764028016f
Lock cdev mutex too to close the race with tty being freed. Relock clone_drain_lock to prevent the LOR with proctree lock, thus add #include <fs/devfs/devfs_int.h>. Suggested by: tegge Debugging help and testing by: Peter Holm Approved by: re (kensmith)
97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
/*-
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* Copyright (c) 2003 Poul-Henning Kamp. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/sx.h>
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#include <sys/vnode.h>
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#include <fs/devfs/devfs.h>
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#include <fs/devfs/devfs_int.h>
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static d_open_t cttyopen;
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static struct cdevsw ctty_cdevsw = {
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.d_version = D_VERSION,
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.d_open = cttyopen,
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.d_name = "ctty",
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.d_flags = D_TTY | D_NEEDGIANT,
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};
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static struct cdev *ctty;
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static int
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cttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
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{
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return (ENXIO);
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}
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static void
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ctty_clone(void *arg, struct ucred *cred, char *name, int namelen,
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struct cdev **dev)
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{
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if (*dev != NULL)
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return;
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if (strcmp(name, "tty"))
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return;
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sx_sunlock(&clone_drain_lock);
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mtx_lock(&Giant);
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sx_slock(&proctree_lock);
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sx_slock(&clone_drain_lock);
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dev_lock();
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if (!(curthread->td_proc->p_flag & P_CONTROLT))
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*dev = ctty;
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else if (curthread->td_proc->p_session->s_ttyvp == NULL)
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*dev = ctty;
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else if (curthread->td_proc->p_session->s_ttyvp->v_type == VBAD ||
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curthread->td_proc->p_session->s_ttyvp->v_rdev == NULL) {
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/* e.g. s_ttyvp was revoked */
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*dev = ctty;
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} else
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*dev = curthread->td_proc->p_session->s_ttyvp->v_rdev;
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dev_refl(*dev);
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dev_unlock();
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sx_sunlock(&proctree_lock);
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mtx_unlock(&Giant);
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}
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static void
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ctty_drvinit(void *unused)
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{
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EVENTHANDLER_REGISTER(dev_clone, ctty_clone, 0, 1000);
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ctty = make_dev(&ctty_cdevsw, 0, 0, 0, 0666, "ctty");
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}
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SYSINIT(cttydev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ctty_drvinit,NULL)
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