[RFC PATCH v3 7/8] mkimage: add public key for image pre-load stage

[Philippe Reynes <philippe.reynes@softathome.com>]

This commit enhances mkimage to update the node
/image/pre-load/sig with the public key.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
---
 include/image.h    |  15 ++++++
 tools/fit_image.c  |   3 ++
 tools/image-host.c | 116 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 134 insertions(+)

diff --git a/include/image.h b/include/image.h
index 42fb01ab07..ac27e7acb2 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1019,6 +1019,21 @@ int fit_image_hash_get_value(const void *fit, int noffset, uint8_t **value,
 
 int fit_set_timestamp(void *fit, int noffset, time_t timestamp);
 
+/**
+ * fit_pre_load_data() - add public key to fdt blob
+ *
+ * @keydir:	Directory containing keys
+ * @keydest:	FDT blob to write public key
+ * @fit:	Pointer to the FIT format image header
+ *
+ * Adds public key to the node pre load.
+ *
+ * returns:
+ *	0, on success
+ *	< 0, on failure
+ */
+int fit_pre_load_data(const char *keydir, void *keydest, void *fit);
+
 int fit_cipher_data(const char *keydir, void *keydest, void *fit,
 		    const char *comment, int require_keys,
 		    const char *engine_id, const char *cmdname);
diff --git a/tools/fit_image.c b/tools/fit_image.c
index f4f372ba62..43ce41efbe 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -59,6 +59,9 @@ static int fit_add_file_data(struct image_tool_params *params, size_t size_inc,
 		ret = fit_set_timestamp(ptr, 0, time);
 	}
 
+	if (!ret)
+		ret = fit_pre_load_data(params->keydir, dest_blob, ptr);
+
 	if (!ret) {
 		ret = fit_cipher_data(params->keydir, dest_blob, ptr,
 				      params->comment,
diff --git a/tools/image-host.c b/tools/image-host.c
index a6b0a94420..20e59c14a9 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -14,6 +14,11 @@
 #include <image.h>
 #include <version.h>
 
+#include <openssl/pem.h>
+#include <openssl/evp.h>
+
+#define IMAGE_PRE_LOAD_PATH                             "/image/pre-load/sig"
+
 /**
  * fit_set_hash_value - set hash value in requested has node
  * @fit: pointer to the FIT format image header
@@ -1020,6 +1025,117 @@ static int fit_config_add_verification_data(const char *keydir,
 	return 0;
 }
 
+/*
+ * 0) open file (open)
+ * 1) read certificate (PEM_read_X509)
+ * 2) get public key (X509_get_pubkey)
+ * 3) provide der format (d2i_RSAPublicKey)
+ */
+static int read_pub_key(const char *keydir, const void *name,
+			unsigned char **pubkey, int *pubkey_len)
+{
+	char path[1024];
+	EVP_PKEY *key = NULL;
+	X509 *cert;
+	FILE *f;
+	int ret;
+
+	memset(path, 0, 1024);
+	snprintf(path, sizeof(path), "%s/%s.crt", keydir, (char *)name);
+
+	/* Open certificate file */
+	f = fopen(path, "r");
+	if (!f) {
+		fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
+			path, strerror(errno));
+		return -EACCES;
+	}
+
+	/* Read the certificate */
+	cert = NULL;
+	if (!PEM_read_X509(f, &cert, NULL, NULL)) {
+		printf("Couldn't read certificate");
+		ret = -EINVAL;
+		goto err_cert;
+	}
+
+	/* Get the public key from the certificate. */
+	key = X509_get_pubkey(cert);
+	if (!key) {
+		printf("Couldn't read public key\n");
+		ret = -EINVAL;
+		goto err_pubkey;
+	}
+
+	/* Get DER form */
+	ret = i2d_PublicKey(key, pubkey);
+	if (ret < 0) {
+		printf("Couldn't get DER form\n");
+		ret = -EINVAL;
+		goto err_pubkey;
+	}
+
+	*pubkey_len = ret;
+	ret = 0;
+
+err_pubkey:
+	X509_free(cert);
+err_cert:
+	fclose(f);
+	return ret;
+}
+
+int fit_pre_load_data(const char *keydir, void *keydest, void *fit)
+{
+	int pre_load_noffset;
+	const void *header_size, *algo_name;
+	const void *key_name;
+	unsigned char *pubkey = NULL;
+	int ret, pubkey_len;
+
+	if (!keydir || !keydest || !fit)
+		return 0;
+
+	/* Search node pre-load sig */
+	pre_load_noffset = fdt_path_offset(keydest, IMAGE_PRE_LOAD_PATH);
+	if (pre_load_noffset < 0) {
+		ret = 0;
+		goto out;
+	}
+
+	header_size  = fdt_getprop(keydest, pre_load_noffset, "header-size", NULL);
+	algo_name    = fdt_getprop(keydest, pre_load_noffset, "algo-name", NULL);
+	key_name     = fdt_getprop(keydest, pre_load_noffset, "key-name", NULL);
+
+	/* Check that all mandatory properties are present */
+	if (!header_size || !algo_name || !key_name) {
+		if (!header_size)
+			printf("The property header-size is missing in the node %s\n",
+			       IMAGE_PRE_LOAD_PATH);
+		if (!algo_name)
+			printf("The property algo-name is missing in the node %s\n",
+			       IMAGE_PRE_LOAD_PATH);
+		if (!key_name)
+			printf("The property key-name is missing in the node %s\n",
+			       IMAGE_PRE_LOAD_PATH);
+		ret = -ENODATA;
+		goto out;
+	}
+
+	/* Read public key */
+	ret = read_pub_key(keydir, key_name, &pubkey, &pubkey_len);
+	if (ret < 0)
+		goto out;
+
+	/* Add the public key to the device tree */
+	ret = fdt_setprop(keydest, pre_load_noffset, "public-key", pubkey, pubkey_len);
+	if (ret)
+		printf("Can't set public-key in node %s\n", IMAGE_PRE_LOAD_PATH);
+
+ out:
+	return ret;
+}
+
 int fit_cipher_data(const char *keydir, void *keydest, void *fit,
 		    const char *comment, int require_keys,
 		    const char *engine_id, const char *cmdname)
-- 
2.17.1