]> git.dujemihanovic.xyz Git - u-boot.git/commitdiff
dm: tpm: Add a 'tpmtest' command
authorSimon Glass <sjg@chromium.org>
Sun, 23 Aug 2015 00:31:42 +0000 (18:31 -0600)
committerSimon Glass <sjg@chromium.org>
Mon, 31 Aug 2015 13:57:29 +0000 (07:57 -0600)
These tests come from Chrome OS code. They are not particularly tidy but can
be useful for checking that the TPM is behaving correctly. Some knowledge of
TPM operation is required to use these.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Christophe Ricard<christophe-h.ricard@st.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
common/Kconfig
common/Makefile
common/cmd_tpm_test.c [new file with mode: 0644]

index bacc4e01cda3ffcc4f7b56fb765768f99b8ff5e3..2c42b8e4d0346e339543e908f8d76636f39b7332 100644 (file)
@@ -635,6 +635,16 @@ config CMD_TPM
          command requires a suitable TPM on your board and the correct driver
          must be enabled.
 
+config CMD_TPM_TEST
+       bool "Enable the 'tpm test' command"
+       depends on CMD_TPM
+       help
+         This provides a a series of tests to confirm that the TPM is working
+         correctly. The tests cover initialisation, non-volatile RAM, extend,
+         global lock and checking that timing is within expectations. The
+         tests pass correctly on Infineon TPMs but may need to be adjusted
+         for other devices.
+
 endmenu
 
 endmenu
index dc82433e90dee24e41423a1e7042313126c24d79..f4ba8782f543594a94c0ee995f293875b4ca1a20 100644 (file)
@@ -169,6 +169,7 @@ obj-$(CONFIG_CMD_TIME) += cmd_time.o
 obj-$(CONFIG_CMD_TRACE) += cmd_trace.o
 obj-$(CONFIG_SYS_HUSH_PARSER) += cmd_test.o
 obj-$(CONFIG_CMD_TPM) += cmd_tpm.o
+obj-$(CONFIG_CMD_TPM_TEST) += cmd_tpm_test.o
 obj-$(CONFIG_CMD_TSI148) += cmd_tsi148.o
 obj-$(CONFIG_CMD_UBI) += cmd_ubi.o
 obj-$(CONFIG_CMD_UBIFS) += cmd_ubifs.o
diff --git a/common/cmd_tpm_test.c b/common/cmd_tpm_test.c
new file mode 100644 (file)
index 0000000..65332d1
--- /dev/null
@@ -0,0 +1,564 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <environment.h>
+#include <tpm.h>
+
+/* Prints error and returns on failure */
+#define TPM_CHECK(tpm_command) do { \
+       uint32_t result; \
+       \
+       result = (tpm_command); \
+       if (result != TPM_SUCCESS) { \
+               printf("TEST FAILED: line %d: " #tpm_command ": 0x%x\n", \
+                       __LINE__, result); \
+               return result; \
+       } \
+} while (0)
+
+#define INDEX0                 0xda70
+#define INDEX1                 0xda71
+#define INDEX2                 0xda72
+#define INDEX3                 0xda73
+#define INDEX_INITIALISED      0xda80
+#define PHYS_PRESENCE          4
+#define PRESENCE               8
+
+static uint32_t TlclStartupIfNeeded(void)
+{
+       uint32_t result = tpm_startup(TPM_ST_CLEAR);
+
+       return result == TPM_INVALID_POSTINIT ? TPM_SUCCESS : result;
+}
+
+static int test_timer(void)
+{
+       printf("get_timer(0) = %lu\n", get_timer(0));
+       return 0;
+}
+
+static uint32_t tpm_get_flags(uint8_t *disable, uint8_t *deactivated,
+                             uint8_t *nvlocked)
+{
+       struct tpm_permanent_flags pflags;
+       uint32_t result;
+
+       result = tpm_get_permanent_flags(&pflags);
+       if (result)
+               return result;
+       if (disable)
+               *disable = pflags.disable;
+       if (deactivated)
+               *deactivated = pflags.deactivated;
+       if (nvlocked)
+               *nvlocked = pflags.nv_locked;
+       debug("TPM: Got flags disable=%d, deactivated=%d, nvlocked=%d\n",
+             pflags.disable, pflags.deactivated, pflags.nv_locked);
+
+       return 0;
+}
+
+static uint32_t tpm_set_global_lock(void)
+{
+       uint32_t x;
+
+       debug("TPM: Set global lock\n");
+       return tpm_nv_write_value(INDEX0, (uint8_t *)&x, 0);
+}
+
+static uint32_t tpm_nv_write_value_lock(uint32_t index)
+{
+       debug("TPM: Write lock 0x%x\n", index);
+
+       return tpm_nv_write_value(index, NULL, 0);
+}
+
+static uint32_t tpm_nv_set_locked(void)
+{
+       debug("TPM: Set NV locked\n");
+
+       return tpm_nv_define_space(TPM_NV_INDEX_LOCK, 0, 0);
+}
+
+static int tpm_is_owned(void)
+{
+       uint8_t response[TPM_PUBEK_SIZE];
+       uint32_t result;
+
+       result = tpm_read_pubek(response, sizeof(response));
+
+       return result != TPM_SUCCESS;
+}
+
+static int test_early_extend(void)
+{
+       uint8_t value_in[20];
+       uint8_t value_out[20];
+
+       printf("Testing earlyextend ...");
+       tpm_init();
+       TPM_CHECK(tpm_startup(TPM_ST_CLEAR));
+       TPM_CHECK(tpm_continue_self_test());
+       TPM_CHECK(tpm_extend(1, value_in, value_out));
+       printf("done\n");
+       return 0;
+}
+
+static int test_early_nvram(void)
+{
+       uint32_t x;
+
+       printf("Testing earlynvram ...");
+       tpm_init();
+       TPM_CHECK(tpm_startup(TPM_ST_CLEAR));
+       TPM_CHECK(tpm_continue_self_test());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_nv_read_value(INDEX0, (uint8_t *)&x, sizeof(x)));
+       printf("done\n");
+       return 0;
+}
+
+static int test_early_nvram2(void)
+{
+       uint32_t x;
+
+       printf("Testing earlynvram2 ...");
+       tpm_init();
+       TPM_CHECK(tpm_startup(TPM_ST_CLEAR));
+       TPM_CHECK(tpm_continue_self_test());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_nv_write_value(INDEX0, (uint8_t *)&x, sizeof(x)));
+       printf("done\n");
+       return 0;
+}
+
+static int test_enable(void)
+{
+       uint8_t disable = 0, deactivated = 0;
+
+       printf("Testing enable ...\n");
+       tpm_init();
+       TPM_CHECK(TlclStartupIfNeeded());
+       TPM_CHECK(tpm_self_test_full());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_get_flags(&disable, &deactivated, NULL));
+       printf("\tdisable is %d, deactivated is %d\n", disable, deactivated);
+       TPM_CHECK(tpm_physical_enable());
+       TPM_CHECK(tpm_physical_set_deactivated(0));
+       TPM_CHECK(tpm_get_flags(&disable, &deactivated, NULL));
+       printf("\tdisable is %d, deactivated is %d\n", disable, deactivated);
+       if (disable == 1 || deactivated == 1)
+               printf("\tfailed to enable or activate\n");
+       printf("\tdone\n");
+       return 0;
+}
+
+#define reboot() do { \
+       printf("\trebooting...\n"); \
+       reset_cpu(0); \
+} while (0)
+
+static int test_fast_enable(void)
+{
+       uint8_t disable = 0, deactivated = 0;
+       int i;
+
+       printf("Testing fastenable ...\n");
+       tpm_init();
+       TPM_CHECK(TlclStartupIfNeeded());
+       TPM_CHECK(tpm_self_test_full());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_get_flags(&disable, &deactivated, NULL));
+       printf("\tdisable is %d, deactivated is %d\n", disable, deactivated);
+       for (i = 0; i < 2; i++) {
+               TPM_CHECK(tpm_force_clear());
+               TPM_CHECK(tpm_get_flags(&disable, &deactivated, NULL));
+               printf("\tdisable is %d, deactivated is %d\n", disable,
+                      deactivated);
+               assert(disable == 1 && deactivated == 1);
+               TPM_CHECK(tpm_physical_enable());
+               TPM_CHECK(tpm_physical_set_deactivated(0));
+               TPM_CHECK(tpm_get_flags(&disable, &deactivated, NULL));
+               printf("\tdisable is %d, deactivated is %d\n", disable,
+                      deactivated);
+               assert(disable == 0 && deactivated == 0);
+       }
+       printf("\tdone\n");
+       return 0;
+}
+
+static int test_global_lock(void)
+{
+       uint32_t zero = 0;
+       uint32_t result;
+       uint32_t x;
+
+       printf("Testing globallock ...\n");
+       tpm_init();
+       TPM_CHECK(TlclStartupIfNeeded());
+       TPM_CHECK(tpm_self_test_full());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_nv_read_value(INDEX0, (uint8_t *)&x, sizeof(x)));
+       TPM_CHECK(tpm_nv_write_value(INDEX0, (uint8_t *)&zero,
+                                    sizeof(uint32_t)));
+       TPM_CHECK(tpm_nv_read_value(INDEX1, (uint8_t *)&x, sizeof(x)));
+       TPM_CHECK(tpm_nv_write_value(INDEX1, (uint8_t *)&zero,
+                                    sizeof(uint32_t)));
+       TPM_CHECK(tpm_set_global_lock());
+       /* Verifies that write to index0 fails */
+       x = 1;
+       result = tpm_nv_write_value(INDEX0, (uint8_t *)&x, sizeof(x));
+       assert(result == TPM_AREA_LOCKED);
+       TPM_CHECK(tpm_nv_read_value(INDEX0, (uint8_t *)&x, sizeof(x)));
+       assert(x == 0);
+       /* Verifies that write to index1 is still possible */
+       x = 2;
+       TPM_CHECK(tpm_nv_write_value(INDEX1, (uint8_t *)&x, sizeof(x)));
+       TPM_CHECK(tpm_nv_read_value(INDEX1, (uint8_t *)&x, sizeof(x)));
+       assert(x == 2);
+       /* Turns off PP */
+       tpm_tsc_physical_presence(PHYS_PRESENCE);
+       /* Verifies that write to index1 fails */
+       x = 3;
+       result = tpm_nv_write_value(INDEX1, (uint8_t *)&x, sizeof(x));
+       assert(result == TPM_BAD_PRESENCE);
+       TPM_CHECK(tpm_nv_read_value(INDEX1, (uint8_t *)&x, sizeof(x)));
+       assert(x == 2);
+       printf("\tdone\n");
+       return 0;
+}
+
+static int test_lock(void)
+{
+       printf("Testing lock ...\n");
+       tpm_init();
+       tpm_startup(TPM_ST_CLEAR);
+       tpm_self_test_full();
+       tpm_tsc_physical_presence(PRESENCE);
+       tpm_nv_write_value_lock(INDEX0);
+       printf("\tLocked 0x%x\n", INDEX0);
+       printf("\tdone\n");
+       return 0;
+}
+
+static void initialise_spaces(void)
+{
+       uint32_t zero = 0;
+       uint32_t perm = TPM_NV_PER_WRITE_STCLEAR | TPM_NV_PER_PPWRITE;
+
+       printf("\tInitialising spaces\n");
+       tpm_nv_set_locked();  /* useful only the first time */
+       tpm_nv_define_space(INDEX0, perm, 4);
+       tpm_nv_write_value(INDEX0, (uint8_t *)&zero, 4);
+       tpm_nv_define_space(INDEX1, perm, 4);
+       tpm_nv_write_value(INDEX1, (uint8_t *)&zero, 4);
+       tpm_nv_define_space(INDEX2, perm, 4);
+       tpm_nv_write_value(INDEX2, (uint8_t *)&zero, 4);
+       tpm_nv_define_space(INDEX3, perm, 4);
+       tpm_nv_write_value(INDEX3, (uint8_t *)&zero, 4);
+       perm = TPM_NV_PER_READ_STCLEAR | TPM_NV_PER_WRITE_STCLEAR |
+               TPM_NV_PER_PPWRITE;
+       tpm_nv_define_space(INDEX_INITIALISED, perm, 1);
+}
+
+static int test_readonly(void)
+{
+       uint8_t c;
+       uint32_t index_0, index_1, index_2, index_3;
+       int read0, read1, read2, read3;
+
+       printf("Testing readonly ...\n");
+       tpm_init();
+       tpm_startup(TPM_ST_CLEAR);
+       tpm_self_test_full();
+       tpm_tsc_physical_presence(PRESENCE);
+       /*
+        * Checks if initialisation has completed by trying to read-lock a
+        * space that's created at the end of initialisation
+        */
+       if (tpm_nv_read_value(INDEX_INITIALISED, &c, 0) == TPM_BADINDEX) {
+               /* The initialisation did not complete */
+               initialise_spaces();
+       }
+
+       /* Checks if spaces are OK or messed up */
+       read0 = tpm_nv_read_value(INDEX0, (uint8_t *)&index_0, sizeof(index_0));
+       read1 = tpm_nv_read_value(INDEX1, (uint8_t *)&index_1, sizeof(index_1));
+       read2 = tpm_nv_read_value(INDEX2, (uint8_t *)&index_2, sizeof(index_2));
+       read3 = tpm_nv_read_value(INDEX3, (uint8_t *)&index_3, sizeof(index_3));
+       if (read0 || read1 || read2 || read3) {
+               printf("Invalid contents\n");
+               return 0;
+       }
+
+       /*
+        * Writes space, and locks it.  Then attempts to write again.
+        * I really wish I could use the imperative.
+        */
+       index_0 += 1;
+       if (tpm_nv_write_value(INDEX0, (uint8_t *)&index_0, sizeof(index_0) !=
+               TPM_SUCCESS)) {
+               error("\tcould not write index 0\n");
+       }
+       tpm_nv_write_value_lock(INDEX0);
+       if (tpm_nv_write_value(INDEX0, (uint8_t *)&index_0, sizeof(index_0)) ==
+                       TPM_SUCCESS)
+               error("\tindex 0 is not locked\n");
+
+       printf("\tdone\n");
+       return 0;
+}
+
+static int test_redefine_unowned(void)
+{
+       uint32_t perm;
+       uint32_t result;
+       uint32_t x;
+
+       printf("Testing redefine_unowned ...");
+       tpm_init();
+       TPM_CHECK(TlclStartupIfNeeded());
+       TPM_CHECK(tpm_self_test_full());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       assert(!tpm_is_owned());
+
+       /* Ensures spaces exist. */
+       TPM_CHECK(tpm_nv_read_value(INDEX0, (uint8_t *)&x, sizeof(x)));
+       TPM_CHECK(tpm_nv_read_value(INDEX1, (uint8_t *)&x, sizeof(x)));
+
+       /* Redefines spaces a couple of times. */
+       perm = TPM_NV_PER_PPWRITE | TPM_NV_PER_GLOBALLOCK;
+       TPM_CHECK(tpm_nv_define_space(INDEX0, perm, 2 * sizeof(uint32_t)));
+       TPM_CHECK(tpm_nv_define_space(INDEX0, perm, sizeof(uint32_t)));
+       perm = TPM_NV_PER_PPWRITE;
+       TPM_CHECK(tpm_nv_define_space(INDEX1, perm, 2 * sizeof(uint32_t)));
+       TPM_CHECK(tpm_nv_define_space(INDEX1, perm, sizeof(uint32_t)));
+
+       /* Sets the global lock */
+       tpm_set_global_lock();
+
+       /* Verifies that index0 cannot be redefined */
+       result = tpm_nv_define_space(INDEX0, perm, sizeof(uint32_t));
+       assert(result == TPM_AREA_LOCKED);
+
+       /* Checks that index1 can */
+       TPM_CHECK(tpm_nv_define_space(INDEX1, perm, 2 * sizeof(uint32_t)));
+       TPM_CHECK(tpm_nv_define_space(INDEX1, perm, sizeof(uint32_t)));
+
+       /* Turns off PP */
+       tpm_tsc_physical_presence(PHYS_PRESENCE);
+
+       /* Verifies that neither index0 nor index1 can be redefined */
+       result = tpm_nv_define_space(INDEX0, perm, sizeof(uint32_t));
+       assert(result == TPM_BAD_PRESENCE);
+       result = tpm_nv_define_space(INDEX1, perm, sizeof(uint32_t));
+       assert(result == TPM_BAD_PRESENCE);
+
+       printf("done\n");
+       return 0;
+}
+
+#define PERMPPGL (TPM_NV_PER_PPWRITE | TPM_NV_PER_GLOBALLOCK)
+#define PERMPP TPM_NV_PER_PPWRITE
+
+static int test_space_perm(void)
+{
+       uint32_t perm;
+
+       printf("Testing spaceperm ...");
+       tpm_init();
+       TPM_CHECK(TlclStartupIfNeeded());
+       TPM_CHECK(tpm_continue_self_test());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_get_permissions(INDEX0, &perm));
+       assert((perm & PERMPPGL) == PERMPPGL);
+       TPM_CHECK(tpm_get_permissions(INDEX1, &perm));
+       assert((perm & PERMPP) == PERMPP);
+       printf("done\n");
+       return 0;
+}
+
+static int test_startup(void)
+{
+       uint32_t result;
+       printf("Testing startup ...\n");
+
+       tpm_init();
+       result = tpm_startup(TPM_ST_CLEAR);
+       if (result != 0 && result != TPM_INVALID_POSTINIT)
+               printf("\ttpm startup failed with 0x%x\n", result);
+       result = tpm_get_flags(NULL, NULL, NULL);
+       if (result != 0)
+               printf("\ttpm getflags failed with 0x%x\n", result);
+       printf("\texecuting SelfTestFull\n");
+       tpm_self_test_full();
+       result = tpm_get_flags(NULL, NULL, NULL);
+       if (result != 0)
+               printf("\ttpm getflags failed with 0x%x\n", result);
+       printf("\tdone\n");
+       return 0;
+}
+
+/*
+ * Runs [op] and ensures it returns success and doesn't run longer than
+ * [time_limit] in milliseconds.
+ */
+#define TTPM_CHECK(op, time_limit) do { \
+       ulong start, time; \
+       uint32_t __result; \
+       \
+       start = get_timer(0); \
+       __result = op; \
+       if (__result != TPM_SUCCESS) { \
+               printf("\t" #op ": error 0x%x\n", __result); \
+               return -1; \
+       } \
+       time = get_timer(start); \
+       printf("\t" #op ": %lu ms\n", time); \
+       if (time > (ulong)time_limit) { \
+               printf("\t" #op " exceeded " #time_limit " ms\n"); \
+       } \
+} while (0)
+
+
+static int test_timing(void)
+{
+       uint32_t x;
+       uint8_t in[20], out[20];
+
+       printf("Testing timing ...");
+       tpm_init();
+       TTPM_CHECK(TlclStartupIfNeeded(), 50);
+       TTPM_CHECK(tpm_continue_self_test(), 100);
+       TTPM_CHECK(tpm_self_test_full(), 1000);
+       TTPM_CHECK(tpm_tsc_physical_presence(PRESENCE), 100);
+       TTPM_CHECK(tpm_nv_write_value(INDEX0, (uint8_t *)&x, sizeof(x)), 100);
+       TTPM_CHECK(tpm_nv_read_value(INDEX0, (uint8_t *)&x, sizeof(x)), 100);
+       TTPM_CHECK(tpm_extend(0, in, out), 200);
+       TTPM_CHECK(tpm_set_global_lock(), 50);
+       TTPM_CHECK(tpm_tsc_physical_presence(PHYS_PRESENCE), 100);
+       printf("done\n");
+       return 0;
+}
+
+#define TPM_MAX_NV_WRITES_NOOWNER 64
+
+static int test_write_limit(void)
+{
+       printf("Testing writelimit ...\n");
+       int i;
+       uint32_t result;
+
+       tpm_init();
+       TPM_CHECK(TlclStartupIfNeeded());
+       TPM_CHECK(tpm_self_test_full());
+       TPM_CHECK(tpm_tsc_physical_presence(PRESENCE));
+       TPM_CHECK(tpm_force_clear());
+       TPM_CHECK(tpm_physical_enable());
+       TPM_CHECK(tpm_physical_set_deactivated(0));
+
+       for (i = 0; i < TPM_MAX_NV_WRITES_NOOWNER + 2; i++) {
+               printf("\twriting %d\n", i);
+               result = tpm_nv_write_value(INDEX0, (uint8_t *)&i, sizeof(i));
+               switch (result) {
+               case TPM_SUCCESS:
+                       break;
+               case TPM_MAXNVWRITES:
+                       assert(i >= TPM_MAX_NV_WRITES_NOOWNER);
+               default:
+                       error("\tunexpected error code %d (0x%x)\n",
+                             result, result);
+               }
+       }
+
+       /* Reset write count */
+       TPM_CHECK(tpm_force_clear());
+       TPM_CHECK(tpm_physical_enable());
+       TPM_CHECK(tpm_physical_set_deactivated(0));
+
+       /* Try writing again. */
+       TPM_CHECK(tpm_nv_write_value(INDEX0, (uint8_t *)&i, sizeof(i)));
+       printf("\tdone\n");
+       return 0;
+}
+
+#define VOIDTEST(XFUNC) \
+       int do_test_##XFUNC(cmd_tbl_t *cmd_tbl, int flag, int argc, \
+       char * const argv[]) \
+       { \
+               return test_##XFUNC(); \
+       }
+
+#define VOIDENT(XNAME) \
+       U_BOOT_CMD_MKENT(XNAME, 0, 1, do_test_##XNAME, "", ""),
+
+VOIDTEST(early_extend)
+VOIDTEST(early_nvram)
+VOIDTEST(early_nvram2)
+VOIDTEST(enable)
+VOIDTEST(fast_enable)
+VOIDTEST(global_lock)
+VOIDTEST(lock)
+VOIDTEST(readonly)
+VOIDTEST(redefine_unowned)
+VOIDTEST(space_perm)
+VOIDTEST(startup)
+VOIDTEST(timing)
+VOIDTEST(write_limit)
+VOIDTEST(timer)
+
+static cmd_tbl_t cmd_cros_tpm_sub[] = {
+       VOIDENT(early_extend)
+       VOIDENT(early_nvram)
+       VOIDENT(early_nvram2)
+       VOIDENT(enable)
+       VOIDENT(fast_enable)
+       VOIDENT(global_lock)
+       VOIDENT(lock)
+       VOIDENT(readonly)
+       VOIDENT(redefine_unowned)
+       VOIDENT(space_perm)
+       VOIDENT(startup)
+       VOIDENT(timing)
+       VOIDENT(write_limit)
+       VOIDENT(timer)
+};
+
+static int do_tpmtest(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+       cmd_tbl_t *c;
+
+       printf("argc = %d, argv = ", argc);
+       do {
+               int i = 0;
+
+               for (i = 0; i < argc; i++)
+                       printf(" %s", argv[i]);
+                       printf("\n------\n");
+               } while (0);
+       argc--;
+       argv++;
+       c = find_cmd_tbl(argv[0], cmd_cros_tpm_sub,
+                        ARRAY_SIZE(cmd_cros_tpm_sub));
+       return c ? c->cmd(cmdtp, flag, argc, argv) : cmd_usage(cmdtp);
+}
+
+U_BOOT_CMD(tpmtest, 2, 1, do_tpmtest, "TPM tests",
+       "\n\tearly_extend\n"
+       "\tearly_nvram\n"
+       "\tearly_nvram2\n"
+       "\tenable\n"
+       "\tfast_enable\n"
+       "\tglobal_lock\n"
+       "\tlock\n"
+       "\treadonly\n"
+       "\tredefine_unowned\n"
+       "\tspace_perm\n"
+       "\tstartup\n"
+       "\ttiming\n"
+       "\twrite_limit\n");