/* Unix SMB/CIFS implementation. Samba internal messaging functions Copyright (C) 2007 by Volker Lendecke This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ /** @defgroup messages Internal messaging framework @{ @file messages.c @brief Module for internal messaging between Samba daemons. The idea is that if a part of Samba wants to do communication with another Samba process then it will do a message_register() of a dispatch function, and use message_send_pid() to send messages to that process. The dispatch function is given the pid of the sender, and it can use that to reply by message_send_pid(). See ping_message() for a simple example. @caution Dispatch functions must be able to cope with incoming messages on an *odd* byte boundary. This system doesn't have any inherent size limitations but is not very efficient for large messages or when messages are sent in very quick succession. */ #include "includes.h" #include "librpc/gen_ndr/messaging.h" #include "librpc/gen_ndr/ndr_messaging.h" static sig_atomic_t received_signal; static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx, struct server_id pid, int msg_type, const DATA_BLOB *data, struct messaging_backend *backend); /**************************************************************************** Notifications come in as signals. ****************************************************************************/ static void sig_usr1(void) { received_signal = 1; sys_select_signal(SIGUSR1); } static int messaging_tdb_destructor(struct messaging_backend *tdb_ctx) { TDB_CONTEXT *tdb = (TDB_CONTEXT *)tdb_ctx->private_data; tdb_close(tdb); return 0; } /**************************************************************************** Initialise the messaging functions. ****************************************************************************/ NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx, TALLOC_CTX *mem_ctx, struct messaging_backend **presult) { struct messaging_backend *result; TDB_CONTEXT *tdb; if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) { DEBUG(0, ("talloc failed\n")); return NT_STATUS_NO_MEMORY; } tdb = tdb_open_log(lock_path("messages.tdb"), 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT, O_RDWR|O_CREAT,0600); if (!tdb) { NTSTATUS status = map_nt_error_from_unix(errno); DEBUG(0, ("ERROR: Failed to initialise messages database: " "%s\n", strerror(errno))); TALLOC_FREE(result); return status; } sec_init(); /* Activate the per-hashchain freelist */ tdb_set_max_dead(tdb, 5); CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1); result->private_data = (void *)tdb; result->send_fn = messaging_tdb_send; talloc_set_destructor(result, messaging_tdb_destructor); *presult = result; return NT_STATUS_OK; } /******************************************************************* Form a static tdb key from a pid. ******************************************************************/ static TDB_DATA message_key_pid(TALLOC_CTX *mem_ctx, struct server_id pid) { char *key; TDB_DATA kbuf; key = talloc_asprintf(talloc_tos(), "PID/%s", procid_str_static(&pid)); SMB_ASSERT(key != NULL); kbuf.dptr = (uint8 *)key; kbuf.dsize = strlen(key)+1; return kbuf; } /* Fetch the messaging array for a process */ static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb, TDB_DATA key, TALLOC_CTX *mem_ctx, struct messaging_array **presult) { struct messaging_array *result; TDB_DATA data; DATA_BLOB blob; enum ndr_err_code ndr_err; if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) { return NT_STATUS_NO_MEMORY; } data = tdb_fetch(msg_tdb, key); if (data.dptr == NULL) { *presult = result; return NT_STATUS_OK; } blob = data_blob_const(data.dptr, data.dsize); ndr_err = ndr_pull_struct_blob( &blob, result, result, (ndr_pull_flags_fn_t)ndr_pull_messaging_array); SAFE_FREE(data.dptr); if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) { TALLOC_FREE(result); return ndr_map_error2ntstatus(ndr_err); } if (DEBUGLEVEL >= 10) { DEBUG(10, ("messaging_tdb_fetch:\n")); NDR_PRINT_DEBUG(messaging_array, result); } *presult = result; return NT_STATUS_OK; } /* Store a messaging array for a pid */ static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb, TDB_DATA key, struct messaging_array *array) { TDB_DATA data; DATA_BLOB blob; enum ndr_err_code ndr_err; TALLOC_CTX *mem_ctx; int ret; if (array->num_messages == 0) { tdb_delete(msg_tdb, key); return NT_STATUS_OK; } if (!(mem_ctx = talloc_new(array))) { return NT_STATUS_NO_MEMORY; } ndr_err = ndr_push_struct_blob( &blob, mem_ctx, array, (ndr_push_flags_fn_t)ndr_push_messaging_array); if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) { talloc_free(mem_ctx); return ndr_map_error2ntstatus(ndr_err); } if (DEBUGLEVEL >= 10) { DEBUG(10, ("messaging_tdb_store:\n")); NDR_PRINT_DEBUG(messaging_array, array); } data.dptr = blob.data; data.dsize = blob.length; ret = tdb_store(msg_tdb, key, data, TDB_REPLACE); TALLOC_FREE(mem_ctx); return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION; } /**************************************************************************** Notify a process that it has a message. If the process doesn't exist then delete its record in the database. ****************************************************************************/ static NTSTATUS message_notify(struct server_id procid) { pid_t pid = procid.pid; int ret; uid_t euid = geteuid(); /* * Doing kill with a non-positive pid causes messages to be * sent to places we don't want. */ SMB_ASSERT(pid > 0); if (euid != 0) { /* If we're not root become so to send the message. */ save_re_uid(); set_effective_uid(0); } ret = kill(pid, SIGUSR1); if (euid != 0) { /* Go back to who we were. */ int saved_errno = errno; restore_re_uid_fromroot(); errno = saved_errno; } if (ret == 0) { return NT_STATUS_OK; } /* * Something has gone wrong */ DEBUG(2,("message to process %d failed - %s\n", (int)pid, strerror(errno))); /* * No call to map_nt_error_from_unix -- don't want to link in * errormap.o into lots of utils. */ if (errno == ESRCH) return NT_STATUS_INVALID_HANDLE; if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER; if (errno == EPERM) return NT_STATUS_ACCESS_DENIED; return NT_STATUS_UNSUCCESSFUL; } /**************************************************************************** Send a message to a particular pid. ****************************************************************************/ static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx, struct server_id pid, int msg_type, const DATA_BLOB *data, struct messaging_backend *backend) { struct messaging_array *msg_array; struct messaging_rec *rec; NTSTATUS status; TDB_DATA key; TDB_CONTEXT *tdb = (TDB_CONTEXT *)backend->private_data; TALLOC_CTX *frame = talloc_stackframe(); /* NULL pointer means implicit length zero. */ if (!data->data) { SMB_ASSERT(data->length == 0); } /* * Doing kill with a non-positive pid causes messages to be * sent to places we don't want. */ SMB_ASSERT(procid_to_pid(&pid) > 0); key = message_key_pid(frame, pid); if (tdb_chainlock(tdb, key) == -1) { TALLOC_FREE(frame); return NT_STATUS_LOCK_NOT_GRANTED; } status = messaging_tdb_fetch(tdb, key, talloc_tos(), &msg_array); if (!NT_STATUS_IS_OK(status)) { goto done; } if ((msg_type & MSG_FLAG_LOWPRIORITY) && (msg_array->num_messages > 1000)) { DEBUG(5, ("Dropping message for PID %s\n", procid_str_static(&pid))); status = NT_STATUS_INSUFFICIENT_RESOURCES; goto done; } if (!(rec = TALLOC_REALLOC_ARRAY(talloc_tos(), msg_array->messages, struct messaging_rec, msg_array->num_messages+1))) { status = NT_STATUS_NO_MEMORY; goto done; } rec[msg_array->num_messages].msg_version = MESSAGE_VERSION; rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK; rec[msg_array->num_messages].dest = pid; rec[msg_array->num_messages].src = procid_self(); rec[msg_array->num_messages].buf = *data; msg_array->messages = rec; msg_array->num_messages += 1; status = messaging_tdb_store(tdb, key, msg_array); if (!NT_STATUS_IS_OK(status)) { goto done; } status = message_notify(pid); if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) { DEBUG(2, ("pid %s doesn't exist - deleting messages record\n", procid_str_static(&pid))); tdb_delete(tdb, message_key_pid(talloc_tos(), pid)); } done: tdb_chainunlock(tdb, key); TALLOC_FREE(frame); return status; } /**************************************************************************** Retrieve all messages for the current process. ****************************************************************************/ static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb, TALLOC_CTX *mem_ctx, struct messaging_array **presult) { struct messaging_array *result; TDB_DATA key = message_key_pid(mem_ctx, procid_self()); NTSTATUS status; if (tdb_chainlock(msg_tdb, key) == -1) { TALLOC_FREE(key.dptr); return NT_STATUS_LOCK_NOT_GRANTED; } status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result); /* * We delete the record here, tdb_set_max_dead keeps it around */ tdb_delete(msg_tdb, key); tdb_chainunlock(msg_tdb, key); if (NT_STATUS_IS_OK(status)) { *presult = result; } TALLOC_FREE(key.dptr); return status; } /**************************************************************************** Receive and dispatch any messages pending for this process. JRA changed Dec 13 2006. Only one message handler now permitted per type. *NOTE*: Dispatch functions must be able to cope with incoming messages on an *odd* byte boundary. ****************************************************************************/ void message_dispatch(struct messaging_context *msg_ctx) { struct messaging_array *msg_array = NULL; TDB_CONTEXT *tdb = (TDB_CONTEXT *)(msg_ctx->local->private_data); uint32 i; if (!received_signal) return; DEBUG(10, ("message_dispatch: received_signal = %d\n", received_signal)); received_signal = 0; if (!NT_STATUS_IS_OK(retrieve_all_messages(tdb, NULL, &msg_array))) { return; } for (i=0; i<msg_array->num_messages; i++) { messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]); } TALLOC_FREE(msg_array); } /** @} **/