[PATCH v2 1/9] tools: mkeficapsule: add firmwware image signing

Heinrich Schuchardt xypron.glpk at gmx.de
Mon Aug 2 08:18:37 CEST 2021



On 8/2/21 5:30 AM, AKASHI Takahiro wrote:
> Heinrich,
>
> On Sun, Aug 01, 2021 at 11:21:55AM +0200, Heinrich Schuchardt wrote:
>> On 7/27/21 11:10 AM, AKASHI Takahiro wrote:
>>> With this enhancement, mkeficapsule will be able to sign a capsule
>>> file when it is created. A signature added will be used later
>>> in the verification at FMP's SetImage() call.
>>>
>>> To do that, We need specify additional command parameters:
>>>     -monotonic-cout <count> : monotonic count
>>>     -private-key <private key file> : private key file
>>>     -certificate <certificate file> : certificate file
>>> Only when all of those parameters are given, a signature will be added
>>> to a capsule file.
>>>
>>> Users are expected to maintain and increment the monotonic count at
>>> every time of the update for each firmware image.
>>>
>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
>>> ---
>>>    tools/Kconfig        |   7 +
>>>    tools/Makefile       |   8 +-
>>>    tools/mkeficapsule.c | 332 +++++++++++++++++++++++++++++++++++++++----
>>>    3 files changed, 316 insertions(+), 31 deletions(-)
>>>
>>> diff --git a/tools/Kconfig b/tools/Kconfig
>>> index d6f82cd949b5..9a37ed035311 100644
>>> --- a/tools/Kconfig
>>> +++ b/tools/Kconfig
>>> @@ -20,4 +20,11 @@ config TOOLS_LIBCRYPTO
>>>    	  This selection does not affect target features, such as runtime FIT
>>>    	  signature verification.
>>>
>>> +config TOOLS_MKEFICAPSULE
>>> +	bool "Build efimkcapsule command"
>>> +	default y if EFI_CAPSULE_ON_DISK
>>> +	help
>>> +	  This command allows users to create a UEFI capsule file and,
>>> +	  optionally sign that file. If you want to enable UEFI capsule
>>> +	  update feature on your target, you certainly need this.
>>>    endmenu
>>> diff --git a/tools/Makefile b/tools/Makefile
>>> index bae3f95c4995..af8536489652 100644
>>> --- a/tools/Makefile
>>> +++ b/tools/Makefile
>>> @@ -245,8 +245,12 @@ hostprogs-$(CONFIG_MIPS) += mips-relocs
>>>    hostprogs-$(CONFIG_ASN1_COMPILER)	+= asn1_compiler
>>>    HOSTCFLAGS_asn1_compiler.o = -idirafter $(srctree)/include
>>>
>>> -mkeficapsule-objs	:= mkeficapsule.o $(LIBFDT_OBJS)
>>> -hostprogs-$(CONFIG_EFI_HAVE_CAPSULE_SUPPORT) += mkeficapsule
>>> +HOSTLDLIBS_mkeficapsule += -luuid
>>> +ifeq ($(CONFIG_TOOLS_LIBCRYPTO),y)
>>> +HOSTLDLIBS_mkeficapsule += \
>>> +	$(shell pkg-config --libs libssl libcrypto 2> /dev/null || echo "-lssl -lcrypto")
>>
>> Please, add package pkg-config to the build dependencies enumerated in
>> doc/build/gcc.rst.
>
> Already there: libssl-dev

It is *pkg-config* that is missing.

>
>>> +endif
>>> +hostprogs-$(CONFIG_TOOLS_MKEFICAPSULE) += mkeficapsule
>>>
>>>    # We build some files with extra pedantic flags to try to minimize things
>>>    # that won't build on some weird host compiler -- though there are lots of
>>> diff --git a/tools/mkeficapsule.c b/tools/mkeficapsule.c
>>> index 4995ba4e0c2a..798706c7b5f7 100644
>>> --- a/tools/mkeficapsule.c
>>> +++ b/tools/mkeficapsule.c
>>> @@ -15,6 +15,16 @@
>>>    #include <sys/stat.h>
>>>    #include <sys/types.h>
>>>
>>> +#include <linux/kconfig.h>
>>> +#ifdef CONFIG_TOOLS_LIBCRYPTO
>>> +#include <openssl/asn1.h>
>>> +#include <openssl/bio.h>
>>> +#include <openssl/evp.h>
>>> +#include <openssl/err.h>
>>> +#include <openssl/pem.h>
>>> +#include <openssl/pkcs7.h>
>>> +#endif
>>> +
>>>    typedef __u8 u8;
>>>    typedef __u16 u16;
>>>    typedef __u32 u32;
>>> @@ -38,12 +48,25 @@ efi_guid_t efi_guid_image_type_uboot_fit =
>>>    		EFI_FIRMWARE_IMAGE_TYPE_UBOOT_FIT_GUID;
>>>    efi_guid_t efi_guid_image_type_uboot_raw =
>>>    		EFI_FIRMWARE_IMAGE_TYPE_UBOOT_RAW_GUID;
>>> +efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
>>> +
>>> +#ifdef CONFIG_TOOLS_LIBCRYPTO
>>> +static const char *opts_short = "f:r:i:I:v:p:c:m:dh";
>>> +#else
>>> +static const char *opts_short = "f:r:i:I:v:h";
>>> +#endif
>>>
>>>    static struct option options[] = {
>>>    	{"fit", required_argument, NULL, 'f'},
>>>    	{"raw", required_argument, NULL, 'r'},
>>>    	{"index", required_argument, NULL, 'i'},
>>>    	{"instance", required_argument, NULL, 'I'},
>>> +#ifdef CONFIG_TOOLS_LIBCRYPTO
>>> +	{"private-key", required_argument, NULL, 'p'},
>>> +	{"certificate", required_argument, NULL, 'c'},
>>> +	{"monotonic-count", required_argument, NULL, 'm'},
>>> +	{"dump-sig", no_argument, NULL, 'd'},
>>> +#endif
>>>    	{"help", no_argument, NULL, 'h'},
>>>    	{NULL, 0, NULL, 0},
>>>    };
>>> @@ -57,16 +80,195 @@ static void print_usage(void)
>>>    	       "\t-r, --raw <raw image>       new raw image file\n"
>>>    	       "\t-i, --index <index>         update image index\n"
>>>    	       "\t-I, --instance <instance>   update hardware instance\n"
>>> +#ifdef CONFIG_TOOLS_LIBCRYPTO
>>> +	       "\t-p, --private-key <privkey file>  private key file\n"
>>> +	       "\t-c, --certificate <cert file>     signer's certificate file\n"
>>> +	       "\t-m, --monotonic-count <count>     monotonic count\n"
>>> +	       "\t-d, --dump_sig              dump signature (*.p7)\n"
>>> +#endif
>>>    	       "\t-h, --help                  print a help message\n",
>>>    	       tool_name);
>>>    }
>>>
>>
>> Please, add Sphinx documentation.
>
> I added the man page. Why need another different format of doc?
> I think that doc/develop/uefi/uefi.rst gives you an enough
> introduction to the command.
> (Although the doc will have to been updated due to the latest change
> of mkeficapsule syntax that I'm also proposing.)
>
> Actually, there is no sphinx doc for any host tools.
>
>>> +struct auth_context {
>>> +	char *key_file;
>>> +	char *cert_file;
>>> +	u8 *image_data;
>>> +	size_t image_size;
>>> +	struct efi_firmware_image_authentication auth;
>>> +	u8 *sig_data;
>>> +	size_t sig_size;
>>> +};
>>> +
>>> +static int dump_sig;
>>> +
>>> +#ifdef CONFIG_TOOLS_LIBCRYPTO
>>> +static EVP_PKEY *fileio_read_pkey(const char *filename)
>>> +{
>>> +	EVP_PKEY *key = NULL;
>>> +	BIO *bio;
>>> +
>>> +	bio = BIO_new_file(filename, "r");
>>> +	if (!bio)
>>> +		goto out;
>>> +
>>> +	key = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
>>> +
>>> +out:
>>> +	BIO_free_all(bio);
>>> +	if (!key) {
>>> +		printf("Can't load key from file '%s'\n", filename);
>>> +		ERR_print_errors_fp(stderr);
>>> +	}
>>> +
>>> +	return key;
>>> +}
>>> +
>>
>> Please, add Sphinx documentation for all functions.
>
> Yeah, but "all" is a too forcible requirement.
> There is no source code of host tools to meet the requirement.
> Actually, most don't have even one description of a function.
>
> I think that, if it is a really required element in the source,
> it should be explicitly described somewhere under "doc".
>
>>> +static X509 *fileio_read_cert(const char *filename)
>>> +{
>>> +	X509 *cert = NULL;
>>> +	BIO *bio;
>>> +
>>> +	bio = BIO_new_file(filename, "r");
>>> +	if (!bio)
>>> +		goto out;
>>> +
>>> +	cert = PEM_read_bio_X509(bio, NULL, NULL, NULL);
>>> +
>>> +out:
>>> +	BIO_free_all(bio);
>>> +	if (!cert) {
>>> +		printf("Can't load certificate from file '%s'\n", filename);
>>> +		ERR_print_errors_fp(stderr);
>>> +	}
>>> +
>>> +	return cert;
>>> +}
>>> +
>>> +static int create_auth_data(struct auth_context *ctx)
>>> +{
>>> +	EVP_PKEY *key = NULL;
>>> +	X509 *cert = NULL;
>>> +	BIO *data_bio = NULL;
>>> +	const EVP_MD *md;
>>> +	PKCS7 *p7;
>>> +	int flags, ret = -1;
>>> +
>>> +	OpenSSL_add_all_digests();
>>> +	OpenSSL_add_all_ciphers();
>>> +	ERR_load_crypto_strings();
>>> +
>>> +	key = fileio_read_pkey(ctx->key_file);
>>> +	if (!key)
>>> +		goto err;
>>> +	cert = fileio_read_cert(ctx->cert_file);
>>> +	if (!cert)
>>> +		goto err;
>>> +
>>> +	/*
>>> +	 * create a BIO, containing:
>>> +	 *  * firmware image
>>> +	 *  * monotonic count
>>> +	 * in this order!
>>> +	 * See EDK2's FmpAuthenticatedHandlerRsa2048Sha256()
>>> +	 */
>>> +	data_bio = BIO_new(BIO_s_mem());
>>> +	BIO_write(data_bio, ctx->image_data, ctx->image_size);
>>> +	BIO_write(data_bio, &ctx->auth.monotonic_count,
>>> +		  sizeof(ctx->auth.monotonic_count));
>>> +
>>> +	md = EVP_get_digestbyname("SHA256");
>>> +	if (!md)
>>> +		goto err;
>>> +
>>> +	/* create signature */
>>> +	/* TODO: maybe add PKCS7_NOATTR and PKCS7_NOSMIMECAP */
>>> +	flags = PKCS7_BINARY | PKCS7_DETACHED;
>>> +	p7 = PKCS7_sign(NULL, NULL, NULL, data_bio, flags | PKCS7_PARTIAL);
>>> +	if (!p7)
>>> +		goto err;
>>> +	if (!PKCS7_sign_add_signer(p7, cert, key, md, flags))
>>> +		goto err;
>>> +	if (!PKCS7_final(p7, data_bio, flags))
>>> +		goto err;
>>> +
>>> +	/* convert pkcs7 into DER */
>>> +	ctx->sig_data = NULL;
>>> +	ctx->sig_size = ASN1_item_i2d((ASN1_VALUE *)p7, &ctx->sig_data,
>>> +				      ASN1_ITEM_rptr(PKCS7));
>>> +	if (!ctx->sig_size)
>>> +		goto err;
>>> +
>>> +	/* fill auth_info */
>>> +	ctx->auth.auth_info.hdr.dwLength = sizeof(ctx->auth.auth_info)
>>> +						+ ctx->sig_size;
>>> +	ctx->auth.auth_info.hdr.wRevision = WIN_CERT_REVISION_2_0;
>>> +	ctx->auth.auth_info.hdr.wCertificateType = WIN_CERT_TYPE_EFI_GUID;
>>> +	memcpy(&ctx->auth.auth_info.cert_type, &efi_guid_cert_type_pkcs7,
>>> +	       sizeof(efi_guid_cert_type_pkcs7));
>>> +
>>> +	ret = 0;
>>> +err:
>>> +	BIO_free_all(data_bio);
>>> +	EVP_PKEY_free(key);
>>> +	X509_free(cert);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int dump_signature(const char *path, u8 *signature, size_t sig_size)
>>> +{
>>> +	char *sig_path;
>>> +	FILE *f;
>>> +	size_t size;
>>> +	int ret = -1;
>>> +
>>> +	sig_path = malloc(strlen(path) + 3 + 1);
>>> +	if (!sig_path)
>>> +		return ret;
>>> +
>>> +	sprintf(sig_path, "%s.p7", path);
>>> +	f = fopen(sig_path, "w");
>>> +	if (!f)
>>> +		goto err;
>>> +
>>> +	size = fwrite(signature, 1, sig_size, f);
>>> +	if (size == sig_size)
>>> +		ret = 0;
>>> +
>>> +	fclose(f);
>>> +err:
>>> +	free(sig_path);
>>> +	return ret;
>>> +}
>>> +
>>> +static void free_sig_data(struct auth_context *ctx)
>>> +{
>>> +	if (ctx->sig_size)
>>> +		OPENSSL_free(ctx->sig_data);
>>> +}
>>> +#else
>>> +static int create_auth_data(struct auth_context *ctx)
>>> +{
>>> +	return 0;
>>> +}
>>> +
>>> +static int dump_signature(const char *path, u8 *signature, size_t sig_size)
>>> +{
>>> +	return 0;
>>> +}
>>> +
>>> +static void free_sig_data(struct auth_context *ctx) {}
>>> +#endif
>>> +
>>>    static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
>>> -			unsigned long index, unsigned long instance)
>>> +			unsigned long index, unsigned long instance,
>>> +			uint64_t mcount, char *privkey_file, char *cert_file)
>>>    {
>>>    	struct efi_capsule_header header;
>>>    	struct efi_firmware_management_capsule_header capsule;
>>>    	struct efi_firmware_management_capsule_image_header image;
>>> +	struct auth_context auth_context;
>>>    	FILE *f, *g;
>>>    	struct stat bin_stat;
>>>    	u8 *data;
>>> @@ -78,6 +280,7 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
>>>    	printf("\tbin: %s\n\ttype: %pUl\n", bin, guid);
>>>    	printf("\tindex: %ld\n\tinstance: %ld\n", index, instance);
>>
>> [tools/mkeficapsule.c:281] (warning) %ld in format string (no. 1)
>> requires 'long' but the argument type is 'unsigned long'.
>
> Will fix it.
>
> -Takahiro Akashi
>
>
>> Best regards
>>
>> Heinrich
>>
>>>    #endif
>>> +	auth_context.sig_size = 0;
>>>
>>>    	g = fopen(bin, "r");
>>>    	if (!g) {
>>> @@ -93,11 +296,34 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
>>>    		printf("cannot allocate memory: %zx\n", (size_t)bin_stat.st_size);
>>>    		goto err_1;
>>>    	}
>>> -	f = fopen(path, "w");
>>> -	if (!f) {
>>> -		printf("cannot open %s\n", path);
>>> +
>>> +	size = fread(data, 1, bin_stat.st_size, g);
>>> +	if (size < bin_stat.st_size) {
>>> +		printf("read failed (%zx)\n", size);
>>>    		goto err_2;
>>>    	}
>>> +
>>> +	/* first, calculate signature to determine its size */
>>> +	if (privkey_file && cert_file) {
>>> +		auth_context.key_file = privkey_file;
>>> +		auth_context.cert_file = cert_file;
>>> +		auth_context.auth.monotonic_count = mcount;
>>> +		auth_context.image_data = data;
>>> +		auth_context.image_size = bin_stat.st_size;
>>> +
>>> +		if (create_auth_data(&auth_context)) {
>>> +			printf("Signing firmware image failed\n");
>>> +			goto err_3;
>>> +		}
>>> +
>>> +		if (dump_sig &&
>>> +		    dump_signature(path, auth_context.sig_data,
>>> +				   auth_context.sig_size)) {
>>> +			printf("Creating signature file failed\n");
>>> +			goto err_3;
>>> +		}
>>> +	}
>>> +
>>>    	header.capsule_guid = efi_guid_fm_capsule;
>>>    	header.header_size = sizeof(header);
>>>    	/* TODO: The current implementation ignores flags */
>>> @@ -106,11 +332,20 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
>>>    					+ sizeof(capsule) + sizeof(u64)
>>>    					+ sizeof(image)
>>>    					+ bin_stat.st_size;
>>> +	if (auth_context.sig_size)
>>> +		header.capsule_image_size += sizeof(auth_context.auth)
>>> +				+ auth_context.sig_size;
>>> +
>>> +	f = fopen(path, "w");
>>> +	if (!f) {
>>> +		printf("cannot open %s\n", path);
>>> +		goto err_3;
>>> +	}
>>>
>>>    	size = fwrite(&header, 1, sizeof(header), f);
>>>    	if (size < sizeof(header)) {
>>>    		printf("write failed (%zx)\n", size);
>>> -		goto err_3;
>>> +		goto err_4;
>>>    	}
>>>
>>>    	capsule.version = 0x00000001;
>>> @@ -119,13 +354,13 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
>>>    	size = fwrite(&capsule, 1, sizeof(capsule), f);
>>>    	if (size < (sizeof(capsule))) {
>>>    		printf("write failed (%zx)\n", size);
>>> -		goto err_3;
>>> +		goto err_4;
>>>    	}
>>>    	offset = sizeof(capsule) + sizeof(u64);
>>>    	size = fwrite(&offset, 1, sizeof(offset), f);
>>>    	if (size < sizeof(offset)) {
>>>    		printf("write failed (%zx)\n", size);
>>> -		goto err_3;
>>> +		goto err_4;
>>>    	}
>>>
>>>    	image.version = 0x00000003;
>>> @@ -135,34 +370,53 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
>>>    	image.reserved[1] = 0;
>>>    	image.reserved[2] = 0;
>>>    	image.update_image_size = bin_stat.st_size;
>>> +	if (auth_context.sig_size)
>>> +		image.update_image_size += sizeof(auth_context.auth)
>>> +				+ auth_context.sig_size;
>>>    	image.update_vendor_code_size = 0; /* none */
>>>    	image.update_hardware_instance = instance;
>>>    	image.image_capsule_support = 0;
>>> +	if (auth_context.sig_size)
>>> +		image.image_capsule_support |= CAPSULE_SUPPORT_AUTHENTICATION;
>>>
>>>    	size = fwrite(&image, 1, sizeof(image), f);
>>>    	if (size < sizeof(image)) {
>>>    		printf("write failed (%zx)\n", size);
>>> -		goto err_3;
>>> +		goto err_4;
>>>    	}
>>> -	size = fread(data, 1, bin_stat.st_size, g);
>>> -	if (size < bin_stat.st_size) {
>>> -		printf("read failed (%zx)\n", size);
>>> -		goto err_3;
>>> +
>>> +	if (auth_context.sig_size) {
>>> +		size = fwrite(&auth_context.auth, 1,
>>> +			      sizeof(auth_context.auth), f);
>>> +		if (size < sizeof(auth_context.auth)) {
>>> +			printf("write failed (%zx)\n", size);
>>> +			goto err_4;
>>> +		}
>>> +		size = fwrite(auth_context.sig_data, 1,
>>> +			      auth_context.sig_size, f);
>>> +		if (size < auth_context.sig_size) {
>>> +			printf("write failed (%zx)\n", size);
>>> +			goto err_4;
>>> +		}
>>>    	}
>>> +
>>>    	size = fwrite(data, 1, bin_stat.st_size, f);
>>>    	if (size < bin_stat.st_size) {
>>>    		printf("write failed (%zx)\n", size);
>>> -		goto err_3;
>>> +		goto err_4;
>>>    	}
>>>
>>>    	fclose(f);
>>>    	fclose(g);
>>>    	free(data);
>>> +	free_sig_data(&auth_context);
>>>
>>>    	return 0;
>>>
>>> -err_3:
>>> +err_4:
>>>    	fclose(f);
>>> +err_3:
>>> +	free_sig_data(&auth_context);
>>>    err_2:
>>>    	free(data);
>>>    err_1:
>>> @@ -171,23 +425,25 @@ err_1:
>>>    	return -1;
>>>    }
>>>
>>> -/*
>>> - * Usage:
>>> - *   $ mkeficapsule -f <firmware binary> <output file>
>>> - */
>>>    int main(int argc, char **argv)
>>>    {
>>>    	char *file;
>>>    	efi_guid_t *guid;
>>>    	unsigned long index, instance;
>>> +	uint64_t mcount;
>>> +	char *privkey_file, *cert_file;
>>>    	int c, idx;
>>>
>>>    	file = NULL;
>>>    	guid = NULL;
>>>    	index = 0;
>>>    	instance = 0;
>>> +	mcount = 0;
>>> +	privkey_file = NULL;
>>> +	cert_file = NULL;
>>> +	dump_sig = 0;
>>>    	for (;;) {
>>> -		c = getopt_long(argc, argv, "f:r:i:I:v:h", options, &idx);
>>> +		c = getopt_long(argc, argv, opts_short, options, &idx);
>>>    		if (c == -1)
>>>    			break;
>>>
>>> @@ -214,26 +470,44 @@ int main(int argc, char **argv)
>>>    		case 'I':
>>>    			instance = strtoul(optarg, NULL, 0);
>>>    			break;
>>> +#ifdef CONFIG_TOOLS_LIBCRYPTO
>>> +		case 'p':
>>> +			if (privkey_file) {
>>> +				printf("Private Key already specified\n");
>>> +				return -1;
>>> +			}
>>> +			privkey_file = optarg;
>>> +			break;
>>> +		case 'c':
>>> +			if (cert_file) {
>>> +				printf("Certificate file already specified\n");
>>> +				return -1;
>>> +			}
>>> +			cert_file = optarg;
>>> +			break;
>>> +		case 'm':
>>> +			mcount = strtoul(optarg, NULL, 0);
>>> +			break;
>>> +		case 'd':
>>> +			dump_sig = 1;
>>> +			break;
>>> +#endif /* CONFIG_TOOLS_LIBCRYPTO */
>>>    		case 'h':
>>>    			print_usage();
>>>    			return 0;
>>>    		}
>>>    	}
>>>
>>> -	/* need an output file */
>>> -	if (argc != optind + 1) {
>>> +	/* check necessary parameters */
>>> +	if ((argc != optind + 1) || !file ||
>>> +	    ((privkey_file && !cert_file) ||
>>> +	     (!privkey_file && cert_file))) {
>>>    		print_usage();
>>>    		exit(EXIT_FAILURE);
>>>    	}
>>>
>>> -	/* need a fit image file or raw image file */
>>> -	if (!file) {
>>> -		print_usage();
>>> -		exit(EXIT_SUCCESS);
>>> -	}
>>> -
>>> -	if (create_fwbin(argv[optind], file, guid, index, instance)
>>> -			< 0) {
>>> +	if (create_fwbin(argv[optind], file, guid, index, instance,
>>> +			 mcount, privkey_file, cert_file) < 0) {
>>>    		printf("Creating firmware capsule failed\n");
>>>    		exit(EXIT_FAILURE);
>>>    	}
>>>
>>


More information about the U-Boot mailing list