[U-Boot] [PATCH v4 21/32] tpm: add TPM2_GetCapability command support

Miquel Raynal
2018-05-15T09:57:17Z

Add support for the TPM2_GetCapability command.

Change the command file and the help accordingly.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---
cmd/tpm-v2.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
include/tpm-v2.h | 14 ++++++++++++++
lib/tpm-v2.c | 33 +++++++++++++++++++++++++++++++++
3 files changed, 92 insertions(+)

diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
index 49c22aaeaa..3599763e90 100644
--- a/cmd/tpm-v2.c
+++ b/cmd/tpm-v2.c
@@ -144,6 +144,43 @@ static int do_tpm_pcr_read(cmd_tbl_t *cmdtp, int flag, int argc,
return report_return_code(rc);
}

+static int do_tpm_get_capability(cmd_tbl_t *cmdtp, int flag, int argc,
+ char * const argv[])
+{
+ u32 capability, property, rc;
+ u8 *data;
+ size_t count;
+ int i, j;
+
+ if (argc != 5)
+ return CMD_RET_USAGE;
+
+ capability = simple_strtoul(argv[1], NULL, 0);
+ property = simple_strtoul(argv[2], NULL, 0);
+ data = map_sysmem(simple_strtoul(argv[3], NULL, 0), 0);
+ count = simple_strtoul(argv[4], NULL, 0);
+
+ rc = tpm2_get_capability(capability, property, data, count);
+ if (rc)
+ goto unmap_data;
+
+ printf("Capabilities read from TPM:\n");
+ for (i = 0; i < count; i++) {
+ printf("Property 0x");
+ for (j = 0; j < 4; j++)
+ printf("%02x", data[(i * 8) + j]);
+ printf(": 0x");
+ for (j = 4; j < 8; j++)
+ printf("%02x", data[(i * 8) + j]);
+ printf("\n");
+ }
+
+unmap_data:
+ unmap_sysmem(data);
+
+ return report_return_code(rc);
+}
+
static cmd_tbl_t tpm2_commands[] = {
U_BOOT_CMD_MKENT(info, 0, 1, do_tpm_info, "", ""),
U_BOOT_CMD_MKENT(init, 0, 1, do_tpm_init, "", ""),
@@ -152,6 +189,7 @@ static cmd_tbl_t tpm2_commands[] = {
U_BOOT_CMD_MKENT(clear, 0, 1, do_tpm2_clear, "", ""),
U_BOOT_CMD_MKENT(pcr_extend, 0, 1, do_tpm2_pcr_extend, "", ""),
U_BOOT_CMD_MKENT(pcr_read, 0, 1, do_tpm_pcr_read, "", ""),
+ U_BOOT_CMD_MKENT(get_capability, 0, 1, do_tpm_get_capability, "", ""),
};

cmd_tbl_t *get_tpm_commands(unsigned int *size)
@@ -191,4 +229,11 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a TPMv2.x command",
" Read PCR #<pcr> to memory address <digest_addr>.\n"
" <pcr>: index of the PCR\n"
" <digest_addr>: address to store the a 32-byte SHA256 digest\n"
+"get_capability <capability> <property> <addr> <count>\n"
+" Read and display <count> entries indexed by <capability>/<property>.\n"
+" Values are 4 bytes long and are written at <addr>.\n"
+" <capability>: capability\n"
+" <property>: property\n"
+" <addr>: address to store <count> entries of 4 bytes\n"
+" <count>: number of entries to retrieve\n"
);
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index b9f36b22ba..618026ce2a 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -177,4 +177,18 @@ u32 tpm2_pcr_extend(u32 index, const uint8_t *digest);
u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data,
unsigned int *updates);

+/**
+ * Issue a TPM2_GetCapability command. This implementation is limited
+ * to query property index that is 4-byte wide.
+ *
+ * @capability Partition of capabilities
+ * @property Further definition of capability, limited to be 4 bytes wide
+ * @buf Output buffer for capability information
+ * @prop_count Size of output buffer
+ *
+ * @return code of the operation
+ */
+u32 tpm2_get_capability(u32 capability, u32 property, void *buf,
+ size_t prop_count);
+
#endif /* __TPM_V2_H */
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index a1f1dbc3d6..330844ee31 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -157,3 +157,36 @@ u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data,

return 0;
}
+
+u32 tpm2_get_capability(u32 capability, u32 property, void *buf,
+ size_t prop_count)
+{
+ u8 command_v2[COMMAND_BUFFER_SIZE] = {
+ tpm_u16(TPM2_ST_NO_SESSIONS), /* TAG */
+ tpm_u32(22), /* Length */
+ tpm_u32(TPM2_CC_GET_CAPABILITY), /* Command code */
+
+ tpm_u32(capability), /* Capability */
+ tpm_u32(property), /* Property */
+ tpm_u32(prop_count), /* Property count */
+ };
+ u8 response[COMMAND_BUFFER_SIZE];
+ size_t response_len = COMMAND_BUFFER_SIZE;
+ unsigned int properties_off;
+ int ret;
+
+ ret = tpm_sendrecv_command(command_v2, response, &response_len);
+ if (ret)
+ return ret;
+
+ /*
+ * In the response buffer, the properties are located after the:
+ * tag (u16), response size (u32), response code (u32),
+ * YES/NO flag (u8), TPM_CAP (u32) and TPMU_CAPABILITIES (u32).
+ */
+ properties_off = sizeof(u16) + sizeof(u32) + sizeof(u32) +
+ sizeof(u8) + sizeof(u32) + sizeof(u32);
+ memcpy(buf, &response[properties_off], response_len - properties_off);
+
+ return 0;
+}
--
2.14.1