image: Support signing of images

Add support for signing images using a new signature node. The process
is handled by fdt_add_verification_data() which now takes parameters to
provide the keys and related information.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/image-fit.c

@@ -234,42 +234,45 @@ void fit_print_contents(const void *fit)
  * @fit: pointer to the FIT format image header
  * @noffset: offset of the hash node
  * @p: pointer to prefix string
+ * @type: Type of information to print ("hash" or "sign")
  *
  * fit_image_print_data() lists properies for the processed hash node
  *
+ * This function avoid using puts() since it prints a newline on the host
+ * but does not in U-Boot.
+ *
  * returns:
  *     no returned results
  */
-static void fit_image_print_data(const void *fit, int noffset, const char *p)
+static void fit_image_print_data(const void *fit, int noffset, const char *p,
+				 const char *type)
 {
-	char *algo;
+	const char *keyname;
 	uint8_t *value;
 	int value_len;
-	int i, ret;
-
-	/*
-	 * Check subnode name, must be equal to "hash".
-	 * Multiple hash nodes require unique unit node
-	 * names, e.g. hash@1, hash@2, etc.
-	 */
-	if (strncmp(fit_get_name(fit, noffset, NULL),
-		    FIT_HASH_NODENAME,
-		    strlen(FIT_HASH_NODENAME)) != 0)
-		return;
+	char *algo;
+	int required;
+	int ret, i;
 
-	debug("%s  Hash node:    '%s'\n", p,
+	debug("%s  %s node:    '%s'\n", p, type,
 	      fit_get_name(fit, noffset, NULL));
-
-	printf("%s  Hash algo:    ", p);
+	printf("%s  %s algo:    ", p, type);
 	if (fit_image_hash_get_algo(fit, noffset, &algo)) {
 		printf("invalid/unsupported\n");
 		return;
 	}
-	printf("%s\n", algo);
+	printf("%s", algo);
+	keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	required = fdt_getprop(fit, noffset, "required", NULL) != NULL;
+	if (keyname)
+		printf(":%s", keyname);
+	if (required)
+		printf(" (required)");
+	printf("\n");
 
 	ret = fit_image_hash_get_value(fit, noffset, &value,
 					&value_len);
-	printf("%s  Hash value:   ", p);
+	printf("%s  %s value:   ", p, type);
 	if (ret) {
 		printf("unavailable\n");
 	} else {
@@ -278,7 +281,18 @@ static void fit_image_print_data(const void *fit, int noffset, const char *p)
 		printf("\n");
 	}
 
-	debug("%s  Hash len:     %d\n", p, value_len);
+	debug("%s  %s len:     %d\n", p, type, value_len);
+
+	/* Signatures have a time stamp */
+	if (IMAGE_ENABLE_TIMESTAMP && keyname) {
+		time_t timestamp;
+
+		printf("%s  Timestamp:    ", p);
+		if (fit_get_timestamp(fit, noffset, &timestamp))
+			printf("unavailable\n");
+		else
+			genimg_print_time(timestamp);
+	}
 }
 
 /**
@@ -303,8 +317,12 @@ static void fit_image_print_verification_data(const void *fit, int noffset,
 	 * names, e.g. hash@1, hash@2, signature@1, signature@2, etc.
 	 */
 	name = fit_get_name(fit, noffset, NULL);
-	if (!strncmp(name, FIT_HASH_NODENAME, strlen(FIT_HASH_NODENAME)))
-		fit_image_print_data(fit, noffset, p);
+	if (!strncmp(name, FIT_HASH_NODENAME, strlen(FIT_HASH_NODENAME))) {
+		fit_image_print_data(fit, noffset, p, "Hash");
+	} else if (!strncmp(name, FIT_SIG_NODENAME,
+				strlen(FIT_SIG_NODENAME))) {
+		fit_image_print_data(fit, noffset, p, "Sign");
+	}
 }
 
 /**
@@ -944,13 +962,23 @@ int fit_image_verify(const void *fit, int image_noffset)
 {
 	const void	*data;
 	size_t		size;
-	int		noffset;
+	int		noffset = 0;
 	char		*err_msg = "";
+	int verify_all = 1;
+	int ret;
 
 	/* Get image data and data length */
 	if (fit_image_get_data(fit, image_noffset, &data, &size)) {
 		err_msg = "Can't get image data/size";
-		return 0;
+		goto error;
+	}
+
+	/* Verify all required signatures */
+	if (IMAGE_ENABLE_VERIFY &&
+	    fit_image_verify_required_sigs(fit, image_noffset, data, size,
+					   gd_fdt_blob(), &verify_all)) {
+		err_msg = "Unable to verify required signature";
+		goto error;
 	}
 
 	/* Process all hash subnodes of the component image node */
@@ -970,6 +998,15 @@ int fit_image_verify(const void *fit, int image_noffset)
 						 &err_msg))
 				goto error;
 			puts("+ ");
+		} else if (IMAGE_ENABLE_VERIFY && verify_all &&
+				!strncmp(name, FIT_SIG_NODENAME,
+					strlen(FIT_SIG_NODENAME))) {
+			ret = fit_image_check_sig(fit, noffset, data,
+							size, -1, &err_msg);
+			if (ret)
+				puts("- ");
+			else
+				puts("+ ");
 		}
 	}
 

common/image-sig.c

@@ -22,6 +22,8 @@
 #include <time.h>
 #else
 #include <common.h>
+#include <malloc.h>
+DECLARE_GLOBAL_DATA_PTR;
 #endif /* !USE_HOSTCC*/
 #include <errno.h>
 #include <image.h>
@@ -40,3 +42,145 @@ struct image_sig_algo *image_get_sig_algo(const char *name)
 
 	return NULL;
 }
+
+static int fit_image_setup_verify(struct image_sign_info *info,
+		const void *fit, int noffset, int required_keynode,
+		char **err_msgp)
+{
+	char *algo_name;
+
+	if (fit_image_hash_get_algo(fit, noffset, &algo_name)) {
+		*err_msgp = "Can't get hash algo property";
+		return -1;
+	}
+	memset(info, '\0', sizeof(*info));
+	info->keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	info->fit = (void *)fit;
+	info->node_offset = noffset;
+	info->algo = image_get_sig_algo(algo_name);
+	info->fdt_blob = gd_fdt_blob();
+	info->required_keynode = required_keynode;
+	printf("%s:%s", algo_name, info->keyname);
+
+	if (!info->algo) {
+		*err_msgp = "Unknown signature algorithm";
+		return -1;
+	}
+
+	return 0;
+}
+
+int fit_image_check_sig(const void *fit, int noffset, const void *data,
+		size_t size, int required_keynode, char **err_msgp)
+{
+	struct image_sign_info info;
+	struct image_region region;
+	uint8_t *fit_value;
+	int fit_value_len;
+
+	*err_msgp = NULL;
+	if (fit_image_setup_verify(&info, fit, noffset, required_keynode,
+				   err_msgp))
+		return -1;
+
+	if (fit_image_hash_get_value(fit, noffset, &fit_value,
+				     &fit_value_len)) {
+		*err_msgp = "Can't get hash value property";
+		return -1;
+	}
+
+	region.data = data;
+	region.size = size;
+
+	if (info.algo->verify(&info, &region, 1, fit_value, fit_value_len)) {
+		*err_msgp = "Verification failed";
+		return -1;
+	}
+
+	return 0;
+}
+
+static int fit_image_verify_sig(const void *fit, int image_noffset,
+		const char *data, size_t size, const void *sig_blob,
+		int sig_offset)
+{
+	int noffset;
+	char *err_msg = "";
+	int verified = 0;
+	int ret;
+
+	/* Process all hash subnodes of the component image node */
+	for (noffset = fdt_first_subnode(fit, image_noffset);
+	     noffset >= 0;
+	     noffset = fdt_next_subnode(fit, noffset)) {
+		const char *name = fit_get_name(fit, noffset, NULL);
+
+		if (!strncmp(name, FIT_SIG_NODENAME,
+			     strlen(FIT_SIG_NODENAME))) {
+			ret = fit_image_check_sig(fit, noffset, data,
+							size, -1, &err_msg);
+			if (ret) {
+				puts("- ");
+			} else {
+				puts("+ ");
+				verified = 1;
+				break;
+			}
+		}
+	}
+
+	if (noffset == -FDT_ERR_TRUNCATED || noffset == -FDT_ERR_BADSTRUCTURE) {
+		err_msg = "Corrupted or truncated tree";
+		goto error;
+	}
+
+	return verified ? 0 : -EPERM;
+
+error:
+	printf(" error!\n%s for '%s' hash node in '%s' image node\n",
+	       err_msg, fit_get_name(fit, noffset, NULL),
+	       fit_get_name(fit, image_noffset, NULL));
+	return -1;
+}
+
+int fit_image_verify_required_sigs(const void *fit, int image_noffset,
+		const char *data, size_t size, const void *sig_blob,
+		int *no_sigsp)
+{
+	int verify_count = 0;
+	int noffset;
+	int sig_node;
+
+	/* Work out what we need to verify */
+	*no_sigsp = 1;
+	sig_node = fdt_subnode_offset(sig_blob, 0, FIT_SIG_NODENAME);
+	if (sig_node < 0) {
+		debug("%s: No signature node found: %s\n", __func__,
+		      fdt_strerror(sig_node));
+		return 0;
+	}
+
+	for (noffset = fdt_first_subnode(sig_blob, sig_node);
+	     noffset >= 0;
+	     noffset = fdt_next_subnode(sig_blob, noffset)) {
+		const char *required;
+		int ret;
+
+		required = fdt_getprop(sig_blob, noffset, "required", NULL);
+		if (!required || strcmp(required, "image"))
+			continue;
+		ret = fit_image_verify_sig(fit, image_noffset, data, size,
+					sig_blob, noffset);
+		if (ret) {
+			printf("Failed to verify required signature '%s'\n",
+			       fit_get_name(sig_blob, noffset, NULL));
+			return ret;
+		}
+		verify_count++;
+	}
+
+	if (verify_count)
+		*no_sigsp = 0;
+
+	return 0;
+}

doc/uImage.FIT/sign-images.its

@@ -0,0 +1,42 @@
+/dts-v1/;
+
+/ {
+	description = "Chrome OS kernel image with one or more FDT blobs";
+	#address-cells = <1>;
+
+	images {
+		kernel@1 {
+			data = /incbin/("test-kernel.bin");
+			type = "kernel_noload";
+			arch = "sandbox";
+			os = "linux";
+			compression = "none";
+			load = <0x4>;
+			entry = <0x8>;
+			kernel-version = <1>;
+			signature@1 {
+				algo = "sha1,rsa2048";
+				key-name-hint = "dev";
+			};
+		};
+		fdt@1 {
+			description = "snow";
+			data = /incbin/("sandbox-kernel.dtb");
+			type = "flat_dt";
+			arch = "sandbox";
+			compression = "none";
+			fdt-version = <1>;
+			signature@1 {
+				algo = "sha1,rsa2048";
+				key-name-hint = "dev";
+			};
+		};
+	};
+	configurations {
+		default = "conf@1";
+		conf@1 {
+			kernel = "kernel@1";
+			fdt = "fdt@1";
+		};
+	};
+};

include/image.h

@@ -766,12 +766,26 @@ 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_add_verification_data() - Calculate and add hashes to FIT
+ * fit_add_verification_data() - add verification data to FIT image nodes
  *
- * @fit:	Fit image to process
- * @return 0 if ok, <0 for error
+ * @keydir:	Directory containing keys
+ * @kwydest:	FDT blob to write public key information to
+ * @fit:	Pointer to the FIT format image header
+ * @comment:	Comment to add to signature nodes
+ * @require_keys: Mark all keys as 'required'
+ *
+ * Adds hash values for all component images in the FIT blob.
+ * Hashes are calculated for all component images which have hash subnodes
+ * with algorithm property set to one of the supported hash algorithms.
+ *
+ * Also add signatures if signature nodes are present.
+ *
+ * returns
+ *     0, on success
+ *     libfdt error code, on failure
  */
-int fit_add_verification_data(void *fit);
+int fit_add_verification_data(const char *keydir, void *keydest, void *fit,
+			      const char *comment, int require_keys);
 
 int fit_image_verify(const void *fit, int noffset);
 int fit_config_verify(const void *fit, int conf_noffset);
@@ -914,6 +928,43 @@ struct image_sig_algo {
  */
 struct image_sig_algo *image_get_sig_algo(const char *name);
 
+/**
+ * fit_image_verify_required_sigs() - Verify signatures marked as 'required'
+ *
+ * @fit:		FIT to check
+ * @image_noffset:	Offset of image node to check
+ * @data:		Image data to check
+ * @size:		Size of image data
+ * @sig_blob:		FDT containing public keys
+ * @no_sigsp:		Returns 1 if no signatures were required, and
+ *			therefore nothing was checked. The caller may wish
+ *			to fall back to other mechanisms, or refuse to
+ *			boot.
+ * @return 0 if all verified ok, <0 on error
+ */
+int fit_image_verify_required_sigs(const void *fit, int image_noffset,
+		const char *data, size_t size, const void *sig_blob,
+		int *no_sigsp);
+
+/**
+ * fit_image_check_sig() - Check a single image signature node
+ *
+ * @fit:		FIT to check
+ * @noffset:		Offset of signature node to check
+ * @data:		Image data to check
+ * @size:		Size of image data
+ * @required_keynode:	Offset in the control FDT of the required key node,
+ *			if any. If this is given, then the image wil not
+ *			pass verification unless that key is used. If this is
+ *			-1 then any signature will do.
+ * @err_msgp:		In the event of an error, this will be pointed to a
+ *			help error string to display to the user.
+ * @return 0 if all verified ok, <0 on error
+ */
+int fit_image_check_sig(const void *fit, int noffset, const void *data,
+		size_t size, int required_keynode, char **err_msgp);
+
+
 static inline int fit_image_check_target_arch(const void *fdt, int node)
 {
 	return fit_image_check_arch(fdt, node, IH_ARCH_DEFAULT);

tools/fit_image.c

@@ -137,7 +137,7 @@ static int fit_handle_file (struct mkimage_params *params)
 		goto err_mmap;
 
 	/* set hashes for images in the blob */
-	if (fit_add_verification_data(ptr)) {
+	if (fit_add_verification_data(NULL, NULL, ptr, NULL, 0)) {
 		fprintf (stderr, "%s Can't add hashes to FIT blob",
 				params->cmdname);
 		goto err_add_hashes;

tools/image-host.c

@@ -26,12 +26,8 @@
  */
 
 #include "mkimage.h"
-#include <bootstage.h>
 #include <image.h>
-#include <sha1.h>
-#include <time.h>
-#include <u-boot/crc.h>
-#include <u-boot/md5.h>
+#include <version.h>
 
 /**
  * fit_set_hash_value - set hash value in requested has node
@@ -108,9 +104,165 @@ static int fit_image_process_hash(void *fit, const char *image_name,
 }
 
 /**
- * fit_image_add_verification_data() - calculate/set hash data for image node
+ * fit_image_write_sig() - write the signature to a FIT
  *
- * This adds hash values for a component image node.
+ * This writes the signature and signer data to the FIT.
+ *
+ * @fit: pointer to the FIT format image header
+ * @noffset: hash node offset
+ * @value: signature value to be set
+ * @value_len: signature value length
+ * @comment: Text comment to write (NULL for none)
+ *
+ * returns
+ *     0, on success
+ *     -FDT_ERR_..., on failure
+ */
+static int fit_image_write_sig(void *fit, int noffset, uint8_t *value,
+		int value_len, const char *comment, const char *region_prop,
+		int region_proplen)
+{
+	int string_size;
+	int ret;
+
+	/*
+	 * Get the current string size, before we update the FIT and add
+	 * more
+	 */
+	string_size = fdt_size_dt_strings(fit);
+
+	ret = fdt_setprop(fit, noffset, FIT_VALUE_PROP, value, value_len);
+	if (!ret) {
+		ret = fdt_setprop_string(fit, noffset, "signer-name",
+					 "mkimage");
+	}
+	if (!ret) {
+		ret = fdt_setprop_string(fit, noffset, "signer-version",
+				  PLAIN_VERSION);
+	}
+	if (comment && !ret)
+		ret = fdt_setprop_string(fit, noffset, "comment", comment);
+	if (!ret)
+		ret = fit_set_timestamp(fit, noffset, time(NULL));
+	if (region_prop && !ret) {
+		uint32_t strdata[2];
+
+		ret = fdt_setprop(fit, noffset, "hashed-nodes",
+				   region_prop, region_proplen);
+		strdata[0] = 0;
+		strdata[1] = cpu_to_fdt32(string_size);
+		if (!ret) {
+			ret = fdt_setprop(fit, noffset, "hashed-strings",
+					  strdata, sizeof(strdata));
+		}
+	}
+
+	return ret;
+}
+
+static int fit_image_setup_sig(struct image_sign_info *info,
+		const char *keydir, void *fit, const char *image_name,
+		int noffset, const char *require_keys)
+{
+	const char *node_name;
+	char *algo_name;
+
+	node_name = fit_get_name(fit, noffset, NULL);
+	if (fit_image_hash_get_algo(fit, noffset, &algo_name)) {
+		printf("Can't get algo property for '%s' signature node in '%s' image node\n",
+		       node_name, image_name);
+		return -1;
+	}
+
+	memset(info, '\0', sizeof(*info));
+	info->keydir = keydir;
+	info->keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+	info->fit = fit;
+	info->node_offset = noffset;
+	info->algo = image_get_sig_algo(algo_name);
+	info->require_keys = require_keys;
+	if (!info->algo) {
+		printf("Unsupported signature algorithm (%s) for '%s' signature node in '%s' image node\n",
+		       algo_name, node_name, image_name);
+		return -1;
+	}
+
+	return 0;
+}
+
+/**
+ * fit_image_process_sig- Process a single subnode of the images/ node
+ *
+ * Check each subnode and process accordingly. For signature nodes we
+ * generate a signed hash of the supplised data and store it in the node.
+ *
+ * @keydir:	Directory containing keys to use for signing
+ * @keydest:	Destination FDT blob to write public keys into
+ * @fit:	pointer to the FIT format image header
+ * @image_name:	name of image being processes (used to display errors)
+ * @noffset:	subnode offset
+ * @data:	data to process
+ * @size:	size of data in bytes
+ * @comment:	Comment to add to signature nodes
+ * @require_keys: Mark all keys as 'required'
+ * @return 0 if ok, -1 on error
+ */
+static int fit_image_process_sig(const char *keydir, void *keydest,
+		void *fit, const char *image_name,
+		int noffset, const void *data, size_t size,
+		const char *comment, int require_keys)
+{
+	struct image_sign_info info;
+	struct image_region region;
+	const char *node_name;
+	uint8_t *value;
+	uint value_len;
+	int ret;
+
+	if (fit_image_setup_sig(&info, keydir, fit, image_name, noffset,
+				require_keys ? "image" : NULL))
+		return -1;
+
+	node_name = fit_get_name(fit, noffset, NULL);
+	region.data = data;
+	region.size = size;
+	ret = info.algo->sign(&info, &region, 1, &value, &value_len);
+	if (ret) {
+		printf("Failed to sign '%s' signature node in '%s' image node: %d\n",
+		       node_name, image_name, ret);
+
+		/* We allow keys to be missing */
+		if (ret == -ENOENT)
+			return 0;
+		return -1;
+	}
+
+	ret = fit_image_write_sig(fit, noffset, value, value_len, comment,
+			NULL, 0);
+	if (ret) {
+		printf("Can't write signature for '%s' signature node in '%s' image node: %s\n",
+		       node_name, image_name, fdt_strerror(ret));
+		return -1;
+	}
+	free(value);
+
+	/* Get keyname again, as FDT has changed and invalidated our pointer */
+	info.keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+
+	/* Write the public key into the supplied FDT file */
+	if (keydest && info.algo->add_verify_data(&info, keydest)) {
+		printf("Failed to add verification data for '%s' signature node in '%s' image node\n",
+		       node_name, image_name);
+		return -1;
+	}
+
+	return 0;
+}
+
+/**
+ * fit_image_add_verification_data() - calculate/set verig. data for image node
+ *
+ * This adds hash and signature values for an component image node.
  *
  * All existing hash subnodes are checked, if algorithm property is set to
  * one of the supported hash algorithms, hash value is computed and
@@ -133,11 +285,17 @@ static int fit_image_process_hash(void *fit, const char *image_name,
  *
  * For signature details, please see doc/uImage.FIT/signature.txt
  *
+ * @keydir	Directory containing *.key and *.crt files (or NULL)
+ * @keydest	FDT Blob to write public keys into (NULL if none)
  * @fit:	Pointer to the FIT format image header
  * @image_noffset: Requested component image node
+ * @comment:	Comment to add to signature nodes
+ * @require_keys: Mark all keys as 'required'
  * @return: 0 on success, <0 on failure
  */
-int fit_image_add_verification_data(void *fit, int image_noffset)
+int fit_image_add_verification_data(const char *keydir, void *keydest,
+		void *fit, int image_noffset, const char *comment,
+		int require_keys)
 {
 	const char *image_name;
 	const void *data;
@@ -169,6 +327,12 @@ int fit_image_add_verification_data(void *fit, int image_noffset)
 			     strlen(FIT_HASH_NODENAME))) {
 			ret = fit_image_process_hash(fit, image_name, noffset,
 						data, size);
+		} else if (IMAGE_ENABLE_SIGN && keydir &&
+			   !strncmp(node_name, FIT_SIG_NODENAME,
+				strlen(FIT_SIG_NODENAME))) {
+			ret = fit_image_process_sig(keydir, keydest,
+				fit, image_name, noffset, data, size,
+				comment, require_keys);
 		}
 		if (ret)
 			return -1;
@@ -177,7 +341,8 @@ int fit_image_add_verification_data(void *fit, int image_noffset)
 	return 0;
 }
 
-int fit_add_verification_data(void *fit)
+int fit_add_verification_data(const char *keydir, void *keydest, void *fit,
+			      const char *comment, int require_keys)
 {
 	int images_noffset;
 	int noffset;
@@ -199,7 +364,8 @@ int fit_add_verification_data(void *fit)
 		 * Direct child node of the images parent node,
 		 * i.e. component image node.
 		 */
-		ret = fit_image_add_verification_data(fit, noffset);
+		ret = fit_image_add_verification_data(keydir, keydest,
+				fit, noffset, comment, require_keys);
 		if (ret)
 			return ret;
 	}