[U-Boot] [PATCH v4 19/32] tpm: add TPM2_PCR_Extend command support

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

Add support for the TPM2_PCR_Extend 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 | 37 +++++++++++++++++++++++++++++++++++++
include/tpm-v2.h | 10 ++++++++++
lib/tpm-v2.c | 38 ++++++++++++++++++++++++++++++++++++++
3 files changed, 85 insertions(+)

diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
index 9f6a8fc0b6..df6cd6919c 100644
--- a/cmd/tpm-v2.c
+++ b/cmd/tpm-v2.c
@@ -7,6 +7,7 @@
#include <common.h>
#include <dm.h>
#include <log.h>
+#include <mapmem.h>
#include <tpm-common.h>
#include <tpm-v2.h>
#include "tpm-user-utils.h"
@@ -74,12 +75,44 @@ static int do_tpm2_clear(cmd_tbl_t *cmdtp, int flag, int argc,
return report_return_code(tpm2_clear(handle, pw, pw_sz));
}

+static int do_tpm2_pcr_extend(cmd_tbl_t *cmdtp, int flag, int argc,
+ char * const argv[])
+{
+ struct udevice *dev;
+ struct tpm_chip_priv *priv;
+ u32 index = simple_strtoul(argv[1], NULL, 0);
+ void *digest = map_sysmem(simple_strtoul(argv[2], NULL, 0), 0);
+ int ret;
+ u32 rc;
+
+ if (argc != 3)
+ return CMD_RET_USAGE;
+
+ ret = uclass_first_device_err(UCLASS_TPM, &dev);
+ if (ret)
+ return ret;
+
+ priv = dev_get_uclass_priv(dev);
+ if (!priv)
+ return -EINVAL;
+
+ if (index >= priv->pcr_count)
+ return -EINVAL;
+
+ rc = tpm2_pcr_extend(index, digest);
+
+ unmap_sysmem(digest);
+
+ 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, "", ""),
U_BOOT_CMD_MKENT(startup, 0, 1, do_tpm2_startup, "", ""),
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, "", ""),
};

cmd_tbl_t *get_tpm_commands(unsigned int *size)
@@ -111,4 +144,8 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a TPMv2.x command",
" <hierarchy> is one of:\n"
" * TPM2_RH_LOCKOUT\n"
" * TPM2_RH_PLATFORM\n"
+"pcr_extend <pcr> <digest_addr>\n"
+" 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"
);
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index 0d02e4a89b..0706a925ce 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -154,4 +154,14 @@ u32 tpm2_self_test(enum tpm2_yes_no full_test);
*/
u32 tpm2_clear(u32 handle, const char *pw, const ssize_t pw_sz);

+/**
+ * Issue a TPM2_PCR_Extend command.
+ *
+ * @index Index of the PCR
+ * @digest Value representing the event to be recorded
+ *
+ * @return code of the operation
+ */
+u32 tpm2_pcr_extend(u32 index, const uint8_t *digest);
+
#endif /* __TPM_V2_H */
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index e3bfec5082..2696f8145d 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -77,3 +77,41 @@ u32 tpm2_clear(u32 handle, const char *pw, const ssize_t pw_sz)

return tpm_sendrecv_command(command_v2, NULL, NULL);
}
+
+u32 tpm2_pcr_extend(u32 index, const uint8_t *digest)
+{
+ u8 command_v2[COMMAND_BUFFER_SIZE] = {
+ tpm_u16(TPM2_ST_SESSIONS), /* TAG */
+ tpm_u32(33 + TPM2_DIGEST_LEN), /* Length */
+ tpm_u32(TPM2_CC_PCR_EXTEND), /* Command code */
+
+ /* HANDLE */
+ tpm_u32(index), /* Handle (PCR Index) */
+
+ /* AUTH_SESSION */
+ tpm_u32(9), /* Authorization size */
+ tpm_u32(TPM2_RS_PW), /* Session handle */
+ tpm_u16(0), /* Size of <nonce> */
+ /* <nonce> (if any) */
+ 0, /* Attributes: Cont/Excl/Rst */
+ tpm_u16(0), /* Size of <hmac/password> */
+ /* <hmac/password> (if any) */
+ tpm_u32(1), /* Count (number of hashes) */
+ tpm_u16(TPM2_ALG_SHA256), /* Algorithm of the hash */
+ /* STRING(digest) Digest */
+ };
+ unsigned int offset = 33;
+ int ret;
+
+ /*
+ * Fill the command structure starting from the first buffer:
+ * - the digest
+ */
+ ret = pack_byte_string(command_v2, sizeof(command_v2), "s",
+ offset, digest, TPM2_DIGEST_LEN);
+ offset += TPM2_DIGEST_LEN;
+ if (ret)
+ return TPM_LIB_ERROR;
+
+ return tpm_sendrecv_command(command_v2, NULL, NULL);
+}
--
2.14.1