# Set it to 0 or a negative value for unlimited execution without warnings.
lua-time-limit 5000
+# By default variables in a Lua script are global, this means that a correct
+# script must declare all the local variables explicitly using the 'local'
+# keyword. Lua beginners are known to violate this rule, polluting the global
+# namespace, or creating scripts that may fail under certain conditions, for
+# this reason by default Redis installs a protection that will raise an error
+# every time a script attempts to access a global variable that was not
+# explicitly declared via global().
+#
+# It's worth to note that normal Redis scripts should never use globals, but
+# we don't entirely disable the possibility because from time to time crazy
+# things in the right hands can be pretty powerful.
+#
+# Globals protection may result into a minor performance hint, so it is
+# possible to disable the feature in production environments using the
+# following configuration directive, or at runtime using CONFIG SET.
+lua-protect-globals yes
+
################################## SLOW LOG ###################################
# The Redis Slow Log is a system to log queries that exceeded a specified
}
} else if (!strcasecmp(argv[0],"lua-time-limit") && argc == 2) {
server.lua_time_limit = strtoll(argv[1],NULL,10);
+ } else if (!strcasecmp(argv[0],"lua-protect-globals") && argc == 2) {
+ if ((server.lua_protect_globals = yesnotoi(argv[1])) == -1) {
+ err = "argument must be 'yes' or 'no'"; goto loaderr;
+ }
} else if (!strcasecmp(argv[0],"slowlog-log-slower-than") &&
argc == 2)
{
} else if (!strcasecmp(c->argv[2]->ptr,"lua-time-limit")) {
if (getLongLongFromObject(o,&ll) == REDIS_ERR || ll < 0) goto badfmt;
server.lua_time_limit = ll;
+ } else if (!strcasecmp(c->argv[2]->ptr,"lua-protect-globals")) {
+ int enable = yesnotoi(o->ptr);
+
+ if (enable == -1) goto badfmt;
+ if (enable == 0 && server.lua_protect_globals == 1) {
+ scriptingDisableGlobalsProtection(server.lua);
+ } else if (enable && server.lua_protect_globals == 0) {
+ scriptingEnableGlobalsProtection(server.lua);
+ }
+ server.lua_protect_globals = enable;
} else if (!strcasecmp(c->argv[2]->ptr,"slowlog-log-slower-than")) {
if (getLongLongFromObject(o,&ll) == REDIS_ERR) goto badfmt;
server.slowlog_log_slower_than = ll;
config_get_bool_field("rdbcompression", server.rdb_compression);
config_get_bool_field("rdbchecksum", server.rdb_checksum);
config_get_bool_field("activerehashing", server.activerehashing);
+ config_get_bool_field("lua-protect-globals", server.lua_protect_globals);
/* Everything we can't handle with macros follows. */
#endif
}
-void scriptingProtectGlobals(lua_State *lua) {
- char *s[26];
+/* This function installs metamethods in the global table _G that prevent
+ * the creation of globals accidentally.
+ *
+ * It should be the last to be called in the scripting engine initialization
+ * sequence, because it may interact with creation of globals.
+ * Note that the function is designed to be called multiple times if needed
+ * without issues, because it is possible to enabled/disable globals protection
+ * at runtime with CONFIG SET. */
+void scriptingEnableGlobalsProtection(lua_State *lua) {
+ char *s[32];
sds code = sdsempty();
- int j;
+ int j = 0;
- /* strict.lua from: http://metalua.luaforge.net/src/lib/strict.lua.html */
- s[0]="local mt = getmetatable(_G)\n";
- s[1]="if mt == nil then\n";
- s[2]=" mt = {}\n";
- s[3]=" setmetatable(_G, mt)\n";
- s[4]="end\n";
- s[5]="__STRICT = true\n";
- s[6]="mt.__declared = {}\n";
- s[7]="mt.__newindex = function (t, n, v)\n";
- s[8]=" if __STRICT and not mt.__declared[n] and debug.getinfo(2) then\n";
- s[9]=" local w = debug.getinfo(2, \"S\").what\n";
- s[10]=" if w ~= \"main\" and w ~= \"C\" then\n";
- s[11]=" error(\"assign to undeclared global var '\"..n..\"'\", 2)\n";
- s[12]=" end\n";
- s[13]=" mt.__declared[n] = true\n";
- s[14]=" end\n";
- s[15]=" rawset(t, n, v)\n";
- s[16]="end\n";
- s[17]="mt.__index = function (t, n)\n";
- s[18]=" if debug.getinfo(2) and not mt.__declared[n] and debug.getinfo(2, \"S\").what ~= \"C\" then\n";
- s[19]=" error(\"global var '\"..n..\"' is not declared\", 2)\n";
- s[20]=" end\n";
- s[21]=" return rawget(t, n)\n";
- s[22]="end\n";
- s[23]="function global(...)\n";
- s[24]=" for _, v in ipairs{...} do mt.__declared[v] = true end\n";
- s[25]="end\n";
-
- for (j = 0; j < 26; j++) code = sdscatlen(code,s[j],strlen(s[j]));
- luaL_loadbuffer(lua,code,sdslen(code),"strict_lua");
+ /* strict.lua from: http://metalua.luaforge.net/src/lib/strict.lua.html.
+ * Modified to be adapted to Redis. */
+ s[j++]="mt = {}\n";
+ s[j++]="setmetatable(_G, mt)\n";
+ s[j++]="mt.declared = {}\n";
+ s[j++]="mt.__newindex = function (t, n, v)\n";
+ s[j++]=" if not mt.declared[n] and debug.getinfo(2) then\n";
+ s[j++]=" local w = debug.getinfo(2, \"S\").what\n";
+ s[j++]=" if w ~= \"main\" and w ~= \"C\" then\n";
+ s[j++]=" error(\"assignment to undeclared global variable '\"..n..\"'\", 2)\n";
+ s[j++]=" end\n";
+ s[j++]=" mt.declared[n] = true\n";
+ s[j++]=" end\n";
+ s[j++]=" rawset(t, n, v)\n";
+ s[j++]="end\n";
+ s[j++]="mt.__index = function (t, n)\n";
+ s[j++]=" if debug.getinfo(2) and not mt.declared[n] and debug.getinfo(2, \"S\").what ~= \"C\" then\n";
+ s[j++]=" error(\"global variable '\"..n..\"' is not declared\", 2)\n";
+ s[j++]=" end\n";
+ s[j++]=" return rawget(t, n)\n";
+ s[j++]="end\n";
+ s[j++]="function global(...)\n";
+ s[j++]=" for _, v in ipairs{...} do mt.declared[v] = true end\n";
+ s[j++]="end\n";
+ s[j++]=NULL;
+
+ for (j = 0; s[j] != NULL; j++) code = sdscatlen(code,s[j],strlen(s[j]));
+ luaL_loadbuffer(lua,code,sdslen(code),"enable_strict_lua");
lua_pcall(lua,0,0,0);
sdsfree(code);
}
+void scriptingDisableGlobalsProtection(lua_State *lua) {
+ char *s = "setmetatable(_G, nil)\n";
+ luaL_loadbuffer(lua,s,strlen(s),"disable_strict_lua");
+ lua_pcall(lua,0,0,0);
+}
+
/* Initialize the scripting environment.
* It is possible to call this function to reset the scripting environment
* assuming that we call scriptingRelease() before.
/* Lua beginners ofter don't use "local", this is likely to introduce
* subtle bugs in their code. To prevent problems we protect accesses
* to global variables. */
- scriptingProtectGlobals(lua);
+ if (server.lua_protect_globals)
+ scriptingEnableGlobalsProtection(lua);
server.lua = lua;
}
projects / redis.git / commitdiff
