/* * 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" 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: 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 *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; *devname = cifs_build_devname(ref->node_name, prepath); if (IS_ERR(*devname)) { rc = PTR_ERR(*devname); *devname = NULL; goto compose_mount_options_err; } rc = dns_resolve_server_name_to_ip(*devname, &srvIP); if (rc < 0) { cifs_dbg(FYI, "%s: Failed to resolve server part of %s to IP: %d\n", __func__, *devname, 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); /*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(*devname); *devname = NULL; 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 cifs_sb_info *cifs_sb, const char *fullpath, const struct dfs_info3_param *ref) { struct vfsmount *mnt; char *mountdata; char *devname = NULL; /* strip first '\' from fullpath */ mountdata = cifs_compose_mount_options(cifs_sb->mountdata, fullpath + 1, ref, &devname); if (IS_ERR(mountdata)) return (struct vfsmount *)mountdata; mnt = vfs_kern_mount(&cifs_fs_type, 0, 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: %hd, srv_type: %hd\n", ref->flags, ref->server_type); cifs_dbg(FYI, "DFS: ref_flags: %hd, path_consumed: %hd\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 *referrals = NULL; unsigned int num_referrals = 0; struct cifs_sb_info *cifs_sb; struct cifs_ses *ses; char *full_path; unsigned int xid; int i; int rc; struct vfsmount *mnt; struct tcon_link *tlink; 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); full_path = build_path_from_dentry(mntpt); if (full_path == NULL) goto cdda_exit; cifs_sb = CIFS_SB(d_inode(mntpt)->i_sb); tlink = cifs_sb_tlink(cifs_sb); if (IS_ERR(tlink)) { mnt = ERR_CAST(tlink); goto free_full_path; } ses = tlink_tcon(tlink)->ses; xid = get_xid(); rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls, &num_referrals, &referrals, cifs_remap(cifs_sb)); free_xid(xid); cifs_put_tlink(tlink); mnt = ERR_PTR(-ENOENT); for (i = 0; i < num_referrals; i++) { int len; dump_referral(referrals + i); /* connect to a node */ len = strlen(referrals[i].node_name); if (len < 2) { cifs_dbg(VFS, "%s: Net Address path too short: %s\n", __func__, referrals[i].node_name); mnt = ERR_PTR(-EINVAL); break; } mnt = cifs_dfs_do_refmount(cifs_sb, full_path, referrals + i); cifs_dbg(FYI, "%s: cifs_dfs_do_refmount:%s , mnt:%p\n", __func__, referrals[i].node_name, mnt); if (!IS_ERR(mnt)) goto success; } /* no valid submounts were found; return error from get_dfs_path() by * preference */ if (rc != 0) mnt = ERR_PTR(rc); success: free_dfs_info_array(referrals, num_referrals); 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 = { };