grub2/grub-read-pcr.patch

166 lines
4.1 KiB
Diff

--- a/include/grub/tpm.h
+++ b/include/grub/tpm.h
@@ -36,6 +36,12 @@
#define EV_IPL 0x0d
+struct grub_tpm_digest {
+ const char * algorithm;
+ unsigned int size;
+ unsigned char value[1]; /* variable length */
+};
+
grub_err_t grub_tpm_measure (unsigned char *buf, grub_size_t size,
grub_uint8_t pcr, const char *description);
int grub_tpm_present (void);
@@ -45,5 +51,7 @@
{
return grub_env_get_bool ("tpm_fail_fatal", false);
}
+struct grub_tpm_digest *grub_tpm_read_pcr (grub_uint8_t index, const char *algo);
+void grub_tpm_digest_free (struct grub_tpm_digest *d);
#endif
--- a/grub-core/commands/efi/tpm.c
+++ b/grub-core/commands/efi/tpm.c
@@ -24,6 +24,7 @@
#include <grub/efi/efi.h>
#include <grub/efi/cc.h>
#include <grub/efi/tpm.h>
+#include <grub/tpm2/tpm2.h>
#include <grub/mm.h>
#include <grub/tpm.h>
#include <grub/term.h>
@@ -186,6 +187,91 @@
return grub_efi_log_event_status (status);
}
+static void
+grub_tpm2_select_pcr(TPML_PCR_SELECTION *o, unsigned int pcrIndex, unsigned int algo)
+{
+ TPMS_PCR_SELECTION *pcr;
+
+ pcr = &o->pcrSelections[o->count++];
+ pcr->hash = algo;
+ pcr->sizeOfSelect = 3;
+ pcr->pcrSelect[TPM2_PCR_TO_SELECT(pcrIndex)] |= TPM2_PCR_TO_BIT(pcrIndex);
+}
+
+struct grub_tpm_hash_info {
+ const char *name;
+ grub_size_t size;
+ int id;
+};
+
+static const struct grub_tpm_hash_info *
+grub_tpm2_get_digest_info (const char *algo)
+{
+ static struct grub_tpm_hash_info __hashes[] = {
+ { "sha256", 32, TPM_ALG_SHA256 }, /* first entry is the default */
+ { "sha512", 64, TPM_ALG_SHA512 },
+ { "sha1", 20, TPM_ALG_SHA1 },
+ { NULL }
+ };
+ struct grub_tpm_hash_info *h;
+
+ if (algo == NULL)
+ return &__hashes[0];
+
+ for (h = __hashes; h->name; ++h)
+ if (!grub_strcmp(h->name, algo))
+ return h;
+
+ return NULL;
+}
+
+static grub_err_t
+grub_tpm2_read_pcr (grub_int8_t pcrIndex, const char *algo, struct grub_tpm_digest **ret)
+{
+ const struct grub_tpm_hash_info *info;
+ TPML_PCR_SELECTION inSelection, outSelection;
+ grub_uint32_t pcrUpdateCounter;
+ TPML_DIGEST digests = { 0 };
+ TPM2B_DIGEST *d;
+ struct grub_tpm_digest *result;
+ int rc;
+
+ info = grub_tpm2_get_digest_info (algo);
+ if (info == NULL)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("Unknown digest algorithm %s"), algo);
+
+ grub_memset(&inSelection, 0, sizeof(inSelection));
+ grub_memset(&outSelection, 0, sizeof(outSelection));
+ grub_tpm2_select_pcr(&inSelection, pcrIndex, info->id);
+
+ rc = TPM2_PCR_Read(
+ NULL,
+ &inSelection,
+ &pcrUpdateCounter,
+ &outSelection,
+ &digests,
+ NULL
+ );
+
+ if (rc != 0)
+ return grub_error (GRUB_ERR_BAD_DEVICE, "TPM2_PCR_Read failed, status=%d", rc);
+
+ d = &digests.digests[0];
+
+ *ret = result = grub_malloc (sizeof (*result) + d->size);
+ grub_memcpy (result->value, d->buffer, d->size);
+ result->algorithm = info->name;
+ result->size = d->size;
+
+ return GRUB_ERR_NONE;
+}
+
+void
+grub_tpm_digest_free (struct grub_tpm_digest *d)
+{
+ grub_free (d);
+}
+
static grub_err_t
grub_tpm2_log_event (grub_efi_handle_t tpm_handle, unsigned char *buf,
grub_size_t size, grub_uint8_t pcr,
@@ -323,3 +409,26 @@
return grub_tpm2_present (tpm);
}
}
+
+struct grub_tpm_digest *
+grub_tpm_read_pcr (grub_uint8_t pcr, const char *algo)
+{
+ grub_efi_handle_t tpm_handle;
+ grub_efi_uint8_t protocol_version;
+ struct grub_tpm_digest *result = NULL;
+
+
+ if (!grub_tpm_handle_find (&tpm_handle, &protocol_version))
+ return 0;
+
+ if (protocol_version != 2)
+ {
+ grub_error (GRUB_ERR_BAD_DEVICE, N_("%s: TPM version %d not implemented"), __func__, protocol_version);
+ return NULL;
+ }
+
+ if (grub_tpm2_read_pcr (pcr, algo, &result))
+ return NULL;
+
+ return result;
+}
--- a/include/grub/tpm2/tpm2.h
+++ b/include/grub/tpm2/tpm2.h
@@ -23,6 +23,10 @@
#include <grub/tpm2/internal/structs.h>
#include <grub/tpm2/internal/functions.h>
+/* Defined in: TCG TPM Specification, v1.59, Part 2, Section 10.6.1. */
+#define TPM2_PCR_TO_SELECT(x) ((x) / 8)
+#define TPM2_PCR_TO_BIT(x) (1 << ((x) % 8))
+
/* Well-Known Windows SRK handle */
#define TPM2_SRK_HANDLE 0x81000001