fs/nfs/nfs4namespace.c

   1 /*
   2  * linux/fs/nfs/nfs4namespace.c
   3  *
   4  * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
   5  * - Modified by David Howells <dhowells@redhat.com>
   6  *
   7  * NFSv4 namespace
   8  */
   9
  10 #include <linux/dcache.h>
  11 #include <linux/mount.h>
  12 #include <linux/namei.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/vfs.h>
  18 #include <linux/inet.h>
  19 #include "internal.h"
  20 #include "nfs4_fs.h"
  21 #include "dns_resolve.h"
  22
  23 #define NFSDBG_FACILITY         NFSDBG_VFS
  24
  25 /*
  26  * Convert the NFSv4 pathname components into a standard posix path.
  27  *
  28  * Note that the resulting string will be placed at the end of the buffer
  29  */
  30 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  31                                          char *buffer, ssize_t buflen)
  32 {
  33         char *end = buffer + buflen;
  34         int n;
  35
  36         *--end = '\0';
  37         buflen--;
  38
  39         n = pathname->ncomponents;
  40         while (--n >= 0) {
  41                 const struct nfs4_string *component = &pathname->components[n];
  42                 buflen -= component->len + 1;
  43                 if (buflen < 0)
  44                         goto Elong;
  45                 end -= component->len;
  46                 memcpy(end, component->data, component->len);
  47                 *--end = '/';
  48         }
  49         return end;
  50 Elong:
  51         return ERR_PTR(-ENAMETOOLONG);
  52 }
  53
  54 /*
  55  * return the path component of "<server>:<path>"
  56  *  nfspath - the "<server>:<path>" string
  57  *  end - one past the last char that could contain "<server>:"
  58  * returns NULL on failure
  59  */
  60 static char *nfs_path_component(const char *nfspath, const char *end)
  61 {
  62         char *p;
  63
  64         if (*nfspath == '[') {
  65                 /* parse [] escaped IPv6 addrs */
  66                 p = strchr(nfspath, ']');
  67                 if (p != NULL && ++p < end && *p == ':')
  68                         return p + 1;
  69         } else {
  70                 /* otherwise split on first colon */
  71                 p = strchr(nfspath, ':');
  72                 if (p != NULL && p < end)
  73                         return p + 1;
  74         }
  75         return NULL;
  76 }
  77
  78 /*
  79  * Determine the mount path as a string
  80  */
  81 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  82 {
  83         char *limit;
  84         char *path = nfs_path(&limit, dentry, buffer, buflen,
  85                               NFS_PATH_CANONICAL);
  86         if (!IS_ERR(path)) {
  87                 char *path_component = nfs_path_component(path, limit);
  88                 if (path_component)
  89                         return path_component;
  90         }
  91         return path;
  92 }
  93
  94 /*
  95  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  96  * believe to be the server path to this dentry
  97  */
  98 static int nfs4_validate_fspath(struct dentry *dentry,
  99                                 const struct nfs4_fs_locations *locations,
 100                                 char *page, char *page2)
 101 {
 102         const char *path, *fs_path;
 103
 104         path = nfs4_path(dentry, page, PAGE_SIZE);
 105         if (IS_ERR(path))
 106                 return PTR_ERR(path);
 107
 108         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
 109         if (IS_ERR(fs_path))
 110                 return PTR_ERR(fs_path);
 111
 112         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
 113                 dprintk("%s: path %s does not begin with fsroot %s\n",
 114                         __func__, path, fs_path);
 115                 return -ENOENT;
 116         }
 117
 118         return 0;
 119 }
 120
 121 static size_t nfs_parse_server_name(char *string, size_t len,
 122                 struct sockaddr *sa, size_t salen, struct nfs_server *server)
 123 {
 124         struct net *net = rpc_net_ns(server->client);
 125         ssize_t ret;
 126
 127         ret = rpc_pton(net, string, len, sa, salen);
 128         if (ret == 0) {
 129                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
 130                 if (ret < 0)
 131                         ret = 0;
 132         }
 133         return ret;
 134 }
 135
 136 rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
 137 {
 138         struct gss_api_mech *mech;
 139         struct xdr_netobj oid;
 140         int i;
 141         rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
 142
 143         for (i = 0; i < flavors->num_flavors; i++) {
 144                 struct nfs4_secinfo_flavor *flavor;
 145                 flavor = &flavors->flavors[i];
 146
 147                 if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) {
 148                         pseudoflavor = flavor->flavor;
 149                         break;
 150                 } else if (flavor->flavor == RPC_AUTH_GSS) {
 151                         oid.len  = flavor->gss.sec_oid4.len;
 152                         oid.data = flavor->gss.sec_oid4.data;
 153                         mech = gss_mech_get_by_OID(&oid);
 154                         if (!mech)
 155                                 continue;
 156                         pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service);
 157                         gss_mech_put(mech);
 158                         break;
 159                 }
 160         }
 161
 162         return pseudoflavor;
 163 }
 164
 165 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
 166 {
 167         struct page *page;
 168         struct nfs4_secinfo_flavors *flavors;
 169         rpc_authflavor_t flavor;
 170         int err;
 171
 172         page = alloc_page(GFP_KERNEL);
 173         if (!page)
 174                 return -ENOMEM;
 175         flavors = page_address(page);
 176
 177         err = nfs4_proc_secinfo(inode, name, flavors);
 178         if (err < 0) {
 179                 flavor = err;
 180                 goto out;
 181         }
 182
 183         flavor = nfs_find_best_sec(flavors);
 184
 185 out:
 186         put_page(page);
 187         return flavor;
 188 }
 189
 190 /*
 191  * Please call rpc_shutdown_client() when you are done with this client.
 192  */
 193 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 194                                         struct qstr *name)
 195 {
 196         rpc_authflavor_t flavor;
 197
 198         flavor = nfs4_negotiate_security(inode, name);
 199         if ((int)flavor < 0)
 200                 return ERR_PTR((int)flavor);
 201
 202         return rpc_clone_client_set_auth(clnt, flavor);
 203 }
 204
 205 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 206                                      char *page, char *page2,
 207                                      const struct nfs4_fs_location *location)
 208 {
 209         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 210         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 211         char *mnt_path;
 212         unsigned int maxbuflen;
 213         unsigned int s;
 214
 215         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 216         if (IS_ERR(mnt_path))
 217                 return ERR_CAST(mnt_path);
 218         mountdata->mnt_path = mnt_path;
 219         maxbuflen = mnt_path - 1 - page2;
 220
 221         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 222         if (mountdata->addr == NULL)
 223                 return ERR_PTR(-ENOMEM);
 224
 225         for (s = 0; s < location->nservers; s++) {
 226                 const struct nfs4_string *buf = &location->servers[s];
 227
 228                 if (buf->len <= 0 || buf->len >= maxbuflen)
 229                         continue;
 230
 231                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 232                         continue;
 233
 234                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 235                                 mountdata->addr, addr_bufsize,
 236                                 NFS_SB(mountdata->sb));
 237                 if (mountdata->addrlen == 0)
 238                         continue;
 239
 240                 rpc_set_port(mountdata->addr, NFS_PORT);
 241
 242                 memcpy(page2, buf->data, buf->len);
 243                 page2[buf->len] = '\0';
 244                 mountdata->hostname = page2;
 245
 246                 snprintf(page, PAGE_SIZE, "%s:%s",
 247                                 mountdata->hostname,
 248                                 mountdata->mnt_path);
 249
 250                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 251                 if (!IS_ERR(mnt))
 252                         break;
 253         }
 254         kfree(mountdata->addr);
 255         return mnt;
 256 }
 257
 258 /**
 259  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 260  * @dentry - parent directory
 261  * @locations - array of NFSv4 server location information
 262  *
 263  */
 264 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 265                                             const struct nfs4_fs_locations *locations)
 266 {
 267         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 268         struct nfs_clone_mount mountdata = {
 269                 .sb = dentry->d_sb,
 270                 .dentry = dentry,
 271                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 272         };
 273         char *page = NULL, *page2 = NULL;
 274         int loc, error;
 275
 276         if (locations == NULL || locations->nlocations <= 0)
 277                 goto out;
 278
 279         dprintk("%s: referral at %s/%s\n", __func__,
 280                 dentry->d_parent->d_name.name, dentry->d_name.name);
 281
 282         page = (char *) __get_free_page(GFP_USER);
 283         if (!page)
 284                 goto out;
 285
 286         page2 = (char *) __get_free_page(GFP_USER);
 287         if (!page2)
 288                 goto out;
 289
 290         /* Ensure fs path is a prefix of current dentry path */
 291         error = nfs4_validate_fspath(dentry, locations, page, page2);
 292         if (error < 0) {
 293                 mnt = ERR_PTR(error);
 294                 goto out;
 295         }
 296
 297         for (loc = 0; loc < locations->nlocations; loc++) {
 298                 const struct nfs4_fs_location *location = &locations->locations[loc];
 299
 300                 if (location == NULL || location->nservers <= 0 ||
 301                     location->rootpath.ncomponents == 0)
 302                         continue;
 303
 304                 mnt = try_location(&mountdata, page, page2, location);
 305                 if (!IS_ERR(mnt))
 306                         break;
 307         }
 308
 309 out:
 310         free_page((unsigned long) page);
 311         free_page((unsigned long) page2);
 312         dprintk("%s: done\n", __func__);
 313         return mnt;
 314 }
 315
 316 /*
 317  * nfs_do_refmount - handle crossing a referral on server
 318  * @dentry - dentry of referral
 319  *
 320  */
 321 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 322 {
 323         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 324         struct dentry *parent;
 325         struct nfs4_fs_locations *fs_locations = NULL;
 326         struct page *page;
 327         int err;
 328
 329         /* BUG_ON(IS_ROOT(dentry)); */
 330         dprintk("%s: enter\n", __func__);
 331
 332         page = alloc_page(GFP_KERNEL);
 333         if (page == NULL)
 334                 goto out;
 335
 336         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 337         if (fs_locations == NULL)
 338                 goto out_free;
 339
 340         /* Get locations */
 341         mnt = ERR_PTR(-ENOENT);
 342
 343         parent = dget_parent(dentry);
 344         dprintk("%s: getting locations for %s/%s\n",
 345                 __func__, parent->d_name.name, dentry->d_name.name);
 346
 347         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 348         dput(parent);
 349         if (err != 0 ||
 350             fs_locations->nlocations <= 0 ||
 351             fs_locations->fs_path.ncomponents <= 0)
 352                 goto out_free;
 353
 354         mnt = nfs_follow_referral(dentry, fs_locations);
 355 out_free:
 356         __free_page(page);
 357         kfree(fs_locations);
 358 out:
 359         dprintk("%s: done\n", __func__);
 360         return mnt;
 361 }
 362
 363 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 364                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 365 {
 366         struct dentry *parent = dget_parent(dentry);
 367         struct rpc_clnt *client;
 368         struct vfsmount *mnt;
 369
 370         /* Look it up again to get its attributes and sec flavor */
 371         client = nfs4_proc_lookup_mountpoint(parent->d_inode, &dentry->d_name, fh, fattr);
 372         dput(parent);
 373         if (IS_ERR(client))
 374                 return ERR_CAST(client);
 375
 376         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
 377                 mnt = nfs_do_refmount(client, dentry);
 378         else
 379                 mnt = nfs_do_submount(dentry, fh, fattr, client->cl_auth->au_flavor);
 380
 381         rpc_shutdown_client(client);
 382         return mnt;
 383 }