diff options
| -rw-r--r-- | cmd/tpm-v2.c | 43 | ||||
| -rw-r--r-- | include/tpm-v2.h | 13 | ||||
| -rw-r--r-- | lib/tpm-v2.c | 42 |
3 files changed, 98 insertions, 0 deletions
diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c index 0a7a5c8074..ea2da97e2a 100644 --- a/cmd/tpm-v2.c +++ b/cmd/tpm-v2.c @@ -106,6 +106,44 @@ static int do_tpm2_pcr_extend(cmd_tbl_t *cmdtp, int flag, int argc, return report_return_code(rc); } +static int do_tpm_pcr_read(cmd_tbl_t *cmdtp, int flag, int argc, + char * const argv[]) +{ + struct udevice *dev; + struct tpm_chip_priv *priv; + u32 index, rc; + unsigned int updates; + void *data; + int ret; + + 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; + + index = simple_strtoul(argv[1], NULL, 0); + if (index >= priv->pcr_count) + return -EINVAL; + + data = map_sysmem(simple_strtoul(argv[2], NULL, 0), 0); + + rc = tpm2_pcr_read(index, priv->pcr_select_min, data, &updates); + if (!rc) { + printf("PCR #%u content (%d known updates):\n", index, updates); + print_byte_string(data, TPM2_DIGEST_LEN); + } + + 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, "", ""), @@ -113,6 +151,7 @@ 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) @@ -148,4 +187,8 @@ 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 25bb15af39..2b8600a185 100644 --- a/include/tpm-v2.h +++ b/include/tpm-v2.h @@ -164,4 +164,17 @@ 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. + * + * @idx Index of the PCR + * @idx_min_sz Minimum size in bytes of the pcrSelect array + * @data Output buffer for contents of the named PCR + * @updates Optional out parameter: number of updates for this PCR + * + * @return code of the operation + */ +u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data, + unsigned int *updates); + #endif /* __TPM_V2_H */ diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c index 476b4ee0d0..7d3834c0e4 100644 --- a/lib/tpm-v2.c +++ b/lib/tpm-v2.c @@ -115,3 +115,45 @@ u32 tpm2_pcr_extend(u32 index, const uint8_t *digest) return tpm_sendrecv_command(command_v2, NULL, NULL); } + +u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data, + unsigned int *updates) +{ + u8 idx_array_sz = max(idx_min_sz, DIV_ROUND_UP(idx, 8)); + u8 command_v2[COMMAND_BUFFER_SIZE] = { + tpm_u16(TPM2_ST_NO_SESSIONS), /* TAG */ + tpm_u32(17 + idx_array_sz), /* 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 */ + idx_array_sz, /* Array size for selection */ + /* bitmap(idx) Selected PCR bitmap */ + }; + size_t response_len = COMMAND_BUFFER_SIZE; + u8 response[COMMAND_BUFFER_SIZE]; + unsigned int pcr_sel_idx = idx / 8; + u8 pcr_sel_bit = BIT(idx % 8); + unsigned int counter = 0; + int ret; + + if (pack_byte_string(command_v2, COMMAND_BUFFER_SIZE, "b", + 17 + pcr_sel_idx, pcr_sel_bit)) + 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; +} |