much like /proc/sys/kernel/modules_disable is used to disable module
loading, /proc/sys/kernel/kexec_disable is used to disable kexec code
loading. It would still be possible to use kexec -l to load a kernel, set
the tunable to 1 so the kernel waiting to boot couldn't change, and then
launch the kernel at a later time (through kexec -e or through a crash)
Signed-off-by: Eric Paris <eparis at redhat.com>
---
include/linux/kexec.h | 2 ++
kernel/kexec.c | 4 ++++
kernel/sysctl.c | 13 +++++++++++++
3 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 03e8e8d..fd8b2b8 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -195,6 +195,8 @@ extern struct kimage *kexec_crash_image;
#define VMCOREINFO_NOTE_SIZE (KEXEC_NOTE_HEAD_BYTES*2 + VMCOREINFO_BYTES \
+ VMCOREINFO_NOTE_NAME_BYTES)
+extern int kexec_load_disabled;
+
/* Location of a reserved region to hold the crash kernel.
*/
extern struct resource crashk_res;
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 213ce69..5aff5cd 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -48,6 +48,7 @@ static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
size_t vmcoreinfo_size;
size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
+int kexec_load_disabled;
/* Location of the reserved area for the crash kernel */
struct resource crashk_res = {
@@ -949,6 +950,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
!capable(CAP_SYS_MODULE))
return -EPERM;
+ if (kexec_load_disabled)
+ return -EPERM;
+
/*
* Verify we have a legal set of flags
* This leaves us room for future extensions.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0e1ac51..1fdc973 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -55,6 +55,7 @@
#include <linux/kprobes.h>
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
+#include <linux/kexec.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -569,6 +570,18 @@ static struct ctl_table kern_table[] = {
.extra2 = &one,
},
#endif
+#ifdef CONFIG_KEXEC
+ {
+ .procname = "kexec_load_disabled",
+ .data = &kexec_load_disabled,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ /* only handle a transition from default "0" to "1" */
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
+ .extra2 = &one,
+ },
+#endif
#ifdef CONFIG_HOTPLUG
{
.procname = "hotplug",
