/*- * 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 __FBSDID("$FreeBSD$"); #include "opt_ktrace.h" #include "opt_kstack_pages.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KDTRACE_HOOKS #include dtrace_fork_func_t dtrace_fasttrap_fork; #endif SDT_PROVIDER_DECLARE(proc); SDT_PROBE_DEFINE3(proc, kernel, , 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; { 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); } /* 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. * * Avoid reuse of the process group id, session id or * the reaper subtree id. Note that for process group * and sessions, the amount of reserved pids is * limited by process limit. For the subtree ids, the * id is kept reserved only while there is a * non-reaped process in the subtree, so amount of * reserved pids is limited by process limit times * two. */ p = LIST_FIRST(&allproc); again: for (; p != NULL; p = LIST_NEXT(p, p_list)) { while (p->p_pid == trypid || p->p_reapsubtree == 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(p1, 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, false); fdescfree(td); p1->p_fd = fdtmp; } /* * Unshare file descriptors (from parent). */ if (flags & RFFDG) fdunshare(td); fail: if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) && (flags & (RFCFDG | RFFDG))) { PROC_LOCK(p1); thread_single_end(p1, SINGLE_BOUNDARY); 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); allproc_gen++; 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)); /* 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, false); 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_flag2 = p1->p_flag2 & (P2_NOTRACE | P2_NOTRACE_EXEC); 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; 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); 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) != 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; 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) p2->p_reapsubtree = 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, 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); } /* * 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); /* * 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 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 ((flags & RFMEM) == 0 && 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; struct file *fp_procdesc = 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 (procdescp == NULL) 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) { *procp = NULL; return (fork_norfproc(td, flags)); } /* * 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); } 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 fail2; } 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 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 * substracted 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, crhold(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 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; if (flags & RFPROCDESC) { procdesc_finit(newproc->p_procdesc, fp_procdesc); fdrop(fp_procdesc, td); } 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: crfree(newproc->p_ucred); newproc->p_ucred = NULL; fail2: if (vm2 != NULL) vmspace_free(vm2); uma_zfree(proc_zone, newproc); if ((flags & RFPROCDESC) != 0 && fp_procdesc != NULL) { fdclose(td, fp_procdesc, *procdescp); fdrop(fp_procdesc, td); } 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; CTR2(KTR_PTRACE, "fork_return: attaching to new child pid %d: oppid %d", p->p_pid, p->p_oppid); 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 }