python: models: rename argument ldb to samdb

[samba.git] / source3 / smbd / blocking.c

/* 
   Unix SMB/CIFS implementation.
   Blocking Locking functions
   Copyright (C) Jeremy Allison 1998-2003

   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/>.
*/

#include "includes.h"
#include "locking/share_mode_lock.h"
#include "smbd/smbd.h"
#include "smbd/globals.h"
#include "messages.h"
#include "lib/util/tevent_ntstatus.h"
#include "lib/dbwrap/dbwrap_watch.h"
#include "librpc/gen_ndr/ndr_open_files.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

NTSTATUS smbd_do_locks_try(
        struct files_struct *fsp,
        uint16_t num_locks,
        struct smbd_lock_element *locks,
        uint16_t *blocker_idx,
        struct server_id *blocking_pid,
        uint64_t *blocking_smblctx)
{
        NTSTATUS status = NT_STATUS_OK;
        uint16_t i;

        for (i=0; i<num_locks; i++) {
                struct smbd_lock_element *e = &locks[i];

                status = do_lock(
                        fsp,
                        locks, /* req_mem_ctx */
                        &e->req_guid,
                        e->smblctx,
                        e->count,
                        e->offset,
                        e->brltype,
                        e->lock_flav,
                        blocking_pid,
                        blocking_smblctx);
                if (!NT_STATUS_IS_OK(status)) {
                        break;
                }
        }

        if (NT_STATUS_IS_OK(status)) {
                return NT_STATUS_OK;
        }

        *blocker_idx = i;

        /*
         * Undo the locks we successfully got
         */
        for (i = i-1; i != UINT16_MAX; i--) {
                struct smbd_lock_element *e = &locks[i];
                do_unlock(fsp,
                          e->smblctx,
                          e->count,
                          e->offset,
                          e->lock_flav);
        }

        return status;
}

static bool smbd_smb1_fsp_add_blocked_lock_req(
        struct files_struct *fsp, struct tevent_req *req)
{
        size_t num_reqs = talloc_array_length(fsp->blocked_smb1_lock_reqs);
        struct tevent_req **tmp = NULL;

        tmp = talloc_realloc(
                fsp,
                fsp->blocked_smb1_lock_reqs,
                struct tevent_req *,
                num_reqs+1);
        if (tmp == NULL) {
                return false;
        }
        fsp->blocked_smb1_lock_reqs = tmp;
        fsp->blocked_smb1_lock_reqs[num_reqs] = req;
        return true;
}

struct smbd_smb1_do_locks_state {
        struct tevent_context *ev;
        struct smb_request *smbreq;
        struct files_struct *fsp;
        uint32_t timeout;
        uint32_t polling_msecs;
        uint32_t retry_msecs;
        struct timeval endtime;
        bool large_offset;      /* required for correct cancel */
        uint16_t num_locks;
        struct smbd_lock_element *locks;
        uint16_t blocker;
        NTSTATUS deny_status;
};

static void smbd_smb1_do_locks_try(struct tevent_req *req);
static void smbd_smb1_do_locks_retry(struct tevent_req *subreq);
static void smbd_smb1_blocked_locks_cleanup(
        struct tevent_req *req, enum tevent_req_state req_state);
static NTSTATUS smbd_smb1_do_locks_check(
        struct files_struct *fsp,
        uint16_t num_locks,
        struct smbd_lock_element *locks,
        uint16_t *blocker_idx,
        struct server_id *blocking_pid,
        uint64_t *blocking_smblctx);

static void smbd_smb1_do_locks_setup_timeout(
        struct smbd_smb1_do_locks_state *state,
        const struct smbd_lock_element *blocker)
{
        struct files_struct *fsp = state->fsp;

        if (!timeval_is_zero(&state->endtime)) {
                /*
                 * already done
                 */
                return;
        }

        if ((state->timeout != 0) && (state->timeout != UINT32_MAX)) {
                /*
                 * Windows internal resolution for blocking locks
                 * seems to be about 200ms... Don't wait for less than
                 * that. JRA.
                 */
                state->timeout = MAX(state->timeout, lp_lock_spin_time());
        }

        if (state->timeout != 0) {
                goto set_endtime;
        }

        if (blocker == NULL) {
                goto set_endtime;
        }

        if ((blocker->offset >= 0xEF000000) &&
            ((blocker->offset >> 63) == 0)) {
                /*
                 * This must be an optimization of an ancient
                 * application bug...
                 */
                state->timeout = lp_lock_spin_time();
        }

        if (fsp->fsp_flags.lock_failure_seen &&
            (blocker->offset == fsp->lock_failure_offset)) {
                /*
                 * Delay repeated lock attempts on the same
                 * lock. Maybe a more advanced version of the
                 * above check?
                 */
                DBG_DEBUG("Delaying lock request due to previous "
                          "failure\n");
                state->timeout = lp_lock_spin_time();
        }

set_endtime:
        /*
         * Note state->timeout might still 0,
         * but that's ok, as we don't want to retry
         * in that case.
         */
        state->endtime = timeval_add(&state->smbreq->request_time,
                                     state->timeout / 1000,
                                     (state->timeout % 1000) * 1000);
}

static void smbd_smb1_do_locks_update_retry_msecs(
        struct smbd_smb1_do_locks_state *state)
{
        /*
         * The default lp_lock_spin_time() is 200ms,
         * we just use half of it to trigger the first retry.
         *
         * v_min is in the range of 0.001 to 10 secs
         * (0.1 secs by default)
         *
         * v_max is in the range of 0.01 to 100 secs
         * (1.0 secs by default)
         *
         * The typical steps are:
         * 0.1, 0.2, 0.3, 0.4, ... 1.0
         */
        uint32_t v_min = MAX(2, MIN(20000, lp_lock_spin_time()))/2;
        uint32_t v_max = 10 * v_min;

        if (state->retry_msecs >= v_max) {
                state->retry_msecs = v_max;
                return;
        }

        state->retry_msecs += v_min;
}

static void smbd_smb1_do_locks_update_polling_msecs(
        struct smbd_smb1_do_locks_state *state)
{
        /*
         * The default lp_lock_spin_time() is 200ms.
         *
         * v_min is in the range of 0.002 to 20 secs
         * (0.2 secs by default)
         *
         * v_max is in the range of 0.02 to 200 secs
         * (2.0 secs by default)
         *
         * The typical steps are:
         * 0.2, 0.4, 0.6, 0.8, ... 2.0
         */
        uint32_t v_min = MAX(2, MIN(20000, lp_lock_spin_time()));
        uint32_t v_max = 10 * v_min;

        if (state->polling_msecs >= v_max) {
                state->polling_msecs = v_max;
                return;
        }

        state->polling_msecs += v_min;
}

struct tevent_req *smbd_smb1_do_locks_send(
        TALLOC_CTX *mem_ctx,
        struct tevent_context *ev,
        struct smb_request **smbreq, /* talloc_move()d into our state */
        struct files_struct *fsp,
        uint32_t lock_timeout,
        bool large_offset,
        uint16_t num_locks,
        struct smbd_lock_element *locks)
{
        struct tevent_req *req = NULL;
        struct smbd_smb1_do_locks_state *state = NULL;
        bool ok;

        req = tevent_req_create(
                mem_ctx, &state, struct smbd_smb1_do_locks_state);
        if (req == NULL) {
                return NULL;
        }
        state->ev = ev;
        state->smbreq = talloc_move(state, smbreq);
        state->fsp = fsp;
        state->timeout = lock_timeout;
        state->large_offset = large_offset;
        state->num_locks = num_locks;
        state->locks = locks;
        state->deny_status = NT_STATUS_LOCK_NOT_GRANTED;

        DBG_DEBUG("state=%p, state->smbreq=%p\n", state, state->smbreq);

        if (num_locks == 0 || locks == NULL) {
                DBG_DEBUG("no locks\n");
                tevent_req_done(req);
                return tevent_req_post(req, ev);
        }

        if (state->locks[0].lock_flav == POSIX_LOCK) {
                /*
                 * SMB1 posix locks always use
                 * NT_STATUS_FILE_LOCK_CONFLICT.
                 */
                state->deny_status = NT_STATUS_FILE_LOCK_CONFLICT;
        }

        smbd_smb1_do_locks_try(req);
        if (!tevent_req_is_in_progress(req)) {
                return tevent_req_post(req, ev);
        }

        ok = smbd_smb1_fsp_add_blocked_lock_req(fsp, req);
        if (!ok) {
                tevent_req_oom(req);
                return tevent_req_post(req, ev);
        }
        tevent_req_set_cleanup_fn(req, smbd_smb1_blocked_locks_cleanup);
        return req;
}

static void smbd_smb1_blocked_locks_cleanup(
        struct tevent_req *req, enum tevent_req_state req_state)
{
        struct smbd_smb1_do_locks_state *state = tevent_req_data(
                req, struct smbd_smb1_do_locks_state);
        struct files_struct *fsp = state->fsp;
        struct tevent_req **blocked = fsp->blocked_smb1_lock_reqs;
        size_t num_blocked = talloc_array_length(blocked);
        size_t i;

        DBG_DEBUG("req=%p, state=%p, req_state=%d\n",
                  req,
                  state,
                  (int)req_state);

        if (req_state == TEVENT_REQ_RECEIVED) {
                DBG_DEBUG("already received\n");
                return;
        }

        for (i=0; i<num_blocked; i++) {
                if (blocked[i] == req) {
                        break;
                }
        }
        SMB_ASSERT(i<num_blocked);

        ARRAY_DEL_ELEMENT(blocked, i, num_blocked);

        fsp->blocked_smb1_lock_reqs = talloc_realloc(
                fsp, blocked, struct tevent_req *, num_blocked-1);
}

static NTSTATUS smbd_smb1_do_locks_check_blocked(
        uint16_t num_blocked,
        struct smbd_lock_element *blocked,
        uint16_t num_locks,
        struct smbd_lock_element *locks,
        uint16_t *blocker_idx,
        uint64_t *blocking_smblctx)
{
        uint16_t li;

        for (li=0; li < num_locks; li++) {
                struct smbd_lock_element *l = &locks[li];
                uint16_t bi;
                bool valid;

                valid = byte_range_valid(l->offset, l->count);
                if (!valid) {
                        return NT_STATUS_INVALID_LOCK_RANGE;
                }

                for (bi = 0; bi < num_blocked; bi++) {
                        struct smbd_lock_element *b = &blocked[li];
                        bool overlap;

                        /* Read locks never conflict. */
                        if (l->brltype == READ_LOCK && b->brltype == READ_LOCK) {
                                continue;
                        }

                        overlap = byte_range_overlap(l->offset,
                                                     l->count,
                                                     b->offset,
                                                     b->count);
                        if (!overlap) {
                                continue;
                        }

                        *blocker_idx = li;
                        *blocking_smblctx = b->smblctx;
                        return NT_STATUS_LOCK_NOT_GRANTED;
                }
        }

        return NT_STATUS_OK;
}

static NTSTATUS smbd_smb1_do_locks_check(
        struct files_struct *fsp,
        uint16_t num_locks,
        struct smbd_lock_element *locks,
        uint16_t *blocker_idx,
        struct server_id *blocking_pid,
        uint64_t *blocking_smblctx)
{
        struct tevent_req **blocked = fsp->blocked_smb1_lock_reqs;
        size_t num_blocked = talloc_array_length(blocked);
        NTSTATUS status;
        size_t bi;

        /*
         * We check the pending/blocked requests
         * from the oldest to the youngest request.
         *
         * Note due to the retry logic the current request
         * might already be in the list.
         */

        for (bi = 0; bi < num_blocked; bi++) {
                struct smbd_smb1_do_locks_state *blocked_state =
                        tevent_req_data(blocked[bi],
                        struct smbd_smb1_do_locks_state);

                if (blocked_state->locks == locks) {
                        SMB_ASSERT(blocked_state->num_locks == num_locks);

                        /*
                         * We found ourself...
                         */
                        break;
                }

                status = smbd_smb1_do_locks_check_blocked(
                                blocked_state->num_locks,
                                blocked_state->locks,
                                num_locks,
                                locks,
                                blocker_idx,
                                blocking_smblctx);
                if (!NT_STATUS_IS_OK(status)) {
                        *blocking_pid = messaging_server_id(
                                        fsp->conn->sconn->msg_ctx);
                        return status;
                }
        }

        status = smbd_do_locks_try(
                fsp,
                num_locks,
                locks,
                blocker_idx,
                blocking_pid,
                blocking_smblctx);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        return NT_STATUS_OK;
}

static void smbd_smb1_do_locks_try(struct tevent_req *req)
{
        struct smbd_smb1_do_locks_state *state = tevent_req_data(
                req, struct smbd_smb1_do_locks_state);
        struct files_struct *fsp = state->fsp;
        struct share_mode_lock *lck;
        struct timeval endtime = { 0 };
        struct server_id blocking_pid = { 0 };
        uint64_t blocking_smblctx = 0;
        struct tevent_req *subreq = NULL;
        NTSTATUS status;
        bool ok;
        bool expired;

        lck = get_existing_share_mode_lock(state, fsp->file_id);
        if (tevent_req_nomem(lck, req)) {
                DBG_DEBUG("Could not get share mode lock\n");
                return;
        }

        status = smbd_smb1_do_locks_check(
                fsp,
                state->num_locks,
                state->locks,
                &state->blocker,
                &blocking_pid,
                &blocking_smblctx);
        if (NT_STATUS_IS_OK(status)) {
                goto done;
        }
        if (NT_STATUS_EQUAL(status, NT_STATUS_RETRY)) {
                /*
                 * We got NT_STATUS_RETRY,
                 * we reset polling_msecs so that
                 * that the retries based on LOCK_NOT_GRANTED
                 * will later start with small intervals again.
                 */
                state->polling_msecs = 0;

                /*
                 * The backend wasn't able to decide yet.
                 * We need to wait even for non-blocking
                 * locks.
                 *
                 * The backend uses blocking_smblctx == UINT64_MAX
                 * to indicate that we should use retry timers.
                 *
                 * It uses blocking_smblctx == 0 to indicate
                 * it will use share_mode_wakeup_waiters()
                 * to wake us. Note that unrelated changes in
                 * locking.tdb may cause retries.
                 */

                if (blocking_smblctx != UINT64_MAX) {
                        SMB_ASSERT(blocking_smblctx == 0);
                        goto setup_retry;
                }

                smbd_smb1_do_locks_update_retry_msecs(state);

                DBG_DEBUG("Waiting for a backend decision. "
                          "Retry in %"PRIu32" msecs\n",
                          state->retry_msecs);

                /*
                 * We completely ignore state->endtime here
                 * we we'll wait for a backend decision forever.
                 * If the backend is smart enough to implement
                 * some NT_STATUS_RETRY logic, it has to
                 * switch to any other status after in order
                 * to avoid waiting forever.
                 */
                endtime = timeval_current_ofs_msec(state->retry_msecs);
                goto setup_retry;
        }
        if (!ERROR_WAS_LOCK_DENIED(status)) {
                goto done;
        }
        /*
         * We got LOCK_NOT_GRANTED, make sure
         * a following STATUS_RETRY will start
         * with short intervals again.
         */
        state->retry_msecs = 0;

        smbd_smb1_do_locks_setup_timeout(state, &state->locks[state->blocker]);
        DBG_DEBUG("timeout=%"PRIu32", blocking_smblctx=%"PRIu64"\n",
                  state->timeout,
                  blocking_smblctx);

        /*
         * The client specified timeout expired
         * avoid further retries.
         *
         * Otherwise keep waiting either waiting
         * for changes in locking.tdb or the polling
         * mode timers waiting for posix locks.
         *
         * If the endtime is not expired yet,
         * it means we'll retry after a timeout.
         * In that case we'll have to return
         * NT_STATUS_FILE_LOCK_CONFLICT
         * instead of NT_STATUS_LOCK_NOT_GRANTED.
         */
        expired = timeval_expired(&state->endtime);
        if (expired) {
                status = state->deny_status;
                goto done;
        }
        state->deny_status = NT_STATUS_FILE_LOCK_CONFLICT;

        endtime = state->endtime;

        if (blocking_smblctx == UINT64_MAX) {
                struct timeval tmp;

                smbd_smb1_do_locks_update_polling_msecs(state);

                DBG_DEBUG("Blocked on a posix lock. Retry in %"PRIu32" msecs\n",
                          state->polling_msecs);

                tmp = timeval_current_ofs_msec(state->polling_msecs);
                endtime = timeval_min(&endtime, &tmp);
        }

setup_retry:
        subreq = share_mode_watch_send(
                state, state->ev, lck, blocking_pid);
        if (tevent_req_nomem(subreq, req)) {
                goto done;
        }
        TALLOC_FREE(lck);
        tevent_req_set_callback(subreq, smbd_smb1_do_locks_retry, req);

        if (timeval_is_zero(&endtime)) {
                return;
        }

        ok = tevent_req_set_endtime(subreq, state->ev, endtime);
        if (!ok) {
                status = NT_STATUS_NO_MEMORY;
                goto done;
        }
        return;
done:
        TALLOC_FREE(lck);
        smbd_smb1_brl_finish_by_req(req, status);
}

static void smbd_smb1_do_locks_retry(struct tevent_req *subreq)
{
        struct tevent_req *req = tevent_req_callback_data(
                subreq, struct tevent_req);
        struct smbd_smb1_do_locks_state *state = tevent_req_data(
                req, struct smbd_smb1_do_locks_state);
        NTSTATUS status;
        bool ok;

        /*
         * Make sure we run as the user again
         */
        ok = change_to_user_and_service_by_fsp(state->fsp);
        if (!ok) {
                tevent_req_nterror(req, NT_STATUS_ACCESS_DENIED);
                return;
        }

        status = share_mode_watch_recv(subreq, NULL, NULL);
        TALLOC_FREE(subreq);

        DBG_DEBUG("share_mode_watch_recv returned %s\n",
                  nt_errstr(status));

        /*
         * We ignore any errors here, it's most likely
         * we just get NT_STATUS_OK or NT_STATUS_IO_TIMEOUT.
         *
         * In any case we can just give it a retry.
         */

        smbd_smb1_do_locks_try(req);
}

NTSTATUS smbd_smb1_do_locks_recv(struct tevent_req *req)
{
        struct smbd_smb1_do_locks_state *state = tevent_req_data(
                req, struct smbd_smb1_do_locks_state);
        NTSTATUS status = NT_STATUS_OK;
        bool err;

        err = tevent_req_is_nterror(req, &status);

        DBG_DEBUG("err=%d, status=%s\n", (int)err, nt_errstr(status));

        if (tevent_req_is_nterror(req, &status)) {
                struct files_struct *fsp = state->fsp;
                struct smbd_lock_element *blocker =
                        &state->locks[state->blocker];

                DBG_DEBUG("Setting lock_failure_offset=%"PRIu64"\n",
                          blocker->offset);

                fsp->fsp_flags.lock_failure_seen = true;
                fsp->lock_failure_offset = blocker->offset;
                return status;
        }

        tevent_req_received(req);

        return NT_STATUS_OK;
}

bool smbd_smb1_do_locks_extract_smbreq(
        struct tevent_req *req,
        TALLOC_CTX *mem_ctx,
        struct smb_request **psmbreq)
{
        struct smbd_smb1_do_locks_state *state = tevent_req_data(
                req, struct smbd_smb1_do_locks_state);

        DBG_DEBUG("req=%p, state=%p, state->smbreq=%p\n",
                  req,
                  state,
                  state->smbreq);

        if (state->smbreq == NULL) {
                return false;
        }
        *psmbreq = talloc_move(mem_ctx, &state->smbreq);
        return true;
}

void smbd_smb1_brl_finish_by_req(struct tevent_req *req, NTSTATUS status)
{
        DBG_DEBUG("req=%p, status=%s\n", req, nt_errstr(status));

        if (NT_STATUS_IS_OK(status)) {
                tevent_req_done(req);
        } else {
                tevent_req_nterror(req, status);
        }
}

bool smbd_smb1_brl_finish_by_lock(
        struct files_struct *fsp,
        bool large_offset,
        struct smbd_lock_element lock,
        NTSTATUS finish_status)
{
        struct tevent_req **blocked = fsp->blocked_smb1_lock_reqs;
        size_t num_blocked = talloc_array_length(blocked);
        size_t i;

        DBG_DEBUG("num_blocked=%zu\n", num_blocked);

        for (i=0; i<num_blocked; i++) {
                struct tevent_req *req = blocked[i];
                struct smbd_smb1_do_locks_state *state = tevent_req_data(
                        req, struct smbd_smb1_do_locks_state);
                uint16_t j;

                DBG_DEBUG("i=%zu, req=%p\n", i, req);

                if (state->large_offset != large_offset) {
                        continue;
                }

                for (j=0; j<state->num_locks; j++) {
                        struct smbd_lock_element *l = &state->locks[j];

                        if ((lock.smblctx == l->smblctx) &&
                            (lock.offset == l->offset) &&
                            (lock.count == l->count)) {
                                smbd_smb1_brl_finish_by_req(
                                        req, finish_status);
                                return true;
                        }
                }
        }
        return false;
}

static struct files_struct *smbd_smb1_brl_finish_by_mid_fn(
        struct files_struct *fsp, void *private_data)
{
        struct tevent_req **blocked = fsp->blocked_smb1_lock_reqs;
        size_t num_blocked = talloc_array_length(blocked);
        uint64_t mid = *((uint64_t *)private_data);
        size_t i;

        DBG_DEBUG("fsp=%p, num_blocked=%zu\n", fsp, num_blocked);

        for (i=0; i<num_blocked; i++) {
                struct tevent_req *req = blocked[i];
                struct smbd_smb1_do_locks_state *state = tevent_req_data(
                        req, struct smbd_smb1_do_locks_state);
                struct smb_request *smbreq = state->smbreq;

                if (smbreq->mid == mid) {
                        tevent_req_nterror(req, NT_STATUS_FILE_LOCK_CONFLICT);
                        return fsp;
                }
        }

        return NULL;
}

/*
 * This walks the list of fsps, we store the blocked reqs attached to
 * them. It can be expensive, but this is legacy SMB1 and trying to
 * remember looking at traces I don't really see many of those calls.
 */

bool smbd_smb1_brl_finish_by_mid(
        struct smbd_server_connection *sconn, uint64_t mid)
{
        struct files_struct *found = files_forall(
                sconn, smbd_smb1_brl_finish_by_mid_fn, &mid);
        return (found != NULL);
}