| From | Matthew Garrett <> | Subject | [PATCH 08/12] kexec: Disable at runtime if securelevel has been set. | Date | Mon, 9 Sep 2013 11:49:42 -0400 |
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kexec permits the loading and execution of arbitrary code in ring 0, which permits the modification of the running kernel. Prevent this if securelevel has been set.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> --- kernel/kexec.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/kexec.c b/kernel/kexec.c index 59f7b55..98db2a1 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -32,6 +32,7 @@ #include <linux/vmalloc.h> #include <linux/swap.h> #include <linux/syscore_ops.h> +#include <linux/security.h> #include <asm/page.h> #include <asm/uaccess.h> @@ -942,6 +943,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, if (!capable(CAP_SYS_BOOT)) return -EPERM; + if (get_securelevel() > 0) + return -EPERM; + /* * Verify we have a legal set of flags * This leaves us room for future extensions. -- 1.8.3.1
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