X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/63505e0b59f5584f87ebe2f0d711c6d405b85b4b..717145c1a3302f4a20746dce8c885ee590e0f0e2:/src/scripting.c diff --git a/src/scripting.c b/src/scripting.c index ce1f0877..a5f5683e 100644 --- a/src/scripting.c +++ b/src/scripting.c @@ -15,6 +15,7 @@ char *redisProtocolToLuaType_Error(lua_State *lua, char *reply); char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply); int redis_math_random (lua_State *L); int redis_math_randomseed (lua_State *L); +void sha1hex(char *digest, char *script, size_t len); /* Take a Redis reply in the Redis protocol format and convert it into a * Lua type. Thanks to this function, and the introduction of not connected @@ -206,15 +207,45 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) { goto cleanup; } + /* There are commands that are not allowed inside scripts. */ if (cmd->flags & REDIS_CMD_NOSCRIPT) { luaPushError(lua, "This Redis command is not allowed from scripts"); goto cleanup; } - if (cmd->flags & REDIS_CMD_WRITE && server.lua_random_dirty) { - luaPushError(lua, - "Write commands not allowed after non deterministic commands"); - goto cleanup; + /* Write commands are forbidden against read-only slaves, or if a + * command marked as non-deterministic was already called in the context + * of this script. */ + if (cmd->flags & REDIS_CMD_WRITE) { + if (server.lua_random_dirty) { + luaPushError(lua, + "Write commands not allowed after non deterministic commands"); + goto cleanup; + } else if (server.masterhost && server.repl_slave_ro && + !(server.lua_caller->flags & REDIS_MASTER)) + { + luaPushError(lua, shared.roslaveerr->ptr); + goto cleanup; + } else if (server.stop_writes_on_bgsave_err && + server.saveparamslen > 0 && + server.lastbgsave_status == REDIS_ERR) + { + luaPushError(lua, shared.bgsaveerr->ptr); + goto cleanup; + } + } + + /* If we reached the memory limit configured via maxmemory, commands that + * could enlarge the memory usage are not allowed, but only if this is the + * first write in the context of this script, otherwise we can't stop + * in the middle. */ + if (server.maxmemory && server.lua_write_dirty == 0 && + (cmd->flags & REDIS_CMD_DENYOOM)) + { + if (freeMemoryIfNeeded() == REDIS_ERR) { + luaPushError(lua, shared.oomerr->ptr); + goto cleanup; + } } if (cmd->flags & REDIS_CMD_RANDOM) server.lua_random_dirty = 1; @@ -276,6 +307,25 @@ int luaRedisPCallCommand(lua_State *lua) { return luaRedisGenericCommand(lua,0); } +/* This adds redis.sha1hex(string) to Lua scripts using the same hashing + * function used for sha1ing lua scripts. */ +int luaRedisSha1hexCommand(lua_State *lua) { + int argc = lua_gettop(lua); + char digest[41]; + size_t len; + char *s; + + if (argc != 1) { + luaPushError(lua, "wrong number of arguments"); + return 1; + } + + s = (char*)lua_tolstring(lua,1,&len); + sha1hex(digest,s,len); + lua_pushstring(lua,digest); + return 1; +} + int luaLogCommand(lua_State *lua) { int j, argc = lua_gettop(lua); int level; @@ -362,13 +412,59 @@ void luaLoadLibraries(lua_State *lua) { #endif } +/* Remove a functions that we don't want to expose to the Redis scripting + * environment. */ +void luaRemoveUnsupportedFunctions(lua_State *lua) { + lua_pushnil(lua); + lua_setglobal(lua,"loadfile"); +} + +/* 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. * See scriptingReset() for more information. */ void scriptingInit(void) { lua_State *lua = lua_open(); + luaLoadLibraries(lua); + luaRemoveUnsupportedFunctions(lua); /* Initialize a dictionary we use to map SHAs to scripts. * This is useful for replication, as we need to replicate EVALSHA @@ -409,6 +505,11 @@ void scriptingInit(void) { lua_pushnumber(lua,REDIS_WARNING); lua_settable(lua,-3); + /* redis.sha1hex */ + lua_pushstring(lua, "sha1hex"); + lua_pushcfunction(lua, luaRedisSha1hexCommand); + lua_settable(lua, -3); + /* Finally set the table as 'redis' global var. */ lua_setglobal(lua,"redis"); @@ -433,7 +534,7 @@ 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; } @@ -461,10 +567,13 @@ void scriptingReset(void) { scriptingInit(); } -/* Hash the scripit into a SHA1 digest. We use this as Lua function name. - * Digest should point to a 41 bytes buffer: 40 for SHA1 converted into an +/* Perform the SHA1 of the input string. We use this both for hasing script + * bodies in order to obtain the Lua function name, and in the implementation + * of redis.sha1(). + * + * 'digest' should point to a 41 bytes buffer: 40 for SHA1 converted into an * hexadecimal number, plus 1 byte for null term. */ -void hashScript(char *digest, char *script, size_t len) { +void sha1hex(char *digest, char *script, size_t len) { SHA1_CTX ctx; unsigned char hash[20]; char *cset = "0123456789abcdef"; @@ -576,7 +685,7 @@ 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); @@ -637,7 +746,7 @@ void evalGenericCommand(redisClient *c, int evalsha) { funcname[1] = '_'; if (!evalsha) { /* Hash the code if this is an EVAL call */ - hashScript(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr)); + sha1hex(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr)); } else { /* We already have the SHA if it is a EVALSHA */ int j; @@ -811,7 +920,7 @@ void scriptCommand(redisClient *c) { funcname[0] = 'f'; funcname[1] = '_'; - hashScript(funcname+2,c->argv[2]->ptr,sdslen(c->argv[2]->ptr)); + sha1hex(funcname+2,c->argv[2]->ptr,sdslen(c->argv[2]->ptr)); sha = sdsnewlen(funcname+2,40); if (dictFind(server.lua_scripts,sha) == NULL) { if (luaCreateFunction(c,server.lua,funcname,c->argv[2])