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authorMatthew Garrett <mjg59@srcf.ucam.org>2019-08-20 02:17:42 +0200
committerJames Morris <jmorris@namei.org>2019-08-20 06:54:15 +0200
commit7d31f4602f8d366072471ca138e4ea7b8edf9be0 (patch)
treed6c84bb75d5972c3c2ba086f6e7179d82f36393d /kernel
parentlockdown: Restrict /dev/{mem,kmem,port} when the kernel is locked down (diff)
downloadlinux-7d31f4602f8d366072471ca138e4ea7b8edf9be0.tar.xz
linux-7d31f4602f8d366072471ca138e4ea7b8edf9be0.zip
kexec_load: Disable at runtime if the kernel is locked down
The kexec_load() syscall permits the loading and execution of arbitrary code in ring 0, which is something that lock-down is meant to prevent. It makes sense to disable kexec_load() in this situation. This does not affect kexec_file_load() syscall which can check for a signature on the image to be booted. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Dave Young <dyoung@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> cc: kexec@lists.infradead.org Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kexec.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 1b018f1a6e0d..bc933c0db9bf 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -206,6 +206,14 @@ static inline int kexec_load_check(unsigned long nr_segments,
return result;
/*
+ * kexec can be used to circumvent module loading restrictions, so
+ * prevent loading in that case
+ */
+ result = security_locked_down(LOCKDOWN_KEXEC);
+ if (result)
+ return result;
+
+ /*
* Verify we have a legal set of flags
* This leaves us room for future extensions.
*/