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

[Coiby Xu]

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@xxxxxxxxxxxxxxxxxxx
> > > Cc: keyrings@xxxxxxxxxxxxxxx
> > > Cc: linux-security-module@xxxxxxxxxxxxxxx
> > > Cc: stable@xxxxxxxxxxxxxxx # 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@xxxxxxx>
> > > Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
> > > ---
> >
> > 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@xxxxxxxxxx>
> >
> > >  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