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Scripting: globals protection can now be switched on/off.

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This commit is contained in:
antirez
2012-04-13 11:16:50 +02:00
parent 0cdecca141
commit 37b29ef2fa
5 changed files with 82 additions and 33 deletions
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79
src/scripting.c
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@ -412,45 +412,57 @@ void luaLoadLibraries(lua_State *lua) {
#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";
/* 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; j < 26; j++) code = sdscatlen(code,s[j],strlen(s[j]));
luaL_loadbuffer(lua,code,sdslen(code),"strict_lua");
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.
@ -543,7 +555,8 @@ void scriptingInit(void) {
/* 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;
}