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/module.h> 13 #include <linux/init.h> 14 15 #include <linux/time.h> 16 #include <linux/kernel.h> 17 #include <linux/mm.h> 18 #include <linux/string.h> 19 #include <linux/stat.h> 20 #include <linux/errno.h> 21 #include <linux/unistd.h> 22 #include <linux/sunrpc/clnt.h> 23 #include <linux/sunrpc/stats.h> 24 #include <linux/nfs_fs.h> 25 #include <linux/nfs_mount.h> 26 #include <linux/nfs4_mount.h> 27 #include <linux/lockd/bind.h> 28 #include <linux/seq_file.h> 29 #include <linux/mount.h> 30 #include <linux/nfs_idmap.h> 31 #include <linux/vfs.h> 32 #include <linux/namei.h> 33 #include <linux/mnt_namespace.h> 34 #include <linux/security.h> 35 36 #include <asm/system.h> 37 #include <asm/uaccess.h> 38 39 #include "nfs4_fs.h" 40 #include "delegation.h" 41 #include "internal.h" 42 43 #define NFSDBG_FACILITY NFSDBG_CLIENT 44 45 /* 46 * get an NFS2/NFS3 root dentry from the root filehandle 47 */ 48 struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh) 49 { 50 struct nfs_server *server = NFS_SB(sb); 51 struct nfs_fsinfo fsinfo; 52 struct nfs_fattr fattr; 53 struct dentry *mntroot; 54 struct inode *inode; 55 int error; 56 57 /* create a dummy root dentry with dummy inode for this superblock */ 58 if (!sb->s_root) { 59 struct nfs_fh dummyfh; 60 struct dentry *root; 61 struct inode *iroot; 62 63 memset(&dummyfh, 0, sizeof(dummyfh)); 64 memset(&fattr, 0, sizeof(fattr)); 65 nfs_fattr_init(&fattr); 66 fattr.valid = NFS_ATTR_FATTR; 67 fattr.type = NFDIR; 68 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR; 69 fattr.nlink = 2; 70 71 iroot = nfs_fhget(sb, &dummyfh, &fattr); 72 if (IS_ERR(iroot)) 73 return ERR_PTR(PTR_ERR(iroot)); 74 75 root = d_alloc_root(iroot); 76 if (!root) { 77 iput(iroot); 78 return ERR_PTR(-ENOMEM); 79 } 80 81 sb->s_root = root; 82 } 83 84 /* get the actual root for this mount */ 85 fsinfo.fattr = &fattr; 86 87 error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 88 if (error < 0) { 89 dprintk("nfs_get_root: getattr error = %d\n", -error); 90 return ERR_PTR(error); 91 } 92 93 inode = nfs_fhget(sb, mntfh, fsinfo.fattr); 94 if (IS_ERR(inode)) { 95 dprintk("nfs_get_root: get root inode failed\n"); 96 return ERR_PTR(PTR_ERR(inode)); 97 } 98 99 /* root dentries normally start off anonymous and get spliced in later 100 * if the dentry tree reaches them; however if the dentry already 101 * exists, we'll pick it up at this point and use it as the root 102 */ 103 mntroot = d_alloc_anon(inode); 104 if (!mntroot) { 105 iput(inode); 106 dprintk("nfs_get_root: get root dentry failed\n"); 107 return ERR_PTR(-ENOMEM); 108 } 109 110 security_d_instantiate(mntroot, inode); 111 112 if (!mntroot->d_op) 113 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 114 115 return mntroot; 116 } 117 118 #ifdef CONFIG_NFS_V4 119 120 /* 121 * Do a simple pathwalk from the root FH of the server to the nominated target 122 * of the mountpoint 123 * - give error on symlinks 124 * - give error on ".." occurring in the path 125 * - follow traversals 126 */ 127 int nfs4_path_walk(struct nfs_server *server, 128 struct nfs_fh *mntfh, 129 const char *path) 130 { 131 struct nfs_fsinfo fsinfo; 132 struct nfs_fattr fattr; 133 struct nfs_fh lastfh; 134 struct qstr name; 135 int ret; 136 137 dprintk("--> nfs4_path_walk(,,%s)\n", path); 138 139 fsinfo.fattr = &fattr; 140 nfs_fattr_init(&fattr); 141 142 /* Eat leading slashes */ 143 while (*path == '/') 144 path++; 145 146 /* Start by getting the root filehandle from the server */ 147 ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 148 if (ret < 0) { 149 dprintk("nfs4_get_root: getroot error = %d\n", -ret); 150 return ret; 151 } 152 153 if (fattr.type != NFDIR) { 154 printk(KERN_ERR "nfs4_get_root:" 155 " getroot encountered non-directory\n"); 156 return -ENOTDIR; 157 } 158 159 /* FIXME: It is quite valid for the server to return a referral here */ 160 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { 161 printk(KERN_ERR "nfs4_get_root:" 162 " getroot obtained referral\n"); 163 return -EREMOTE; 164 } 165 166 next_component: 167 dprintk("Next: %s\n", path); 168 169 /* extract the next bit of the path */ 170 if (!*path) 171 goto path_walk_complete; 172 173 name.name = path; 174 while (*path && *path != '/') 175 path++; 176 name.len = path - (const char *) name.name; 177 178 if (name.len > NFS4_MAXNAMLEN) 179 return -ENAMETOOLONG; 180 181 eat_dot_dir: 182 while (*path == '/') 183 path++; 184 185 if (path[0] == '.' && (path[1] == '/' || !path[1])) { 186 path += 2; 187 goto eat_dot_dir; 188 } 189 190 /* FIXME: Why shouldn't the user be able to use ".." in the path? */ 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 /* FIXME: Referrals are quite valid here too */ 217 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { 218 printk(KERN_ERR "nfs4_get_root:" 219 " lookupfh obtained referral\n"); 220 return -EREMOTE; 221 } 222 223 goto next_component; 224 225 path_walk_complete: 226 memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid)); 227 dprintk("<-- nfs4_path_walk() = 0\n"); 228 return 0; 229 } 230 231 /* 232 * get an NFS4 root dentry from the root filehandle 233 */ 234 struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) 235 { 236 struct nfs_server *server = NFS_SB(sb); 237 struct nfs_fattr fattr; 238 struct dentry *mntroot; 239 struct inode *inode; 240 int error; 241 242 dprintk("--> nfs4_get_root()\n"); 243 244 /* create a dummy root dentry with dummy inode for this superblock */ 245 if (!sb->s_root) { 246 struct nfs_fh dummyfh; 247 struct dentry *root; 248 struct inode *iroot; 249 250 memset(&dummyfh, 0, sizeof(dummyfh)); 251 memset(&fattr, 0, sizeof(fattr)); 252 nfs_fattr_init(&fattr); 253 fattr.valid = NFS_ATTR_FATTR; 254 fattr.type = NFDIR; 255 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR; 256 fattr.nlink = 2; 257 258 iroot = nfs_fhget(sb, &dummyfh, &fattr); 259 if (IS_ERR(iroot)) 260 return ERR_PTR(PTR_ERR(iroot)); 261 262 root = d_alloc_root(iroot); 263 if (!root) { 264 iput(iroot); 265 return ERR_PTR(-ENOMEM); 266 } 267 268 sb->s_root = root; 269 } 270 271 /* get the info about the server and filesystem */ 272 error = nfs4_server_capabilities(server, mntfh); 273 if (error < 0) { 274 dprintk("nfs_get_root: getcaps error = %d\n", 275 -error); 276 return ERR_PTR(error); 277 } 278 279 /* get the actual root for this mount */ 280 error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr); 281 if (error < 0) { 282 dprintk("nfs_get_root: getattr error = %d\n", -error); 283 return ERR_PTR(error); 284 } 285 286 inode = nfs_fhget(sb, mntfh, &fattr); 287 if (IS_ERR(inode)) { 288 dprintk("nfs_get_root: get root inode failed\n"); 289 return ERR_PTR(PTR_ERR(inode)); 290 } 291 292 /* root dentries normally start off anonymous and get spliced in later 293 * if the dentry tree reaches them; however if the dentry already 294 * exists, we'll pick it up at this point and use it as the root 295 */ 296 mntroot = d_alloc_anon(inode); 297 if (!mntroot) { 298 iput(inode); 299 dprintk("nfs_get_root: get root dentry failed\n"); 300 return ERR_PTR(-ENOMEM); 301 } 302 303 security_d_instantiate(mntroot, inode); 304 305 if (!mntroot->d_op) 306 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 307 308 dprintk("<-- nfs4_get_root()\n"); 309 return mntroot; 310 } 311 312 #endif /* CONFIG_NFS_V4 */ 313