[PATCH v5 1/3] kexec: clean up arch_kexec_kernel_verify_sig

[PATCH v5 1/3] kexec: clean up arch_kexec_kernel_verify_sig

[Coiby Xu]

Currently there is no arch-specific implementation of
arch_kexec_kernel_verify_sig. Even if we want to add an implementation
for an architecture in the future, we can simply use "(struct
kexec_file_ops*)->verify_sig". So clean it up.

Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
---
 include/linux/kexec.h |  4 ----
 kernel/kexec_file.c   | 34 +++++++++++++---------------------
 2 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 0c994ae37729..755fed183224 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -196,10 +196,6 @@ 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
-int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
-				 unsigned long buf_len);
-#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 8347fc158d2b..3720435807eb 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -89,25 +89,6 @@ int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
 	return kexec_image_post_load_cleanup_default(image);
 }
 
-#ifdef CONFIG_KEXEC_SIG
-static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
-					  unsigned long buf_len)
-{
-	if (!image->fops || !image->fops->verify_sig) {
-		pr_debug("kernel loader does not support signature verification.\n");
-		return -EKEYREJECTED;
-	}
-
-	return image->fops->verify_sig(buf, buf_len);
-}
-
-int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
-					unsigned long buf_len)
-{
-	return kexec_image_verify_sig_default(image, buf, buf_len);
-}
-#endif
-
 /*
  * arch_kexec_apply_relocations_add - apply relocations of type RELA
  * @pi:		Purgatory to be relocated.
@@ -184,13 +165,24 @@ void kimage_file_post_load_cleanup(struct kimage *image)
 }
 
 #ifdef CONFIG_KEXEC_SIG
+static int kexec_image_verify_sig(struct kimage *image, void *buf,
+		unsigned long buf_len)
+{
+	if (!image->fops || !image->fops->verify_sig) {
+		pr_debug("kernel loader does not support signature verification.\n");
+		return -EKEYREJECTED;
+	}
+
+	return image->fops->verify_sig(buf, buf_len);
+}
+
 static int
 kimage_validate_signature(struct kimage *image)
 {
 	int ret;
 
-	ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
-					   image->kernel_buf_len);
+	ret = kexec_image_verify_sig(image, image->kernel_buf,
+			image->kernel_buf_len);
 	if (ret) {
 
 		if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
-- 
2.34.1

Re: [PATCH v5 1/3] kexec: clean up arch_kexec_kernel_verify_sig

[Michal Suchánek]

On Fri, Apr 01, 2022 at 09:31:16AM +0800, Coiby Xu wrote:
> Currently there is no arch-specific implementation of
> arch_kexec_kernel_verify_sig. Even if we want to add an implementation
> for an architecture in the future, we can simply use "(struct
> kexec_file_ops*)->verify_sig". So clean it up.
Reviewed-by: Michal Suchanek <msuchanek@suse.de>
> 
> Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
> Signed-off-by: Coiby Xu <coxu@redhat.com>
> ---
>  include/linux/kexec.h |  4 ----
>  kernel/kexec_file.c   | 34 +++++++++++++---------------------
>  2 files changed, 13 insertions(+), 25 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 0c994ae37729..755fed183224 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -196,10 +196,6 @@ 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
> -int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> -				 unsigned long buf_len);
> -#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 8347fc158d2b..3720435807eb 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -89,25 +89,6 @@ int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
>  	return kexec_image_post_load_cleanup_default(image);
>  }
>  
> -#ifdef CONFIG_KEXEC_SIG
> -static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
> -					  unsigned long buf_len)
> -{
> -	if (!image->fops || !image->fops->verify_sig) {
> -		pr_debug("kernel loader does not support signature verification.\n");
> -		return -EKEYREJECTED;
> -	}
> -
> -	return image->fops->verify_sig(buf, buf_len);
> -}
> -
> -int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> -					unsigned long buf_len)
> -{
> -	return kexec_image_verify_sig_default(image, buf, buf_len);
> -}
> -#endif
> -
>  /*
>   * arch_kexec_apply_relocations_add - apply relocations of type RELA
>   * @pi:		Purgatory to be relocated.
> @@ -184,13 +165,24 @@ void kimage_file_post_load_cleanup(struct kimage *image)
>  }
>  
>  #ifdef CONFIG_KEXEC_SIG
> +static int kexec_image_verify_sig(struct kimage *image, void *buf,
> +		unsigned long buf_len)
> +{
> +	if (!image->fops || !image->fops->verify_sig) {
> +		pr_debug("kernel loader does not support signature verification.\n");
> +		return -EKEYREJECTED;
> +	}
> +
> +	return image->fops->verify_sig(buf, buf_len);
> +}
> +
>  static int
>  kimage_validate_signature(struct kimage *image)
>  {
>  	int ret;
>  
> -	ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
> -					   image->kernel_buf_len);
> +	ret = kexec_image_verify_sig(image, image->kernel_buf,
> +			image->kernel_buf_len);
>  	if (ret) {
>  
>  		if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
> -- 
> 2.34.1
> 

[PATCH v5 2/3] kexec, KEYS: make the code in bzImage64_verify_sig generic

[Coiby Xu]

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.

Signed-off-by: Coiby Xu <coxu@redhat.com>
---
 arch/x86/kernel/kexec-bzimage64.c | 13 +------------
 include/linux/kexec.h             |  7 +++++++
 kernel/kexec_file.c               | 17 +++++++++++++++++
 3 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 170d0fd68b1f..f73aab3fde33 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 kexec_kernel_verify_pe_sig(kernel, kernel_len);
 }
 #endif
 
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 755fed183224..2fe39e946988 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>
@@ -196,6 +197,12 @@ 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)
 {
-- 
2.34.1

Re: [PATCH v5 2/3] kexec, KEYS: make the code in bzImage64_verify_sig generic

[Michal Suchánek]

On Fri, Apr 01, 2022 at 09:31:17AM +0800, Coiby Xu wrote:
> The code in bzImage64_verify_sig could make use of system keyrings
s/could make/makes/
> 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.
> 
> Signed-off-by: Coiby Xu <coxu@redhat.com>
> ---
>  arch/x86/kernel/kexec-bzimage64.c | 13 +------------
>  include/linux/kexec.h             |  7 +++++++
>  kernel/kexec_file.c               | 17 +++++++++++++++++
>  3 files changed, 25 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 170d0fd68b1f..f73aab3fde33 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 kexec_kernel_verify_pe_sig(kernel, kernel_len);
>  }

Maybe you can completely eliminate bzImage64_verify_sig and directly
assign kexec_kernel_verify_pe_sig to the fops?

Other than that

Reviewed-by: Michal Suchanek <msuchanek@suse.de>

>  #endif
>  
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 755fed183224..2fe39e946988 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>
> @@ -196,6 +197,12 @@ 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)
>  {
> -- 
> 2.34.1
> 

Re: [PATCH v5 2/3] kexec, KEYS: make the code in bzImage64_verify_sig generic

[Coiby Xu]

On Mon, Apr 11, 2022 at 10:54:11AM +0200, Michal Suchánek wrote:
>On Fri, Apr 01, 2022 at 09:31:17AM +0800, Coiby Xu wrote:
>> The code in bzImage64_verify_sig could make use of system keyrings
>s/could make/makes/
>> 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.
>>
>> Signed-off-by: Coiby Xu <coxu@redhat.com>
>> ---
>>  arch/x86/kernel/kexec-bzimage64.c | 13 +------------
>>  include/linux/kexec.h             |  7 +++++++
>>  kernel/kexec_file.c               | 17 +++++++++++++++++
>>  3 files changed, 25 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
>> index 170d0fd68b1f..f73aab3fde33 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 kexec_kernel_verify_pe_sig(kernel, kernel_len);
>>  }
>
>Maybe you can completely eliminate bzImage64_verify_sig and directly
>assign kexec_kernel_verify_pe_sig to the fops?
>
>Other than that
>
>Reviewed-by: Michal Suchanek <msuchanek@suse.de>

Applied, thanks for the suggestion and reviewing the patch!

>

>>  #endif
>>
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index 755fed183224..2fe39e946988 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>
>> @@ -196,6 +197,12 @@ 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)
>>  {
>> --
>> 2.34.1
>>
>

-- 
Best regards,
Coiby

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

[Coiby Xu]

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 <will@kernel.org>
Signed-off-by: Coiby Xu <coxu@redhat.com>
---
 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

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

[Michal Suchánek]

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 <will@kernel.org>
> Signed-off-by: Coiby Xu <coxu@redhat.com>
> ---
>  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

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

[Coiby Xu]

On Mon, Apr 11, 2022 at 10:59:38AM +0200, Michal Suchánek 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 <will@kernel.org>
>> Signed-off-by: Coiby Xu <coxu@redhat.com>
>> ---
>>  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