tpmc: Make 'tpmc def' replace the existing space by default

In chromium:895549, we want to have consistent behavior of
'tpmc def' between TPM 1.2 and TPM 2.0.
In TPM 1.2, define space command will undefine the existing space,
and create a new one. So we make the 'tpmc def' act as this by
default.

Also, provide a option for whom may want to define a new space
only if it is not defined yet. It will return TPM error code
at that case.

BUG=chromium:895549
BRANCH=None
TEST=unit test; manually test:

 # For TPM 2.0 use AUTHREAD|AUTHWRITE
 tpmc tpmversion | grep 2.0 && export PERM=0x40004
 tpmc tpmversion | grep 1.2 && export PERM=0x1

 # Define the space
 tpmc def 0x1020 0x1 "$PERM"

 # Redefine the space, default will overwrite
 tpmc def 0x1020 0x1 "$PERM"
 # Expected: Success

 tpmc def 0x1020 0x1 "$PERM" --no-overwrite
 # Expected: output error for the space is already defined.
 # For TPM 2.0, it should output:
 #  command "def" failed with code 0x14c
 #  the TPM error code is unknown to this program
 # For TPM 1.2, it should output:
 #  The space is existing but --no-overwrite is set.

Change-Id: I9b4e742f2935578443ebcc69e91d0aebc84deed8
Reviewed-on: https://chromium-review.googlesource.com/1298098
Commit-Ready: Meng-Huan Yu <menghuan@chromium.org>
Tested-by: Meng-Huan Yu <menghuan@chromium.org>
Reviewed-by: Andrey Pronin <apronin@chromium.org>

1 files changed, 36 insertions, 3 deletions

diff --git a/utility/tpmc.c b/utility/tpmc.c
index 587e99ff..2e1e5180 100644
--- a/utility/tpmc.c
+++ b/utility/tpmc.c
@@ -167,10 +167,14 @@ static uint32_t HandlerDeactivate(void) {
 
 static uint32_t HandlerDefineSpace(void) {
   uint32_t index, size, perm;
-  if (nargs != 5) {
-    fprintf(stderr, "usage: tpmc def <index> <size> <perm>\n");
+  int overwrite = 1;
+
+  if (nargs != 5 && nargs != 6) {
+    fprintf(stderr, "usage: tpmc def <index> <size> <perm> "
+                    "[--no-overwrite])\n");
     exit(OTHER_ERROR);
   }
+
   if (HexStringToUint32(args[2], &index) != 0 ||
       HexStringToUint32(args[3], &size) != 0 ||
       HexStringToUint32(args[4], &perm) != 0) {
@@ -178,6 +182,32 @@ static uint32_t HandlerDefineSpace(void) {
             "32-bit hex (0x[0-9a-f]+)\n");
     exit(OTHER_ERROR);
   }
+
+  if (args[5] && strcmp(args[5], "--no-overwrite") == 0) {
+    overwrite = 0;
+  }
+
+#ifdef TPM2_MODE
+  // For TPM 2.0, DefineSpace will fail if the space already exists, so to
+  // support the default 'overwrite' mode, need to undefine the space first.
+  if (overwrite) {
+    TlclUndefineSpace(index);
+  }
+#else  /* ifndef TPM2_MODE */
+  // For TPM 1.2, we have to check the existing before calling DefineSpace(),
+  // since it will automaticly overwrite the existing space by default.
+  // Do nothing for TPM 2.0. We rely on DefineSpace() to return the appropriate
+  // error code.
+  if (!overwrite) {
+    uint32_t result , permissions;
+    result = TlclGetPermissions(index, &permissions);
+    if (!result) {
+      fprintf(stderr, "The space is existing but --no-overwrite is set.\n");
+      exit(OTHER_ERROR);
+    }
+  }
+#endif
+
   return TlclDefineSpace(index, perm, size);
 }
 
@@ -587,7 +617,10 @@ command_record command_table[] = {
     TPM_MODE_SELECT("set the bGlobalLock until reboot",
       "set rollback protection lock for R/W firmware until reboot"),
     TlclSetGlobalLock },
-  { "definespace", "def", "define a space (def <index> <size> <perm>)",
+  { "definespace", "def",
+    TPM_MODE_SELECT("define a space (def <index> <size> <perm>). ",
+        "define a space (def <index> <size> <perm> [--no-overwrite]). ")
+      "Default will overwrite if the space is defined.",
     HandlerDefineSpace },
   { "undefinespace", "undef",
     "undefine a space (undef <index>)"