[PATCH v8 3/3] efi_loader: add PE/COFF image measurement
Masahisa Kojima
masahisa.kojima at linaro.org
Tue May 25 15:47:40 CEST 2021
On Tue, 25 May 2021 at 21:57, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> On 14.05.21 02:53, 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.
> >
> > Acked-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > Tested-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> > ---
> >
> > (no changes since v7)
> >
> > Changes in v7:
> > - include hash-checksum.h instead of rsa.h
> > - select HASH_CALCULATE in Kconfig, not to update lib/Makefile
> > - rebased the base code
> >
> > Changes in v6:
> > - update lib/Makefile to add hash-checksum.c as a compilation target
> >
> > (no changes since v2)
> >
> > Changes in v2:
> > - Remove duplicate <efi.h> include
> > - Remove unnecessary __packed attribute
> > - Add all EV_EFI_* event definition
> > - Create common function to prepare 8-byte aligned image
> > - Add measurement for EV_EFI_BOOT_SERVICES_DRIVER and
> > EV_EFI_RUNTIME_SERVICES_DRIVER
> > - Use efi_search_protocol() to get device_path
> > - Add function comment
> >
> > include/efi_loader.h | 6 +
> > include/efi_tcg2.h | 9 ++
> > include/tpm-v2.h | 18 +++
> > lib/efi_loader/Kconfig | 1 +
> > lib/efi_loader/efi_image_loader.c | 59 +++++++--
> > lib/efi_loader/efi_tcg2.c | 207 ++++++++++++++++++++++++++++--
> > 6 files changed, 276 insertions(+), 24 deletions(-)
> >
> > diff --git a/include/efi_loader.h b/include/efi_loader.h
> > index de1a496a97..9f2854a255 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,
> > @@ -847,6 +851,8 @@ bool efi_secure_boot_enabled(void);
> >
> > bool efi_capsule_auth_enabled(void);
> >
> > +void *efi_prepare_aligned_image(void *efi, u64 *efi_size, void **new_efi);
> > +
> > bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp,
> > WIN_CERTIFICATE **auth, size_t *auth_len);
> >
> > diff --git a/include/efi_tcg2.h b/include/efi_tcg2.h
> > index 40e241ce31..bcfb98168a 100644
> > --- a/include/efi_tcg2.h
> > +++ b/include/efi_tcg2.h
> > @@ -9,6 +9,7 @@
> > #if !defined _EFI_TCG2_PROTOCOL_H_
> > #define _EFI_TCG2_PROTOCOL_H_
> >
> > +#include <efi_api.h>
> > #include <tpm-v2.h>
> >
> > #define EFI_TCG2_PROTOCOL_GUID \
> > @@ -53,6 +54,14 @@ 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[];
> > +};
> > +
> > 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 7de7d6a57d..247b386967 100644
> > --- a/include/tpm-v2.h
> > +++ b/include/tpm-v2.h
> > @@ -70,6 +70,24 @@ struct udevice;
> > #define EV_TABLE_OF_DEVICES ((u32)0x0000000B)
> > #define EV_COMPACT_HASH ((u32)0x0000000C)
> >
> > +/*
> > + * event types, cf.
> > + * "TCG PC Client Platform Firmware Profile Specification", Family "2.0"
> > + * rev 1.04, June 3, 2019
> > + */
> > +#define EV_EFI_EVENT_BASE ((u32)0x80000000)
> > +#define EV_EFI_VARIABLE_DRIVER_CONFIG ((u32)0x80000001)
> > +#define EV_EFI_VARIABLE_BOOT ((u32)0x80000002)
> > +#define EV_EFI_BOOT_SERVICES_APPLICATION ((u32)0x80000003)
> > +#define EV_EFI_BOOT_SERVICES_DRIVER ((u32)0x80000004)
> > +#define EV_EFI_RUNTIME_SERVICES_DRIVER ((u32)0x80000005)
> > +#define EV_EFI_GPT_EVENT ((u32)0x80000006)
> > +#define EV_EFI_ACTION ((u32)0x80000007)
> > +#define EV_EFI_PLATFORM_FIRMWARE_BLOB ((u32)0x80000008)
> > +#define EV_EFI_HANDOFF_TABLES ((u32)0x80000009)
> > +#define EV_EFI_HCRTM_EVENT ((u32)0x80000010)
> > +#define EV_EFI_VARIABLE_AUTHORITY ((u32)0x800000E0)
> > +
> > /* TPMS_TAGGED_PROPERTY Structure */
> > struct tpms_tagged_property {
> > u32 property;
> > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > index 98845b8ba3..0e6200fa25 100644
> > --- a/lib/efi_loader/Kconfig
> > +++ b/lib/efi_loader/Kconfig
> > @@ -309,6 +309,7 @@ config EFI_TCG2_PROTOCOL
> > select SHA512_ALGO
> > select SHA384
> > select SHA512
> > + select HASH_CALCULATE
> > help
> > Provide a EFI_TCG2_PROTOCOL implementation using the TPM hardware
> > of the platform.
> > diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
> > index fe1ee198e2..f37a85e56e 100644
> > --- a/lib/efi_loader/efi_image_loader.c
> > +++ b/lib/efi_loader/efi_image_loader.c
> > @@ -302,6 +302,40 @@ static int cmp_pe_section(const void *arg1, const void *arg2)
> > return 1;
> > }
> >
> > +/**
> > + * efi_prepare_aligned_image() - prepare 8-byte aligned image
> > + * @efi: pointer to the EFI binary
> > + * @efi_size: size of @efi binary
> > + * @new_efi: pointer to the newly allocated image
> > + *
> > + * If @efi is not 8-byte aligned, this function newly allocates
> > + * the image buffer and updates @efi_size.
> > + *
> > + * Return: valid pointer to a image, return NULL if allocation fails.
> > + */
> > +void *efi_prepare_aligned_image(void *efi, u64 *efi_size, void **new_efi)
> > +{
> > + size_t new_efi_size;
> > + void *p;
> > +
> > + /*
> > + * 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)) {
>
> Why don't you unconditionally copy to a new buffer? Then the caller can
> free the return value unconditionally.
>
> > + new_efi_size = ALIGN(*efi_size, 8);
> > + p = calloc(new_efi_size, 1);
> > + if (!p)
> > + return NULL;
> > + memcpy(p, efi, *efi_size);
> > + *efi_size = new_efi_size;
> > + *new_efi = p;
> > + return p;
> > + } else {
> > + return efi;
> > + }
> > +}
> > +
> > /**
> > * efi_image_parse() - parse a PE image
> > * @efi: Pointer to image
> > @@ -561,7 +595,7 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
> > struct efi_signature_store *db = NULL, *dbx = NULL;
> > void *new_efi = NULL;
> > u8 *auth, *wincerts_end;
> > - size_t new_efi_size, auth_size;
> > + size_t auth_size;
> > bool ret = false;
> >
> > EFI_PRINT("%s: Enter, %d\n", __func__, ret);
> > @@ -569,19 +603,9 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
> > if (!efi_secure_boot_enabled())
> > return true;
> >
> > - /*
> > - * Size must be 8-byte aligned and the trailing bytes must be
> > - * zero'ed. Otherwise hash value may be incorrect.
> > - */
> > - if (efi_size & 0x7) {
> > - new_efi_size = (efi_size + 0x7) & ~0x7ULL;
> > - new_efi = calloc(new_efi_size, 1);
> > - if (!new_efi)
> > - return false;
> > - memcpy(new_efi, efi, efi_size);
> > - efi = new_efi;
> > - efi_size = new_efi_size;
> > - }
> > + efi = efi_prepare_aligned_image(efi, (u64 *)&efi_size, &new_efi);
> > + if (!efi)
> > + return false;
> >
> > if (!efi_image_parse(efi, efi_size, ®s, &wincerts,
> > &wincerts_len)) {
> > @@ -891,6 +915,13 @@ 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 c8616bf31e..316eaf572b 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/hash-checksum.h>
> > #include <u-boot/sha1.h>
> > #include <u-boot/sha256.h>
> > #include <u-boot/sha512.h>
> > @@ -706,6 +708,183 @@ out:
> > return EFI_EXIT(ret);
> > }
> >
> > +/**
> > + * tcg2_hash_pe_image() - calculate PE/COFF image hash
> > + *
> > + * @efi: pointer to the EFI binary
> > + * @efi_size: size of @efi binary
> > + * @digest_list: list of digest algorithms to extend
> > + *
> > + * Return: status code
> > + */
> > +static efi_status_t tcg2_hash_pe_image(void *efi, u64 efi_size,
> > + struct tpml_digest_values *digest_list)
> > +{
> > + WIN_CERTIFICATE *wincerts = NULL;
> > + size_t wincerts_len;
> > + struct efi_image_regions *regs = NULL;
> > + void *new_efi = NULL;
> > + u8 hash[TPM2_SHA512_DIGEST_SIZE];
> > + efi_status_t ret;
> > + u32 active;
> > + int i;
> > +
> > + efi = efi_prepare_aligned_image(efi, &efi_size, &new_efi);
> > + if (!efi)
> > + return EFI_OUT_OF_RESOURCES;
> > +
> > + 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);
> > + break;
> > + case TPM2_ALG_SHA256:
> > + hash_calculate("sha256", regs->reg, regs->num, hash);
> > + break;
> > + case TPM2_ALG_SHA384:
> > + hash_calculate("sha384", regs->reg, regs->num, hash);
> > + break;
> > + case TPM2_ALG_SHA512:
> > + hash_calculate("sha512", regs->reg, regs->num, hash);
> > + 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));
> > + digest_list->count++;
> > + }
> > +
> > +out:
> > + free(new_efi);
>
> new_efi may be a buffer allocated with calloc() in
> efi_prepare_aligned_image() or it may be a buffer passed by an EFI
> application to LoadImage(). You must not free() memory that was never
> allocated via calloc() or malloc().
new_efi will possibly point two kinds of pointer, calloced buffer in
efi_prepare_aligned_image() or NULL.
Buffer passed by an EFI application to LoadImage() is preserved in
variable "efi"
and will not be freed in my code.
Ilias also pointed that efi_prepare_aligned_image() returns and stores
the same pointer looks a bit weird, current implementation is easy to
get misunderstood.
So I would like to remove **new_efi parameter from efi_prepare_aligned_image(),
code will be something like:
+ new_efi = efi_prepare_aligned_image(efi, (u64 *)&efi_size);
- if (!efi_image_parse(efi, efi_size, ®s, &wincerts,
+ if (!efi_image_parse(new_efi, efi_size, ®s, &wincerts,
<--snip-->
+ if (new_efi != efi)
free(new_efi);
"new_efi" will point newly calloced buffer or Buffer passed by an EFI
application to LoadImage().
"efi" always preserves the buffer passed by an EFI application to LoadImage().
Thanks,
Masahisa Kojima
>
> Best regards
>
> Heinrich
>
> > + free(regs);
> > +
> > + return ret;
> > +}
> > +
> > +/**
> > + * tcg2_measure_pe_image() - measure PE/COFF image
> > + *
> > + * @efi: pointer to the EFI binary
> > + * @efi_size: size of @efi binary
> > + * @handle: loaded image handle
> > + * @loaded_image: loaded image protocol
> > + *
> > + * Return: status code
> > + */
> > +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;
> > + struct efi_device_path *device_path;
> > + u32 device_path_length;
> > + IMAGE_DOS_HEADER *dos;
> > + IMAGE_NT_HEADERS32 *nt;
> > + struct efi_handler *handler;
> > +
> > + ret = platform_get_tpm2_device(&dev);
> > + if (ret != EFI_SUCCESS)
> > + return ret;
> > +
> > + switch (handle->image_type) {
> > + case IMAGE_SUBSYSTEM_EFI_APPLICATION:
> > + pcr_index = 4;
> > + event_type = EV_EFI_BOOT_SERVICES_APPLICATION;
> > + break;
> > + case IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER:
> > + pcr_index = 2;
> > + event_type = EV_EFI_BOOT_SERVICES_DRIVER;
> > + break;
> > + case IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER:
> > + pcr_index = 2;
> > + event_type = EV_EFI_RUNTIME_SERVICES_DRIVER;
> > + break;
> > + default:
> > + 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;
> > +
> > + ret = EFI_CALL(efi_search_protocol(&handle->header,
> > + &efi_guid_loaded_image_device_path,
> > + &handler));
> > + if (ret != EFI_SUCCESS)
> > + return ret;
> > +
> > + device_path = EFI_CALL(handler->protocol_interface);
> > + 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;
> > + image_load_event = (struct uefi_image_load_event *)malloc(event_size);
> > + if (!image_load_event)
> > + return EFI_OUT_OF_RESOURCES;
> > +
> > + 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, (u8 *)image_load_event);
> > +
> > +out:
> > + free(image_load_event);
> > +
> > + return ret;
> > +}
> > +
> > /**
> > * efi_tcg2_hash_log_extend_event() - extend and optionally log events
> > *
> > @@ -758,24 +937,32 @@ 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;
> > - }
> > + IMAGE_NT_HEADERS32 *nt;
> >
> > - pcr_index = efi_tcg_event->header.pcr_index;
> > - event_type = efi_tcg_event->header.event_type;
> > + ret = efi_check_pe((void *)data_to_hash, data_to_hash_len,
> > + (void **)&nt);
> > + if (ret != EFI_SUCCESS) {
> > + log_err("Not a valid PE-COFF file\n");
> > + goto out;
> > + }
> > + ret = tcg2_hash_pe_image((void *)data_to_hash, data_to_hash_len,
> > + &digest_list);
> > + } else {
> > + ret = tcg2_create_digest((u8 *)(uintptr_t)data_to_hash,
> > + data_to_hash_len, &digest_list);
> > + }
> >
> > - ret = tcg2_create_digest((u8 *)(uintptr_t)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_pcr_extend(dev, pcr_index, &digest_list);
> > if (ret != EFI_SUCCESS)
> > goto out;
> >
>
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