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Diffstat (limited to '')
-rw-r--r-- | source4/ntvfs/common/brlock_tdb.c | 775 |
1 files changed, 775 insertions, 0 deletions
diff --git a/source4/ntvfs/common/brlock_tdb.c b/source4/ntvfs/common/brlock_tdb.c new file mode 100644 index 0000000..c4cd76b --- /dev/null +++ b/source4/ntvfs/common/brlock_tdb.c @@ -0,0 +1,775 @@ +/* + 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 "messaging/messaging.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" +#include "dbwrap/dbwrap.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 identifies a file for locking purposes, as long + as it is applied consistently. +*/ + +/* this struct is typically attached to tcon */ +struct brl_context { + struct db_context *db; + struct server_id server; + struct imessaging_context *imessaging_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; +}; + +/* see if we have wrapped locks, which are no longer allowed (windows + * changed this in win7 */ +static bool brl_invalid_lock_range(uint64_t start, uint64_t size) +{ + return (size > 1 && (start + size < start)); +} + +/* + Open up the brlock.tdb database. Close it down using + talloc_free(). We need the imessaging_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 imessaging_context *imessaging_ctx) +{ + struct brl_context *brl; + + brl = talloc(mem_ctx, struct brl_context); + if (brl == NULL) { + return NULL; + } + + brl->db = cluster_db_tmp_open(brl, lp_ctx, "brlock", TDB_DEFAULT); + if (brl->db == NULL) { + talloc_free(brl); + return NULL; + } + + brl->server = server; + brl->imessaging_ctx = imessaging_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 redundant - 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_02) { + 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 timeout 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 *locked; + + kbuf.dptr = brlh->key.data; + kbuf.dsize = brlh->key.length; + + if (brl_invalid_lock_range(start, size)) { + return NT_STATUS_INVALID_LOCK_RANGE; + } + + locked = dbwrap_fetch_locked(brl->db, brl, kbuf); + if (!locked) { + return NT_STATUS_INTERNAL_DB_CORRUPTION; + } + + /* 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)) { + talloc_free(locked); + return NT_STATUS_OK; + } + } + + dbuf = dbwrap_record_get_value(locked); + + 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 */ + /* FIXME: a dbwrap_record_append() would help here! */ + locks = talloc_array(locked, struct lock_struct, count+1); + if (!locks) { + status = NT_STATUS_NO_MEMORY; + goto fail; + } + if (dbuf.dsize > 0) { + memcpy(locks, dbuf.dptr, dbuf.dsize); + } + locks[count] = lock; + + dbuf.dptr = (unsigned char *)locks; + dbuf.dsize += sizeof(lock); + + status = dbwrap_record_store(locked, dbuf, TDB_REPLACE); + if (!NT_STATUS_IS_OK(status)) { + goto fail; + } + + talloc_free(locked); + + /* 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(locked); + 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; + } + imessaging_send_ptr(brl->imessaging_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 = NULL; + struct lock_context context; + struct db_record *locked; + NTSTATUS status; + + kbuf.dptr = brlh->key.data; + kbuf.dsize = brlh->key.length; + + if (brl_invalid_lock_range(start, size)) { + return NT_STATUS_INVALID_LOCK_RANGE; + } + + locked = dbwrap_fetch_locked(brl->db, brl, kbuf); + if (!locked) { + return NT_STATUS_INTERNAL_DB_CORRUPTION; + } + dbuf = dbwrap_record_get_value(locked); + + 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) { + /* found it - delete it */ + if (count == 1) { + status = dbwrap_record_delete(locked); + if (!NT_STATUS_IS_OK(status)) { + goto fail; + } + } 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 = dbwrap_record_store(locked, dbuf, TDB_REPLACE); + if (!NT_STATUS_IS_OK(status)) { + goto fail; + } + } + + talloc_free(locked); + return NT_STATUS_OK; + } + + /* we didn't find it */ + status = NT_STATUS_RANGE_NOT_LOCKED; + + fail: + talloc_free(locked); + 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 *locked; + + kbuf.dptr = brlh->key.data; + kbuf.dsize = brlh->key.length; + + locked = dbwrap_fetch_locked(brl->db, brl, kbuf); + if (!locked) { + return NT_STATUS_INTERNAL_DB_CORRUPTION; + } + + dbuf = dbwrap_record_get_value(locked); + if (!dbuf.dptr) { + talloc_free(locked); + return NT_STATUS_RANGE_NOT_LOCKED; + } + + /* there are existing locks - find a match */ + 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->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 = dbwrap_record_delete(locked); + if (!NT_STATUS_IS_OK(status)) { + goto fail; + } + } else { + if (i < count-1) { + memmove(&locks[i], &locks[i+1], + sizeof(*locks)*((count-1) - i)); + } + count--; + dbuf.dsize = count * sizeof(*locks); + status = dbwrap_record_store(locked, dbuf, + TDB_REPLACE); + if (!NT_STATUS_IS_OK(status)) { + goto fail; + } + } + + talloc_free(locked); + return NT_STATUS_OK; + } + } + + /* we didn't find it */ + status = NT_STATUS_RANGE_NOT_LOCKED; + + fail: + talloc_free(locked); + 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_invalid_lock_range(start, size)) { + return NT_STATUS_INVALID_LOCK_RANGE; + } + + status = dbwrap_fetch(brl->db, brl, kbuf, &dbuf); + if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) { + return NT_STATUS_OK; + } else if (!NT_STATUS_IS_OK(status)) { + return status; + } + + 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); + + for (i=0; i<count; i++) { + if (brl_tdb_conflict_other(&locks[i], &lock)) { + talloc_free(dbuf.dptr); + return NT_STATUS_FILE_LOCK_CONFLICT; + } + } + + talloc_free(dbuf.dptr); + return NT_STATUS_OK; +} + + +/* + 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; + struct db_record *locked; + NTSTATUS status; + + kbuf.dptr = brlh->key.data; + kbuf.dsize = brlh->key.length; + + locked = dbwrap_fetch_locked(brl->db, brl, kbuf); + if (!locked) { + return NT_STATUS_INTERNAL_DB_CORRUPTION; + } + dbuf = dbwrap_record_get_value(locked); + if (!dbuf.dptr) { + talloc_free(locked); + 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 = dbwrap_record_delete(locked); + } 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 = dbwrap_record_store(locked, dbuf, TDB_REPLACE); + } + talloc_free(locked); + + return status; +} + +static NTSTATUS brl_tdb_count(struct brl_context *brl, struct brl_handle *brlh, + int *count) +{ + TDB_DATA kbuf, dbuf; + NTSTATUS status; + + kbuf.dptr = brlh->key.data; + kbuf.dsize = brlh->key.length; + *count = 0; + + status = dbwrap_fetch(brl->db, brl, kbuf, &dbuf); + if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) { + return NT_STATUS_OK; + } else if (!NT_STATUS_IS_OK(status)) { + return status; + } + *count = dbuf.dsize / sizeof(struct lock_struct); + + talloc_free(dbuf.dptr); + + return NT_STATUS_OK; +} + +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, + .brl_count = brl_tdb_count +}; + + +void brl_tdb_init_ops(void) +{ + brlock_set_ops(&brlock_tdb_ops); +} |