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 rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
 138 {
 139         struct gss_api_mech *mech;
 140         struct xdr_netobj oid;
 141         int i;
 142         rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
 143
 144         for (i = 0; i < flavors->num_flavors; i++) {
 145                 struct nfs4_secinfo_flavor *flavor;
 146                 flavor = &flavors->flavors[i];
 147
 148                 if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) {
 149                         pseudoflavor = flavor->flavor;
 150                         break;
 151                 } else if (flavor->flavor == RPC_AUTH_GSS) {
 152                         oid.len  = flavor->gss.sec_oid4.len;
 153                         oid.data = flavor->gss.sec_oid4.data;
 154                         mech = gss_mech_get_by_OID(&oid);
 155                         if (!mech)
 156                                 continue;
 157                         pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service);
 158                         gss_mech_put(mech);
 159                         break;
 160                 }
 161         }
 162
 163         return pseudoflavor;
 164 }
 165
 166 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
 167 {
 168         struct page *page;
 169         struct nfs4_secinfo_flavors *flavors;
 170         rpc_authflavor_t flavor;
 171         int err;
 172
 173         page = alloc_page(GFP_KERNEL);
 174         if (!page)
 175                 return -ENOMEM;
 176         flavors = page_address(page);
 177
 178         err = nfs4_proc_secinfo(inode, name, flavors);
 179         if (err < 0) {
 180                 flavor = err;
 181                 goto out;
 182         }
 183
 184         flavor = nfs_find_best_sec(flavors);
 185
 186 out:
 187         put_page(page);
 188         return flavor;
 189 }
 190
 191 /*
 192  * Please call rpc_shutdown_client() when you are done with this client.
 193  */
 194 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 195                                         struct qstr *name)
 196 {
 197         rpc_authflavor_t flavor;
 198
 199         flavor = nfs4_negotiate_security(inode, name);
 200         if ((int)flavor < 0)
 201                 return ERR_PTR((int)flavor);
 202
 203         return rpc_clone_client_set_auth(clnt, flavor);
 204 }
 205
 206 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 207                                      char *page, char *page2,
 208                                      const struct nfs4_fs_location *location)
 209 {
 210         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 211         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 212         char *mnt_path;
 213         unsigned int maxbuflen;
 214         unsigned int s;
 215
 216         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 217         if (IS_ERR(mnt_path))
 218                 return ERR_CAST(mnt_path);
 219         mountdata->mnt_path = mnt_path;
 220         maxbuflen = mnt_path - 1 - page2;
 221
 222         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 223         if (mountdata->addr == NULL)
 224                 return ERR_PTR(-ENOMEM);
 225
 226         for (s = 0; s < location->nservers; s++) {
 227                 const struct nfs4_string *buf = &location->servers[s];
 228
 229                 if (buf->len <= 0 || buf->len >= maxbuflen)
 230                         continue;
 231
 232                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 233                         continue;
 234
 235                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 236                                 mountdata->addr, addr_bufsize,
 237                                 NFS_SB(mountdata->sb));
 238                 if (mountdata->addrlen == 0)
 239                         continue;
 240
 241                 rpc_set_port(mountdata->addr, NFS_PORT);
 242
 243                 memcpy(page2, buf->data, buf->len);
 244                 page2[buf->len] = '\0';
 245                 mountdata->hostname = page2;
 246
 247                 snprintf(page, PAGE_SIZE, "%s:%s",
 248                                 mountdata->hostname,
 249                                 mountdata->mnt_path);
 250
 251                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 252                 if (!IS_ERR(mnt))
 253                         break;
 254         }
 255         kfree(mountdata->addr);
 256         return mnt;
 257 }
 258
 259 /**
 260  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 261  * @dentry - parent directory
 262  * @locations - array of NFSv4 server location information
 263  *
 264  */
 265 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 266                                             const struct nfs4_fs_locations *locations)
 267 {
 268         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 269         struct nfs_clone_mount mountdata = {
 270                 .sb = dentry->d_sb,
 271                 .dentry = dentry,
 272                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 273         };
 274         char *page = NULL, *page2 = NULL;
 275         int loc, error;
 276
 277         if (locations == NULL || locations->nlocations <= 0)
 278                 goto out;
 279
 280         dprintk("%s: referral at %s/%s\n", __func__,
 281                 dentry->d_parent->d_name.name, dentry->d_name.name);
 282
 283         page = (char *) __get_free_page(GFP_USER);
 284         if (!page)
 285                 goto out;
 286
 287         page2 = (char *) __get_free_page(GFP_USER);
 288         if (!page2)
 289                 goto out;
 290
 291         /* Ensure fs path is a prefix of current dentry path */
 292         error = nfs4_validate_fspath(dentry, locations, page, page2);
 293         if (error < 0) {
 294                 mnt = ERR_PTR(error);
 295                 goto out;
 296         }
 297
 298         for (loc = 0; loc < locations->nlocations; loc++) {
 299                 const struct nfs4_fs_location *location = &locations->locations[loc];
 300
 301                 if (location == NULL || location->nservers <= 0 ||
 302                     location->rootpath.ncomponents == 0)
 303                         continue;
 304
 305                 mnt = try_location(&mountdata, page, page2, location);
 306                 if (!IS_ERR(mnt))
 307                         break;
 308         }
 309
 310 out:
 311         free_page((unsigned long) page);
 312         free_page((unsigned long) page2);
 313         dprintk("%s: done\n", __func__);
 314         return mnt;
 315 }
 316
 317 /*
 318  * nfs_do_refmount - handle crossing a referral on server
 319  * @dentry - dentry of referral
 320  *
 321  */
 322 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 323 {
 324         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 325         struct dentry *parent;
 326         struct nfs4_fs_locations *fs_locations = NULL;
 327         struct page *page;
 328         int err;
 329
 330         /* BUG_ON(IS_ROOT(dentry)); */
 331         dprintk("%s: enter\n", __func__);
 332
 333         page = alloc_page(GFP_KERNEL);
 334         if (page == NULL)
 335                 goto out;
 336
 337         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 338         if (fs_locations == NULL)
 339                 goto out_free;
 340
 341         /* Get locations */
 342         mnt = ERR_PTR(-ENOENT);
 343
 344         parent = dget_parent(dentry);
 345         dprintk("%s: getting locations for %s/%s\n",
 346                 __func__, parent->d_name.name, dentry->d_name.name);
 347
 348         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 349         dput(parent);
 350         if (err != 0 ||
 351             fs_locations->nlocations <= 0 ||
 352             fs_locations->fs_path.ncomponents <= 0)
 353                 goto out_free;
 354
 355         mnt = nfs_follow_referral(dentry, fs_locations);
 356 out_free:
 357         __free_page(page);
 358         kfree(fs_locations);
 359 out:
 360         dprintk("%s: done\n", __func__);
 361         return mnt;
 362 }
 363
 364 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 365                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 366 {
 367         struct dentry *parent = dget_parent(dentry);
 368         struct rpc_clnt *client;
 369         struct vfsmount *mnt;
 370
 371         /* Look it up again to get its attributes and sec flavor */
 372         client = nfs4_proc_lookup_mountpoint(parent->d_inode, &dentry->d_name, fh, fattr);
 373         dput(parent);
 374         if (IS_ERR(client))
 375                 return ERR_CAST(client);
 376
 377         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
 378                 mnt = nfs_do_refmount(client, dentry);
 379         else
 380                 mnt = nfs_do_submount(dentry, fh, fattr, client->cl_auth->au_flavor);
 381
 382         rpc_shutdown_client(client);
 383         return mnt;
 384 }