tpm2-util: For NV index errors report EREMOTE to be able to continue

When we have many LUKS slots and not all are for our TPM, we can get an
NV index error when it's missing or has wrong content.
Instead of fully erroring out, map these encounters to EREMOTE like we
do for a foreign TPM key.

src/cryptsetup/cryptsetup-tokens/luks2-tpm2.c

@@ -112,7 +112,7 @@ int acquire_luks2_key(
                         srk,
                         ret_decrypted_key);
         if (r == -EREMOTE)
-                return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM.");
+                return log_error_errno(r, "TPM key integrity check failed or NV index unusable. Key enrolled in superblock most likely does not belong to this TPM.");
         if (r == -EILSEQ)
                 return log_error_errno(SYNTHETIC_ERRNO(ENOANO), "Bad PIN."); /* cryptsetup docs say we should return ENOANO on bad PIN */
         if (r == -ENOLCK)

src/shared/cryptsetup-tpm2.c

@@ -174,7 +174,7 @@ int acquire_tpm2_key(
                                 srk,
                                 ret_decrypted_key);
                 if (r == -EREMOTE)
-                        return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM.");
+                        return log_error_errno(r, "TPM key integrity check failed or NV index unusable. Key enrolled in superblock most likely does not belong to this TPM.");
                 if (ERRNO_IS_NEG_TPM2_UNSEAL_BAD_PCR(r))
                         return log_error_errno(r, "TPM policy does not match current system state. Either system has been tempered with or policy out-of-date: %m");
                 if (r == -ENOSTR)
@@ -229,7 +229,7 @@ int acquire_tpm2_key(
                                 srk,
                                 ret_decrypted_key);
                 if (r == -EREMOTE)
-                        return log_error_errno(r, "TPM key integrity check failed. Key enrolled in superblock most likely does not belong to this TPM.");
+                        return log_error_errno(r, "TPM key integrity check failed or NV index unusable. Key enrolled in superblock most likely does not belong to this TPM.");
                 if (ERRNO_IS_NEG_TPM2_UNSEAL_BAD_PCR(r))
                         return log_error_errno(r, "TPM policy does not match current system state. Either system has been tempered with or policy out-of-date: %m");
                 if (r == -ENOSTR)

src/shared/tpm2-util.c

@@ -4751,6 +4751,10 @@ int tpm2_policy_authorize_nv(
                                                                   * just put together */
                 return log_debug_errno(SYNTHETIC_ERRNO(EREMCHG),
                                        "Submitted policy does not match policy stored in PolicyAuthorizeNV.");
+        if ((rc & ~(TPM2_RC_N_MASK|TPM2_RC_P)) == TPM2_RC_HANDLE ||
+            rc == TPM2_RC_NV_UNINITIALIZED) /* NV index is missing, unwritten, or otherwise unusable for this policy (or: wrong authHandle/policySession). */
+                return log_debug_errno(SYNTHETIC_ERRNO(EREMOTE),
+                                       "NV index referenced by token is missing, unwritten, or unusable.");
         if (rc != TSS2_RC_SUCCESS)
                 return log_debug_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE),
                                        "Failed to add AuthorizeNV policy to TPM: %s",
@@ -6663,7 +6667,7 @@ int tpm2_unseal(Tpm2Context *c,
 
         /* Returns the following errors:
          *
-         *   -EREMOTE         → blob is from a different TPM
+         *   -EREMOTE         → blob is from a different TPM, or NV index referenced by policy is unusable
          *   -ENOSTR          → signature JSON has no matching entry for the current PCR policy
          *   -EDEADLK         → couldn't create primary key because authorization failure
          *   -ENOLCK          → TPM is in dictionary lockout mode