tpm2: add TPM2_PCR_VALID()

src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c

@@ -271,7 +271,7 @@ _public_ int cryptsetup_token_validate(
                 }
 
                 u = json_variant_unsigned(e);
-                if (u >= TPM2_PCRS_MAX) {
+                if (!TPM2_PCR_VALID(u)) {
                         crypt_log_debug(cd, "TPM2 PCR number out of range.");
                         return 1;
                 }

src/cryptsetup/cryptsetup.c

@@ -438,7 +438,7 @@ static int parse_one_option(const char *option) {
                         }
 
                         pcr = r ? TPM_PCR_INDEX_VOLUME_KEY : UINT_MAX;
-                } else if (pcr >= TPM2_PCRS_MAX) {
+                } else if (!TPM2_PCR_VALID(pcr)) {
                         log_error("Selected TPM index for measurement %u outside of allowed range 0…%u, ignoring.", pcr, TPM2_PCRS_MAX-1);
                         return 0;
                 }

src/shared/tpm2-util.c

@@ -466,7 +466,7 @@ void tpm2_pcr_mask_to_selection(uint32_t mask, uint16_t bank, TPML_PCR_SELECTION
         assert(ret);
 
         /* We only do 24bit here, as that's what PC TPMs are supposed to support */
-        assert(mask <= 0xFFFFFFU);
+        assert(TPM2_PCR_MASK_VALID(mask));
 
         *ret = (TPML_PCR_SELECTION) {
                 .count = 1,

src/shared/tpm2-util.h

@@ -11,6 +11,18 @@ typedef enum TPM2Flags {
         TPM2_FLAGS_USE_PIN = 1 << 0,
 } TPM2Flags;
 
+
+/* As per https://trustedcomputinggroup.org/wp-content/uploads/TCG_PCClient_PFP_r1p05_v23_pub.pdf a
+ * TPM2 on a Client PC must have at least 24 PCRs. This hardcodes our expectation of 24. */
+#define TPM2_PCRS_MAX 24U
+#define TPM2_PCRS_MASK ((UINT32_C(1) << TPM2_PCRS_MAX) - 1)
+static inline bool TPM2_PCR_VALID(unsigned pcr) {
+        return pcr < TPM2_PCRS_MAX;
+}
+static inline bool TPM2_PCR_MASK_VALID(uint32_t pcr_mask) {
+        return pcr_mask <= TPM2_PCRS_MASK;
+}
+
 #if HAVE_TPM2
 
 #include <tss2/tss2_esys.h>
@@ -108,12 +120,6 @@ int tpm2_parse_pcr_json_array(JsonVariant *v, uint32_t *ret);
 int tpm2_make_luks2_json(int keyslot, uint32_t hash_pcr_mask, uint16_t pcr_bank, const void *pubkey, size_t pubkey_size, uint32_t pubkey_pcr_mask, uint16_t primary_alg, const void *blob, size_t blob_size, const void *policy_hash, size_t policy_hash_size, const void *salt, size_t salt_size, TPM2Flags flags, JsonVariant **ret);
 int tpm2_parse_luks2_json(JsonVariant *v, int *ret_keyslot, uint32_t *ret_hash_pcr_mask, uint16_t *ret_pcr_bank, void **ret_pubkey, size_t *ret_pubkey_size, uint32_t *ret_pubkey_pcr_mask, uint16_t *ret_primary_alg, void **ret_blob, size_t *ret_blob_size, void **ret_policy_hash, size_t *ret_policy_hash_size, void **ret_salt, size_t *ret_salt_size, TPM2Flags *ret_flags);
 
-#define TPM2_PCRS_MAX 24U
-
-static inline bool TPM2_PCR_MASK_VALID(uint64_t pcr_mask) {
-        return pcr_mask < (UINT64_C(1) << TPM2_PCRS_MAX); /* Support 24 PCR banks */
-}
-
 /* Default to PCR 7 only */
 #define TPM2_PCR_MASK_DEFAULT (UINT32_C(1) << 7)