fs/cifs/cifs_dfs_ref.c

   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/vfs.h>
  19 #include <linux/fs.h>
  20 #include "cifsglob.h"
  21 #include "cifsproto.h"
  22 #include "cifsfs.h"
  23 #include "dns_resolve.h"
  24 #include "cifs_debug.h"
  25
  26 static LIST_HEAD(cifs_dfs_automount_list);
  27
  28 static void cifs_dfs_expire_automounts(struct work_struct *work);
  29 static DECLARE_DELAYED_WORK(cifs_dfs_automount_task,
  30                             cifs_dfs_expire_automounts);
  31 static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ;
  32
  33 static void cifs_dfs_expire_automounts(struct work_struct *work)
  34 {
  35         struct list_head *list = &cifs_dfs_automount_list;
  36
  37         mark_mounts_for_expiry(list);
  38         if (!list_empty(list))
  39                 schedule_delayed_work(&cifs_dfs_automount_task,
  40                                       cifs_dfs_mountpoint_expiry_timeout);
  41 }
  42
  43 void cifs_dfs_release_automount_timer(void)
  44 {
  45         BUG_ON(!list_empty(&cifs_dfs_automount_list));
  46         cancel_delayed_work(&cifs_dfs_automount_task);
  47         flush_scheduled_work();
  48 }
  49
  50 /**
  51  * cifs_get_share_name  -       extracts share name from UNC
  52  * @node_name:  pointer to UNC string
  53  *
  54  * Extracts sharename form full UNC.
  55  * i.e. strips from UNC trailing path that is not part of share
  56  * name and fixup missing '\' in the begining of DFS node refferal
  57  * if neccessary.
  58  * Returns pointer to share name on success or NULL on error.
  59  * Caller is responsible for freeing returned string.
  60  */
  61 static char *cifs_get_share_name(const char *node_name)
  62 {
  63         int len;
  64         char *UNC;
  65         char *pSep;
  66
  67         len = strlen(node_name);
  68         UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */,
  69                          GFP_KERNEL);
  70         if (!UNC)
  71                 return NULL;
  72
  73         /* get share name and server name */
  74         if (node_name[1] != '\\') {
  75                 UNC[0] = '\\';
  76                 strncpy(UNC+1, node_name, len);
  77                 len++;
  78                 UNC[len] = 0;
  79         } else {
  80                 strncpy(UNC, node_name, len);
  81                 UNC[len] = 0;
  82         }
  83
  84         /* find server name end */
  85         pSep = memchr(UNC+2, '\\', len-2);
  86         if (!pSep) {
  87                 cERROR(1, ("%s: no server name end in node name: %s",
  88                         __func__, node_name));
  89                 kfree(UNC);
  90                 return NULL;
  91         }
  92
  93         /* find sharename end */
  94         pSep++;
  95         pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC));
  96         if (!pSep) {
  97                 cERROR(1, ("%s:2 cant find share name in node name: %s",
  98                         __func__, node_name));
  99                 kfree(UNC);
 100                 return NULL;
 101         }
 102         /* trim path up to sharename end
 103          *          * now we have share name in UNC */
 104         *pSep = 0;
 105
 106         return UNC;
 107 }
 108
 109
 110 /**
 111  * compose_mount_options        -       creates mount options for refferral
 112  * @sb_mountdata:       parent/root DFS mount options (template)
 113  * @ref_unc:            refferral server UNC
 114  * @devname:            pointer for saving device name
 115  *
 116  * creates mount options for submount based on template options sb_mountdata
 117  * and replacing unc,ip,prefixpath options with ones we've got form ref_unc.
 118  *
 119  * Returns: pointer to new mount options or ERR_PTR.
 120  * Caller is responcible for freeing retunrned value if it is not error.
 121  */
 122 static char *compose_mount_options(const char *sb_mountdata,
 123                                    const char *ref_unc,
 124                                    char **devname)
 125 {
 126         int rc;
 127         char *mountdata;
 128         int md_len;
 129         char *tkn_e;
 130         char *srvIP = NULL;
 131         char sep = ',';
 132         int off, noff;
 133
 134         if (sb_mountdata == NULL)
 135                 return ERR_PTR(-EINVAL);
 136
 137         *devname = cifs_get_share_name(ref_unc);
 138         rc = dns_resolve_server_name_to_ip(*devname, &srvIP);
 139         if (rc != 0) {
 140                 cERROR(1, ("%s: Failed to resolve server part of %s to IP",
 141                           __func__, *devname));
 142                 mountdata = ERR_PTR(rc);
 143                 goto compose_mount_options_out;
 144         }
 145         md_len = strlen(sb_mountdata) + strlen(srvIP) + strlen(ref_unc) + 3;
 146         mountdata = kzalloc(md_len+1, GFP_KERNEL);
 147         if (mountdata == NULL) {
 148                 mountdata = ERR_PTR(-ENOMEM);
 149                 goto compose_mount_options_out;
 150         }
 151
 152         /* copy all options except of unc,ip,prefixpath */
 153         off = 0;
 154         if (strncmp(sb_mountdata, "sep=", 4) == 0) {
 155                         sep = sb_mountdata[4];
 156                         strncpy(mountdata, sb_mountdata, 5);
 157                         off += 5;
 158         }
 159         while ((tkn_e = strchr(sb_mountdata+off, sep))) {
 160                 noff = (tkn_e - (sb_mountdata+off)) + 1;
 161                 if (strnicmp(sb_mountdata+off, "unc=", 4) == 0) {
 162                         off += noff;
 163                         continue;
 164                 }
 165                 if (strnicmp(sb_mountdata+off, "ip=", 3) == 0) {
 166                         off += noff;
 167                         continue;
 168                 }
 169                 if (strnicmp(sb_mountdata+off, "prefixpath=", 3) == 0) {
 170                         off += noff;
 171                         continue;
 172                 }
 173                 strncat(mountdata, sb_mountdata+off, noff);
 174                 off += noff;
 175         }
 176         strcat(mountdata, sb_mountdata+off);
 177         mountdata[md_len] = '\0';
 178
 179         /* copy new IP and ref share name */
 180         strcat(mountdata, ",ip=");
 181         strcat(mountdata, srvIP);
 182         strcat(mountdata, ",unc=");
 183         strcat(mountdata, *devname);
 184
 185         /* find & copy prefixpath */
 186         tkn_e = strchr(ref_unc+2, '\\');
 187         if (tkn_e) {
 188                 tkn_e = strchr(tkn_e+1, '\\');
 189                 if (tkn_e) {
 190                         strcat(mountdata, ",prefixpath=");
 191                         strcat(mountdata, tkn_e);
 192                 }
 193         }
 194
 195         /*cFYI(1,("%s: parent mountdata: %s", __func__,sb_mountdata));*/
 196         /*cFYI(1, ("%s: submount mountdata: %s", __func__, mountdata ));*/
 197
 198 compose_mount_options_out:
 199         kfree(srvIP);
 200         return mountdata;
 201 }
 202
 203
 204 static struct vfsmount *cifs_dfs_do_refmount(const struct vfsmount *mnt_parent,
 205                 struct dentry *dentry, char *ref_unc)
 206 {
 207         struct cifs_sb_info *cifs_sb;
 208         struct vfsmount *mnt;
 209         char *mountdata;
 210         char *devname = NULL;
 211
 212         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
 213         mountdata = compose_mount_options(cifs_sb->mountdata,
 214                                                 ref_unc, &devname);
 215
 216         if (IS_ERR(mountdata))
 217                 return (struct vfsmount *)mountdata;
 218
 219         mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata);
 220         kfree(mountdata);
 221         kfree(devname);
 222         return mnt;
 223
 224 }
 225
 226 static char *build_full_dfs_path_from_dentry(struct dentry *dentry)
 227 {
 228         char *full_path = NULL;
 229         char *search_path;
 230         char *tmp_path;
 231         size_t l_max_len;
 232         struct cifs_sb_info *cifs_sb;
 233
 234         if (dentry->d_inode == NULL)
 235                 return NULL;
 236
 237         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
 238
 239         if (cifs_sb->tcon == NULL)
 240                 return NULL;
 241
 242         search_path = build_path_from_dentry(dentry);
 243         if (search_path == NULL)
 244                 return NULL;
 245
 246         if (cifs_sb->tcon->Flags & SMB_SHARE_IS_IN_DFS) {
 247                 /* we should use full path name to correct working with DFS */
 248                 l_max_len = strnlen(cifs_sb->tcon->treeName, MAX_TREE_SIZE+1) +
 249                                         strnlen(search_path, MAX_PATHCONF) + 1;
 250                 tmp_path = kmalloc(l_max_len, GFP_KERNEL);
 251                 if (tmp_path == NULL) {
 252                         kfree(search_path);
 253                         return NULL;
 254                 }
 255                 strncpy(tmp_path, cifs_sb->tcon->treeName, l_max_len);
 256                 strcat(tmp_path, search_path);
 257                 tmp_path[l_max_len-1] = 0;
 258                 full_path = tmp_path;
 259                 kfree(search_path);
 260         } else {
 261                 full_path = search_path;
 262         }
 263         return full_path;
 264 }
 265
 266 static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
 267                                 struct list_head *mntlist)
 268 {
 269         /* stolen from afs code */
 270         int err;
 271
 272         mntget(newmnt);
 273         err = do_add_mount(newmnt, nd, nd->path.mnt->mnt_flags, mntlist);
 274         switch (err) {
 275         case 0:
 276                 path_put(&nd->path);
 277                 nd->path.mnt = newmnt;
 278                 nd->path.dentry = dget(newmnt->mnt_root);
 279                 schedule_delayed_work(&cifs_dfs_automount_task,
 280                                       cifs_dfs_mountpoint_expiry_timeout);
 281                 break;
 282         case -EBUSY:
 283                 /* someone else made a mount here whilst we were busy */
 284                 while (d_mountpoint(nd->path.dentry) &&
 285                        follow_down(&nd->path.mnt, &nd->path.dentry))
 286                         ;
 287                 err = 0;
 288         default:
 289                 mntput(newmnt);
 290                 break;
 291         }
 292         return err;
 293 }
 294
 295 static void dump_referral(const struct dfs_info3_param *ref)
 296 {
 297         cFYI(1, ("DFS: ref path: %s", ref->path_name));
 298         cFYI(1, ("DFS: node path: %s", ref->node_name));
 299         cFYI(1, ("DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type));
 300         cFYI(1, ("DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag,
 301                                 ref->path_consumed));
 302 }
 303
 304
 305 static void*
 306 cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 307 {
 308         struct dfs_info3_param *referrals = NULL;
 309         unsigned int num_referrals = 0;
 310         struct cifs_sb_info *cifs_sb;
 311         struct cifsSesInfo *ses;
 312         char *full_path = NULL;
 313         int xid, i;
 314         int rc = 0;
 315         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 316
 317         cFYI(1, ("in %s", __func__));
 318         BUG_ON(IS_ROOT(dentry));
 319
 320         xid = GetXid();
 321
 322         dput(nd->path.dentry);
 323         nd->path.dentry = dget(dentry);
 324
 325         cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
 326         ses = cifs_sb->tcon->ses;
 327
 328         if (!ses) {
 329                 rc = -EINVAL;
 330                 goto out_err;
 331         }
 332
 333         full_path = build_full_dfs_path_from_dentry(dentry);
 334         if (full_path == NULL) {
 335                 rc = -ENOMEM;
 336                 goto out_err;
 337         }
 338
 339         rc = get_dfs_path(xid, ses , full_path, cifs_sb->local_nls,
 340                 &num_referrals, &referrals,
 341                 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
 342
 343         for (i = 0; i < num_referrals; i++) {
 344                 dump_referral(referrals+i);
 345                 /* connect to a storage node */
 346                 if (referrals[i].flags & DFSREF_STORAGE_SERVER) {
 347                         int len;
 348                         len = strlen(referrals[i].node_name);
 349                         if (len < 2) {
 350                                 cERROR(1, ("%s: Net Address path too short: %s",
 351                                         __func__, referrals[i].node_name));
 352                                 rc = -EINVAL;
 353                                 goto out_err;
 354                         }
 355                         mnt = cifs_dfs_do_refmount(nd->path.mnt,
 356                                                 nd->path.dentry,
 357                                                 referrals[i].node_name);
 358                         cFYI(1, ("%s: cifs_dfs_do_refmount:%s , mnt:%p",
 359                                          __func__,
 360                                         referrals[i].node_name, mnt));
 361
 362                         /* complete mount procedure if we accured submount */
 363                         if (!IS_ERR(mnt))
 364                                 break;
 365                 }
 366         }
 367
 368         /* we need it cause for() above could exit without valid submount */
 369         rc = PTR_ERR(mnt);
 370         if (IS_ERR(mnt))
 371                 goto out_err;
 372
 373         nd->path.mnt->mnt_flags |= MNT_SHRINKABLE;
 374         rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
 375
 376 out:
 377         FreeXid(xid);
 378         free_dfs_info_array(referrals, num_referrals);
 379         kfree(full_path);
 380         cFYI(1, ("leaving %s" , __func__));
 381         return ERR_PTR(rc);
 382 out_err:
 383         path_put(&nd->path);
 384         goto out;
 385 }
 386
 387 struct inode_operations cifs_dfs_referral_inode_operations = {
 388         .follow_link = cifs_dfs_follow_mountpoint,
 389 };
 390