os_stub/cryptlib_mbedtls: x509: Fixup setting the CSR constraints

We were incorrectly not actually copying the OIDs from the existing
cert. This ensures that we do apply the OIDs

Fixes: 6f798df "os_stub: cryptlib: CSR: Allow copying attributes from an existing cert"
Signed-off-by: Alistair Francis <[email protected]>

Author: alistair23

os_stub/cryptlib_mbedtls/pk/x509.c

@@ -1951,15 +1951,15 @@ bool libspdm_gen_x509_csr(size_t hash_nid, size_t asym_nid,
     mbedtls_x509write_csr req;
     mbedtls_md_type_t md_alg;
     mbedtls_asn1_sequence extns;
-    mbedtls_asn1_sequence *next;
+    mbedtls_asn1_sequence *next_oid;
     mbedtls_x509_buf buf;
     mbedtls_x509_crt *cert;
     mbedtls_pk_context key;
 
     uint8_t pubkey_buffer[LIBSPDM_MAX_PUBKEY_DER_BUFFER_SIZE];
     uint8_t *pubkey_der_data;
     size_t pubkey_der_len;
-    size_t tag_len;
+    size_t oid_tag_len;
 
     /*basic_constraints: CA: false */
     #define BASIC_CONSTRAINTS_STRING_FALSE {0x30, 0x00}
@@ -1973,7 +1973,7 @@ bool libspdm_gen_x509_csr(size_t hash_nid, size_t asym_nid,
     mbedtls_x509write_csr_init(&req);
     mbedtls_pk_init(&key);
     csr_buffer_size = *csr_len;
-    next = NULL;
+    next_oid = NULL;
 
     ret = 1;
     switch (asym_nid)
@@ -2073,55 +2073,55 @@ bool libspdm_gen_x509_csr(size_t hash_nid, size_t asym_nid,
     /* Set key */
     mbedtls_x509write_csr_set_key(&req, &key);
 
+    /*set basicConstraints*/
+    if (mbedtls_x509write_csr_set_extension(&req, MBEDTLS_OID_BASIC_CONSTRAINTS,
+                                            MBEDTLS_OID_SIZE(MBEDTLS_OID_BASIC_CONSTRAINTS),
+                                            is_ca ? basic_constraints_true : basic_constraints_false,
+                                            is_ca ?
+                                            sizeof(basic_constraints_true) :
+                                            sizeof(basic_constraints_false)
+                                            ) != 0) {
+        ret = 1;
+        LIBSPDM_DEBUG((LIBSPDM_DEBUG_INFO,
+                       "mbedtls_x509write_csr_set_extension set basicConstraints failed \n"));
+        goto free_all;
+    }
+
     if (base_cert != NULL) {
         cert = base_cert;
         buf = cert->v3_ext;
         if (mbedtls_asn1_get_sequence_of(&buf.p, buf.p + buf.len, &extns,
                                          MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) {
             ret = 1;
             LIBSPDM_DEBUG((LIBSPDM_DEBUG_INFO,
-                           "mbedtls_x509write_csr_set_extension unable to get tag\n"));
+                           "mbedtls_x509write_csr_set_extension unable to get sequence\n"));
             goto free_all;
         }
 
-        next = &extns;
+        next_oid = &extns;
     }
 
-    while (next) {
-        if (mbedtls_asn1_get_tag(&(next->buf.p), next->buf.p + next->buf.len, &tag_len,
-                                 MBEDTLS_ASN1_OID)) {
+    while (next_oid) {
+        if (mbedtls_asn1_get_tag(&(next_oid->buf.p), next_oid->buf.p + next_oid->buf.len,
+                                 &oid_tag_len, MBEDTLS_ASN1_OID)) {
             ret = 1;
             LIBSPDM_DEBUG((LIBSPDM_DEBUG_INFO,
-                           "mbedtls_x509write_csr_set_extension unable to get tag\n"));
+                           "mbedtls_x509write_csr_set_extension unable to get OID tag\n"));
             goto free_all;
         }
 
-        if (mbedtls_x509write_csr_set_extension(&req, MBEDTLS_OID_BASIC_CONSTRAINTS,
-                                                MBEDTLS_OID_SIZE(MBEDTLS_OID_BASIC_CONSTRAINTS),
-                                                next->buf.p,
-                                                tag_len
+        if (mbedtls_x509write_csr_set_extension(&req, next_oid->buf.p,
+                                                oid_tag_len,
+                                                next_oid->buf.p + oid_tag_len,
+                                                next_oid->buf.len - oid_tag_len
                                                 ) != 0) {
             ret = 1;
             LIBSPDM_DEBUG((LIBSPDM_DEBUG_INFO,
                            "mbedtls_x509write_csr_set_extension set custom OID failed \n"));
             goto free_all;
         }
 
-        next = next->next;
-    }
-
-    /*set basicConstraints*/
-    if (mbedtls_x509write_csr_set_extension(&req, MBEDTLS_OID_BASIC_CONSTRAINTS,
-                                            MBEDTLS_OID_SIZE(MBEDTLS_OID_BASIC_CONSTRAINTS),
-                                            is_ca ? basic_constraints_true : basic_constraints_false,
-                                            is_ca ?
-                                            sizeof(basic_constraints_true) :
-                                            sizeof(basic_constraints_false)
-                                            ) != 0) {
-        ret = 1;
-        LIBSPDM_DEBUG((LIBSPDM_DEBUG_INFO,
-                       "mbedtls_x509write_csr_set_extension set basicConstraints failed \n"));
-        goto free_all;
+        next_oid = next_oid->next;
     }
 
     /*csr data is written at the end of the buffer*/