boot: Fix ASN.1 for mbedtls >= 3.1

In Mbed TLS 3.1, the private fields in the ASN.1 structure were made private.
This breaks code that accesses these private macros.

Fix this by changing the ASN.1 specific code to use a new field accessor
`ASN1_CONTEXT_MEMBER` that will be conditionally defined based on the version of
Mbed TLS that is present.

Signed-off-by: David Brown <david.brown@linaro.org>

Author: d3zd3z

boot/bootutil/include/bootutil/crypto/common.h

@@ -17,4 +17,13 @@
 #define MBEDTLS_CONTEXT_MEMBER(X) X
 #endif
 
+/* Newer versions of Mbed TLS have removed the private accessor requirement for
+ * the ASN1 fields.
+ */
+#if (MBEDTLS_VERSION_NUMBER >= 0x03000000) && (MBEDTLS_VERSION_NUMBER < 0x03010000)
+#define ASN1_CONTEXT_MEMBER(X) MBEDTLS_PRIVATE(X)
+#else
+#define ASN1_CONTEXT_MEMBER(X) X
+#endif
+
 #endif /* __BOOTUTIL_CRYPTO_COMMON_H__ */

boot/bootutil/include/bootutil/crypto/ecdsa.h

@@ -102,13 +102,13 @@ static int bootutil_import_key(uint8_t **cp, uint8_t *end)
         return -2;
     }
     /* id-ecPublicKey (RFC5480) */
-    if (alg.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
-        memcmp(alg.MBEDTLS_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
+    if (alg.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
+        memcmp(alg.ASN1_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
         return -3;
     }
     /* namedCurve (RFC5480) */
-    if (param.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_secp256r1_oid) - 1 ||
-        memcmp(param.MBEDTLS_CONTEXT_MEMBER(p), ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
+    if (param.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_secp256r1_oid) - 1 ||
+        memcmp(param.ASN1_CONTEXT_MEMBER(p), ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
         return -4;
     }
     /* ECPoint (RFC5480) */
@@ -512,12 +512,12 @@ static int bootutil_parse_eckey(bootutil_ecdsa_context *ctx, uint8_t **p, uint8_
     if (mbedtls_asn1_get_alg(p, end, &alg, &param)) {
         return -2;
     }
-    if (alg.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
-      memcmp(alg.MBEDTLS_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
+    if (alg.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
+      memcmp(alg.ASN1_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
         return -3;
     }
-    if (param.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_secp256r1_oid) - 1||
-      memcmp(param.MBEDTLS_CONTEXT_MEMBER(p), ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
+    if (param.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_secp256r1_oid) - 1||
+      memcmp(param.ASN1_CONTEXT_MEMBER(p), ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
         return -4;
     }
 

boot/bootutil/src/encrypted.c

@@ -126,12 +126,12 @@ parse_ec256_enckey(uint8_t **p, uint8_t *end, uint8_t *private_key)
         return -5;
     }
 
-    if (alg.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
-        memcmp(alg.MBEDTLS_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
+    if (alg.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
+        memcmp(alg.ASN1_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
         return -6;
     }
-    if (param.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_secp256r1_oid) - 1 ||
-        memcmp(param.MBEDTLS_CONTEXT_MEMBER(p), ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
+    if (param.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_secp256r1_oid) - 1 ||
+        memcmp(param.ASN1_CONTEXT_MEMBER(p), ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
         return -7;
     }
 
@@ -203,8 +203,8 @@ parse_x25519_enckey(uint8_t **p, uint8_t *end, uint8_t *private_key)
         return -4;
     }
 
-    if (alg.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
-        memcmp(alg.MBEDTLS_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
+    if (alg.ASN1_CONTEXT_MEMBER(len) != sizeof(ec_pubkey_oid) - 1 ||
+        memcmp(alg.ASN1_CONTEXT_MEMBER(p), ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
         return -5;
     }
 

boot/bootutil/src/image_ed25519.c

@@ -45,8 +45,8 @@ bootutil_import_key(uint8_t **cp, uint8_t *end)
         return -2;
     }
 
-    if (alg.MBEDTLS_CONTEXT_MEMBER(len) != sizeof(ed25519_pubkey_oid) - 1 ||
-        memcmp(alg.MBEDTLS_CONTEXT_MEMBER(p), ed25519_pubkey_oid, sizeof(ed25519_pubkey_oid) - 1)) {
+    if (alg.ASN1_CONTEXT_MEMBER(len) != sizeof(ed25519_pubkey_oid) - 1 ||
+        memcmp(alg.ASN1_CONTEXT_MEMBER(p), ed25519_pubkey_oid, sizeof(ed25519_pubkey_oid) - 1)) {
         return -3;
     }