/* * CDDL HEADER START * * This file and its contents are supplied under the terms of the * Common Development and Distribution License ("CDDL"), version 1.0. * You may only use this file in accordance with the terms of version * 1.0 of the CDDL. * * A full copy of the text of the CDDL should have accompanied this * source. A copy of the CDDL is also available via the Internet at * http://www.illumos.org/license/CDDL. * * CDDL HEADER END */ /* * Copyright (c) 2016, 2018 by Delphix. All rights reserved. */ /* * ZFS Channel Programs (ZCP) * * The ZCP interface allows various ZFS commands and operations ZFS * administrative operations (e.g. creating and destroying snapshots, typically * performed via an ioctl to /dev/zfs by the zfs(8) command and * libzfs/libzfs_core) to be run * programmatically as a Lua script. A ZCP * script is run as a dsl_sync_task and fully executed during one transaction * group sync. This ensures that no other changes can be written concurrently * with a running Lua script. Combining multiple calls to the exposed ZFS * functions into one script gives a number of benefits: * * 1. Atomicity. For some compound or iterative operations, it's useful to be * able to guarantee that the state of a pool has not changed between calls to * ZFS. * * 2. Performance. If a large number of changes need to be made (e.g. deleting * many filesystems), there can be a significant performance penalty as a * result of the need to wait for a transaction group sync to pass for every * single operation. When expressed as a single ZCP script, all these changes * can be performed at once in one txg sync. * * A modified version of the Lua 5.2 interpreter is used to run channel program * scripts. The Lua 5.2 manual can be found at: * * http://www.lua.org/manual/5.2/ * * If being run by a user (via an ioctl syscall), executing a ZCP script * requires root privileges in the global zone. * * Scripts are passed to zcp_eval() as a string, then run in a synctask by * zcp_eval_sync(). Arguments can be passed into the Lua script as an nvlist, * which will be converted to a Lua table. Similarly, values returned from * a ZCP script will be converted to an nvlist. See zcp_lua_to_nvlist_impl() * for details on exact allowed types and conversion. * * ZFS functionality is exposed to a ZCP script as a library of function calls. * These calls are sorted into submodules, such as zfs.list and zfs.sync, for * iterators and synctasks, respectively. Each of these submodules resides in * its own source file, with a zcp_*_info structure describing each library * call in the submodule. * * Error handling in ZCP scripts is handled by a number of different methods * based on severity: * * 1. Memory and time limits are in place to prevent a channel program from * consuming excessive system or running forever. If one of these limits is * hit, the channel program will be stopped immediately and return from * zcp_eval() with an error code. No attempt will be made to roll back or undo * any changes made by the channel program before the error occurred. * Consumers invoking zcp_eval() from elsewhere in the kernel may pass a time * limit of 0, disabling the time limit. * * 2. Internal Lua errors can occur as a result of a syntax error, calling a * library function with incorrect arguments, invoking the error() function, * failing an assert(), or other runtime errors. In these cases the channel * program will stop executing and return from zcp_eval() with an error code. * In place of a return value, an error message will also be returned in the * 'result' nvlist containing information about the error. No attempt will be * made to roll back or undo any changes made by the channel program before the * error occurred. * * 3. If an error occurs inside a ZFS library call which returns an error code, * the error is returned to the Lua script to be handled as desired. * * In the first two cases, Lua's error-throwing mechanism is used, which * longjumps out of the script execution with luaL_error() and returns with the * error. * * See zfs-program(8) for more information on high level usage. */ #include <sys/lua/lua.h> #include <sys/lua/lualib.h> #include <sys/lua/lauxlib.h> #include <sys/dsl_prop.h> #include <sys/dsl_synctask.h> #include <sys/dsl_dataset.h> #include <sys/zcp.h> #include <sys/zcp_iter.h> #include <sys/zcp_prop.h> #include <sys/zcp_global.h> #include <sys/zvol.h> #ifndef KM_NORMALPRI #define KM_NORMALPRI 0 #endif #define ZCP_NVLIST_MAX_DEPTH 20 static const uint64_t zfs_lua_check_instrlimit_interval = 100; uint64_t zfs_lua_max_instrlimit = ZCP_MAX_INSTRLIMIT; uint64_t zfs_lua_max_memlimit = ZCP_MAX_MEMLIMIT; /* * Forward declarations for mutually recursive functions */ static int zcp_nvpair_value_to_lua(lua_State *, nvpair_t *, char *, int); static int zcp_lua_to_nvlist_impl(lua_State *, int, nvlist_t *, const char *, int); /* * The outer-most error callback handler for use with lua_pcall(). On * error Lua will call this callback with a single argument that * represents the error value. In most cases this will be a string * containing an error message, but channel programs can use Lua's * error() function to return arbitrary objects as errors. This callback * returns (on the Lua stack) the original error object along with a traceback. * * Fatal Lua errors can occur while resources are held, so we also call any * registered cleanup function here. */ static int zcp_error_handler(lua_State *state) { const char *msg; zcp_cleanup(state); VERIFY3U(1, ==, lua_gettop(state)); msg = lua_tostring(state, 1); luaL_traceback(state, state, msg, 1); return (1); } int zcp_argerror(lua_State *state, int narg, const char *msg, ...) { va_list alist; va_start(alist, msg); const char *buf = lua_pushvfstring(state, msg, alist); va_end(alist); return (luaL_argerror(state, narg, buf)); } /* * Install a new cleanup function, which will be invoked with the given * opaque argument if a fatal error causes the Lua interpreter to longjump out * of a function call. * * If an error occurs, the cleanup function will be invoked exactly once and * then unregistered. * * Returns the registered cleanup handler so the caller can deregister it * if no error occurs. */ zcp_cleanup_handler_t * zcp_register_cleanup(lua_State *state, zcp_cleanup_t cleanfunc, void *cleanarg) { zcp_run_info_t *ri = zcp_run_info(state); zcp_cleanup_handler_t *zch = kmem_alloc(sizeof (*zch), KM_SLEEP); zch->zch_cleanup_func = cleanfunc; zch->zch_cleanup_arg = cleanarg; list_insert_head(&ri->zri_cleanup_handlers, zch); return (zch); } void zcp_deregister_cleanup(lua_State *state, zcp_cleanup_handler_t *zch) { zcp_run_info_t *ri = zcp_run_info(state); list_remove(&ri->zri_cleanup_handlers, zch); kmem_free(zch, sizeof (*zch)); } /* * Execute the currently registered cleanup handlers then free them and * destroy the handler list. */ void zcp_cleanup(lua_State *state) { zcp_run_info_t *ri = zcp_run_info(state); for (zcp_cleanup_handler_t *zch = list_remove_head(&ri->zri_cleanup_handlers); zch != NULL; zch = list_remove_head(&ri->zri_cleanup_handlers)) { zch->zch_cleanup_func(zch->zch_cleanup_arg); kmem_free(zch, sizeof (*zch)); } } /* * Convert the lua table at the given index on the Lua stack to an nvlist * and return it. * * If the table can not be converted for any reason, NULL is returned and * an error message is pushed onto the Lua stack. */ static nvlist_t * zcp_table_to_nvlist(lua_State *state, int index, int depth) { nvlist_t *nvl; /* * Converting a Lua table to an nvlist with key uniqueness checking is * O(n^2) in the number of keys in the nvlist, which can take a long * time when we return a large table from a channel program. * Furthermore, Lua's table interface *almost* guarantees unique keys * on its own (details below). Therefore, we don't use fnvlist_alloc() * here to avoid the built-in uniqueness checking. * * The *almost* is because it's possible to have key collisions between * e.g. the string "1" and the number 1, or the string "true" and the * boolean true, so we explicitly check that when we're looking at a * key which is an integer / boolean or a string that can be parsed as * one of those types. In the worst case this could still devolve into * O(n^2), so we only start doing these checks on boolean/integer keys * once we've seen a string key which fits this weird usage pattern. * * Ultimately, we still want callers to know that the keys in this * nvlist are unique, so before we return this we set the nvlist's * flags to reflect that. */ VERIFY0(nvlist_alloc(&nvl, 0, KM_SLEEP)); /* * Push an empty stack slot where lua_next() will store each * table key. */ lua_pushnil(state); boolean_t saw_str_could_collide = B_FALSE; while (lua_next(state, index) != 0) { /* * The next key-value pair from the table at index is * now on the stack, with the key at stack slot -2 and * the value at slot -1. */ int err = 0; char buf[32]; const char *key = NULL; boolean_t key_could_collide = B_FALSE; switch (lua_type(state, -2)) { case LUA_TSTRING: key = lua_tostring(state, -2); /* check if this could collide with a number or bool */ long long tmp; int parselen; if ((sscanf(key, "%lld%n", &tmp, &parselen) > 0 && parselen == strlen(key)) || strcmp(key, "true") == 0 || strcmp(key, "false") == 0) { key_could_collide = B_TRUE; saw_str_could_collide = B_TRUE; } break; case LUA_TBOOLEAN: key = (lua_toboolean(state, -2) == B_TRUE ? "true" : "false"); if (saw_str_could_collide) { key_could_collide = B_TRUE; } break; case LUA_TNUMBER: (void) snprintf(buf, sizeof (buf), "%lld", (longlong_t)lua_tonumber(state, -2)); key = buf; if (saw_str_could_collide) { key_could_collide = B_TRUE; } break; default: fnvlist_free(nvl); (void) lua_pushfstring(state, "Invalid key " "type '%s' in table", lua_typename(state, lua_type(state, -2))); return (NULL); } /* * Check for type-mismatched key collisions, and throw an error. */ if (key_could_collide && nvlist_exists(nvl, key)) { fnvlist_free(nvl); (void) lua_pushfstring(state, "Collision of " "key '%s' in table", key); return (NULL); } /* * Recursively convert the table value and insert into * the new nvlist with the parsed key. To prevent * stack overflow on circular or heavily nested tables, * we track the current nvlist depth. */ if (depth >= ZCP_NVLIST_MAX_DEPTH) { fnvlist_free(nvl); (void) lua_pushfstring(state, "Maximum table " "depth (%d) exceeded for table", ZCP_NVLIST_MAX_DEPTH); return (NULL); } err = zcp_lua_to_nvlist_impl(state, -1, nvl, key, depth + 1); if (err != 0) { fnvlist_free(nvl); /* * Error message has been pushed to the lua * stack by the recursive call. */ return (NULL); } /* * Pop the value pushed by lua_next(). */ lua_pop(state, 1); } /* * Mark the nvlist as having unique keys. This is a little ugly, but we * ensured above that there are no duplicate keys in the nvlist. */ nvl->nvl_nvflag |= NV_UNIQUE_NAME; return (nvl); } /* * Convert a value from the given index into the lua stack to an nvpair, adding * it to an nvlist with the given key. * * Values are converted as follows: * * string -> string * number -> int64 * boolean -> boolean * nil -> boolean (no value) * * Lua tables are converted to nvlists and then inserted. The table's keys * are converted to strings then used as keys in the nvlist to store each table * element. Keys are converted as follows: * * string -> no change * number -> "%lld" * boolean -> "true" | "false" * nil -> error * * In the case of a key collision, an error is thrown. * * If an error is encountered, a nonzero error code is returned, and an error * string will be pushed onto the Lua stack. */ static int zcp_lua_to_nvlist_impl(lua_State *state, int index, nvlist_t *nvl, const char *key, int depth) { /* * Verify that we have enough remaining space in the lua stack to parse * a key-value pair and push an error. */ if (!lua_checkstack(state, 3)) { (void) lua_pushstring(state, "Lua stack overflow"); return (1); } index = lua_absindex(state, index); switch (lua_type(state, index)) { case LUA_TNIL: fnvlist_add_boolean(nvl, key); break; case LUA_TBOOLEAN: fnvlist_add_boolean_value(nvl, key, lua_toboolean(state, index)); break; case LUA_TNUMBER: fnvlist_add_int64(nvl, key, lua_tonumber(state, index)); break; case LUA_TSTRING: fnvlist_add_string(nvl, key, lua_tostring(state, index)); break; case LUA_TTABLE: { nvlist_t *value_nvl = zcp_table_to_nvlist(state, index, depth); if (value_nvl == NULL) return (SET_ERROR(EINVAL)); fnvlist_add_nvlist(nvl, key, value_nvl); fnvlist_free(value_nvl); break; } default: (void) lua_pushfstring(state, "Invalid value type '%s' for key '%s'", lua_typename(state, lua_type(state, index)), key); return (SET_ERROR(EINVAL)); } return (0); } /* * Convert a lua value to an nvpair, adding it to an nvlist with the given key. */ static void zcp_lua_to_nvlist(lua_State *state, int index, nvlist_t *nvl, const char *key) { /* * On error, zcp_lua_to_nvlist_impl pushes an error string onto the Lua * stack before returning with a nonzero error code. If an error is * returned, throw a fatal lua error with the given string. */ if (zcp_lua_to_nvlist_impl(state, index, nvl, key, 0) != 0) (void) lua_error(state); } static int zcp_lua_to_nvlist_helper(lua_State *state) { nvlist_t *nv = (nvlist_t *)lua_touserdata(state, 2); const char *key = (const char *)lua_touserdata(state, 1); zcp_lua_to_nvlist(state, 3, nv, key); return (0); } static void zcp_convert_return_values(lua_State *state, nvlist_t *nvl, const char *key, int *result) { int err; VERIFY3U(1, ==, lua_gettop(state)); lua_pushcfunction(state, zcp_lua_to_nvlist_helper); lua_pushlightuserdata(state, (char *)key); lua_pushlightuserdata(state, nvl); lua_pushvalue(state, 1); lua_remove(state, 1); err = lua_pcall(state, 3, 0, 0); /* zcp_lua_to_nvlist_helper */ if (err != 0) { zcp_lua_to_nvlist(state, 1, nvl, ZCP_RET_ERROR); *result = SET_ERROR(ECHRNG); } } /* * Push a Lua table representing nvl onto the stack. If it can't be * converted, return EINVAL, fill in errbuf, and push nothing. errbuf may * be specified as NULL, in which case no error string will be output. * * Most nvlists are converted as simple key->value Lua tables, but we make * an exception for the case where all nvlist entries are BOOLEANs (a string * key without a value). In Lua, a table key pointing to a value of Nil * (no value) is equivalent to the key not existing, so a BOOLEAN nvlist * entry can't be directly converted to a Lua table entry. Nvlists of entirely * BOOLEAN entries are frequently used to pass around lists of datasets, so for * convenience we check for this case, and convert it to a simple Lua array of * strings. */ int zcp_nvlist_to_lua(lua_State *state, nvlist_t *nvl, char *errbuf, int errbuf_len) { nvpair_t *pair; lua_newtable(state); boolean_t has_values = B_FALSE; /* * If the list doesn't have any values, just convert it to a string * array. */ for (pair = nvlist_next_nvpair(nvl, NULL); pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) { if (nvpair_type(pair) != DATA_TYPE_BOOLEAN) { has_values = B_TRUE; break; } } if (!has_values) { int i = 1; for (pair = nvlist_next_nvpair(nvl, NULL); pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) { (void) lua_pushinteger(state, i); (void) lua_pushstring(state, nvpair_name(pair)); (void) lua_settable(state, -3); i++; } } else { for (pair = nvlist_next_nvpair(nvl, NULL); pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) { int err = zcp_nvpair_value_to_lua(state, pair, errbuf, errbuf_len); if (err != 0) { lua_pop(state, 1); return (err); } (void) lua_setfield(state, -2, nvpair_name(pair)); } } return (0); } /* * Push a Lua object representing the value of "pair" onto the stack. * * Only understands boolean_value, string, int64, nvlist, * string_array, and int64_array type values. For other * types, returns EINVAL, fills in errbuf, and pushes nothing. */ static int zcp_nvpair_value_to_lua(lua_State *state, nvpair_t *pair, char *errbuf, int errbuf_len) { int err = 0; if (pair == NULL) { lua_pushnil(state); return (0); } switch (nvpair_type(pair)) { case DATA_TYPE_BOOLEAN_VALUE: (void) lua_pushboolean(state, fnvpair_value_boolean_value(pair)); break; case DATA_TYPE_STRING: (void) lua_pushstring(state, fnvpair_value_string(pair)); break; case DATA_TYPE_INT64: (void) lua_pushinteger(state, fnvpair_value_int64(pair)); break; case DATA_TYPE_NVLIST: err = zcp_nvlist_to_lua(state, fnvpair_value_nvlist(pair), errbuf, errbuf_len); break; case DATA_TYPE_STRING_ARRAY: { const char **strarr; uint_t nelem; (void) nvpair_value_string_array(pair, &strarr, &nelem); lua_newtable(state); for (int i = 0; i < nelem; i++) { (void) lua_pushinteger(state, i + 1); (void) lua_pushstring(state, strarr[i]); (void) lua_settable(state, -3); } break; } case DATA_TYPE_UINT64_ARRAY: { uint64_t *intarr; uint_t nelem; (void) nvpair_value_uint64_array(pair, &intarr, &nelem); lua_newtable(state); for (int i = 0; i < nelem; i++) { (void) lua_pushinteger(state, i + 1); (void) lua_pushinteger(state, intarr[i]); (void) lua_settable(state, -3); } break; } case DATA_TYPE_INT64_ARRAY: { int64_t *intarr; uint_t nelem; (void) nvpair_value_int64_array(pair, &intarr, &nelem); lua_newtable(state); for (int i = 0; i < nelem; i++) { (void) lua_pushinteger(state, i + 1); (void) lua_pushinteger(state, intarr[i]); (void) lua_settable(state, -3); } break; } default: { if (errbuf != NULL) { (void) snprintf(errbuf, errbuf_len, "Unhandled nvpair type %d for key '%s'", nvpair_type(pair), nvpair_name(pair)); } return (SET_ERROR(EINVAL)); } } return (err); } int zcp_dataset_hold_error(lua_State *state, dsl_pool_t *dp, const char *dsname, int error) { if (error == ENOENT) { (void) zcp_argerror(state, 1, "no such dataset '%s'", dsname); return (0); /* not reached; zcp_argerror will longjmp */ } else if (error == EXDEV) { (void) zcp_argerror(state, 1, "dataset '%s' is not in the target pool '%s'", dsname, spa_name(dp->dp_spa)); return (0); /* not reached; zcp_argerror will longjmp */ } else if (error == EIO) { (void) luaL_error(state, "I/O error while accessing dataset '%s'", dsname); return (0); /* not reached; luaL_error will longjmp */ } else if (error != 0) { (void) luaL_error(state, "unexpected error %d while accessing dataset '%s'", error, dsname); return (0); /* not reached; luaL_error will longjmp */ } return (0); } /* * Note: will longjmp (via lua_error()) on error. * Assumes that the dsname is argument #1 (for error reporting purposes). */ dsl_dataset_t * zcp_dataset_hold(lua_State *state, dsl_pool_t *dp, const char *dsname, const void *tag) { dsl_dataset_t *ds; int error = dsl_dataset_hold(dp, dsname, tag, &ds); (void) zcp_dataset_hold_error(state, dp, dsname, error); return (ds); } static int zcp_debug(lua_State *); static const zcp_lib_info_t zcp_debug_info = { .name = "debug", .func = zcp_debug, .pargs = { { .za_name = "debug string", .za_lua_type = LUA_TSTRING }, {NULL, 0} }, .kwargs = { {NULL, 0} } }; static int zcp_debug(lua_State *state) { const char *dbgstring; zcp_run_info_t *ri = zcp_run_info(state); const zcp_lib_info_t *libinfo = &zcp_debug_info; zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs); dbgstring = lua_tostring(state, 1); zfs_dbgmsg("txg %lld ZCP: %s", (longlong_t)ri->zri_tx->tx_txg, dbgstring); return (0); } static int zcp_exists(lua_State *); static const zcp_lib_info_t zcp_exists_info = { .name = "exists", .func = zcp_exists, .pargs = { { .za_name = "dataset", .za_lua_type = LUA_TSTRING }, {NULL, 0} }, .kwargs = { {NULL, 0} } }; static int zcp_exists(lua_State *state) { zcp_run_info_t *ri = zcp_run_info(state); dsl_pool_t *dp = ri->zri_pool; const zcp_lib_info_t *libinfo = &zcp_exists_info; zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs); const char *dsname = lua_tostring(state, 1); dsl_dataset_t *ds; int error = dsl_dataset_hold(dp, dsname, FTAG, &ds); if (error == 0) { dsl_dataset_rele(ds, FTAG); lua_pushboolean(state, B_TRUE); } else if (error == ENOENT) { lua_pushboolean(state, B_FALSE); } else if (error == EXDEV) { return (luaL_error(state, "dataset '%s' is not in the " "target pool", dsname)); } else if (error == EIO) { return (luaL_error(state, "I/O error opening dataset '%s'", dsname)); } else if (error != 0) { return (luaL_error(state, "unexpected error %d", error)); } return (1); } /* * Allocate/realloc/free a buffer for the lua interpreter. * * When nsize is 0, behaves as free() and returns NULL. * * If ptr is NULL, behaves as malloc() and returns an allocated buffer of size * at least nsize. * * Otherwise, behaves as realloc(), changing the allocation from osize to nsize. * Shrinking the buffer size never fails. * * The original allocated buffer size is stored as a uint64 at the beginning of * the buffer to avoid actually reallocating when shrinking a buffer, since lua * requires that this operation never fail. */ static void * zcp_lua_alloc(void *ud, void *ptr, size_t osize, size_t nsize) { zcp_alloc_arg_t *allocargs = ud; if (nsize == 0) { if (ptr != NULL) { int64_t *allocbuf = (int64_t *)ptr - 1; int64_t allocsize = *allocbuf; ASSERT3S(allocsize, >, 0); ASSERT3S(allocargs->aa_alloc_remaining + allocsize, <=, allocargs->aa_alloc_limit); allocargs->aa_alloc_remaining += allocsize; vmem_free(allocbuf, allocsize); } return (NULL); } else if (ptr == NULL) { int64_t *allocbuf; int64_t allocsize = nsize + sizeof (int64_t); if (!allocargs->aa_must_succeed && (allocsize <= 0 || allocsize > allocargs->aa_alloc_remaining)) { return (NULL); } allocbuf = vmem_alloc(allocsize, KM_SLEEP); allocargs->aa_alloc_remaining -= allocsize; *allocbuf = allocsize; return (allocbuf + 1); } else if (nsize <= osize) { /* * If shrinking the buffer, lua requires that the reallocation * never fail. */ return (ptr); } else { ASSERT3U(nsize, >, osize); uint64_t *luabuf = zcp_lua_alloc(ud, NULL, 0, nsize); if (luabuf == NULL) { return (NULL); } (void) memcpy(luabuf, ptr, osize); VERIFY3P(zcp_lua_alloc(ud, ptr, osize, 0), ==, NULL); return (luabuf); } } static void zcp_lua_counthook(lua_State *state, lua_Debug *ar) { (void) ar; lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY); zcp_run_info_t *ri = lua_touserdata(state, -1); /* * Check if we were canceled while waiting for the * txg to sync or from our open context thread */ if (ri->zri_canceled || (!ri->zri_sync && issig(JUSTLOOKING) && issig(FORREAL))) { ri->zri_canceled = B_TRUE; (void) lua_pushstring(state, "Channel program was canceled."); (void) lua_error(state); /* Unreachable */ } /* * Check how many instructions the channel program has * executed so far, and compare against the limit. */ ri->zri_curinstrs += zfs_lua_check_instrlimit_interval; if (ri->zri_maxinstrs != 0 && ri->zri_curinstrs > ri->zri_maxinstrs) { ri->zri_timed_out = B_TRUE; (void) lua_pushstring(state, "Channel program timed out."); (void) lua_error(state); /* Unreachable */ } } static int zcp_panic_cb(lua_State *state) { panic("unprotected error in call to Lua API (%s)\n", lua_tostring(state, -1)); return (0); } static void zcp_eval_impl(dmu_tx_t *tx, zcp_run_info_t *ri) { int err; lua_State *state = ri->zri_state; VERIFY3U(3, ==, lua_gettop(state)); /* finish initializing our runtime state */ ri->zri_pool = dmu_tx_pool(tx); ri->zri_tx = tx; list_create(&ri->zri_cleanup_handlers, sizeof (zcp_cleanup_handler_t), offsetof(zcp_cleanup_handler_t, zch_node)); /* * Store the zcp_run_info_t struct for this run in the Lua registry. * Registry entries are not directly accessible by the Lua scripts but * can be accessed by our callbacks. */ lua_pushlightuserdata(state, ri); lua_setfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY); VERIFY3U(3, ==, lua_gettop(state)); /* * Tell the Lua interpreter to call our handler every count * instructions. Channel programs that execute too many instructions * should die with ETIME. */ (void) lua_sethook(state, zcp_lua_counthook, LUA_MASKCOUNT, zfs_lua_check_instrlimit_interval); /* * Tell the Lua memory allocator to stop using KM_SLEEP before handing * off control to the channel program. Channel programs that use too * much memory should die with ENOSPC. */ ri->zri_allocargs->aa_must_succeed = B_FALSE; /* * Call the Lua function that open-context passed us. This pops the * function and its input from the stack and pushes any return * or error values. */ err = lua_pcall(state, 1, LUA_MULTRET, 1); /* * Let Lua use KM_SLEEP while we interpret the return values. */ ri->zri_allocargs->aa_must_succeed = B_TRUE; /* * Remove the error handler callback from the stack. At this point, * there shouldn't be any cleanup handler registered in the handler * list (zri_cleanup_handlers), regardless of whether it ran or not. */ list_destroy(&ri->zri_cleanup_handlers); lua_remove(state, 1); switch (err) { case LUA_OK: { /* * Lua supports returning multiple values in a single return * statement. Return values will have been pushed onto the * stack: * 1: Return value 1 * 2: Return value 2 * 3: etc... * To simplify the process of retrieving a return value from a * channel program, we disallow returning more than one value * to ZFS from the Lua script, yielding a singleton return * nvlist of the form { "return": Return value 1 }. */ int return_count = lua_gettop(state); if (return_count == 1) { ri->zri_result = 0; zcp_convert_return_values(state, ri->zri_outnvl, ZCP_RET_RETURN, &ri->zri_result); } else if (return_count > 1) { ri->zri_result = SET_ERROR(ECHRNG); lua_settop(state, 0); (void) lua_pushfstring(state, "Multiple return " "values not supported"); zcp_convert_return_values(state, ri->zri_outnvl, ZCP_RET_ERROR, &ri->zri_result); } break; } case LUA_ERRRUN: case LUA_ERRGCMM: { /* * The channel program encountered a fatal error within the * script, such as failing an assertion, or calling a function * with incompatible arguments. The error value and the * traceback generated by zcp_error_handler() should be on the * stack. */ VERIFY3U(1, ==, lua_gettop(state)); if (ri->zri_timed_out) { ri->zri_result = SET_ERROR(ETIME); } else if (ri->zri_canceled) { ri->zri_result = SET_ERROR(EINTR); } else { ri->zri_result = SET_ERROR(ECHRNG); } zcp_convert_return_values(state, ri->zri_outnvl, ZCP_RET_ERROR, &ri->zri_result); if (ri->zri_result == ETIME && ri->zri_outnvl != NULL) { (void) nvlist_add_uint64(ri->zri_outnvl, ZCP_ARG_INSTRLIMIT, ri->zri_curinstrs); } break; } case LUA_ERRERR: { /* * The channel program encountered a fatal error within the * script, and we encountered another error while trying to * compute the traceback in zcp_error_handler(). We can only * return the error message. */ VERIFY3U(1, ==, lua_gettop(state)); if (ri->zri_timed_out) { ri->zri_result = SET_ERROR(ETIME); } else if (ri->zri_canceled) { ri->zri_result = SET_ERROR(EINTR); } else { ri->zri_result = SET_ERROR(ECHRNG); } zcp_convert_return_values(state, ri->zri_outnvl, ZCP_RET_ERROR, &ri->zri_result); break; } case LUA_ERRMEM: /* * Lua ran out of memory while running the channel program. * There's not much we can do. */ ri->zri_result = SET_ERROR(ENOSPC); break; default: VERIFY0(err); } } static void zcp_pool_error(zcp_run_info_t *ri, const char *poolname, int error) { ri->zri_result = SET_ERROR(ECHRNG); lua_settop(ri->zri_state, 0); (void) lua_pushfstring(ri->zri_state, "Could not open pool: %s " "errno: %d", poolname, error); zcp_convert_return_values(ri->zri_state, ri->zri_outnvl, ZCP_RET_ERROR, &ri->zri_result); } /* * This callback is called when txg_wait_synced_sig encountered a signal. * The txg_wait_synced_sig will continue to wait for the txg to complete * after calling this callback. */ static void zcp_eval_sig(void *arg, dmu_tx_t *tx) { (void) tx; zcp_run_info_t *ri = arg; ri->zri_canceled = B_TRUE; } static void zcp_eval_sync(void *arg, dmu_tx_t *tx) { zcp_run_info_t *ri = arg; /* * Open context should have setup the stack to contain: * 1: Error handler callback * 2: Script to run (converted to a Lua function) * 3: nvlist input to function (converted to Lua table or nil) */ VERIFY3U(3, ==, lua_gettop(ri->zri_state)); zcp_eval_impl(tx, ri); } static void zcp_eval_open(zcp_run_info_t *ri, const char *poolname) { int error; dsl_pool_t *dp; dmu_tx_t *tx; /* * See comment from the same assertion in zcp_eval_sync(). */ VERIFY3U(3, ==, lua_gettop(ri->zri_state)); error = dsl_pool_hold(poolname, FTAG, &dp); if (error != 0) { zcp_pool_error(ri, poolname, error); return; } /* * As we are running in open-context, we have no transaction associated * with the channel program. At the same time, functions from the * zfs.check submodule need to be associated with a transaction as * they are basically dry-runs of their counterparts in the zfs.sync * submodule. These functions should be able to run in open-context. * Therefore we create a new transaction that we later abort once * the channel program has been evaluated. */ tx = dmu_tx_create_dd(dp->dp_mos_dir); zcp_eval_impl(tx, ri); dmu_tx_abort(tx); dsl_pool_rele(dp, FTAG); } int zcp_eval(const char *poolname, const char *program, boolean_t sync, uint64_t instrlimit, uint64_t memlimit, nvpair_t *nvarg, nvlist_t *outnvl) { int err; lua_State *state; zcp_run_info_t runinfo; if (instrlimit > zfs_lua_max_instrlimit) return (SET_ERROR(EINVAL)); if (memlimit == 0 || memlimit > zfs_lua_max_memlimit) return (SET_ERROR(EINVAL)); zcp_alloc_arg_t allocargs = { .aa_must_succeed = B_TRUE, .aa_alloc_remaining = (int64_t)memlimit, .aa_alloc_limit = (int64_t)memlimit, }; /* * Creates a Lua state with a memory allocator that uses KM_SLEEP. * This should never fail. */ state = lua_newstate(zcp_lua_alloc, &allocargs); VERIFY(state != NULL); (void) lua_atpanic(state, zcp_panic_cb); /* * Load core Lua libraries we want access to. */ VERIFY3U(1, ==, luaopen_base(state)); lua_pop(state, 1); VERIFY3U(1, ==, luaopen_coroutine(state)); lua_setglobal(state, LUA_COLIBNAME); VERIFY0(lua_gettop(state)); VERIFY3U(1, ==, luaopen_string(state)); lua_setglobal(state, LUA_STRLIBNAME); VERIFY0(lua_gettop(state)); VERIFY3U(1, ==, luaopen_table(state)); lua_setglobal(state, LUA_TABLIBNAME); VERIFY0(lua_gettop(state)); /* * Load globally visible variables such as errno aliases. */ zcp_load_globals(state); VERIFY0(lua_gettop(state)); /* * Load ZFS-specific modules. */ lua_newtable(state); VERIFY3U(1, ==, zcp_load_list_lib(state)); lua_setfield(state, -2, "list"); VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_FALSE)); lua_setfield(state, -2, "check"); VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_TRUE)); lua_setfield(state, -2, "sync"); VERIFY3U(1, ==, zcp_load_get_lib(state)); lua_pushcclosure(state, zcp_debug_info.func, 0); lua_setfield(state, -2, zcp_debug_info.name); lua_pushcclosure(state, zcp_exists_info.func, 0); lua_setfield(state, -2, zcp_exists_info.name); lua_setglobal(state, "zfs"); VERIFY0(lua_gettop(state)); /* * Push the error-callback that calculates Lua stack traces on * unexpected failures. */ lua_pushcfunction(state, zcp_error_handler); VERIFY3U(1, ==, lua_gettop(state)); /* * Load the actual script as a function onto the stack as text ("t"). * The only valid error condition is a syntax error in the script. * ERRMEM should not be possible because our allocator is using * KM_SLEEP. ERRGCMM should not be possible because we have not added * any objects with __gc metamethods to the interpreter that could * fail. */ err = luaL_loadbufferx(state, program, strlen(program), "channel program", "t"); if (err == LUA_ERRSYNTAX) { fnvlist_add_string(outnvl, ZCP_RET_ERROR, lua_tostring(state, -1)); lua_close(state); return (SET_ERROR(EINVAL)); } VERIFY0(err); VERIFY3U(2, ==, lua_gettop(state)); /* * Convert the input nvlist to a Lua object and put it on top of the * stack. */ char errmsg[128]; err = zcp_nvpair_value_to_lua(state, nvarg, errmsg, sizeof (errmsg)); if (err != 0) { fnvlist_add_string(outnvl, ZCP_RET_ERROR, errmsg); lua_close(state); return (SET_ERROR(EINVAL)); } VERIFY3U(3, ==, lua_gettop(state)); runinfo.zri_state = state; runinfo.zri_allocargs = &allocargs; runinfo.zri_outnvl = outnvl; runinfo.zri_result = 0; runinfo.zri_cred = CRED(); runinfo.zri_proc = curproc; runinfo.zri_timed_out = B_FALSE; runinfo.zri_canceled = B_FALSE; runinfo.zri_sync = sync; runinfo.zri_space_used = 0; runinfo.zri_curinstrs = 0; runinfo.zri_maxinstrs = instrlimit; runinfo.zri_new_zvols = fnvlist_alloc(); if (sync) { err = dsl_sync_task_sig(poolname, NULL, zcp_eval_sync, zcp_eval_sig, &runinfo, 0, ZFS_SPACE_CHECK_ZCP_EVAL); if (err != 0) zcp_pool_error(&runinfo, poolname, err); } else { zcp_eval_open(&runinfo, poolname); } lua_close(state); /* * Create device minor nodes for any new zvols. */ for (nvpair_t *pair = nvlist_next_nvpair(runinfo.zri_new_zvols, NULL); pair != NULL; pair = nvlist_next_nvpair(runinfo.zri_new_zvols, pair)) { zvol_create_minor(nvpair_name(pair)); } fnvlist_free(runinfo.zri_new_zvols); return (runinfo.zri_result); } /* * Retrieve metadata about the currently running channel program. */ zcp_run_info_t * zcp_run_info(lua_State *state) { zcp_run_info_t *ri; lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY); ri = lua_touserdata(state, -1); lua_pop(state, 1); return (ri); } /* * Argument Parsing * ================ * * The Lua language allows methods to be called with any number * of arguments of any type. When calling back into ZFS we need to sanitize * arguments from channel programs to make sure unexpected arguments or * arguments of the wrong type result in clear error messages. To do this * in a uniform way all callbacks from channel programs should use the * zcp_parse_args() function to interpret inputs. * * Positional vs Keyword Arguments * =============================== * * Every callback function takes a fixed set of required positional arguments * and optional keyword arguments. For example, the destroy function takes * a single positional string argument (the name of the dataset to destroy) * and an optional "defer" keyword boolean argument. When calling lua functions * with parentheses, only positional arguments can be used: * * zfs.sync.snapshot("rpool@snap") * * To use keyword arguments functions should be called with a single argument * that is a lua table containing mappings of integer -> positional arguments * and string -> keyword arguments: * * zfs.sync.snapshot({1="rpool@snap", defer=true}) * * The lua language allows curly braces to be used in place of parenthesis as * syntactic sugar for this calling convention: * * zfs.sync.snapshot{"rpool@snap", defer=true} */ /* * Throw an error and print the given arguments. If there are too many * arguments to fit in the output buffer, only the error format string is * output. */ static void zcp_args_error(lua_State *state, const char *fname, const zcp_arg_t *pargs, const zcp_arg_t *kwargs, const char *fmt, ...) { int i; char errmsg[512]; size_t len = sizeof (errmsg); size_t msglen = 0; va_list argp; va_start(argp, fmt); VERIFY3U(len, >, vsnprintf(errmsg, len, fmt, argp)); va_end(argp); /* * Calculate the total length of the final string, including extra * formatting characters. If the argument dump would be too large, * only print the error string. */ msglen = strlen(errmsg); msglen += strlen(fname) + 4; /* : + {} + null terminator */ for (i = 0; pargs[i].za_name != NULL; i++) { msglen += strlen(pargs[i].za_name); msglen += strlen(lua_typename(state, pargs[i].za_lua_type)); if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL) msglen += 5; /* < + ( + )> + , */ else msglen += 4; /* < + ( + )> */ } for (i = 0; kwargs[i].za_name != NULL; i++) { msglen += strlen(kwargs[i].za_name); msglen += strlen(lua_typename(state, kwargs[i].za_lua_type)); if (kwargs[i + 1].za_name != NULL) msglen += 4; /* =( + ) + , */ else msglen += 3; /* =( + ) */ } if (msglen >= len) (void) luaL_error(state, errmsg); VERIFY3U(len, >, strlcat(errmsg, ": ", len)); VERIFY3U(len, >, strlcat(errmsg, fname, len)); VERIFY3U(len, >, strlcat(errmsg, "{", len)); for (i = 0; pargs[i].za_name != NULL; i++) { VERIFY3U(len, >, strlcat(errmsg, "<", len)); VERIFY3U(len, >, strlcat(errmsg, pargs[i].za_name, len)); VERIFY3U(len, >, strlcat(errmsg, "(", len)); VERIFY3U(len, >, strlcat(errmsg, lua_typename(state, pargs[i].za_lua_type), len)); VERIFY3U(len, >, strlcat(errmsg, ")>", len)); if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL) { VERIFY3U(len, >, strlcat(errmsg, ", ", len)); } } for (i = 0; kwargs[i].za_name != NULL; i++) { VERIFY3U(len, >, strlcat(errmsg, kwargs[i].za_name, len)); VERIFY3U(len, >, strlcat(errmsg, "=(", len)); VERIFY3U(len, >, strlcat(errmsg, lua_typename(state, kwargs[i].za_lua_type), len)); VERIFY3U(len, >, strlcat(errmsg, ")", len)); if (kwargs[i + 1].za_name != NULL) { VERIFY3U(len, >, strlcat(errmsg, ", ", len)); } } VERIFY3U(len, >, strlcat(errmsg, "}", len)); (void) luaL_error(state, errmsg); panic("unreachable code"); } static void zcp_parse_table_args(lua_State *state, const char *fname, const zcp_arg_t *pargs, const zcp_arg_t *kwargs) { int i; int type; for (i = 0; pargs[i].za_name != NULL; i++) { /* * Check the table for this positional argument, leaving it * on the top of the stack once we finish validating it. */ lua_pushinteger(state, i + 1); lua_gettable(state, 1); type = lua_type(state, -1); if (type == LUA_TNIL) { zcp_args_error(state, fname, pargs, kwargs, "too few arguments"); panic("unreachable code"); } else if (type != pargs[i].za_lua_type) { zcp_args_error(state, fname, pargs, kwargs, "arg %d wrong type (is '%s', expected '%s')", i + 1, lua_typename(state, type), lua_typename(state, pargs[i].za_lua_type)); panic("unreachable code"); } /* * Remove the positional argument from the table. */ lua_pushinteger(state, i + 1); lua_pushnil(state); lua_settable(state, 1); } for (i = 0; kwargs[i].za_name != NULL; i++) { /* * Check the table for this keyword argument, which may be * nil if it was omitted. Leave the value on the top of * the stack after validating it. */ lua_getfield(state, 1, kwargs[i].za_name); type = lua_type(state, -1); if (type != LUA_TNIL && type != kwargs[i].za_lua_type) { zcp_args_error(state, fname, pargs, kwargs, "kwarg '%s' wrong type (is '%s', expected '%s')", kwargs[i].za_name, lua_typename(state, type), lua_typename(state, kwargs[i].za_lua_type)); panic("unreachable code"); } /* * Remove the keyword argument from the table. */ lua_pushnil(state); lua_setfield(state, 1, kwargs[i].za_name); } /* * Any entries remaining in the table are invalid inputs, print * an error message based on what the entry is. */ lua_pushnil(state); if (lua_next(state, 1)) { if (lua_isnumber(state, -2) && lua_tointeger(state, -2) > 0) { zcp_args_error(state, fname, pargs, kwargs, "too many positional arguments"); } else if (lua_isstring(state, -2)) { zcp_args_error(state, fname, pargs, kwargs, "invalid kwarg '%s'", lua_tostring(state, -2)); } else { zcp_args_error(state, fname, pargs, kwargs, "kwarg keys must be strings"); } panic("unreachable code"); } lua_remove(state, 1); } static void zcp_parse_pos_args(lua_State *state, const char *fname, const zcp_arg_t *pargs, const zcp_arg_t *kwargs) { int i; int type; for (i = 0; pargs[i].za_name != NULL; i++) { type = lua_type(state, i + 1); if (type == LUA_TNONE) { zcp_args_error(state, fname, pargs, kwargs, "too few arguments"); panic("unreachable code"); } else if (type != pargs[i].za_lua_type) { zcp_args_error(state, fname, pargs, kwargs, "arg %d wrong type (is '%s', expected '%s')", i + 1, lua_typename(state, type), lua_typename(state, pargs[i].za_lua_type)); panic("unreachable code"); } } if (lua_gettop(state) != i) { zcp_args_error(state, fname, pargs, kwargs, "too many positional arguments"); panic("unreachable code"); } for (i = 0; kwargs[i].za_name != NULL; i++) { lua_pushnil(state); } } /* * Checks the current Lua stack against an expected set of positional and * keyword arguments. If the stack does not match the expected arguments * aborts the current channel program with a useful error message, otherwise * it re-arranges the stack so that it contains the positional arguments * followed by the keyword argument values in declaration order. Any missing * keyword argument will be represented by a nil value on the stack. * * If the stack contains exactly one argument of type LUA_TTABLE the curly * braces calling convention is assumed, otherwise the stack is parsed for * positional arguments only. * * This function should be used by every function callback. It should be called * before the callback manipulates the Lua stack as it assumes the stack * represents the function arguments. */ void zcp_parse_args(lua_State *state, const char *fname, const zcp_arg_t *pargs, const zcp_arg_t *kwargs) { if (lua_gettop(state) == 1 && lua_istable(state, 1)) { zcp_parse_table_args(state, fname, pargs, kwargs); } else { zcp_parse_pos_args(state, fname, pargs, kwargs); } } ZFS_MODULE_PARAM(zfs_lua, zfs_lua_, max_instrlimit, U64, ZMOD_RW, "Max instruction limit that can be specified for a channel program"); ZFS_MODULE_PARAM(zfs_lua, zfs_lua_, max_memlimit, U64, ZMOD_RW, "Max memory limit that can be specified for a channel program");