/* Unix SMB/CIFS implementation. generic byte range locking code - tdb backend Copyright (C) Andrew Tridgell 1992-2006 Copyright (C) Jeremy Allison 1992-2000 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/>. */ /* This module implements a tdb based byte range locking service, replacing the fcntl() based byte range locking previously used. This allows us to provide the same semantics as NT */ #include "includes.h" #include "system/filesys.h" #include "../tdb/include/tdb.h" #include "messaging/messaging.h" #include "lib/dbwrap/dbwrap.h" #include "lib/messaging/irpc.h" #include "libcli/libcli.h" #include "cluster/cluster.h" #include "ntvfs/common/brlock.h" #include "ntvfs/ntvfs.h" #include "param/param.h" /* in this module a "DATA_BLOB *file_key" is a blob that uniquely identifies a file. For a local posix filesystem this will usually be a combination of the device and inode numbers of the file, but it can be anything that uniquely idetifies a file for locking purposes, as long as it is applied consistently. */ /* this struct is typicaly attached to tcon */ struct brl_context { struct db_context *db; struct server_id server; struct messaging_context *messaging_ctx; }; /* the lock context contains the elements that define whether one lock is the same as another lock */ struct lock_context { struct server_id server; uint32_t smbpid; struct brl_context *ctx; }; /* The data in brlock records is an unsorted linear array of these records. It is unnecessary to store the count as tdb provides the size of the record */ struct lock_struct { struct lock_context context; struct ntvfs_handle *ntvfs; uint64_t start; uint64_t size; enum brl_type lock_type; void *notify_ptr; }; /* this struct is attached to on oprn file handle */ struct brl_handle { DATA_BLOB key; struct ntvfs_handle *ntvfs; struct lock_struct last_lock; }; /* Open up the brlock.tdb database. Close it down using talloc_free(). We need the messaging_ctx to allow for pending lock notifications. */ static struct brl_context *brl_tdb_init(TALLOC_CTX *mem_ctx, struct server_id server, struct loadparm_context *lp_ctx, struct messaging_context *messaging_ctx) { struct brl_context *brl; brl = talloc(mem_ctx, struct brl_context); if (brl == NULL) { return NULL; } brl->db = db_tmp_open(brl, lp_ctx, "brlock.tdb", TDB_DEFAULT); if (brl->db == NULL) { talloc_free(brl); return NULL; } brl->server = server; brl->messaging_ctx = messaging_ctx; return brl; } static struct brl_handle *brl_tdb_create_handle(TALLOC_CTX *mem_ctx, struct ntvfs_handle *ntvfs, DATA_BLOB *file_key) { struct brl_handle *brlh; brlh = talloc(mem_ctx, struct brl_handle); if (brlh == NULL) { return NULL; } brlh->key = *file_key; brlh->ntvfs = ntvfs; ZERO_STRUCT(brlh->last_lock); return brlh; } /* see if two locking contexts are equal */ static bool brl_tdb_same_context(struct lock_context *ctx1, struct lock_context *ctx2) { return (cluster_id_equal(&ctx1->server, &ctx2->server) && ctx1->smbpid == ctx2->smbpid && ctx1->ctx == ctx2->ctx); } /* see if lck1 and lck2 overlap lck1 is the existing lock. lck2 is the new lock we are looking at adding */ static bool brl_tdb_overlap(struct lock_struct *lck1, struct lock_struct *lck2) { /* this extra check is not redundent - it copes with locks that go beyond the end of 64 bit file space */ if (lck1->size != 0 && lck1->start == lck2->start && lck1->size == lck2->size) { return true; } if (lck1->start >= (lck2->start+lck2->size) || lck2->start >= (lck1->start+lck1->size)) { return false; } /* we have a conflict. Now check to see if lck1 really still * exists, which involves checking if the process still * exists. We leave this test to last as its the most * expensive test, especially when we are clustered */ /* TODO: need to do this via a server_id_exists() call, which * hasn't been written yet. When clustered this will need to * call into ctdb */ return true; } /* See if lock2 can be added when lock1 is in place. */ static bool brl_tdb_conflict(struct lock_struct *lck1, struct lock_struct *lck2) { /* pending locks don't conflict with anything */ if (lck1->lock_type >= PENDING_READ_LOCK || lck2->lock_type >= PENDING_READ_LOCK) { return false; } if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) { return false; } if (brl_tdb_same_context(&lck1->context, &lck2->context) && lck2->lock_type == READ_LOCK && lck1->ntvfs == lck2->ntvfs) { return false; } return brl_tdb_overlap(lck1, lck2); } /* Check to see if this lock conflicts, but ignore our own locks on the same fnum only. */ static bool brl_tdb_conflict_other(struct lock_struct *lck1, struct lock_struct *lck2) { /* pending locks don't conflict with anything */ if (lck1->lock_type >= PENDING_READ_LOCK || lck2->lock_type >= PENDING_READ_LOCK) { return false; } if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) return false; /* * note that incoming write calls conflict with existing READ * locks even if the context is the same. JRA. See LOCKTEST7 * in smbtorture. */ if (brl_tdb_same_context(&lck1->context, &lck2->context) && lck1->ntvfs == lck2->ntvfs && (lck2->lock_type == READ_LOCK || lck1->lock_type == WRITE_LOCK)) { return false; } return brl_tdb_overlap(lck1, lck2); } /* amazingly enough, w2k3 "remembers" whether the last lock failure is the same as this one and changes its error code. I wonder if any app depends on this? */ static NTSTATUS brl_tdb_lock_failed(struct brl_handle *brlh, struct lock_struct *lock) { /* * this function is only called for non pending lock! */ /* in SMB2 mode always return NT_STATUS_LOCK_NOT_GRANTED! */ if (lock->ntvfs->ctx->protocol == PROTOCOL_SMB2) { return NT_STATUS_LOCK_NOT_GRANTED; } /* * if the notify_ptr is non NULL, * it means that we're at the end of a pending lock * and the real lock is requested after the timout went by * In this case we need to remember the last_lock and always * give FILE_LOCK_CONFLICT */ if (lock->notify_ptr) { brlh->last_lock = *lock; return NT_STATUS_FILE_LOCK_CONFLICT; } /* * amazing the little things you learn with a test * suite. Locks beyond this offset (as a 64 bit * number!) always generate the conflict error code, * unless the top bit is set */ if (lock->start >= 0xEF000000 && (lock->start >> 63) == 0) { brlh->last_lock = *lock; return NT_STATUS_FILE_LOCK_CONFLICT; } /* * if the current lock matches the last failed lock on the file handle * and starts at the same offset, then FILE_LOCK_CONFLICT should be returned */ if (cluster_id_equal(&lock->context.server, &brlh->last_lock.context.server) && lock->context.ctx == brlh->last_lock.context.ctx && lock->ntvfs == brlh->last_lock.ntvfs && lock->start == brlh->last_lock.start) { return NT_STATUS_FILE_LOCK_CONFLICT; } brlh->last_lock = *lock; return NT_STATUS_LOCK_NOT_GRANTED; } /* Lock a range of bytes. The lock_type can be a PENDING_*_LOCK, in which case a real lock is first tried, and if that fails then a pending lock is created. When the pending lock is triggered (by someone else closing an overlapping lock range) a messaging notification is sent, identified by the notify_ptr */ static NTSTATUS brl_tdb_lock(struct brl_context *brl, struct brl_handle *brlh, uint32_t smbpid, uint64_t start, uint64_t size, enum brl_type lock_type, void *notify_ptr) { TDB_DATA kbuf, dbuf; int count=0, i; struct lock_struct lock, *locks=NULL; NTSTATUS status; struct db_record *rec = NULL; /* if this is a pending lock, then with the chainlock held we try to get the real lock. If we succeed then we don't need to make it pending. This prevents a possible race condition where the pending lock gets created after the lock that is preventing the real lock gets removed */ if (lock_type >= PENDING_READ_LOCK) { enum brl_type rw = (lock_type==PENDING_READ_LOCK? READ_LOCK : WRITE_LOCK); /* here we need to force that the last_lock isn't overwritten */ lock = brlh->last_lock; status = brl_tdb_lock(brl, brlh, smbpid, start, size, rw, NULL); brlh->last_lock = lock; if (NT_STATUS_IS_OK(status)) { return NT_STATUS_OK; } } kbuf.dptr = brlh->key.data; kbuf.dsize = brlh->key.length; rec = brl->db->fetch_locked(brl->db, brl, kbuf); if (rec == NULL) { return NT_STATUS_INTERNAL_DB_CORRUPTION; } dbuf = rec->value; lock.context.smbpid = smbpid; lock.context.server = brl->server; lock.context.ctx = brl; lock.ntvfs = brlh->ntvfs; lock.context.ctx = brl; lock.start = start; lock.size = size; lock.lock_type = lock_type; lock.notify_ptr = notify_ptr; if (dbuf.dptr) { /* there are existing locks - make sure they don't conflict */ locks = (struct lock_struct *)dbuf.dptr; count = dbuf.dsize / sizeof(*locks); for (i=0; i<count; i++) { if (brl_tdb_conflict(&locks[i], &lock)) { status = brl_tdb_lock_failed(brlh, &lock); goto fail; } } } /* no conflicts - add it to the list of locks */ locks = talloc_realloc(rec, locks, struct lock_struct, count+1); if (!locks) { status = NT_STATUS_NO_MEMORY; goto fail; } else { dbuf.dptr = (uint8_t *)locks; } locks[count] = lock; dbuf.dsize += sizeof(lock); status = rec->store(rec, dbuf, TDB_REPLACE); if (!NT_STATUS_IS_OK(status)) { goto fail; } talloc_free(rec); /* the caller needs to know if the real lock was granted. If we have reached here then it must be a pending lock that was granted, so tell them the lock failed */ if (lock_type >= PENDING_READ_LOCK) { return NT_STATUS_LOCK_NOT_GRANTED; } return NT_STATUS_OK; fail: talloc_free(rec); return status; } /* we are removing a lock that might be holding up a pending lock. Scan for pending locks that cover this range and if we find any then notify the server that it should retry the lock */ static void brl_tdb_notify_unlock(struct brl_context *brl, struct lock_struct *locks, int count, struct lock_struct *removed_lock) { int i, last_notice; /* the last_notice logic is to prevent stampeding on a lock range. It prevents us sending hundreds of notifies on the same range of bytes. It doesn't prevent all possible stampedes, but it does prevent the most common problem */ last_notice = -1; for (i=0;i<count;i++) { if (locks[i].lock_type >= PENDING_READ_LOCK && brl_tdb_overlap(&locks[i], removed_lock)) { if (last_notice != -1 && brl_tdb_overlap(&locks[i], &locks[last_notice])) { continue; } if (locks[i].lock_type == PENDING_WRITE_LOCK) { last_notice = i; } messaging_send_ptr(brl->messaging_ctx, locks[i].context.server, MSG_BRL_RETRY, locks[i].notify_ptr); } } } /* send notifications for all pending locks - the file is being closed by this user */ static void brl_tdb_notify_all(struct brl_context *brl, struct lock_struct *locks, int count) { int i; for (i=0;i<count;i++) { if (locks->lock_type >= PENDING_READ_LOCK) { brl_tdb_notify_unlock(brl, locks, count, &locks[i]); } } } /* Unlock a range of bytes. */ static NTSTATUS brl_tdb_unlock(struct brl_context *brl, struct brl_handle *brlh, uint32_t smbpid, uint64_t start, uint64_t size) { TDB_DATA kbuf, dbuf; int count, i; struct lock_struct *locks, *lock; struct lock_context context; NTSTATUS status; struct db_record *rec = NULL; kbuf.dptr = brlh->key.data; kbuf.dsize = brlh->key.length; rec = brl->db->fetch_locked(brl->db, brl, kbuf); if (rec == NULL) { return NT_STATUS_INTERNAL_DB_CORRUPTION; } if (!rec->value.dptr) { talloc_free(rec); return NT_STATUS_RANGE_NOT_LOCKED; } dbuf = rec->value; context.smbpid = smbpid; context.server = brl->server; context.ctx = brl; /* there are existing locks - find a match */ locks = (struct lock_struct *)dbuf.dptr; count = dbuf.dsize / sizeof(*locks); for (i=0; i<count; i++) { lock = &locks[i]; if (brl_tdb_same_context(&lock->context, &context) && lock->ntvfs == brlh->ntvfs && lock->start == start && lock->size == size && lock->lock_type == WRITE_LOCK) { break; } } if (i < count) goto found; for (i=0; i<count; i++) { lock = &locks[i]; if (brl_tdb_same_context(&lock->context, &context) && lock->ntvfs == brlh->ntvfs && lock->start == start && lock->size == size && lock->lock_type < PENDING_READ_LOCK) { break; } } found: if (i == count) { status = NT_STATUS_RANGE_NOT_LOCKED; } else if (count == 1) { status = rec->delete_rec(rec); } else { struct lock_struct removed_lock = *lock; if (i < count-1) { memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i)); } count--; /* send notifications for any relevant pending locks */ brl_tdb_notify_unlock(brl, locks, count, &removed_lock); dbuf.dsize = count * sizeof(*locks); status = rec->store(rec, dbuf, TDB_REPLACE); } talloc_free(rec); return status; } /* remove a pending lock. This is called when the caller has either given up trying to establish a lock or when they have succeeded in getting it. In either case they no longer need to be notified. */ static NTSTATUS brl_tdb_remove_pending(struct brl_context *brl, struct brl_handle *brlh, void *notify_ptr) { TDB_DATA kbuf, dbuf; int count, i; struct lock_struct *locks; NTSTATUS status; struct db_record *rec = NULL; kbuf.dptr = brlh->key.data; kbuf.dsize = brlh->key.length; rec = brl->db->fetch_locked(brl->db, brl, kbuf); if (rec == NULL) { return NT_STATUS_INTERNAL_DB_CORRUPTION; } dbuf = rec->value; /* there are existing locks - find a match */ locks = (struct lock_struct *)dbuf.dptr; count = dbuf.dsize / sizeof(*locks); status = NT_STATUS_RANGE_NOT_LOCKED; for (i=0; i<count; i++) { struct lock_struct *lock = &locks[i]; if (lock->lock_type >= PENDING_READ_LOCK && lock->notify_ptr == notify_ptr && cluster_id_equal(&lock->context.server, &brl->server)) { /* found it - delete it */ if (count == 1) { status = rec->delete_rec(rec); } else { if (i < count-1) { memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i)); } count--; dbuf.dsize = count * sizeof(*locks); status = rec->store(rec, dbuf, TDB_REPLACE); } break; } } talloc_free(rec); return status; } /* Test if we are allowed to perform IO on a region of an open file */ static NTSTATUS brl_tdb_locktest(struct brl_context *brl, struct brl_handle *brlh, uint32_t smbpid, uint64_t start, uint64_t size, enum brl_type lock_type) { TDB_DATA kbuf, dbuf; int count, i; struct lock_struct lock, *locks; NTSTATUS status; kbuf.dptr = brlh->key.data; kbuf.dsize = brlh->key.length; if (brl->db->fetch(brl->db, brl, kbuf, &dbuf) != 0) { return NT_STATUS_OK; } lock.context.smbpid = smbpid; lock.context.server = brl->server; lock.context.ctx = brl; lock.ntvfs = brlh->ntvfs; lock.start = start; lock.size = size; lock.lock_type = lock_type; /* there are existing locks - make sure they don't conflict */ locks = (struct lock_struct *)dbuf.dptr; count = dbuf.dsize / sizeof(*locks); status = NT_STATUS_OK; for (i=0; i<count; i++) { if (brl_tdb_conflict_other(&locks[i], &lock)) { status = NT_STATUS_FILE_LOCK_CONFLICT; break; } } talloc_free(dbuf.dptr); return status; } /* Remove any locks associated with a open file. */ static NTSTATUS brl_tdb_close(struct brl_context *brl, struct brl_handle *brlh) { TDB_DATA kbuf, dbuf; int count, i, dcount=0; struct lock_struct *locks; NTSTATUS status; struct db_record *rec = NULL; kbuf.dptr = brlh->key.data; kbuf.dsize = brlh->key.length; rec = brl->db->fetch_locked(brl->db, brl, kbuf); if (rec == NULL) { return NT_STATUS_INTERNAL_DB_CORRUPTION; } dbuf = rec->value; if (!dbuf.dptr) { talloc_free(rec); return NT_STATUS_OK; } /* there are existing locks - remove any for this fnum */ locks = (struct lock_struct *)dbuf.dptr; count = dbuf.dsize / sizeof(*locks); for (i=0; i<count; i++) { struct lock_struct *lock = &locks[i]; if (lock->context.ctx == brl && cluster_id_equal(&lock->context.server, &brl->server) && lock->ntvfs == brlh->ntvfs) { /* found it - delete it */ if (count > 1 && i < count-1) { memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i)); } count--; i--; dcount++; } } status = NT_STATUS_OK; if (count == 0) { status = rec->delete_rec(rec); } else if (dcount != 0) { /* tell all pending lock holders for this file that they have a chance now. This is a bit indiscriminant, but works OK */ brl_tdb_notify_all(brl, locks, count); dbuf.dsize = count * sizeof(*locks); status = rec->store(rec, dbuf, TDB_REPLACE); } talloc_free(rec); return status; } static const struct brlock_ops brlock_tdb_ops = { .brl_init = brl_tdb_init, .brl_create_handle = brl_tdb_create_handle, .brl_lock = brl_tdb_lock, .brl_unlock = brl_tdb_unlock, .brl_remove_pending = brl_tdb_remove_pending, .brl_locktest = brl_tdb_locktest, .brl_close = brl_tdb_close }; void brl_tdb_init_ops(void) { brl_set_ops(&brlock_tdb_ops); }