freebsd-dev/sys/kern/sys_procdesc.c
Kip Macy 8451d0dd78 In order to maximize the re-usability of kernel code in user space this
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.

Reviewed by:	rwatson
Approved by:	re (bz)
2011-09-16 13:58:51 +00:00

525 lines
13 KiB
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("$FreeBSD$");
#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 */