Added support for SCRAM-SHA-1, SCRAM-SHA-256 and SCRAM-SHA-512

docs/help/in/network.in

@@ -36,8 +36,8 @@
     -cmdmax:         Specifies the maximum number of commands to perform before
                      starting the internal flood protection.
     -sasl_mechanism  Specifies the mechanism to use for the SASL authentication.
-                     At the moment irssi only supports the 'plain' and the
-                     'external' mechanisms.
+                     Irssi supports: PLAIN, EXTERNAL, SCRAM-SHA-1, SCRAM-SHA-256
+                     and SCRAM-SHA-512
                      Use '' to disable the authentication.
     -sasl_username   Specifies the username to use during the SASL authentication.
     -sasl_password   Specifies the password to use during the SASL authentication.

src/irc/core/irc-core.c

@@ -77,6 +77,10 @@ static void destroy_server_connect(SERVER_CONNECT_REC *conn)
 	g_free_not_null(ircconn->alternate_nick);
 	g_free_not_null(ircconn->sasl_username);
 	g_free_not_null(ircconn->sasl_password);
+
+	if (ircconn->scram_session != NULL) {
+		scram_session_free(ircconn->scram_session);
+	}
 }
 
 void irc_core_init(void)

src/irc/core/irc-servers-setup.c

@@ -128,11 +128,27 @@ static void sig_server_setup_fill_chatnet(IRC_SERVER_CONNECT_REC *conn,
 				conn->sasl_password = g_strdup(ircnet->sasl_password);
 			} else
 				g_warning("The fields sasl_username and sasl_password are either missing or empty");
-		}
-		else if (!g_ascii_strcasecmp(ircnet->sasl_mechanism, "external")) {
+		} else if (!g_ascii_strcasecmp(ircnet->sasl_mechanism, "SCRAM-SHA-1") ||
+		           !g_ascii_strcasecmp(ircnet->sasl_mechanism, "SCRAM-SHA-256") ||
+		           !g_ascii_strcasecmp(ircnet->sasl_mechanism, "SCRAM-SHA-512")) {
+			/* The SCRAM-SHA-* methods need both the username and the password */
+			if (ircnet->sasl_username != NULL && *ircnet->sasl_username &&
+			    ircnet->sasl_password != NULL && *ircnet->sasl_password) {
+				if (!g_ascii_strcasecmp(ircnet->sasl_mechanism, "SCRAM-SHA-1"))
+					conn->sasl_mechanism = SASL_MECHANISM_SCRAM_SHA_1;
+				if (!g_ascii_strcasecmp(ircnet->sasl_mechanism, "SCRAM-SHA-256"))
+					conn->sasl_mechanism = SASL_MECHANISM_SCRAM_SHA_256;
+				if (!g_ascii_strcasecmp(ircnet->sasl_mechanism, "SCRAM-SHA-512"))
+					conn->sasl_mechanism = SASL_MECHANISM_SCRAM_SHA_512;
+
+				conn->sasl_username = g_strdup(ircnet->sasl_username);
+				conn->sasl_password = g_strdup(ircnet->sasl_password);
+			} else
+				g_warning("The fields sasl_username and sasl_password are either "
+				          "missing or empty");
+		} else if (!g_ascii_strcasecmp(ircnet->sasl_mechanism, "external")) {
 			conn->sasl_mechanism = SASL_MECHANISM_EXTERNAL;
-		}
-		else
+		} else
 			g_warning("Unsupported SASL mechanism \"%s\" selected", ircnet->sasl_mechanism);
 	}
 }

src/irc/core/irc-servers.h

@@ -4,6 +4,7 @@
 #include <irssi/src/core/chat-protocols.h>
 #include <irssi/src/core/servers.h>
 #include <irssi/src/irc/core/modes.h>
+#include <irssi/src/irc/core/scram.h>
 
 /*
  * 63 is the maximum hostname length defined by the protocol.  10 is a common
@@ -54,6 +55,7 @@ struct _IRC_SERVER_CONNECT_REC {
 	int sasl_mechanism;
 	char *sasl_username;
 	char *sasl_password;
+	SCRAM_SESSION_REC *scram_session;
 
 	int max_cmds_at_once;
 	int cmd_queue_speed;

src/irc/core/meson.build

@@ -28,6 +28,7 @@ libirc_core_a = static_library('irc_core',
     'modes.c',
     'netsplit.c',
     'sasl.c',
+    'scram.c',
     'servers-idle.c',
     'servers-redirect.c',
   ),
@@ -70,6 +71,7 @@ install_headers(
     'module.h',
     'netsplit.h',
     'sasl.h',
+    'scram.h',
     'servers-idle.h',
     'servers-redirect.h',
   ),

src/irc/core/sasl.c

@@ -80,6 +80,18 @@ static void sasl_start(IRC_SERVER_REC *server, const char *data, const char *fro
 		case SASL_MECHANISM_EXTERNAL:
 			irc_send_cmd_now(server, "AUTHENTICATE EXTERNAL");
 			break;
+
+	        case SASL_MECHANISM_SCRAM_SHA_1:
+		        irc_send_cmd_now(server, "AUTHENTICATE SCRAM-SHA-1");
+		        break;
+
+	        case SASL_MECHANISM_SCRAM_SHA_256:
+		        irc_send_cmd_now(server, "AUTHENTICATE SCRAM-SHA-256");
+		        break;
+
+	        case SASL_MECHANISM_SCRAM_SHA_512:
+		        irc_send_cmd_now(server, "AUTHENTICATE SCRAM-SHA-512");
+		        break;
 	}
 	server->sasl_timeout = g_timeout_add(SASL_TIMEOUT, (GSourceFunc) sasl_timeout, server);
 }
@@ -223,6 +235,54 @@ void sasl_send_response(IRC_SERVER_REC *server, GString *response)
 	g_free(enc);
 }
 
+/*
+ * Sends AUTHENTICATE messages to log in via SCRAM.
+ */
+static void scram_authenticate(IRC_SERVER_REC *server, const char *data, const char *digest)
+{
+	char *output;
+	int ret;
+	size_t output_len;
+	IRC_SERVER_CONNECT_REC *conn = server->connrec;
+
+	if (conn->scram_session == NULL) {
+		conn->scram_session =
+		    scram_session_create(digest, conn->sasl_username, conn->sasl_password);
+
+		if (conn->scram_session == NULL) {
+			g_error("Could not create SCRAM session with digest %s", digest);
+			irc_send_cmd_now(server, "AUTHENTICATE *");
+			return;
+		}
+	}
+
+	ret = scram_process(conn->scram_session, data, &output, &output_len);
+
+	if (ret == SCRAM_IN_PROGRESS) {
+		// Authentication is still in progress
+		GString *resp = g_string_new(output);
+		sasl_send_response(server, resp);
+		g_string_free(resp, TRUE);
+		g_free(output);
+	} else if (ret == SCRAM_SUCCESS) {
+		// Authentication succeeded
+		irc_send_cmd_now(server, "AUTHENTICATE +");
+		scram_session_free(conn->scram_session);
+		conn->scram_session = NULL;
+	} else if (ret == SCRAM_ERROR) {
+		// Authentication failed
+		irc_send_cmd_now(server, "AUTHENTICATE *");
+
+		if (conn->scram_session->error != NULL) {
+			g_warning("SASL SCRAM authentication failed: %s",
+			          conn->scram_session->error);
+		}
+
+		scram_session_free(conn->scram_session);
+		conn->scram_session = NULL;
+	}
+}
+
 /*
  * Called when the incoming SASL request is completely received.
  */
@@ -258,6 +318,18 @@ static void sasl_step_complete(IRC_SERVER_REC *server, GString *data)
 			/* Empty response */
 			sasl_send_response(server, NULL);
 			break;
+
+	        case SASL_MECHANISM_SCRAM_SHA_1:
+		        scram_authenticate(server, data->str, "SHA1");
+		        break;
+
+	        case SASL_MECHANISM_SCRAM_SHA_256:
+		        scram_authenticate(server, data->str, "SHA256");
+		        break;
+
+	        case SASL_MECHANISM_SCRAM_SHA_512:
+		        scram_authenticate(server, data->str, "SHA512");
+		        break;
 	}
 }
 

src/irc/core/sasl.h

@@ -25,6 +25,9 @@ enum {
 	SASL_MECHANISM_NONE = 0,
 	SASL_MECHANISM_PLAIN,
 	SASL_MECHANISM_EXTERNAL,
+	SASL_MECHANISM_SCRAM_SHA_1,
+	SASL_MECHANISM_SCRAM_SHA_256,
+	SASL_MECHANISM_SCRAM_SHA_512,
 	SASL_MECHANISM_MAX
 };
 

src/irc/core/scram.c

@@ -0,0 +1,303 @@
+/*
+ scram.c : irssi
+
+    Copyright (C) 2023 Patrick Okraku
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "module.h"
+#include <irssi/src/irc/core/scram.h>
+#include <openssl/hmac.h>
+#include <openssl/rand.h>
+
+#define NONCE_LENGTH 18
+#define CLIENT_KEY "Client Key"
+#define SERVER_KEY "Server Key"
+
+// EVP_MD_CTX_create() and EVP_MD_CTX_destroy() were renamed in OpenSSL 1.1.0
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#define EVP_MD_CTX_new(ctx) EVP_MD_CTX_create(ctx)
+#define EVP_MD_CTX_free(ctx) EVP_MD_CTX_destroy(ctx)
+#endif
+
+SCRAM_SESSION_REC *scram_session_create(const char *digest, const char *username,
+                                        const char *password)
+{
+	SCRAM_SESSION_REC *session;
+	const EVP_MD *md;
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+	OpenSSL_add_all_algorithms();
+#endif
+	md = EVP_get_digestbyname(digest);
+
+	if (md == NULL) {
+		// Unknown message digest
+		return NULL;
+	}
+
+	session = g_new0(SCRAM_SESSION_REC, 1);
+	session->digest = md;
+	session->digest_size = EVP_MD_size(md);
+	session->username = g_strdup(username);
+	session->password = g_strdup(password);
+	return session;
+}
+
+void scram_session_free(SCRAM_SESSION_REC *session)
+{
+	if (session == NULL) {
+		return;
+	}
+
+	g_free(session->username);
+	g_free(session->password);
+	g_free(session->client_nonce_b64);
+	g_free(session->client_first_message_bare);
+	g_free(session->salted_password);
+	g_free(session->auth_message);
+	g_free(session->error);
+
+	g_free(session);
+}
+
+static int create_nonce(void *buffer, size_t length)
+{
+	return RAND_bytes(buffer, length);
+}
+
+static int create_SHA(SCRAM_SESSION_REC *session, const unsigned char *input, size_t input_len,
+                      unsigned char *output, unsigned int *output_len)
+{
+	EVP_MD_CTX *md_ctx = EVP_MD_CTX_new();
+
+	if (!EVP_DigestInit_ex(md_ctx, session->digest, NULL)) {
+		session->error = g_strdup("Message digest initialization failed");
+		EVP_MD_CTX_free(md_ctx);
+		return SCRAM_ERROR;
+	}
+
+	if (!EVP_DigestUpdate(md_ctx, input, input_len)) {
+		session->error = g_strdup("Message digest update failed");
+		EVP_MD_CTX_free(md_ctx);
+		return SCRAM_ERROR;
+	}
+
+	if (!EVP_DigestFinal_ex(md_ctx, output, output_len)) {
+		session->error = g_strdup("Message digest finalization failed");
+		EVP_MD_CTX_free(md_ctx);
+		return SCRAM_ERROR;
+	}
+
+	EVP_MD_CTX_free(md_ctx);
+	return SCRAM_IN_PROGRESS;
+}
+
+static scram_status process_client_first(SCRAM_SESSION_REC *session, char **output,
+                                         size_t *output_len)
+{
+	char nonce[NONCE_LENGTH];
+
+	if (!create_nonce(nonce, NONCE_LENGTH)) {
+		session->error = g_strdup("Could not create client nonce");
+		return SCRAM_ERROR;
+	}
+
+	session->client_nonce_b64 = g_base64_encode((guchar *) nonce, NONCE_LENGTH);
+	*output = g_strdup_printf("n,,n=%s,r=%s", session->username, session->client_nonce_b64);
+	*output_len = strlen(*output);
+	session->client_first_message_bare = g_strdup(*output + 3);
+	session->step++;
+	return SCRAM_IN_PROGRESS;
+}
+
+static scram_status process_server_first(SCRAM_SESSION_REC *session, const char *data,
+                                         char **output, size_t *output_len)
+{
+	char **params, *client_final_message_without_proof, *salt, *server_nonce_b64,
+	    *client_proof_b64;
+	unsigned char *client_key, stored_key[EVP_MAX_MD_SIZE], *client_signature, *client_proof;
+	unsigned int i, param_count, iteration_count, client_key_len, stored_key_len;
+	gsize salt_len = 0;
+	size_t client_nonce_len;
+
+	params = g_strsplit(data, ",", -1);
+	param_count = g_strv_length(params);
+
+	if (param_count < 3) {
+		session->error = g_strdup_printf("Invalid server-first-message: %s", data);
+		g_strfreev(params);
+		return SCRAM_ERROR;
+	}
+
+	server_nonce_b64 = NULL;
+	salt = NULL;
+	iteration_count = 0;
+
+	for (i = 0; i < param_count; i++) {
+		if (!strncmp(params[i], "r=", 2)) {
+			g_free(server_nonce_b64);
+			server_nonce_b64 = g_strdup(params[i] + 2);
+		} else if (!strncmp(params[i], "s=", 2)) {
+			g_free(salt);
+			salt = g_strdup(params[i] + 2);
+		} else if (!strncmp(params[i], "i=", 2)) {
+			iteration_count = strtoul(params[i] + 2, NULL, 10);
+		}
+	}
+
+	g_strfreev(params);
+
+	if (server_nonce_b64 == NULL || *server_nonce_b64 == '\0' || salt == NULL ||
+	    *salt == '\0' || iteration_count == 0) {
+		session->error = g_strdup_printf("Invalid server-first-message: %s", data);
+		g_free(server_nonce_b64);
+		g_free(salt);
+		return SCRAM_ERROR;
+	}
+
+	client_nonce_len = strlen(session->client_nonce_b64);
+
+	// The server can append his nonce to the client's nonce
+	if (strlen(server_nonce_b64) < client_nonce_len ||
+	    strncmp(server_nonce_b64, session->client_nonce_b64, client_nonce_len)) {
+		session->error = g_strdup_printf("Invalid server nonce: %s", server_nonce_b64);
+		return SCRAM_ERROR;
+	}
+
+	g_base64_decode_inplace((gchar *) salt, &salt_len);
+
+	// SaltedPassword := Hi(Normalize(password), salt, i)
+	session->salted_password = g_malloc(session->digest_size);
+
+	PKCS5_PBKDF2_HMAC(session->password, strlen(session->password), (unsigned char *) salt,
+	                  salt_len, iteration_count, session->digest, session->digest_size,
+	                  session->salted_password);
+
+	// AuthMessage := client-first-message-bare + "," +
+	//                server-first-message + "," +
+	//                client-final-message-without-proof
+	client_final_message_without_proof = g_strdup_printf("c=biws,r=%s", server_nonce_b64);
+
+	session->auth_message = g_strdup_printf("%s,%s,%s", session->client_first_message_bare,
+	                                        data, client_final_message_without_proof);
+
+	// ClientKey := HMAC(SaltedPassword, "Client Key")
+	client_key = g_malloc0(session->digest_size);
+
+	HMAC(session->digest, session->salted_password, session->digest_size,
+	     (unsigned char *) CLIENT_KEY, strlen(CLIENT_KEY), client_key, &client_key_len);
+
+	// StoredKey := H(ClientKey)
+	if (!create_SHA(session, client_key, session->digest_size, stored_key, &stored_key_len)) {
+		g_free(client_final_message_without_proof);
+		g_free(server_nonce_b64);
+		g_free(salt);
+		g_free(client_key);
+		return SCRAM_ERROR;
+	}
+
+	// ClientSignature := HMAC(StoredKey, AuthMessage)
+	client_signature = g_malloc0(session->digest_size);
+	HMAC(session->digest, stored_key, stored_key_len, (unsigned char *) session->auth_message,
+	     strlen((char *) session->auth_message), client_signature, NULL);
+
+	// ClientProof := ClientKey XOR ClientSignature
+	client_proof = g_malloc0(client_key_len);
+
+	for (i = 0; i < client_key_len; i++) {
+		client_proof[i] = client_key[i] ^ client_signature[i];
+	}
+
+	client_proof_b64 = g_base64_encode((guchar *) client_proof, client_key_len);
+
+	*output = g_strdup_printf("%s,p=%s", client_final_message_without_proof, client_proof_b64);
+	*output_len = strlen(*output);
+
+	g_free(server_nonce_b64);
+	g_free(salt);
+	g_free(client_final_message_without_proof);
+	g_free(client_key);
+	g_free(client_signature);
+	g_free(client_proof);
+	g_free(client_proof_b64);
+
+	session->step++;
+	return SCRAM_IN_PROGRESS;
+}
+
+static scram_status process_server_final(SCRAM_SESSION_REC *session, const char *data)
+{
+	char *verifier;
+	unsigned char *server_key, *server_signature;
+	unsigned int server_key_len = 0, server_signature_len = 0;
+	gsize verifier_len = 0;
+
+	if (strlen(data) < 3 || (data[0] != 'v' && data[1] != '=')) {
+		return SCRAM_ERROR;
+	}
+
+	verifier = g_strdup(data + 2);
+	g_base64_decode_inplace(verifier, &verifier_len);
+
+	// ServerKey := HMAC(SaltedPassword, "Server Key")
+	server_key = g_malloc0(session->digest_size);
+	HMAC(session->digest, session->salted_password, session->digest_size,
+	     (unsigned char *) SERVER_KEY, strlen(SERVER_KEY), server_key, &server_key_len);
+
+	// ServerSignature := HMAC(ServerKey, AuthMessage)
+	server_signature = g_malloc0(session->digest_size);
+	HMAC(session->digest, server_key, session->digest_size,
+	     (unsigned char *) session->auth_message, strlen((char *) session->auth_message),
+	     server_signature, &server_signature_len);
+
+	if (verifier_len == server_signature_len &&
+	    memcmp(verifier, server_signature, verifier_len) == 0) {
+		g_free(verifier);
+		g_free(server_key);
+		g_free(server_signature);
+		return SCRAM_SUCCESS;
+	} else {
+		g_free(verifier);
+		g_free(server_key);
+		g_free(server_signature);
+		return SCRAM_ERROR;
+	}
+}
+
+scram_status scram_process(SCRAM_SESSION_REC *session, const char *input, char **output,
+                           size_t *output_len)
+{
+	scram_status status;
+
+	switch (session->step) {
+	case 0:
+		status = process_client_first(session, output, output_len);
+		break;
+	case 1:
+		status = process_server_first(session, input, output, output_len);
+		break;
+	case 2:
+		status = process_server_final(session, input);
+		break;
+	default:
+		*output = NULL;
+		*output_len = 0;
+		status = SCRAM_ERROR;
+		break;
+	}
+
+	return status;
+}

src/irc/core/scram.h

@@ -0,0 +1,27 @@
+#ifndef IRSSI_IRC_CORE_SCRAM_H
+#define IRSSI_IRC_CORE_SCRAM_H
+
+#include <openssl/evp.h>
+
+typedef struct {
+	const EVP_MD *digest;
+	size_t digest_size;
+	char *username;
+	char *password;
+	char *client_nonce_b64;
+	char *client_first_message_bare;
+	unsigned char *salted_password;
+	char *auth_message;
+	char *error;
+	int step;
+} SCRAM_SESSION_REC;
+
+typedef enum { SCRAM_ERROR = 0, SCRAM_IN_PROGRESS, SCRAM_SUCCESS } scram_status;
+
+SCRAM_SESSION_REC *scram_session_create(const char *digset, const char *username,
+                                        const char *password);
+void scram_session_free(SCRAM_SESSION_REC *session);
+scram_status scram_process(SCRAM_SESSION_REC *session, const char *input, char **output,
+                           size_t *output_len);
+
+#endif