From b39100bcea12b29d64c536ea5f4c57380dfcf056 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Tue, 1 Oct 2019 23:40:24 +0200
Subject: rsa: Allow to directly compile in rsa public keys

So far we relied on the U-Boot mkimage tool to generate us device tree
snippets containing rsa public keys which we then compiled into barebox.
Make this easier and allow to directly specify a filename or PKCS#11 URI
in Kconfig. With this we no longer need the U-Boot mkimage tool here and
no more external steps to prepare device tree snippets.

With this rsa public keys can be directly compiled as C structs into
barebox which is much more direct than putting it into the device tree.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 crypto/.gitignore |  2 ++
 crypto/Kconfig    | 19 +++++++++++++++++++
 crypto/Makefile   | 10 ++++++++++
 crypto/rsa.c      | 33 +++++++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+)
 create mode 100644 crypto/.gitignore

(limited to 'crypto')

diff --git a/crypto/.gitignore b/crypto/.gitignore
new file mode 100644
index 0000000000..92d8af3cf4
--- /dev/null
+++ b/crypto/.gitignore
@@ -0,0 +1,2 @@
+rsa-keys.h
+rsa-keys.h.tmp
diff --git a/crypto/Kconfig b/crypto/Kconfig
index c06d3c054e..7cc8aceacb 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -94,6 +94,25 @@ config CRYPTO_PBKDF2
 config CRYPTO_RSA
 	bool
 
+config CRYPTO_RSA_BUILTIN_KEYS
+	bool
+	default y if CRYPTO_RSA_KEY != ""
+
+config CRYPTO_RSA_KEY
+	depends on CRYPTO_RSA
+	string "RSA key to compile in"
+	help
+	  This option should be a filename of a PEM-formatted file containing
+	  X.509 certificates to be included into barebox. If the string starts
+	  with "pkcs11:" it is interpreted as a PKCS#11 URI rather than a file.
+
+config CRYPTO_RSA_KEY_NAME_HINT
+	depends on CRYPTO_RSA
+	string "FIT image key name hint"
+	help
+	  In FIT images keys are identified by a key name hint string. Provide
+	  the key name hint here.
+
 config CRYPTO_KEYSTORE
 	bool "Keystore"
 	help
diff --git a/crypto/Makefile b/crypto/Makefile
index d6fb74aad9..3f59de08f0 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -16,3 +16,13 @@ obj-$(CONFIG_DIGEST_SHA512_GENERIC)	+= sha4.o
 obj-$(CONFIG_CRYPTO_PBKDF2)	+= pbkdf2.o
 obj-$(CONFIG_CRYPTO_RSA)	+= rsa.o
 obj-$(CONFIG_CRYPTO_KEYSTORE)	+= keystore.o
+
+extra-$(CONFIG_CRYPTO_RSA_BUILTIN_KEYS) += rsa-keys.h
+
+ifdef CONFIG_CRYPTO_RSA_BUILTIN_KEYS
+
+$(obj)/rsa.o: $(obj)/rsa-keys.h
+$(eval $(call config_filename,CRYPTO_RSA_KEY))
+$(obj)/rsa-keys.h: FORCE
+	$(call cmd,rsa_keys,$(CONFIG_CRYPTO_RSA_KEY_NAME_HINT):$(CRYPTO_RSA_KEY_SRCPREFIX)$(CRYPTO_RSA_KEY_FILENAME))
+endif
diff --git a/crypto/rsa.c b/crypto/rsa.c
index 2e70c8127d..64241854c8 100644
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -438,3 +438,36 @@ void rsa_key_free(struct rsa_public_key *key)
 	free(key->rr);
 	free(key);
 }
+
+#ifdef CONFIG_CRYPTO_RSA_BUILTIN_KEYS
+#include "rsa-keys.h"
+
+extern const struct rsa_public_key * const __rsa_keys_start;
+extern const struct rsa_public_key * const __rsa_keys_end;
+
+struct rsa_public_key *rsa_get_key(const char *name)
+{
+	const struct rsa_public_key *key;
+	struct rsa_public_key *new;
+	const struct rsa_public_key * const *iter;
+
+	for (iter = &__rsa_keys_start; iter != &__rsa_keys_end; iter++) {
+		key = *iter;
+		if (!strcmp(name, key->key_name_hint))
+			goto found;
+	}
+
+	return ERR_PTR(-ENOENT);
+found:
+	new = xmemdup(key, sizeof(*key));
+	new->modulus = xmemdup(key->modulus, key->len * sizeof(uint32_t));
+	new->rr = xmemdup(key->rr, key->len  * sizeof(uint32_t));
+
+	return new;
+}
+#else
+struct rsa_public_key *rsa_get_key(const char *name)
+{
+	return ERR_PTR(-ENOENT);
+}
+#endif
-- 
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