[PATCH v2 1/4] efi_loader: store firmware version into FmpState variable

Masahisa Kojima masahisa.kojima at linaro.org
Fri Mar 3 05:16:10 CET 2023


On Fri, 3 Mar 2023 at 09:17, Takahiro Akashi <takahiro.akashi at linaro.org> wrote:
>
> On Wed, Mar 01, 2023 at 06:15:19PM +0900, Masahisa Kojima wrote:
> > Firmware version management is not implemented in the current
> > FMP protocol.
> > EDK2 reference implementation capsule generation script inserts
> > the FMP Payload Header right before the payload, it contains the
> > firmware version and lowest supported version.
> >
> > This commit utilizes the FMP Payload Header, read the header and
> > stores the firmware version, lowest supported version,
> > last attempt version and last attempt status into "FmpStateXXXX"
> > EFI non-volatile variable. XXXX indicates the image index,
> > since FMP protocol handles multiple image indexes.
> >
> > This change is compatible with the existing FMP implementation.
> > This change does not mandate the FMP Payload Header.
> > If no FMP Payload Header is found in the capsule file, fw_version,
> > lowest supported version, last attempt version and last attempt
> > status is 0 and this is the same behavior as existing FMP
> > implementation.
> >
> > Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> > ---
> > Changes in v2:
> > - modify indent
> >
> >  lib/efi_loader/efi_firmware.c | 198 ++++++++++++++++++++++++++++++----
> >  1 file changed, 175 insertions(+), 23 deletions(-)
> >
> > diff --git a/lib/efi_loader/efi_firmware.c b/lib/efi_loader/efi_firmware.c
> > index 93e2b01c07..d1afafb052 100644
> > --- a/lib/efi_loader/efi_firmware.c
> > +++ b/lib/efi_loader/efi_firmware.c
> > @@ -10,6 +10,7 @@
> >  #include <charset.h>
> >  #include <dfu.h>
> >  #include <efi_loader.h>
> > +#include <efi_variable.h>
> >  #include <fwu.h>
> >  #include <image.h>
> >  #include <signatures.h>
> > @@ -18,6 +19,12 @@
> >
> >  #define FMP_PAYLOAD_HDR_SIGNATURE    SIGNATURE_32('M', 'S', 'S', '1')
> >
> > +#define EFI_FMP_STATE_GUID \
> > +     EFI_GUID(0x84bed885, 0x193a, 0x403f, 0xa2, 0x78, \
> > +              0xe8, 0x9e, 0x23, 0x8a, 0xd6, 0xe1)
> > +
> > +static const efi_guid_t efi_guid_fmp_state = EFI_FMP_STATE_GUID;
> > +
> >  /**
> >   * struct fmp_payload_header - EDK2 header for the FMP payload
> >   *
> > @@ -36,6 +43,24 @@ struct fmp_payload_header {
> >       u32 lowest_supported_version;
> >  };
> >
> > +/**
> > + * struct fmp_state - fmp firmware update state
> > + *
> > + * This structure describes the state of the firmware update
> > + * through FMP protocol.
> > + *
> > + * @fw_version:                      Firmware versions used
> > + * @lowest_supported_version:        Lowest supported version
> > + * @last_attempt_version:    Last attempt version
> > + * @last_attempt_status:     Last attempt status
> > + */
> > +struct fmp_state {
> > +     u32 fw_version;
> > +     u32 lowest_supported_version;
> > +     u32 last_attempt_version;
> > +     u32 last_attempt_status;
> > +};
> > +
> >  __weak void set_dfu_alt_info(char *interface, char *devstr)
> >  {
> >       env_set("dfu_alt_info", update_info.dfu_string);
> > @@ -182,6 +207,7 @@ static efi_status_t efi_fill_image_desc_array(
> >   * efi_firmware_capsule_authenticate - authenticate the capsule if enabled
> >   * @p_image:         Pointer to new image
> >   * @p_image_size:    Pointer to size of new image
> > + * @state            Pointer to fmp state
> >   *
> >   * Authenticate the capsule if authentication is enabled.
> >   * The image pointer and the image size are updated in case of success.
> > @@ -190,12 +216,11 @@ static efi_status_t efi_fill_image_desc_array(
> >   */
> >  static
> >  efi_status_t efi_firmware_capsule_authenticate(const void **p_image,
> > -                                            efi_uintn_t *p_image_size)
> > +                                            efi_uintn_t *p_image_size,
> > +                                            struct fmp_state *state)
> >  {
> >       const void *image = *p_image;
> >       efi_uintn_t image_size = *p_image_size;
> > -     u32 fmp_hdr_signature;
> > -     struct fmp_payload_header *header;
> >       void *capsule_payload;
> >       efi_status_t status;
> >       efi_uintn_t capsule_payload_size;
> > @@ -209,8 +234,12 @@ efi_status_t efi_firmware_capsule_authenticate(const void **p_image,
> >
> >               if (status == EFI_SECURITY_VIOLATION) {
> >                       printf("Capsule authentication check failed. Aborting update\n");
> > +                     state->last_attempt_status =
> > +                             LAST_ATTEMPT_STATUS_ERROR_AUTH_ERROR;
> >                       return status;
> >               } else if (status != EFI_SUCCESS) {
> > +                     state->last_attempt_status =
> > +                             LAST_ATTEMPT_STATUS_ERROR_UNSUCCESSFUL;
> >                       return status;
> >               }
> >
> > @@ -222,24 +251,124 @@ efi_status_t efi_firmware_capsule_authenticate(const void **p_image,
> >               debug("Updating capsule without authenticating.\n");
> >       }
> >
> > -     fmp_hdr_signature = FMP_PAYLOAD_HDR_SIGNATURE;
> > -     header = (void *)image;
> > +     *p_image = image;
> > +     *p_image_size = image_size;
> > +
> > +     return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > + * efi_firmware_set_fmp_state_var - set FmpStateXXXX variable
> > + * @state:           Pointer to fmp state
> > + * @image_index:     image index
> > + * @updated:         flag to indicate firmware update is successful
> > + *
> > + * Update the FmpStateXXXX variable with the firmware update state.
> > + *
> > + * Return:           status code
> > + */
> > +static
> > +efi_status_t efi_firmware_set_fmp_state_var(struct fmp_state *state, u8 image_index,
> > +                                         bool updated)
> > +{
> > +     u16 varname[13]; /* u"FmpStateXXXX" */
> > +     efi_status_t ret;
> > +     efi_uintn_t size;
> > +     struct fmp_state var_state = { 0 };
> > +
> > +     efi_create_indexed_name(varname, sizeof(varname), "FmpState",
> > +                             image_index);
> > +     size = sizeof(var_state);
> > +     ret = efi_get_variable_int(varname, &efi_guid_fmp_state, NULL, &size,
> > +                                &var_state, NULL);
> > +     if (ret != EFI_SUCCESS && ret != EFI_NOT_FOUND)
> > +             return ret;
> > +
> > +     /*
> > +      * When the capsule update is successful, FmpStateXXXX variable is set
> > +      * according to the fmp payload header information. If there is no fmp payload
> > +      * header in the capsule file, all values are set to 0.
> > +      * When the capsule update fails, only last attempt information of FmpStateXXXX
> > +      * variable is updated, fw_version and lowest_supported_version keep original
> > +      * value or 0(in case no FmpStateXXXX variable found).
> > +      */
> > +     if (updated) {
> > +             var_state.fw_version = state->fw_version;
> > +             var_state.lowest_supported_version = state->lowest_supported_version;
> > +             var_state.last_attempt_version = state->last_attempt_version;
> > +             var_state.last_attempt_status = state->last_attempt_status;
> > +     } else {
> > +             var_state.last_attempt_version = state->last_attempt_version;
> > +             var_state.last_attempt_status = state->last_attempt_status;
> > +     }
> > +
> > +     ret = efi_set_variable_int(varname, &efi_guid_fmp_state,
> > +                                EFI_VARIABLE_NON_VOLATILE |
> > +                                EFI_VARIABLE_BOOTSERVICE_ACCESS |
> > +                                EFI_VARIABLE_RUNTIME_ACCESS,
> > +                                sizeof(var_state), &var_state, false);
>
> One of my concerns about using UEFI variables as a storage for internal data
> like firmwware status is that they are unnecessarily accessible to users.
>
> In this sense, I think that those variable should be *read-only* and
> maintained only by the system.

Yes, this FmpState variable should be read-only.

Thanks,
Masahisa Kojima

>
> -Takahiro Akashi
>
>
> > +     return ret;
> > +}
> >
> > +/**
> > + * efi_firmware_parse_payload_header - parse FMP payload header
> > + * @p_image:         Pointer to new image
> > + * @p_image_size:    Pointer to size of new image
> > + * @state            Pointer to fmp state
> > + *
> > + * Parse the FMP payload header and fill the fmp_state structure.
> > + * If no FMP payload header is found, fmp_state structure is not updated.
> > + *
> > + */
> > +static
> > +void efi_firmware_parse_payload_header(const void **p_image,
> > +                                    efi_uintn_t *p_image_size,
> > +                                    struct fmp_state *state)
> > +{
> > +     const void *image = *p_image;
> > +     efi_uintn_t image_size = *p_image_size;
> > +     const struct fmp_payload_header *header;
> > +     u32 fmp_hdr_signature = FMP_PAYLOAD_HDR_SIGNATURE;
> > +
> > +     header = image;
> >       if (!memcmp(&header->signature, &fmp_hdr_signature,
> >                   sizeof(fmp_hdr_signature))) {
> > -             /*
> > -              * When building the capsule with the scripts in
> > -              * edk2, a FMP header is inserted above the capsule
> > -              * payload. Compensate for this header to get the
> > -              * actual payload that is to be updated.
> > -              */
> > +             /* FMP header is inserted above the capsule payload */
> > +             state->fw_version = header->fw_version;
> > +             state->lowest_supported_version = header->lowest_supported_version;
> > +             state->last_attempt_version = header->fw_version;
> >               image += header->header_size;
> >               image_size -= header->header_size;
> >       }
> >
> >       *p_image = image;
> >       *p_image_size = image_size;
> > -     return EFI_SUCCESS;
> > +}
> > +
> > +/**
> > + * efi_firmware_verify_image - verify image
> > + * @p_image:         Pointer to new image
> > + * @p_image_size:    Pointer to size of new image
> > + * @image_index              Image index
> > + * @state            Pointer to fmp state
> > + *
> > + * Verify the capsule file
> > + *
> > + * Return:           status code
> > + */
> > +static
> > +efi_status_t efi_firmware_verify_image(const void **p_image,
> > +                                    efi_uintn_t *p_image_size,
> > +                                    u8 image_index,
> > +                                    struct fmp_state *state)
> > +{
> > +     efi_status_t ret;
> > +
> > +     ret = efi_firmware_capsule_authenticate(p_image, p_image_size, state);
> > +     efi_firmware_parse_payload_header(p_image, p_image_size, state);
> > +
> > +     return ret;
> >  }
> >
> >  /**
> > @@ -330,7 +459,9 @@ efi_status_t EFIAPI efi_firmware_fit_set_image(
> >       efi_status_t (*progress)(efi_uintn_t completion),
> >       u16 **abort_reason)
> >  {
> > +     bool updated;
> >       efi_status_t status;
> > +     struct fmp_state state = { 0 };
> >
> >       EFI_ENTRY("%p %d %p %zu %p %p %p\n", this, image_index, image,
> >                 image_size, vendor_code, progress, abort_reason);
> > @@ -338,14 +469,22 @@ efi_status_t EFIAPI efi_firmware_fit_set_image(
> >       if (!image || image_index != 1)
> >               return EFI_EXIT(EFI_INVALID_PARAMETER);
> >
> > -     status = efi_firmware_capsule_authenticate(&image, &image_size);
> > +     status = efi_firmware_verify_image(&image, &image_size, image_index,
> > +                                        &state);
> >       if (status != EFI_SUCCESS)
> > -             return EFI_EXIT(status);
> > +             goto err;
> >
> > -     if (fit_update(image))
> > -             return EFI_EXIT(EFI_DEVICE_ERROR);
> > +     if (fit_update(image)) {
> > +             status = EFI_DEVICE_ERROR;
> > +             goto err;
> > +     }
> >
> > -     return EFI_EXIT(EFI_SUCCESS);
> > +     state.last_attempt_status = LAST_ATTEMPT_STATUS_SUCCESS;
> > +err:
> > +     updated = (status == EFI_SUCCESS) ? true : false;
> > +     efi_firmware_set_fmp_state_var(&state, image_index, updated);
> > +
> > +     return EFI_EXIT(status);
> >  }
> >
> >  const struct efi_firmware_management_protocol efi_fmp_fit = {
> > @@ -391,7 +530,9 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
> >       u16 **abort_reason)
> >  {
> >       int ret;
> > +     bool updated;
> >       efi_status_t status;
> > +     struct fmp_state state = { 0 };
> >
> >       EFI_ENTRY("%p %d %p %zu %p %p %p\n", this, image_index, image,
> >                 image_size, vendor_code, progress, abort_reason);
> > @@ -399,9 +540,10 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
> >       if (!image)
> >               return EFI_EXIT(EFI_INVALID_PARAMETER);
> >
> > -     status = efi_firmware_capsule_authenticate(&image, &image_size);
> > +     status = efi_firmware_verify_image(&image, &image_size, image_index,
> > +                                        &state);
> >       if (status != EFI_SUCCESS)
> > -             return EFI_EXIT(status);
> > +             goto err;
> >
> >       if (IS_ENABLED(CONFIG_FWU_MULTI_BANK_UPDATE)) {
> >               /*
> > @@ -410,16 +552,26 @@ efi_status_t EFIAPI efi_firmware_raw_set_image(
> >                */
> >               ret = fwu_get_image_index(&image_index);
> >               if (ret) {
> > +                     state.last_attempt_status = LAST_ATTEMPT_STATUS_ERROR_UNSUCCESSFUL;
> >                       log_debug("Unable to get FWU image_index\n");
> > -                     return EFI_EXIT(EFI_DEVICE_ERROR);
> > +                     status = EFI_DEVICE_ERROR;
> > +                     goto err;
> >               }
> >       }
> >
> >       if (dfu_write_by_alt(image_index - 1, (void *)image, image_size,
> > -                          NULL, NULL))
> > -             return EFI_EXIT(EFI_DEVICE_ERROR);
> > +                          NULL, NULL)) {
> > +             status = EFI_DEVICE_ERROR;
> > +             state.last_attempt_status = LAST_ATTEMPT_STATUS_ERROR_UNSUCCESSFUL;
> > +             goto err;
> > +     }
> > +
> > +     state.last_attempt_status = LAST_ATTEMPT_STATUS_SUCCESS;
> > +err:
> > +     updated = (status == EFI_SUCCESS) ? true : false;
> > +     efi_firmware_set_fmp_state_var(&state, image_index, updated);
> >
> > -     return EFI_EXIT(EFI_SUCCESS);
> > +     return EFI_EXIT(status);
> >  }
> >
> >  const struct efi_firmware_management_protocol efi_fmp_raw = {
> > --
> > 2.17.1
> >


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