/fs/cifs/cifs_dfs_ref.c
C | 425 lines | 284 code | 55 blank | 86 comment | 42 complexity | 07808a4912075d6792e0b78c27f654fa MD5 | raw file
- /*
- * Contains the CIFS DFS referral mounting routines used for handling
- * traversal via DFS junction point
- *
- * Copyright (c) 2007 Igor Mammedov
- * Copyright (C) International Business Machines Corp., 2008
- * Author(s): Igor Mammedov (niallain@gmail.com)
- * Steve French (sfrench@us.ibm.com)
- * 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
- * 2 of the License, or (at your option) any later version.
- */
- #include <linux/dcache.h>
- #include <linux/mount.h>
- #include <linux/namei.h>
- #include <linux/slab.h>
- #include <linux/vfs.h>
- #include <linux/fs.h>
- #include <linux/inet.h>
- #include "cifsglob.h"
- #include "cifsproto.h"
- #include "cifsfs.h"
- #include "dns_resolve.h"
- #include "cifs_debug.h"
- #include "cifs_unicode.h"
- #include "dfs_cache.h"
- static LIST_HEAD(cifs_dfs_automount_list);
- static void cifs_dfs_expire_automounts(struct work_struct *work);
- static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
- cifs_dfs_expire_automounts);
- static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
- static void cifs_dfs_expire_automounts(struct work_struct *work)
- {
- struct list_head *list = &cifs_dfs_automount_list;
- mark_mounts_for_expiry(list);
- if (!list_empty(list))
- schedule_delayed_work(&cifs_dfs_automount_task,
- cifs_dfs_mountpoint_expiry_timeout);
- }
- void cifs_dfs_release_automount_timer(void)
- {
- BUG_ON(!list_empty(&cifs_dfs_automount_list));
- cancel_delayed_work_sync(&cifs_dfs_automount_task);
- }
- /**
- * cifs_build_devname - build a devicename from a UNC and optional prepath
- * @nodename: pointer to UNC string
- * @prepath: pointer to prefixpath (or NULL if there isn't one)
- *
- * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
- * big enough to hold the final thing. Copy the UNC from the nodename, and
- * concatenate the prepath onto the end of it if there is one.
- *
- * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
- * for freeing the returned string.
- */
- static char *
- cifs_build_devname(char *nodename, const char *prepath)
- {
- size_t pplen;
- size_t unclen;
- char *dev;
- char *pos;
- /* skip over any preceding delimiters */
- nodename += strspn(nodename, "\\");
- if (!*nodename)
- return ERR_PTR(-EINVAL);
- /* get length of UNC and set pos to last char */
- unclen = strlen(nodename);
- pos = nodename + unclen - 1;
- /* trim off any trailing delimiters */
- while (*pos == '\\') {
- --pos;
- --unclen;
- }
- /* allocate a buffer:
- * +2 for preceding "//"
- * +1 for delimiter between UNC and prepath
- * +1 for trailing NULL
- */
- pplen = prepath ? strlen(prepath) : 0;
- dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
- if (!dev)
- return ERR_PTR(-ENOMEM);
- pos = dev;
- /* add the initial "//" */
- *pos = '/';
- ++pos;
- *pos = '/';
- ++pos;
- /* copy in the UNC portion from referral */
- memcpy(pos, nodename, unclen);
- pos += unclen;
- /* copy the prefixpath remainder (if there is one) */
- if (pplen) {
- *pos = '/';
- ++pos;
- memcpy(pos, prepath, pplen);
- pos += pplen;
- }
- /* NULL terminator */
- *pos = '\0';
- convert_delimiter(dev, '/');
- return dev;
- }
- /**
- * cifs_compose_mount_options - creates mount options for refferral
- * @sb_mountdata: parent/root DFS mount options (template)
- * @fullpath: full path in UNC format
- * @ref: server's referral
- * @devname: optional pointer for saving device name
- *
- * creates mount options for submount based on template options sb_mountdata
- * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
- *
- * Returns: pointer to new mount options or ERR_PTR.
- * Caller is responcible for freeing retunrned value if it is not error.
- */
- char *cifs_compose_mount_options(const char *sb_mountdata,
- const char *fullpath,
- const struct dfs_info3_param *ref,
- char **devname)
- {
- int rc;
- char *name;
- char *mountdata = NULL;
- const char *prepath = NULL;
- int md_len;
- char *tkn_e;
- char *srvIP = NULL;
- char sep = ',';
- int off, noff;
- if (sb_mountdata == NULL)
- return ERR_PTR(-EINVAL);
- if (strlen(fullpath) - ref->path_consumed) {
- prepath = fullpath + ref->path_consumed;
- /* skip initial delimiter */
- if (*prepath == '/' || *prepath == '\\')
- prepath++;
- }
- name = cifs_build_devname(ref->node_name, prepath);
- if (IS_ERR(name)) {
- rc = PTR_ERR(name);
- name = NULL;
- goto compose_mount_options_err;
- }
- rc = dns_resolve_server_name_to_ip(name, &srvIP);
- if (rc < 0) {
- cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n",
- __func__, name, rc);
- goto compose_mount_options_err;
- }
- /*
- * In most cases, we'll be building a shorter string than the original,
- * but we do have to assume that the address in the ip= option may be
- * much longer than the original. Add the max length of an address
- * string to the length of the original string to allow for worst case.
- */
- md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
- mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
- if (mountdata == NULL) {
- rc = -ENOMEM;
- goto compose_mount_options_err;
- }
- /* copy all options except of unc,ip,prefixpath */
- off = 0;
- if (strncmp(sb_mountdata, "sep=", 4) == 0) {
- sep = sb_mountdata[4];
- strncpy(mountdata, sb_mountdata, 5);
- off += 5;
- }
- do {
- tkn_e = strchr(sb_mountdata + off, sep);
- if (tkn_e == NULL)
- noff = strlen(sb_mountdata + off);
- else
- noff = tkn_e - (sb_mountdata + off) + 1;
- if (strncasecmp(sb_mountdata + off, "unc=", 4) == 0) {
- off += noff;
- continue;
- }
- if (strncasecmp(sb_mountdata + off, "ip=", 3) == 0) {
- off += noff;
- continue;
- }
- if (strncasecmp(sb_mountdata + off, "prefixpath=", 11) == 0) {
- off += noff;
- continue;
- }
- strncat(mountdata, sb_mountdata + off, noff);
- off += noff;
- } while (tkn_e);
- strcat(mountdata, sb_mountdata + off);
- mountdata[md_len] = '\0';
- /* copy new IP and ref share name */
- if (mountdata[strlen(mountdata) - 1] != sep)
- strncat(mountdata, &sep, 1);
- strcat(mountdata, "ip=");
- strcat(mountdata, srvIP);
- if (devname)
- *devname = name;
- /*cifs_dbg(FYI, "%s: parent mountdata: %s\n", __func__, sb_mountdata);*/
- /*cifs_dbg(FYI, "%s: submount mountdata: %s\n", __func__, mountdata );*/
- compose_mount_options_out:
- kfree(srvIP);
- return mountdata;
- compose_mount_options_err:
- kfree(mountdata);
- mountdata = ERR_PTR(rc);
- kfree(name);
- goto compose_mount_options_out;
- }
- /**
- * cifs_dfs_do_refmount - mounts specified path using provided refferal
- * @cifs_sb: parent/root superblock
- * @fullpath: full path in UNC format
- * @ref: server's referral
- */
- static struct vfsmount *cifs_dfs_do_refmount(struct dentry *mntpt,
- struct cifs_sb_info *cifs_sb,
- const char *fullpath, const struct dfs_info3_param *ref)
- {
- struct vfsmount *mnt;
- char *mountdata;
- char *devname;
- /*
- * Always pass down the DFS full path to smb3_do_mount() so we
- * can use it later for failover.
- */
- devname = kstrndup(fullpath, strlen(fullpath), GFP_KERNEL);
- if (!devname)
- return ERR_PTR(-ENOMEM);
- convert_delimiter(devname, '/');
- /* strip first '\' from fullpath */
- mountdata = cifs_compose_mount_options(cifs_sb->mountdata,
- fullpath + 1, ref, NULL);
- if (IS_ERR(mountdata)) {
- kfree(devname);
- return (struct vfsmount *)mountdata;
- }
- mnt = vfs_submount(mntpt, &cifs_fs_type, devname, mountdata);
- kfree(mountdata);
- kfree(devname);
- return mnt;
- }
- static void dump_referral(const struct dfs_info3_param *ref)
- {
- cifs_dbg(FYI, "DFS: ref path: %s\n", ref->path_name);
- cifs_dbg(FYI, "DFS: node path: %s\n", ref->node_name);
- cifs_dbg(FYI, "DFS: fl: %d, srv_type: %d\n",
- ref->flags, ref->server_type);
- cifs_dbg(FYI, "DFS: ref_flags: %d, path_consumed: %d\n",
- ref->ref_flag, ref->path_consumed);
- }
- /*
- * Create a vfsmount that we can automount
- */
- static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
- {
- struct dfs_info3_param referral = {0};
- struct cifs_sb_info *cifs_sb;
- struct cifs_ses *ses;
- struct cifs_tcon *tcon;
- char *full_path, *root_path;
- unsigned int xid;
- int len;
- int rc;
- struct vfsmount *mnt;
- cifs_dbg(FYI, "in %s\n", __func__);
- BUG_ON(IS_ROOT(mntpt));
- /*
- * The MSDFS spec states that paths in DFS referral requests and
- * responses must be prefixed by a single '\' character instead of
- * the double backslashes usually used in the UNC. This function
- * gives us the latter, so we must adjust the result.
- */
- mnt = ERR_PTR(-ENOMEM);
- cifs_sb = CIFS_SB(mntpt->d_sb);
- if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) {
- mnt = ERR_PTR(-EREMOTE);
- goto cdda_exit;
- }
- /* always use tree name prefix */
- full_path = build_path_from_dentry_optional_prefix(mntpt, true);
- if (full_path == NULL)
- goto cdda_exit;
- cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);
- if (!cifs_sb_master_tlink(cifs_sb)) {
- cifs_dbg(FYI, "%s: master tlink is NULL\n", __func__);
- goto free_full_path;
- }
- tcon = cifs_sb_master_tcon(cifs_sb);
- if (!tcon) {
- cifs_dbg(FYI, "%s: master tcon is NULL\n", __func__);
- goto free_full_path;
- }
- root_path = kstrdup(tcon->treeName, GFP_KERNEL);
- if (!root_path) {
- mnt = ERR_PTR(-ENOMEM);
- goto free_full_path;
- }
- cifs_dbg(FYI, "%s: root path: %s\n", __func__, root_path);
- ses = tcon->ses;
- xid = get_xid();
- /*
- * If DFS root has been expired, then unconditionally fetch it again to
- * refresh DFS referral cache.
- */
- rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
- root_path + 1, NULL, NULL);
- if (!rc) {
- rc = dfs_cache_find(xid, ses, cifs_sb->local_nls,
- cifs_remap(cifs_sb), full_path + 1,
- &referral, NULL);
- }
- free_xid(xid);
- if (rc) {
- mnt = ERR_PTR(rc);
- goto free_root_path;
- }
- dump_referral(&referral);
- len = strlen(referral.node_name);
- if (len < 2) {
- cifs_dbg(VFS, "%s: Net Address path too short: %s\n",
- __func__, referral.node_name);
- mnt = ERR_PTR(-EINVAL);
- goto free_dfs_ref;
- }
- /*
- * cifs_mount() will retry every available node server in case
- * of failures.
- */
- mnt = cifs_dfs_do_refmount(mntpt, cifs_sb, full_path, &referral);
- cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n", __func__,
- referral.node_name, mnt);
- free_dfs_ref:
- free_dfs_info_param(&referral);
- free_root_path:
- kfree(root_path);
- free_full_path:
- kfree(full_path);
- cdda_exit:
- cifs_dbg(FYI, "leaving %s\n" , __func__);
- return mnt;
- }
- /*
- * Attempt to automount the referral
- */
- struct vfsmount *cifs_dfs_d_automount(struct path *path)
- {
- struct vfsmount *newmnt;
- cifs_dbg(FYI, "in %s\n", __func__);
- newmnt = cifs_dfs_do_automount(path->dentry);
- if (IS_ERR(newmnt)) {
- cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
- return newmnt;
- }
- mntget(newmnt); /* prevent immediate expiration */
- mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
- schedule_delayed_work(&cifs_dfs_automount_task,
- cifs_dfs_mountpoint_expiry_timeout);
- cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
- return newmnt;
- }
- const struct inode_operations cifs_dfs_referral_inode_operations = {
- };