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![Jeff Layton](/assets/img/avatar_default.png)
With the change to ignore the unc= and prefixpath= mount options, there is no longer any need to add them to the options string when mounting. By the same token, we now need to build a device name that includes the prefixpath when mounting. To make things neater, the delimiters on the devicename are changed to '/' since that's preferred when mounting anyway. v2: fix some comments and don't bother looking at whether there is a prepath in the ref->node_name when deciding whether to pass a prepath to cifs_build_devname. v3: rebase on top of potential buffer overrun fix for stable Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
378 lines
9.8 KiB
C
378 lines
9.8 KiB
C
/*
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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/slab.h>
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#include <linux/vfs.h>
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#include <linux/fs.h>
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#include <linux/inet.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_sync(&cifs_dfs_automount_task);
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}
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/**
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* cifs_build_devname - build a devicename from a UNC and optional prepath
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* @nodename: pointer to UNC string
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* @prepath: pointer to prefixpath (or NULL if there isn't one)
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*
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* Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
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* big enough to hold the final thing. Copy the UNC from the nodename, and
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* concatenate the prepath onto the end of it if there is one.
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*
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* Returns pointer to the built string, or a ERR_PTR. Caller is responsible
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* for freeing the returned string.
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*/
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static char *
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cifs_build_devname(char *nodename, const char *prepath)
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{
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size_t pplen;
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size_t unclen;
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char *dev;
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char *pos;
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/* skip over any preceding delimiters */
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nodename += strspn(nodename, "\\");
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if (!*nodename)
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return ERR_PTR(-EINVAL);
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/* get length of UNC and set pos to last char */
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unclen = strlen(nodename);
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pos = nodename + unclen - 1;
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/* trim off any trailing delimiters */
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while (*pos == '\\') {
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--pos;
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--unclen;
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}
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/* allocate a buffer:
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* +2 for preceding "//"
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* +1 for delimiter between UNC and prepath
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* +1 for trailing NULL
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*/
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pplen = prepath ? strlen(prepath) : 0;
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dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
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if (!dev)
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return ERR_PTR(-ENOMEM);
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pos = dev;
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/* add the initial "//" */
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*pos = '/';
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++pos;
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*pos = '/';
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++pos;
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/* copy in the UNC portion from referral */
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memcpy(pos, nodename, unclen);
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pos += unclen;
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/* copy the prefixpath remainder (if there is one) */
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if (pplen) {
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*pos = '/';
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++pos;
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memcpy(pos, prepath, pplen);
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pos += pplen;
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}
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/* NULL terminator */
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*pos = '\0';
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convert_delimiter(dev, '/');
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return dev;
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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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const char *prepath = 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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if (strlen(fullpath) - ref->path_consumed)
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prepath = fullpath + ref->path_consumed;
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*devname = cifs_build_devname(ref->node_name, prepath);
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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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cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
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__func__, *devname, rc);
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goto compose_mount_options_err;
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}
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/*
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* In most cases, we'll be building a shorter string than the original,
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* but we do have to assume that the address in the ip= option may be
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* much longer than the original. Add the max length of an address
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* string to the length of the original string to allow for worst case.
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*/
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md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
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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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/*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
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/*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __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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kfree(*devname);
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*devname = NULL;
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goto compose_mount_options_out;
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}
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/**
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* cifs_dfs_do_refmount - mounts specified path using provided refferal
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* @cifs_sb: parent/root superblock
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* @fullpath: full path in UNC format
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* @ref: server's referral
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*/
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static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
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const char *fullpath, const struct dfs_info3_param *ref)
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{
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struct vfsmount *mnt;
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char *mountdata;
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char *devname = NULL;
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/* strip first '\' from fullpath */
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mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
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fullpath + 1, ref, &devname);
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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 void dump_referral(const struct dfs_info3_param *ref)
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{
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cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
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cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
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cifs_dbg(FYI, "DFS: fl: %hd, srv_type: %hd\n",
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ref->flags, ref->server_type);
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cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\n",
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ref->ref_flag, ref->path_consumed);
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}
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/*
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* Create a vfsmount that we can automount
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*/
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static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
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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 cifs_ses *ses;
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char *full_path;
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unsigned int xid;
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int i;
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int rc;
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struct vfsmount *mnt;
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struct tcon_link *tlink;
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cifs_dbg(FYI, "in %s\n", __func__);
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BUG_ON(IS_ROOT(mntpt));
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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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mnt = ERR_PTR(-ENOMEM);
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full_path = build_path_from_dentry(mntpt);
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if (full_path == NULL)
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goto cdda_exit;
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cifs_sb = CIFS_SB(mntpt->d_inode->i_sb);
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tlink = cifs_sb_tlink(cifs_sb);
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if (IS_ERR(tlink)) {
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mnt = ERR_CAST(tlink);
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goto free_full_path;
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}
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ses = tlink_tcon(tlink)->ses;
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xid = get_xid();
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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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free_xid(xid);
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cifs_put_tlink(tlink);
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mnt = ERR_PTR(-ENOENT);
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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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cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
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__func__, referrals[i].node_name);
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mnt = ERR_PTR(-EINVAL);
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break;
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}
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mnt = cifs_dfs_do_refmount(cifs_sb,
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full_path, referrals + i);
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cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n",
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__func__, referrals[i].node_name, mnt);
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if (!IS_ERR(mnt))
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goto success;
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}
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/* no valid submounts were found; return error from get_dfs_path() by
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* preference */
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if (rc != 0)
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mnt = ERR_PTR(rc);
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success:
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free_dfs_info_array(referrals, num_referrals);
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free_full_path:
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kfree(full_path);
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cdda_exit:
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cifs_dbg(FYI, "leaving %s\n" , __func__);
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return mnt;
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}
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/*
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* Attempt to automount the referral
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*/
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struct vfsmount *cifs_dfs_d_automount(struct path *path)
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{
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struct vfsmount *newmnt;
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cifs_dbg(FYI, "in %s\n", __func__);
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newmnt = cifs_dfs_do_automount(path->dentry);
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if (IS_ERR(newmnt)) {
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cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
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return newmnt;
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}
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mntget(newmnt); /* prevent immediate expiration */
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mnt_set_expiry(newmnt, &cifs_dfs_automount_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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cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
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return newmnt;
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}
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const struct inode_operations cifs_dfs_referral_inode_operations = {
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};
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