md: Implement one-shot md5

Which can be used for non-cryptographic purposes
even in FIPS mode.

Signed-off-by: Pavol Žáčik <pzacik@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/wrapper.h

@@ -75,6 +75,7 @@ MD5CTX md5_init(void);
 void md5_ctx_free(MD5CTX);
 int md5_update(MD5CTX c, const void *data, size_t len);
 int md5_final(unsigned char *md, MD5CTX c);
+int md5(const unsigned char *digest, size_t len, unsigned char *hash);
 
 SHACTX sha1_init(void);
 void sha1_ctx_free(SHACTX);

src/md_crypto.c

@@ -322,3 +322,52 @@ md5_final(unsigned char *md, MD5CTX c)
     }
     return SSH_OK;
 }
+
+/**
+* @ brief One-shot MD5. Not intended for use in security-relevant contexts.
+*/
+int
+md5(const unsigned char *digest, size_t len, unsigned char *hash)
+{
+    int rc, ret = SSH_ERROR;
+    unsigned int mdlen = 0;
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+    EVP_MD *md5 = NULL;
+#endif
+    MD5CTX c = EVP_MD_CTX_new();
+    if (c == NULL) {
+        goto out;
+    }
+
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+    md5 = EVP_MD_fetch(NULL, "MD5", "provider=default,-fips");
+    if (md5 == NULL) {
+        goto out;
+    }
+    rc = EVP_DigestInit(c, md5);
+#else
+    rc = EVP_DigestInit_ex(c, EVP_md5(), NULL);
+#endif
+    if (rc == 0) {
+        goto out;
+    }
+
+    rc = EVP_DigestUpdate(c, digest, len);
+    if (rc != 1) {
+        goto out;
+    }
+
+    rc = EVP_DigestFinal(c, hash, &mdlen);
+    if (rc != 1) {
+        goto out;
+    }
+
+    ret = SSH_OK;
+
+out:
+    EVP_MD_CTX_free(c);
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+    EVP_MD_free(md5);
+#endif
+    return ret;
+}

src/md_gcrypt.c

@@ -244,3 +244,9 @@ md5_final(unsigned char *md, MD5CTX c)
     gcry_md_close(c);
     return SSH_OK;
 }
+
+int md5(const unsigned char *digest, size_t len, unsigned char *hash)
+{
+    gcry_md_hash_buffer(GCRY_MD_MD5, hash, digest, len);
+    return SSH_OK;
+}

src/md_mbedcrypto.c

@@ -405,3 +405,51 @@ md5_final(unsigned char *md, MD5CTX c)
     }
     return SSH_OK;
 }
+
+int md5(const unsigned char *digest, size_t len, unsigned char *hash)
+{
+    MD5CTX ctx = NULL;
+    int rc;
+    const mbedtls_md_info_t *md_info =
+        mbedtls_md_info_from_type(MBEDTLS_MD_MD5);
+    if (md_info == NULL) {
+        return SSH_ERROR;
+    }
+
+    ctx = malloc(sizeof(mbedtls_md_context_t));
+    if (ctx == NULL) {
+        return SSH_ERROR;
+    }
+
+    mbedtls_md_init(ctx);
+
+    rc = mbedtls_md_setup(ctx, md_info, 0);
+    if (rc != 0) {
+        mbedtls_md_free(ctx);
+        SAFE_FREE(ctx);
+        return SSH_ERROR;
+    }
+
+    rc = mbedtls_md_starts(ctx);
+    if (rc != 0) {
+        mbedtls_md_free(ctx);
+        SAFE_FREE(ctx);
+        return SSH_ERROR;
+    }
+
+    rc = mbedtls_md_update(ctx, digest, len);
+    if (rc != 0) {
+        mbedtls_md_free(ctx);
+        SAFE_FREE(ctx);
+        return SSH_ERROR;
+    }
+
+    rc = mbedtls_md_finish(ctx, hash);
+    mbedtls_md_free(ctx);
+    SAFE_FREE(ctx);
+    if (rc != 0) {
+        return SSH_ERROR;
+    }
+
+    return SSH_OK;
+}