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 int nfs_negotiate_security(const struct dentry *parent, 152 const struct dentry *dentry, 153 rpc_authflavor_t *flavor) 154 { 155 struct page *page; 156 struct nfs4_secinfo_flavors *flavors; 157 int (*secinfo)(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *); 158 int ret = -EPERM; 159 160 secinfo = NFS_PROTO(parent->d_inode)->secinfo; 161 if (secinfo != NULL) { 162 page = alloc_page(GFP_KERNEL); 163 if (!page) { 164 ret = -ENOMEM; 165 goto out; 166 } 167 flavors = page_address(page); 168 ret = secinfo(parent->d_inode, &dentry->d_name, flavors); 169 *flavor = nfs_find_best_sec(flavors); 170 put_page(page); 171 } 172 173 out: 174 return ret; 175 } 176 177 static int nfs_lookup_with_sec(struct nfs_server *server, struct dentry *parent, 178 struct dentry *dentry, struct path *path, 179 struct nfs_fh *fh, struct nfs_fattr *fattr, 180 rpc_authflavor_t *flavor) 181 { 182 struct rpc_clnt *clone; 183 struct rpc_auth *auth; 184 int err; 185 186 err = nfs_negotiate_security(parent, path->dentry, flavor); 187 if (err < 0) 188 goto out; 189 clone = rpc_clone_client(server->client); 190 auth = rpcauth_create(*flavor, clone); 191 if (!auth) { 192 err = -EIO; 193 goto out_shutdown; 194 } 195 err = server->nfs_client->rpc_ops->lookup(clone, parent->d_inode, 196 &path->dentry->d_name, 197 fh, fattr); 198 out_shutdown: 199 rpc_shutdown_client(clone); 200 out: 201 return err; 202 } 203 #else /* CONFIG_NFS_V4 */ 204 static inline int nfs_lookup_with_sec(struct nfs_server *server, 205 struct dentry *parent, struct dentry *dentry, 206 struct path *path, struct nfs_fh *fh, 207 struct nfs_fattr *fattr, 208 rpc_authflavor_t *flavor) 209 { 210 return -EPERM; 211 } 212 #endif /* CONFIG_NFS_V4 */ 213 214 /* 215 * nfs_d_automount - Handle crossing a mountpoint on the server 216 * @path - The mountpoint 217 * 218 * When we encounter a mountpoint on the server, we want to set up 219 * a mountpoint on the client too, to prevent inode numbers from 220 * colliding, and to allow "df" to work properly. 221 * On NFSv4, we also want to allow for the fact that different 222 * filesystems may be migrated to different servers in a failover 223 * situation, and that different filesystems may want to use 224 * different security flavours. 225 */ 226 struct vfsmount *nfs_d_automount(struct path *path) 227 { 228 struct vfsmount *mnt; 229 struct nfs_server *server = NFS_SERVER(path->dentry->d_inode); 230 struct dentry *parent; 231 struct nfs_fh *fh = NULL; 232 struct nfs_fattr *fattr = NULL; 233 int err; 234 rpc_authflavor_t flavor = RPC_AUTH_UNIX; 235 236 dprintk("--> nfs_d_automount()\n"); 237 238 mnt = ERR_PTR(-ESTALE); 239 if (IS_ROOT(path->dentry)) 240 goto out_nofree; 241 242 mnt = ERR_PTR(-ENOMEM); 243 fh = nfs_alloc_fhandle(); 244 fattr = nfs_alloc_fattr(); 245 if (fh == NULL || fattr == NULL) 246 goto out; 247 248 dprintk("%s: enter\n", __func__); 249 250 /* Look it up again to get its attributes */ 251 parent = dget_parent(path->dentry); 252 err = server->nfs_client->rpc_ops->lookup(server->client, parent->d_inode, 253 &path->dentry->d_name, 254 fh, fattr); 255 if (err == -EPERM && NFS_PROTO(parent->d_inode)->secinfo != NULL) 256 err = nfs_lookup_with_sec(server, parent, path->dentry, path, fh, fattr, &flavor); 257 dput(parent); 258 if (err != 0) { 259 mnt = ERR_PTR(err); 260 goto out; 261 } 262 263 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) 264 mnt = nfs_do_refmount(path->dentry); 265 else 266 mnt = nfs_do_submount(path->dentry, fh, fattr, flavor); 267 if (IS_ERR(mnt)) 268 goto out; 269 270 dprintk("%s: done, success\n", __func__); 271 mntget(mnt); /* prevent immediate expiration */ 272 mnt_set_expiry(mnt, &nfs_automount_list); 273 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); 274 275 out: 276 nfs_free_fattr(fattr); 277 nfs_free_fhandle(fh); 278 out_nofree: 279 dprintk("<-- nfs_follow_mountpoint() = %p\n", mnt); 280 return mnt; 281 } 282 283 const struct inode_operations nfs_mountpoint_inode_operations = { 284 .getattr = nfs_getattr, 285 }; 286 287 const struct inode_operations nfs_referral_inode_operations = { 288 }; 289 290 static void nfs_expire_automounts(struct work_struct *work) 291 { 292 struct list_head *list = &nfs_automount_list; 293 294 mark_mounts_for_expiry(list); 295 if (!list_empty(list)) 296 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); 297 } 298 299 void nfs_release_automount_timer(void) 300 { 301 if (list_empty(&nfs_automount_list)) 302 cancel_delayed_work(&nfs_automount_task); 303 } 304 305 /* 306 * Clone a mountpoint of the appropriate type 307 */ 308 static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server, 309 const char *devname, 310 struct nfs_clone_mount *mountdata) 311 { 312 #ifdef CONFIG_NFS_V4 313 struct vfsmount *mnt = ERR_PTR(-EINVAL); 314 switch (server->nfs_client->rpc_ops->version) { 315 case 2: 316 case 3: 317 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata); 318 break; 319 case 4: 320 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata); 321 } 322 return mnt; 323 #else 324 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata); 325 #endif 326 } 327 328 /** 329 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary 330 * @dentry - parent directory 331 * @fh - filehandle for new root dentry 332 * @fattr - attributes for new root inode 333 * @authflavor - security flavor to use when performing the mount 334 * 335 */ 336 static struct vfsmount *nfs_do_submount(struct dentry *dentry, 337 struct nfs_fh *fh, 338 struct nfs_fattr *fattr, 339 rpc_authflavor_t authflavor) 340 { 341 struct nfs_clone_mount mountdata = { 342 .sb = dentry->d_sb, 343 .dentry = dentry, 344 .fh = fh, 345 .fattr = fattr, 346 .authflavor = authflavor, 347 }; 348 struct vfsmount *mnt = ERR_PTR(-ENOMEM); 349 char *page = (char *) __get_free_page(GFP_USER); 350 char *devname; 351 352 dprintk("--> nfs_do_submount()\n"); 353 354 dprintk("%s: submounting on %s/%s\n", __func__, 355 dentry->d_parent->d_name.name, 356 dentry->d_name.name); 357 if (page == NULL) 358 goto out; 359 devname = nfs_devname(dentry, page, PAGE_SIZE); 360 mnt = (struct vfsmount *)devname; 361 if (IS_ERR(devname)) 362 goto free_page; 363 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata); 364 free_page: 365 free_page((unsigned long)page); 366 out: 367 dprintk("%s: done\n", __func__); 368 369 dprintk("<-- nfs_do_submount() = %p\n", mnt); 370 return mnt; 371 } 372