tpm: add TPM2_PCR_Allocate command
authorRaymond Mao <raymond.mao@linaro.org>
Mon, 27 Jan 2025 14:58:47 +0000 (06:58 -0800)
committerIlias Apalodimas <ilias.apalodimas@linaro.org>
Tue, 28 Jan 2025 06:58:41 +0000 (08:58 +0200)
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.mao@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
cmd/tpm-v2.c
include/tpm-v2.h
lib/tpm-v2.c

index a6d57ee..a62862e 100644 (file)
@@ -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"
 );
index f66a8e1..af3158f 100644 (file)
@@ -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
index 3946ac2..045b5dd 100644 (file)
@@ -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) -