[PATCH 1/4] tools: mkeficapsule: add firmwware image signing

Heinrich Schuchardt
2021-05-13T04:22:39Z

On 5/13/21 5:08 AM, AKASHI Takahiro wrote:
> On Wed, May 12, 2021 at 10:56:41AM +0200, Heinrich Schuchardt wrote:
>> On 12.05.21 06:57, AKASHI Takahiro wrote:
>>> With this enhancement, mkeficapsule will be able to create a capsule
>>> file with a signature which will be verified later by FMP's SetImage().
>>>
>>> We will have to specify addtional command parameters:
>>> -monotonic-cout <count> : monotonic count
>>> -private-key <private key file> : private key file
>>> -certificate <certificate file> : certificate file
>>> Only when those parameters are given, a signature will be added
>>> to a capsule file.
>>>
>>> Users are expected to maintain the monotonic count for each firmware
>>> image.
>>>
>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>>> ---
>>> tools/Makefile | 4 +
>>> tools/mkeficapsule.c | 324 +++++++++++++++++++++++++++++++++++++++----
>>> 2 files changed, 303 insertions(+), 25 deletions(-)
>>>
>>> diff --git a/tools/Makefile b/tools/Makefile
>>> index d020c55d6644..02eae0286e20 100644
>>> --- a/tools/Makefile
>>> +++ b/tools/Makefile
>>> @@ -231,6 +231,10 @@ hostprogs-$(CONFIG_MIPS) += mips-relocs
>>> hostprogs-$(CONFIG_ASN1_COMPILER) += asn1_compiler
>>> HOSTCFLAGS_asn1_compiler.o = -idirafter $(srctree)/include
>>>
>>> +ifneq ($(CONFIG_EFI_CAPSULE_AUTHENTICATE),)
>>> +HOSTLDLIBS_mkeficapsule += \
>>> + $(shell pkg-config --libs libssl libcrypto 2> /dev/null || echo "-lssl -lcrypto")
>>
>> I don't expect any user wants to install two tool versions in parallel.
>>
>> The tool should always be able to add a signature.
>> Adding a signature must be optional.
>
> It seems to me that those two statements mutually contradict.
> Or do you intend to say that we should have a separate kconfig
> option to enable/disable signing feature in mkeficapsule?
>
> If so, I can agree.
>
> In either way, we should have an option to turn on/off this functionality
> as not all users use signed capsules.

I want to have a single binary to distribute with Linux distros (e.g.
Debian/Ubuntu package u-boot-tools).

This should allow both

- create signed capsules
- create unsigned capsules

The user shall select signing via command line parameters.

Support for signing via the tool shall not depend on board Kconfig
parameters.

Best regards

Heinrich

>
>>> +endif
>>> mkeficapsule-objs := mkeficapsule.o $(LIBFDT_OBJS)
>>> hostprogs-$(CONFIG_EFI_HAVE_CAPSULE_SUPPORT) += mkeficapsule
>>>
>>> diff --git a/tools/mkeficapsule.c b/tools/mkeficapsule.c
>>> index de0a62898886..34ff1bdd82eb 100644
>>> --- a/tools/mkeficapsule.c
>>> +++ b/tools/mkeficapsule.c
>>> @@ -18,7 +18,17 @@
>>> #include <sys/stat.h>
>>> #include <sys/types.h>
>>>
>>> -#include "fdt_host.h"
>>> +#include <linux/kconfig.h>
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> see above
>>
>>> +#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
>>> +
>>> +#include <linux/libfdt.h>
>>>
>>> typedef __u8 u8;
>>> typedef __u16 u16;
>>> @@ -46,6 +56,13 @@ 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;
>>> +
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> see above
>>
>>> +static const char *opts_short = "f:r:i:I:v:D:K:P:C:m:dOh";
>>> +#else
>>> +static const char *opts_short = "f:r:i:I:v:D:K:Oh";
>>> +#endif
>>>
>>> static struct option options[] = {
>>> {"fit", required_argument, NULL, 'f'},
>>> @@ -54,6 +71,12 @@ static struct option options[] = {
>>> {"instance", required_argument, NULL, 'I'},
>>> {"dtb", required_argument, NULL, 'D'},
>>> {"public key", required_argument, NULL, 'K'},
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>> + {"private-key", required_argument, NULL, 'P'},
>>> + {"certificate", required_argument, NULL, 'C'},
>>> + {"monotonic-count", required_argument, NULL, 'm'},
>>
>> These options should not be required.
>
> I don't get you. What do you mean?
>
>>> + {"dump-sig", no_argument, NULL, 'd'},
>>> +#endif
>>> {"overlay", no_argument, NULL, 'O'},
>>> {"help", no_argument, NULL, 'h'},
>>> {NULL, 0, NULL, 0},
>>> @@ -70,6 +93,12 @@ static void print_usage(void)
>>> "\t-I, --instance <instance> update hardware instance\n"
>>> "\t-K, --public-key <key file> public key esl file\n"
>>> "\t-D, --dtb <dtb file> dtb file\n"
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> see above
>>
>>> + "\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-O, --overlay the dtb file is an overlay\n"
>>> "\t-h, --help print a help message\n",
>>> tool_name);
>>> @@ -249,12 +278,167 @@ err:
>>> return ret;
>>> }
>>>
>>> +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;
>>> +
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> see above
>>
>>> +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);
>>
>> Please, you use fprintf(stderr,) for error messages.
>>
>>> + ERR_print_errors_fp(stderr);
>>> + }
>>> +
>>> + return key;
>>> +}
>>> +
>>> +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);
>>
>> fprintf(stderr,)
>>
>>> + 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 */
>>
>> PKCS7_NOATTR is a value without any documentation in the code.
>
> Nak.
> Those macros are part of openssl library. See openssl/pkcs7.h.
>
>> Please, replace variable names by a long text describing what it missing.
>>
>>> + flags = PKCS7_BINARY | PKCS7_DETACHED;
>>
>> Those constants lack documentation in the code.
>
> Nak again.
>
>>> + 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;
>>> +}
>>> +#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;
>>> @@ -266,6 +450,7 @@ 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);
>>> #endif
>>> + auth_context.sig_size = 0;
>>>
>>> g = fopen(bin, "r");
>>> if (!g) {
>>> @@ -281,11 +466,36 @@ 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 IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> see above
>>
>>> + 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;
>>> + }
>>> + }
>>> +#endif
>>> +
>>> header.capsule_guid = efi_guid_fm_capsule;
>>> header.header_size = sizeof(header);
>>> /* TODO: The current implementation ignores flags */
>>> @@ -294,11 +504,20 @@ 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;
>>> @@ -307,13 +526,13 @@ 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;
>>> @@ -323,34 +542,61 @@ 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 IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> We don't want to use #if if avoidable.
>
> For this specific chunk of code, we can remove #ifdef,
> but we should not remove #ifdef elsewhere.
>
> -Takahiro Akashi
>
>
>>> + 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;
>>> + }
>>> }
>>> +#endif
>>> +
>>> 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);
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>> + if (auth_context.sig_size)
>>> + OPENSSL_free(auth_context.sig_data);
>>> +#endif
>>>
>>> return 0;
>>>
>>> -err_3:
>>> +err_4:
>>> fclose(f);
>>> +err_3:
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>> + if (auth_context.sig_size)
>>> + OPENSSL_free(auth_context.sig_data);
>>> +#endif
>>> err_2:
>>> free(data);
>>> err_1:
>>> @@ -359,10 +605,6 @@ err_1:
>>> return -1;
>>> }
>>>
>>> -/*
>>> - * Usage:
>>> - * $ mkeficapsule -f <firmware binary>
>>> - */
>>> int main(int argc, char **argv)
>>> {
>>> char *file;
>>> @@ -370,6 +612,8 @@ int main(int argc, char **argv)
>>> char *dtb_file;
>>> efi_guid_t *guid;
>>> unsigned long index, instance;
>>> + uint64_t mcount;
>>> + char *privkey_file, *cert_file;
>>> int c, idx;
>>> int ret;
>>> bool overlay = false;
>>> @@ -380,8 +624,12 @@ int main(int argc, char **argv)
>>> 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:D:K:Oh", options, &idx);
>>> + c = getopt_long(argc, argv, opts_short, options, &idx);
>>> if (c == -1)
>>> break;
>>>
>>> @@ -422,6 +670,28 @@ int main(int argc, char **argv)
>>> }
>>> dtb_file = optarg;
>>> break;
>>> +#if IS_ENABLED(CONFIG_EFI_CAPSULE_AUTHENTICATE)
>>
>> see above
>>
>> Best regards
>>
>> Heinrich
>>
>>> + 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
>>> case 'O':
>>> overlay = true;
>>> break;
>>> @@ -431,8 +701,12 @@ int main(int argc, char **argv)
>>> }
>>> }
>>>
>>> - /* need a fit image file or raw image file */
>>> - if (!file && !pkey_file && !dtb_file) {
>>> + /* check necessary parameters */
>>> + if ((file && (!(optind < argc) ||
>>> + (privkey_file && !cert_file) ||
>>> + (!privkey_file && cert_file))) ||
>>> + ((pkey_file && !dtb_file) ||
>>> + (!pkey_file && dtb_file))) {
>>> print_usage();
>>> exit(EXIT_FAILURE);
>>> }
>>> @@ -442,12 +716,12 @@ int main(int argc, char **argv)
>>> if (ret == -1) {
>>> printf("Adding public key to the dtb failed\n");
>>> exit(EXIT_FAILURE);
>>> - } else {
>>> - exit(EXIT_SUCCESS);
>>> }
>>> }
>>>
>>> - if (create_fwbin(argv[optind], file, guid, index, instance)
>>> + if (optind < argc &&
>>> + create_fwbin(argv[optind], file, guid, index, instance,
>>> + mcount, privkey_file, cert_file)
>>> < 0) {
>>> printf("Creating firmware capsule failed\n");
>>> exit(EXIT_FAILURE);
>>>
>>