linux/fs/proc/proc_tty.c
Alexey Dobriyan ca509f69de Protect tty drivers list with tty_mutex
Additions and removal from tty_drivers list were just done as well as
iterating on it for /proc/tty/drivers generation.

testing: modprobe/rmmod loop of simple module which does nothing but
tty_register_driver() vs cat /proc/tty/drivers loop

BUG: unable to handle kernel paging request at virtual address 6b6b6b6b
 printing eip:
c01cefa7
*pde = 00000000
Oops: 0000 [#1]
PREEMPT
last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol
Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs
CPU:    0
EIP:    0060:[<c01cefa7>]    Not tainted VLI
EFLAGS: 00010297   (2.6.21-rc4-mm1 #4)
EIP is at vsnprintf+0x3a4/0x5fc
eax: 6b6b6b6b   ebx: f6cb50f2   ecx: 6b6b6b6b   edx: fffffffe
esi: c0354700   edi: f6cb6000   ebp: 6b6b6b6b   esp: f31f5e68
ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000)
Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e
       f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2
       f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc
Call Trace:
 [<c0103f20>] restore_nocheck+0x12/0x15
 [<c013003a>] mark_held_locks+0x6d/0x86
 [<c0103f20>] restore_nocheck+0x12/0x15
 [<c0175416>] seq_printf+0x2e/0x52
 [<c0192895>] show_tty_range+0x35/0x1f3
 [<c0175416>] seq_printf+0x2e/0x52
 [<c0192add>] show_tty_driver+0x8a/0x1d9
 [<c01758f6>] seq_read+0x70/0x2ba
 [<c0175886>] seq_read+0x0/0x2ba
 [<c018d8e6>] proc_reg_read+0x63/0x9f
 [<c015e764>] vfs_read+0x7d/0xb5
 [<c018d883>] proc_reg_read+0x0/0x9f
 [<c015eab1>] sys_read+0x41/0x6a
 [<c0103e4e>] sysenter_past_esp+0x5f/0x99
 =======================
Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89
EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:05 -07:00

246 lines
5.9 KiB
C

/*
* proc_tty.c -- handles /proc/tty
*
* Copyright 1997, Theodore Ts'o
*/
#include <asm/uaccess.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>
static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data);
/*
* 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 = v;
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)
{
struct list_head *p;
loff_t l = *pos;
mutex_lock(&tty_mutex);
list_for_each(p, &tty_drivers)
if (!l--)
return list_entry(p, struct tty_driver, tty_drivers);
return NULL;
}
static void *t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct list_head *p = ((struct tty_driver *)v)->tty_drivers.next;
(*pos)++;
return p==&tty_drivers ? NULL :
list_entry(p, struct tty_driver, tty_drivers);
}
static void t_stop(struct seq_file *m, void *v)
{
mutex_unlock(&tty_mutex);
}
static 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 is the handler for /proc/tty/ldiscs
*/
static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
int i;
int len = 0;
off_t begin = 0;
struct tty_ldisc *ld;
for (i=0; i < NR_LDISCS; i++) {
ld = tty_ldisc_get(i);
if (ld == NULL)
continue;
len += sprintf(page+len, "%-10s %2d\n",
ld->name ? ld->name : "???", i);
tty_ldisc_put(i);
if (len+begin > off+count)
break;
if (len+begin < off) {
begin += len;
len = 0;
}
}
if (i >= NR_LDISCS)
*eof = 1;
if (off >= len+begin)
return 0;
*start = page + (off-begin);
return ((count < begin+len-off) ? count : begin+len-off);
}
/*
* 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->read_proc && !driver->write_proc) ||
!driver->driver_name ||
driver->proc_entry)
return;
ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
if (!ent)
return;
ent->read_proc = driver->read_proc;
ent->write_proc = driver->write_proc;
ent->owner = driver->owner;
ent->data = 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)
{
struct proc_dir_entry *entry;
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);
create_proc_read_entry("tty/ldiscs", 0, NULL, tty_ldiscs_read_proc, NULL);
entry = create_proc_entry("tty/drivers", 0, NULL);
if (entry)
entry->proc_fops = &proc_tty_drivers_operations;
}