Re: [PATCH v6 03/12] tools: mkeficapsule: add firmwware image signing

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Sun, Nov 07, 2021 at 07:53:24AM +0100, Heinrich Schuchardt wrote:
> On 11/2/21 01:55, 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@linaro.org>
> > Reviewed-by: Simon Glass <sjg@chromium.org>
> 
> You licensed tools/mkeficapsule.c under GPL-2.0 which is imcompatible
> with OpenSSL (https://www.gnu.org/licenses/license-list.html#OpenSSL).

In fact, this is not a this-tool-specific issue, but other tools,
including mkimage, have it and that is why CONFIG_TOOLS_LIBCRYPTO was
introduced.

# I think that I have mentioned the issue in my past comment.

-Takahiro Akashi


> Either agree with all contributors of the tool to use a more liberal
> license or use another library.
> 
> > ---
> >   tools/Kconfig        |   8 +
> >   tools/Makefile       |   8 +-
> >   tools/mkeficapsule.c | 382 ++++++++++++++++++++++++++++++++++++++++---
> >   3 files changed, 376 insertions(+), 22 deletions(-)
> > 
> > diff --git a/tools/Kconfig b/tools/Kconfig
> > index 91ce8ae3e516..117c921da3fe 100644
> > --- a/tools/Kconfig
> > +++ b/tools/Kconfig
> > @@ -90,4 +90,12 @@ config TOOLS_SHA512
> >   	help
> >   	  Enable SHA512 support in the tools builds
> > 
> > +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 b45219e2c30c..5a73cc4b363d 100644
> > --- a/tools/Makefile
> > +++ b/tools/Makefile
> > @@ -238,8 +238,12 @@ 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 += \
> > +	$(shell pkg-config --libs libssl libcrypto 2> /dev/null || echo "-lssl -lcrypto")
> > +endif
> > +hostprogs-$(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 8427fedd941c..086757ee8ad7 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},
> >   };
> > @@ -57,10 +80,252 @@ 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);
> >   }
> > 
> > +/**
> > + * auth_context - authentication context
> > + * @key_file:	Path to a private key file
> > + * @cert_file:	Path to a certificate file
> > + * @image_data:	Pointer to firmware data
> > + * @image_size:	Size of firmware data
> > + * @auth:	Authentication header
> > + * @sig_data:	Signature data
> > + * @sig_size:	Size of signature data
> > + *
> > + * Data structure used in create_auth_data(). @key_file through
> > + * @image_size are input parameters. @auth, @sig_data and @sig_size
> > + * are filled in by create_auth_data().
> > + */
> > +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
> > +/**
> > + * fileio-read_pkey - read out a private key
> > + * @filename:	Path to a private key file
> > + *
> > + * Read out a private key file and parse it into "EVP_PKEY" structure.
> > + *
> > + * Return:
> > + * * Pointer to private key structure  - on success
> > + * * NULL - on failure
> > + */
> > +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;
> > +}
> > +
> > +/**
> > + * fileio-read_cert - read out a certificate
> > + * @filename:	Path to a certificate file
> > + *
> > + * Read out a certificate file and parse it into "X509" structure.
> > + *
> > + * Return:
> > + * * Pointer to certificate structure  - on success
> > + * * NULL - on failure
> > + */
> > +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;
> > +}
> > +
> > +/**
> > + * create_auth_data - compose authentication data in capsule
> > + * @auth_context:	Pointer to authentication context
> > + *
> > + * Fill up an authentication header (.auth) and signature data (.sig_data)
> > + * in @auth_context, using library functions from openssl.
> > + * All the parameters in @auth_context must be filled in by a caller.
> > + *
> > + * Return:
> > + * * 0  - on success
> > + * * -1 - on failure
> > + */
> > +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;
> > +}
> > +
> > +/**
> > + * dump_signature - dump out a signature
> > + * @path:	Path to a capsule file
> > + * @signature:	Signature data
> > + * @sig_size:	Size of signature data
> > + *
> > + * Signature data pointed to by @signature will be saved into
> > + * a file whose file name is @path with ".p7" suffix.
> > + *
> > + * Return:
> > + * * 0  - on success
> > + * * -1 - on failure
> > + */
> > +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;
> > +}
> > +
> > +/**
> > + * free_sig_data - free out signature data
> > + * @ctx:	Pointer to authentication context
> > + *
> > + * Free signature data allocated in create_auth_data().
> > + */
> > +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
> > +
> >   /**
> >    * read_bin_file - read a firmware binary file
> >    * @bin:	Path to a firmware binary file
> > @@ -162,11 +427,13 @@ static int write_capsule_file(FILE *f, void *data, size_t size, const char *msg)
> >    * * -1 - on failure
> >    */
> >   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;
> >   	void *data;
> >   	off_t bin_size;
> > @@ -176,9 +443,9 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
> >   #ifdef DEBUG
> 
> scripts/checkpatch.pl gives the following warning for this file:
> 
> Use 'if (IS_ENABLED(CONFIG...))' instead of '#if or #ifdef' where possible.
> 
> Best regards
> 
> Heinrich
> 
> >   	printf("For output: %s\n", path);
> >   	printf("\tbin: %s\n\ttype: %pUl\n", bin, guid);
> > -	printf("\tindex: %ld\n\tinstance: %ld\n", index, instance);
> > +	printf("\tindex: %lu\n\tinstance: %lu\n", index, instance);
> >   #endif
> > -
> > +	auth_context.sig_size = 0;
> >   	f = NULL;
> >   	data = NULL;
> >   	ret = -1;
> > @@ -189,6 +456,27 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
> >   	if (read_bin_file(bin, &data, &bin_size))
> >   		goto err;
> > 
> > +	/* 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_size;
> > +
> > +		if (create_auth_data(&auth_context)) {
> > +			printf("Signing firmware image failed\n");
> > +			goto err;
> > +		}
> > +
> > +		if (dump_sig &&
> > +		    dump_signature(path, auth_context.sig_data,
> > +				   auth_context.sig_size)) {
> > +			printf("Creating signature file failed\n");
> > +			goto err;
> > +		}
> > +	}
> > +
> >   	/*
> >   	 * write a capsule file
> >   	 */
> > @@ -209,6 +497,9 @@ static int create_fwbin(char *path, char *bin, efi_guid_t *guid,
> >   					+ sizeof(capsule) + sizeof(u64)
> >   					+ sizeof(image)
> >   					+ bin_size;
> > +	if (auth_context.sig_size)
> > +		header.capsule_image_size += sizeof(auth_context.auth)
> > +				+ auth_context.sig_size;
> >   	if (write_capsule_file(f, &header, sizeof(header),
> >   			       "Capsule header"))
> >   		goto err;
> > @@ -239,13 +530,32 @@ 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_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;
> >   	if (write_capsule_file(f, &image, sizeof(image),
> >   			       "Firmware capsule image header"))
> >   		goto err;
> > 
> > +	/*
> > +	 * signature
> > +	 */
> > +	if (auth_context.sig_size) {
> > +		if (write_capsule_file(f, &auth_context.auth,
> > +				       sizeof(auth_context.auth),
> > +				       "Authentication header"))
> > +			goto err;
> > +
> > +		if (write_capsule_file(f, auth_context.sig_data,
> > +				       auth_context.sig_size, "Signature"))
> > +			goto err;
> > +	}
> > +
> >   	/*
> >   	 * firmware binary
> >   	 */
> > @@ -262,23 +572,37 @@ err:
> >   	return ret;
> >   }
> > 
> > -/*
> > - * Usage:
> > - *   $ mkeficapsule -f <firmware binary> <output file>
> > +/**
> > + * main - main entry function of mkeficapsule
> > + * @argc:	Number of arguments
> > + * @argv:	Array of pointers to arguments
> > + *
> > + * Create an uefi capsule file, optionally signing it.
> > + * Parse all the arguments and pass them on to create_fwbin().
> > + *
> > + * Return:
> > + * * 0  - on success
> > + * * -1 - on failure
> >    */
> >   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;
> > 
> > @@ -286,7 +610,7 @@ int main(int argc, char **argv)
> >   		case 'f':
> >   			if (file) {
> >   				printf("Image already specified\n");
> > -				return -1;
> > +				exit(EXIT_FAILURE);
> >   			}
> >   			file = optarg;
> >   			guid = &efi_guid_image_type_uboot_fit;
> > @@ -294,7 +618,7 @@ int main(int argc, char **argv)
> >   		case 'r':
> >   			if (file) {
> >   				printf("Image already specified\n");
> > -				return -1;
> > +				exit(EXIT_FAILURE);
> >   			}
> >   			file = optarg;
> >   			guid = &efi_guid_image_type_uboot_raw;
> > @@ -305,26 +629,44 @@ 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");
> > +				exit(EXIT_FAILURE);
> > +			}
> > +			privkey_file = optarg;
> > +			break;
> > +		case 'c':
> > +			if (cert_file) {
> > +				printf("Certificate file already specified\n");
> > +				exit(EXIT_FAILURE);
> > +			}
> > +			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;
> > +			exit(EXIT_SUCCESS);
> >   		}
> >   	}
> > 
> > -	/* 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);
> >   	}
> >