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

[Coiby Xu]

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.

Cc: kexec at lists.infradead.org
Cc: keyrings at vger.kernel.org
Cc: linux-security-module at vger.kernel.org
Cc: stable at vger.kernel.org # 34d5960af253: kexec: clean up arch_kexec_kernel_verify_sig
Reviewed-by: Michal Suchanek <msuchanek at suse.de>
Signed-off-by: Coiby Xu <coxu at 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