Remove kernel backup space

firmware/lib/rollback_index.c

Index: firmware/lib/rollback_index.c
diff --git a/firmware/lib/rollback_index.c b/firmware/lib/rollback_index.c
index f368355fbea65dcb2c7348cda2993e6e3e7fdeeb..7467bedc2fcfd80d5d20b0c82a73e2dbcd1c011d 100644
--- a/firmware/lib/rollback_index.c
+++ b/firmware/lib/rollback_index.c
@@ -77,16 +77,16 @@ static uint32_t WriteSpaceFirmware(const RollbackSpaceFirmware* rsf) {
   return SafeWrite(FIRMWARE_NV_INDEX, rsf, sizeof(RollbackSpaceFirmware));
 }
 
+#ifndef DISABLE_ROLLBACK_TPM
 static uint32_t ReadSpaceKernel(RollbackSpaceKernel* rsk) {
   return TlclRead(KERNEL_NV_INDEX, rsk, sizeof(RollbackSpaceKernel));
 }
+#endif
 
 static uint32_t WriteSpaceKernel(const RollbackSpaceKernel* rsk) {
   return SafeWrite(KERNEL_NV_INDEX, rsk, sizeof(RollbackSpaceKernel));
 }
 
-
-
 /* Creates the NVRAM spaces, and sets their initial values as needed. */
 static uint32_t InitializeSpaces(RollbackSpaceFirmware* rsf,
                                  RollbackSpaceKernel* rsk) {
@@ -110,9 +110,6 @@ static uint32_t InitializeSpaces(RollbackSpaceFirmware* rsf,
 
   /* Initialize the firmware and kernel spaces */
   Memcpy(rsf, &rsf_init, sizeof(RollbackSpaceFirmware));
-  /* Initialize the backup copy of the kernel space to the same data
-   * as the kernel space */
-  Memcpy(&rsf->kernel_backup, &rsk_init, sizeof(RollbackSpaceKernel));
   Memcpy(rsk, &rsk_init, sizeof(RollbackSpaceKernel));
 
   /* Define and set firmware and kernel spaces */
@@ -149,14 +146,11 @@ static uint32_t InitializeSpaces(RollbackSpaceFirmware* rsf,
 uint32_t SetupTPM(int recovery_mode, int developer_mode,
                   RollbackSpaceFirmware* rsf) {
 
-  RollbackSpaceKernel rsk;
   int rsf_dirty = 0;
   uint8_t new_flags = 0;
-
   uint8_t disable;
   uint8_t deactivated;
   uint32_t result;
-  uint32_t perms;
 
   VBDEBUG(("TPM: SetupTPM(r%d, d%d)\n", recovery_mode, developer_mode));
 
@@ -188,6 +182,8 @@ uint32_t SetupTPM(int recovery_mode, int developer_mode,
   /* Read the firmware space. */
   result = ReadSpaceFirmware(rsf);
   if (TPM_E_BADINDEX == result) {
+    RollbackSpaceKernel rsk;
+
     /* This is the first time we've run, and the TPM has not been
      * initialized.  Initialize it. */
     VBDEBUG(("TPM: Not initialized yet.\n"));
@@ -199,40 +195,6 @@ uint32_t SetupTPM(int recovery_mode, int developer_mode,
   VBDEBUG(("TPM: Firmware space sv%d f%x v%x\n",
            rsf->struct_version, rsf->flags, rsf->fw_versions));
 
-  /* Read the kernel space and verify its permissions.  If the kernel
-   * space has the wrong permission, or it doesn't contain the right
-   * identifier, we give up.  This will need to be fixed by the
-   * recovery kernel.  We have to worry about this because at any time
-   * (even with PP turned off) the TPM owner can remove and redefine a
-   * PP-protected space (but not write to it). */
-  RETURN_ON_FAILURE(ReadSpaceKernel(&rsk));
-  RETURN_ON_FAILURE(TlclGetPermissions(KERNEL_NV_INDEX, &perms));
-  if (TPM_NV_PER_PPWRITE != perms || ROLLBACK_SPACE_KERNEL_UID != rsk.uid)
-    return TPM_E_CORRUPTED_STATE;
-  VBDEBUG(("TPM: Kernel space sv%d v%x\n",
-           rsk.struct_version, rsk.kernel_versions));
-
-  /* If the kernel space and its backup are different, we need to copy
-   * one to the other.  Which one we copy depends on whether the
-   * use-backup flag is set. */
-  if (0 != Memcmp(&rsk, &rsf->kernel_backup, sizeof(RollbackSpaceKernel))) {
-    VBDEBUG(("TPM: kernel space and backup are different\n"));
-
-    if (rsf->flags & FLAG_KERNEL_SPACE_USE_BACKUP) {
-      VBDEBUG(("TPM: use backup kernel space\n"));
-      Memcpy(&rsk, &rsf->kernel_backup, sizeof(RollbackSpaceKernel));
-      RETURN_ON_FAILURE(WriteSpaceKernel(&rsk));
-    } else if (rsk.kernel_versions < rsf->kernel_backup.kernel_versions) {
-      VBDEBUG(("TPM: kernel versions %x < backup versions %x\n",
-               rsk.kernel_versions, rsf->kernel_backup.kernel_versions));
-      return TPM_E_INTERNAL_INCONSISTENCY;
-    } else {
-      VBDEBUG(("TPM: copy kernel space to backup\n"));
-      Memcpy(&rsf->kernel_backup, &rsk, sizeof(RollbackSpaceKernel));
-      rsf_dirty = 1;
-    }
-  }
-
   /* Clear ownership if developer flag has toggled */
   if ((developer_mode ? FLAG_LAST_BOOT_DEVELOPER : 0) !=
       (rsf->flags & FLAG_LAST_BOOT_DEVELOPER)) {
@@ -243,11 +205,10 @@ uint32_t SetupTPM(int recovery_mode, int developer_mode,
   /* Update flags */
   if (developer_mode)
     new_flags |= FLAG_LAST_BOOT_DEVELOPER;
-  if (recovery_mode) {
-    new_flags |= FLAG_KERNEL_SPACE_USE_BACKUP;
+  if (recovery_mode)
     g_rollback_recovery_mode = 1;  /* Global variables are usable in
                                     * recovery mode */
-  }
+
   if (rsf->flags != new_flags) {
     rsf->flags = new_flags;
     rsf_dirty = 1;
@@ -323,7 +284,7 @@ uint32_t RollbackFirmwareSetup(int developer_mode, uint32_t* version) {
 
   RETURN_ON_FAILURE(SetupTPM(0, developer_mode, &rsf));
   *version = rsf.fw_versions;
-  VBDEBUG(("TPM: RollbackFirmwareSetup %x %x %x\n", (int)rsf.fw_versions));
+  VBDEBUG(("TPM: RollbackFirmwareSetup %x\n", (int)rsf.fw_versions));
   return TPM_SUCCESS;
 }
 
@@ -361,7 +322,19 @@ uint32_t RollbackKernelRead(uint32_t* version) {
     *version = 0;
   } else {
     RollbackSpaceKernel rsk;
+    uint32_t perms;
+
+    /* Read the kernel space and verify its permissions.  If the kernel
+     * space has the wrong permission, or it doesn't contain the right
+     * identifier, we give up.  This will need to be fixed by the
+     * recovery kernel.  We have to worry about this because at any time
+     * (even with PP turned off) the TPM owner can remove and redefine a
+     * PP-protected space (but not write to it). */
     RETURN_ON_FAILURE(ReadSpaceKernel(&rsk));
+    RETURN_ON_FAILURE(TlclGetPermissions(KERNEL_NV_INDEX, &perms));
+    if (TPM_NV_PER_PPWRITE != perms || ROLLBACK_SPACE_KERNEL_UID != rsk.uid)
+      return TPM_E_CORRUPTED_STATE;
+
     *version = rsk.kernel_versions;
     VBDEBUG(("TPM: RollbackKernelRead %x\n", (int)rsk.kernel_versions));
   }