tpm: add dictionary attack mitigation commands support

Add support for the TPM2_DictionaryAttackParameters and
TPM2_DictionaryAttackLockReset commands.

Change the command file and the help accordingly.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

cmd/tpm-v2.c

@@ -181,6 +181,59 @@ unmap_data:
 	return report_return_code(rc);
 }
 
+static int do_tpm_dam_reset(cmd_tbl_t *cmdtp, int flag, int argc,
+			    char *const argv[])
+{
+	const char *pw = (argc < 2) ? NULL : argv[1];
+	const ssize_t pw_sz = pw ? strlen(pw) : 0;
+
+	if (argc > 2)
+		return CMD_RET_USAGE;
+
+	if (pw_sz > TPM2_DIGEST_LEN)
+		return -EINVAL;
+
+	return report_return_code(tpm2_dam_reset(pw, pw_sz));
+}
+
+static int do_tpm_dam_parameters(cmd_tbl_t *cmdtp, int flag, int argc,
+				 char *const argv[])
+{
+	const char *pw = (argc < 5) ? NULL : argv[4];
+	const ssize_t pw_sz = pw ? strlen(pw) : 0;
+	/*
+	 * No Dictionary Attack Mitigation (DAM) means:
+	 * maxtries = 0xFFFFFFFF, recovery_time = 1, lockout_recovery = 0
+	 */
+	unsigned long int max_tries;
+	unsigned long int recovery_time;
+	unsigned long int lockout_recovery;
+
+	if (argc < 4 || argc > 5)
+		return CMD_RET_USAGE;
+
+	if (pw_sz > TPM2_DIGEST_LEN)
+		return -EINVAL;
+
+	if (strict_strtoul(argv[1], 0, &max_tries))
+		return CMD_RET_USAGE;
+
+	if (strict_strtoul(argv[2], 0, &recovery_time))
+		return CMD_RET_USAGE;
+
+	if (strict_strtoul(argv[3], 0, &lockout_recovery))
+		return CMD_RET_USAGE;
+
+	log(LOGC_NONE, LOGL_INFO, "Changing dictionary attack parameters:\n");
+	log(LOGC_NONE, LOGL_INFO, "- maxTries: %lu", max_tries);
+	log(LOGC_NONE, LOGL_INFO, "- recoveryTime: %lu\n", recovery_time);
+	log(LOGC_NONE, LOGL_INFO, "- lockoutRecovery: %lu\n", lockout_recovery);
+
+	return report_return_code(tpm2_dam_parameters(pw, pw_sz, max_tries,
+						      recovery_time,
+						      lockout_recovery));
+}
+
 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, "", ""),
@@ -190,6 +243,8 @@ static cmd_tbl_t tpm2_commands[] = {
 	U_BOOT_CMD_MKENT(pcr_extend, 0, 1, do_tpm2_pcr_extend, "", ""),
 	U_BOOT_CMD_MKENT(pcr_read, 0, 1, do_tpm_pcr_read, "", ""),
 	U_BOOT_CMD_MKENT(get_capability, 0, 1, do_tpm_get_capability, "", ""),
+	U_BOOT_CMD_MKENT(dam_reset, 0, 1, do_tpm_dam_reset, "", ""),
+	U_BOOT_CMD_MKENT(dam_parameters, 0, 1, do_tpm_dam_parameters, "", ""),
 };
 
 cmd_tbl_t *get_tpm_commands(unsigned int *size)
@@ -236,4 +291,16 @@ U_BOOT_CMD(tpm, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue a TPMv2.x command",
 "    <property>: property\n"
 "    <addr>: address to store <count> entries of 4 bytes\n"
 "    <count>: number of entries to retrieve\n"
+"  dam_reset_counter [<password>]\n"
+"    - If the TPM is not in a LOCKOUT state, reset the internal error\n"
+"      counter (TPMv2 only)\n"
+"  dam_set_parameters <maxTries> <recoveryTime> <lockoutRecovery> [<password>]\n"
+"    - If the TPM is not in a LOCKOUT state, set the dictionary attack\n"
+"      parameters:\n"
+"          * maxTries: maximum number of failures before lockout.\n"
+"                          0 means always locking.\n"
+"          * recoveryTime: time before decrementation of the error counter,\n"
+"                          0 means no lockout.\n"
+"          * lockoutRecovery: time of a lockout (before the next try)\n"
+"                          0 means a reboot is needed.\n"
 );

include/tpm-v2.h

@@ -191,4 +191,29 @@ u32 tpm2_pcr_read(u32 idx, unsigned int idx_min_sz, void *data,
 u32 tpm2_get_capability(u32 capability, u32 property, void *buf,
 			size_t prop_count);
 
+/**
+ * Issue a TPM2_DictionaryAttackLockReset command.
+ *
+ * @pw		Password
+ * @pw_sz	Length of the password
+ *
+ * @return code of the operation
+ */
+u32 tpm2_dam_reset(const char *pw, const ssize_t pw_sz);
+
+/**
+ * Issue a TPM2_DictionaryAttackParameters command.
+ *
+ * @pw		Password
+ * @pw_sz	Length of the password
+ * @max_tries	Count of authorizations before lockout
+ * @recovery_time Time before decrementation of the failure count
+ * @lockout_recovery Time to wait after a lockout
+ *
+ * @return code of the operation
+ */
+u32 tpm2_dam_parameters(const char *pw, const ssize_t pw_sz,
+			unsigned int max_tries, unsigned int recovery_time,
+			unsigned int lockout_recovery);
+
 #endif /* __TPM_V2_H */

lib/tpm-v2.c

@@ -190,3 +190,86 @@ u32 tpm2_get_capability(u32 capability, u32 property, void *buf,
 
 	return 0;
 }
+
+u32 tpm2_dam_reset(const char *pw, const ssize_t pw_sz)
+{
+	u8 command_v2[COMMAND_BUFFER_SIZE] = {
+		tpm_u16(TPM2_ST_SESSIONS),	/* TAG */
+		tpm_u32(27 + pw_sz),		/* Length */
+		tpm_u32(TPM2_CC_DAM_RESET),	/* Command code */
+
+		/* HANDLE */
+		tpm_u32(TPM2_RH_LOCKOUT),	/* TPM resource handle */
+
+		/* 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) */
+	};
+	unsigned int offset = 27;
+	int ret;
+
+	/*
+	 * Fill the command structure starting from the first buffer:
+	 *     - the password (if any)
+	 */
+	ret = pack_byte_string(command_v2, sizeof(command_v2), "s",
+			       offset, pw, pw_sz);
+	offset += pw_sz;
+	if (ret)
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(command_v2, NULL, NULL);
+}
+
+u32 tpm2_dam_parameters(const char *pw, const ssize_t pw_sz,
+			unsigned int max_tries, unsigned int recovery_time,
+			unsigned int lockout_recovery)
+{
+	u8 command_v2[COMMAND_BUFFER_SIZE] = {
+		tpm_u16(TPM2_ST_SESSIONS),	/* TAG */
+		tpm_u32(27 + pw_sz + 12),	/* Length */
+		tpm_u32(TPM2_CC_DAM_PARAMETERS), /* Command code */
+
+		/* HANDLE */
+		tpm_u32(TPM2_RH_LOCKOUT),	/* TPM resource handle */
+
+		/* 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) */
+
+		/* LOCKOUT PARAMETERS */
+		/* tpm_u32(max_tries)		   Max tries (0, always lock) */
+		/* tpm_u32(recovery_time)	   Recovery time (0, no lock) */
+		/* tpm_u32(lockout_recovery)	   Lockout recovery */
+	};
+	unsigned int offset = 27;
+	int ret;
+
+	/*
+	 * Fill the command structure starting from the first buffer:
+	 *     - the password (if any)
+	 *     - max tries
+	 *     - recovery time
+	 *     - lockout recovery
+	 */
+	ret = pack_byte_string(command_v2, sizeof(command_v2), "sddd",
+			       offset, pw, pw_sz,
+			       offset + pw_sz, max_tries,
+			       offset + pw_sz + 4, recovery_time,
+			       offset + pw_sz + 8, lockout_recovery);
+	offset += pw_sz + 12;
+	if (ret)
+		return TPM_LIB_ERROR;
+
+	return tpm_sendrecv_command(command_v2, NULL, NULL);
+}