[PATCH v3 14/14] KEYS: Introduce load_pgp_public_keyring()

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

Preload PGP keys from 'pubring.gpg', placed in certs/ of the kernel source
directory.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 certs/Kconfig               | 11 +++++++++++
 certs/Makefile              |  7 +++++++
 certs/system_certificates.S | 18 ++++++++++++++++++
 certs/system_keyring.c      | 23 +++++++++++++++++++++++
 4 files changed, 59 insertions(+)

diff --git a/certs/Kconfig b/certs/Kconfig
index 78307dc25559..9b7ece1e45fa 100644
--- a/certs/Kconfig
+++ b/certs/Kconfig
@@ -154,4 +154,15 @@ config SYSTEM_BLACKLIST_AUTH_UPDATE
 	  keyring.  The PKCS#7 signature of the description is set in the key
 	  payload.  Blacklist keys cannot be removed.
 
+config PGP_PRELOAD_PUBLIC_KEYS
+	bool "Preload PGP public keys"
+	depends on SYSTEM_TRUSTED_KEYRING
+	select PGP_PRELOAD
+	default n
+	help
+	  Load at boot time the PGP public keys from a reserved area (populated
+	  with the content of 'certs/pubring.gpg' provided at kernel build
+	  time), and add them to the built-in keyring. Invalid keys are ignored
+	  and the loading continues.
+
 endmenu
diff --git a/certs/Makefile b/certs/Makefile
index 1094e3860c2a..7a3d68441e09 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -31,6 +31,13 @@ $(obj)/system_certificates.o: $(obj)/x509_certificate_list
 $(obj)/x509_certificate_list: $(CONFIG_SYSTEM_TRUSTED_KEYS) $(obj)/extract-cert FORCE
 	$(call if_changed,extract_certs)
 
+ifdef CONFIG_PGP_PRELOAD_PUBLIC_KEYS
+ifeq ($(shell ls $(srctree)/certs/pubring.gpg 2> /dev/null), $(srctree)/certs/pubring.gpg)
+AFLAGS_system_certificates.o := -DHAVE_PUBRING_GPG
+$(obj)/system_certificates.o: $(srctree)/certs/pubring.gpg
+endif
+endif
+
 targets += x509_certificate_list
 
 # If module signing is requested, say by allyesconfig, but a key has not been
diff --git a/certs/system_certificates.S b/certs/system_certificates.S
index 003e25d4a17e..b3cbf0811e3f 100644
--- a/certs/system_certificates.S
+++ b/certs/system_certificates.S
@@ -44,3 +44,21 @@ module_cert_size:
 #else
 	.long __module_cert_end - __module_cert_start
 #endif
+
+	.align 8
+	.globl pgp_public_keys
+pgp_public_keys:
+__pgp_key_list_start:
+#ifdef HAVE_PUBRING_GPG
+	.incbin "certs/pubring.gpg"
+#endif
+__pgp_key_list_end:
+
+	.align 8
+	.globl pgp_public_keys_size
+pgp_public_keys_size:
+#ifdef CONFIG_64BIT
+	.quad __pgp_key_list_end - __pgp_key_list_start
+#else
+	.long __pgp_key_list_end - __pgp_key_list_start
+#endif
diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index f132773c6096..357d52d1d250 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c
@@ -32,6 +32,10 @@ static struct key *platform_trusted_keys;
 extern __initconst const u8 system_certificate_list[];
 extern __initconst const unsigned long system_certificate_list_size;
 extern __initconst const unsigned long module_cert_size;
+#ifdef CONFIG_PGP_PRELOAD_PUBLIC_KEYS
+extern __initconst const u8 pgp_public_keys[];
+extern __initconst const unsigned long pgp_public_keys_size;
+#endif
 
 /**
  * restrict_link_by_builtin_trusted - Restrict keyring addition by built-in CA
@@ -268,6 +272,15 @@ __init int load_module_cert(struct key *keyring)
 	if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG))
 		return 0;
 
+#ifdef CONFIG_PGP_PRELOAD_PUBLIC_KEYS
+	pr_notice("Load PGP public keys to keyring %s\n", keyring->description);
+
+	if (preload_pgp_keys(pgp_public_keys,
+			     pgp_public_keys_size,
+			     keyring) < 0)
+		pr_err("Can't load PGP public keys\n");
+#endif
+
 	pr_notice("Loading compiled-in module X.509 certificates\n");
 
 	return x509_load_certificate_list(system_certificate_list,
@@ -292,6 +305,16 @@ static __init int load_system_certificate_list(void)
 	size = system_certificate_list_size - module_cert_size;
 #endif
 
+#ifdef CONFIG_PGP_PRELOAD_PUBLIC_KEYS
+	pr_notice("Load PGP public keys to keyring %s\n",
+		  builtin_trusted_keys->description);
+
+	if (preload_pgp_keys(pgp_public_keys,
+			     pgp_public_keys_size,
+			     builtin_trusted_keys) < 0)
+		pr_err("Can't load PGP public keys\n");
+#endif
+
 	return x509_load_certificate_list(p, size, builtin_trusted_keys);
 }
 late_initcall(load_system_certificate_list);
-- 
2.34.1