[PATCH 2/2] efi_loader: add PE/COFF image measurement
Ilias Apalodimas
ilias.apalodimas at linaro.org
Fri Apr 16 22:42:31 CEST 2021
Hi Heinrich,
On Thu, Apr 15, 2021 at 04:08:55PM +0200, Heinrich Schuchardt wrote:
> On 15.04.21 15:30, Masahisa Kojima wrote:
> > "TCG PC Client Platform Firmware Profile Specification"
> > requires to measure every attempt to load and execute
> > a OS Loader(a UEFI application) into PCR[4].
> > This commit adds the PE/COFF image measurement, extends PCR,
> > and appends measurement into Event Log.
> >
> > Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
>
> Please, provide a unit test that we can run in Gitlab CI on either the
> sandbox or QEMU.
The additions to the EFI TCG2 fall under the same category as the initial
patchset and unfortunately suffer from the same problems wrt to using the
sandbox TPM2.
The sandbox capabilities are limited for testing this, starting from the fact
that that we can't even get the tpm2 capabilities we need to start the
protocol correctly.
./drivers/tpm/tpm2_tis_sandbox.c only supports TPM_CAP_TPM_PROPERTIES which is
limited compared to what the TCG code in EFI expects. Similar functionality
is missing from extending and checking PCRs properly etc.
>
> QEMU allows to use a TPM emulation, cf.
> https://qemu-project.gitlab.io/qemu/specs/tpm.html#the-qemu-tpm-emulator-device
> https://github.com/stefanberger/swtpm
Kojima and I will have a look since this is the only viable option in order to
get useful selftests.
Imho we should review and maybe accept this patch in parallel though, since
it's adding more bits of the TCG PC client specification.
Thanks!
/Ilias
>
> Best regards
>
> Heinrich
>
> > ---
> > include/efi_loader.h | 4 +
> > include/efi_tcg2.h | 10 ++
> > include/tpm-v2.h | 1 +
> > lib/efi_loader/efi_image_loader.c | 7 ++
> > lib/efi_loader/efi_tcg2.c | 187 ++++++++++++++++++++++++++++--
> > 5 files changed, 199 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/efi_loader.h b/include/efi_loader.h
> > index de1a496a97..b02bc93c8e 100644
> > --- a/include/efi_loader.h
> > +++ b/include/efi_loader.h
> > @@ -426,6 +426,10 @@ efi_status_t efi_disk_register(void);
> > efi_status_t efi_rng_register(void);
> > /* Called by efi_init_obj_list() to install EFI_TCG2_PROTOCOL */
> > efi_status_t efi_tcg2_register(void);
> > +/* measure the pe-coff image, extend PCR and add Event Log */
> > +efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
> > + struct efi_loaded_image_obj *handle,
> > + struct efi_loaded_image *loaded_image_info);
> > /* Create handles and protocols for the partitions of a block device */
> > int efi_disk_create_partitions(efi_handle_t parent, struct blk_desc *desc,
> > const char *if_typename, int diskid,
> > diff --git a/include/efi_tcg2.h b/include/efi_tcg2.h
> > index 40e241ce31..f8d46c5fd2 100644
> > --- a/include/efi_tcg2.h
> > +++ b/include/efi_tcg2.h
> > @@ -9,6 +9,8 @@
> > #if !defined _EFI_TCG2_PROTOCOL_H_
> > #define _EFI_TCG2_PROTOCOL_H_
> >
> > +#include <efi.h>
> > +#include <efi_api.h>
> > #include <tpm-v2.h>
> >
> > #define EFI_TCG2_PROTOCOL_GUID \
> > @@ -53,6 +55,14 @@ struct efi_tcg2_event {
> > u8 event[];
> > } __packed;
> >
> > +struct uefi_image_load_event {
> > + efi_physical_addr_t image_location_in_memory;
> > + u64 image_length_in_memory;
> > + u64 image_link_time_address;
> > + u64 length_of_device_path;
> > + struct efi_device_path device_path[];
> > +} __packed;
> > +
> > struct efi_tcg2_boot_service_capability {
> > u8 size;
> > struct efi_tcg2_version structure_version;
> > diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> > index df67a196cf..ab9c04dc0a 100644
> > --- a/include/tpm-v2.h
> > +++ b/include/tpm-v2.h
> > @@ -61,6 +61,7 @@ struct udevice;
> > #define EV_S_CRTM_VERSION ((u32)0x00000008)
> > #define EV_CPU_MICROCODE ((u32)0x00000009)
> > #define EV_TABLE_OF_DEVICES ((u32)0x0000000B)
> > +#define EV_EFI_BOOT_SERVICES_APPLICATION ((u32)0x80000003)
> >
> > /* TPMS_TAGGED_PROPERTY Structure */
> > struct tpms_tagged_property {
> > diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
> > index 2c35cb5651..b032ec5dd8 100644
> > --- a/lib/efi_loader/efi_image_loader.c
> > +++ b/lib/efi_loader/efi_image_loader.c
> > @@ -829,6 +829,13 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
> > goto err;
> > }
> >
> > +#if CONFIG_IS_ENABLED(EFI_TCG2_PROTOCOL)
> > + /* Measure an PE/COFF image */
> > + if (tcg2_measure_pe_image(efi, efi_size, handle,
> > + loaded_image_info))
> > + log_err("PE image measurement failed\n");
> > +#endif
> > +
> > /* Copy PE headers */
> > memcpy(efi_reloc, efi,
> > sizeof(*dos)
> > diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> > index ed86a220fb..9fab07605f 100644
> > --- a/lib/efi_loader/efi_tcg2.c
> > +++ b/lib/efi_loader/efi_tcg2.c
> > @@ -13,8 +13,10 @@
> > #include <efi_loader.h>
> > #include <efi_tcg2.h>
> > #include <log.h>
> > +#include <malloc.h>
> > #include <version.h>
> > #include <tpm-v2.h>
> > +#include <u-boot/rsa.h>
> > #include <u-boot/sha1.h>
> > #include <u-boot/sha256.h>
> > #include <u-boot/sha512.h>
> > @@ -709,6 +711,172 @@ out:
> > return EFI_EXIT(ret);
> > }
> >
> > +static efi_status_t tcg2_hash_pe_image(void *efi, u64 efi_size,
> > + struct tpml_digest_values *digest_list)
> > +{
> > + IMAGE_NT_HEADERS32 *nt;
> > + WIN_CERTIFICATE *wincerts = NULL;
> > + size_t wincerts_len;
> > + struct efi_image_regions *regs = NULL;
> > + void *new_efi = NULL;
> > + size_t new_efi_size;
> > + u8 hash[TPM2_SHA512_DIGEST_SIZE];
> > + efi_status_t ret;
> > + u32 active;
> > + int i;
> > +
> > + ret = efi_check_pe(efi, efi_size, (void **)&nt);
> > + if (ret != EFI_SUCCESS) {
> > + log_err("Not a valid PE-COFF file\n");
> > + return EFI_INVALID_PARAMETER;
> > + }
> > +
> > + /*
> > + * Size must be 8-byte aligned and the trailing bytes must be
> > + * zero'ed. Otherwise hash value may be incorrect.
> > + */
> > + if (!IS_ALIGNED(efi_size, 8)) {
> > + new_efi_size = ALIGN(efi_size, 8);
> > + new_efi = calloc(new_efi_size, 1);
> > + if (!new_efi)
> > + return EFI_OUT_OF_RESOURCES;
> > + memcpy(new_efi, efi, efi_size);
> > + efi = new_efi;
> > + efi_size = new_efi_size;
> > + }
> > +
> > + if (!efi_image_parse(efi, efi_size, ®s, &wincerts,
> > + &wincerts_len)) {
> > + log_err("Parsing PE executable image failed\n");
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + ret = __get_active_pcr_banks(&active);
> > + if (ret != EFI_SUCCESS) {
> > + ret = EFI_DEVICE_ERROR;
> > + goto out;
> > + }
> > +
> > + digest_list->count = 0;
> > + for (i = 0; i < MAX_HASH_COUNT; i++) {
> > + u16 hash_alg = hash_algo_list[i].hash_alg;
> > +
> > + if (!(active & alg_to_mask(hash_alg)))
> > + continue;
> > + switch (hash_alg) {
> > + case TPM2_ALG_SHA1:
> > + hash_calculate("sha1", regs->reg, regs->num, hash);
> > + digest_list->count++;
> > + break;
> > + case TPM2_ALG_SHA256:
> > + hash_calculate("sha256", regs->reg, regs->num, hash);
> > + digest_list->count++;
> > + break;
> > + case TPM2_ALG_SHA384:
> > + hash_calculate("sha384", regs->reg, regs->num, hash);
> > + digest_list->count++;
> > + break;
> > + case TPM2_ALG_SHA512:
> > + hash_calculate("sha512", regs->reg, regs->num, hash);
> > + digest_list->count++;
> > + break;
> > + default:
> > + EFI_PRINT("Unsupported algorithm %x\n", hash_alg);
> > + return EFI_INVALID_PARAMETER;
> > + }
> > + digest_list->digests[i].hash_alg = hash_alg;
> > + memcpy(&digest_list->digests[i].digest, hash, (u32)alg_to_len(hash_alg));
> > + }
> > +
> > +out:
> > + free(new_efi);
> > + free(regs);
> > +
> > + return ret;
> > +}
> > +
> > +efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
> > + struct efi_loaded_image_obj *handle,
> > + struct efi_loaded_image *loaded_image)
> > +{
> > + struct tpml_digest_values digest_list;
> > + efi_status_t ret;
> > + struct udevice *dev;
> > + u32 pcr_index, event_type, event_size;
> > + struct uefi_image_load_event *image_load_event;
> > + u8 *event;
> > + struct efi_device_path *device_path;
> > + u32 device_path_length;
> > + IMAGE_DOS_HEADER *dos;
> > + IMAGE_NT_HEADERS32 *nt;
> > +
> > + ret = platform_get_tpm2_device(&dev);
> > + if (ret != EFI_SUCCESS)
> > + return ret;
> > +
> > + if (handle->image_type == IMAGE_SUBSYSTEM_EFI_APPLICATION) {
> > + pcr_index = 4;
> > + event_type = EV_EFI_BOOT_SERVICES_APPLICATION;
> > + } else {
> > + return EFI_UNSUPPORTED;
> > + }
> > +
> > + ret = tcg2_hash_pe_image(efi, efi_size, &digest_list);
> > + if (ret != EFI_SUCCESS)
> > + return ret;
> > +
> > + ret = tcg2_pcr_extend(dev, pcr_index, &digest_list);
> > + if (ret != EFI_SUCCESS)
> > + return ret;
> > +
> > + loaded_image->system_table->boottime->handle_protocol(&handle->header,
> > + &efi_guid_loaded_image_device_path,
> > + (void **)&device_path);
> > + device_path_length = efi_dp_size(device_path);
> > + if (device_path_length > 0) {
> > + /* add end node size */
> > + device_path_length += sizeof(struct efi_device_path);
> > + }
> > + event_size = sizeof(struct uefi_image_load_event) + device_path_length;
> > + event = malloc(event_size);
> > + if (!event)
> > + return EFI_OUT_OF_RESOURCES;
> > +
> > + image_load_event = (struct uefi_image_load_event *)event;
> > + image_load_event->image_location_in_memory = (efi_physical_addr_t)efi;
> > + image_load_event->image_length_in_memory = efi_size;
> > + image_load_event->length_of_device_path = device_path_length;
> > +
> > + dos = (IMAGE_DOS_HEADER *)efi;
> > + nt = (IMAGE_NT_HEADERS32 *)(efi + dos->e_lfanew);
> > + if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
> > + IMAGE_NT_HEADERS64 *nt64 = (IMAGE_NT_HEADERS64 *)nt;
> > +
> > + image_load_event->image_link_time_address =
> > + nt64->OptionalHeader.ImageBase;
> > + } else if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
> > + image_load_event->image_link_time_address =
> > + nt->OptionalHeader.ImageBase;
> > + } else {
> > + ret = EFI_INVALID_PARAMETER;
> > + goto out;
> > + }
> > +
> > + if (device_path_length > 0) {
> > + memcpy(image_load_event->device_path, device_path,
> > + device_path_length);
> > + }
> > +
> > + ret = tcg2_agile_log_append(pcr_index, event_type, &digest_list,
> > + event_size, event);
> > +
> > +out:
> > + free(event);
> > +
> > + return ret;
> > +}
> > +
> > /**
> > * efi_tcg2_hash_log_extend_event() - extend and optionally log events
> > *
> > @@ -761,24 +929,23 @@ efi_tcg2_hash_log_extend_event(struct efi_tcg2_protocol *this, u64 flags,
> > /*
> > * if PE_COFF_IMAGE is set we need to make sure the image is not
> > * corrupted, verify it and hash the PE/COFF image in accordance with
> > - * the procedure specified in "Calculating the PE Image Hash"
> > - * section of the "Windows Authenticode Portable Executable Signature
> > + * the procedure specified in "Calculating the PE Image Hash"
> > + * section of the "Windows Authenticode Portable Executable Signature
> > * Format"
> > - * Not supported for now
> > */
> > if (flags & PE_COFF_IMAGE) {
> > - ret = EFI_UNSUPPORTED;
> > - goto out;
> > + ret = tcg2_hash_pe_image((void *)data_to_hash, data_to_hash_len,
> > + &digest_list);
> > + } else {
> > + ret = tcg2_create_digest((u8 *)data_to_hash, data_to_hash_len,
> > + &digest_list);
> > }
> > + if (ret != EFI_SUCCESS)
> > + goto out;
> >
> > pcr_index = efi_tcg_event->header.pcr_index;
> > event_type = efi_tcg_event->header.event_type;
> >
> > - ret = tcg2_create_digest((u8 *)data_to_hash, data_to_hash_len,
> > - &digest_list);
> > - if (ret != EFI_SUCCESS)
> > - goto out;
> > -
> > ret = tcg2_pcr_extend(dev, pcr_index, &digest_list);
> > if (ret != EFI_SUCCESS)
> > goto out;
> >
>
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