linux-kernel - Re: [PATCH 1/2] kexec, KEYS: make the code in bzImage64_verify_sig public

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Date:   Thu, 30 Sep 2021 20:52:22 +0800
From:   Dave Young <dyoung@...hat.com>
To:     Coiby Xu <coiby.xu@...il.com>
Cc:     kexec@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
        Coiby Xu <coxu@...hat.com>,
        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>,
        Eric Biederman <ebiederm@...ssion.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] kexec, KEYS: make the code in bzImage64_verify_sig
 public

On 09/30/21 at 08:49pm, Dave Young wrote:
> Hi Coiby,
> On 09/27/21 at 08:50am, Coiby Xu wrote:
> > From: Coiby Xu <coxu@...hat.com>
> > 
> > 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. Move it to a public function.
> > 
> > Signed-off-by: Coiby Xu <coiby.xu@...il.com>
> > ---
> >  arch/x86/kernel/kexec-bzimage64.c | 13 +------------
> >  include/linux/kexec.h             |  3 +++
> >  kernel/kexec_file.c               | 15 +++++++++++++++
> >  3 files changed, 19 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..85ed6984ad8f 100644
> > --- a/kernel/kexec_file.c
> > +++ b/kernel/kexec_file.c
> > @@ -106,6 +106,21 @@ int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> >  {
> >  	return kexec_image_verify_sig_default(image, buf, buf_len);
> >  }
> > +
> > +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;
> > +}
> 
> Since the function is moved as generic code, the kconfig option
> CONFIG_KEXEC_BZIMAGE_VERIFY_SIG can be removed.
> 
> Instead a CONFIG_KEXEC_PEFILE_VERIFY_SIG can be added so that it does
> not need to be compiled for only platform which support UEFI pefile

Fix the sick sentence: I means only to compile for x86_64 and arm64..

> signature verification.  And the related arch kexec_file kconfig can
> just select it.
> 
> Coiby, can you try above?
> 
> >  #endif
> >  
> >  /*
> > -- 
> > 2.33.0
> > 
> > 
> > _______________________________________________
> > kexec mailing list
> > kexec@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
> > 
> > 
> 
> Thanks
> Dave
> 

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