PROV: Implement padding mode words in the RSA ASYM_CIPHER implementation

Because the libcrypto code has relinquished control of exact words to
express padding mode choices, we re-implement them in the appropriate
provider implementation.

For the sake of legacy controls, we maintain support for the numeric
form of the padding mode, but leave that support otherwise undeclared.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10947)

1 files changed, 66 insertions, 6 deletions

diff --git a/providers/implementations/asymciphers/rsa_enc.c b/providers/implementations/asymciphers/rsa_enc.c
index 77f807e7ef..c72571d6bb 100644
--- a/providers/implementations/asymciphers/rsa_enc.c
+++ b/providers/implementations/asymciphers/rsa_enc.c
@@ -37,6 +37,16 @@ static OSSL_OP_asym_cipher_gettable_ctx_params_fn rsa_gettable_ctx_params;
 static OSSL_OP_asym_cipher_set_ctx_params_fn rsa_set_ctx_params;
 static OSSL_OP_asym_cipher_settable_ctx_params_fn rsa_settable_ctx_params;
 
+static OSSL_ITEM padding_item[] = {
+    { RSA_PKCS1_PADDING,        "pkcs1"  },
+    { RSA_SSLV23_PADDING,       "sslv23" },
+    { RSA_NO_PADDING,           "none"   },
+    { RSA_PKCS1_OAEP_PADDING,   "oaep"   }, /* Correct spelling first */
+    { RSA_PKCS1_OAEP_PADDING,   "oeap"   },
+    { RSA_X931_PADDING,         "x931"   },
+    { RSA_PKCS1_PSS_PADDING,    "pss"    },
+    { 0,                        NULL     }
+};
 
 /*
  * What's passed as an actual key is defined by the KEYMGMT interface.
@@ -263,8 +273,35 @@ static int rsa_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
         return 0;
 
     p = OSSL_PARAM_locate(params, OSSL_ASYM_CIPHER_PARAM_PAD_MODE);
-    if (p != NULL && !OSSL_PARAM_set_int(p, prsactx->pad_mode))
-        return 0;
+    if (p != NULL)
+        switch (p->data_type) {
+        case OSSL_PARAM_INTEGER: /* Support for legacy pad mode number */
+            if (!OSSL_PARAM_set_int(p, prsactx->pad_mode))
+                return 0;
+            break;
+        case OSSL_PARAM_UTF8_STRING:
+            {
+                int i;
+                const char *word = NULL;
+
+                for (i = 0; padding_item[i].id != 0; i++) {
+                    if (prsactx->pad_mode == (int)padding_item[i].id) {
+                        word = padding_item[i].ptr;
+                        break;
+                    }
+                }
+
+                if (word != NULL) {
+                    if (!OSSL_PARAM_set_utf8_string(p, word))
+                        return 0;
+                } else {
+                    ERR_raise(ERR_LIB_PROV, ERR_R_INTERNAL_ERROR);
+                }
+            }
+            break;
+        default:
+            return 0;
+        }
 
     p = OSSL_PARAM_locate(params, OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST);
     if (p != NULL && !OSSL_PARAM_set_utf8_string(p, prsactx->oaep_md == NULL
@@ -304,7 +341,7 @@ static int rsa_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
 
 static const OSSL_PARAM known_gettable_ctx_params[] = {
     OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST, NULL, 0),
-    OSSL_PARAM_int(OSSL_ASYM_CIPHER_PARAM_PAD_MODE, NULL),
+    OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_PAD_MODE, NULL, 0),
     OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST, NULL, 0),
     OSSL_PARAM_DEFN(OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL, OSSL_PARAM_OCTET_PTR,
                     NULL, 0),
@@ -326,7 +363,6 @@ static int rsa_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
     char mdname[OSSL_MAX_NAME_SIZE];
     char mdprops[OSSL_MAX_PROPQUERY_SIZE] = { '\0' };
     char *str = mdname;
-    int pad_mode;
 
     if (prsactx == NULL || params == NULL)
         return 0;
@@ -353,8 +389,32 @@ static int rsa_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
 
     p = OSSL_PARAM_locate_const(params, OSSL_ASYM_CIPHER_PARAM_PAD_MODE);
     if (p != NULL) {
-        if (!OSSL_PARAM_get_int(p, &pad_mode))
+        int pad_mode = 0;
+
+        switch (p->data_type) {
+        case OSSL_PARAM_INTEGER: /* Support for legacy pad mode number */
+            if (!OSSL_PARAM_get_int(p, &pad_mode))
+                return 0;
+            break;
+        case OSSL_PARAM_UTF8_STRING:
+            {
+                int i;
+
+                if (p->data == NULL)
+                    return 0;
+
+                for (i = 0; padding_item[i].id != 0; i++) {
+                    if (strcmp(p->data, padding_item[i].ptr) == 0) {
+                        pad_mode = padding_item[i].id;
+                        break;
+                    }
+                }
+            }
+            break;
+        default:
             return 0;
+        }
+
         /*
          * PSS padding is for signatures only so is not compatible with
          * asymmetric cipher use.
@@ -426,7 +486,7 @@ static int rsa_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
 
 static const OSSL_PARAM known_settable_ctx_params[] = {
     OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST, NULL, 0),
-    OSSL_PARAM_int(OSSL_ASYM_CIPHER_PARAM_PAD_MODE, NULL),
+    OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_PAD_MODE, NULL, 0),
     OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST, NULL, 0),
     OSSL_PARAM_utf8_string(OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS, NULL, 0),
     OSSL_PARAM_octet_string(OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL, NULL, 0),