392 lines
9.9 KiB
C
392 lines
9.9 KiB
C
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/*
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* Contains the CIFS DFS referral mounting routines used for handling
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* traversal via DFS junction point
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*
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* Copyright (c) 2007 Igor Mammedov
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* Copyright (C) International Business Machines Corp., 2008
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* Author(s): Igor Mammedov (niallain@gmail.com)
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* Steve French (sfrench@us.ibm.com)
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/dcache.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include <linux/vfs.h>
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#include <linux/fs.h>
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifsfs.h"
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#include "dns_resolve.h"
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#include "cifs_debug.h"
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static LIST_HEAD(cifs_dfs_automount_list);
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static void cifs_dfs_expire_automounts(struct work_struct *work);
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static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
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cifs_dfs_expire_automounts);
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static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
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static void cifs_dfs_expire_automounts(struct work_struct *work)
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{
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struct list_head *list = &cifs_dfs_automount_list;
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mark_mounts_for_expiry(list);
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if (!list_empty(list))
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schedule_delayed_work(&cifs_dfs_automount_task,
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cifs_dfs_mountpoint_expiry_timeout);
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}
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void cifs_dfs_release_automount_timer(void)
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{
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BUG_ON(!list_empty(&cifs_dfs_automount_list));
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cancel_delayed_work(&cifs_dfs_automount_task);
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flush_scheduled_work();
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}
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/**
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* cifs_get_share_name - extracts share name from UNC
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* @node_name: pointer to UNC string
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*
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* Extracts sharename form full UNC.
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* i.e. strips from UNC trailing path that is not part of share
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* name and fixup missing '\' in the begining of DFS node refferal
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* if neccessary.
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* Returns pointer to share name on success or ERR_PTR on error.
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* Caller is responsible for freeing returned string.
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*/
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static char *cifs_get_share_name(const char *node_name)
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{
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int len;
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char *UNC;
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char *pSep;
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len = strlen(node_name);
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UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
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GFP_KERNEL);
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if (!UNC)
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return ERR_PTR(-ENOMEM);
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/* get share name and server name */
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if (node_name[1] != '\\') {
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UNC[0] = '\\';
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strncpy(UNC+1, node_name, len);
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len++;
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UNC[len] = 0;
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} else {
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strncpy(UNC, node_name, len);
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UNC[len] = 0;
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}
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/* find server name end */
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pSep = memchr(UNC+2, '\\', len-2);
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if (!pSep) {
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cERROR(1, ("%s: no server name end in node name: %s",
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__func__, node_name));
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kfree(UNC);
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return ERR_PTR(-EINVAL);
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}
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/* find sharename end */
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pSep++;
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pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
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if (pSep) {
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/* trim path up to sharename end
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* now we have share name in UNC */
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*pSep = 0;
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}
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return UNC;
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}
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/**
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* cifs_compose_mount_options - creates mount options for refferral
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* @sb_mountdata: parent/root DFS mount options (template)
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* @fullpath: full path in UNC format
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* @ref: server's referral
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* @devname: pointer for saving device name
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*
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* creates mount options for submount based on template options sb_mountdata
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* and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
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*
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* Returns: pointer to new mount options or ERR_PTR.
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* Caller is responcible for freeing retunrned value if it is not error.
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*/
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char *cifs_compose_mount_options(const char *sb_mountdata,
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const char *fullpath,
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const struct dfs_info3_param *ref,
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char **devname)
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{
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int rc;
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char *mountdata = NULL;
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int md_len;
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char *tkn_e;
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char *srvIP = NULL;
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char sep = ',';
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int off, noff;
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if (sb_mountdata == NULL)
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return ERR_PTR(-EINVAL);
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*devname = cifs_get_share_name(ref->node_name);
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if (IS_ERR(*devname)) {
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rc = PTR_ERR(*devname);
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*devname = NULL;
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goto compose_mount_options_err;
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}
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rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
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if (rc != 0) {
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cERROR(1, ("%s: Failed to resolve server part of %s to IP: %d",
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__func__, *devname, rc));
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goto compose_mount_options_err;
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}
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/* md_len = strlen(...) + 12 for 'sep+prefixpath='
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* assuming that we have 'unc=' and 'ip=' in
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* the original sb_mountdata
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*/
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md_len = strlen(sb_mountdata) + strlen(srvIP) +
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strlen(ref->node_name) + 12;
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mountdata = kzalloc(md_len+1, GFP_KERNEL);
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if (mountdata == NULL) {
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rc = -ENOMEM;
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goto compose_mount_options_err;
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}
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/* copy all options except of unc,ip,prefixpath */
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off = 0;
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if (strncmp(sb_mountdata, "sep=", 4) == 0) {
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sep = sb_mountdata[4];
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strncpy(mountdata, sb_mountdata, 5);
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off += 5;
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}
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do {
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tkn_e = strchr(sb_mountdata + off, sep);
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if (tkn_e == NULL)
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noff = strlen(sb_mountdata + off);
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else
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noff = tkn_e - (sb_mountdata + off) + 1;
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if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) {
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off += noff;
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continue;
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}
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if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) {
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off += noff;
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continue;
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}
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if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
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off += noff;
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continue;
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}
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strncat(mountdata, sb_mountdata + off, noff);
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off += noff;
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} while (tkn_e);
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strcat(mountdata, sb_mountdata + off);
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mountdata[md_len] = '\0';
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/* copy new IP and ref share name */
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if (mountdata[strlen(mountdata) - 1] != sep)
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strncat(mountdata, &sep, 1);
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strcat(mountdata, "ip=");
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strcat(mountdata, srvIP);
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strncat(mountdata, &sep, 1);
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strcat(mountdata, "unc=");
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strcat(mountdata, *devname);
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/* find & copy prefixpath */
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tkn_e = strchr(ref->node_name + 2, '\\');
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if (tkn_e == NULL) {
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/* invalid unc, missing share name*/
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rc = -EINVAL;
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goto compose_mount_options_err;
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}
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tkn_e = strchr(tkn_e + 1, '\\');
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if (tkn_e || (strlen(fullpath) - ref->path_consumed)) {
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strncat(mountdata, &sep, 1);
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strcat(mountdata, "prefixpath=");
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if (tkn_e)
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strcat(mountdata, tkn_e + 1);
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strcat(mountdata, fullpath + ref->path_consumed);
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}
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/*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/
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/*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/
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compose_mount_options_out:
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kfree(srvIP);
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return mountdata;
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compose_mount_options_err:
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kfree(mountdata);
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mountdata = ERR_PTR(rc);
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goto compose_mount_options_out;
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}
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static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
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struct dentry *dentry, const struct dfs_info3_param *ref)
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{
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struct cifs_sb_info *cifs_sb;
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struct vfsmount *mnt;
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char *mountdata;
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char *devname = NULL;
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char *fullpath;
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cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
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/*
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* this function gives us a path with a double backslash prefix. We
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* require a single backslash for DFS.
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*/
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fullpath = build_path_from_dentry(dentry);
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if (!fullpath)
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return ERR_PTR(-ENOMEM);
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mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
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fullpath + 1, ref, &devname);
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kfree(fullpath);
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if (IS_ERR(mountdata))
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return (struct vfsmount *)mountdata;
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mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
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kfree(mountdata);
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kfree(devname);
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return mnt;
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}
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static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
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struct list_head *mntlist)
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{
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/* stolen from afs code */
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int err;
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mntget(newmnt);
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err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags, mntlist);
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switch (err) {
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case 0:
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path_put(&nd->path);
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nd->path.mnt = newmnt;
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nd->path.dentry = dget(newmnt->mnt_root);
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schedule_delayed_work(&cifs_dfs_automount_task,
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cifs_dfs_mountpoint_expiry_timeout);
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break;
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case -EBUSY:
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/* someone else made a mount here whilst we were busy */
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while (d_mountpoint(nd->path.dentry) &&
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follow_down(&nd->path))
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;
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err = 0;
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default:
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mntput(newmnt);
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break;
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}
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return err;
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}
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static void dump_referral(const struct dfs_info3_param *ref)
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{
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cFYI(1, ("DFS: ref path: %s", ref->path_name));
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cFYI(1, ("DFS: node path: %s", ref->node_name));
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cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
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cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
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ref->path_consumed));
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}
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static void*
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cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
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{
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struct dfs_info3_param *referrals = NULL;
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unsigned int num_referrals = 0;
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struct cifs_sb_info *cifs_sb;
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struct cifsSesInfo *ses;
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char *full_path = NULL;
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int xid, i;
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int rc = 0;
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struct vfsmount *mnt = ERR_PTR(-ENOENT);
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cFYI(1, ("in %s", __func__));
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BUG_ON(IS_ROOT(dentry));
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xid = GetXid();
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dput(nd->path.dentry);
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nd->path.dentry = dget(dentry);
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cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
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ses = cifs_sb->tcon->ses;
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if (!ses) {
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rc = -EINVAL;
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goto out_err;
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}
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/*
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* The MSDFS spec states that paths in DFS referral requests and
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* responses must be prefixed by a single '\' character instead of
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* the double backslashes usually used in the UNC. This function
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* gives us the latter, so we must adjust the result.
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*/
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full_path = build_path_from_dentry(dentry);
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if (full_path == NULL) {
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rc = -ENOMEM;
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goto out_err;
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}
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rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls,
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&num_referrals, &referrals,
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cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
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for (i = 0; i < num_referrals; i++) {
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int len;
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dump_referral(referrals+i);
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/* connect to a node */
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len = strlen(referrals[i].node_name);
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if (len < 2) {
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cERROR(1, ("%s: Net Address path too short: %s",
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__func__, referrals[i].node_name));
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rc = -EINVAL;
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goto out_err;
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}
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mnt = cifs_dfs_do_refmount(nd->path.mnt,
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nd->path.dentry, referrals + i);
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cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
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referrals[i].node_name, mnt));
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|
|
/* complete mount procedure if we accured submount */
|
||
|
|
if (!IS_ERR(mnt))
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* we need it cause for() above could exit without valid submount */
|
||
|
|
rc = PTR_ERR(mnt);
|
||
|
|
if (IS_ERR(mnt))
|
||
|
|
goto out_err;
|
||
|
|
|
||
|
|
nd->path.mnt->mnt_flags |= MNT_SHRINKABLE;
|
||
|
|
rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
|
||
|
|
|
||
|
|
out:
|
||
|
|
FreeXid(xid);
|
||
|
|
free_dfs_info_array(referrals, num_referrals);
|
||
|
|
kfree(full_path);
|
||
|
|
cFYI(1, ("leaving %s" , __func__));
|
||
|
|
return ERR_PTR(rc);
|
||
|
|
out_err:
|
||
|
|
path_put(&nd->path);
|
||
|
|
goto out;
|
||
|
|
}
|
||
|
|
|
||
|
|
const struct inode_operations cifs_dfs_referral_inode_operations = {
|
||
|
|
.follow_link = cifs_dfs_follow_mountpoint,
|
||
|
|
};
|
||
|
|
|