lib: rsa: decouple rsa from FIT image verification

Introduce new configuration, CONFIG_RSA_VERIFY which will decouple building
RSA functions from FIT verification and allow for adding a RSA-based
signature verification for other file formats, in particular PE file
for UEFI secure boot.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

3 files changed, 58 insertions, 32 deletions

diff --git a/lib/rsa/Kconfig b/lib/rsa/Kconfig
index 2b33f32..18a075c 100644
--- a/lib/rsa/Kconfig
+++ b/lib/rsa/Kconfig
@@ -18,6 +18,16 @@ if RSA
 config SPL_RSA
 	bool "Use RSA Library within SPL"
 
+config SPL_RSA_VERIFY
+	bool
+	help
+	  Add RSA signature verification support in SPL.
+
+config RSA_VERIFY
+	bool
+	help
+	  Add RSA signature verification support.
+
 config RSA_SOFTWARE_EXP
 	bool "Enable driver for RSA Modular Exponentiation in software"
 	depends on DM
diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile
index a51c6e1..c073051 100644
--- a/lib/rsa/Makefile
+++ b/lib/rsa/Makefile
@@ -5,5 +5,5 @@
 # (C) Copyright 2000-2007
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-obj-$(CONFIG_$(SPL_)FIT_SIGNATURE) += rsa-verify.o rsa-checksum.o
+obj-$(CONFIG_$(SPL_)RSA_VERIFY) += rsa-verify.o rsa-checksum.o
 obj-$(CONFIG_RSA_SOFTWARE_EXP) += rsa-mod-exp.o
diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
index 326a5e4..3dd30c8 100644
--- a/lib/rsa/rsa-verify.c
+++ b/lib/rsa/rsa-verify.c
@@ -271,6 +271,7 @@ out:
 }
 #endif
 
+#if CONFIG_IS_ENABLED(FIT_SIGNATURE)
 /**
  * rsa_verify_key() - Verify a signature against some data using RSA Key
  *
@@ -342,7 +343,9 @@ static int rsa_verify_key(struct image_sign_info *info,
 
 	return 0;
 }
+#endif
 
+#if CONFIG_IS_ENABLED(FIT_SIGNATURE)
 /**
  * rsa_verify_with_keynode() - Verify a signature against some data using
  * information in node with prperties of RSA Key like modulus, exponent etc.
@@ -396,18 +399,22 @@ static int rsa_verify_with_keynode(struct image_sign_info *info,
 
 	return ret;
 }
+#else
+static int rsa_verify_with_keynode(struct image_sign_info *info,
+				   const void *hash, uint8_t *sig,
+				   uint sig_len, int node)
+{
+	return -EACCES;
+}
+#endif
 
 int rsa_verify(struct image_sign_info *info,
 	       const struct image_region region[], int region_count,
 	       uint8_t *sig, uint sig_len)
 {
-	const void *blob = info->fdt_blob;
 	/* Reserve memory for maximum checksum-length */
 	uint8_t hash[info->crypto->key_len];
-	int ndepth, noffset;
-	int sig_node, node;
-	char name[100];
-	int ret;
+	int ret = -EACCES;
 
 	/*
 	 * Verify that the checksum-length does not exceed the
@@ -420,12 +427,6 @@ int rsa_verify(struct image_sign_info *info,
 		return -EINVAL;
 	}
 
-	sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
-	if (sig_node < 0) {
-		debug("%s: No signature node found\n", __func__);
-		return -ENOENT;
-	}
-
 	/* Calculate checksum with checksum-algorithm */
 	ret = info->checksum->calculate(info->checksum->name,
 					region, region_count, hash);
@@ -434,29 +435,44 @@ int rsa_verify(struct image_sign_info *info,
 		return -EINVAL;
 	}
 
-	/* See if we must use a particular key */
-	if (info->required_keynode != -1) {
-		ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
-			info->required_keynode);
-		return ret;
-	}
+	if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) {
+		const void *blob = info->fdt_blob;
+		int ndepth, noffset;
+		int sig_node, node;
+		char name[100];
 
-	/* Look for a key that matches our hint */
-	snprintf(name, sizeof(name), "key-%s", info->keyname);
-	node = fdt_subnode_offset(blob, sig_node, name);
-	ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
-	if (!ret)
-		return ret;
+		sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
+		if (sig_node < 0) {
+			debug("%s: No signature node found\n", __func__);
+			return -ENOENT;
+		}
 
-	/* No luck, so try each of the keys in turn */
-	for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node, &ndepth);
-			(noffset >= 0) && (ndepth > 0);
-			noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
-		if (ndepth == 1 && noffset != node) {
+		/* See if we must use a particular key */
+		if (info->required_keynode != -1) {
 			ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
-						      noffset);
-			if (!ret)
-				break;
+						      info->required_keynode);
+			return ret;
+		}
+
+		/* Look for a key that matches our hint */
+		snprintf(name, sizeof(name), "key-%s", info->keyname);
+		node = fdt_subnode_offset(blob, sig_node, name);
+		ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
+		if (!ret)
+			return ret;
+
+		/* No luck, so try each of the keys in turn */
+		for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node,
+							 &ndepth);
+		     (noffset >= 0) && (ndepth > 0);
+		     noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
+			if (ndepth == 1 && noffset != node) {
+				ret = rsa_verify_with_keynode(info, hash,
+							      sig, sig_len,
+							      noffset);
+				if (!ret)
+					break;
+			}
 		}
 	}