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         if (!IS_ERR(path)) {
  86                 char *path_component = nfs_path_component(path, limit);
  87                 if (path_component)
  88                         return path_component;
  89         }
  90         return path;
  91 }
  92
  93 /*
  94  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
  95  * believe to be the server path to this dentry
  96  */
  97 static int nfs4_validate_fspath(struct dentry *dentry,
  98                                 const struct nfs4_fs_locations *locations,
  99                                 char *page, char *page2)
 100 {
 101         const char *path, *fs_path;
 102
 103         path = nfs4_path(dentry, page, PAGE_SIZE);
 104         if (IS_ERR(path))
 105                 return PTR_ERR(path);
 106
 107         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
 108         if (IS_ERR(fs_path))
 109                 return PTR_ERR(fs_path);
 110
 111         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
 112                 dprintk("%s: path %s does not begin with fsroot %s\n",
 113                         __func__, path, fs_path);
 114                 return -ENOENT;
 115         }
 116
 117         return 0;
 118 }
 119
 120 static size_t nfs_parse_server_name(char *string, size_t len,
 121                 struct sockaddr *sa, size_t salen, struct nfs_server *server)
 122 {
 123         struct net *net = rpc_net_ns(server->client);
 124         ssize_t ret;
 125
 126         ret = rpc_pton(net, string, len, sa, salen);
 127         if (ret == 0) {
 128                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
 129                 if (ret < 0)
 130                         ret = 0;
 131         }
 132         return ret;
 133 }
 134
 135 rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
 136 {
 137         struct gss_api_mech *mech;
 138         struct xdr_netobj oid;
 139         int i;
 140         rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
 141
 142         for (i = 0; i < flavors->num_flavors; i++) {
 143                 struct nfs4_secinfo_flavor *flavor;
 144                 flavor = &flavors->flavors[i];
 145
 146                 if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) {
 147                         pseudoflavor = flavor->flavor;
 148                         break;
 149                 } else if (flavor->flavor == RPC_AUTH_GSS) {
 150                         oid.len  = flavor->gss.sec_oid4.len;
 151                         oid.data = flavor->gss.sec_oid4.data;
 152                         mech = gss_mech_get_by_OID(&oid);
 153                         if (!mech)
 154                                 continue;
 155                         pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service);
 156                         gss_mech_put(mech);
 157                         break;
 158                 }
 159         }
 160
 161         return pseudoflavor;
 162 }
 163
 164 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
 165 {
 166         struct page *page;
 167         struct nfs4_secinfo_flavors *flavors;
 168         rpc_authflavor_t flavor;
 169         int err;
 170
 171         page = alloc_page(GFP_KERNEL);
 172         if (!page)
 173                 return -ENOMEM;
 174         flavors = page_address(page);
 175
 176         err = nfs4_proc_secinfo(inode, name, flavors);
 177         if (err < 0) {
 178                 flavor = err;
 179                 goto out;
 180         }
 181
 182         flavor = nfs_find_best_sec(flavors);
 183
 184 out:
 185         put_page(page);
 186         return flavor;
 187 }
 188
 189 /*
 190  * Please call rpc_shutdown_client() when you are done with this client.
 191  */
 192 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 193                                         struct qstr *name)
 194 {
 195         rpc_authflavor_t flavor;
 196
 197         flavor = nfs4_negotiate_security(inode, name);
 198         if ((int)flavor < 0)
 199                 return ERR_PTR((int)flavor);
 200
 201         return rpc_clone_client_set_auth(clnt, flavor);
 202 }
 203
 204 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 205                                      char *page, char *page2,
 206                                      const struct nfs4_fs_location *location)
 207 {
 208         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 209         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 210         char *mnt_path;
 211         unsigned int maxbuflen;
 212         unsigned int s;
 213
 214         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 215         if (IS_ERR(mnt_path))
 216                 return ERR_CAST(mnt_path);
 217         mountdata->mnt_path = mnt_path;
 218         maxbuflen = mnt_path - 1 - page2;
 219
 220         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 221         if (mountdata->addr == NULL)
 222                 return ERR_PTR(-ENOMEM);
 223
 224         for (s = 0; s < location->nservers; s++) {
 225                 const struct nfs4_string *buf = &location->servers[s];
 226
 227                 if (buf->len <= 0 || buf->len >= maxbuflen)
 228                         continue;
 229
 230                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 231                         continue;
 232
 233                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 234                                 mountdata->addr, addr_bufsize,
 235                                 NFS_SB(mountdata->sb));
 236                 if (mountdata->addrlen == 0)
 237                         continue;
 238
 239                 rpc_set_port(mountdata->addr, NFS_PORT);
 240
 241                 memcpy(page2, buf->data, buf->len);
 242                 page2[buf->len] = '\0';
 243                 mountdata->hostname = page2;
 244
 245                 snprintf(page, PAGE_SIZE, "%s:%s",
 246                                 mountdata->hostname,
 247                                 mountdata->mnt_path);
 248
 249                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 250                 if (!IS_ERR(mnt))
 251                         break;
 252         }
 253         kfree(mountdata->addr);
 254         return mnt;
 255 }
 256
 257 /**
 258  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 259  * @dentry - parent directory
 260  * @locations - array of NFSv4 server location information
 261  *
 262  */
 263 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 264                                             const struct nfs4_fs_locations *locations)
 265 {
 266         struct vfsmount *mnt = ERR_PTR(-ENOENT);
 267         struct nfs_clone_mount mountdata = {
 268                 .sb = dentry->d_sb,
 269                 .dentry = dentry,
 270                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 271         };
 272         char *page = NULL, *page2 = NULL;
 273         int loc, error;
 274
 275         if (locations == NULL || locations->nlocations <= 0)
 276                 goto out;
 277
 278         dprintk("%s: referral at %s/%s\n", __func__,
 279                 dentry->d_parent->d_name.name, dentry->d_name.name);
 280
 281         page = (char *) __get_free_page(GFP_USER);
 282         if (!page)
 283                 goto out;
 284
 285         page2 = (char *) __get_free_page(GFP_USER);
 286         if (!page2)
 287                 goto out;
 288
 289         /* Ensure fs path is a prefix of current dentry path */
 290         error = nfs4_validate_fspath(dentry, locations, page, page2);
 291         if (error < 0) {
 292                 mnt = ERR_PTR(error);
 293                 goto out;
 294         }
 295
 296         for (loc = 0; loc < locations->nlocations; loc++) {
 297                 const struct nfs4_fs_location *location = &locations->locations[loc];
 298
 299                 if (location == NULL || location->nservers <= 0 ||
 300                     location->rootpath.ncomponents == 0)
 301                         continue;
 302
 303                 mnt = try_location(&mountdata, page, page2, location);
 304                 if (!IS_ERR(mnt))
 305                         break;
 306         }
 307
 308 out:
 309         free_page((unsigned long) page);
 310         free_page((unsigned long) page2);
 311         dprintk("%s: done\n", __func__);
 312         return mnt;
 313 }
 314
 315 /*
 316  * nfs_do_refmount - handle crossing a referral on server
 317  * @dentry - dentry of referral
 318  *
 319  */
 320 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 321 {
 322         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 323         struct dentry *parent;
 324         struct nfs4_fs_locations *fs_locations = NULL;
 325         struct page *page;
 326         int err;
 327
 328         /* BUG_ON(IS_ROOT(dentry)); */
 329         dprintk("%s: enter\n", __func__);
 330
 331         page = alloc_page(GFP_KERNEL);
 332         if (page == NULL)
 333                 goto out;
 334
 335         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 336         if (fs_locations == NULL)
 337                 goto out_free;
 338
 339         /* Get locations */
 340         mnt = ERR_PTR(-ENOENT);
 341
 342         parent = dget_parent(dentry);
 343         dprintk("%s: getting locations for %s/%s\n",
 344                 __func__, parent->d_name.name, dentry->d_name.name);
 345
 346         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 347         dput(parent);
 348         if (err != 0 ||
 349             fs_locations->nlocations <= 0 ||
 350             fs_locations->fs_path.ncomponents <= 0)
 351                 goto out_free;
 352
 353         mnt = nfs_follow_referral(dentry, fs_locations);
 354 out_free:
 355         __free_page(page);
 356         kfree(fs_locations);
 357 out:
 358         dprintk("%s: done\n", __func__);
 359         return mnt;
 360 }
 361
 362 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 363                                struct nfs_fh *fh, struct nfs_fattr *fattr)
 364 {
 365         struct dentry *parent = dget_parent(dentry);
 366         struct rpc_clnt *client;
 367         struct vfsmount *mnt;
 368
 369         /* Look it up again to get its attributes and sec flavor */
 370         client = nfs4_proc_lookup_mountpoint(parent->d_inode, &dentry->d_name, fh, fattr);
 371         dput(parent);
 372         if (IS_ERR(client))
 373                 return ERR_CAST(client);
 374
 375         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
 376                 mnt = nfs_do_refmount(client, dentry);
 377         else
 378                 mnt = nfs_do_submount(dentry, fh, fattr, client->cl_auth->au_flavor);
 379
 380         rpc_shutdown_client(client);
 381         return mnt;
 382 }