/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2009, 2016 Robert N. M. Watson * All rights reserved. * * This software was developed at the University of Cambridge Computer * Laboratory with support from a grant from Google, Inc. * * Portions of this software were developed by BAE Systems, the University of * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent * Computing (TC) research program. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. */ /*- * FreeBSD process descriptor facility. * * Some processes are represented by a file descriptor, which will be used in * preference to signaling and pids for the purposes of process management, * and is, in effect, a form of capability. When a process descriptor is * used with a process, it ceases to be visible to certain traditional UNIX * process facilities, such as waitpid(2). * * Some semantics: * * - At most one process descriptor will exist for any process, although * references to that descriptor may be held from many processes (or even * be in flight between processes over a local domain socket). * - Last close on the process descriptor will terminate the process using * SIGKILL and reparent it to init so that there's a process to reap it * when it's done exiting. * - If the process exits before the descriptor is closed, it will not * generate SIGCHLD on termination, or be picked up by waitpid(). * - The pdkill(2) system call may be used to deliver a signal to the process * using its process descriptor. * - The pdwait4(2) system call may be used to block (or not) on a process * descriptor to collect termination information. * * Open questions: * * - Will we want to add a pidtoprocdesc(2) system call to allow process * descriptors to be created for processes without pdfork(2)? */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include FEATURE(process_descriptors, "Process Descriptors"); MALLOC_DEFINE(M_PROCDESC, "procdesc", "process descriptors"); static fo_poll_t procdesc_poll; static fo_kqfilter_t procdesc_kqfilter; static fo_stat_t procdesc_stat; static fo_close_t procdesc_close; static fo_fill_kinfo_t procdesc_fill_kinfo; static struct fileops procdesc_ops = { .fo_read = invfo_rdwr, .fo_write = invfo_rdwr, .fo_truncate = invfo_truncate, .fo_ioctl = invfo_ioctl, .fo_poll = procdesc_poll, .fo_kqfilter = procdesc_kqfilter, .fo_stat = procdesc_stat, .fo_close = procdesc_close, .fo_chmod = invfo_chmod, .fo_chown = invfo_chown, .fo_sendfile = invfo_sendfile, .fo_fill_kinfo = procdesc_fill_kinfo, .fo_flags = DFLAG_PASSABLE, }; /* * Return a locked process given a process descriptor, or ESRCH if it has * died. */ int procdesc_find(struct thread *td, int fd, cap_rights_t *rightsp, struct proc **p) { struct procdesc *pd; struct file *fp; int error; error = fget(td, fd, rightsp, &fp); if (error) return (error); if (fp->f_type != DTYPE_PROCDESC) { error = EBADF; goto out; } pd = fp->f_data; sx_slock(&proctree_lock); if (pd->pd_proc != NULL) { *p = pd->pd_proc; PROC_LOCK(*p); } else error = ESRCH; sx_sunlock(&proctree_lock); out: fdrop(fp, td); return (error); } /* * Function to be used by procstat(1) sysctls when returning procdesc * information. */ pid_t procdesc_pid(struct file *fp_procdesc) { struct procdesc *pd; KASSERT(fp_procdesc->f_type == DTYPE_PROCDESC, ("procdesc_pid: !procdesc")); pd = fp_procdesc->f_data; return (pd->pd_pid); } /* * Retrieve the PID associated with a process descriptor. */ int kern_pdgetpid(struct thread *td, int fd, cap_rights_t *rightsp, pid_t *pidp) { struct file *fp; int error; error = fget(td, fd, rightsp, &fp); if (error) return (error); if (fp->f_type != DTYPE_PROCDESC) { error = EBADF; goto out; } *pidp = procdesc_pid(fp); out: fdrop(fp, td); return (error); } /* * System call to return the pid of a process given its process descriptor. */ int sys_pdgetpid(struct thread *td, struct pdgetpid_args *uap) { pid_t pid; int error; AUDIT_ARG_FD(uap->fd); error = kern_pdgetpid(td, uap->fd, &cap_pdgetpid_rights, &pid); if (error == 0) error = copyout(&pid, uap->pidp, sizeof(pid)); return (error); } /* * When a new process is forked by pdfork(), a file descriptor is allocated * by the fork code first, then the process is forked, and then we get a * chance to set up the process descriptor. Failure is not permitted at this * point, so procdesc_new() must succeed. */ void procdesc_new(struct proc *p, int flags) { struct procdesc *pd; pd = malloc(sizeof(*pd), M_PROCDESC, M_WAITOK | M_ZERO); pd->pd_proc = p; pd->pd_pid = p->p_pid; p->p_procdesc = pd; pd->pd_flags = 0; if (flags & PD_DAEMON) pd->pd_flags |= PDF_DAEMON; PROCDESC_LOCK_INIT(pd); knlist_init_mtx(&pd->pd_selinfo.si_note, &pd->pd_lock); /* * Process descriptors start out with two references: one from their * struct file, and the other from their struct proc. */ refcount_init(&pd->pd_refcount, 2); } /* * Create a new process decriptor for the process that refers to it. */ int procdesc_falloc(struct thread *td, struct file **resultfp, int *resultfd, int flags, struct filecaps *fcaps) { int fflags; fflags = 0; if (flags & PD_CLOEXEC) fflags = O_CLOEXEC; return (falloc_caps(td, resultfp, resultfd, fflags, fcaps)); } /* * Initialize a file with a process descriptor. */ void procdesc_finit(struct procdesc *pdp, struct file *fp) { finit(fp, FREAD | FWRITE, DTYPE_PROCDESC, pdp, &procdesc_ops); } static void procdesc_free(struct procdesc *pd) { /* * When the last reference is released, we assert that the descriptor * has been closed, but not that the process has exited, as we will * detach the descriptor before the process dies if the descript is * closed, as we can't wait synchronously. */ if (refcount_release(&pd->pd_refcount)) { KASSERT(pd->pd_proc == NULL, ("procdesc_free: pd_proc != NULL")); KASSERT((pd->pd_flags & PDF_CLOSED), ("procdesc_free: !PDF_CLOSED")); knlist_destroy(&pd->pd_selinfo.si_note); PROCDESC_LOCK_DESTROY(pd); free(pd, M_PROCDESC); } } /* * procdesc_exit() - notify a process descriptor that its process is exiting. * We use the proctree_lock to ensure that process exit either happens * strictly before or strictly after a concurrent call to procdesc_close(). */ int procdesc_exit(struct proc *p) { struct procdesc *pd; sx_assert(&proctree_lock, SA_XLOCKED); PROC_LOCK_ASSERT(p, MA_OWNED); KASSERT(p->p_procdesc != NULL, ("procdesc_exit: p_procdesc NULL")); pd = p->p_procdesc; PROCDESC_LOCK(pd); KASSERT((pd->pd_flags & PDF_CLOSED) == 0 || p->p_pptr == p->p_reaper, ("procdesc_exit: closed && parent not reaper")); pd->pd_flags |= PDF_EXITED; pd->pd_xstat = KW_EXITCODE(p->p_xexit, p->p_xsig); /* * If the process descriptor has been closed, then we have nothing * to do; return 1 so that init will get SIGCHLD and do the reaping. * Clean up the procdesc now rather than letting it happen during * that reap. */ if (pd->pd_flags & PDF_CLOSED) { PROCDESC_UNLOCK(pd); pd->pd_proc = NULL; p->p_procdesc = NULL; procdesc_free(pd); return (1); } if (pd->pd_flags & PDF_SELECTED) { pd->pd_flags &= ~PDF_SELECTED; selwakeup(&pd->pd_selinfo); } KNOTE_LOCKED(&pd->pd_selinfo.si_note, NOTE_EXIT); PROCDESC_UNLOCK(pd); return (0); } /* * When a process descriptor is reaped, perhaps as a result of close() or * pdwait4(), release the process's reference on the process descriptor. */ void procdesc_reap(struct proc *p) { struct procdesc *pd; sx_assert(&proctree_lock, SA_XLOCKED); KASSERT(p->p_procdesc != NULL, ("procdesc_reap: p_procdesc == NULL")); pd = p->p_procdesc; pd->pd_proc = NULL; p->p_procdesc = NULL; procdesc_free(pd); } /* * procdesc_close() - last close on a process descriptor. If the process is * still running, terminate with SIGKILL (unless PDF_DAEMON is set) and let * its reaper clean up the mess; if not, we have to clean up the zombie * ourselves. */ static int procdesc_close(struct file *fp, struct thread *td) { struct procdesc *pd; struct proc *p; KASSERT(fp->f_type == DTYPE_PROCDESC, ("procdesc_close: !procdesc")); pd = fp->f_data; fp->f_ops = &badfileops; fp->f_data = NULL; sx_xlock(&proctree_lock); PROCDESC_LOCK(pd); pd->pd_flags |= PDF_CLOSED; PROCDESC_UNLOCK(pd); p = pd->pd_proc; if (p == NULL) { /* * This is the case where process' exit status was already * collected and procdesc_reap() was already called. */ sx_xunlock(&proctree_lock); } else { PROC_LOCK(p); AUDIT_ARG_PROCESS(p); if (p->p_state == PRS_ZOMBIE) { /* * If the process is already dead and just awaiting * reaping, do that now. This will release the * process's reference to the process descriptor when it * calls back into procdesc_reap(). */ proc_reap(curthread, p, NULL, 0); } else { /* * If the process is not yet dead, we need to kill it, * but we can't wait around synchronously for it to go * away, as that path leads to madness (and deadlocks). * First, detach the process from its descriptor so that * its exit status will be reported normally. */ pd->pd_proc = NULL; p->p_procdesc = NULL; procdesc_free(pd); /* * Next, reparent it to its reaper (usually init(8)) so * that there's someone to pick up the pieces; finally, * terminate with prejudice. */ p->p_sigparent = SIGCHLD; if ((p->p_flag & P_TRACED) == 0) { proc_reparent(p, p->p_reaper, true); } else { proc_clear_orphan(p); p->p_oppid = p->p_reaper->p_pid; proc_add_orphan(p, p->p_reaper); } if ((pd->pd_flags & PDF_DAEMON) == 0) kern_psignal(p, SIGKILL); PROC_UNLOCK(p); sx_xunlock(&proctree_lock); } } /* * Release the file descriptor's reference on the process descriptor. */ procdesc_free(pd); return (0); } static int procdesc_poll(struct file *fp, int events, struct ucred *active_cred, struct thread *td) { struct procdesc *pd; int revents; revents = 0; pd = fp->f_data; PROCDESC_LOCK(pd); if (pd->pd_flags & PDF_EXITED) revents |= POLLHUP; if (revents == 0) { selrecord(td, &pd->pd_selinfo); pd->pd_flags |= PDF_SELECTED; } PROCDESC_UNLOCK(pd); return (revents); } static void procdesc_kqops_detach(struct knote *kn) { struct procdesc *pd; pd = kn->kn_fp->f_data; knlist_remove(&pd->pd_selinfo.si_note, kn, 0); } static int procdesc_kqops_event(struct knote *kn, long hint) { struct procdesc *pd; u_int event; pd = kn->kn_fp->f_data; if (hint == 0) { /* * Initial test after registration. Generate a NOTE_EXIT in * case the process already terminated before registration. */ event = pd->pd_flags & PDF_EXITED ? NOTE_EXIT : 0; } else { /* Mask off extra data. */ event = (u_int)hint & NOTE_PCTRLMASK; } /* If the user is interested in this event, record it. */ if (kn->kn_sfflags & event) kn->kn_fflags |= event; /* Process is gone, so flag the event as finished. */ if (event == NOTE_EXIT) { kn->kn_flags |= EV_EOF | EV_ONESHOT; if (kn->kn_fflags & NOTE_EXIT) kn->kn_data = pd->pd_xstat; if (kn->kn_fflags == 0) kn->kn_flags |= EV_DROP; return (1); } return (kn->kn_fflags != 0); } static struct filterops procdesc_kqops = { .f_isfd = 1, .f_detach = procdesc_kqops_detach, .f_event = procdesc_kqops_event, }; static int procdesc_kqfilter(struct file *fp, struct knote *kn) { struct procdesc *pd; pd = fp->f_data; switch (kn->kn_filter) { case EVFILT_PROCDESC: kn->kn_fop = &procdesc_kqops; kn->kn_flags |= EV_CLEAR; knlist_add(&pd->pd_selinfo.si_note, kn, 0); return (0); default: return (EINVAL); } } static int procdesc_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, struct thread *td) { struct procdesc *pd; struct timeval pstart, boottime; /* * XXXRW: Perhaps we should cache some more information from the * process so that we can return it reliably here even after it has * died. For example, caching its credential data. */ bzero(sb, sizeof(*sb)); pd = fp->f_data; sx_slock(&proctree_lock); if (pd->pd_proc != NULL) { PROC_LOCK(pd->pd_proc); AUDIT_ARG_PROCESS(pd->pd_proc); /* Set birth and [acm] times to process start time. */ pstart = pd->pd_proc->p_stats->p_start; getboottime(&boottime); timevaladd(&pstart, &boottime); TIMEVAL_TO_TIMESPEC(&pstart, &sb->st_birthtim); sb->st_atim = sb->st_birthtim; sb->st_ctim = sb->st_birthtim; sb->st_mtim = sb->st_birthtim; if (pd->pd_proc->p_state != PRS_ZOMBIE) sb->st_mode = S_IFREG | S_IRWXU; else sb->st_mode = S_IFREG; sb->st_uid = pd->pd_proc->p_ucred->cr_ruid; sb->st_gid = pd->pd_proc->p_ucred->cr_rgid; PROC_UNLOCK(pd->pd_proc); } else sb->st_mode = S_IFREG; sx_sunlock(&proctree_lock); return (0); } static int procdesc_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) { struct procdesc *pdp; kif->kf_type = KF_TYPE_PROCDESC; pdp = fp->f_data; kif->kf_un.kf_proc.kf_pid = pdp->pd_pid; return (0); }