check if any loadable modules want
+ * to adjust anything.
+ */
+ EVENTHANDLER_INVOKE(process_fork, p1, p2, 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
+ * if it has registered an interest. We have to do this only after
+ * p_state is PRS_NORMAL since the fasttrap module will use pfind()
+ * later on.
+ */
+ if (dtrace_fasttrap_fork)
+ dtrace_fasttrap_fork(p1, p2);
+#endif
+ if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED |
+ P_FOLLOWFORK)) {
+ /*
+ * 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;
+ _PHOLD(p2);
+ p2_held = 1;
+ }
+ if (flags & RFPPWAIT) {
+ td->td_pflags |= TDP_RFPPWAIT;
+ td->td_rfppwait_p = p2;
+ }
+ PROC_UNLOCK(p2);
+ if ((flags & RFSTOPPED) == 0) {
+ /*
+ * 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);
+ thread_unlock(td2);
+ }
+
+ /*
+ * Now can be swapped.
+ */
+ _PRELE(p1);
+ PROC_UNLOCK(p1);
+
+ /*
+ * Tell any interested parties about the new process.
+ */
+ knote_fork(&p1->p_klist, p2->p_pid);
+ SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0);
+
+ /*
+ * Wait until debugger is attached to child.
+ */
+ PROC_LOCK(p2);
+ while ((td2->td_dbgflags & TDB_STOPATFORK) != 0)
+ cv_wait(&p2->p_dbgwait, &p2->p_mtx);
+ if (p2_held)
+ _PRELE(p2);
+ PROC_UNLOCK(p2);
+}
+
+int
+fork1(struct thread *td, int flags, int pages, struct proc **procp,
+ int *procdescp, int pdflags)
+{
+ struct proc *p1;
+ struct proc *newproc;
+ int ok;
+ struct thread *td2;
+ struct vmspace *vm2;
+ vm_ooffset_t mem_charged;
+ int error;
+ static int curfail;
+ static struct timeval lastfail;
+#ifdef PROCDESC
+ struct file *fp_procdesc = NULL;
+#endif
+
+ /* 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);
+
+#ifdef PROCDESC
+ 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 (procdescp == NULL)
+ return (EINVAL);
+ }
+#endif
+
+ 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) {
+ *procp = NULL;
+ return (fork_norfproc(td, flags));
+ }
+
+#ifdef PROCDESC
+ /*
+ * 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 = falloc(td, &fp_procdesc, procdescp, 0);
+ if (error != 0)
+ return (error);
+ }
+#endif
+
+ mem_charged = 0;
+ vm2 = NULL;
+ 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 fail1;
+ }
+ proc_linkup(newproc, td2);
+ } else {
+ 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 fail1;
+ }
+ }
+ }
+
+ if ((flags & RFMEM) == 0) {
+ vm2 = vmspace_fork(p1->p_vmspace, &mem_charged);
+ if (vm2 == NULL) {
+ error = ENOMEM;
+ goto fail1;
+ }
+ if (!swap_reserve(mem_charged)) {
+ /*
+ * The swap reservation failed. The accounting
+ * from the entries of the copied vm2 will be
+ * substracted in vmspace_free(), so force the
+ * reservation there.
+ */
+ swap_reserve_force(mem_charged);
+ error = ENOMEM;
+ goto fail1;
+ }
+ } else
+ vm2 = NULL;
+
+ /*
+ * XXX: This is ugly; when we copy resource usage, we need to bump
+ * per-cred resource counters.
+ */
+ newproc->p_ucred = p1->p_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
+ knlist_init_mtx(&newproc->p_klist, &newproc->p_mtx);
+ STAILQ_INIT(&newproc->p_ktr);
+
+ /* We have to lock the process tree while we look for a pid. */
+ sx_slock(&proctree_lock);
+
+ /*
+ * Although process entries are dynamically created, we still keep
+ * a global limit on the maximum number we will create. Don't allow
+ * a nonprivileged user to use the last ten processes; don't let root
+ * exceed the limit. The variable nprocs is the current number of
+ * processes, maxproc is the limit.
+ */
+ sx_xlock(&allproc_lock);
+ if ((nprocs >= maxproc - 10 && priv_check_cred(td->td_ucred,
+ PRIV_MAXPROC, 0) != 0) || nprocs >= maxproc) {
+ error = EAGAIN;
+ goto fail;
+ }
+
+ /*
+ * Increment the count of procs running with this uid. Don't allow
+ * a nonprivileged user to exceed their current limit.
+ *
+ * XXXRW: Can we avoid privilege here if it's not needed?
+ */
+ error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0);
+ if (error == 0)
+ ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0);
+ else {
+ PROC_LOCK(p1);
+ ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1,
+ lim_cur(p1, RLIMIT_NPROC));
+ PROC_UNLOCK(p1);
+ }
+ if (ok) {
+ do_fork(td, flags, newproc, td2, vm2, pdflags);
+
+ /*
+ * Return child proc pointer to parent.
+ */
+ *procp = newproc;
+#ifdef PROCDESC
+ if (flags & RFPROCDESC) {
+ procdesc_finit(newproc->p_procdesc, fp_procdesc);
+ fdrop(fp_procdesc, td);
+ }
+#endif
+ racct_proc_fork_done(newproc);
+ return (0);
+ }
+
+ error = EAGAIN;
+fail:
+ sx_sunlock(&proctree_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);
+#ifdef MAC
+ mac_proc_destroy(newproc);
+#endif
+ racct_proc_exit(newproc);
+fail1:
+ if (vm2 != NULL)
+ vmspace_free(vm2);
+ uma_zfree(proc_zone, newproc);
+#ifdef PROCDESC
+ if ((flags & RFPROCDESC) != 0 && fp_procdesc != NULL) {
+ fdclose(td->td_proc->p_fd, fp_procdesc, *procdescp, td);
+ fdrop(fp_procdesc, td);
+ }
+#endif
+ 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;
+
+ 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->td_sched, 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_set_fork_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_KTHREAD) {
+ printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n",
+ td->td_name, p->p_pid);
+ kproc_exit(0);
+ }
+ 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. Giant is not held on entry, and must not
+ * be held on return. 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, *dbg;
+
+ if (td->td_dbgflags & TDB_STOPATFORK) {
+ p = td->td_proc;
+ sx_xlock(&proctree_lock);
+ PROC_LOCK(p);
+ if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) ==
+ (P_TRACED | P_FOLLOWFORK)) {
+ /*
+ * If debugger still wants auto-attach for the
+ * parent's children, do it now.
+ */
+ dbg = p->p_pptr->p_pptr;
+ p->p_flag |= P_TRACED;
+ p->p_oppid = p->p_pptr->p_pid;
+ proc_reparent(p, dbg);
+ sx_xunlock(&proctree_lock);
+ td->td_dbgflags |= TDB_CHILD;
+ ptracestop(td, SIGSTOP);
+ td->td_dbgflags &= ~TDB_CHILD;
+ } else {
+ /*
+ * ... otherwise clear the request.
+ */
+ sx_xunlock(&proctree_lock);
+ td->td_dbgflags &= ~TDB_STOPATFORK;
+ cv_broadcast(&p->p_dbgwait);
+ }
+ PROC_UNLOCK(p);
+ }
+
+ userret(td, frame);
+
+#ifdef KTRACE
+ if (KTRPOINT(td, KTR_SYSRET))
+ ktrsysret(SYS_fork, 0, 0);
+#endif
+}
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