fs/nfs/getroot.c

   1 /* getroot.c: get the root dentry for an NFS mount
   2  *
   3  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/config.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15
  16 #include <linux/time.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/string.h>
  20 #include <linux/stat.h>
  21 #include <linux/errno.h>
  22 #include <linux/unistd.h>
  23 #include <linux/sunrpc/clnt.h>
  24 #include <linux/sunrpc/stats.h>
  25 #include <linux/nfs_fs.h>
  26 #include <linux/nfs_mount.h>
  27 #include <linux/nfs4_mount.h>
  28 #include <linux/lockd/bind.h>
  29 #include <linux/smp_lock.h>
  30 #include <linux/seq_file.h>
  31 #include <linux/mount.h>
  32 #include <linux/nfs_idmap.h>
  33 #include <linux/vfs.h>
  34 #include <linux/namei.h>
  35 #include <linux/namespace.h>
  36 #include <linux/security.h>
  37
  38 #include <asm/system.h>
  39 #include <asm/uaccess.h>
  40
  41 #include "nfs4_fs.h"
  42 #include "delegation.h"
  43 #include "internal.h"
  44
  45 #define NFSDBG_FACILITY         NFSDBG_CLIENT
  46 #define NFS_PARANOIA 1
  47
  48 /*
  49  * get an NFS2/NFS3 root dentry from the root filehandle
  50  */
  51 struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
  52 {
  53         struct nfs_server *server = NFS_SB(sb);
  54         struct nfs_fsinfo fsinfo;
  55         struct nfs_fattr fattr;
  56         struct dentry *mntroot;
  57         struct inode *inode;
  58         int error;
  59
  60         /* create a dummy root dentry with dummy inode for this superblock */
  61         if (!sb->s_root) {
  62                 struct nfs_fh dummyfh;
  63                 struct dentry *root;
  64                 struct inode *iroot;
  65
  66                 memset(&dummyfh, 0, sizeof(dummyfh));
  67                 memset(&fattr, 0, sizeof(fattr));
  68                 nfs_fattr_init(&fattr);
  69                 fattr.valid = NFS_ATTR_FATTR;
  70                 fattr.type = NFDIR;
  71                 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR;
  72                 fattr.nlink = 2;
  73
  74                 iroot = nfs_fhget(sb, &dummyfh, &fattr);
  75                 if (IS_ERR(iroot))
  76                         return ERR_PTR(PTR_ERR(iroot));
  77
  78                 root = d_alloc_root(iroot);
  79                 if (!root) {
  80                         iput(iroot);
  81                         return ERR_PTR(-ENOMEM);
  82                 }
  83
  84                 sb->s_root = root;
  85         }
  86
  87         /* get the actual root for this mount */
  88         fsinfo.fattr = &fattr;
  89
  90         error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
  91         if (error < 0) {
  92                 dprintk("nfs_get_root: getattr error = %d\n", -error);
  93                 return ERR_PTR(error);
  94         }
  95
  96         inode = nfs_fhget(sb, mntfh, fsinfo.fattr);
  97         if (IS_ERR(inode)) {
  98                 dprintk("nfs_get_root: get root inode failed\n");
  99                 return ERR_PTR(PTR_ERR(inode));
 100         }
 101
 102         /* root dentries normally start off anonymous and get spliced in later
 103          * if the dentry tree reaches them; however if the dentry already
 104          * exists, we'll pick it up at this point and use it as the root
 105          */
 106         mntroot = d_alloc_anon(inode);
 107         if (!mntroot) {
 108                 iput(inode);
 109                 dprintk("nfs_get_root: get root dentry failed\n");
 110                 return ERR_PTR(-ENOMEM);
 111         }
 112
 113         security_d_instantiate(mntroot, inode);
 114
 115         if (!mntroot->d_op)
 116                 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
 117
 118         return mntroot;
 119 }
 120
 121 #ifdef CONFIG_NFS_V4
 122
 123 /*
 124  * Do a simple pathwalk from the root FH of the server to the nominated target
 125  * of the mountpoint
 126  * - give error on symlinks
 127  * - give error on ".." occurring in the path
 128  * - follow traversals
 129  */
 130 int nfs4_path_walk(struct nfs_server *server,
 131                    struct nfs_fh *mntfh,
 132                    const char *path)
 133 {
 134         struct nfs_fsinfo fsinfo;
 135         struct nfs_fattr fattr;
 136         struct nfs_fh lastfh;
 137         struct qstr name;
 138         int ret;
 139         //int referral_count = 0;
 140
 141         dprintk("--> nfs4_path_walk(,,%s)\n", path);
 142
 143         fsinfo.fattr = &fattr;
 144         nfs_fattr_init(&fattr);
 145
 146         if (*path++ != '/') {
 147                 dprintk("nfs4_get_root: Path does not begin with a slash\n");
 148                 return -EINVAL;
 149         }
 150
 151         /* Start by getting the root filehandle from the server */
 152         ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
 153         if (ret < 0) {
 154                 dprintk("nfs4_get_root: getroot error = %d\n", -ret);
 155                 return ret;
 156         }
 157
 158         if (fattr.type != NFDIR) {
 159                 printk(KERN_ERR "nfs4_get_root:"
 160                        " getroot encountered non-directory\n");
 161                 return -ENOTDIR;
 162         }
 163
 164         if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 165                 printk(KERN_ERR "nfs4_get_root:"
 166                        " getroot obtained referral\n");
 167                 return -EREMOTE;
 168         }
 169
 170 next_component:
 171         dprintk("Next: %s\n", path);
 172
 173         /* extract the next bit of the path */
 174         if (!*path)
 175                 goto path_walk_complete;
 176
 177         name.name = path;
 178         while (*path && *path != '/')
 179                 path++;
 180         name.len = path - (const char *) name.name;
 181
 182 eat_dot_dir:
 183         while (*path == '/')
 184                 path++;
 185
 186         if (path[0] == '.' && (path[1] == '/' || !path[1])) {
 187                 path += 2;
 188                 goto eat_dot_dir;
 189         }
 190
 191         if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2])
 192             ) {
 193                 printk(KERN_ERR "nfs4_get_root:"
 194                        " Mount path contains reference to \"..\"\n");
 195                 return -EINVAL;
 196         }
 197
 198         /* lookup the next FH in the sequence */
 199         memcpy(&lastfh, mntfh, sizeof(lastfh));
 200
 201         dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path);
 202
 203         ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name,
 204                                                     mntfh, &fattr);
 205         if (ret < 0) {
 206                 dprintk("nfs4_get_root: getroot error = %d\n", -ret);
 207                 return ret;
 208         }
 209
 210         if (fattr.type != NFDIR) {
 211                 printk(KERN_ERR "nfs4_get_root:"
 212                        " lookupfh encountered non-directory\n");
 213                 return -ENOTDIR;
 214         }
 215
 216         if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 217                 printk(KERN_ERR "nfs4_get_root:"
 218                        " lookupfh obtained referral\n");
 219                 return -EREMOTE;
 220         }
 221
 222         goto next_component;
 223
 224 path_walk_complete:
 225         memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid));
 226         dprintk("<-- nfs4_path_walk() = 0\n");
 227         return 0;
 228 }
 229
 230 /*
 231  * get an NFS4 root dentry from the root filehandle
 232  */
 233 struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
 234 {
 235         struct nfs_server *server = NFS_SB(sb);
 236         struct nfs_fattr fattr;
 237         struct dentry *mntroot;
 238         struct inode *inode;
 239         int error;
 240
 241         dprintk("--> nfs4_get_root()\n");
 242
 243         /* create a dummy root dentry with dummy inode for this superblock */
 244         if (!sb->s_root) {
 245                 struct nfs_fh dummyfh;
 246                 struct dentry *root;
 247                 struct inode *iroot;
 248
 249                 memset(&dummyfh, 0, sizeof(dummyfh));
 250                 memset(&fattr, 0, sizeof(fattr));
 251                 nfs_fattr_init(&fattr);
 252                 fattr.valid = NFS_ATTR_FATTR;
 253                 fattr.type = NFDIR;
 254                 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR;
 255                 fattr.nlink = 2;
 256
 257                 iroot = nfs_fhget(sb, &dummyfh, &fattr);
 258                 if (IS_ERR(iroot))
 259                         return ERR_PTR(PTR_ERR(iroot));
 260
 261                 root = d_alloc_root(iroot);
 262                 if (!root) {
 263                         iput(iroot);
 264                         return ERR_PTR(-ENOMEM);
 265                 }
 266
 267                 sb->s_root = root;
 268         }
 269
 270         /* get the info about the server and filesystem */
 271         error = nfs4_server_capabilities(server, mntfh);
 272         if (error < 0) {
 273                 dprintk("nfs_get_root: getcaps error = %d\n",
 274                         -error);
 275                 return ERR_PTR(error);
 276         }
 277
 278         /* get the actual root for this mount */
 279         error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr);
 280         if (error < 0) {
 281                 dprintk("nfs_get_root: getattr error = %d\n", -error);
 282                 return ERR_PTR(error);
 283         }
 284
 285         inode = nfs_fhget(sb, mntfh, &fattr);
 286         if (IS_ERR(inode)) {
 287                 dprintk("nfs_get_root: get root inode failed\n");
 288                 return ERR_PTR(PTR_ERR(inode));
 289         }
 290
 291         /* root dentries normally start off anonymous and get spliced in later
 292          * if the dentry tree reaches them; however if the dentry already
 293          * exists, we'll pick it up at this point and use it as the root
 294          */
 295         mntroot = d_alloc_anon(inode);
 296         if (!mntroot) {
 297                 iput(inode);
 298                 dprintk("nfs_get_root: get root dentry failed\n");
 299                 return ERR_PTR(-ENOMEM);
 300         }
 301
 302         security_d_instantiate(mntroot, inode);
 303
 304         if (!mntroot->d_op)
 305                 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
 306
 307         dprintk("<-- nfs4_get_root()\n");
 308         return mntroot;
 309 }
 310
 311 #endif /* CONFIG_NFS_V4 */