source: vendor/3.6.23/source3/smbd/files.c

/* 
   Unix SMB/CIFS implementation.
   Files[] structure handling
   Copyright (C) Andrew Tridgell 1998

   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 "smbd/smbd.h"
#include "smbd/globals.h"
#include "libcli/security/security.h"
#include "util_tdb.h"

#define VALID_FNUM(fnum)   (((fnum) >= 0) && ((fnum) < real_max_open_files))

#define FILE_HANDLE_OFFSET 0x1000

/****************************************************************************
 Return a unique number identifying this fsp over the life of this pid,
 and try to make it as globally unique as possible.
 See bug #8995 for the details.
****************************************************************************/

static unsigned long get_gen_count(struct smbd_server_connection *sconn)
{
        /*
         * While fsp->fh->gen_id is 'unsigned long' currently
         * (which might by 8 bytes),
         * there's some oplock code which truncates it to
         * uint32_t(using IVAL()).
         */
        if (sconn->file_gen_counter == 0) {
                sconn->file_gen_counter = generate_random();
        }
        sconn->file_gen_counter += 1;
        if (sconn->file_gen_counter >= UINT32_MAX) {
                sconn->file_gen_counter = 0;
        }
        if (sconn->file_gen_counter == 0) {
                sconn->file_gen_counter += 1;
        }
        return sconn->file_gen_counter;
}

/****************************************************************************
 Find first available file slot.
****************************************************************************/

NTSTATUS file_new(struct smb_request *req, connection_struct *conn,
                  files_struct **result)
{
        struct smbd_server_connection *sconn = conn->sconn;
        int i;
        files_struct *fsp;
        NTSTATUS status;

        /* we want to give out file handles differently on each new
           connection because of a common bug in MS clients where they try to
           reuse a file descriptor from an earlier smb connection. This code
           increases the chance that the errant client will get an error rather
           than causing corruption */
        if (sconn->first_file == 0) {
                sconn->first_file = (sys_getpid() ^ (int)time(NULL));
                sconn->first_file %= sconn->real_max_open_files;
        }

        /* TODO: Port the id-tree implementation from Samba4 */

        i = bitmap_find(sconn->file_bmap, sconn->first_file);
        if (i == -1) {
                DEBUG(0,("ERROR! Out of file structures\n"));
                /* TODO: We have to unconditionally return a DOS error here,
                 * W2k3 even returns ERRDOS/ERRnofids for ntcreate&x with
                 * NTSTATUS negotiated */
                return NT_STATUS_TOO_MANY_OPENED_FILES;
        }

        /*
         * Make a child of the connection_struct as an fsp can't exist
         * independent of a connection.
         */
        fsp = talloc_zero(conn, struct files_struct);
        if (!fsp) {
                return NT_STATUS_NO_MEMORY;
        }

        /*
         * This can't be a child of fsp because the file_handle can be ref'd
         * when doing a dos/fcb open, which will then share the file_handle
         * across multiple fsps.
         */
        fsp->fh = talloc_zero(conn, struct fd_handle);
        if (!fsp->fh) {
                TALLOC_FREE(fsp);
                return NT_STATUS_NO_MEMORY;
        }

        fsp->fh->ref_count = 1;
        fsp->fh->fd = -1;

        fsp->conn = conn;
        fsp->fh->gen_id = get_gen_count(sconn);
        GetTimeOfDay(&fsp->open_time);

        sconn->first_file = (i+1) % (sconn->real_max_open_files);

        bitmap_set(sconn->file_bmap, i);
        sconn->files_used += 1;

        fsp->fnum = i + FILE_HANDLE_OFFSET;
        SMB_ASSERT(fsp->fnum < 65536);

        /*
         * Create an smb_filename with "" for the base_name.  There are very
         * few NULL checks, so make sure it's initialized with something. to
         * be safe until an audit can be done.
         */
        status = create_synthetic_smb_fname(fsp, "", NULL, NULL,
                                            &fsp->fsp_name);
        if (!NT_STATUS_IS_OK(status)) {
                TALLOC_FREE(fsp);
                TALLOC_FREE(fsp->fh);
        }

        DLIST_ADD(sconn->files, fsp);

        DEBUG(5,("allocated file structure %d, fnum = %d (%d used)\n",
                 i, fsp->fnum, sconn->files_used));

        if (req != NULL) {
                req->chain_fsp = fsp;
        }

        /* A new fsp invalidates the positive and
          negative fsp_fi_cache as the new fsp is pushed
          at the start of the list and we search from
          a cache hit to the *end* of the list. */

        ZERO_STRUCT(sconn->fsp_fi_cache);

        conn->num_files_open++;

        *result = fsp;
        return NT_STATUS_OK;
}

/****************************************************************************
 Close all open files for a connection.
****************************************************************************/

void file_close_conn(connection_struct *conn)
{
        files_struct *fsp, *next;

        for (fsp=conn->sconn->files; fsp; fsp=next) {
                next = fsp->next;
                if (fsp->conn == conn) {
                        close_file(NULL, fsp, SHUTDOWN_CLOSE);
                }
        }
}

/****************************************************************************
 Close all open files for a pid and a vuid.
****************************************************************************/

void file_close_pid(struct smbd_server_connection *sconn, uint16 smbpid,
                    int vuid)
{
        files_struct *fsp, *next;

        for (fsp=sconn->files;fsp;fsp=next) {
                next = fsp->next;
                if ((fsp->file_pid == smbpid) && (fsp->vuid == vuid)) {
                        close_file(NULL, fsp, SHUTDOWN_CLOSE);
                }
        }
}

/****************************************************************************
 Initialise file structures.
****************************************************************************/

bool file_init(struct smbd_server_connection *sconn)
{
        int request_max_open_files = lp_max_open_files();
        int real_lim;

        /*
         * Set the max_open files to be the requested
         * max plus a fudgefactor to allow for the extra
         * fd's we need such as log files etc...
         */
        real_lim = set_maxfiles(request_max_open_files + MAX_OPEN_FUDGEFACTOR);

        sconn->real_max_open_files = real_lim - MAX_OPEN_FUDGEFACTOR;

        if (sconn->real_max_open_files + FILE_HANDLE_OFFSET + MAX_OPEN_PIPES
            > 65536)
                sconn->real_max_open_files =
                        65536 - FILE_HANDLE_OFFSET - MAX_OPEN_PIPES;

        if(sconn->real_max_open_files != request_max_open_files) {
                DEBUG(1, ("file_init: Information only: requested %d "
                          "open files, %d are available.\n",
                          request_max_open_files, sconn->real_max_open_files));
        }

        SMB_ASSERT(sconn->real_max_open_files > 100);

        sconn->file_bmap = bitmap_talloc(sconn, sconn->real_max_open_files);

        if (!sconn->file_bmap) {
                return false;
        }
        return true;
}

/****************************************************************************
 Close files open by a specified vuid.
****************************************************************************/

void file_close_user(struct smbd_server_connection *sconn, int vuid)
{
        files_struct *fsp, *next;

        for (fsp=sconn->files; fsp; fsp=next) {
                next=fsp->next;
                if (fsp->vuid == vuid) {
                        close_file(NULL, fsp, SHUTDOWN_CLOSE);
                }
        }
}

/*
 * Walk the files table until "fn" returns non-NULL
 */

struct files_struct *files_forall(
        struct smbd_server_connection *sconn,
        struct files_struct *(*fn)(struct files_struct *fsp,
                                   void *private_data),
        void *private_data)
{
        struct files_struct *fsp, *next;

        for (fsp = sconn->files; fsp; fsp = next) {
                struct files_struct *ret;
                next = fsp->next;
                ret = fn(fsp, private_data);
                if (ret != NULL) {
                        return ret;
                }
        }
        return NULL;
}

/****************************************************************************
 Find a fsp given a file descriptor.
****************************************************************************/

files_struct *file_find_fd(struct smbd_server_connection *sconn, int fd)
{
        int count=0;
        files_struct *fsp;

        for (fsp=sconn->files; fsp; fsp=fsp->next,count++) {
                if (fsp->fh->fd == fd) {
                        if (count > 10) {
                                DLIST_PROMOTE(sconn->files, fsp);
                        }
                        return fsp;
                }
        }

        return NULL;
}

/****************************************************************************
 Find a fsp given a device, inode and file_id.
****************************************************************************/

files_struct *file_find_dif(struct smbd_server_connection *sconn,
                            struct file_id id, unsigned long gen_id)
{
        int count=0;
        files_struct *fsp;

        if (gen_id == 0) {
                return NULL;
        }

        for (fsp=sconn->files; fsp; fsp=fsp->next,count++) {
                /* We can have a fsp->fh->fd == -1 here as it could be a stat open. */
                if (file_id_equal(&fsp->file_id, &id) &&
                    fsp->fh->gen_id == gen_id ) {
                        if (count > 10) {
                                DLIST_PROMOTE(sconn->files, fsp);
                        }
                        /* Paranoia check. */
                        if ((fsp->fh->fd == -1) &&
                            (fsp->oplock_type != NO_OPLOCK) &&
                            (fsp->oplock_type != FAKE_LEVEL_II_OPLOCK)) {
                                DEBUG(0,("file_find_dif: file %s file_id = "
                                         "%s, gen = %u oplock_type = %u is a "
                                         "stat open with oplock type !\n",
                                         fsp_str_dbg(fsp),
                                         file_id_string_tos(&fsp->file_id),
                                         (unsigned int)fsp->fh->gen_id,
                                         (unsigned int)fsp->oplock_type ));
                                smb_panic("file_find_dif");
                        }
                        return fsp;
                }
        }

        return NULL;
}

/****************************************************************************
 Find the first fsp given a device and inode.
 We use a singleton cache here to speed up searching from getfilepathinfo
 calls.
****************************************************************************/

files_struct *file_find_di_first(struct smbd_server_connection *sconn,
                                 struct file_id id)
{
        files_struct *fsp;

        if (file_id_equal(&sconn->fsp_fi_cache.id, &id)) {
                /* Positive or negative cache hit. */
                return sconn->fsp_fi_cache.fsp;
        }

        sconn->fsp_fi_cache.id = id;

        for (fsp=sconn->files;fsp;fsp=fsp->next) {
                if (file_id_equal(&fsp->file_id, &id)) {
                        /* Setup positive cache. */
                        sconn->fsp_fi_cache.fsp = fsp;
                        return fsp;
                }
        }

        /* Setup negative cache. */
        sconn->fsp_fi_cache.fsp = NULL;
        return NULL;
}

/****************************************************************************
 Find the next fsp having the same device and inode.
****************************************************************************/

files_struct *file_find_di_next(files_struct *start_fsp)
{
        files_struct *fsp;

        for (fsp = start_fsp->next;fsp;fsp=fsp->next) {
                if (file_id_equal(&fsp->file_id, &start_fsp->file_id)) {
                        return fsp;
                }
        }

        return NULL;
}

/****************************************************************************
 Find any fsp open with a pathname below that of an already open path.
****************************************************************************/

bool file_find_subpath(files_struct *dir_fsp)
{
        files_struct *fsp;
        size_t dlen;
        char *d_fullname = NULL;

        d_fullname = talloc_asprintf(talloc_tos(), "%s/%s",
                                     dir_fsp->conn->connectpath,
                                     dir_fsp->fsp_name->base_name);

        if (!d_fullname) {
                return false;
        }

        dlen = strlen(d_fullname);

        for (fsp=dir_fsp->conn->sconn->files; fsp; fsp=fsp->next) {
                char *d1_fullname;

                if (fsp == dir_fsp) {
                        continue;
                }

                d1_fullname = talloc_asprintf(talloc_tos(),
                                        "%s/%s",
                                        fsp->conn->connectpath,
                                        fsp->fsp_name->base_name);

                /*
                 * If the open file has a path that is a longer
                 * component, then it's a subpath.
                 */
                if (strnequal(d_fullname, d1_fullname, dlen) &&
                                (d1_fullname[dlen] == '/')) {
                        TALLOC_FREE(d1_fullname);
                        TALLOC_FREE(d_fullname);
                        return true;
                }
                TALLOC_FREE(d1_fullname);
        }

        TALLOC_FREE(d_fullname);
        return false;
}

/****************************************************************************
 Sync open files on a connection.
****************************************************************************/

void file_sync_all(connection_struct *conn)
{
        files_struct *fsp, *next;

        for (fsp=conn->sconn->files; fsp; fsp=next) {
                next=fsp->next;
                if ((conn == fsp->conn) && (fsp->fh->fd != -1)) {
                        sync_file(conn, fsp, True /* write through */);
                }
        }
}

/****************************************************************************
 Free up a fsp.
****************************************************************************/

void file_free(struct smb_request *req, files_struct *fsp)
{
        struct smbd_server_connection *sconn = fsp->conn->sconn;

        DLIST_REMOVE(sconn->files, fsp);

        TALLOC_FREE(fsp->fake_file_handle);

        if (fsp->fh->ref_count == 1) {
                TALLOC_FREE(fsp->fh);
        } else {
                fsp->fh->ref_count--;
        }

        if (fsp->notify) {
                if (fsp->is_directory) {
                        notify_remove_onelevel(fsp->conn->notify_ctx,
                                               &fsp->file_id, fsp);
                }
                notify_remove(fsp->conn->notify_ctx, fsp);
                TALLOC_FREE(fsp->notify);
        }

        /* Ensure this event will never fire. */
        TALLOC_FREE(fsp->oplock_timeout);

        /* Ensure this event will never fire. */
        TALLOC_FREE(fsp->update_write_time_event);

        bitmap_clear(sconn->file_bmap, fsp->fnum - FILE_HANDLE_OFFSET);
        sconn->files_used--;

        DEBUG(5,("freed files structure %d (%d used)\n",
                 fsp->fnum, sconn->files_used));

        fsp->conn->num_files_open--;

        if ((req != NULL) && (fsp == req->chain_fsp)) {
                req->chain_fsp = NULL;
        }

        /*
         * Clear all possible chained fsp
         * pointers in the SMB2 request queue.
         */
        if (req != NULL && req->smb2req) {
                remove_smb2_chained_fsp(fsp);
        }

        /* Closing a file can invalidate the positive cache. */
        if (fsp == sconn->fsp_fi_cache.fsp) {
                ZERO_STRUCT(sconn->fsp_fi_cache);
        }

        /* Drop all remaining extensions. */
        while (fsp->vfs_extension) {
                vfs_remove_fsp_extension(fsp->vfs_extension->owner, fsp);
        }

        /* this is paranoia, just in case someone tries to reuse the
           information */
        ZERO_STRUCTP(fsp);

        /* fsp->fsp_name is a talloc child and is free'd automatically. */
        TALLOC_FREE(fsp);
}

/****************************************************************************
 Get an fsp from a 16 bit fnum.
****************************************************************************/

static struct files_struct *file_fnum(struct smbd_server_connection *sconn,
                                      uint16 fnum)
{
        files_struct *fsp;
        int count=0;

        for (fsp=sconn->files; fsp; fsp=fsp->next, count++) {
                if (fsp->fnum == fnum) {
                        if (count > 10) {
                                DLIST_PROMOTE(sconn->files, fsp);
                        }
                        return fsp;
                }
        }
        return NULL;
}

/****************************************************************************
 Get an fsp from a packet given a 16 bit fnum.
****************************************************************************/

files_struct *file_fsp(struct smb_request *req, uint16 fid)
{
        files_struct *fsp;

        if (req == NULL) {
                /*
                 * We should never get here. req==NULL could in theory
                 * only happen from internal opens with a non-zero
                 * root_dir_fid. Internal opens just don't do that, at
                 * least they are not supposed to do so. And if they
                 * start to do so, they better fake up a smb_request
                 * from which we get the right smbd_server_conn. While
                 * this should never happen, let's return NULL here.
                 */
                return NULL;
        }

        if (req->chain_fsp != NULL) {
                return req->chain_fsp;
        }

        fsp = file_fnum(req->sconn, fid);
        if (fsp != NULL) {
                req->chain_fsp = fsp;
        }
        return fsp;
}

uint64_t fsp_persistent_id(const struct files_struct *fsp)
{
        uint64_t persistent_id;

        /*
         * This calculates a number that is most likely
         * globally unique. In future we will have a database
         * to make it completely unique.
         *
         * 32-bit random gen_id
         * 16-bit truncated open_time
         * 16-bit fnum (valatile_id)
         */
        persistent_id = fsp->fh->gen_id & UINT32_MAX;
        persistent_id <<= 16;
        persistent_id &= 0x0000FFFFFFFF0000LLU;
        persistent_id |= fsp->open_time.tv_usec & UINT16_MAX;
        persistent_id <<= 16;
        persistent_id &= 0xFFFFFFFFFFFF0000LLU;
        persistent_id |= fsp->fnum & UINT16_MAX;

        return persistent_id;
}

struct files_struct *file_fsp_smb2(struct smbd_smb2_request *smb2req,
                                   uint64_t persistent_id,
                                   uint64_t volatile_id)
{
        struct files_struct *fsp;
        uint64_t fsp_persistent;

        if (smb2req->compat_chain_fsp != NULL) {
                return smb2req->compat_chain_fsp;
        }

        if (volatile_id > UINT16_MAX) {
                return NULL;
        }

        fsp = file_fnum(smb2req->sconn, (uint16_t)volatile_id);
        if (fsp == NULL) {
                return NULL;
        }
        fsp_persistent = fsp_persistent_id(fsp);

        if (persistent_id != fsp_persistent) {
                return NULL;
        }

        if (smb2req->tcon == NULL) {
                return NULL;
        }

        if (smb2req->tcon->compat_conn != fsp->conn) {
                return NULL;
        }

        if (smb2req->session == NULL) {
                return NULL;
        }

        if (smb2req->session->vuid != fsp->vuid) {
                return NULL;
        }

        smb2req->compat_chain_fsp = fsp;
        return fsp;
}

/****************************************************************************
 Duplicate the file handle part for a DOS or FCB open.
****************************************************************************/

NTSTATUS dup_file_fsp(struct smb_request *req, files_struct *from,
                      uint32 access_mask, uint32 share_access,
                      uint32 create_options, files_struct *to)
{
        TALLOC_FREE(to->fh);

        to->fh = from->fh;
        to->fh->ref_count++;

        to->file_id = from->file_id;
        to->initial_allocation_size = from->initial_allocation_size;
        to->mode = from->mode;
        to->file_pid = from->file_pid;
        to->vuid = from->vuid;
        to->open_time = from->open_time;
        to->access_mask = access_mask;
        to->share_access = share_access;
        to->oplock_type = from->oplock_type;
        to->can_lock = from->can_lock;
        to->can_read = (access_mask & (FILE_READ_DATA)) ? True : False;
        if (!CAN_WRITE(from->conn)) {
                to->can_write = False;
        } else {
                to->can_write = (access_mask & (FILE_WRITE_DATA | FILE_APPEND_DATA)) ? True : False;
        }
        to->modified = from->modified;
        to->is_directory = from->is_directory;
        to->aio_write_behind = from->aio_write_behind;

        if (from->print_file) {
                to->print_file = talloc(to, struct print_file_data);
                if (!to->print_file) return NT_STATUS_NO_MEMORY;
                to->print_file->rap_jobid = from->print_file->rap_jobid;
        } else {
                to->print_file = NULL;
        }

        return fsp_set_smb_fname(to, from->fsp_name);
}

/**
 * Return a jenkins hash of a pathname on a connection.
 */

NTSTATUS file_name_hash(connection_struct *conn,
                        const char *name, uint32_t *p_name_hash)
{
        TDB_DATA key;
        char *fullpath = NULL;

        /* Set the hash of the full pathname. */
        fullpath = talloc_asprintf(talloc_tos(),
                        "%s/%s",
                        conn->connectpath,
                        name);
        if (!fullpath) {
                return NT_STATUS_NO_MEMORY;
        }
        key = string_term_tdb_data(fullpath);
        *p_name_hash = tdb_jenkins_hash(&key);

        DEBUG(10,("file_name_hash: %s hash 0x%x\n",
                fullpath,
                (unsigned int)*p_name_hash ));

        TALLOC_FREE(fullpath);
        return NT_STATUS_OK;
}

/**
 * The only way that the fsp->fsp_name field should ever be set.
 */
NTSTATUS fsp_set_smb_fname(struct files_struct *fsp,
                           const struct smb_filename *smb_fname_in)
{
        NTSTATUS status;
        struct smb_filename *smb_fname_new;

        status = copy_smb_filename(fsp, smb_fname_in, &smb_fname_new);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        TALLOC_FREE(fsp->fsp_name);
        fsp->fsp_name = smb_fname_new;

        return file_name_hash(fsp->conn,
                        smb_fname_str_dbg(fsp->fsp_name),
                        &fsp->name_hash);
}