linux/fs/proc/proc_tty.c
Linus Torvalds 6c2754c28f Revert "tty: Add a new file /proc/tty/consoles"
This reverts commit f4a3e0bceb.  Jiri
Sladby points out that the tty structure we're using may already be
gone, and Al Viro doesn't hold back in complaining about the random
loading of 'filp->private_data' which doesn't have to be a pointer at
all, nor does checking the magic field for TTY_MAGIC prove anything.

Belated review by Al:

 "a) global variable depending on stdin of the last opener? Affecting
     output of read(2)? Really?

  b) iterator is broken; list should be locked in ->start(), unlocked in
     ->stop() and *NOT* unlocked/relocked in ->next()

  c) ->show() ought to do nothing in case of ->device == NULL, instead
     of skipping those in ->next()/->start()

  d) regardless of the merits of the bright idea about asterisk at that
     line in output *and* regardless of (a), the implementation is not
     only atrociously ugly, it's actually very likely to be a roothole.
     Verifying that Cthulhu knows what number happens to be address of a
     tty_struct by blindly dereferencing memory at that address...
     Ouch.

  Please revert that crap."

And Christoph pipes in and NAK's the approach of walking fd tables etc
too.  So it's pretty unanimous.

Noticed-by: Jri Slaby <jslaby@suse.cz>
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Werner Fink <werner@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-23 08:14:12 -07:00

189 lines
4.7 KiB
C

/*
* proc_tty.c -- handles /proc/tty
*
* Copyright 1997, Theodore Ts'o
*/
#include <asm/uaccess.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/tty.h>
#include <linux/seq_file.h>
#include <linux/bitops.h>
/*
* The /proc/tty directory inodes...
*/
static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;
/*
* This is the handler for /proc/tty/drivers
*/
static void show_tty_range(struct seq_file *m, struct tty_driver *p,
dev_t from, int num)
{
seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown");
seq_printf(m, "/dev/%-8s ", p->name);
if (p->num > 1) {
seq_printf(m, "%3d %d-%d ", MAJOR(from), MINOR(from),
MINOR(from) + num - 1);
} else {
seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from));
}
switch (p->type) {
case TTY_DRIVER_TYPE_SYSTEM:
seq_printf(m, "system");
if (p->subtype == SYSTEM_TYPE_TTY)
seq_printf(m, ":/dev/tty");
else if (p->subtype == SYSTEM_TYPE_SYSCONS)
seq_printf(m, ":console");
else if (p->subtype == SYSTEM_TYPE_CONSOLE)
seq_printf(m, ":vtmaster");
break;
case TTY_DRIVER_TYPE_CONSOLE:
seq_printf(m, "console");
break;
case TTY_DRIVER_TYPE_SERIAL:
seq_printf(m, "serial");
break;
case TTY_DRIVER_TYPE_PTY:
if (p->subtype == PTY_TYPE_MASTER)
seq_printf(m, "pty:master");
else if (p->subtype == PTY_TYPE_SLAVE)
seq_printf(m, "pty:slave");
else
seq_printf(m, "pty");
break;
default:
seq_printf(m, "type:%d.%d", p->type, p->subtype);
}
seq_putc(m, '\n');
}
static int show_tty_driver(struct seq_file *m, void *v)
{
struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers);
dev_t from = MKDEV(p->major, p->minor_start);
dev_t to = from + p->num;
if (&p->tty_drivers == tty_drivers.next) {
/* pseudo-drivers first */
seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty");
seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0);
seq_printf(m, "system:/dev/tty\n");
seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console");
seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1);
seq_printf(m, "system:console\n");
#ifdef CONFIG_UNIX98_PTYS
seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx");
seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2);
seq_printf(m, "system\n");
#endif
#ifdef CONFIG_VT
seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0");
seq_printf(m, "%3d %7d ", TTY_MAJOR, 0);
seq_printf(m, "system:vtmaster\n");
#endif
}
while (MAJOR(from) < MAJOR(to)) {
dev_t next = MKDEV(MAJOR(from)+1, 0);
show_tty_range(m, p, from, next - from);
from = next;
}
if (from != to)
show_tty_range(m, p, from, to - from);
return 0;
}
/* iterator */
static void *t_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&tty_mutex);
return seq_list_start(&tty_drivers, *pos);
}
static void *t_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &tty_drivers, pos);
}
static void t_stop(struct seq_file *m, void *v)
{
mutex_unlock(&tty_mutex);
}
static const struct seq_operations tty_drivers_op = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = show_tty_driver
};
static int tty_drivers_open(struct inode *inode, struct file *file)
{
return seq_open(file, &tty_drivers_op);
}
static const struct file_operations proc_tty_drivers_operations = {
.open = tty_drivers_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
/*
* This function is called by tty_register_driver() to handle
* registering the driver's /proc handler into /proc/tty/driver/<foo>
*/
void proc_tty_register_driver(struct tty_driver *driver)
{
struct proc_dir_entry *ent;
if (!driver->driver_name || driver->proc_entry ||
!driver->ops->proc_fops)
return;
ent = proc_create_data(driver->driver_name, 0, proc_tty_driver,
driver->ops->proc_fops, driver);
driver->proc_entry = ent;
}
/*
* This function is called by tty_unregister_driver()
*/
void proc_tty_unregister_driver(struct tty_driver *driver)
{
struct proc_dir_entry *ent;
ent = driver->proc_entry;
if (!ent)
return;
remove_proc_entry(driver->driver_name, proc_tty_driver);
driver->proc_entry = NULL;
}
/*
* Called by proc_root_init() to initialize the /proc/tty subtree
*/
void __init proc_tty_init(void)
{
if (!proc_mkdir("tty", NULL))
return;
proc_tty_ldisc = proc_mkdir("tty/ldisc", NULL);
/*
* /proc/tty/driver/serial reveals the exact character counts for
* serial links which is just too easy to abuse for inferring
* password lengths and inter-keystroke timings during password
* entry.
*/
proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR|S_IXUSR, NULL);
proc_create("tty/ldiscs", 0, NULL, &tty_ldiscs_proc_fops);
proc_create("tty/drivers", 0, NULL, &proc_tty_drivers_operations);
}