From: Chun-Yi Lee Date: Wed, 8 Nov 2017 15:11:33 +0000 Subject: [08/29] kexec_file: Restrict at runtime if the kernel is locked down Origin: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit?id=eed4aca0409692d7d24bc64f5c98d346cd0506c4 When KEXEC_VERIFY_SIG is not enabled, kernel should not load images through kexec_file systemcall if the kernel is locked down unless IMA can be used to validate the image. This code was showed in Matthew's patch but not in git: https://lkml.org/lkml/2015/3/13/778 Cc: Matthew Garrett Signed-off-by: Chun-Yi Lee Signed-off-by: David Howells Reviewed-by: James Morris cc: kexec@lists.infradead.org --- kernel/kexec_file.c | 8 ++++++++ 1 file changed, 8 insertions(+) Index: linux/kernel/kexec_file.c =================================================================== --- linux.orig/kernel/kexec_file.c +++ linux/kernel/kexec_file.c @@ -328,6 +328,14 @@ SYSCALL_DEFINE5(kexec_file_load, int, ke if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; + /* Don't permit images to be loaded into trusted kernels if we're not + * going to verify the signature on them + */ + if (!IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) && + !is_ima_appraise_enabled() && + kernel_is_locked_down("kexec of unsigned images")) + return -EPERM; + /* Make sure we have a legal set of flags */ if (flags != (flags & KEXEC_FILE_FLAGS)) return -EINVAL;