linux/fs/nfs/nfs4namespace.c
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   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 */
  30static 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;
  50Elong:
  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 */
  60static 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 */
  81static 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 */
  98static 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
 121static 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
 136rpc_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
 165static 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
 185out:
 186        put_page(page);
 187        return flavor;
 188}
 189
 190/*
 191 * Please call rpc_shutdown_client() when you are done with this client.
 192 */
 193struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 194                                        struct qstr *name)
 195{
 196        struct rpc_clnt *clone;
 197        struct rpc_auth *auth;
 198        rpc_authflavor_t flavor;
 199
 200        flavor = nfs4_negotiate_security(inode, name);
 201        if ((int)flavor < 0)
 202                return ERR_PTR(flavor);
 203
 204        clone = rpc_clone_client(clnt);
 205        if (IS_ERR(clone))
 206                return clone;
 207
 208        auth = rpcauth_create(flavor, clone);
 209        if (!auth) {
 210                rpc_shutdown_client(clone);
 211                clone = ERR_PTR(-EIO);
 212        }
 213
 214        return clone;
 215}
 216
 217static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 218                                     char *page, char *page2,
 219                                     const struct nfs4_fs_location *location)
 220{
 221        const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 222        struct vfsmount *mnt = ERR_PTR(-ENOENT);
 223        char *mnt_path;
 224        unsigned int maxbuflen;
 225        unsigned int s;
 226
 227        mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 228        if (IS_ERR(mnt_path))
 229                return ERR_CAST(mnt_path);
 230        mountdata->mnt_path = mnt_path;
 231        maxbuflen = mnt_path - 1 - page2;
 232
 233        mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 234        if (mountdata->addr == NULL)
 235                return ERR_PTR(-ENOMEM);
 236
 237        for (s = 0; s < location->nservers; s++) {
 238                const struct nfs4_string *buf = &location->servers[s];
 239
 240                if (buf->len <= 0 || buf->len >= maxbuflen)
 241                        continue;
 242
 243                if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 244                        continue;
 245
 246                mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 247                                mountdata->addr, addr_bufsize,
 248                                NFS_SB(mountdata->sb));
 249                if (mountdata->addrlen == 0)
 250                        continue;
 251
 252                rpc_set_port(mountdata->addr, NFS_PORT);
 253
 254                memcpy(page2, buf->data, buf->len);
 255                page2[buf->len] = '\0';
 256                mountdata->hostname = page2;
 257
 258                snprintf(page, PAGE_SIZE, "%s:%s",
 259                                mountdata->hostname,
 260                                mountdata->mnt_path);
 261
 262                mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 263                if (!IS_ERR(mnt))
 264                        break;
 265        }
 266        kfree(mountdata->addr);
 267        return mnt;
 268}
 269
 270/**
 271 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 272 * @dentry - parent directory
 273 * @locations - array of NFSv4 server location information
 274 *
 275 */
 276static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 277                                            const struct nfs4_fs_locations *locations)
 278{
 279        struct vfsmount *mnt = ERR_PTR(-ENOENT);
 280        struct nfs_clone_mount mountdata = {
 281                .sb = dentry->d_sb,
 282                .dentry = dentry,
 283                .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 284        };
 285        char *page = NULL, *page2 = NULL;
 286        int loc, error;
 287
 288        if (locations == NULL || locations->nlocations <= 0)
 289                goto out;
 290
 291        dprintk("%s: referral at %s/%s\n", __func__,
 292                dentry->d_parent->d_name.name, dentry->d_name.name);
 293
 294        page = (char *) __get_free_page(GFP_USER);
 295        if (!page)
 296                goto out;
 297
 298        page2 = (char *) __get_free_page(GFP_USER);
 299        if (!page2)
 300                goto out;
 301
 302        /* Ensure fs path is a prefix of current dentry path */
 303        error = nfs4_validate_fspath(dentry, locations, page, page2);
 304        if (error < 0) {
 305                mnt = ERR_PTR(error);
 306                goto out;
 307        }
 308
 309        for (loc = 0; loc < locations->nlocations; loc++) {
 310                const struct nfs4_fs_location *location = &locations->locations[loc];
 311
 312                if (location == NULL || location->nservers <= 0 ||
 313                    location->rootpath.ncomponents == 0)
 314                        continue;
 315
 316                mnt = try_location(&mountdata, page, page2, location);
 317                if (!IS_ERR(mnt))
 318                        break;
 319        }
 320
 321out:
 322        free_page((unsigned long) page);
 323        free_page((unsigned long) page2);
 324        dprintk("%s: done\n", __func__);
 325        return mnt;
 326}
 327
 328/*
 329 * nfs_do_refmount - handle crossing a referral on server
 330 * @dentry - dentry of referral
 331 *
 332 */
 333static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 334{
 335        struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 336        struct dentry *parent;
 337        struct nfs4_fs_locations *fs_locations = NULL;
 338        struct page *page;
 339        int err;
 340
 341        /* BUG_ON(IS_ROOT(dentry)); */
 342        dprintk("%s: enter\n", __func__);
 343
 344        page = alloc_page(GFP_KERNEL);
 345        if (page == NULL)
 346                goto out;
 347
 348        fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 349        if (fs_locations == NULL)
 350                goto out_free;
 351
 352        /* Get locations */
 353        mnt = ERR_PTR(-ENOENT);
 354
 355        parent = dget_parent(dentry);
 356        dprintk("%s: getting locations for %s/%s\n",
 357                __func__, parent->d_name.name, dentry->d_name.name);
 358
 359        err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 360        dput(parent);
 361        if (err != 0 ||
 362            fs_locations->nlocations <= 0 ||
 363            fs_locations->fs_path.ncomponents <= 0)
 364                goto out_free;
 365
 366        mnt = nfs_follow_referral(dentry, fs_locations);
 367out_free:
 368        __free_page(page);
 369        kfree(fs_locations);
 370out:
 371        dprintk("%s: done\n", __func__);
 372        return mnt;
 373}
 374
 375struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 376                               struct nfs_fh *fh, struct nfs_fattr *fattr)
 377{
 378        struct dentry *parent = dget_parent(dentry);
 379        struct rpc_clnt *client;
 380        struct vfsmount *mnt;
 381
 382        /* Look it up again to get its attributes and sec flavor */
 383        client = nfs4_proc_lookup_mountpoint(parent->d_inode, &dentry->d_name, fh, fattr);
 384        dput(parent);
 385        if (IS_ERR(client))
 386                return ERR_CAST(client);
 387
 388        if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
 389                mnt = nfs_do_refmount(client, dentry);
 390        else
 391                mnt = nfs_do_submount(dentry, fh, fattr, client->cl_auth->au_flavor);
 392
 393        rpc_shutdown_client(client);
 394        return mnt;
 395}
 396
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