Hi,
For all those who said that having magic sysrq enabled on a system was
a security hole:
This patch will add /proc/sys/debug/sysrq_enable. If you:
echo "0">/proc/sys/debug/sysrq_enable
then sysrq won't work. If you:
echo "1">/proc/sys/debug/sysrq_enable
then sysrq will work. "1" is the default setting. Comments? This is
my very first kernel hack, so be gentle :)
-Myrdraal
-- Linux jackalz 2.1.107 #72 Thu Jun 25 01:15:22 EDT 1998 i486 2:11am up 38 min, 15 users, load average: 0.01, 0.01, 0.00--h31gzZEtNLTqOjlF Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="sysrq_enable-2.1.106.diff"
diff -ur linpatch/drivers/char/sysrq.c linux/drivers/char/sysrq.c --- linpatch/drivers/char/sysrq.c Thu Jun 25 01:10:11 1998 +++ linux/drivers/char/sysrq.c Thu Jun 25 00:58:35 1998 @@ -27,6 +27,8 @@ #include <linux/apm_bios.h> #endif +int sysctl_sysrq_enable = 1; + extern void wakeup_bdflush(int); extern void reset_vc(unsigned int); extern int console_loglevel; @@ -57,7 +59,7 @@ { int orig_log_level = console_loglevel; - if (!key) + if (!key || !sysctl_sysrq_enable) return; console_loglevel = 7; diff -ur linpatch/include/linux/sysctl.h linux/include/linux/sysctl.h --- linpatch/include/linux/sysctl.h Thu Jun 25 01:09:30 1998 +++ linux/include/linux/sysctl.h Thu Jun 25 01:03:07 1998 @@ -369,6 +369,9 @@ }; /* CTL_DEBUG names: */ +enum { + DEBUG_SYSRQ_ENABLE = 1, +}; /* CTL_DEV names: */ enum { diff -ur linpatch/kernel/sysctl.c linux/kernel/sysctl.c --- linpatch/kernel/sysctl.c Thu Jun 25 01:10:37 1998 +++ linux/kernel/sysctl.c Thu Jun 25 01:29:02 1998 @@ -41,6 +41,9 @@ extern int bdf_prm[], bdflush_min[], bdflush_max[]; extern char binfmt_java_interpreter[], binfmt_java_appletviewer[]; extern int sysctl_overcommit_memory; +#ifdef CONFIG_MAGIC_SYSRQ +extern int sysctl_sysrq_enable; +#endif #ifdef CONFIG_KMOD extern char modprobe_path[]; #endif @@ -236,6 +239,10 @@ }; static ctl_table debug_table[] = { +#ifdef CONFIG_MAGIC_SYSRQ + {DEBUG_SYSRQ_ENABLE, "sysrq_enable", &sysctl_sysrq_enable, sizeof(int), + 0644, NULL, &proc_dointvec}, +#endif {0} };
--h31gzZEtNLTqOjlF--
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