Globals protection global() function modified for speed and correctness.

[redis.git] / src / scripting.c

diff --git a/src/scripting.c b/src/scripting.c
index 2eac840c52e5707829a57f5deab6950d9bf086cc..44ceb1e284ccd03f690b6fa3cc7eeeea94f6696f 100644 (file)
--- 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);
 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
 
 /* 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


@@ -206,22 +207,53 @@ int luaRedisGenericCommand(lua_State *lua, int raise_error) {
         goto cleanup;
     }
 
         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_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;
     if (cmd->flags & REDIS_CMD_WRITE) server.lua_write_dirty = 1;
 
     /* Run the command */
     }
 
     if (cmd->flags & REDIS_CMD_RANDOM) server.lua_random_dirty = 1;
     if (cmd->flags & REDIS_CMD_WRITE) server.lua_write_dirty = 1;
 
     /* Run the command */

-    cmd->proc(c);
+    c->cmd = cmd;
+    call(c,REDIS_CALL_SLOWLOG | REDIS_CALL_STATS);

 
     /* Convert the result of the Redis command into a suitable Lua type.
      * The first thing we need is to create a single string from the client
 
     /* Convert the result of the Redis command into a suitable Lua type.
      * The first thing we need is to create a single string from the client


@@ -275,6 +307,25 @@ int luaRedisPCallCommand(lua_State *lua) {
     return luaRedisGenericCommand(lua,0);
 }
 
     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;
 int luaLogCommand(lua_State *lua) {
     int j, argc = lua_gettop(lua);
     int level;


@@ -342,6 +393,8 @@ void luaLoadLib(lua_State *lua, const char *libname, lua_CFunction luafunc) {
 }
 
 LUALIB_API int (luaopen_cjson) (lua_State *L);
 }
 
 LUALIB_API int (luaopen_cjson) (lua_State *L);

+LUALIB_API int (luaopen_struct) (lua_State *L);
+LUALIB_API int (luaopen_cmsgpack) (lua_State *L);

 
 void luaLoadLibraries(lua_State *lua) {
     luaLoadLib(lua, "", luaopen_base);
 
 void luaLoadLibraries(lua_State *lua) {
     luaLoadLib(lua, "", luaopen_base);


@@ -349,7 +402,9 @@ void luaLoadLibraries(lua_State *lua) {
     luaLoadLib(lua, LUA_STRLIBNAME, luaopen_string);
     luaLoadLib(lua, LUA_MATHLIBNAME, luaopen_math);
     luaLoadLib(lua, LUA_DBLIBNAME, luaopen_debug); 
     luaLoadLib(lua, LUA_STRLIBNAME, luaopen_string);
     luaLoadLib(lua, LUA_MATHLIBNAME, luaopen_math);
     luaLoadLib(lua, LUA_DBLIBNAME, luaopen_debug); 

-    luaLoadLib(lua, "cjson", luaopen_cjson); 
+    luaLoadLib(lua, "cjson", luaopen_cjson);
+    luaLoadLib(lua, "struct", luaopen_struct);
+    luaLoadLib(lua, "cmsgpack", luaopen_cmsgpack);

 
 #if 0 /* Stuff that we don't load currently, for sandboxing concerns. */
     luaLoadLib(lua, LUA_LOADLIBNAME, luaopen_package);
 
 #if 0 /* Stuff that we don't load currently, for sandboxing concerns. */
     luaLoadLib(lua, LUA_LOADLIBNAME, luaopen_package);


@@ -357,6 +412,61 @@ void luaLoadLibraries(lua_State *lua) {
 #endif
 }
 
 #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.
+ * 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 = 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.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++]="  local nargs = select(\"#\",...)\n";
+    s[j++]="  for i = 1, nargs do\n";
+    s[j++]="    local v = select(i,...)\n";
+    s[j++]="    mt.declared[v] = true\n";
+    s[j++]="  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.
 /* Initialize the scripting environment.
  * It is possible to call this function to reset the scripting environment
  * assuming that we call scriptingRelease() before.


@@ -404,6 +514,11 @@ void scriptingInit(void) {
     lua_pushnumber(lua,REDIS_WARNING);
     lua_settable(lua,-3);
 
     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");
 
     /* Finally set the table as 'redis' global var. */
     lua_setglobal(lua,"redis");
 


@@ -441,6 +556,12 @@ void scriptingInit(void) {
         server.lua_client->flags |= REDIS_LUA_CLIENT;
     }
 
         server.lua_client->flags |= 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. */
+    if (server.lua_protect_globals)
+        scriptingEnableGlobalsProtection(lua);
+

     server.lua = lua;
 }
 
     server.lua = lua;
 }
 


@@ -456,10 +577,13 @@ void scriptingReset(void) {
     scriptingInit();
 }
 
     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. */
  * 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";
     SHA1_CTX ctx;
     unsigned char hash[20];
     char *cset = "0123456789abcdef";


@@ -632,7 +756,7 @@ void evalGenericCommand(redisClient *c, int evalsha) {
     funcname[1] = '_';
     if (!evalsha) {
         /* Hash the code if this is an EVAL call */
     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;
     } else {
         /* We already have the SHA if it is a EVALSHA */
         int j;


@@ -806,7 +930,7 @@ void scriptCommand(redisClient *c) {
 
         funcname[0] = 'f';
         funcname[1] = '_';
 
         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])
         sha = sdsnewlen(funcname+2,40);
         if (dictFind(server.lua_scripts,sha) == NULL) {
             if (luaCreateFunction(c,server.lua,funcname,c->argv[2])