certs: Break circular dependency when selftest is modular

The modular build fails because the self-test code depends on pkcs7
which in turn depends on x509 which contains the self-test.

Split the self-test out into its own module to break the cycle.

Fixes: 3cde3174eb91 ("certs: Add FIPS selftests")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

On Mon Oct 16, 2023 at 8:21 AM EEST, Herbert Xu wrote:
> The modular build fails because the self-test code depends on pkcs7
> which in turn depends on x509 which contains the self-test.
>
> Split the self-test out into its own module to break the cycle.
>
> Fixes: 3cde3174eb91 ("certs: Add FIPS selftests")
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
> diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
> index 1ef3b46d6f6e..59ec726b7c77 100644
> --- a/crypto/asymmetric_keys/Kconfig
> +++ b/crypto/asymmetric_keys/Kconfig
> @@ -76,7 +76,7 @@ config SIGNED_PE_FILE_VERIFICATION
>  	  signed PE binary.
>  
>  config FIPS_SIGNATURE_SELFTEST
> -	bool "Run FIPS selftests on the X.509+PKCS7 signature verification"
> +	tristate "Run FIPS selftests on the X.509+PKCS7 signature verification"
>  	help
>  	  This option causes some selftests to be run on the signature
>  	  verification code, using some built in data.  This is required
> @@ -84,5 +84,6 @@ config FIPS_SIGNATURE_SELFTEST
>  	depends on KEYS
>  	depends on ASYMMETRIC_KEY_TYPE
>  	depends on PKCS7_MESSAGE_PARSER=X509_CERTIFICATE_PARSER
> +	depends on X509_CERTIFICATE_PARSER
>  
>  endif # ASYMMETRIC_KEY_TYPE
> diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
> index 0d1fa1b692c6..1a273d6df3eb 100644
> --- a/crypto/asymmetric_keys/Makefile
> +++ b/crypto/asymmetric_keys/Makefile
> @@ -22,7 +22,8 @@ x509_key_parser-y := \
>  	x509_cert_parser.o \
>  	x509_loader.o \
>  	x509_public_key.o
> -x509_key_parser-$(CONFIG_FIPS_SIGNATURE_SELFTEST) += selftest.o
> +obj-$(CONFIG_FIPS_SIGNATURE_SELFTEST) += x509_selftest.o
> +x509_selftest-y += selftest.o
>  
>  $(obj)/x509_cert_parser.o: \
>  	$(obj)/x509.asn1.h \
> diff --git a/crypto/asymmetric_keys/selftest.c b/crypto/asymmetric_keys/selftest.c
> index fa0bf7f24284..c50da7ef90ae 100644
> --- a/crypto/asymmetric_keys/selftest.c
> +++ b/crypto/asymmetric_keys/selftest.c
> @@ -4,10 +4,11 @@
>   * Written by David Howells (dhowells@redhat.com)
>   */
>  
> -#include <linux/kernel.h>
> -#include <linux/cred.h>
> -#include <linux/key.h>
>  #include <crypto/pkcs7.h>
> +#include <linux/cred.h>
> +#include <linux/kernel.h>
> +#include <linux/key.h>
> +#include <linux/module.h>
>  #include "x509_parser.h"
>  
>  struct certs_test {
> @@ -175,7 +176,7 @@ static const struct certs_test certs_tests[] __initconst = {
>  	TEST(certs_selftest_1_data, certs_selftest_1_pkcs7),
>  };
>  
> -int __init fips_signature_selftest(void)
> +static int __init fips_signature_selftest(void)
>  {
>  	struct key *keyring;
>  	int ret, i;
> @@ -222,3 +223,9 @@ int __init fips_signature_selftest(void)
>  	key_put(keyring);
>  	return 0;
>  }
> +
> +late_initcall(fips_signature_selftest);
> +
> +MODULE_DESCRIPTION("X.509 self tests");
> +MODULE_AUTHOR("Red Hat, Inc.");

Not anything related to this patch per se but I'm wondering how useful
MODULE_AUTHOR() field is in the modern times... It can sometimes point
out to a person who has long gone from working with kernel and generally
is misleading. Git sort of provides the field in better granularity.

> +MODULE_LICENSE("GPL");
> diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
> index a299c9c56f40..97a886cbe01c 100644
> --- a/crypto/asymmetric_keys/x509_parser.h
> +++ b/crypto/asymmetric_keys/x509_parser.h
> @@ -40,15 +40,6 @@ struct x509_certificate {
>  	bool		blacklisted;
>  };
>  
> -/*
> - * selftest.c
> - */
> -#ifdef CONFIG_FIPS_SIGNATURE_SELFTEST
> -extern int __init fips_signature_selftest(void);
> -#else
> -static inline int fips_signature_selftest(void) { return 0; }
> -#endif
> -
>  /*
>   * x509_cert_parser.c
>   */
> diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
> index 7c71db3ac23d..6a4f00be22fc 100644
> --- a/crypto/asymmetric_keys/x509_public_key.c
> +++ b/crypto/asymmetric_keys/x509_public_key.c
> @@ -262,15 +262,9 @@ static struct asymmetric_key_parser x509_key_parser = {
>  /*
>   * Module stuff
>   */
> -extern int __init certs_selftest(void);
>  static int __init x509_key_init(void)
>  {
> -	int ret;
> -
> -	ret = register_asymmetric_key_parser(&x509_key_parser);
> -	if (ret < 0)
> -		return ret;
> -	return fips_signature_selftest();
> +	return register_asymmetric_key_parser(&x509_key_parser);
>  }
>  
>  static void __exit x509_key_exit(void)

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

David, are you going to pick this?

BR, Jarkko