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 eat_dot_dir: 179 while (*path == '/') 180 path++; 181 182 if (path[0] == '.' && (path[1] == '/' || !path[1])) { 183 path += 2; 184 goto eat_dot_dir; 185 } 186 187 /* FIXME: Why shouldn't the user be able to use ".." in the path? */ 188 if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2]) 189 ) { 190 printk(KERN_ERR "nfs4_get_root:" 191 " Mount path contains reference to \"..\"\n"); 192 return -EINVAL; 193 } 194 195 /* lookup the next FH in the sequence */ 196 memcpy(&lastfh, mntfh, sizeof(lastfh)); 197 198 dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path); 199 200 ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name, 201 mntfh, &fattr); 202 if (ret < 0) { 203 dprintk("nfs4_get_root: getroot error = %d\n", -ret); 204 return ret; 205 } 206 207 if (fattr.type != NFDIR) { 208 printk(KERN_ERR "nfs4_get_root:" 209 " lookupfh encountered non-directory\n"); 210 return -ENOTDIR; 211 } 212 213 /* FIXME: Referrals are quite valid here too */ 214 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { 215 printk(KERN_ERR "nfs4_get_root:" 216 " lookupfh obtained referral\n"); 217 return -EREMOTE; 218 } 219 220 goto next_component; 221 222 path_walk_complete: 223 memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid)); 224 dprintk("<-- nfs4_path_walk() = 0\n"); 225 return 0; 226 } 227 228 /* 229 * get an NFS4 root dentry from the root filehandle 230 */ 231 struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) 232 { 233 struct nfs_server *server = NFS_SB(sb); 234 struct nfs_fattr fattr; 235 struct dentry *mntroot; 236 struct inode *inode; 237 int error; 238 239 dprintk("--> nfs4_get_root()\n"); 240 241 /* create a dummy root dentry with dummy inode for this superblock */ 242 if (!sb->s_root) { 243 struct nfs_fh dummyfh; 244 struct dentry *root; 245 struct inode *iroot; 246 247 memset(&dummyfh, 0, sizeof(dummyfh)); 248 memset(&fattr, 0, sizeof(fattr)); 249 nfs_fattr_init(&fattr); 250 fattr.valid = NFS_ATTR_FATTR; 251 fattr.type = NFDIR; 252 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR; 253 fattr.nlink = 2; 254 255 iroot = nfs_fhget(sb, &dummyfh, &fattr); 256 if (IS_ERR(iroot)) 257 return ERR_PTR(PTR_ERR(iroot)); 258 259 root = d_alloc_root(iroot); 260 if (!root) { 261 iput(iroot); 262 return ERR_PTR(-ENOMEM); 263 } 264 265 sb->s_root = root; 266 } 267 268 /* get the info about the server and filesystem */ 269 error = nfs4_server_capabilities(server, mntfh); 270 if (error < 0) { 271 dprintk("nfs_get_root: getcaps error = %d\n", 272 -error); 273 return ERR_PTR(error); 274 } 275 276 /* get the actual root for this mount */ 277 error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr); 278 if (error < 0) { 279 dprintk("nfs_get_root: getattr error = %d\n", -error); 280 return ERR_PTR(error); 281 } 282 283 inode = nfs_fhget(sb, mntfh, &fattr); 284 if (IS_ERR(inode)) { 285 dprintk("nfs_get_root: get root inode failed\n"); 286 return ERR_PTR(PTR_ERR(inode)); 287 } 288 289 /* root dentries normally start off anonymous and get spliced in later 290 * if the dentry tree reaches them; however if the dentry already 291 * exists, we'll pick it up at this point and use it as the root 292 */ 293 mntroot = d_alloc_anon(inode); 294 if (!mntroot) { 295 iput(inode); 296 dprintk("nfs_get_root: get root dentry failed\n"); 297 return ERR_PTR(-ENOMEM); 298 } 299 300 security_d_instantiate(mntroot, inode); 301 302 if (!mntroot->d_op) 303 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 304 305 dprintk("<-- nfs4_get_root()\n"); 306 return mntroot; 307 } 308 309 #endif /* CONFIG_NFS_V4 */ 310