Re: [PATCH v7 2/4] kexec, KEYS: make the code in bzImage64_verify_sig generic

[Coiby Xu <coxu@redhat.com>]

On Thu, May 12, 2022 at 11:52:09AM +0800, Baoquan He wrote:
>On 05/12/22 at 10:46am, Baoquan He wrote:
>> On 05/12/22 at 10:34am, Coiby Xu wrote:
>> > commit 278311e417be ("kexec, KEYS: Make use of platform keyring for
>> > signature verify") adds platform keyring support on x86 kexec but not
>> > arm64.
>> >
>> > The code in bzImage64_verify_sig makes 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.
>> >
>> > Note this patch is needed by a later patch so Cc it to the stable tree
>> > as well.
>>
>> This note should not be added in log.
>>
>> >
>> > Cc: kexec@lists.infradead.org
>> > Cc: keyrings@vger.kernel.org
>> > Cc: linux-security-module@vger.kernel.org
>> > Cc: stable@vger.kernel.org # 34d5960af253: kexec: clean up arch_kexec_kernel_verify_sig
>
>Hold on, should we CC stable when it's not fixing an issue?
>
>Hi Coiby,

Hi Baoquan,

>
>Just to make clear , is this patch fixing an issue, or it's just an
>preparation for later patch's use?
>
>Or I should ask in another way, any problem is solved with this patch?

At least it doesn't fix an issue that satisfy the criteria listed in 
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html

>
>
>> > Reviewed-by: Michal Suchanek <msuchanek@suse.de>
>> > Signed-off-by: Coiby Xu <coxu@redhat.com>
>> > ---
>>
>> You can put the note here, it won't be added to commit log when merged.
>> Maybe it can be removed when merged.

Thanks for the suggestion! Shall I send a version to fix this problem or
can I just bother the maintainer to remove it?


>>
>> Otherwise, LGTM
>>
>> Acked-by: Baoquan He <bhe@redhat.com>
>>
>> >  arch/x86/kernel/kexec-bzimage64.c | 20 +-------------------
>> >  include/linux/kexec.h             |  7 +++++++
>> >  kernel/kexec_file.c               | 17 +++++++++++++++++
>> >  3 files changed, 25 insertions(+), 19 deletions(-)
>> >
>> > diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
>> > index 170d0fd68b1f..f299b48f9c9f 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>
>> > @@ -528,28 +527,11 @@ static int bzImage64_cleanup(void *loader_data)
>> >  	return 0;
>> >  }
>> >
>> > -#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;
>> > -}
>> > -#endif
>> > -
>> >  const struct kexec_file_ops kexec_bzImage64_ops = {
>> >  	.probe = bzImage64_probe,
>> >  	.load = bzImage64_load,
>> >  	.cleanup = bzImage64_cleanup,
>> >  #ifdef CONFIG_KEXEC_BZIMAGE_VERIFY_SIG
>> > -	.verify_sig = bzImage64_verify_sig,
>> > +	.verify_sig = kexec_kernel_verify_pe_sig,
>> >  #endif
>> >  };
>> > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> > index 413235c6c797..da83abfc628b 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>
>> >
>> >  /* Location of a reserved region to hold the crash kernel.
>> >   */
>> > @@ -202,6 +203,12 @@ int arch_kexec_apply_relocations(struct purgatory_info *pi,
>> >  				 const Elf_Shdr *relsec,
>> >  				 const Elf_Shdr *symtab);
>> >  int arch_kimage_file_post_load_cleanup(struct kimage *image);
>> > +#ifdef CONFIG_KEXEC_SIG
>> > +#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
>> > +int kexec_kernel_verify_pe_sig(const char *kernel,
>> > +				    unsigned long kernel_len);
>> > +#endif
>> > +#endif
>> >  int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf);
>> >
>> >  extern int kexec_add_buffer(struct kexec_buf *kbuf);
>> > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
>> > index 3720435807eb..754885b96aab 100644
>> > --- a/kernel/kexec_file.c
>> > +++ b/kernel/kexec_file.c
>> > @@ -165,6 +165,23 @@ void kimage_file_post_load_cleanup(struct kimage *image)
>> >  }
>> >
>> >  #ifdef CONFIG_KEXEC_SIG
>> > +#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
>> > +int 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
>> > +
>> >  static int kexec_image_verify_sig(struct kimage *image, void *buf,
>> >  		unsigned long buf_len)
>> >  {
>> > --
>> > 2.35.3
>> >
>>
>

-- 
Best regards,
Coiby