server: User password hashing (libsodium Argon2id(3,64MB))

4 files changed, 75 insertions, 17 deletions

diff --git a/command.c b/command.c
index 04e9fe0..51acfb6 100644
--- a/command.c
+++ b/command.c
@@ -50,9 +50,7 @@ static struct cmd_retval cmd_login(struct conn_data *data,const char *tag,const
 			data->userid=-1;
 		}
 	} else {
-		char *pass=db_get_pass(userid);
-		bool success=strcmp(args[1],pass)==0;
-		free(pass);
+		bool success = db_check_pass(userid, args[1]);
 		if(data->userid!=-1){
 			userdata_unregister(data->userid,data->fd);
 			broadcast_online_change(data->userid);
diff --git a/db.c b/db.c
index 4572ea2..413953b 100644
--- a/db.c
+++ b/db.c
@@ -3,6 +3,7 @@
 #include <string.h>
 #include <assert.h>
 #include <sqlite3.h>
+#include <sodium.h>
 #include "db.h"
 #include "schema.sql.h"
 
@@ -10,6 +11,8 @@
 #define SQLITE(func,...) do{if(sqlite3_##func(__VA_ARGS__)!=SQLITE_OK){die_sqlite("sqlite3_" #func);}}while(0)
 
 #define DATABASE_VERSION 1
+#define PASSHASH_OPSLIMIT 3
+#define PASSHASH_MEMLIMIT crypto_pwhash_MEMLIMIT_INTERACTIVE
 
 
 sqlite3 *database=NULL;
@@ -19,6 +22,24 @@ static void die_sqlite(const char *func){
 	die("%s: %s",func,sqlite3_errmsg(database));
 }
 
+struct hashed_password {
+	char str[crypto_pwhash_STRBYTES + 1];
+	int length;  // -1 if hashing failed
+};
+
+static struct hashed_password hash_password(const char *pass) {
+	struct hashed_password result;
+	int ret = crypto_pwhash_str(
+			result.str, pass, strlen(pass),
+			PASSHASH_OPSLIMIT, PASSHASH_MEMLIMIT);
+	if (ret != 0) {
+		result.length = -1;
+	} else {
+		result.length = crypto_pwhash_STRBYTES;
+	}
+	return result;
+}
+
 
 void db_init(void){
 	SQLITE(config,SQLITE_CONFIG_SERIALIZED);
@@ -210,10 +231,13 @@ struct db_room_list db_list_rooms(i64 userid){
 
 
 i64 db_create_user(const char *name,const char *pass){
+	struct hashed_password passhash = hash_password(pass);
+	if (passhash.length == -1) return -1;
+
 	sqlite3_stmt *stmt;
-	SQLITE(prepare_v2,database,"insert into Users (name, pass) values (?, ?)",-1,&stmt,NULL);
+	SQLITE(prepare_v2,database,"insert into Users (name, passhash) values (?, ?)",-1,&stmt,NULL);
 	SQLITE(bind_text,stmt,1,name,-1,SQLITE_STATIC);
-	SQLITE(bind_text,stmt,2,pass,-1,SQLITE_STATIC);
+	SQLITE(bind_text,stmt,2,passhash.str,passhash.length,SQLITE_STATIC);
 	bool success=sqlite3_step(stmt)==SQLITE_DONE;
 	SQLITE(finalize,stmt);
 	if(success){
@@ -223,6 +247,29 @@ i64 db_create_user(const char *name,const char *pass){
 	}
 }
 
+bool db_set_username(i64 userid, const char *name) {
+	sqlite3_stmt *stmt;
+	SQLITE(prepare_v2, database, "update USERS set name = ? where id = ?", -1, &stmt, NULL);
+	SQLITE(bind_text, stmt, 1, name, -1, SQLITE_STATIC);
+	SQLITE(bind_int64, stmt, 2, userid);
+	bool success = sqlite3_step(stmt) == SQLITE_DONE;
+	SQLITE(finalize, stmt);
+	return success;
+}
+
+bool db_set_pass(i64 userid, const char *pass) {
+	struct hashed_password passhash = hash_password(pass);
+	if (passhash.length == -1) return false;
+
+	sqlite3_stmt *stmt;
+	SQLITE(prepare_v2, database, "update USERS set passhash = ? where id = ?", -1, &stmt, NULL);
+	SQLITE(bind_text, stmt, 1, passhash.str, passhash.length, SQLITE_STATIC);
+	SQLITE(bind_int64, stmt, 2, userid);
+	bool success = sqlite3_step(stmt) == SQLITE_DONE;
+	SQLITE(finalize, stmt);
+	return success;
+}
+
 char* db_get_username(i64 userid){
 	sqlite3_stmt *stmt;
 	SQLITE(prepare_v2,database,"select name from Users where id = ?",-1,&stmt,NULL);
@@ -237,18 +284,31 @@ char* db_get_username(i64 userid){
 	return name;
 }
 
-char* db_get_pass(i64 userid){
+bool db_check_pass(i64 userid, const char *pass) {
 	sqlite3_stmt *stmt;
-	SQLITE(prepare_v2,database,"select pass from Users where id = ?",-1,&stmt,NULL);
-	SQLITE(bind_int64,stmt,1,userid);
-	const unsigned char *pass_sq=NULL;
-	if(sqlite3_step(stmt)==SQLITE_ROW){
-		pass_sq=sqlite3_column_text(stmt,0);
+	SQLITE(prepare_v2, database, "select passhash from Users where id = ?", -1, &stmt, NULL);
+	SQLITE(bind_int64, stmt, 1, userid);
+
+	const unsigned char *passhash_sq = NULL;
+	if (sqlite3_step(stmt) == SQLITE_ROW) {
+		passhash_sq = sqlite3_column_text(stmt, 0);
 	}
-	char *pass=NULL;
-	if(pass_sq)pass=strdup((const char*)pass_sq);
-	SQLITE(finalize,stmt);
-	return pass;
+
+	int ret = crypto_pwhash_str_verify((const char*)passhash_sq, pass, strlen(pass));
+	bool success = ret == 0;
+	bool rehash = success &&
+					crypto_pwhash_str_needs_rehash(
+							(const char*)passhash_sq, PASSHASH_OPSLIMIT, PASSHASH_MEMLIMIT);
+
+	SQLITE(finalize, stmt);
+
+	if (rehash) {
+		fprintf(stderr, "Rehashing password for userid=%" PRIi64 "\n", userid);
+		// Ignore whether this succeeds; if it doesn't, we continue using the old hash
+		db_set_pass(userid, pass);
+	}
+
+	return success;
 }
 
 i64 db_find_user(const char *name){
diff --git a/db.h b/db.h
index a56bc70..c27b243 100644
--- a/db.h
+++ b/db.h
@@ -52,7 +52,7 @@ i64 db_create_user(const char *name,const char *pass);
 bool db_set_username(i64 userid,const char *name);
 bool db_set_pass(i64 userid,const char *pass);
 char* db_get_username(i64 userid);
-char* db_get_pass(i64 userid);
+bool db_check_pass(i64 userid,const char *pass);
 bool db_delete_user(i64 userid);
 i64 db_find_user(const char *name);  // -1 if not found
 struct db_strings_list db_user_tokens(i64 userid);
diff --git a/schema.sql b/schema.sql
index 3efe0f1..06baafd 100644
--- a/schema.sql
+++ b/schema.sql
@@ -21,7 +21,7 @@ create table Members (
 create table Users (
 	id integer primary key not null,
 	name text not null,
-	pass text not null
+	passhash text not null
 );
 create unique index users_name_index on Users(name);