freebsd-dev/sys/kern/tty_pty.c
Robert Watson d26dd2d99e When devfs cloning takes place, provide access to the credential of the
process that caused the clone event to take place for the device driver
creating the device.  This allows cloned device drivers to adapt the
device node based on security aspects of the process, such as the uid,
gid, and MAC label.

- Add a cred reference to struct cdev, so that when a device node is
  instantiated as a vnode, the cloning credential can be exposed to
  MAC.

- Add make_dev_cred(), a version of make_dev() that additionally
  accepts the credential to stick in the struct cdev.  Implement it and
  make_dev() in terms of a back-end make_dev_credv().

- Add a new event handler, dev_clone_cred, which can be registered to
  receive the credential instead of dev_clone, if desired.

- Modify the MAC entry point mac_create_devfs_device() to accept an
  optional credential pointer (may be NULL), so that MAC policies can
  inspect and act on the label or other elements of the credential
  when initializing the skeleton device protections.

- Modify tty_pty.c to register clone_dev_cred and invoke make_dev_cred(),
  so that the pty clone credential is exposed to the MAC Framework.

While currently primarily focussed on MAC policies, this change is also
a prerequisite for changes to allow ptys to be instantiated with the UID
of the process looking up the pty.  This requires further changes to the
pty driver -- in particular, to immediately recycle pty nodes on last
close so that the credential-related state can be recreated on next
lookup.

Submitted by:	Andrew Reisse <andrew.reisse@sparta.com>
Obtained from:	TrustedBSD Project
Sponsored by:	SPAWAR, SPARTA
MFC after:	1 week
MFC note:	Merge to 6.x, but not 5.x for ABI reasons
2005-07-14 10:22:09 +00:00

727 lines
17 KiB
C

/*-
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
*
* @(#)tty_pty.c 8.4 (Berkeley) 2/20/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* Pseudo-teletype Driver
* (Actually two drivers, requiring two entries in 'cdevsw')
*/
#include "opt_compat.h"
#include "opt_tty.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#ifndef BURN_BRIDGES
#if defined(COMPAT_43)
#include <sys/ioctl_compat.h>
#endif
#endif
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/poll.h>
#include <sys/kernel.h>
#include <sys/uio.h>
#include <sys/signalvar.h>
#include <sys/malloc.h>
static MALLOC_DEFINE(M_PTY, "ptys", "pty data structures");
static void ptsstart(struct tty *tp);
static void ptsstop(struct tty *tp, int rw);
static void ptcwakeup(struct tty *tp, int flag);
static struct cdev *ptyinit(struct cdev *cdev, struct thread *td);
static d_open_t ptsopen;
static d_close_t ptsclose;
static d_read_t ptsread;
static d_write_t ptswrite;
static d_ioctl_t ptsioctl;
static d_open_t ptcopen;
static d_close_t ptcclose;
static d_read_t ptcread;
static d_ioctl_t ptcioctl;
static d_write_t ptcwrite;
static d_poll_t ptcpoll;
static struct cdevsw pts_cdevsw = {
.d_version = D_VERSION,
.d_open = ptsopen,
.d_close = ptsclose,
.d_read = ptsread,
.d_write = ptswrite,
.d_ioctl = ptsioctl,
.d_name = "pts",
.d_flags = D_TTY | D_NEEDGIANT,
};
static struct cdevsw ptc_cdevsw = {
.d_version = D_VERSION,
.d_open = ptcopen,
.d_close = ptcclose,
.d_read = ptcread,
.d_write = ptcwrite,
.d_ioctl = ptcioctl,
.d_poll = ptcpoll,
.d_name = "ptc",
.d_flags = D_TTY | D_NEEDGIANT,
};
#define BUFSIZ 100 /* Chunk size iomoved to/from user */
struct ptsc {
int pt_flags;
struct selinfo pt_selr, pt_selw;
u_char pt_send;
u_char pt_ucntl;
struct tty *pt_tty;
struct cdev *devs, *devc;
struct prison *pt_prison;
};
#define PF_PKT 0x08 /* packet mode */
#define PF_STOPPED 0x10 /* user told stopped */
#define PF_NOSTOP 0x40
#define PF_UCNTL 0x80 /* user control mode */
#define TSA_PTC_READ(tp) ((void *)&(tp)->t_outq.c_cf)
#define TSA_PTC_WRITE(tp) ((void *)&(tp)->t_rawq.c_cl)
#define TSA_PTS_READ(tp) ((void *)&(tp)->t_canq)
static char *names = "pqrsPQRS";
/*
* This function creates and initializes a pts/ptc pair
*
* pts == /dev/tty[pqrsPQRS][0123456789abcdefghijklmnopqrstuv]
* ptc == /dev/pty[pqrsPQRS][0123456789abcdefghijklmnopqrstuv]
*
* XXX: define and add mapping of upper minor bits to allow more
* than 256 ptys.
*/
static struct cdev *
ptyinit(struct cdev *devc, struct thread *td)
{
struct cdev *devs;
struct ptsc *pt;
int n;
n = minor(devc);
/* For now we only map the lower 8 bits of the minor */
if (n & ~0xff)
return (NULL);
devc->si_flags &= ~SI_CHEAPCLONE;
pt = malloc(sizeof(*pt), M_PTY, M_WAITOK | M_ZERO);
pt->devs = devs = make_dev_cred(&pts_cdevsw, n, td->td_ucred,
UID_ROOT, GID_WHEEL, 0666, "tty%c%r", names[n / 32], n % 32);
pt->devc = devc;
pt->pt_tty = ttymalloc(pt->pt_tty);
pt->pt_tty->t_sc = pt;
devs->si_drv1 = devc->si_drv1 = pt;
devs->si_tty = devc->si_tty = pt->pt_tty;
pt->pt_tty->t_dev = devs;
return (devc);
}
/*ARGSUSED*/
static int
ptsopen(struct cdev *dev, int flag, int devtype, struct thread *td)
{
struct tty *tp;
int error;
struct ptsc *pt;
if (!dev->si_drv1)
return(ENXIO);
pt = dev->si_drv1;
tp = dev->si_tty;
if ((tp->t_state & TS_ISOPEN) == 0) {
ttyinitmode(tp, 1, 0);
} else if (tp->t_state & TS_XCLUDE && suser(td))
return (EBUSY);
else if (pt->pt_prison != td->td_ucred->cr_prison)
return (EBUSY);
if (tp->t_oproc) /* Ctrlr still around. */
(void)ttyld_modem(tp, 1);
while ((tp->t_state & TS_CARR_ON) == 0) {
if (flag&FNONBLOCK)
break;
error = ttysleep(tp, TSA_CARR_ON(tp), TTIPRI | PCATCH,
"ptsopn", 0);
if (error)
return (error);
}
error = ttyld_open(tp, dev);
if (error == 0)
ptcwakeup(tp, FREAD|FWRITE);
return (error);
}
static int
ptsclose(struct cdev *dev, int flag, int mode, struct thread *td)
{
struct tty *tp;
int err;
tp = dev->si_tty;
err = ttyld_close(tp, flag);
(void) tty_close(tp);
return (err);
}
static int
ptsread(struct cdev *dev, struct uio *uio, int flag)
{
struct tty *tp = dev->si_tty;
int error = 0;
if (tp->t_oproc)
error = ttyld_read(tp, uio, flag);
ptcwakeup(tp, FWRITE);
return (error);
}
/*
* Write to pseudo-tty.
* Wakeups of controlling tty will happen
* indirectly, when tty driver calls ptsstart.
*/
static int
ptswrite(struct cdev *dev, struct uio *uio, int flag)
{
struct tty *tp;
tp = dev->si_tty;
if (tp->t_oproc == 0)
return (EIO);
return (ttyld_write(tp, uio, flag));
}
/*
* Start output on pseudo-tty.
* Wake up process selecting or sleeping for input from controlling tty.
*/
static void
ptsstart(struct tty *tp)
{
struct ptsc *pt = tp->t_sc;
if (tp->t_state & TS_TTSTOP)
return;
if (pt->pt_flags & PF_STOPPED) {
pt->pt_flags &= ~PF_STOPPED;
pt->pt_send = TIOCPKT_START;
}
ptcwakeup(tp, FREAD);
}
static void
ptcwakeup(struct tty *tp, int flag)
{
struct ptsc *pt = tp->t_sc;
if (flag & FREAD) {
selwakeuppri(&pt->pt_selr, TTIPRI);
wakeup(TSA_PTC_READ(tp));
}
if (flag & FWRITE) {
selwakeuppri(&pt->pt_selw, TTOPRI);
wakeup(TSA_PTC_WRITE(tp));
}
}
static int
ptcopen(struct cdev *dev, int flag, int devtype, struct thread *td)
{
struct tty *tp;
struct ptsc *pt;
if (!dev->si_drv1)
ptyinit(dev, td);
if (!dev->si_drv1)
return(ENXIO);
tp = dev->si_tty;
if (tp->t_oproc)
return (EIO);
tp->t_timeout = -1;
tp->t_oproc = ptsstart;
tp->t_stop = ptsstop;
(void)ttyld_modem(tp, 1);
tp->t_lflag &= ~EXTPROC;
pt = dev->si_drv1;
pt->pt_prison = td->td_ucred->cr_prison;
pt->pt_flags = 0;
pt->pt_send = 0;
pt->pt_ucntl = 0;
return (0);
}
static int
ptcclose(struct cdev *dev, int flags, int fmt, struct thread *td)
{
struct tty *tp;
tp = dev->si_tty;
(void)ttyld_modem(tp, 0);
/*
* XXX MDMBUF makes no sense for ptys but would inhibit the above
* l_modem(). CLOCAL makes sense but isn't supported. Special
* l_modem()s that ignore carrier drop make no sense for ptys but
* may be in use because other parts of the line discipline make
* sense for ptys. Recover by doing everything that a normal
* ttymodem() would have done except for sending a SIGHUP.
*/
if (tp->t_state & TS_ISOPEN) {
tp->t_state &= ~(TS_CARR_ON | TS_CONNECTED);
tp->t_state |= TS_ZOMBIE;
ttyflush(tp, FREAD | FWRITE);
}
tp->t_oproc = 0; /* mark closed */
return (0);
}
static int
ptcread(struct cdev *dev, struct uio *uio, int flag)
{
struct tty *tp = dev->si_tty;
struct ptsc *pt = dev->si_drv1;
char buf[BUFSIZ];
int error = 0, cc;
/*
* We want to block until the slave
* is open, and there's something to read;
* but if we lost the slave or we're NBIO,
* then return the appropriate error instead.
*/
for (;;) {
if (tp->t_state&TS_ISOPEN) {
if (pt->pt_flags&PF_PKT && pt->pt_send) {
error = ureadc((int)pt->pt_send, uio);
if (error)
return (error);
if (pt->pt_send & TIOCPKT_IOCTL) {
cc = min(uio->uio_resid,
sizeof(tp->t_termios));
uiomove(&tp->t_termios, cc, uio);
}
pt->pt_send = 0;
return (0);
}
if (pt->pt_flags&PF_UCNTL && pt->pt_ucntl) {
error = ureadc((int)pt->pt_ucntl, uio);
if (error)
return (error);
pt->pt_ucntl = 0;
return (0);
}
if (tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0)
break;
}
if ((tp->t_state & TS_CONNECTED) == 0)
return (0); /* EOF */
if (flag & O_NONBLOCK)
return (EWOULDBLOCK);
error = tsleep(TSA_PTC_READ(tp), TTIPRI | PCATCH, "ptcin", 0);
if (error)
return (error);
}
if (pt->pt_flags & (PF_PKT|PF_UCNTL))
error = ureadc(0, uio);
while (uio->uio_resid > 0 && error == 0) {
cc = q_to_b(&tp->t_outq, buf, min(uio->uio_resid, BUFSIZ));
if (cc <= 0)
break;
error = uiomove(buf, cc, uio);
}
ttwwakeup(tp);
return (error);
}
static void
ptsstop(struct tty *tp, int flush)
{
struct ptsc *pt = tp->t_sc;
int flag;
/* note: FLUSHREAD and FLUSHWRITE already ok */
if (flush == 0) {
flush = TIOCPKT_STOP;
pt->pt_flags |= PF_STOPPED;
} else
pt->pt_flags &= ~PF_STOPPED;
pt->pt_send |= flush;
/* change of perspective */
flag = 0;
if (flush & FREAD)
flag |= FWRITE;
if (flush & FWRITE)
flag |= FREAD;
ptcwakeup(tp, flag);
}
static int
ptcpoll(struct cdev *dev, int events, struct thread *td)
{
struct tty *tp = dev->si_tty;
struct ptsc *pt = dev->si_drv1;
int revents = 0;
int s;
if ((tp->t_state & TS_CONNECTED) == 0)
return (events &
(POLLHUP | POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM));
/*
* Need to block timeouts (ttrstart).
*/
s = spltty();
if (events & (POLLIN | POLLRDNORM))
if ((tp->t_state & TS_ISOPEN) &&
((tp->t_outq.c_cc && (tp->t_state & TS_TTSTOP) == 0) ||
((pt->pt_flags & PF_PKT) && pt->pt_send) ||
((pt->pt_flags & PF_UCNTL) && pt->pt_ucntl)))
revents |= events & (POLLIN | POLLRDNORM);
if (events & (POLLOUT | POLLWRNORM))
if (tp->t_state & TS_ISOPEN &&
(((tp->t_rawq.c_cc + tp->t_canq.c_cc < TTYHOG - 2) ||
(tp->t_canq.c_cc == 0 && (tp->t_lflag & ICANON)))))
revents |= events & (POLLOUT | POLLWRNORM);
if (events & POLLHUP)
if ((tp->t_state & TS_CARR_ON) == 0)
revents |= POLLHUP;
if (revents == 0) {
if (events & (POLLIN | POLLRDNORM))
selrecord(td, &pt->pt_selr);
if (events & (POLLOUT | POLLWRNORM))
selrecord(td, &pt->pt_selw);
}
splx(s);
return (revents);
}
static int
ptcwrite(struct cdev *dev, struct uio *uio, int flag)
{
struct tty *tp = dev->si_tty;
u_char *cp = 0;
int cc = 0;
u_char locbuf[BUFSIZ];
int cnt = 0;
int error = 0;
again:
if ((tp->t_state&TS_ISOPEN) == 0)
goto block;
while (uio->uio_resid > 0 || cc > 0) {
if (cc == 0) {
cc = min(uio->uio_resid, BUFSIZ);
cp = locbuf;
error = uiomove(cp, cc, uio);
if (error)
return (error);
/* check again for safety */
if ((tp->t_state & TS_ISOPEN) == 0) {
/* adjust for data copied in but not written */
uio->uio_resid += cc;
return (EIO);
}
}
while (cc > 0) {
if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 &&
(tp->t_canq.c_cc > 0 || !(tp->t_lflag&ICANON))) {
wakeup(TSA_HUP_OR_INPUT(tp));
goto block;
}
ttyld_rint(tp, *cp++);
cnt++;
cc--;
}
cc = 0;
}
return (0);
block:
/*
* Come here to wait for slave to open, for space
* in outq, or space in rawq, or an empty canq.
*/
if ((tp->t_state & TS_CONNECTED) == 0) {
/* adjust for data copied in but not written */
uio->uio_resid += cc;
return (EIO);
}
if (flag & O_NONBLOCK) {
/* adjust for data copied in but not written */
uio->uio_resid += cc;
if (cnt == 0)
return (EWOULDBLOCK);
return (0);
}
error = tsleep(TSA_PTC_WRITE(tp), TTOPRI | PCATCH, "ptcout", 0);
if (error) {
/* adjust for data copied in but not written */
uio->uio_resid += cc;
return (error);
}
goto again;
}
/*ARGSUSED*/
static int
ptcioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag, struct thread *td)
{
struct tty *tp = dev->si_tty;
struct ptsc *pt = dev->si_drv1;
switch (cmd) {
case TIOCGPGRP:
/*
* We avoid calling ttioctl on the controller since,
* in that case, tp must be the controlling terminal.
*/
*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : 0;
return (0);
case TIOCPKT:
if (*(int *)data) {
if (pt->pt_flags & PF_UCNTL)
return (EINVAL);
pt->pt_flags |= PF_PKT;
} else
pt->pt_flags &= ~PF_PKT;
return (0);
case TIOCUCNTL:
if (*(int *)data) {
if (pt->pt_flags & PF_PKT)
return (EINVAL);
pt->pt_flags |= PF_UCNTL;
} else
pt->pt_flags &= ~PF_UCNTL;
return (0);
}
/*
* The rest of the ioctls shouldn't be called until
* the slave is open.
*/
if ((tp->t_state & TS_ISOPEN) == 0)
return (EAGAIN);
switch (cmd) {
#ifndef BURN_BRIDGES
#ifdef COMPAT_43
case TIOCSETP:
case TIOCSETN:
#endif
#endif
case TIOCSETD:
case TIOCSETA:
case TIOCSETAW:
case TIOCSETAF:
/*
* IF CONTROLLER STTY THEN MUST FLUSH TO PREVENT A HANG.
* ttywflush(tp) will hang if there are characters in
* the outq.
*/
ndflush(&tp->t_outq, tp->t_outq.c_cc);
break;
case TIOCSIG:
if (*(unsigned int *)data >= NSIG ||
*(unsigned int *)data == 0)
return(EINVAL);
if ((tp->t_lflag&NOFLSH) == 0)
ttyflush(tp, FREAD|FWRITE);
if (tp->t_pgrp != NULL) {
PGRP_LOCK(tp->t_pgrp);
pgsignal(tp->t_pgrp, *(unsigned int *)data, 1);
PGRP_UNLOCK(tp->t_pgrp);
}
if ((*(unsigned int *)data == SIGINFO) &&
((tp->t_lflag&NOKERNINFO) == 0))
ttyinfo(tp);
return(0);
}
return (ptsioctl(dev, cmd, data, flag, td));
}
/*ARGSUSED*/
static int
ptsioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag, struct thread *td)
{
struct tty *tp = dev->si_tty;
struct ptsc *pt = dev->si_drv1;
u_char *cc = tp->t_cc;
int stop, error;
if (cmd == TIOCEXT) {
/*
* When the EXTPROC bit is being toggled, we need
* to send an TIOCPKT_IOCTL if the packet driver
* is turned on.
*/
if (*(int *)data) {
if (pt->pt_flags & PF_PKT) {
pt->pt_send |= TIOCPKT_IOCTL;
ptcwakeup(tp, FREAD);
}
tp->t_lflag |= EXTPROC;
} else {
if ((tp->t_lflag & EXTPROC) &&
(pt->pt_flags & PF_PKT)) {
pt->pt_send |= TIOCPKT_IOCTL;
ptcwakeup(tp, FREAD);
}
tp->t_lflag &= ~EXTPROC;
}
return(0);
}
error = ttyioctl(dev, cmd, data, flag, td);
if (error == ENOTTY) {
if (pt->pt_flags & PF_UCNTL &&
(cmd & ~0xff) == UIOCCMD(0)) {
if (cmd & 0xff) {
pt->pt_ucntl = (u_char)cmd;
ptcwakeup(tp, FREAD);
}
return (0);
}
error = ENOTTY;
}
/*
* If external processing and packet mode send ioctl packet.
*/
if ((tp->t_lflag&EXTPROC) && (pt->pt_flags & PF_PKT)) {
switch(cmd) {
case TIOCSETA:
case TIOCSETAW:
case TIOCSETAF:
#ifndef BURN_BRIDGES
#ifdef COMPAT_43
case TIOCSETP:
case TIOCSETN:
case TIOCSETC:
case TIOCSLTC:
case TIOCLBIS:
case TIOCLBIC:
case TIOCLSET:
#endif
#endif
pt->pt_send |= TIOCPKT_IOCTL;
ptcwakeup(tp, FREAD);
break;
default:
break;
}
}
stop = (tp->t_iflag & IXON) && CCEQ(cc[VSTOP], CTRL('s'))
&& CCEQ(cc[VSTART], CTRL('q'));
if (pt->pt_flags & PF_NOSTOP) {
if (stop) {
pt->pt_send &= ~TIOCPKT_NOSTOP;
pt->pt_send |= TIOCPKT_DOSTOP;
pt->pt_flags &= ~PF_NOSTOP;
ptcwakeup(tp, FREAD);
}
} else {
if (!stop) {
pt->pt_send &= ~TIOCPKT_DOSTOP;
pt->pt_send |= TIOCPKT_NOSTOP;
pt->pt_flags |= PF_NOSTOP;
ptcwakeup(tp, FREAD);
}
}
return (error);
}
static void
pty_clone(void *arg, struct ucred *cr, char *name, int namelen,
struct cdev **dev)
{
int u;
if (*dev != NULL)
return;
if (bcmp(name, "pty", 3) != 0)
return;
if (name[5] != '\0')
return;
switch (name[3]) {
case 'p': u = 0; break;
case 'q': u = 32; break;
case 'r': u = 64; break;
case 's': u = 96; break;
case 'P': u = 128; break;
case 'Q': u = 160; break;
case 'R': u = 192; break;
case 'S': u = 224; break;
default: return;
}
if (name[4] >= '0' && name[4] <= '9')
u += name[4] - '0';
else if (name[4] >= 'a' && name[4] <= 'v')
u += name[4] - 'a' + 10;
else
return;
*dev = make_dev_cred(&ptc_cdevsw, u, cr,
UID_ROOT, GID_WHEEL, 0666, "pty%c%r", names[u / 32], u % 32);
dev_ref(*dev);
(*dev)->si_flags |= SI_CHEAPCLONE;
return;
}
static void
ptc_drvinit(void *unused)
{
EVENTHANDLER_REGISTER(dev_clone_cred, pty_clone, 0, 1000);
}
SYSINIT(ptcdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,ptc_drvinit,NULL)