Re: [PATCH v5 11/23] mkeficapsule: Add support for generating empty capsules

Etienne Carriere
2022-06-21T10:58:33Z

On Thu, 9 Jun 2022 at 14:31, Sughosh Ganu <sughosh.ganu@linaro.org> wrote:
>
> The Dependable Boot specification[1] describes the structure of the
> firmware accept and revert capsules. These are empty capsules which
> are used for signalling the acceptance or rejection of the updated
> firmware by the OS. Add support for generating these empty capsules.
>
> [1] - https://git.codelinaro.org/linaro/dependable-boot/mbfw/uploads/6f7ddfe3be24e18d4319e108a758d02e/mbfw.pdf
>
> Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
> ---
> doc/mkeficapsule.1 | 29 ++++++---
> tools/eficapsule.h | 8 +++
> tools/mkeficapsule.c | 139 +++++++++++++++++++++++++++++++++++++------
> 3 files changed, 151 insertions(+), 25 deletions(-)
>
> diff --git a/doc/mkeficapsule.1 b/doc/mkeficapsule.1
> index 09bdc24295..77ca061efd 100644
> --- a/doc/mkeficapsule.1
> +++ b/doc/mkeficapsule.1
> @@ -8,7 +8,7 @@ mkeficapsule \- Generate EFI capsule file for U-Boot
>
> .SH SYNOPSIS
> .B mkeficapsule
> -.RI [ options "] " image-blob " " capsule-file
> +.RI [ options ] " " [ image-blob ] " " capsule-file
>
> .SH "DESCRIPTION"
> .B mkeficapsule
> @@ -23,8 +23,13 @@ Optionally, a capsule file can be signed with a given private key.
> In this case, the update will be authenticated by verifying the signature
> before applying.
>
> +Additionally, an empty capsule file can be generated for acceptance or
> +rejection of firmware images by a governing component like an Operating
> +System. The empty capsules do not require an image-blob input file.
> +
> +
> .B mkeficapsule
> -takes any type of image files, including:
> +takes any type of image files when generating non empty capsules, including:
> .TP
> .I raw image
> format is a single binary blob of any type of firmware.
> @@ -36,18 +41,16 @@ multiple binary blobs in a single capsule file.
> This type of image file can be generated by
> .BR mkimage .
>
> -.PP
> -If you want to use other types than above two, you should explicitly
> -specify a guid for the FMP driver.
> -
> .SH "OPTIONS"
> +
> .TP
> .BI "-g\fR,\fB --guid " guid-string
> Specify guid for image blob type. The format is:
> xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
>
> The first three elements are in little endian, while the rest
> -is in big endian.
> +is in big endian. The option must be specified for all non empty and
> +image acceptance capsules
>
> .TP
> .BI "-i\fR,\fB --index " index
> @@ -57,6 +60,18 @@ Specify an image index
> .BI "-I\fR,\fB --instance " instance
> Specify a hardware instance
>
> +.PP
> +For generation of firmware accept empty capsule
> +.BR --guid
> +is mandatory
> +.TP
> +.BI "-A\fR,\fB --fw-accept "
> +Generate a firmware acceptance empty capsule
> +
> +.TP
> +.BI "-R\fR,\fB --fw-revert "
> +Generate a firmware revert empty capsule
> +
> .TP
> .BR -h ", " --help
> Print a help message
> diff --git a/tools/eficapsule.h b/tools/eficapsule.h
> index d63b831443..072a4b5598 100644
> --- a/tools/eficapsule.h
> +++ b/tools/eficapsule.h
> @@ -41,6 +41,14 @@ typedef struct {
> EFI_GUID(0x4aafd29d, 0x68df, 0x49ee, 0x8a, 0xa9, \
> 0x34, 0x7d, 0x37, 0x56, 0x65, 0xa7)
>
> +#define FW_ACCEPT_OS_GUID \
> + EFI_GUID(0x0c996046, 0xbcc0, 0x4d04, 0x85, 0xec, \
> + 0xe1, 0xfc, 0xed, 0xf1, 0xc6, 0xf8)
> +
> +#define FW_REVERT_OS_GUID \
> + EFI_GUID(0xacd58b4b, 0xc0e8, 0x475f, 0x99, 0xb5, \
> + 0x6b, 0x3f, 0x7e, 0x07, 0xaa, 0xf0)
> +
> /* flags */
> #define CAPSULE_FLAGS_PERSIST_ACROSS_RESET 0x00010000
>
> diff --git a/tools/mkeficapsule.c b/tools/mkeficapsule.c
> index 5f74d23b9e..e8eb6b070d 100644
> --- a/tools/mkeficapsule.c
> +++ b/tools/mkeficapsule.c
> @@ -29,7 +29,16 @@ static const char *tool_name = "mkeficapsule";
> efi_guid_t efi_guid_fm_capsule = EFI_FIRMWARE_MANAGEMENT_CAPSULE_ID_GUID;
> efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
>
> -static const char *opts_short = "g:i:I:v:p:c:m:dh";
> +static const char *opts_short = "g:i:I:v:p:c:m:dhAR";
> +
> +static bool empty_capsule;
> +static unsigned char capsule;

Local function create_fwbin() defines a local variable with that same label.
Should be ok to remove this 'capsule' variable if only using
'capsule_type' as suggested by Takahiro-san.

> +
> +enum {
> + CAPSULE_NORMAL_BLOB = 0,
> + CAPSULE_ACCEPT,
> + CAPSULE_REVERT,
> +} capsule_type;
>
> static struct option options[] = {
> {"guid", required_argument, NULL, 'g'},
> @@ -39,24 +48,47 @@ static struct option options[] = {
> {"certificate", required_argument, NULL, 'c'},
> {"monotonic-count", required_argument, NULL, 'm'},
> {"dump-sig", no_argument, NULL, 'd'},
> + {"fw-accept", no_argument, NULL, 'A'},
> + {"fw-revert", no_argument, NULL, 'R'},
> {"help", no_argument, NULL, 'h'},
> {NULL, 0, NULL, 0},
> };
>
> static void print_usage(void)
> {
> - fprintf(stderr, "Usage: %s [options] <image blob> \n"
> - "Options:\n"
> -
> - "\t-g, --guid <guid string> guid for image blob type\n"
> - "\t-i, --index <index> update image index\n"
> - "\t-I, --instance <instance> update hardware instance\n"
> - "\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"
> - "\t-h, --help print a help message\n",
> - tool_name);
> + if (empty_capsule) {
> + if (capsule == CAPSULE_ACCEPT) {
> + fprintf(stderr, "Usage: %s [options] \n",
> + tool_name);
> + fprintf(stderr, "Options:\n"
> + "\t-A, --fw-accept firmware accept capsule\n"
> + "\t-g, --guid <guid string> guid for image blob type\n"
> + "\t-h, --help print a help message\n"
> + );
> + } else {
> + fprintf(stderr, "Usage: %s [options] \n",
> + tool_name);
> + fprintf(stderr, "Options:\n"
> + "\t-R, --fw-revert firmware revert capsule\n"
> + "\t-h, --help print a help message\n"
> + );
> + }
> + } else {
> + fprintf(stderr, "Usage: %s [options] <image blob> \n"
> + "Options:\n"
> +
> + "\t-g, --guid <guid string> guid for image blob type\n"
> + "\t-i, --index <index> update image index\n"
> + "\t-I, --instance <instance> update hardware instance\n"
> + "\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"
> + "\t-A, --fw-accept firmware accept capsule\n"
> + "\t-R, --fw-revert firmware revert capsule\n"
> + "\t-h, --help print a help message\n",
> + tool_name);
> + }
> }
>
> /**
> @@ -564,6 +596,50 @@ void convert_uuid_to_guid(unsigned char *buf)
> buf[7] = c;
> }
>
> +static int create_empty_capsule(char *path, efi_guid_t *guid, bool fw_accept)
> +{
> + struct efi_capsule_header header;

It would be better to initialize the header to known value, e.g. = { }; here.

> + FILE *f = NULL;
> + int ret = -1;
> + efi_guid_t fw_accept_guid = FW_ACCEPT_OS_GUID;
> + efi_guid_t fw_revert_guid = FW_REVERT_OS_GUID;
> + efi_guid_t payload, capsule_guid;
> +
> + f = fopen(path, "w");
> + if (!f) {
> + fprintf(stderr, "cannot open %s\n", path);
> + goto err;
> + }
> +
> + capsule_guid = fw_accept ? fw_accept_guid : fw_revert_guid;
> +
> + memcpy(&header.capsule_guid, &capsule_guid, sizeof(efi_guid_t));
> + header.header_size = sizeof(header);
> + header.flags = 0;
> +
> + header.capsule_image_size = fw_accept ?
> + sizeof(header) + sizeof(efi_guid_t) : sizeof(header);
> +
> + if (write_capsule_file(f, &header, sizeof(header),
> + "Capsule header"))
> + goto err;
> +
> + if (fw_accept) {
> + memcpy(&payload, guid, sizeof(efi_guid_t));
> + if (write_capsule_file(f, &payload, sizeof(payload),
> + "FW Accept Capsule Payload"))

nitpicking: is payload temp variable needed? could pass guid as argument.

> + goto err;
> + }
> +
> + ret = 0;
> +
> +err:
> + if (f)
> + fclose(f);
> +
> + return ret;
> +}
> +
> /**
> * main - main entry function of mkeficapsule
> * @argc: Number of arguments
> @@ -639,22 +715,49 @@ int main(int argc, char **argv)
> case 'd':
> dump_sig = 1;
> break;
> + case 'A':
> + capsule |= CAPSULE_ACCEPT;
> + break;
> + case 'R':
> + capsule |= CAPSULE_REVERT;
> + break;
> case 'h':
> print_usage();
> exit(EXIT_SUCCESS);
> }
> }
>
> + if (capsule == (CAPSULE_ACCEPT | CAPSULE_REVERT)) {
> + fprintf(stderr,
> + "Select either of Accept or Revert capsule generation\n");
> + exit(EXIT_FAILURE);
> + }
> +
> + empty_capsule = (capsule == CAPSULE_ACCEPT ||
> + capsule == CAPSULE_REVERT);
> +
> /* check necessary parameters */
> - if ((argc != optind + 2) || !guid ||
> - ((privkey_file && !cert_file) ||
> - (!privkey_file && cert_file))) {
> + if ((!empty_capsule &&
> + ((argc != optind + 2) || !guid ||
> + ((privkey_file && !cert_file) ||
> + (!privkey_file && cert_file)))) ||
> + (empty_capsule &&
> + ((argc != optind + 1) ||
> + ((capsule == CAPSULE_ACCEPT) && !guid) ||
> + ((capsule == CAPSULE_REVERT) && guid)))) {
> print_usage();
> exit(EXIT_FAILURE);
> }
>
> - if (create_fwbin(argv[argc - 1], argv[argc - 2], guid, index, instance,
> - mcount, privkey_file, cert_file) < 0) {
> + if (empty_capsule) {
> + if (create_empty_capsule(argv[argc - 1], guid,
> + capsule == CAPSULE_ACCEPT) < 0) {
> + fprintf(stderr, "Creating empty capsule failed\n");
> + exit(EXIT_FAILURE);
> + }
> + } else if (create_fwbin(argv[argc - 1], argv[argc - 2], guid,
> + index, instance, mcount, privkey_file,
> + cert_file) < 0) {
> fprintf(stderr, "Creating firmware capsule failed\n");
> exit(EXIT_FAILURE);
> }
> --
> 2.25.1
>