Re: [PATCH v4 2/8] kexec: add call to LSM hook in original kexec_load syscall

Serge E. Hallyn
2018-06-04T20:00:13Z

Quoting Mimi Zohar (zohar@linux.vnet.ibm.com):
> In order for LSMs and IMA-appraisal to differentiate between kexec_load
> and kexec_file_load syscalls, both the original and new syscalls must
> call an LSM hook. This patch adds a call to security_kernel_load_data()
> in the original kexec_load syscall.
>
> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>

Acked-by: Serge Hallyn <serge@hallyn.com>

> Cc: Luis R. Rodriguez <mcgrof@kernel.org>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: David Howells <dhowells@redhat.com>
> ---
> kernel/kexec.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index aed8fb2564b3..68559808fdfa 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -11,6 +11,7 @@
> #include <linux/capability.h>
> #include <linux/mm.h>
> #include <linux/file.h>
> +#include <linux/security.h>
> #include <linux/kexec.h>
> #include <linux/mutex.h>
> #include <linux/list.h>
> @@ -195,10 +196,17 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
> static inline int kexec_load_check(unsigned long nr_segments,
> unsigned long flags)
> {
> + int result;
> +
> /* We only trust the superuser with rebooting the system. */
> if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
> return -EPERM;
>
> + /* Permit LSMs and IMA to fail the kexec */
> + result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
> + if (result < 0)
> + return result;
> +
> /*
> * Verify we have a legal set of flags
> * This leaves us room for future extensions.
> --
> 2.7.5