1 /* 2 * linux/fs/nfs/namespace.c 3 * 4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com> 5 * - Modified by David Howells <dhowells@redhat.com> 6 * 7 * NFS namespace 8 */ 9 10 #include <linux/dcache.h> 11 #include <linux/gfp.h> 12 #include <linux/mount.h> 13 #include <linux/namei.h> 14 #include <linux/nfs_fs.h> 15 #include <linux/string.h> 16 #include <linux/sunrpc/clnt.h> 17 #include <linux/vfs.h> 18 #include <linux/sunrpc/gss_api.h> 19 #include "internal.h" 20 21 #define NFSDBG_FACILITY NFSDBG_VFS 22 23 static void nfs_expire_automounts(struct work_struct *work); 24 25 static LIST_HEAD(nfs_automount_list); 26 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts); 27 int nfs_mountpoint_expiry_timeout = 500 * HZ; 28 29 static struct vfsmount *nfs_do_submount(struct dentry *dentry, 30 struct nfs_fh *fh, 31 struct nfs_fattr *fattr, 32 rpc_authflavor_t authflavor); 33 34 /* 35 * nfs_path - reconstruct the path given an arbitrary dentry 36 * @base - used to return pointer to the end of devname part of path 37 * @dentry - pointer to dentry 38 * @buffer - result buffer 39 * @buflen - length of buffer 40 * 41 * Helper function for constructing the server pathname 42 * by arbitrary hashed dentry. 43 * 44 * This is mainly for use in figuring out the path on the 45 * server side when automounting on top of an existing partition 46 * and in generating /proc/mounts and friends. 47 */ 48 char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen) 49 { 50 char *end; 51 int namelen; 52 unsigned seq; 53 const char *base; 54 55 rename_retry: 56 end = buffer+buflen; 57 *--end = '\0'; 58 buflen--; 59 60 seq = read_seqbegin(&rename_lock); 61 rcu_read_lock(); 62 while (1) { 63 spin_lock(&dentry->d_lock); 64 if (IS_ROOT(dentry)) 65 break; 66 namelen = dentry->d_name.len; 67 buflen -= namelen + 1; 68 if (buflen < 0) 69 goto Elong_unlock; 70 end -= namelen; 71 memcpy(end, dentry->d_name.name, namelen); 72 *--end = '/'; 73 spin_unlock(&dentry->d_lock); 74 dentry = dentry->d_parent; 75 } 76 if (read_seqretry(&rename_lock, seq)) { 77 spin_unlock(&dentry->d_lock); 78 rcu_read_unlock(); 79 goto rename_retry; 80 } 81 if (*end != '/') { 82 if (--buflen < 0) { 83 spin_unlock(&dentry->d_lock); 84 rcu_read_unlock(); 85 goto Elong; 86 } 87 *--end = '/'; 88 } 89 *p = end; 90 base = dentry->d_fsdata; 91 if (!base) { 92 spin_unlock(&dentry->d_lock); 93 rcu_read_unlock(); 94 WARN_ON(1); 95 return end; 96 } 97 namelen = strlen(base); 98 /* Strip off excess slashes in base string */ 99 while (namelen > 0 && base[namelen - 1] == '/') 100 namelen--; 101 buflen -= namelen; 102 if (buflen < 0) { 103 spin_unlock(&dentry->d_lock); 104 rcu_read_unlock(); 105 goto Elong; 106 } 107 end -= namelen; 108 memcpy(end, base, namelen); 109 spin_unlock(&dentry->d_lock); 110 rcu_read_unlock(); 111 return end; 112 Elong_unlock: 113 spin_unlock(&dentry->d_lock); 114 rcu_read_unlock(); 115 if (read_seqretry(&rename_lock, seq)) 116 goto rename_retry; 117 Elong: 118 return ERR_PTR(-ENAMETOOLONG); 119 } 120 121 #ifdef CONFIG_NFS_V4 122 rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors) 123 { 124 struct gss_api_mech *mech; 125 struct xdr_netobj oid; 126 int i; 127 rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX; 128 129 for (i = 0; i < flavors->num_flavors; i++) { 130 struct nfs4_secinfo_flavor *flavor; 131 flavor = &flavors->flavors[i]; 132 133 if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) { 134 pseudoflavor = flavor->flavor; 135 break; 136 } else if (flavor->flavor == RPC_AUTH_GSS) { 137 oid.len = flavor->gss.sec_oid4.len; 138 oid.data = flavor->gss.sec_oid4.data; 139 mech = gss_mech_get_by_OID(&oid); 140 if (!mech) 141 continue; 142 pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service); 143 gss_mech_put(mech); 144 break; 145 } 146 } 147 148 return pseudoflavor; 149 } 150 151 static struct rpc_clnt *nfs_lookup_mountpoint(struct inode *dir, 152 struct qstr *name, 153 struct nfs_fh *fh, 154 struct nfs_fattr *fattr) 155 { 156 int err; 157 158 if (NFS_PROTO(dir)->version == 4) 159 return nfs4_proc_lookup_mountpoint(dir, name, fh, fattr); 160 161 err = NFS_PROTO(dir)->lookup(NFS_SERVER(dir)->client, dir, name, fh, fattr); 162 if (err) 163 return ERR_PTR(err); 164 return rpc_clone_client(NFS_SERVER(dir)->client); 165 } 166 #else /* CONFIG_NFS_V4 */ 167 static inline struct rpc_clnt *nfs_lookup_mountpoint(struct inode *dir, 168 struct qstr *name, 169 struct nfs_fh *fh, 170 struct nfs_fattr *fattr) 171 { 172 int err = NFS_PROTO(dir)->lookup(NFS_SERVER(dir)->client, dir, name, fh, fattr); 173 if (err) 174 return ERR_PTR(err); 175 return rpc_clone_client(NFS_SERVER(dir)->client); 176 } 177 #endif /* CONFIG_NFS_V4 */ 178 179 /* 180 * nfs_d_automount - Handle crossing a mountpoint on the server 181 * @path - The mountpoint 182 * 183 * When we encounter a mountpoint on the server, we want to set up 184 * a mountpoint on the client too, to prevent inode numbers from 185 * colliding, and to allow "df" to work properly. 186 * On NFSv4, we also want to allow for the fact that different 187 * filesystems may be migrated to different servers in a failover 188 * situation, and that different filesystems may want to use 189 * different security flavours. 190 */ 191 struct vfsmount *nfs_d_automount(struct path *path) 192 { 193 struct vfsmount *mnt; 194 struct dentry *parent; 195 struct nfs_fh *fh = NULL; 196 struct nfs_fattr *fattr = NULL; 197 struct rpc_clnt *client; 198 199 dprintk("--> nfs_d_automount()\n"); 200 201 mnt = ERR_PTR(-ESTALE); 202 if (IS_ROOT(path->dentry)) 203 goto out_nofree; 204 205 mnt = ERR_PTR(-ENOMEM); 206 fh = nfs_alloc_fhandle(); 207 fattr = nfs_alloc_fattr(); 208 if (fh == NULL || fattr == NULL) 209 goto out; 210 211 dprintk("%s: enter\n", __func__); 212 213 /* Look it up again to get its attributes */ 214 parent = dget_parent(path->dentry); 215 client = nfs_lookup_mountpoint(parent->d_inode, &path->dentry->d_name, fh, fattr); 216 dput(parent); 217 if (IS_ERR(client)) { 218 mnt = ERR_CAST(client); 219 goto out; 220 } 221 222 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) 223 mnt = nfs_do_refmount(client, path->dentry); 224 else 225 mnt = nfs_do_submount(path->dentry, fh, fattr, client->cl_auth->au_flavor); 226 rpc_shutdown_client(client); 227 228 if (IS_ERR(mnt)) 229 goto out; 230 231 dprintk("%s: done, success\n", __func__); 232 mntget(mnt); /* prevent immediate expiration */ 233 mnt_set_expiry(mnt, &nfs_automount_list); 234 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); 235 236 out: 237 nfs_free_fattr(fattr); 238 nfs_free_fhandle(fh); 239 out_nofree: 240 if (IS_ERR(mnt)) 241 dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt)); 242 else 243 dprintk("<-- %s() = %p\n", __func__, mnt); 244 return mnt; 245 } 246 247 const struct inode_operations nfs_mountpoint_inode_operations = { 248 .getattr = nfs_getattr, 249 }; 250 251 const struct inode_operations nfs_referral_inode_operations = { 252 }; 253 254 static void nfs_expire_automounts(struct work_struct *work) 255 { 256 struct list_head *list = &nfs_automount_list; 257 258 mark_mounts_for_expiry(list); 259 if (!list_empty(list)) 260 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); 261 } 262 263 void nfs_release_automount_timer(void) 264 { 265 if (list_empty(&nfs_automount_list)) 266 cancel_delayed_work(&nfs_automount_task); 267 } 268 269 /* 270 * Clone a mountpoint of the appropriate type 271 */ 272 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server, 273 const char *devname, 274 struct nfs_clone_mount *mountdata) 275 { 276 #ifdef CONFIG_NFS_V4 277 struct vfsmount *mnt = ERR_PTR(-EINVAL); 278 switch (server->nfs_client->rpc_ops->version) { 279 case 2: 280 case 3: 281 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata); 282 break; 283 case 4: 284 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata); 285 } 286 return mnt; 287 #else 288 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata); 289 #endif 290 } 291 292 /** 293 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary 294 * @dentry - parent directory 295 * @fh - filehandle for new root dentry 296 * @fattr - attributes for new root inode 297 * @authflavor - security flavor to use when performing the mount 298 * 299 */ 300 static struct vfsmount *nfs_do_submount(struct dentry *dentry, 301 struct nfs_fh *fh, 302 struct nfs_fattr *fattr, 303 rpc_authflavor_t authflavor) 304 { 305 struct nfs_clone_mount mountdata = { 306 .sb = dentry->d_sb, 307 .dentry = dentry, 308 .fh = fh, 309 .fattr = fattr, 310 .authflavor = authflavor, 311 }; 312 struct vfsmount *mnt = ERR_PTR(-ENOMEM); 313 char *page = (char *) __get_free_page(GFP_USER); 314 char *devname; 315 316 dprintk("--> nfs_do_submount()\n"); 317 318 dprintk("%s: submounting on %s/%s\n", __func__, 319 dentry->d_parent->d_name.name, 320 dentry->d_name.name); 321 if (page == NULL) 322 goto out; 323 devname = nfs_devname(dentry, page, PAGE_SIZE); 324 mnt = (struct vfsmount *)devname; 325 if (IS_ERR(devname)) 326 goto free_page; 327 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata); 328 free_page: 329 free_page((unsigned long)page); 330 out: 331 dprintk("%s: done\n", __func__); 332 333 dprintk("<-- nfs_do_submount() = %p\n", mnt); 334 return mnt; 335 } 336