From 15582d36a15978355d2168eaa018a3736db7281f Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Mon, 13 Oct 2008 10:41:03 +0100 Subject: [PATCH] pty: If the administrator creates a device for a ptmx slave we should not error The open path for ptmx slaves is via the ptmx device. Opening them any other way is not allowed. Vegard Nossum found that previously this was not the case and mknod foo c 128 42; cat foo would produce nasty diagnostics Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- drivers/char/tty_io.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index f40298e9873..2e96ce0fddc 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -1227,7 +1227,8 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p) * init_dev - initialise a tty device * @driver: tty driver we are opening a device on * @idx: device index - * @tty: returned tty structure + * @ret_tty: returned tty structure + * @first_ok: ok to open a new device (used by ptmx) * * Prepare a tty device. This may not be a "new" clean device but * could also be an active device. The pty drivers require special @@ -1248,7 +1249,7 @@ static void tty_line_name(struct tty_driver *driver, int index, char *p) */ static int init_dev(struct tty_driver *driver, int idx, - struct tty_struct **ret_tty) + struct tty_struct **ret_tty, int first_ok) { struct tty_struct *tty, *o_tty; struct ktermios *tp, **tp_loc, *o_tp, **o_tp_loc; @@ -1279,6 +1280,11 @@ static int init_dev(struct tty_driver *driver, int idx, } if (tty) goto fast_track; + if (driver->subtype == PTY_TYPE_MASTER && + (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) { + retval = -EIO; + goto end_init; + } /* * First time open is complex, especially for PTY devices. * This code guarantees that either everything succeeds and the @@ -1413,7 +1419,7 @@ static int init_dev(struct tty_driver *driver, int idx, if (retval) goto release_mem_out; - goto success; + goto success; /* * This fast open can be used if the tty is already open. @@ -1795,7 +1801,7 @@ static void release_dev(struct file *filp) } /** - * tty_open - open a tty device + * __tty_open - open a tty device * @inode: inode of device file * @filp: file pointer to tty * @@ -1874,7 +1880,7 @@ retry_open: return -ENODEV; } got_driver: - retval = init_dev(driver, index, &tty); + retval = init_dev(driver, index, &tty, 0); mutex_unlock(&tty_mutex); if (retval) return retval; @@ -1971,7 +1977,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp) return index; mutex_lock(&tty_mutex); - retval = init_dev(ptm_driver, index, &tty); + retval = init_dev(ptm_driver, index, &tty, 1); mutex_unlock(&tty_mutex); if (retval) -- 2.41.1