tpm: implement TPM 2.0 capability to get active PCR banks

This patch implements the TPM 2.0 capability TPM_CAP_PCRS to
retrieve the active PCR banks from the TPM. This is needed
to enable extending all active banks as recommended by TPM 2.0
TCG Specification.

Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Kenneth Goldman <kgold@linux.vnet.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index dbe0c5a72c67dddb24b05b6895f5ff2908c56f0e..db0398a4e3e5283d09bf6b16cce4f7f646058e91 100644 (file)
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -97,6 +97,7 @@ enum tpm2_return_codes {
 };
 
 enum tpm2_algorithms {
+       TPM2_ALG_ERROR          = 0x0000,
        TPM2_ALG_SHA1           = 0x0004,
        TPM2_ALG_KEYEDHASH      = 0x0008,
        TPM2_ALG_SHA256         = 0x000B,
@@ -127,6 +128,7 @@ enum tpm2_permanent_handles {
 };
 
 enum tpm2_capabilities {
+       TPM2_CAP_PCRS           = 5,
        TPM2_CAP_TPM_PROPERTIES = 6,
 };
 
@@ -187,6 +189,8 @@ struct tpm_chip {
 
        const struct attribute_group *groups[3];
        unsigned int groups_cnt;
+
+       u16 active_banks[7];
 #ifdef CONFIG_ACPI
        acpi_handle acpi_dev_handle;
        char ppi_version[TPM_PPI_VERSION_LEN + 1];
@@ -540,4 +544,5 @@ int tpm2_auto_startup(struct tpm_chip *chip);
 void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type);
 unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
 int tpm2_probe(struct tpm_chip *chip);
+ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip);
 #endif

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 42fe3dde0d8cf9c1345474595a8ac3dd459718db..6fbd42c2a5284b45c17a99d4b3406377b910570d 100644 (file)
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -1030,3 +1030,80 @@ out:
                rc = -ENODEV;
        return rc;
 }
+
+struct tpm2_pcr_selection {
+       __be16  hash_alg;
+       u8  size_of_select;
+       u8  pcr_select[3];
+} __packed;
+
+/**
+ * tpm2_get_pcr_allocation() - get TPM active PCR banks.
+ *
+ * @chip: TPM chip to use.
+ *
+ * Return: Same as with tpm_transmit_cmd.
+ */
+ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
+{
+       struct tpm2_pcr_selection pcr_selection;
+       struct tpm_buf buf;
+       void *marker;
+       void *end;
+       void *pcr_select_offset;
+       unsigned int count;
+       u32 sizeof_pcr_selection;
+       u32 rsp_len;
+       int rc;
+       int i = 0;
+
+       rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+       if (rc)
+               return rc;
+
+       tpm_buf_append_u32(&buf, TPM2_CAP_PCRS);
+       tpm_buf_append_u32(&buf, 0);
+       tpm_buf_append_u32(&buf, 1);
+
+       rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, 9, 0,
+                             "get tpm pcr allocation");
+       if (rc)
+               goto out;
+
+       count = be32_to_cpup(
+               (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
+
+       if (count > ARRAY_SIZE(chip->active_banks)) {
+               rc = -ENODEV;
+               goto out;
+       }
+
+       marker = &buf.data[TPM_HEADER_SIZE + 9];
+
+       rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
+       end = &buf.data[rsp_len];
+
+       for (i = 0; i < count; i++) {
+               pcr_select_offset = marker +
+                       offsetof(struct tpm2_pcr_selection, size_of_select);
+               if (pcr_select_offset >= end) {
+                       rc = -EFAULT;
+                       break;
+               }
+
+               memcpy(&pcr_selection, marker, sizeof(pcr_selection));
+               chip->active_banks[i] = be16_to_cpu(pcr_selection.hash_alg);
+               sizeof_pcr_selection = sizeof(pcr_selection.hash_alg) +
+                       sizeof(pcr_selection.size_of_select) +
+                       pcr_selection.size_of_select;
+               marker = marker + sizeof_pcr_selection;
+       }
+
+out:
+       if (i < ARRAY_SIZE(chip->active_banks))
+               chip->active_banks[i] = TPM2_ALG_ERROR;
+
+       tpm_buf_destroy(&buf);
+
+       return rc;
+}