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Make TIOCCONS use priv_check() instead of checking /dev/console permissions.

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As discussed with Robert on IRC, checking the permissions on
/dev/console to see if we can call TIOCCONS could be unreliable. When we
run a chroot() without a devfs instance mounted inside, it won't
actually check the permissions on the device node inside the devfs
instance.

Using the already existing PRIV_TTY_CONSOLE for this seems like a better
idea.

Approved by:	rwatson
This commit is contained in:
Ed Schouten 2008-09-06 14:43:32 +00:00
parent 3aa648965f
commit 3c8574bc8a
1 changed files with 8 additions and 35 deletions
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43
sys/kern/tty.c
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@ -44,7 +44,6 @@ __FBSDID("$FreeBSD$");
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/poll.h>
#include <sys/priv.h>
#include <sys/proc.h>
@ -60,7 +59,6 @@ __FBSDID("$FreeBSD$");
#include <sys/ttydefaults.h>
#undef TTYDEFCHARS
#include <sys/ucred.h>
#include <sys/vnode.h>
#include <machine/stdarg.h>
@ -1513,46 +1511,21 @@ tty_generic_ioctl(struct tty *tp, u_long cmd, void *data, struct thread *td)
case TIOCCONS:
/* Set terminal as console TTY. */
if (*(int *)data) {
struct nameidata nd;
int vfslocked;
error = priv_check(td, PRIV_TTY_CONSOLE);
if (error)
return (error);
/*
* XXX: TTY won't slip away, but constty would
* really need to be locked!
* XXX: constty should really need to be locked!
* XXX: allow disconnected constty's to be stolen!
*/
tty_unlock(tp);
if (constty == tp) {
tty_lock(tp);
if (constty == tp)
return (0);
}
if (constty != NULL) {
tty_lock(tp);
if (constty != NULL)
return (EBUSY);
}
/* XXX: allow disconnected constty's to be stolen! */
/*
* Only allow this to work when the user can
* open /dev/console.
*/
NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF|MPSAFE,
UIO_SYSSPACE, "/dev/console", td);
if ((error = namei(&nd)) != 0) {
tty_lock(tp);
return (error);
}
vfslocked = NDHASGIANT(&nd);
NDFREE(&nd, NDF_ONLY_PNBUF);
error = VOP_ACCESS(nd.ni_vp, VREAD, td->td_ucred, td);
vput(nd.ni_vp);
VFS_UNLOCK_GIANT(vfslocked);
if (error) {
tty_lock(tp);
return (error);
}
tty_unlock(tp);
constty_set(tp);
tty_lock(tp);
} else if (constty == tp) {