diff --git a/src/scripting.c b/src/scripting.c index 0f876961..4c7de33b 100644 --- a/src/scripting.c +++ b/src/scripting.c @@ -412,6 +412,43 @@ void luaLoadLibraries(lua_State *lua) { #endif } +/* 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. */ +void scriptingEnableGlobalsProtection(lua_State *lua) { + char *s[32]; + sds code = sdsempty(); + int j = 0; + + /* strict.lua from: http://metalua.luaforge.net/src/lib/strict.lua.html. + * Modified to be adapted to Redis. */ + s[j++]="local mt = {}\n"; + s[j++]="setmetatable(_G, mt)\n"; + s[j++]="mt.__newindex = function (t, n, v)\n"; + s[j++]=" if 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(\"Script attempted to create global variable '\"..tostring(n)..\"'\", 2)\n"; + s[j++]=" end\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 debug.getinfo(2, \"S\").what ~= \"C\" then\n"; + s[j++]=" error(\"Script attempted to access unexisting global variable '\"..tostring(n)..\"'\", 2)\n"; + s[j++]=" end\n"; + s[j++]=" return rawget(t, n)\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); +} + /* Initialize the scripting environment. * It is possible to call this function to reset the scripting environment * assuming that we call scriptingRelease() before. @@ -488,7 +525,7 @@ void scriptingInit(void) { " if b == false then b = '' end\n" " return aflags |= REDIS_LUA_CLIENT; } + /* 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. */ + scriptingEnableGlobalsProtection(lua); + server.lua = lua; } @@ -634,7 +676,7 @@ int luaCreateFunction(redisClient *c, lua_State *lua, char *funcname, robj *body funcdef = sdscatlen(funcdef,body->ptr,sdslen(body->ptr)); funcdef = sdscatlen(funcdef," end",4); - if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"func definition")) { + if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"@user_script")) { addReplyErrorFormat(c,"Error compiling script (new function): %s\n", lua_tostring(lua,-1)); lua_pop(lua,1); diff --git a/tests/unit/scripting.tcl b/tests/unit/scripting.tcl index b9307cc1..009c1347 100644 --- a/tests/unit/scripting.tcl +++ b/tests/unit/scripting.tcl @@ -219,6 +219,38 @@ start_server {tags {"scripting"}} { list [r eval {return redis.sha1hex('')} 0] \ [r eval {return redis.sha1hex('Pizza & Mandolino')} 0] } {da39a3ee5e6b4b0d3255bfef95601890afd80709 74822d82031af7493c20eefa13bd07ec4fada82f} + + test {Globals protection reading an undeclared global variable} { + catch {r eval {return a} 0} e + set e + } {*ERR*attempted to access unexisting global*} + + test {Globals protection setting an undeclared global*} { + catch {r eval {a=10} 0} e + set e + } {*ERR*attempted to create global*} + + test {Test an example script DECR_IF_GT} { + set decr_if_gt { + local current + + current = redis.call('get',KEYS[1]) + if not current then return nil end + if current > ARGV[1] then + return redis.call('decr',KEYS[1]) + else + return redis.call('get',KEYS[1]) + end + } + r set foo 5 + set res {} + lappend res [r eval $decr_if_gt 1 foo 2] + lappend res [r eval $decr_if_gt 1 foo 2] + lappend res [r eval $decr_if_gt 1 foo 2] + lappend res [r eval $decr_if_gt 1 foo 2] + lappend res [r eval $decr_if_gt 1 foo 2] + set res + } {4 3 2 2 2} } start_server {tags {"scripting repl"}} {