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FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/kern/sys_procdesc.c |
/*-
* Copyright (c) 2009 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.
*
* 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:
*
* - How to handle ptrace(2)?
* - Will we want to add a pidtoprocdesc(2) system call to allow process
* descriptors to be created for processes without pfork(2)?
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/sys_procdesc.c 225617 2011-09-16 13:58:51Z kmacy $");
#include "opt_procdesc.h"
#include <sys/param.h>
#include <sys/capability.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/procdesc.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>
#include <sys/sysproto.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/ucred.h>
#include <security/audit/audit.h>
#include <vm/uma.h>
#ifdef PROCDESC
FEATURE(process_descriptors, "Process Descriptors");
static uma_zone_t procdesc_zone;
static fo_rdwr_t procdesc_read;
static fo_rdwr_t procdesc_write;
static fo_truncate_t procdesc_truncate;
static fo_ioctl_t procdesc_ioctl;
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_chmod_t procdesc_chmod;
static fo_chown_t procdesc_chown;
static struct fileops procdesc_ops = {
.fo_read = procdesc_read,
.fo_write = procdesc_write,
.fo_truncate = procdesc_truncate,
.fo_ioctl = procdesc_ioctl,
.fo_poll = procdesc_poll,
.fo_kqfilter = procdesc_kqfilter,
.fo_stat = procdesc_stat,
.fo_close = procdesc_close,
.fo_chmod = procdesc_chmod,
.fo_chown = procdesc_chown,
.fo_flags = DFLAG_PASSABLE,
};
/*
* Initialize with VFS so that process descriptors are available along with
* other file descriptor types. As long as it runs before init(8) starts,
* there shouldn't be a problem.
*/
static void
procdesc_init(void *dummy __unused)
{
procdesc_zone = uma_zcreate("procdesc", sizeof(struct procdesc),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
if (procdesc_zone == NULL)
panic("procdesc_init: procdesc_zone not initialized");
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_ANY, procdesc_init, NULL);
/*
* 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 rights,
struct proc **p)
{
struct procdesc *pd;
struct file *fp;
int error;
error = fget(td, fd, rights, &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 rights, pid_t *pidp)
{
struct file *fp;
int error;
error = fget(td, fd, rights, &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, &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 = uma_zalloc(procdesc_zone, 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);
/*
* 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);
}
/*
* 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"));
PROCDESC_LOCK_DESTROY(pd);
uma_zfree(procdesc_zone, pd);
}
}
/*
* 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 == initproc,
("procdesc_exit: closed && parent not init"));
pd->pd_flags |= PDF_EXITED;
/*
* 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);
}
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;
procdesc_free(pd);
}
/*
* procdesc_close() - last close on a process descriptor. If the process is
* still running, terminate with SIGKILL (unless PD_DAEMON is set) and let
* init(8) 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;
PROC_LOCK(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_SLOCK(p);
proc_reap(curthread, p, NULL, 0, NULL);
} 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 init(8) so that there's someone to
* pick up the pieces; finally, terminate with prejudice.
*/
p->p_sigparent = SIGCHLD;
proc_reparent(p, initproc);
if ((pd->pd_flags & PD_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_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
return (EOPNOTSUPP);
}
static int
procdesc_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
int flags, struct thread *td)
{
return (EOPNOTSUPP);
}
static int
procdesc_truncate(struct file *fp, off_t length, struct ucred *active_cred,
struct thread *td)
{
return (EOPNOTSUPP);
}
static int
procdesc_ioctl(struct file *fp, u_long com, void *data,
struct ucred *active_cred, struct thread *td)
{
return (EOPNOTSUPP);
}
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 int
procdesc_kqfilter(struct file *fp, struct knote *kn)
{
return (EOPNOTSUPP);
}
static int
procdesc_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
struct thread *td)
{
struct procdesc *pd;
struct timeval pstart;
/*
* 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);
/* Set birth and [acm] times to process start time. */
pstart = pd->pd_proc->p_stats->p_start;
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_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
struct thread *td)
{
return (EOPNOTSUPP);
}
static int
procdesc_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
struct thread *td)
{
return (EOPNOTSUPP);
}
#else /* !PROCDESC */
int
sys_pdgetpid(struct thread *td, struct pdgetpid_args *uap)
{
return (ENOSYS);
}
#endif /* PROCDESC */