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