[PATCH v6 03/12] tools: mkeficapsule: add firmwware image signing
AKASHI Takahiro
takahiro.akashi at linaro.org
Tue Nov 2 01:55:03 CET 2021
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>
Reviewed-by: Simon Glass <sjg at chromium.org>
---
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
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);
}
--
2.33.0
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