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SubjectRe: [PATCH 0/3] kexec: refactor CONFIG_KEXEC/CONFIG_KEXEC_FILE Kconfig
On 07/15/15 at 05:16pm, Dave Young wrote:
> On 07/13/15 at 10:13am, Dave Young wrote:
> > Previously Theodore Ts'o brought up an issue about kexec_load syscall bypassing
> > signature verification:
> > https://lkml.org/lkml/2015/6/14/280
> >
> > Because we have two kexec load syscall, one kexec_load, another kexec_file_load,
> > the latter one was introduced by Vivek Goyal, it is mainly for supporting UEFI
> > secure boot. kexec_file_load verifies kernel signature, but even if with
> > CONFIG_KEXEC_VERIFY_SIG=y and CONFIG_KEXEC_FILE=y, kexec-tools still can use
> > old syscall and bypass signature verification.
> >
> > KEXEC_FILE can also be used without UEFI, so kexec can always verify kernel
> > signature for security purpose.
> >
> > The suggestion in above thread is add a new Kconfig option for kexec common
> > code, here I use KEXEC_CORE, KEXEC and KEXEC_FILE select KEXEC_CORE so one can
> > compile only KEXEC_FILE without old kexec_load syscall.
> >
> > There's checkpatch warnings and errors, I would like to send furthuer cleanup
> > patches after this series. Please let me know if you have other suggestions.
> > checkpatch errors are for cases such as assign a value to static variables.
> >
> > PATCH 3/3 can be sort out from the series if people do not like. It is a
> > cleanup for a macro.
>
> Since it is not related to the Kconfig cleanup thus I will drop it in
> next update, will send out as a standalone patch later.
>
> Also there's a kexec-tools patch needed for testing KEXEC_FILE only, I forgot
> to mention, will take it in cover letter when I repost:

BTW, it is the case below:
kernel: CONFIG_KEXEC_FILE only,
kexec-tools: do not use '-s' option, it should check kexec_load(2) earlier
and fail out. but below code is still a fix to a code problem.

kexec -s -p work ok without the fix.

>
> ---
> kexec/crashdump-elf.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> --- kexec-tools.orig/kexec/crashdump-elf.c
> +++ kexec-tools/kexec/crashdump-elf.c
> @@ -145,11 +145,12 @@ int FUNC(struct kexec_info *info,
>
> count_cpu = nr_cpus;
> for (i = 0; count_cpu > 0; i++) {
> - if (get_note_info(i, &notes_addr, &notes_len) < 0) {
> - /* This cpu is not present. Skip it. */
> - continue;
> - }
> + int ret;
> +
> + ret = get_note_info(i, &notes_addr, &notes_len);
> count_cpu--;
> + if (ret < 0) /* This cpu is not present. Skip it. */
> + continue;
>
> phdr = (PHDR *) bufp;
> bufp += sizeof(PHDR);
>
> Thanks
> Dave
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
>
>


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