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/nfs_mount.h>
  15 #include <linux/slab.h>
  16 #include <linux/string.h>
  17 #include <linux/sunrpc/clnt.h>
  18 #include <linux/sunrpc/addr.h>
  19 #include <linux/vfs.h>
  20 #include <linux/inet.h>
  21 #include "internal.h"
  22 #include "nfs4_fs.h"
  23 #include "dns_resolve.h"
  24
  25 #define NFSDBG_FACILITY         NFSDBG_VFS
  26
  27 /*
  28  * Convert the NFSv4 pathname components into a standard posix path.
  29  *
  30  * Note that the resulting string will be placed at the end of the buffer
  31  */
  32 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  33                                          char *buffer, ssize_t buflen)
  34 {
  35         char *end = buffer + buflen;
  36         int n;
  37
  38         *--end = '\0';
  39         buflen--;
  40
  41         n = pathname->ncomponents;
  42         while (--n >= 0) {
  43                 const struct nfs4_string *component = &pathname->components[n];
  44                 buflen -= component->len + 1;
  45                 if (buflen < 0)
  46                         goto Elong;
  47                 end -= component->len;
  48                 memcpy(end, component->data, component->len);
  49                 *--end = '/';
  50         }
  51         return end;
  52 Elong:
  53         return ERR_PTR(-ENAMETOOLONG);
  54 }
  55
  56 /*
  57  * return the path component of "<server>:<path>"
  58  *  nfspath - the "<server>:<path>" string
  59  *  end - one past the last char that could contain "<server>:"
  60  * returns NULL on failure
  61  */
  62 static char *nfs_path_component(const char *nfspath, const char *end)
  63 {
  64         char *p;
  65
  66         if (*nfspath == '[') {
  67                 /* parse [] escaped IPv6 addrs */
  68                 p = strchr(nfspath, ']');
  69                 if (p != NULL && ++p < end && *p == ':')
  70                         return p + 1;
  71         } else {
  72                 /* otherwise split on first colon */
  73                 p = strchr(nfspath, ':');
  74                 if (p != NULL && p < end)
  75                         return p + 1;
  76         }
  77         return NULL;
  78 }
  79
  80 /*
  81  * Determine the mount path as a string
  82  */
  83 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  84 {
  85         char *limit;
  86         char *path = nfs_path(&limit, dentry, buffer, buflen,
  87                               NFS_PATH_CANONICAL);
  88         if (!IS_ERR(path)) {
  89                 char *path_component = nfs_path_component(path, limit);
  90                 if (path_component)
  91                         return path_component;
  92         }
  93         return path;
  94 }
  95
  96 /*
  97  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  98  * believe to be the server path to this dentry
  99  */
 100 static int nfs4_validate_fspath(struct dentry *dentry,
 101                                 const struct nfs4_fs_locations *locations,
 102                                 char *page, char *page2)
 103 {
 104         const char *path, *fs_path;
 105
 106         path = nfs4_path(dentry, page, PAGE_SIZE);
 107         if (IS_ERR(path))
 108                 return PTR_ERR(path);
 109
 110         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
 111         if (IS_ERR(fs_path))
 112                 return PTR_ERR(fs_path);
 113
 114         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
 115                 dprintk("%s: path %s does not begin with fsroot %s\n",
 116                         __func__, path, fs_path);
 117                 return -ENOENT;
 118         }
 119
 120         return 0;
 121 }
 122
 123 static size_t nfs_parse_server_name(char *string, size_t len,
 124                 struct sockaddr *sa, size_t salen, struct nfs_server *server)
 125 {
 126         struct net *net = rpc_net_ns(server->client);
 127         ssize_t ret;
 128
 129         ret = rpc_pton(net, string, len, sa, salen);
 130         if (ret == 0) {
 131                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
 132                 if (ret < 0)
 133                         ret = 0;
 134         }
 135         return ret;
 136 }
 137
 138 /**
 139  * nfs_find_best_sec - Find a security mechanism supported locally
 140  * @flavors: List of security tuples returned by SECINFO procedure
 141  *
 142  * Return the pseudoflavor of the first security mechanism in
 143  * "flavors" that is locally supported.  Return RPC_AUTH_UNIX if
 144  * no matching flavor is found in the array.  The "flavors" array
 145  * is searched in the order returned from the server, per RFC 3530
 146  * recommendation.
 147  */
 148 rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
 149 {
 150         rpc_authflavor_t pseudoflavor;
 151         struct nfs4_secinfo4 *secinfo;
 152         unsigned int i;
 153
 154         for (i = 0; i < flavors->num_flavors; i++) {
 155                 secinfo = &flavors->flavors[i];
 156
 157                 switch (secinfo->flavor) {
 158                 case RPC_AUTH_NULL:
 159                 case RPC_AUTH_UNIX:
 160                 case RPC_AUTH_GSS:
 161                         pseudoflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
 162                                                         &secinfo->flavor_info);
 163                         if (pseudoflavor != RPC_AUTH_MAXFLAVOR)
 164                                 return pseudoflavor;
 165                         break;
 166                 }
 167         }
 168
 169         return RPC_AUTH_UNIX;
 170 }
 171
 172 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
 173 {
 174         struct page *page;
 175         struct nfs4_secinfo_flavors *flavors;
 176         rpc_authflavor_t flavor;
 177         int err;
 178
 179         page = alloc_page(GFP_KERNEL);
 180         if (!page)
 181                 return -ENOMEM;
 182         flavors = page_address(page);
 183
 184         err = nfs4_proc_secinfo(inode, name, flavors);
 185         if (err < 0) {
 186                 flavor = err;
 187                 goto out;
 188         }
 189
 190         flavor = nfs_find_best_sec(flavors);
 191
 192 out:
 193         put_page(page);
 194         return flavor;
 195 }
 196
 197 /*
 198  * Please call rpc_shutdown_client() when you are done with this client.
 199  */
 200 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 201                                         struct qstr *name)
 202 {
 203         rpc_authflavor_t flavor;
 204
 205         flavor = nfs4_negotiate_security(inode, name);
 206         if ((int)flavor < 0)
 207                 return ERR_PTR((int)flavor);
 208
 209         return rpc_clone_client_set_auth(clnt, flavor);
 210 }
 211
 212 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 213                                      char *page, char *page2,
 214                                      const struct nfs4_fs_location *location)
 215 {
 216         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 217         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 218         char *mnt_path;
 219         unsigned int maxbuflen;
 220         unsigned int s;
 221
 222         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 223         if (IS_ERR(mnt_path))
 224                 return ERR_CAST(mnt_path);
 225         mountdata->mnt_path = mnt_path;
 226         maxbuflen = mnt_path - 1 - page2;
 227
 228         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 229         if (mountdata->addr == NULL)
 230                 return ERR_PTR(-ENOMEM);
 231
 232         for (s = 0; s < location->nservers; s++) {
 233                 const struct nfs4_string *buf = &location->servers[s];
 234
 235                 if (buf->len <= 0 || buf->len >= maxbuflen)
 236                         continue;
 237
 238                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 239                         continue;
 240
 241                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 242                                 mountdata->addr, addr_bufsize,
 243                                 NFS_SB(mountdata->sb));
 244                 if (mountdata->addrlen == 0)
 245                         continue;
 246
 247                 rpc_set_port(mountdata->addr, NFS_PORT);
 248
 249                 memcpy(page2, buf->data, buf->len);
 250                 page2[buf->len] = '\0';
 251                 mountdata->hostname = page2;
 252
 253                 snprintf(page, PAGE_SIZE, "%s:%s",
 254                                 mountdata->hostname,
 255                                 mountdata->mnt_path);
 256
 257                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 258                 if (!IS_ERR(mnt))
 259                         break;
 260         }
 261         kfree(mountdata->addr);
 262         return mnt;
 263 }
 264
 265 /**
 266  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 267  * @dentry - parent directory
 268  * @locations - array of NFSv4 server location information
 269  *
 270  */
 271 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 272                                             const struct nfs4_fs_locations *locations)
 273 {
 274         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 275         struct nfs_clone_mount mountdata = {
 276                 .sb = dentry->d_sb,
 277                 .dentry = dentry,
 278                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 279         };
 280         char *page = NULL, *page2 = NULL;
 281         int loc, error;
 282
 283         if (locations == NULL || locations->nlocations <= 0)
 284                 goto out;
 285
 286         dprintk("%s: referral at %s/%s\n", __func__,
 287                 dentry->d_parent->d_name.name, dentry->d_name.name);
 288
 289         page = (char *) __get_free_page(GFP_USER);
 290         if (!page)
 291                 goto out;
 292
 293         page2 = (char *) __get_free_page(GFP_USER);
 294         if (!page2)
 295                 goto out;
 296
 297         /* Ensure fs path is a prefix of current dentry path */
 298         error = nfs4_validate_fspath(dentry, locations, page, page2);
 299         if (error < 0) {
 300                 mnt = ERR_PTR(error);
 301                 goto out;
 302         }
 303
 304         for (loc = 0; loc < locations->nlocations; loc++) {
 305                 const struct nfs4_fs_location *location = &locations->locations[loc];
 306
 307                 if (location == NULL || location->nservers <= 0 ||
 308                     location->rootpath.ncomponents == 0)
 309                         continue;
 310
 311                 mnt = try_location(&mountdata, page, page2, location);
 312                 if (!IS_ERR(mnt))
 313                         break;
 314         }
 315
 316 out:
 317         free_page((unsigned long) page);
 318         free_page((unsigned long) page2);
 319         dprintk("%s: done\n", __func__);
 320         return mnt;
 321 }
 322
 323 /*
 324  * nfs_do_refmount - handle crossing a referral on server
 325  * @dentry - dentry of referral
 326  *
 327  */
 328 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 329 {
 330         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 331         struct dentry *parent;
 332         struct nfs4_fs_locations *fs_locations = NULL;
 333         struct page *page;
 334         int err;
 335
 336         /* BUG_ON(IS_ROOT(dentry)); */
 337         dprintk("%s: enter\n", __func__);
 338
 339         page = alloc_page(GFP_KERNEL);
 340         if (page == NULL)
 341                 goto out;
 342
 343         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 344         if (fs_locations == NULL)
 345                 goto out_free;
 346
 347         /* Get locations */
 348         mnt = ERR_PTR(-ENOENT);
 349
 350         parent = dget_parent(dentry);
 351         dprintk("%s: getting locations for %s/%s\n",
 352                 __func__, parent->d_name.name, dentry->d_name.name);
 353
 354         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 355         dput(parent);
 356         if (err != 0 ||
 357             fs_locations->nlocations <= 0 ||
 358             fs_locations->fs_path.ncomponents <= 0)
 359                 goto out_free;
 360
 361         mnt = nfs_follow_referral(dentry, fs_locations);
 362 out_free:
 363         __free_page(page);
 364         kfree(fs_locations);
 365 out:
 366         dprintk("%s: done\n", __func__);
 367         return mnt;
 368 }
 369
 370 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 371                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 372 {
 373         rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
 374         struct dentry *parent = dget_parent(dentry);
 375         struct inode *dir = parent->d_inode;
 376         struct qstr *name = &dentry->d_name;
 377         struct rpc_clnt *client;
 378         struct vfsmount *mnt;
 379
 380         /* Look it up again to get its attributes and sec flavor */
 381         client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
 382         dput(parent);
 383         if (IS_ERR(client))
 384                 return ERR_CAST(client);
 385
 386         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
 387                 mnt = nfs_do_refmount(client, dentry);
 388                 goto out;
 389         }
 390
 391         if (client->cl_auth->au_flavor != flavor)
 392                 flavor = client->cl_auth->au_flavor;
 393         else if (!(server->flags & NFS_MOUNT_SECFLAVOUR)) {
 394                 rpc_authflavor_t new = nfs4_negotiate_security(dir, name);
 395                 if ((int)new >= 0)
 396                         flavor = new;
 397         }
 398         mnt = nfs_do_submount(dentry, fh, fattr, flavor);
 399 out:
 400         rpc_shutdown_client(client);
 401         return mnt;
 402 }