[U-Boot] [PATCH v4 22/32] tpm: add dictionary attack mitigation commands support

Miquel Raynal
2018-05-15T09:57:18Z

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>
---
cmd/tpm-v2.c | 67 +++++++++++++++++++++++++++++++++++++++++++++
include/tpm-v2.h | 25 +++++++++++++++++
lib/tpm-v2.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 175 insertions(+)

diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
index 3599763e90..5e3ebc7984 100644
--- a/cmd/tpm-v2.c
+++ b/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"
);
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index 618026ce2a..4e182cf827 100644
--- a/include/tpm-v2.h
+++ b/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 */
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 330844ee31..5f1090eccb 100644
--- a/lib/tpm-v2.c
+++ b/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);
+}
--
2.14.1