futility: rwsig: Add support for images with FMAP

If an FMAP is detected in the rwsig image file, use it
to determine the location of:
 - RW region
 - RW signature
 - public key in RO region

futility show uses that information to verify the signature,
and futility sign uses it is correctly resign the image,
and replace the public key a well.

This also adds tests for this use case. hammer_dev.bin sample
image uses huge RO public key and RW signature regions to make
sure all keys up to RSA-8192 can be used.

BRANCH=none
BUG=chrome-os-partner:62321
TEST=make -j
TEST=./build/futility/futility --debug show \
                    --pubkey hammer.vbpubk2 hammer.bin
TEST=./build/futility/futility --debug show hammer.bin
TEST=cp hammer.bin hammer.bin.orig
     ./build/futility/futility --debug sign \
       --prikey hammer.vbprik2 hammer.bin
     diff hammer.bin hammer.bin.orig => identical
TEST=openssl genrsa -3 -out hammer2.pem 2048
     futility create --desc="Hammer 2nd key" hammer2.pem \
       hammer2
     ./build/futility/futility --debug sign \
       --version 2 --prikey hammer2.vbprik2 hammer.bin
     These 2 commands succeed, but show different keys:
     ./build/futility/futility --debug show hammer.bin
     ./build/futility/futility --debug show hammer.bin.orig
TEST=make runtests

Change-Id: I2cebc421eaf97d1b92c9a58afc238d41487d0f6d
Reviewed-on: https://chromium-review.googlesource.com/445536
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

5 files changed, 253 insertions, 56 deletions

diff --git a/futility/cmd_sign.c b/futility/cmd_sign.c
index d0c053b4..5b686342 100644
--- a/futility/cmd_sign.c
+++ b/futility/cmd_sign.c
@@ -479,30 +479,27 @@ static void print_help_rwsig(int argc, char *argv[])
 	       "\n"
 	       "This signs a %s.\n"
 	       "\n"
-	       "The INFILE is a binary blob of arbitrary size."
-	       " It is signed using the\n"
+	       "The INFILE is a binary blob of arbitrary size. It is signed using the\n"
 	       "private key and the vb21_signature blob emitted.\n"
 	       "\n"
-	       "If no OUTFILE is specified, the INFILE should contain"
-	       " an existing\n"
-	       "vb21_signature blob near its end. The data_size from that"
-	       " signature is\n"
-	       "used to re-sign a portion of the INFILE, and the old"
-	       " signature blob is\n"
+	       "If no OUTFILE is specified, the INFILE should contain an existing\n"
+	       "vb21_signature blob near its end. The data_size from that signature is\n"
+	       "used to re-sign a portion of the INFILE, and the old signature blob is\n"
 	       "replaced.\n"
+	       "Alternatively, if INFILE contains an FMAP, RW and signatures offsets\n"
+	       "are read from that table, and, if a public key is provided, the\n"
+	       "public key is replaced in the RO image.\n"
 	       "\n"
 	       "Options:\n"
 	       "\n"
-	       "  --prikey      FILE.vbprik2      "
-	       "Private key in vb2 format (required)\n"
-	       "  --sig_size    NUM               "
-	       "Offset from the end of INFILE where the\n"
-	       "                                    "
-	       "signature blob should be located\n"
-	       "                                    "
-	       "(default 1024 bytes)\n"
-	       "  --data_size   NUM               "
-	       "Number of bytes of INFILE to sign\n"
+	       "  --prikey      FILE.vbprik2      Private key in vb2 format (required)\n"
+	       "  --version     NUM               Public key version if we are replacing"
+	       "                                  the key in INFILE (default: 1)\n"
+	       "  --sig_size    NUM               Offset from the end of INFILE where the\n"
+	       "                                    signature blob should be located, if\n"
+	       "                                    the file does not contain an FMAP.\n"
+	       "                                    (default 1024 bytes)\n"
+	       "  --data_size   NUM               Number of bytes of INFILE to sign\n"
 	       "\n",
 	       argv[0],
 	       futil_file_type_name(FILE_TYPE_RWSIG),
diff --git a/futility/file_type_rwsig.c b/futility/file_type_rwsig.c
index 9561f6cf..1323da41 100644
--- a/futility/file_type_rwsig.c
+++ b/futility/file_type_rwsig.c
@@ -22,6 +22,7 @@
 #include "2rsa.h"
 #include "2sha.h"
 #include "file_type.h"
+#include "fmap.h"
 #include "futility.h"
 #include "futility_options.h"
 #include "vb21_common.h"
@@ -61,12 +62,16 @@ static void show_sig(const char *name, const struct vb21_signature *sig)
 int ft_show_rwsig(const char *name, uint8_t *buf, uint32_t len, void *nuthin)
 {
 	const struct vb21_signature *sig = 0;
+	const struct vb21_packed_key *pkey = show_option.pkey;
 	struct vb2_public_key key;
 	uint8_t workbuf[VB2_VERIFY_DATA_WORKBUF_BYTES]
 		 __attribute__ ((aligned (VB2_WORKBUF_ALIGN)));
 	struct vb2_workbuf wb;
 	uint32_t data_size, sig_size = SIGNATURE_RSVD_SIZE;
+	uint32_t total_data_size = 0;
 	uint8_t *data;
+	FmapHeader *fmap;
+	int i;
 
 	Debug("%s(): name %s\n", __func__, name);
 	Debug("%s(): len  0x%08x (%d)\n", __func__, len, len);
@@ -82,8 +87,55 @@ int ft_show_rwsig(const char *name, uint8_t *buf, uint32_t len, void *nuthin)
 		}
 		data = show_option.fv;
 		data_size = show_option.fv_size;
+		total_data_size = show_option.fv_size;
+	} else if ((fmap = fmap_find(buf, len))) {
+		/* This looks like a full image. */
+		FmapAreaHeader *fmaparea;
+
+		Debug("Found an FMAP!\n");
+
+		/* If no public key is provided, use the one packed in RO
+		 * image, and print that. */
+		if (!pkey) {
+			pkey = (const struct vb21_packed_key *)
+				fmap_find_by_name(buf, len, fmap, "KEY_RO", 0);
+
+			if (pkey)
+				ft_show_vb21_pubkey(name, (uint8_t *)pkey,
+						pkey->c.total_size, NULL);
+		}
+
+		sig = (const struct vb21_signature *)
+			fmap_find_by_name(buf, len, fmap, "SIG_RW", &fmaparea);
+		if (!sig) {
+			Debug("No SIG_RW in FMAP.\n");
+			return 1;
+		}
+
+		sig_size = fmaparea->area_size;
+
+		Debug("Looking for signature at 0x%x (0x%x)\n",
+			(uint8_t*)sig - buf, sig_size);
+
+		if (VB2_SUCCESS != vb21_verify_signature(sig, sig_size))
+			return 1;
+
+		show_sig(name, sig);
+		data = fmap_find_by_name(buf, len, fmap, "EC_RW", &fmaparea);
+		data_size = sig->data_size;
+		/*
+		 * TODO(crosbug.com/p/62231): EC_RW region should not include
+		 * the signature.
+		 */
+		total_data_size = fmaparea->area_size-sig_size;
+
+		if (!data) {
+			Debug("No EC_RW in FMAP.\n");
+			return 1;
+		}
 	} else {
-		/* Where would it be? */
+		/* Or maybe this is just the RW portion, that does not
+		 * contain a FMAP. */
 		if (show_option.sig_size)
 			sig_size = show_option.sig_size;
 
@@ -99,24 +151,30 @@ int ft_show_rwsig(const char *name, uint8_t *buf, uint32_t len, void *nuthin)
 			show_sig(name, sig);
 			data = buf;
 			data_size = sig->data_size;
+			total_data_size = len - sig_size;
 		} else {
 			return 1;
 		}
 	}
 
-	if (!show_option.pkey) {
+	if (!pkey) {
 		printf("No public key available to verify with\n");
 		return show_option.strict;
 	}
 
 	/* We already did this once, so it should work again */
 	if (vb21_unpack_key(&key,
-			    (const uint8_t *)show_option.pkey,
-			    show_option.pkey->c.total_size)) {
+			    (const uint8_t *)pkey,
+			    pkey->c.total_size)) {
 		Debug("Can't unpack pubkey\n");
 		return 1;
 	}
 
+	if (data_size > total_data_size) {
+		Debug("Invalid signature data_size: bigger than total area size.\n");
+		return 1;
+	}
+
 	/* The sig is destroyed by the verify operation, so make a copy */
 	{
 		uint8_t sigbuf[sig->c.total_size];
@@ -128,7 +186,15 @@ int ft_show_rwsig(const char *name, uint8_t *buf, uint32_t len, void *nuthin)
 				     (struct vb21_signature *)sigbuf,
 				     (const struct vb2_public_key *)&key,
 				     &wb)) {
-			printf("Signature verification failed\n");
+			fprintf(stderr, "Signature verification failed\n");
+			return 1;
+		}
+	}
+
+	/* Check that the rest of region is padded with 0xff. */
+	for (i = data_size; i < total_data_size; i++) {
+		if (data[i] != 0xff) {
+			fprintf(stderr, "Padding verification failed\n");
 			return 1;
 		}
 	}
@@ -137,11 +203,18 @@ int ft_show_rwsig(const char *name, uint8_t *buf, uint32_t len, void *nuthin)
 	return 0;
 }
 
-int ft_sign_rwsig(const char *name, uint8_t *buf, uint32_t len, void *data)
+int ft_sign_rwsig(const char *name, uint8_t *buf, uint32_t len, void *nuthin)
 {
-	struct vb21_signature *sig = 0;
+	struct vb21_signature *tmp_sig = 0;
+	struct vb2_public_key *pubkey = 0;
+	struct vb21_packed_key *packedkey = 0;
+	uint8_t *keyb_data = 0;
+	uint32_t keyb_size;
+	uint8_t* data = buf; /* data to be signed */
 	uint32_t r, data_size = len, sig_size = SIGNATURE_RSVD_SIZE;
 	int retval = 1;
+	FmapHeader *fmap = NULL;
+	FmapAreaHeader *fmaparea;
 
 	Debug("%s(): name %s\n", __func__, name);
 	Debug("%s(): len  0x%08x (%d)\n", __func__, len, len);
@@ -150,25 +223,56 @@ int ft_sign_rwsig(const char *name, uint8_t *buf, uint32_t len, void *data)
 	if (sign_option.inout_file_count < 2) {
 		const struct vb21_signature *old_sig;
 
-		/* Where would it be? */
-		if (sign_option.sig_size)
-			sig_size = sign_option.sig_size;
+		fmap = fmap_find(buf, len);
 
-		Debug("Looking for old signature at 0x%x\n", len - sig_size);
+		if (fmap) {
+			/* This looks like a full image. */
+			Debug("Found an FMAP!\n");
 
-		if (len < sig_size) {
-			fprintf(stderr, "File is too small\n");
-			return 1;
+			old_sig = (const struct vb21_signature *)
+				fmap_find_by_name(buf, len, fmap, "SIG_RW",
+						  &fmaparea);
+			if (!old_sig) {
+				Debug("No SIG_RW in FMAP.\n");
+				goto done;
+			}
+
+			sig_size = fmaparea->area_size;
+
+			Debug("Looking for signature at 0x%x (0x%x)\n",
+				(uint8_t*)old_sig - buf, sig_size);
+
+			data = fmap_find_by_name(buf, len, fmap, "EC_RW",
+						 &fmaparea);
+			if (!data) {
+				Debug("No EC_RW in FMAP.\n");
+				goto done;
+			}
+		} else {
+			/* Or maybe this is just the RW portion, that does not
+			 * contain a FMAP. */
+			if (sign_option.sig_size)
+				sig_size = sign_option.sig_size;
+
+			Debug("Looking for old signature at 0x%x\n",
+				len - sig_size);
+
+			if (len < sig_size) {
+				fprintf(stderr, "File is too small\n");
+				goto done;
+			}
+
+			/* Take a look */
+			old_sig = (const struct vb21_signature *)
+				(buf + len - sig_size);
 		}
 
-		/* Take a look */
-		old_sig = (const struct vb21_signature *)(buf + len - sig_size);
 		if (vb21_verify_signature(old_sig, sig_size)) {
 			fprintf(stderr, "Can't find a valid signature\n");
-			return 1;
+			goto done;
 		}
 
-		/* Use the same exent again */
+		/* Use the same extent again */
 		data_size = old_sig->data_size;
 
 		Debug("Found sig: data_size is 0x%x (%d)\n", data_size,
@@ -180,7 +284,7 @@ int ft_sign_rwsig(const char *name, uint8_t *buf, uint32_t len, void *data)
 		data_size = sign_option.data_size;
 
 	/* Sign the blob */
-	r = vb21_sign_data(&sig, buf, data_size, sign_option.prikey, 0);
+	r = vb21_sign_data(&tmp_sig, data, data_size, sign_option.prikey, 0);
 	if (r) {
 		fprintf(stderr,
 			"Unable to sign data (error 0x%08x, if that helps)\n",
@@ -190,16 +294,16 @@ int ft_sign_rwsig(const char *name, uint8_t *buf, uint32_t len, void *data)
 
 	if (sign_option.inout_file_count < 2) {
 		/* Overwrite the old signature */
-		if (sig->c.total_size > sig_size) {
+		if (tmp_sig->c.total_size > sig_size) {
 			fprintf(stderr, "New sig is too large (%d > %d)\n",
-				sig->c.total_size, sig_size);
+				tmp_sig->c.total_size, sig_size);
 			goto done;
 		}
 		memset(buf + len - sig_size, 0xff, sig_size);
-		memcpy(buf + len - sig_size, sig, sig->c.total_size);
+		memcpy(buf + len - sig_size, tmp_sig, tmp_sig->c.total_size);
 	} else {
 		/* Write the signature to a new file */
-		r = vb21_write_object(sign_option.outfile, sig);
+		r = vb21_write_object(sign_option.outfile, tmp_sig);
 		if (r) {
 			fprintf(stderr, "Unable to write sig"
 				" (error 0x%08x, if that helps)\n", r);
@@ -207,24 +311,112 @@ int ft_sign_rwsig(const char *name, uint8_t *buf, uint32_t len, void *data)
 		}
 	}
 
+	/* For full images, let's replace the public key in RO. */
+	if (fmap) {
+		uint8_t *new_pubkey;
+		uint8_t *pubkey_buf = 0;
+
+		/* Create the public key */
+		if (vb2_public_key_alloc(&pubkey,
+						sign_option.prikey->sig_alg)) {
+			fprintf(stderr, "Unable to allocate the public key\n");
+			goto done;
+		}
+
+		/* Extract the keyb blob */
+		if (vb_keyb_from_rsa(sign_option.prikey->rsa_private_key,
+					&keyb_data, &keyb_size)) {
+			fprintf(stderr, "Couldn't extract the public key\n");
+			goto done;
+		}
+
+		/*
+		 * Copy the keyb blob to the public key's buffer, because that's
+		 * where vb2_unpack_key_data() and vb2_public_key_pack() expect
+		 * to find it.
+		 */
+		pubkey_buf = vb2_public_key_packed_data(pubkey);
+		memcpy(pubkey_buf, keyb_data, keyb_size);
+
+		/* Fill in the internal struct pointers */
+		if (vb2_unpack_key_data(pubkey, pubkey_buf, keyb_size)) {
+			fprintf(stderr, "Unable to unpack the public key blob\n");
+			goto done;
+		}
+
+		pubkey->hash_alg = sign_option.prikey->hash_alg;
+		pubkey->version = sign_option.version_specified ?
+			sign_option.version : 1;
+		vb2_public_key_set_desc(pubkey, sign_option.prikey->desc);
+
+		memcpy((struct vb2_id *)pubkey->id, &sign_option.prikey->id,
+			sizeof(*(pubkey->id)));
+
+		if (vb21_public_key_pack(&packedkey, pubkey)) {
+			goto done;
+		}
+
+		new_pubkey = fmap_find_by_name(buf, len, fmap, "KEY_RO",
+					&fmaparea);
+		if (!new_pubkey) {
+			Debug("No KEY_RO in FMAP.\n");
+			goto done;
+		}
+		/* Overwrite the old signature */
+		if (packedkey->c.total_size > fmaparea->area_size) {
+			fprintf(stderr, "New sig is too large (%d > %d)\n",
+			        packedkey->c.total_size, sig_size);
+			goto done;
+		}
+
+		memset(new_pubkey, 0xff, fmaparea->area_size);
+		memcpy(new_pubkey, packedkey, packedkey->c.total_size);
+	}
+
 	/* Finally */
 	retval = 0;
 done:
-	if (sig)
-		free(sig);
+	if (tmp_sig)
+		free(tmp_sig);
+	if (pubkey)
+		vb2_public_key_free(pubkey);
+	if (packedkey)
+		free(packedkey);
+	if (keyb_data)
+		free(keyb_data);
 
 	return retval;
 }
 
 enum futil_file_type ft_recognize_rwsig(uint8_t *buf, uint32_t len)
 {
+	FmapHeader *fmap;
+	const struct vb21_signature *sig = NULL;
+	uint32_t sig_size;
+
 	if (!vb21_verify_signature((const struct vb21_signature *)buf, len))
 		return FILE_TYPE_RWSIG;
 
-	if (len >= SIGNATURE_RSVD_SIZE &&
-	    !vb21_verify_signature((const struct vb21_signature *)
-				  (buf + len - SIGNATURE_RSVD_SIZE),
-				  SIGNATURE_RSVD_SIZE))
+	fmap = fmap_find(buf, len);
+	if (fmap) {
+		/* This looks like a full image. */
+		FmapAreaHeader *fmaparea;
+
+		sig = (const struct vb21_signature *)
+			fmap_find_by_name(buf, len, fmap, "SIG_RW", &fmaparea);
+
+		if (!sig)
+			return FILE_TYPE_UNKNOWN;
+
+		sig_size = fmaparea->area_size;
+	} else {
+		/* RW-only image */
+		sig = (const struct vb21_signature *)
+			(buf + len - SIGNATURE_RSVD_SIZE);
+		sig_size = SIGNATURE_RSVD_SIZE;
+	}
+
+	if (len >= sig_size && !vb21_verify_signature(sig, sig_size))
 		return FILE_TYPE_RWSIG;
 
 	return FILE_TYPE_UNKNOWN;
diff --git a/tests/futility/data/hammer_dev.bin b/tests/futility/data/hammer_dev.bin
new file mode 100755
index 00000000..d124fb6b
--- /dev/null
+++ b/tests/futility/data/hammer_dev.bin
diff --git a/tests/futility/run_test_scripts.sh b/tests/futility/run_test_scripts.sh
index b817c430..15a2580c 100755
--- a/tests/futility/run_test_scripts.sh
+++ b/tests/futility/run_test_scripts.sh
@@ -46,9 +46,9 @@ ${SCRIPTDIR}/test_dump_fmap.sh
 ${SCRIPTDIR}/test_gbb_utility.sh
 ${SCRIPTDIR}/test_load_fmap.sh
 ${SCRIPTDIR}/test_main.sh
+${SCRIPTDIR}/test_rwsig.sh
 ${SCRIPTDIR}/test_show_contents.sh
 ${SCRIPTDIR}/test_show_kernel.sh
-${SCRIPTDIR}/test_show_rwsig.sh
 ${SCRIPTDIR}/test_show_vs_verify.sh
 ${SCRIPTDIR}/test_show_usbpd1.sh
 ${SCRIPTDIR}/test_sign_firmware.sh
diff --git a/tests/futility/test_show_rwsig.sh b/tests/futility/test_rwsig.sh
index 915842d6..efdb6dbb 100755
--- a/tests/futility/test_show_rwsig.sh
+++ b/tests/futility/test_rwsig.sh
@@ -12,8 +12,7 @@ cd "$OUTDIR"
 DATADIR="${SCRIPTDIR}/data"
 TESTKEYS=${SRCDIR}/tests/testkeys
 
-# Do not test 8192 as the signature length is > 1024 bytes
-SIGS="1024 2048 4096 2048_exp3"
+SIGS="1024 2048 2048_exp3 4096 8192"
 HASHES="SHA1 SHA256 SHA512"
 
 set -o pipefail
@@ -24,20 +23,29 @@ for s in $SIGS; do
     for h in $HASHES; do
         pemfile=${TESTKEYS}/key_rsa${s}.pem
         outfile=${TMP}.${s}_${h}.new
-        infile=${DATADIR}/random_noise.bin
+        infile=${DATADIR}/hammer_dev.bin
         outkeys=${TMP}.${s}_${h}
-        outsig=${TMP}.${s}_${h}.signature
+        outfile=${TMP}.${s}_${h}.bin
 
         ${FUTILITY} create --desc "Test key" --hash_alg ${h} \
                     ${pemfile} ${outkeys}
 
+        # The input file should be correctly signed to start with
+        ${FUTILITY} show --type rwsig ${infile}
+
+        # Using the wrong key to verify it should fail
+        if ${FUTILITY} show --type rwsig --pubkey ${outkeys}.vbpubk2 \
+                       ${infile}; then
+            exit 1
+        fi
+
+        cp ${infile} ${outfile}
+
         ${FUTILITY} sign --type rwsig --prikey ${outkeys}.vbprik2 \
-                ${infile} ${outsig}
-        dd if=/dev/zero bs=$((4096 + 1024)) count=1 of=${outfile}
-        dd if=${infile} of=${outfile} conv=notrunc
-        dd if=${outsig} of=${outfile} bs=4096 seek=1 conv=notrunc
+                --version 2 ${outfile}
 
         ${FUTILITY} show --type rwsig --pubkey ${outkeys}.vbpubk2 ${outfile}
+        ${FUTILITY} show --type rwsig ${outfile}
     done
 done