On Fri, 17 Jan 2025 at 18:40, Raymond Mao <raymond....@linaro.org> wrote:
>
> TPM2_PCR_Allocate command is required to reconfigure a TPM device
> to enable or disable algorithms in run-time, thus this patch introduces
> the implementation of PCR allocate APIs and adds related cmd functions
> for testing.
>
> To test the feature, ensure that TPM is started up.
> Run pcr_allocate command to turn on/off an algorithm, multiple calls
> are supported and all changes will be cached:
> `tpm2 pcr_allocate <algorithm_name> <on|off>`
> Run startup command with argument 'off' to shutdown the TPM.
> `tpm2 startup TPM2_SU_CLEAR off`
> Reboot the board via `reset` to activate the changes.
>
> Signed-off-by: Raymond Mao <raymond....@linaro.org>
> ---
> changes in v2
> - Fixed typos.
> - Print the algorithm name directly.
> - Check if the algorithm supported by the TPM device before allocate.
>
> cmd/tpm-v2.c | 114 +++++++++++++++++++++++++++++++++++++++++++
> include/tpm-v2.h | 29 +++++++++++
> lib/tpm-v2.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 267 insertions(+)
>
> diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
> index a6d57ee7c4..a62862e94f 100644
> --- a/cmd/tpm-v2.c
> +++ b/cmd/tpm-v2.c
> @@ -232,6 +232,106 @@ unmap_data:
> return report_return_code(rc);
> }
>
> +static u32 select_mask(u32 mask, enum tpm2_algorithms algo, bool select)
> +{
> + size_t i;
> +
> + for (i = 0; i < ARRAY_SIZE(hash_algo_list); i++) {
> + if (hash_algo_list[i].hash_alg != algo)
> + continue;
> +
> + if (select)
> + mask |= hash_algo_list[i].hash_mask;
> + else
> + mask &= ~hash_algo_list[i].hash_mask;
> +
> + break;
> + }
> +
> + return mask;
> +}
> +
> +static bool
> +is_algo_in_pcrs(enum tpm2_algorithms algo, struct tpml_pcr_selection *pcrs)
> +{
> + size_t i;
> +
> + for (i = 0; i < pcrs->count; i++) {
> + if (algo == pcrs->selection[i].hash)
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static int do_tpm2_pcrallocate(struct cmd_tbl *cmdtp, int flag, int argc,
> + char *const argv[])
> +{
> + struct udevice *dev;
> + int ret;
> + enum tpm2_algorithms algo;
> + const char *pw = (argc < 4) ? NULL : argv[3];
> + const ssize_t pw_sz = pw ? strlen(pw) : 0;
> + static struct tpml_pcr_selection pcr = { 0 };
> + u32 pcr_len = 0;
> + bool bon = false;
> + static u32 mask;
> + int i;
> +
> + /* argv[1]: algorithm (bank), argv[2]: on/off */
> + if (argc < 3 || argc > 4)
> + return CMD_RET_USAGE;
> +
> + if (!strcasecmp("on", argv[2]))
> + bon = true;
> + else if (strcasecmp("off", argv[2]))
> + return CMD_RET_USAGE;
> +
> + algo = tpm2_name_to_algorithm(argv[1]);
> + if (algo == -EINVAL)
> + return CMD_RET_USAGE;
> +
> + ret = get_tpm(&dev);
> + if (ret)
> + return ret;
> +
> + if (!pcr.count) {
> + /*
> + * Get current active algorithms (banks), PCRs and mask via
> the
> + * first call
> + */
> + ret = tpm2_get_pcr_info(dev, &pcr);
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < pcr.count; i++) {
> + struct tpms_pcr_selection *sel = &pcr.selection[i];
> + const char *name;
> +
> + if (!tpm2_is_active_bank(sel))
> + continue;
> +
> + mask = select_mask(mask, sel->hash, true);
> + name = tpm2_algorithm_name(sel->hash);
> + if (name)
> + printf("Active bank[%d]: %s\n", i, name);
> + }
> + }
> +
> + if (!is_algo_in_pcrs(algo, &pcr)) {
> + printf("%s is not supported by the tpm device\n", argv[1]);
> + return CMD_RET_USAGE;
> + }
> +
> + mask = select_mask(mask, algo, bon);
> + ret = tpm2_pcr_config_algo(dev, mask, &pcr, &pcr_len);
> + if (ret)
> + return ret;
> +
> + return report_return_code(tpm2_send_pcr_allocate(dev, pw, pw_sz, &pcr,
> + pcr_len));
> +}
> +
> static int do_tpm_dam_reset(struct cmd_tbl *cmdtp, int flag, int argc,
> char *const argv[])
> {
> @@ -401,6 +501,7 @@ static struct cmd_tbl tpm2_commands[] = {
> do_tpm_pcr_setauthpolicy, "", ""),
> U_BOOT_CMD_MKENT(pcr_setauthvalue, 0, 1,
> do_tpm_pcr_setauthvalue, "", ""),
> + U_BOOT_CMD_MKENT(pcr_allocate, 0, 1, do_tpm2_pcrallocate, "", ""),
> };
>
> struct cmd_tbl *get_tpm2_commands(unsigned int *size)
> @@ -481,4 +582,17 @@ U_BOOT_CMD(tpm2, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a
> TPMv2.x command",
> " <pcr>: index of the PCR\n"
> " <key>: secret to protect the access of PCR #<pcr>\n"
> " <password>: optional password of the PLATFORM hierarchy\n"
> +"pcr_allocate <algorithm> <on/off> [<password>]\n"
> +" Issue a TPM2_PCR_Allocate Command to reconfig PCR bank algorithm.\n"
> +" <algorithm> is one of:\n"
> +" * sha1\n"
> +" * sha256\n"
> +" * sha384\n"
> +" * sha512\n"
> +" <on|off> is one of:\n"
> +" * on - Select all available PCRs associated with the specified\n"
> +" algorithm (bank)\n"
> +" * off - Clear all available PCRs associated with the specified\n"
> +" algorithm (bank)\n"
> +" <password>: optional password\n"
> );
> diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> index f66a8e1bf4..af3158f6e4 100644
> --- a/include/tpm-v2.h
> +++ b/include/tpm-v2.h
> @@ -230,6 +230,7 @@ enum tpm2_command_codes {
> TPM2_CC_PCR_READ = 0x017E,
> TPM2_CC_PCR_EXTEND = 0x0182,
> TPM2_CC_PCR_SETAUTHVAL = 0x0183,
> + TPM2_CC_PCR_ALLOCATE = 0x012B,
> TPM2_CC_SHUTDOWN = 0x0145,
> };
>
> @@ -702,6 +703,34 @@ u32 tpm2_report_state(struct udevice *dev, uint
> vendor_cmd, uint vendor_subcmd,
> u32 tpm2_enable_nvcommits(struct udevice *dev, uint vendor_cmd,
> uint vendor_subcmd);
>
> +/**
> + * tpm2_pcr_config_algo() - Allocate the active PCRs. Requires reboot
> + *
> + * @dev TPM device
> + * @algo_mask Mask of the algorithms
> + * @pcr PCR structure for allocation
> + * @pcr_len Actual PCR data length
> + *
> + * Return: code of the operation
> + */
> +u32 tpm2_pcr_config_algo(struct udevice *dev, u32 algo_mask,
> + struct tpml_pcr_selection *pcr, u32 *pcr_len);
> +
> +/**
> + * tpm2_send_pcr_allocate() - Send PCR allocate command. Requires reboot
> + *
> + * @dev TPM device
> + * @pw Platform password
> + * @pw_sz Length of the password
> + * @pcr PCR structure for allocation
> + * @pcr_len Actual PCR data length
> + *
> + * Return: code of the operation
> + */
> +u32 tpm2_send_pcr_allocate(struct udevice *dev, const char *pw,
> + const ssize_t pw_sz, struct tpml_pcr_selection
> *pcr,
> + u32 pcr_len);
> +
> /**
> * tpm2_auto_start() - start up the TPM and perform selftests.
> * If a testable function has not been tested and is
> diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> index 3946ac2dbb..045b5dd9eb 100644
> --- a/lib/tpm-v2.c
> +++ b/lib/tpm-v2.c
> @@ -400,6 +400,130 @@ u32 tpm2_get_capability(struct udevice *dev, u32
> capability, u32 property,
> return 0;
> }
>
> +u32 tpm2_pcr_config_algo(struct udevice *dev, u32 algo_mask,
> + struct tpml_pcr_selection *pcr, u32 *pcr_len)
> +{
> + int i;
> +
> + if (pcr->count > TPM2_NUM_PCR_BANKS)
> + return TPM_LIB_ERROR;
> +
> + *pcr_len = sizeof(pcr->count);
> +
> + for (i = 0; i < pcr->count; i++) {
> + struct tpms_pcr_selection *sel = &pcr->selection[i];
> + u8 pad = 0;
> + int j;
> +
> + if (sel->size_of_select > TPM2_PCR_SELECT_MAX)
> + return TPM_LIB_ERROR;
> +
> + /*
> + * Found the algorithm (bank) that matches, and enable all PCR
> + * bits.
> + * TODO: only select the bits needed
> + */
> + for (j = 0; j < ARRAY_SIZE(hash_algo_list); j++) {
> + if (hash_algo_list[j].hash_alg != sel->hash)
> + continue;
> +
> + if (algo_mask & hash_algo_list[j].hash_mask)
> + pad = 0xff;
> + }
> +
> + for (j = 0; j < sel->size_of_select; j++)
> + sel->pcr_select[j] = pad;
> +
> + log_info("set bank[%d] %s %s\n", i,
> + tpm2_algorithm_name(sel->hash),
> + tpm2_is_active_bank(sel) ? "on" : "off");
> +
> + *pcr_len += sizeof(sel->hash) + sizeof(sel->size_of_select) +
> + sel->size_of_select;
> + }
> +
> + return 0;
> +}
> +
> +u32 tpm2_send_pcr_allocate(struct udevice *dev, const char *pw,
> + const ssize_t pw_sz, struct tpml_pcr_selection
> *pcr,
> + u32 pcr_len)
> +{
> + /* Length of the message header, up to start of password */
> + uint offset = 27;
> + u8 command_v2[COMMAND_BUFFER_SIZE] = {
> + tpm_u16(TPM2_ST_SESSIONS), /* TAG */
> + tpm_u32(offset + pw_sz + pcr_len), /* Length */
> + tpm_u32(TPM2_CC_PCR_ALLOCATE), /* Command code */
> +
> + /* handles 4 bytes */
> + tpm_u32(TPM2_RH_PLATFORM), /* Primary platform seed */
> +
> + /* AUTH_SESSION */
> + tpm_u32(9 + pw_sz), /* 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(pw_sz), /* Size of <hmac/password> */
> + /* STRING(pw) <hmac/password> (if any) */
> +
> + /* TPML_PCR_SELECTION */
> + };
> + u8 response[COMMAND_BUFFER_SIZE];
> + size_t response_len = COMMAND_BUFFER_SIZE;
> + u32 i;
> + int ret;
> +
> + /*
> + * Fill the command structure starting from the first buffer:
> + * the password (if any)
> + */
> + if (pack_byte_string(command_v2, sizeof(command_v2), "s", offset, pw,
> + pw_sz))
> + return TPM_LIB_ERROR;
> +
> + offset += pw_sz;
> +
> + /* Pack the count field */
> + if (pack_byte_string(command_v2, sizeof(command_v2), "d", offset,
> pcr->count))
> + return TPM_LIB_ERROR;
> +
> + offset += sizeof(pcr->count);
> +
> + /* Pack each tpms_pcr_selection */
> + for (i = 0; i < pcr->count; i++) {
> + struct tpms_pcr_selection *sel = &pcr->selection[i];
> +
> + /* Pack hash (16-bit) */
> + if (pack_byte_string(command_v2, sizeof(command_v2), "w",
> offset,
> + sel->hash))
> + return TPM_LIB_ERROR;
> +
> + offset += sizeof(sel->hash);
> +
> + /* Pack size_of_select (8-bit) */
> + if (pack_byte_string(command_v2, sizeof(command_v2), "b",
> offset,
> + sel->size_of_select))
> + return TPM_LIB_ERROR;
> +
> + offset += sizeof(sel->size_of_select);
> +
> + /* Pack pcr_select array */
> + if (pack_byte_string(command_v2, sizeof(command_v2), "s",
> offset,
> + sel->pcr_select, sel->size_of_select))
> + return TPM_LIB_ERROR;
> +
> + offset += sel->size_of_select;
> + }
> +
> + ret = tpm_sendrecv_command(dev, command_v2, response, &response_len);
> + if (!ret)
> + tpm_init(dev);
> +
> + return ret;
> +}
> +
> static int tpm2_get_num_pcr(struct udevice *dev, u32 *num_pcr)
> {
> u8 response[(sizeof(struct tpms_capability_data) -
> --
> 2.25.1
>
Acked-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
