Add support for the TPM2_PCR_Read command.
Change the command file and the help accordingly.
Signed-off-by: Miquel Raynal <miquel.ray...@bootlin.com>
---
cmd/tpm-v2.c | 27 +++++++++++++++++++++++++++
include/tpm-v2.h | 11 +++++++++++
lib/tpm-v2.c | 43 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+)
diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
index 6e19adbfe6..a61d751b4a 100644
--- a/cmd/tpm-v2.c
+++ b/cmd/tpm-v2.c
@@ -86,6 +86,28 @@ static int do_tpm2_pcr_extend(cmd_tbl_t *cmdtp, int flag,
int argc,
return report_return_code(tpm2_pcr_extend(index, digest));
}
+static int do_tpm_pcr_read(cmd_tbl_t *cmdtp, int flag, int argc,
+ char * const argv[])
+{
+ u32 index, rc;
+ unsigned int updates;
+ void *data;
+
+ if (argc != 3)
+ return CMD_RET_USAGE;
+
+ index = simple_strtoul(argv[1], NULL, 0);
+ data = (void *)simple_strtoul(argv[2], NULL, 0);
+
+ rc = tpm2_pcr_read(index, data, &updates);
+ if (!rc) {
+ printf("PCR #%u content (%d known updates):\n", index, updates);
+ print_byte_string(data, TPM2_DIGEST_LEN);
+ }
+
+ 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, "", ""),
@@ -93,6 +115,7 @@ static cmd_tbl_t tpm2_commands[] = {
U_BOOT_CMD_MKENT(self_test, 0, 1, do_tpm2_self_test, "", ""),
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, "", ""),
};
cmd_tbl_t *get_tpm_commands(unsigned int *size)
@@ -128,4 +151,8 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a
TPMv2.x command",
" Extend PCR #<pcr> with digest at <digest_addr>.\n"
" <pcr>: index of the PCR\n"
" <digest_addr>: address of a 32-byte SHA256 digest\n"
+"pcr_read <pcr> <digest_addr>\n"
+" 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"
);
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index 94c1df77b7..54d14df365 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -164,4 +164,15 @@ u32 tpm2_clear(u32 handle, const char *pw, const ssize_t
pw_sz);
*/
u32 tpm2_pcr_extend(u32 index, const uint8_t *digest);
+/**
+ * Issue a TPM2_PCR_Read command.
+ *
+ * @param index Index of the PCR
+ * @param data Output buffer for contents of the named PCR
+ * @param updates Optional out parameter: number of updates for this PCR
+ *
+ * @return return code of the operation
+ */
+u32 tpm2_pcr_read(u32 index, void *data, unsigned int *updates);
+
#endif /* __TPM_V2_H */
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 2696f8145d..d557b08f8b 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -115,3 +115,46 @@ u32 tpm2_pcr_extend(u32 index, const uint8_t *digest)
return tpm_sendrecv_command(command_v2, NULL, NULL);
}
+
+u32 tpm2_pcr_read(u32 index, void *data, unsigned int *updates)
+{
+ u8 command_v2[COMMAND_BUFFER_SIZE] = {
+ tpm_u16(TPM2_ST_NO_SESSIONS), /* TAG */
+ tpm_u32(20), /* Length */
+ tpm_u32(TPM2_CC_PCR_READ), /* Command code */
+
+ /* TPML_PCR_SELECTION */
+ tpm_u32(1), /* Number of selections */
+ tpm_u16(TPM2_ALG_SHA256), /* Algorithm of the hash */
+ 3, /* Array size for selection */
+ /* bitmap(index) Selected PCR bitmap */
+ };
+ size_t response_len = COMMAND_BUFFER_SIZE;
+ u8 response[COMMAND_BUFFER_SIZE];
+ unsigned int counter = 0;
+ u8 pcr_sel[3] = {};
+ int ret;
+
+ if (index >= 24)
+ return TPM_LIB_ERROR;
+
+ pcr_sel[index / 8] = BIT(index % 8);
+ if (pack_byte_string(command_v2, COMMAND_BUFFER_SIZE, "bbb",
+ 17, pcr_sel[0], 18, pcr_sel[1], 19, pcr_sel[2]))
+ return TPM_LIB_ERROR;
+
+ ret = tpm_sendrecv_command(command_v2, response, &response_len);
+ if (ret)
+ return ret;
+
+ if (unpack_byte_string(response, response_len, "ds",
+ 10, &counter,
+ response_len - TPM2_DIGEST_LEN, data,
+ TPM2_DIGEST_LEN))
+ return TPM_LIB_ERROR;
+
+ if (updates)
+ *updates = counter;
+
+ return 0;
+}
--
2.14.1
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