PROV: Have our PEM->DER decoder only recognise our PEM names

This is to avoid creating confusion where other PEM decoder
implementations may know better what PEM names that are unknown to us
actually mean.

Fixes #15929

Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15930)

diff --git a/providers/implementations/encode_decode/decode_pem2der.c b/providers/implementations/encode_decode/decode_pem2der.c
index 16f33223547d9ae1fb17d7d9ad4fdb994009d3fa..5db3689f30de8b5d65c6b9ea0591235432b6cdbf 100644 (file)
--- a/providers/implementations/encode_decode/decode_pem2der.c
+++ b/providers/implementations/encode_decode/decode_pem2der.c
@@ -92,35 +92,49 @@ static int pem2der_decode(void *vctx, OSSL_CORE_BIO *cin, int selection,
                           OSSL_CALLBACK *data_cb, void *data_cbarg,
                           OSSL_PASSPHRASE_CALLBACK *pw_cb, void *pw_cbarg)
 {
-    /* Strings to peel off the pem name */
-    static struct peelablee_pem_name_endings_st {
-        const char *ending;
+    /*
+     * PEM names we recognise.  Other PEM names should be recognised by
+     * other decoder implementations.
+     */
+    static struct pem_name_map_st {
+        const char *pem_name;
+        int object_type;
+        const char *data_type;
         const char *data_structure;
-    } peelable_pem_name_endings[] = {
-        /*
-         * These entries should be in longest to shortest order to avoid
-         * mixups.
-         */
-        { "ENCRYPTED PRIVATE KEY", "EncryptedPrivateKeyInfo" },
-        { "PRIVATE KEY", "PrivateKeyInfo" },
-        { "PUBLIC KEY", "SubjectPublicKeyInfo" },
-        { "PARAMETERS", NULL }
+    } pem_name_map[] = {
+        /* PKCS#8 and SubjectPublicKeyInfo */
+        { PEM_STRING_PKCS8, OSSL_OBJECT_PKEY, NULL, "EncryptedPrivateKeyInfo" },
+        { PEM_STRING_PKCS8INF, OSSL_OBJECT_PKEY, NULL, "PrivateKeyInfo" },
+        { PEM_STRING_PUBLIC, OSSL_OBJECT_PKEY, NULL, "SubjectPublicKeyInfo" },
+
+        /* Our set of type specific PEM types */
+        { PEM_STRING_DHPARAMS, OSSL_OBJECT_PKEY, "DH", "type-specific" },
+        { PEM_STRING_DHXPARAMS, OSSL_OBJECT_PKEY, "X9.42 DH", "type-specific" },
+        { PEM_STRING_DSA, OSSL_OBJECT_PKEY, "DSA", "type-specific" },
+        { PEM_STRING_DSA_PUBLIC, OSSL_OBJECT_PKEY, "DSA", "type-specific" },
+        { PEM_STRING_DSAPARAMS, OSSL_OBJECT_PKEY, "DSA", "type-specific" },
+        { PEM_STRING_ECPRIVATEKEY, OSSL_OBJECT_PKEY, "EC", "type-specific" },
+        { PEM_STRING_ECPARAMETERS, OSSL_OBJECT_PKEY, "EC", "type-specific" },
+        { PEM_STRING_RSA, OSSL_OBJECT_PKEY, "RSA", "type-specific" },
+        { PEM_STRING_RSA_PUBLIC, OSSL_OBJECT_PKEY, "RSA", "type-specific" },
 
         /*
-         * Libcrypto currently only supports decoding keys with provider side
-         * decoders, so we don't try to peel any other PEM name.  That's an
-         * exercise for when libcrypto starts to treat other types of objects
-         * via providers.
+         * A few others that there is at least have an object type for, even
+         * though there is no provider interface to handle such objects, yet.
+         * However, this is beneficial for the OSSL_STORE result handler.
          */
+        { PEM_STRING_X509, OSSL_OBJECT_CERT, NULL, NULL },
+        { PEM_STRING_X509_TRUSTED, OSSL_OBJECT_CERT, NULL, NULL },
+        { PEM_STRING_X509_OLD, OSSL_OBJECT_CERT, NULL, NULL },
+        { PEM_STRING_X509_CRL, OSSL_OBJECT_CRL, NULL, NULL }
     };
     struct pem2der_ctx_st *ctx = vctx;
     char *pem_name = NULL, *pem_header = NULL;
-    size_t pem_name_len, i;
+    size_t i;
     unsigned char *der = NULL;
     long der_len = 0;
     int ok = 0;
     int objtype = OSSL_OBJECT_UNKNOWN;
-    const char *data_structure = NULL;
 
     ok = read_pem(ctx->provctx, cin, &pem_name, &pem_header,
                   &der, &der_len) > 0;
@@ -153,71 +167,27 @@ static int pem2der_decode(void *vctx, OSSL_CORE_BIO *cin, int selection,
      */
     ok = 1;
 
-    /*
-     * Peal off certain strings from the end of |pem_name|, as they serve
-     * no further purpose.
-     */
-    for (i = 0, pem_name_len = strlen(pem_name);
-         i < OSSL_NELEM(peelable_pem_name_endings);
-         i++) {
-        size_t peel_len = strlen(peelable_pem_name_endings[i].ending);
-        size_t pem_name_offset;
-
-        if (peel_len <= pem_name_len) {
-            pem_name_offset = pem_name_len - peel_len;
-            if (strcmp(pem_name + pem_name_offset,
-                       peelable_pem_name_endings[i].ending) == 0) {
-
-                do {
-                    pem_name[pem_name_offset] = '\0';
-                } while (pem_name_offset > 0
-                         && pem_name[--pem_name_offset] == ' ');
-
-                if (pem_name[0] == '\0') {
-                    OPENSSL_free(pem_name);
-                    pem_name = NULL;
-                }
-                /* All of these peelable endings are for EVP_PKEYs */
-                objtype = OSSL_OBJECT_PKEY;
-                if (pem_name == NULL) {
-                    data_structure = peelable_pem_name_endings[i].data_structure;
-                    if (data_structure == NULL)
-                        goto end;
-                } else {
-                    /*
-                     * If there is an algorithm name prefix then it is a
-                     * type-specific data structure
-                     */
-                    data_structure = "type-specific";
-                }
-                break;
-            }
-        }
-    }
-
-    /* If we don't know the object type yet check if it's one we know about */
-    if (objtype == OSSL_OBJECT_UNKNOWN) {
-        if (strcmp(pem_name, PEM_STRING_X509) == 0
-                || strcmp(pem_name, PEM_STRING_X509_TRUSTED) == 0
-                || strcmp(pem_name, PEM_STRING_X509_OLD) == 0)
-            objtype = OSSL_OBJECT_CERT;
-        else if (strcmp(pem_name, PEM_STRING_X509_CRL) == 0)
-            objtype = OSSL_OBJECT_CRL;
-    }
+    /* Have a look to see if we recognise anything */
+    for (i = 0; i < OSSL_NELEM(pem_name_map); i++)
+        if (strcmp(pem_name, pem_name_map[i].pem_name) == 0)
+            break;
 
-    {
+    if (i < OSSL_NELEM(pem_name_map)) {
         OSSL_PARAM params[5], *p = params;
+        /* We expect these to be read only so casting away the const is ok */
+        char *data_type = (char *)pem_name_map[i].data_type;
+        char *data_structure = (char *)pem_name_map[i].data_structure;
 
-        if (pem_name != NULL)
+        if (data_type != NULL)
             *p++ =
                 OSSL_PARAM_construct_utf8_string(OSSL_OBJECT_PARAM_DATA_TYPE,
-                                                 pem_name, 0);
+                                                 data_type, 0);
 
         /* We expect this to be read only so casting away the const is ok */
         if (data_structure != NULL)
             *p++ =
                 OSSL_PARAM_construct_utf8_string(OSSL_OBJECT_PARAM_DATA_STRUCTURE,
-                                                 (char *)data_structure, 0);
+                                                 data_structure, 0);
         *p++ =
             OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_DATA,
                                               der, der_len);