1/* 2 * Contains the CIFS DFS referral mounting routines used for handling 3 * traversal via DFS junction point 4 * 5 * Copyright (c) 2007 Igor Mammedov 6 * Copyright (C) International Business Machines Corp., 2008 7 * Author(s): Igor Mammedov (niallain@gmail.com) 8 * Steve French (sfrench@us.ibm.com) 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 */ 14 15#include <linux/dcache.h> 16#include <linux/mount.h> 17#include <linux/namei.h> 18#include <linux/slab.h> 19#include <linux/vfs.h> 20#include <linux/fs.h> 21#include "cifsglob.h" 22#include "cifsproto.h" 23#include "cifsfs.h" 24#include "dns_resolve.h" 25#include "cifs_debug.h" 26 27static LIST_HEAD(cifs_dfs_automount_list); 28 29static void cifs_dfs_expire_automounts(struct work_struct *work); 30static DECLARE_DELAYED_WORK(cifs_dfs_automount_task, 31 cifs_dfs_expire_automounts); 32static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ; 33 34static void cifs_dfs_expire_automounts(struct work_struct *work) 35{ 36 struct list_head *list = &cifs_dfs_automount_list; 37 38 mark_mounts_for_expiry(list); 39 if (!list_empty(list)) 40 schedule_delayed_work(&cifs_dfs_automount_task, 41 cifs_dfs_mountpoint_expiry_timeout); 42} 43 44void cifs_dfs_release_automount_timer(void) 45{ 46 BUG_ON(!list_empty(&cifs_dfs_automount_list)); 47 cancel_delayed_work(&cifs_dfs_automount_task); 48 flush_scheduled_work(); 49} 50 51/** 52 * cifs_get_share_name - extracts share name from UNC 53 * @node_name: pointer to UNC string 54 * 55 * Extracts sharename form full UNC. 56 * i.e. strips from UNC trailing path that is not part of share 57 * name and fixup missing '\' in the begining of DFS node refferal 58 * if necessary. 59 * Returns pointer to share name on success or ERR_PTR on error. 60 * Caller is responsible for freeing returned string. 61 */ 62static char *cifs_get_share_name(const char *node_name) 63{ 64 int len; 65 char *UNC; 66 char *pSep; 67 68 len = strlen(node_name); 69 UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */, 70 GFP_KERNEL); 71 if (!UNC) 72 return ERR_PTR(-ENOMEM); 73 74 /* get share name and server name */ 75 if (node_name[1] != '\\') { 76 UNC[0] = '\\'; 77 strncpy(UNC+1, node_name, len); 78 len++; 79 UNC[len] = 0; 80 } else { 81 strncpy(UNC, node_name, len); 82 UNC[len] = 0; 83 } 84 85 /* find server name end */ 86 pSep = memchr(UNC+2, '\\', len-2); 87 if (!pSep) { 88 cERROR(1, "%s: no server name end in node name: %s", 89 __func__, node_name); 90 kfree(UNC); 91 return ERR_PTR(-EINVAL); 92 } 93 94 /* find sharename end */ 95 pSep++; 96 pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC)); 97 if (pSep) { 98 /* trim path up to sharename end 99 * now we have share name in UNC */ 100 *pSep = 0; 101 } 102 103 return UNC; 104} 105 106 107/** 108 * cifs_compose_mount_options - creates mount options for refferral 109 * @sb_mountdata: parent/root DFS mount options (template) 110 * @fullpath: full path in UNC format 111 * @ref: server's referral 112 * @devname: pointer for saving device name 113 * 114 * creates mount options for submount based on template options sb_mountdata 115 * and replacing unc,ip,prefixpath options with ones we've got form ref_unc. 116 * 117 * Returns: pointer to new mount options or ERR_PTR. 118 * Caller is responcible for freeing retunrned value if it is not error. 119 */ 120char *cifs_compose_mount_options(const char *sb_mountdata, 121 const char *fullpath, 122 const struct dfs_info3_param *ref, 123 char **devname) 124{ 125 int rc; 126 char *mountdata = NULL; 127 int md_len; 128 char *tkn_e; 129 char *srvIP = NULL; 130 char sep = ','; 131 int off, noff; 132 133 if (sb_mountdata == NULL) 134 return ERR_PTR(-EINVAL); 135 136 *devname = cifs_get_share_name(ref->node_name); 137 if (IS_ERR(*devname)) { 138 rc = PTR_ERR(*devname); 139 *devname = NULL; 140 goto compose_mount_options_err; 141 } 142 143 rc = dns_resolve_server_name_to_ip(*devname, &srvIP); 144 if (rc < 0) { 145 cERROR(1, "%s: Failed to resolve server part of %s to IP: %d", 146 __func__, *devname, rc); 147 goto compose_mount_options_err; 148 } 149 /* md_len = strlen(...) + 12 for 'sep+prefixpath=' 150 * assuming that we have 'unc=' and 'ip=' in 151 * the original sb_mountdata 152 */ 153 md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12; 154 mountdata = kzalloc(md_len+1, GFP_KERNEL); 155 if (mountdata == NULL) { 156 rc = -ENOMEM; 157 goto compose_mount_options_err; 158 } 159 160 /* copy all options except of unc,ip,prefixpath */ 161 off = 0; 162 if (strncmp(sb_mountdata, "sep=", 4) == 0) { 163 sep = sb_mountdata[4]; 164 strncpy(mountdata, sb_mountdata, 5); 165 off += 5; 166 } 167 168 do { 169 tkn_e = strchr(sb_mountdata + off, sep); 170 if (tkn_e == NULL) 171 noff = strlen(sb_mountdata + off); 172 else 173 noff = tkn_e - (sb_mountdata + off) + 1; 174 175 if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) { 176 off += noff; 177 continue; 178 } 179 if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) { 180 off += noff; 181 continue; 182 } 183 if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) { 184 off += noff; 185 continue; 186 } 187 strncat(mountdata, sb_mountdata + off, noff); 188 off += noff; 189 } while (tkn_e); 190 strcat(mountdata, sb_mountdata + off); 191 mountdata[md_len] = '\0'; 192 193 /* copy new IP and ref share name */ 194 if (mountdata[strlen(mountdata) - 1] != sep) 195 strncat(mountdata, &sep, 1); 196 strcat(mountdata, "ip="); 197 strcat(mountdata, srvIP); 198 strncat(mountdata, &sep, 1); 199 strcat(mountdata, "unc="); 200 strcat(mountdata, *devname); 201 202 /* find & copy prefixpath */ 203 tkn_e = strchr(ref->node_name + 2, '\\'); 204 if (tkn_e == NULL) { 205 /* invalid unc, missing share name*/ 206 rc = -EINVAL; 207 goto compose_mount_options_err; 208 } 209 210 tkn_e = strchr(tkn_e + 1, '\\'); 211 if (tkn_e || (strlen(fullpath) - ref->path_consumed)) { 212 strncat(mountdata, &sep, 1); 213 strcat(mountdata, "prefixpath="); 214 if (tkn_e) 215 strcat(mountdata, tkn_e + 1); 216 strcat(mountdata, fullpath + ref->path_consumed); 217 } 218 219 /*cFYI(1, "%s: parent mountdata: %s", __func__,sb_mountdata);*/ 220 /*cFYI(1, "%s: submount mountdata: %s", __func__, mountdata );*/ 221 222compose_mount_options_out: 223 kfree(srvIP); 224 return mountdata; 225 226compose_mount_options_err: 227 kfree(mountdata); 228 mountdata = ERR_PTR(rc); 229 goto compose_mount_options_out; 230} 231 232/** 233 * cifs_dfs_do_refmount - mounts specified path using provided refferal 234 * @cifs_sb: parent/root superblock 235 * @fullpath: full path in UNC format 236 * @ref: server's referral 237 */ 238static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb, 239 const char *fullpath, const struct dfs_info3_param *ref) 240{ 241 struct vfsmount *mnt; 242 char *mountdata; 243 char *devname = NULL; 244 245 /* strip first '\' from fullpath */ 246 mountdata = cifs_compose_mount_options(cifs_sb->mountdata, 247 fullpath + 1, ref, &devname); 248 249 if (IS_ERR(mountdata)) 250 return (struct vfsmount *)mountdata; 251 252 mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata); 253 kfree(mountdata); 254 kfree(devname); 255 return mnt; 256 257} 258 259static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd, 260 struct list_head *mntlist) 261{ 262 /* stolen from afs code */ 263 int err; 264 265 mntget(newmnt); 266 err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist); 267 switch (err) { 268 case 0: 269 path_put(&nd->path); 270 nd->path.mnt = newmnt; 271 nd->path.dentry = dget(newmnt->mnt_root); 272 schedule_delayed_work(&cifs_dfs_automount_task, 273 cifs_dfs_mountpoint_expiry_timeout); 274 break; 275 case -EBUSY: 276 /* someone else made a mount here whilst we were busy */ 277 while (d_mountpoint(nd->path.dentry) && 278 follow_down(&nd->path)) 279 ; 280 err = 0; 281 default: 282 mntput(newmnt); 283 break; 284 } 285 return err; 286} 287 288static void dump_referral(const struct dfs_info3_param *ref) 289{ 290 cFYI(1, "DFS: ref path: %s", ref->path_name); 291 cFYI(1, "DFS: node path: %s", ref->node_name); 292 cFYI(1, "DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type); 293 cFYI(1, "DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag, 294 ref->path_consumed); 295} 296 297 298static void* 299cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd) 300{ 301 struct dfs_info3_param *referrals = NULL; 302 unsigned int num_referrals = 0; 303 struct cifs_sb_info *cifs_sb; 304 struct cifsSesInfo *ses; 305 char *full_path = NULL; 306 int xid, i; 307 int rc = 0; 308 struct vfsmount *mnt = ERR_PTR(-ENOENT); 309 310 cFYI(1, "in %s", __func__); 311 BUG_ON(IS_ROOT(dentry)); 312 313 xid = GetXid(); 314 315 dput(nd->path.dentry); 316 nd->path.dentry = dget(dentry); 317 318 cifs_sb = CIFS_SB(dentry->d_inode->i_sb); 319 ses = cifs_sb->tcon->ses; 320 321 if (!ses) { 322 rc = -EINVAL; 323 goto out_err; 324 } 325 326 /* 327 * The MSDFS spec states that paths in DFS referral requests and 328 * responses must be prefixed by a single '\' character instead of 329 * the double backslashes usually used in the UNC. This function 330 * gives us the latter, so we must adjust the result. 331 */ 332 full_path = build_path_from_dentry(dentry); 333 if (full_path == NULL) { 334 rc = -ENOMEM; 335 goto out_err; 336 } 337 338 rc = get_dfs_path(xid, ses , full_path + 1, cifs_sb->local_nls, 339 &num_referrals, &referrals, 340 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR); 341 342 for (i = 0; i < num_referrals; i++) { 343 int len; 344 dump_referral(referrals+i); 345 /* connect to a node */ 346 len = strlen(referrals[i].node_name); 347 if (len < 2) { 348 cERROR(1, "%s: Net Address path too short: %s", 349 __func__, referrals[i].node_name); 350 rc = -EINVAL; 351 goto out_err; 352 } 353 mnt = cifs_dfs_do_refmount(cifs_sb, 354 full_path, referrals + i); 355 cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__, 356 referrals[i].node_name, mnt); 357 358 /* complete mount procedure if we accured submount */ 359 if (!IS_ERR(mnt)) 360 break; 361 } 362 363 /* we need it cause for() above could exit without valid submount */ 364 rc = PTR_ERR(mnt); 365 if (IS_ERR(mnt)) 366 goto out_err; 367 368 rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list); 369 370out: 371 FreeXid(xid); 372 free_dfs_info_array(referrals, num_referrals); 373 kfree(full_path); 374 cFYI(1, "leaving %s" , __func__); 375 return ERR_PTR(rc); 376out_err: 377 path_put(&nd->path); 378 goto out; 379} 380 381const struct inode_operations cifs_dfs_referral_inode_operations = { 382 .follow_link = cifs_dfs_follow_mountpoint, 383}; 384