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Message-ID: <20211012035324.ctwuaaaig5yin7ve@localhost.localdomain>
Date: Tue, 12 Oct 2021 11:53:24 +0800
From: Coiby Xu <coxu@...hat.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
Dave Young <dyoung@...hat.com>, Will Deacon <will@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] kexec, KEYS: make the code in
bzImage64_verify_sig generic
On Mon, Oct 11, 2021 at 08:58:36AM -0500, Eric W. Biederman wrote:
>Coiby Xu <coxu@...hat.com> writes:
>
>> The code in bzImage64_verify_sig could make use of system keyrings including
>> .buitin_trusted_keys, .secondary_trusted_keys and .platform keyring to verify
>> signed kernel image as PE file. Make it generic so both x86_64 and arm64 can
>> use it.
>
>The naming is problematic.
>
>At a minimum please name the new function kexec_kernel_verify_pe_sig.
>AKA what you named it without the "arch_" prefix. A function named with
>an "arch_" prefix implies that it has an architecture specific
>implementation.
Thanks for bringing up this issue and providing the fix and the explanation.
>
>It looks like arch_kexec_kernel_verify_sig should be killed as well
>as it only has one implementation in the generic code. And the code
>should always call kexec_image_verify_sig_default. Not that you should
>do that but I am pointing it out as it seems that is the bad example you
>are copying.
Yes, you are right about it. This is a leftover issue of commit
9ec4ecef0af7790551109283ca039a7c52de343c ("kexec_file,x86,powerpc: factor
out kexec_file_ops functions"),
As arch_kexec_kernel_image_{probe,load}(),
arch_kimage_file_post_load_cleanup() and arch_kexec_kernel_verify_sig()
are almost duplicated among architectures, they can be commonalized with
an architecture-defined kexec_file_ops array. So let's factor them out.
That commit moves the architecture specific implementation of
arch_kexec_kernel_verify_sig to kexec_file_ops->verify_sig. So actually
arch_kexec_kernel_verify_sig should be removed. Then we rename
kexec_image_verify_sig_default to kimage_validate_signature and call
it in kimage_validate_signature directly. I'll include a new patch to do
the clean-up work in v3.
>
>Eric
>
>> Signed-off-by: Coiby Xu <coxu@...hat.com>
>> ---
>> arch/x86/kernel/kexec-bzimage64.c | 13 +------------
>> include/linux/kexec.h | 3 +++
>> kernel/kexec_file.c | 17 +++++++++++++++++
>> 3 files changed, 21 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
>> index 170d0fd68b1f..4136dd3be5a9 100644
>> --- a/arch/x86/kernel/kexec-bzimage64.c
>> +++ b/arch/x86/kernel/kexec-bzimage64.c
>> @@ -17,7 +17,6 @@
>> #include <linux/kernel.h>
>> #include <linux/mm.h>
>> #include <linux/efi.h>
>> -#include <linux/verification.h>
>>
>> #include <asm/bootparam.h>
>> #include <asm/setup.h>
>> @@ -531,17 +530,7 @@ static int bzImage64_cleanup(void *loader_data)
>> #ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
>> static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
>> {
>> - int ret;
>> -
>> - ret = verify_pefile_signature(kernel, kernel_len,
>> - VERIFY_USE_SECONDARY_KEYRING,
>> - VERIFYING_KEXEC_PE_SIGNATURE);
>> - if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
>> - ret = verify_pefile_signature(kernel, kernel_len,
>> - VERIFY_USE_PLATFORM_KEYRING,
>> - VERIFYING_KEXEC_PE_SIGNATURE);
>> - }
>> - return ret;
>> + return arch_kexec_kernel_verify_pe_sig(kernel, kernel_len);
>> }
>> #endif
>>
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index 0c994ae37729..d45f32336dbe 100644
>> --- a/include/linux/kexec.h
>> +++ b/include/linux/kexec.h
>> @@ -19,6 +19,7 @@
>> #include <asm/io.h>
>>
>> #include <uapi/linux/kexec.h>
>> +#include <linux/verification.h>
>>
>> #ifdef CONFIG_KEXEC_CORE
>> #include <linux/list.h>
>> @@ -199,6 +200,8 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image);
>> #ifdef CONFIG_KEXEC_SIG
>> int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
>> unsigned long buf_len);
>> +int arch_kexec_kernel_verify_pe_sig(const char *kernel,
>> + unsigned long kernel_len);
>> #endif
>> int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf);
>>
>> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
>> index 33400ff051a8..0530275b7aa3 100644
>> --- a/kernel/kexec_file.c
>> +++ b/kernel/kexec_file.c
>> @@ -106,6 +106,23 @@ int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
>> {
>> return kexec_image_verify_sig_default(image, buf, buf_len);
>> }
>> +
>> +#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
>> +int arch_kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
>> +{
>> + int ret;
>> +
>> + ret = verify_pefile_signature(kernel, kernel_len,
>> + VERIFY_USE_SECONDARY_KEYRING,
>> + VERIFYING_KEXEC_PE_SIGNATURE);
>> + if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
>> + ret = verify_pefile_signature(kernel, kernel_len,
>> + VERIFY_USE_PLATFORM_KEYRING,
>> + VERIFYING_KEXEC_PE_SIGNATURE);
>> + }
>> + return ret;
>> +}
>> +#endif
>> #endif
>>
>> /*
>
--
Best regards,
Coiby
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