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Input: implement SysRq as a separate input handler

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Instead of keeping SysRq support inside of legacy keyboard driver split
it out into a separate input handler (filter). This stops most SysRq input
events from leaking into evdev clients (some events, such as first SysRq
scancode - not keycode - event, are still leaked into both legacy keyboard
and evdev).

[martinez.javier@gmail.com: fix compile error when CONFIG_MAGIC_SYSRQ is
 not defined]
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Dmitry Torokhov 2010-03-21 22:31:26 -07:00
parent b91c4be730
commit 97f5f0cd8c
4 changed files with 249 additions and 86 deletions
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40
drivers/char/keyboard.c
View File

@ -38,7 +38,6 @@
#include <linux/kbd_kern.h>
#include <linux/kbd_diacr.h>
#include <linux/vt_kern.h>
#include <linux/sysrq.h>
#include <linux/input.h>
#include <linux/reboot.h>
#include <linux/notifier.h>
@ -82,8 +81,7 @@ void compute_shiftstate(void);
typedef void (k_handler_fn)(struct vc_data *vc, unsigned char value,
char up_flag);
static k_handler_fn K_HANDLERS;
k_handler_fn *k_handler[16] = { K_HANDLERS };
EXPORT_SYMBOL_GPL(k_handler);
static k_handler_fn *k_handler[16] = { K_HANDLERS };
#define FN_HANDLERS\
fn_null, fn_enter, fn_show_ptregs, fn_show_mem,\
@ -147,22 +145,6 @@ static struct ledptr {
unsigned char valid:1;
} ledptrs[3];
/* Simple translation table for the SysRq keys */
#ifdef CONFIG_MAGIC_SYSRQ
unsigned char kbd_sysrq_xlate[KEY_MAX + 1] =
"\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
"qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
"dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
"bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
"\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
"230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
"\r\000/"; /* 0x60 - 0x6f */
static int sysrq_down;
static int sysrq_alt_use;
#endif
static int sysrq_alt;
/*
* Notifier list for console keyboard events
*/
@ -1108,7 +1090,8 @@ static int emulate_raw(struct vc_data *vc, unsigned int keycode,
* pressing PrtSc/SysRq alone, but simply 0x54
* when pressing Alt+PrtSc/SysRq.
*/
if (sysrq_alt) {
if (test_bit(KEY_LEFTALT, key_down) ||
test_bit(KEY_RIGHTALT, key_down)) {
put_queue(vc, 0x54 | up_flag);
} else {
put_queue(vc, 0xe0);
@ -1176,8 +1159,6 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
kbd = kbd_table + vc->vc_num;
if (keycode == KEY_LEFTALT || keycode == KEY_RIGHTALT)
sysrq_alt = down ? keycode : 0;
#ifdef CONFIG_SPARC
if (keycode == KEY_STOP)
sparc_l1_a_state = down;
@ -1190,21 +1171,6 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
if (keycode < BTN_MISC && printk_ratelimit())
printk(KERN_WARNING "keyboard.c: can't emulate rawmode for keycode %d\n", keycode);
#ifdef CONFIG_MAGIC_SYSRQ /* Handle the SysRq Hack */
if (keycode == KEY_SYSRQ && (sysrq_down || (down == 1 && sysrq_alt))) {
if (!sysrq_down) {
sysrq_down = down;
sysrq_alt_use = sysrq_alt;
}
return;
}
if (sysrq_down && !down && keycode == sysrq_alt_use)
sysrq_down = 0;
if (sysrq_down && down && !rep) {
handle_sysrq(kbd_sysrq_xlate[keycode], tty);
return;
}
#endif
#ifdef CONFIG_SPARC
if (keycode == KEY_A && sparc_l1_a_state) {
sparc_l1_a_state = 0;

243
drivers/char/sysrq.c
View File

@ -1,7 +1,4 @@
/* -*- linux-c -*-
*
* $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
*
/*
* Linux Magic System Request Key Hacks
*
* (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
@ -10,8 +7,13 @@
* (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
* overhauled to use key registration
* based upon discusions in irc://irc.openprojects.net/#kernelnewbies
*
* Copyright (c) 2010 Dmitry Torokhov
* Input handler conversion
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
@ -39,33 +41,34 @@
#include <linux/hrtimer.h>
#include <linux/oom.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <asm/ptrace.h>
#include <asm/irq_regs.h>
/* Whether we react on sysrq keys or just ignore them */
int __read_mostly __sysrq_enabled = 1;
static int __read_mostly sysrq_enabled = 1;
static bool __read_mostly sysrq_always_enabled;
static int __read_mostly sysrq_always_enabled;
int sysrq_on(void)
static bool sysrq_on(void)
{
return __sysrq_enabled || sysrq_always_enabled;
return sysrq_enabled || sysrq_always_enabled;
}
/*
* A value of 1 means 'all', other nonzero values are an op mask:
*/
static inline int sysrq_on_mask(int mask)
static bool sysrq_on_mask(int mask)
{
return sysrq_always_enabled || __sysrq_enabled == 1 ||
(__sysrq_enabled & mask);
return sysrq_always_enabled ||
sysrq_enabled == 1 ||
(sysrq_enabled & mask);
}
static int __init sysrq_always_enabled_setup(char *str)
{
sysrq_always_enabled = 1;
printk(KERN_INFO "debug: sysrq always enabled.\n");
sysrq_always_enabled = true;
pr_info("sysrq always enabled.\n");
return 1;
}
@ -76,6 +79,7 @@ __setup("sysrq_always_enabled", sysrq_always_enabled_setup);
static void sysrq_handle_loglevel(int key, struct tty_struct *tty)
{
int i;
i = key - '0';
console_loglevel = 7;
printk("Loglevel set to %d\n", i);
@ -101,7 +105,7 @@ static struct sysrq_key_op sysrq_SAK_op = {
.enable_mask = SYSRQ_ENABLE_KEYBOARD,
};
#else
#define sysrq_SAK_op (*(struct sysrq_key_op *)0)
#define sysrq_SAK_op (*(struct sysrq_key_op *)NULL)
#endif
#ifdef CONFIG_VT
@ -119,7 +123,7 @@ static struct sysrq_key_op sysrq_unraw_op = {
.enable_mask = SYSRQ_ENABLE_KEYBOARD,
};
#else
#define sysrq_unraw_op (*(struct sysrq_key_op *)0)
#define sysrq_unraw_op (*(struct sysrq_key_op *)NULL)
#endif /* CONFIG_VT */
static void sysrq_handle_crash(int key, struct tty_struct *tty)
@ -195,7 +199,7 @@ static struct sysrq_key_op sysrq_showlocks_op = {
.action_msg = "Show Locks Held",
};
#else
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
#define sysrq_showlocks_op (*(struct sysrq_key_op *)NULL)
#endif
#ifdef CONFIG_SMP
@ -298,7 +302,7 @@ static struct sysrq_key_op sysrq_ftrace_dump_op = {
.enable_mask = SYSRQ_ENABLE_DUMP,
};
#else
#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)0)
#define sysrq_ftrace_dump_op (*(struct sysrq_key_op *)NULL)
#endif
static void sysrq_handle_showmem(int key, struct tty_struct *tty)
@ -477,6 +481,7 @@ struct sysrq_key_op *__sysrq_get_key_op(int key)
i = sysrq_key_table_key2index(key);
if (i != -1)
op_p = sysrq_key_table[i];
return op_p;
}
@ -488,11 +493,7 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
sysrq_key_table[i] = op_p;
}
/*
* This is the non-locking version of handle_sysrq. It must/can only be called
* by sysrq key handlers, as they are inside of the lock
*/
void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
static void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
{
struct sysrq_key_op *op_p;
int orig_log_level;
@ -544,10 +545,6 @@ void __handle_sysrq(int key, struct tty_struct *tty, int check_mask)
spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
}
/*
* This function is called by the keyboard handler when SysRq is pressed
* and any other keycode arrives.
*/
void handle_sysrq(int key, struct tty_struct *tty)
{
if (sysrq_on())
@ -555,10 +552,177 @@ void handle_sysrq(int key, struct tty_struct *tty)
}
EXPORT_SYMBOL(handle_sysrq);
#ifdef CONFIG_INPUT
/* Simple translation table for the SysRq keys */
static const unsigned char sysrq_xlate[KEY_MAX + 1] =
"\000\0331234567890-=\177\t" /* 0x00 - 0x0f */
"qwertyuiop[]\r\000as" /* 0x10 - 0x1f */
"dfghjkl;'`\000\\zxcv" /* 0x20 - 0x2f */
"bnm,./\000*\000 \000\201\202\203\204\205" /* 0x30 - 0x3f */
"\206\207\210\211\212\000\000789-456+1" /* 0x40 - 0x4f */
"230\177\000\000\213\214\000\000\000\000\000\000\000\000\000\000" /* 0x50 - 0x5f */
"\r\000/"; /* 0x60 - 0x6f */
static bool sysrq_down;
static int sysrq_alt_use;
static int sysrq_alt;
static bool sysrq_filter(struct input_handle *handle, unsigned int type,
unsigned int code, int value)
{
if (type != EV_KEY)
goto out;
switch (code) {
case KEY_LEFTALT:
case KEY_RIGHTALT:
if (value)
sysrq_alt = code;
else if (sysrq_down && code == sysrq_alt_use)
sysrq_down = false;
break;
case KEY_SYSRQ:
if (value == 1 && sysrq_alt) {
sysrq_down = true;
sysrq_alt_use = sysrq_alt;
}
break;
default:
if (sysrq_down && value && value != 2)
__handle_sysrq(sysrq_xlate[code], NULL, 1);
break;
}
out:
return sysrq_down;
}
static int sysrq_connect(struct input_handler *handler,
struct input_dev *dev,
const struct input_device_id *id)
{
struct input_handle *handle;
int error;
sysrq_down = false;
sysrq_alt = 0;
handle = kzalloc(sizeof(struct input_handle), GFP_KERNEL);
if (!handle)
return -ENOMEM;
handle->dev = dev;
handle->handler = handler;
handle->name = "sysrq";
error = input_register_handle(handle);
if (error) {
pr_err("Failed to register input sysrq handler, error %d\n",
error);
goto err_free;
}
error = input_open_device(handle);
if (error) {
pr_err("Failed to open input device, error %d\n", error);
goto err_unregister;
}
return 0;
err_unregister:
input_unregister_handle(handle);
err_free:
kfree(handle);
return error;
}
static void sysrq_disconnect(struct input_handle *handle)
{
input_close_device(handle);
input_unregister_handle(handle);
kfree(handle);
}
/*
* We are matching on KEY_LEFTALT insteard of KEY_SYSRQ because not all
* keyboards have SysRq ikey predefined and so user may add it to keymap
* later, but we expect all such keyboards to have left alt.
*/
static const struct input_device_id sysrq_ids[] = {
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
INPUT_DEVICE_ID_MATCH_KEYBIT,
.evbit = { BIT_MASK(EV_KEY) },
.keybit = { BIT_MASK(KEY_LEFTALT) },
},
{ },
};
static struct input_handler sysrq_handler = {
.filter = sysrq_filter,
.connect = sysrq_connect,
.disconnect = sysrq_disconnect,
.name = "sysrq",
.id_table = sysrq_ids,
};
static bool sysrq_handler_registered;
static inline void sysrq_register_handler(void)
{
int error;
error = input_register_handler(&sysrq_handler);
if (error)
pr_err("Failed to register input handler, error %d", error);
else
sysrq_handler_registered = true;
}
static inline void sysrq_unregister_handler(void)
{
if (sysrq_handler_registered) {
input_unregister_handler(&sysrq_handler);
sysrq_handler_registered = false;
}
}
#else
static inline void sysrq_register_handler(void)
{
}
static inline void sysrq_unregister_handler(void)
{
}
#endif /* CONFIG_INPUT */
int sysrq_toggle_support(int enable_mask)
{
bool was_enabled = sysrq_on();
sysrq_enabled = enable_mask;
if (was_enabled != sysrq_on()) {
if (sysrq_on())
sysrq_register_handler();
else
sysrq_unregister_handler();
}
return 0;
}
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
struct sysrq_key_op *remove_op_p)
{
int retval;
unsigned long flags;
@ -599,6 +763,7 @@ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
return -EFAULT;
__handle_sysrq(c, NULL, 0);
}
return count;
}
@ -606,10 +771,28 @@ static const struct file_operations proc_sysrq_trigger_operations = {
.write = write_sysrq_trigger,
};
static void sysrq_init_procfs(void)
{
if (!proc_create("sysrq-trigger", S_IWUSR, NULL,
&proc_sysrq_trigger_operations))
pr_err("Failed to register proc interface\n");
}
#else
static inline void sysrq_init_procfs(void)
{
}
#endif /* CONFIG_PROC_FS */
static int __init sysrq_init(void)
{
proc_create("sysrq-trigger", S_IWUSR, NULL, &proc_sysrq_trigger_operations);
sysrq_init_procfs();
if (sysrq_on())
sysrq_register_handler();
return 0;
}
module_init(sysrq_init);
#endif

29
include/linux/sysrq.h
View File

@ -39,40 +39,33 @@ struct sysrq_key_op {
#ifdef CONFIG_MAGIC_SYSRQ
extern int sysrq_on(void);
/*
* Do not use this one directly:
*/
extern int __sysrq_enabled;
/* Generic SysRq interface -- you may call it from any device driver, supplying
* ASCII code of the key, pointer to registers and kbd/tty structs (if they
* are available -- else NULL's).
*/
void handle_sysrq(int key, struct tty_struct *tty);
void __handle_sysrq(int key, struct tty_struct *tty, int check_mask);
int register_sysrq_key(int key, struct sysrq_key_op *op);
int unregister_sysrq_key(int key, struct sysrq_key_op *op);
struct sysrq_key_op *__sysrq_get_key_op(int key);
int sysrq_toggle_support(int enable_mask);
#else
static inline int sysrq_on(void)
{
return 0;
}
static inline int __reterr(void)
{
return -EINVAL;
}
static inline void handle_sysrq(int key, struct tty_struct *tty)
{
}
#define register_sysrq_key(ig,nore) __reterr()
#define unregister_sysrq_key(ig,nore) __reterr()
static inline int register_sysrq_key(int key, struct sysrq_key_op *op)
{
return -EINVAL;
}
static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op)
{
return -EINVAL;
}
#endif

23
kernel/sysctl.c
View File

@ -163,6 +163,27 @@ static int proc_taint(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
static int __sysrq_enabled; /* Note: sysrq code ises it's own private copy */
static int sysrq_sysctl_handler(ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int error;
error = proc_dointvec(table, write, buffer, lenp, ppos);
if (error)
return error;
if (write)
sysrq_toggle_support(__sysrq_enabled);
return 0;
}
#endif
static struct ctl_table root_table[];
static struct ctl_table_root sysctl_table_root;
static struct ctl_table_header root_table_header = {
@ -567,7 +588,7 @@ static struct ctl_table kern_table[] = {
.data = &__sysrq_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dointvec,
.proc_handler = sysrq_sysctl_handler,
},
#endif
#ifdef CONFIG_PROC_SYSCTL