2022-04-03 17:47:07

by Coiby Xu

Subject: [PATCH v5 3/3] arm64: kexec_file: use more system keyrings to verify kernel image signature

Currently, a problem faced by arm64 is if a kernel image is signed by a
MOK key, loading it via the kexec_file_load() system call would be
rejected with the error "Lockdown: kexec: kexec of unsigned images is
restricted; see man kernel_lockdown.7".

This patch allows to verify arm64 kernel image signature using not only
.builtin_trusted_keys but also .platform and .secondary_trusted_key
keyring.

Acked-by: Will Deacon <[email protected]>
Signed-off-by: Coiby Xu <[email protected]>
---
arch/arm64/kernel/kexec_image.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index 9ec34690e255..51af1c22d6da 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -14,7 +14,6 @@
#include <linux/kexec.h>
#include <linux/pe.h>
#include <linux/string.h>
-#include <linux/verification.h>
#include <asm/byteorder.h>
#include <asm/cpufeature.h>
#include <asm/image.h>
@@ -133,8 +132,7 @@ static void *image_load(struct kimage *image,
#ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
static int image_verify_sig(const char *kernel, unsigned long kernel_len)
{
- return verify_pefile_signature(kernel, kernel_len, NULL,
- VERIFYING_KEXEC_PE_SIGNATURE);
+ return kexec_kernel_verify_pe_sig(kernel, kernel_len);
}
#endif

--
2.34.1

2022-04-12 09:49:59

by Michal Suchánek

Subject: Re: [PATCH v5 3/3] arm64: kexec_file: use more system keyrings to verify kernel image signature

On Fri, Apr 01, 2022 at 09:31:18AM +0800, Coiby Xu wrote:
> Currently, a problem faced by arm64 is if a kernel image is signed by a
> MOK key, loading it via the kexec_file_load() system call would be
> rejected with the error "Lockdown: kexec: kexec of unsigned images is
> restricted; see man kernel_lockdown.7".

This is because image_verify_sig uses only the primary keyring that
contains only kernel built-in keys to verify the kexec image.

> This patch allows to verify arm64 kernel image signature using not only
> .builtin_trusted_keys but also .platform and .secondary_trusted_key
> keyring.
>
> Acked-by: Will Deacon <[email protected]>
> Signed-off-by: Coiby Xu <[email protected]>
> ---
> arch/arm64/kernel/kexec_image.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
> index 9ec34690e255..51af1c22d6da 100644
> --- a/arch/arm64/kernel/kexec_image.c
> +++ b/arch/arm64/kernel/kexec_image.c
> @@ -14,7 +14,6 @@
> #include <linux/kexec.h>
> #include <linux/pe.h>
> #include <linux/string.h>
> -#include <linux/verification.h>
> #include <asm/byteorder.h>
> #include <asm/cpufeature.h>
> #include <asm/image.h>
> @@ -133,8 +132,7 @@ static void *image_load(struct kimage *image,
> #ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
> static int image_verify_sig(const char *kernel, unsigned long kernel_len)
> {
> - return verify_pefile_signature(kernel, kernel_len, NULL,
> - VERIFYING_KEXEC_PE_SIGNATURE);
> + return kexec_kernel_verify_pe_sig(kernel, kernel_len);
> }
> #endif

You can eliminate image_verify_sig here aswell and directly assign
kexec_kernel_verify_pe_sig to fops.

Thanks

Michal

2022-04-14 15:00:30

by Coiby Xu

Subject: Re: [PATCH v5 3/3] arm64: kexec_file: use more system keyrings to verify kernel image signature

On Mon, Apr 11, 2022 at 10:59:38AM +0200, Michal Such?nek wrote:
>On Fri, Apr 01, 2022 at 09:31:18AM +0800, Coiby Xu wrote:
>> Currently, a problem faced by arm64 is if a kernel image is signed by a
>> MOK key, loading it via the kexec_file_load() system call would be
>> rejected with the error "Lockdown: kexec: kexec of unsigned images is
>> restricted; see man kernel_lockdown.7".
>
>This is because image_verify_sig uses only the primary keyring that
>contains only kernel built-in keys to verify the kexec image.
>
>> This patch allows to verify arm64 kernel image signature using not only
>> .builtin_trusted_keys but also .platform and .secondary_trusted_key
>> keyring.
>>
>> Acked-by: Will Deacon <[email protected]>
>> Signed-off-by: Coiby Xu <[email protected]>
>> ---
>> arch/arm64/kernel/kexec_image.c | 4 +---
>> 1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
>> index 9ec34690e255..51af1c22d6da 100644
>> --- a/arch/arm64/kernel/kexec_image.c
>> +++ b/arch/arm64/kernel/kexec_image.c
>> @@ -14,7 +14,6 @@
>> #include <linux/kexec.h>
>> #include <linux/pe.h>
>> #include <linux/string.h>
>> -#include <linux/verification.h>
>> #include <asm/byteorder.h>
>> #include <asm/cpufeature.h>
>> #include <asm/image.h>
>> @@ -133,8 +132,7 @@ static void *image_load(struct kimage *image,
>> #ifdef CONFIG_KEXEC_IMAGE_VERIFY_SIG
>> static int image_verify_sig(const char *kernel, unsigned long kernel_len)
>> {
>> - return verify_pefile_signature(kernel, kernel_len, NULL,
>> - VERIFYING_KEXEC_PE_SIGNATURE);
>> + return kexec_kernel_verify_pe_sig(kernel, kernel_len);
>> }
>> #endif
>
>You can eliminate image_verify_sig here aswell and directly assign
>kexec_kernel_verify_pe_sig to fops.

Good suggestions, thanks!

>
>Thanks
>
>Michal
>

--
Best regards,
Coiby