[PATCH] mkimage: fit: Support signed configurations in 'auto' FITs

[Pegorer Massimo <Massimo.Pegorer@vimar.com>]

Hi,

The patch follows, as per discussion in email thread "Patch proposal
 - mkimage: fit: Support signed conf 'auto' FITs". Let me know if you
prefer something to be changed, or patch to be split in several
commits.

I have updated the man page with description of the new feature and
examples. Also fixed some wrong or misleading information.

===

mkimage: fit: Support signed configurations in 'auto' FITs

Extend support for signing in auto-generated (-f auto) FIT. Previously,
it was possible to get signed 'images' subnodes in the FIT using
options -g and -o together with -f auto. This patch allows signing
'configurations' subnodes instead of 'images' ones (which are hashed),
using option -f auto-conf instead of -f auto. Adding also -K <dtb> and
-r options, will add public key to <dtb> file with required = "conf"
property.

Summary:
    -f auto => FIT with crc32 images
    -f auto -g ... -o ... => FIT with signed images
    -f auto-conf -g ... -o ... => FIT with sha1 images and signed confs

Example: FIT with kernel, two device tree files, and signed
configurations; public key (needed to verify signatures) is
added to u-boot.dtb with required = "conf" property.

mkimage -f auto-conf -A arm -O linux -T kernel -C none -a 43e00000 \
        -e 0 -d vmlinuz -b /path/to/first.dtb -b /path/to/second.dtb \
        -k /folder/with/key-files -g keyname -o sha256,rsa4096 \
        -K u-boot.dtb -r kernel.itb

Example: Add public key with required = "conf" property to u-boot.dtb
without needing to sign anything. This will also create a useless FIT
named unused.itb.

mkimage -f auto-conf -d /dev/null -k /folder/with/key-files \
        -g keyname -o sha256,rsa4096 -K u-boot.dtb -r unused.itb

Signed-off-by: Massimo Pegorer <massimo.pegorer@vimar.com>
---
 doc/mkimage.1     | 119 ++++++++++++++++++++++++++++++++--------------
 tools/fit_image.c |  75 +++++++++++++++++++----------
 tools/imagetool.h |  10 +++-
 tools/mkimage.c   |  23 +++++++--
 4 files changed, 160 insertions(+), 67 deletions(-)

diff --git a/doc/mkimage.1 b/doc/mkimage.1
index 353ea8b2f7..d8727ec73c 100644
--- a/doc/mkimage.1
+++ b/doc/mkimage.1
@@ -22,7 +22,8 @@ mkimage \- generate images for U-Boot
 .SY mkimage
 .RI [ option\~ .\|.\|.\&]
 .BI \-f\~ image-tree-source-file\c
-.RB | auto
+.RB | auto\c
+.RB | auto-conf
 .I image-file-name
 .YS
 .
@@ -296,9 +297,9 @@ FIT. See
 for details on using external data.
 .
 .TP
-\fB\-f \fIimage-tree-source-file\fR | \fBauto
+\fB\-f \fIimage-tree-source-file\fR | \fBauto\fR | \fBauto-conf
 .TQ
-\fB\-\-fit \fIimage-tree-source-file\fR | \fBauto
+\fB\-\-fit \fIimage-tree-source-file\fR | \fBauto\fR | \fBauto-conf
 Image tree source file that describes the structure and contents of the
 FIT image.
 .IP
@@ -317,7 +318,25 @@ and
 options may be used to specify the image to include in the FIT and its
 attributes. No
 .I image-tree-source-file
-is required.
+is required. The
+.BR \-g ,
+.BR \-o ,
+and
+.B \-k
+or
+.B \-G
+options may be used to get \(oqimages\(cq signed subnodes in the generated
+auto FIT. Instead, to get \(oqconfigurations\(cq signed subnodes and
+\(oqimages\(cq hashed subnodes, pass
+.BR "\-f auto-conf".
+In this case
+.BR \-g ,
+.BR \-o ,
+and
+.B \-k
+or
+.B \-G
+are mandatory options.
 .
 .TP
 .B \-F
@@ -348,16 +367,16 @@ for use with signing, and a certificate
 necessary when embedding it into another device tree using
 .BR \-K .
 .I name
-defaults to the value of the signature node's \(oqkey-name-hint\(cq property,
-but may be overridden using
-.BR \-g .
+is the value of the signature node's \(oqkey-name-hint\(cq property.
 .
 .TP
 .BI \-G " key-file"
 .TQ
 .BI \-\-key\-file " key-file"
 Specifies the private key file to use when signing. This option may be used
-instead of \-k.
+instead of \-k. Useful when the private key file basename does not match
+\(oqkey-name-hint\(cq value. But note that it may lead to unexpected results
+when used together with -K and/or -k options.
 .
 .TP
 .BI \-K " key-destination"
@@ -373,49 +392,50 @@ CONFIG_OF_CONTROL in U-Boot.
 .BI \-g " key-name-hint"
 .TQ
 .BI \-\-key\-name\-hint " key-name-hint"
-Overrides the signature node's \(oqkey-name-hint\(cq property. This is
-especially useful when signing an image with
-.BR "\-f auto" .
-This is the
-.I name
-part of the key. The directory part is set by
-.BR \-k .
-This option also indicates that the images included in the FIT should be signed.
-If this option is specified, then
+Specifies the value of signature node \(oqkey-name-hint\(cq property for
+an automatically generated FIT image. It makes sense only when used with
+.B "\-f auto"
+or
+.BR "\-f auto-conf".
+This option also indicates that the images or configurations included in
+the FIT should be signed. If this option is specified, then
 .B \-o
 must be specified as well.
 .
 .TP
-.BI \-o " crypto" , checksum
+.BI \-o " checksum" , crypto
 .TQ
-.BI \-\-algo " crypto" , checksum
-Specifies the algorithm to be used for signing a FIT image. The default is
-taken from the signature node's \(oqalgo\(cq property.
+.BI \-\-algo " checksum" , crypto
+Specifies the algorithm to be used for signing a FIT image, overriding value
+taken from the signature node \(oqalgo\(cq property in the
+.IR image-tree-source-file .
+It is mandatory for automatically generated FIT.
+.IP
 The valid values for
-.I crypto
+.I checksum
 are:
 .RS
 .IP
 .TS
 lb.
-rsa2048
-rsa3072
-rsa4096
-ecdsa256
+sha1
+sha256
+sha384
+sha512
 .TE
 .RE
 .IP
 The valid values for
-.I checksum
-are
+.I crypto
+are:
 .RS
 .IP
 .TS
 lb.
-sha1
-sha256
-sha384
-sha512
+rsa2048
+rsa3072
+rsa4096
+ecdsa256
 .TE
 .RE
 .
@@ -423,9 +443,13 @@ sha512
 .B \-r
 .TQ
 .B \-\-key\-required
-Specifies that keys used to sign the FIT are required. This means that they
-must be verified for the image to boot. Without this option, the verification
-will be optional (useful for testing but not for release).
+Specifies that keys used to sign the FIT are required. This means that images
+or configurations signatures must be verified before using them (i.e. to
+boot). Without this option, the verification will be optional (useful for
+testing but not for release). It makes sense only when used with
+.BR \-K.
+When both, images and configurations, are signed, \(oqrequired\(cq property
+value will be "conf".
 .
 .TP
 .BI \-N " engine"
@@ -716,7 +740,7 @@ skipping those for which keys cannot be found. Also add a comment.
 .EE
 .RE
 .P
-Add public keys to u\-boot.dtb without needing a FIT to sign. This will also
+Add public key to u\-boot.dtb without needing a FIT to sign. This will also
 create a FIT containing an images node with no data named unused.itb.
 .RS
 .P
@@ -726,6 +750,16 @@ create a FIT containing an images node with no data named unused.itb.
 .EE
 .RE
 .P
+Add public key with required = "conf" property to u\-boot.dtb without needing
+a FIT to sign. This will also create a useless FIT named unused.itb.
+.RS
+.P
+.EX
+\fBmkimage \-f auto-conf \-d /dev/null \-k /public/signing\-keys \-g dev \\
+	\-o sha256,rsa2048 \-K u\-boot.dtb -r unused.itb
+.EE
+.RE
+.P
 Update an existing FIT image, signing it with additional keys.
 Add corresponding public keys into u\-boot.dtb. This will resign all images
 with keys that are available in the new directory. Images that request signing
@@ -768,6 +802,19 @@ file is required.
 	\-d vmlinuz \-k /secret/signing\-keys \-g dev \-o sha256,rsa2048 kernel.itb
 .EE
 .RE
+.P
+Create a FIT image containing a kernel and some device tree files, signing
+each configuration, using automatic mode. Moreover, the public key needed to
+verify signatures is added to u\-boot.dtb with required = "conf" property.
+.RS
+.P
+.EX
+\fBmkimage \-f auto-conf \-A arm \-O linux \-T kernel \-C none \-a 43e00000 \\
+	\-e 0 \-d vmlinuz \-b /path/to/file\-1.dtb \-b /path/to/file\-2.dtb \\
+	\-k /folder/with/signing\-keys \-g dev \-o sha256,rsa2048 \\
+	\-K u\-boot.dtb -r kernel.itb
+.EE
+.RE
 .
 .SH SEE ALSO
 .BR dtc (1),
diff --git a/tools/fit_image.c b/tools/fit_image.c
index 923a9755b7..d15a377779 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -199,36 +199,59 @@ static void get_basename(char *str, int size, const char *fname)
 }
 
 /**
- * add_hash_node() - Add a hash or signature node
+ * fit_add_hash_or_sign() - Add a hash or signature node
  *
  * @params: Image parameters
  * @fdt: Device tree to add to (in sequential-write mode)
+ * @is_images_subnode: true to add hash even if key name hint is provided
  *
- * If there is a key name hint, try to sign the images. Otherwise, just add a
- * CRC.
- *
- * Return: 0 on success, or -1 on failure
+ * If do_add_hash is false (default) and there is a key name hint, try to add
+ * a sign node to parent. Otherwise, just add a CRC. Rationale: if conf have
+ * to be signed, image/dt have to be hashed even if there is a key name hint.
  */
-static int add_hash_node(struct image_tool_params *params, void *fdt)
+static void fit_add_hash_or_sign(struct image_tool_params *params, void *fdt,
+				 bool is_images_subnode)
 {
-	if (params->keyname) {
-		if (!params->algo_name) {
-			fprintf(stderr,
-				"%s: Algorithm name must be specified\n",
-				params->cmdname);
-			return -1;
+	const char *hash_algo = "crc32";
+	bool do_hash = false;
+	bool do_sign = false;
+
+	switch (params->auto_fit) {
+	case AF_OFF:
+		break;
+	case AF_HASHED_IMG:
+		do_hash = is_images_subnode;
+		break;
+	case AF_SIGNED_IMG:
+		do_sign = is_images_subnode;
+		break;
+	case AF_SIGNED_CONF:
+		if (is_images_subnode) {
+			do_hash = true;
+			hash_algo = "sha1";
+		} else {
+			do_sign = true;
 		}
+		break;
+	default:
+		fprintf(stderr,
+			"%s: Unsupported auto FIT mode %u\n",
+			params->cmdname, params->auto_fit);
+		break;
+	}
+
+	if (do_hash) {
+		fdt_begin_node(fdt, FIT_HASH_NODENAME);
+		fdt_property_string(fdt, FIT_ALGO_PROP, hash_algo);
+		fdt_end_node(fdt);
+	}
 
-		fdt_begin_node(fdt, "signature-1");
+	if (do_sign) {
+		fdt_begin_node(fdt, FIT_SIG_NODENAME);
 		fdt_property_string(fdt, FIT_ALGO_PROP, params->algo_name);
 		fdt_property_string(fdt, FIT_KEY_HINT, params->keyname);
-	} else {
-		fdt_begin_node(fdt, "hash-1");
-		fdt_property_string(fdt, FIT_ALGO_PROP, "crc32");
+		fdt_end_node(fdt);
 	}
-
-	fdt_end_node(fdt);
-	return 0;
 }
 
 /**
@@ -269,9 +292,7 @@ static int fit_write_images(struct image_tool_params *params, char *fdt)
 	ret = fdt_property_file(params, fdt, FIT_DATA_PROP, params->datafile);
 	if (ret)
 		return ret;
-	ret = add_hash_node(params, fdt);
-	if (ret)
-		return ret;
+	fit_add_hash_or_sign(params, fdt, true);
 	fdt_end_node(fdt);
 
 	/* Now the device tree files if available */
@@ -294,7 +315,7 @@ static int fit_write_images(struct image_tool_params *params, char *fdt)
 				    genimg_get_arch_short_name(params->arch));
 		fdt_property_string(fdt, FIT_COMP_PROP,
 				    genimg_get_comp_short_name(IH_COMP_NONE));
-		ret = add_hash_node(params, fdt);
+		fit_add_hash_or_sign(params, fdt, true);
 		if (ret)
 			return ret;
 		fdt_end_node(fdt);
@@ -314,7 +335,7 @@ static int fit_write_images(struct image_tool_params *params, char *fdt)
 					params->fit_ramdisk);
 		if (ret)
 			return ret;
-		ret = add_hash_node(params, fdt);
+		fit_add_hash_or_sign(params, fdt, true);
 		if (ret)
 			return ret;
 		fdt_end_node(fdt);
@@ -366,6 +387,7 @@ static void fit_write_configs(struct image_tool_params *params, char *fdt)
 
 		snprintf(str, sizeof(str), FIT_FDT_PROP "-%d", upto);
 		fdt_property_string(fdt, FIT_FDT_PROP, str);
+		fit_add_hash_or_sign(params, fdt, false);
 		fdt_end_node(fdt);
 	}
 
@@ -378,6 +400,7 @@ static void fit_write_configs(struct image_tool_params *params, char *fdt)
 		if (params->fit_ramdisk)
 			fdt_property_string(fdt, FIT_RAMDISK_PROP,
 					    FIT_RAMDISK_PROP "-1");
+		fit_add_hash_or_sign(params, fdt, false);
 
 		fdt_end_node(fdt);
 	}
@@ -721,7 +744,7 @@ static int fit_handle_file(struct image_tool_params *params)
 	sprintf (tmpfile, "%s%s", params->imagefile, MKIMAGE_TMPFILE_SUFFIX);
 
 	/* We either compile the source file, or use the existing FIT image */
-	if (params->auto_its) {
+	if (params->auto_fit) {
 		if (fit_build(params, tmpfile)) {
 			fprintf(stderr, "%s: failed to build FIT\n",
 				params->cmdname);
@@ -905,7 +928,7 @@ static int fit_extract_contents(void *ptr, struct image_tool_params *params)
 
 static int fit_check_params(struct image_tool_params *params)
 {
-	if (params->auto_its)
+	if (params->auto_fit)
 		return 0;
 	return	((params->dflag && params->fflag) ||
 		 (params->fflag && params->lflag) ||
diff --git a/tools/imagetool.h b/tools/imagetool.h
index ca7c2e48ba..fdceea46c0 100644
--- a/tools/imagetool.h
+++ b/tools/imagetool.h
@@ -39,6 +39,14 @@ struct content_info {
 	const char *fname;
 };
 
+/* FIT auto generation modes */
+enum af_mode {
+	AF_OFF = 0,	/* Needs .its or existing FIT to be provided */
+	AF_HASHED_IMG,	/* Auto FIT with crc32 hashed images subnodes */
+	AF_SIGNED_IMG,	/* Auto FIT with signed images subnodes */
+	AF_SIGNED_CONF,	/* Auto FIT with sha1 images and signed configs */
+};
+
 /*
  * This structure defines all such variables those are initialized by
  * mkimage and dumpimage main core and need to be referred by image
@@ -79,7 +87,7 @@ struct image_tool_params {
 	int require_keys;	/* 1 to mark signing keys as 'required' */
 	int file_size;		/* Total size of output file */
 	int orig_file_size;	/* Original size for file before padding */
-	bool auto_its;		/* Automatically create the .its file */
+	enum af_mode auto_fit;	/* Automatically create the FIT */
 	int fit_image_type;	/* Image type to put into the FIT */
 	char *fit_ramdisk;	/* Ramdisk file to include */
 	struct content_info *content_head;	/* List of files to include */
diff --git a/tools/mkimage.c b/tools/mkimage.c
index 30c6df7708..75b72420b9 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -104,7 +104,7 @@ static void usage(const char *msg)
 		"          -v ==> verbose\n",
 		params.cmdname);
 	fprintf(stderr,
-		"       %s [-D dtc_options] [-f fit-image.its|-f auto|-F] [-b <dtb> [-b <dtb>]] [-E] [-B size] [-i <ramdisk.cpio.gz>] fit-image\n"
+		"       %s [-D dtc_options] [-f fit-image.its|-f auto|-f auto-conf|-F] [-b <dtb> [-b <dtb>]] [-E] [-B size] [-i <ramdisk.cpio.gz>] fit-image\n"
 		"           <dtb> file is used with -f auto, it may occur multiple times.\n",
 		params.cmdname);
 	fprintf(stderr,
@@ -271,7 +271,10 @@ static void process_args(int argc, char **argv)
 			break;
 		case 'f':
 			datafile = optarg;
-			params.auto_its = !strcmp(datafile, "auto");
+			if (!strcmp(datafile, "auto"))
+				params.auto_fit = AF_HASHED_IMG;
+			else if (!strcmp(datafile, "auto-conf"))
+				params.auto_fit = AF_SIGNED_CONF;
 			/* fallthrough */
 		case 'F':
 			/*
@@ -283,6 +286,7 @@ static void process_args(int argc, char **argv)
 			break;
 		case 'g':
 			params.keyname = optarg;
+			break;
 		case 'G':
 			params.keyfile = optarg;
 			break;
@@ -370,6 +374,17 @@ static void process_args(int argc, char **argv)
 	if (optind < argc)
 		params.imagefile = argv[optind];
 
+	if (params.auto_fit == AF_SIGNED_CONF) {
+		if (!params.keyname || !params.algo_name)
+			usage("Auto FIT with signed configs requires -f auto-conf "
+				"-g <key name hint> -o <algorithm>");
+	} else if (params.auto_fit == AF_HASHED_IMG && params.keyname) {
+		params.auto_fit = AF_SIGNED_IMG;
+		if (!params.algo_name)
+			usage("Auto FIT with signed images requires -f auto "
+				"-g <key name hint> -o <algorithm>");
+	}
+
 	/*
 	 * For auto-generated FIT images we need to know the image type to put
 	 * in the FIT, which is separate from the file's image type (which
@@ -377,8 +392,8 @@ static void process_args(int argc, char **argv)
 	 */
 	if (params.type == IH_TYPE_FLATDT) {
 		params.fit_image_type = type ? type : IH_TYPE_KERNEL;
-		/* For auto_its, datafile is always 'auto' */
-		if (!params.auto_its)
+		/* For auto-FIT, datafile has to be provided with -d */
+		if (!params.auto_fit)
 			params.datafile = datafile;
 		else if (!params.datafile)
 			usage("Missing data file for auto-FIT (use -d)");
-- 
2.34.1