From: Jan Kara <jack@suse.cz>
Attached patch fixes a regression introduced by my patch allowing separate
enabling of magic-sysrq functions. The problem is that originally it was
always possible to use /proc/sysrq-trigger regardless the value of
/proc/sys/kernel/sysrq (which actually I didn't know ;) and my original
patch disallowed it. As I think the original behaviour is more useful and
has no security problems (only root can access sysrq-trigger) the patch
implementing the old behaviour is attached.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/Documentation/sysrq.txt | 4 ++++
25-akpm/drivers/char/sysrq.c | 9 ++++++---
25-akpm/fs/proc/proc_misc.c | 2 +-
25-akpm/include/linux/sysrq.h | 2 +-
4 files changed, 12 insertions(+), 5 deletions(-)
diff -puN Documentation/sysrq.txt~fix-partial-sysrq-setting Documentation/sysrq.txt
--- 25/Documentation/sysrq.txt~fix-partial-sysrq-setting Wed Feb 9 14:42:56 2005
+++ 25-akpm/Documentation/sysrq.txt Wed Feb 9 14:42:56 2005
@@ -33,6 +33,10 @@ in /proc/sys/kernel/sysrq:
You can set the value in the file by the following command:
echo "number" >/proc/sys/kernel/sysrq
+Note that the value of /proc/sys/kernel/sysrq influences only the invocation
+via a keyboard. Invocation of any operation via /proc/sysrq-trigger is always
+allowed.
+
* How do I use the magic SysRq key?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
On x86 - You press the key combo 'ALT-SysRq-<command key>'. Note - Some
diff -puN drivers/char/sysrq.c~fix-partial-sysrq-setting drivers/char/sysrq.c
--- 25/drivers/char/sysrq.c~fix-partial-sysrq-setting Wed Feb 9 14:42:56 2005
+++ 25-akpm/drivers/char/sysrq.c Wed Feb 9 14:43:59 2005
@@ -345,7 +345,7 @@ void __sysrq_put_key_op (int key, struct
* as they are inside of the lock
*/
-void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
+void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
{
struct sysrq_key_op *op_p;
int orig_log_level;
@@ -359,7 +359,10 @@ void __handle_sysrq(int key, struct pt_r
op_p = __sysrq_get_key_op(key);
if (op_p) {
- if (sysrq_enabled == 1 || sysrq_enabled & op_p->enable_mask) {
+ /* Should we check for enabled operations (/proc/sysrq-trigger should not)
+ * and is the invoked operation enabled? */
+ if (!check_mask || sysrq_enabled == 1 ||
+ (sysrq_enabled & op_p->enable_mask)) {
printk ("%s\n", op_p->action_msg);
console_loglevel = orig_log_level;
op_p->handler(key, pt_regs, tty);
@@ -390,7 +393,7 @@ void handle_sysrq(int key, struct pt_reg
{
if (!sysrq_enabled)
return;
- __handle_sysrq(key, pt_regs, tty);
+ __handle_sysrq(key, pt_regs, tty, 1);
}
int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
diff -puN fs/proc/proc_misc.c~fix-partial-sysrq-setting fs/proc/proc_misc.c
--- 25/fs/proc/proc_misc.c~fix-partial-sysrq-setting Wed Feb 9 14:42:56 2005
+++ 25-akpm/fs/proc/proc_misc.c Wed Feb 9 14:42:56 2005
@@ -524,7 +524,7 @@ static ssize_t write_sysrq_trigger(struc
if (get_user(c, buf))
return -EFAULT;
- __handle_sysrq(c, NULL, NULL);
+ __handle_sysrq(c, NULL, NULL, 0);
}
return count;
}
diff -puN include/linux/sysrq.h~fix-partial-sysrq-setting include/linux/sysrq.h
--- 25/include/linux/sysrq.h~fix-partial-sysrq-setting Wed Feb 9 14:42:56 2005
+++ 25-akpm/include/linux/sysrq.h Wed Feb 9 14:42:56 2005
@@ -42,7 +42,7 @@ struct sysrq_key_op {
*/
void handle_sysrq(int, struct pt_regs *, struct tty_struct *);
-void __handle_sysrq(int, struct pt_regs *, struct tty_struct *);
+void __handle_sysrq(int, struct pt_regs *, struct tty_struct *, int check_mask);
int register_sysrq_key(int, struct sysrq_key_op *);
int unregister_sysrq_key(int, struct sysrq_key_op *);
struct sysrq_key_op *__sysrq_get_key_op(int key);
_