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        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 */
  97static 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
 120static 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
 135rpc_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
 164static 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
 184out:
 185        put_page(page);
 186        return flavor;
 187}
 188
 189/*
 190 * Please call rpc_shutdown_client() when you are done with this client.
 191 */
 192struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
 193                                        struct qstr *name)
 194{
 195        struct rpc_clnt *clone;
 196        struct rpc_auth *auth;
 197        rpc_authflavor_t flavor;
 198
 199        flavor = nfs4_negotiate_security(inode, name);
 200        if ((int)flavor < 0)
 201                return ERR_PTR(flavor);
 202
 203        clone = rpc_clone_client(clnt);
 204        if (IS_ERR(clone))
 205                return clone;
 206
 207        auth = rpcauth_create(flavor, clone);
 208        if (!auth) {
 209                rpc_shutdown_client(clone);
 210                clone = ERR_PTR(-EIO);
 211        }
 212
 213        return clone;
 214}
 215
 216static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
 217                                     char *page, char *page2,
 218                                     const struct nfs4_fs_location *location)
 219{
 220        const size_t addr_bufsize = sizeof(struct sockaddr_storage);
 221        struct vfsmount *mnt = ERR_PTR(-ENOENT);
 222        char *mnt_path;
 223        unsigned int maxbuflen;
 224        unsigned int s;
 225
 226        mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
 227        if (IS_ERR(mnt_path))
 228                return ERR_CAST(mnt_path);
 229        mountdata->mnt_path = mnt_path;
 230        maxbuflen = mnt_path - 1 - page2;
 231
 232        mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
 233        if (mountdata->addr == NULL)
 234                return ERR_PTR(-ENOMEM);
 235
 236        for (s = 0; s < location->nservers; s++) {
 237                const struct nfs4_string *buf = &location->servers[s];
 238
 239                if (buf->len <= 0 || buf->len >= maxbuflen)
 240                        continue;
 241
 242                if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
 243                        continue;
 244
 245                mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
 246                                mountdata->addr, addr_bufsize,
 247                                NFS_SB(mountdata->sb));
 248                if (mountdata->addrlen == 0)
 249                        continue;
 250
 251                rpc_set_port(mountdata->addr, NFS_PORT);
 252
 253                memcpy(page2, buf->data, buf->len);
 254                page2[buf->len] = '\0';
 255                mountdata->hostname = page2;
 256
 257                snprintf(page, PAGE_SIZE, "%s:%s",
 258                                mountdata->hostname,
 259                                mountdata->mnt_path);
 260
 261                mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
 262                if (!IS_ERR(mnt))
 263                        break;
 264        }
 265        kfree(mountdata->addr);
 266        return mnt;
 267}
 268
 269/**
 270 * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
 271 * @dentry - parent directory
 272 * @locations - array of NFSv4 server location information
 273 *
 274 */
 275static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
 276                                            const struct nfs4_fs_locations *locations)
 277{
 278        struct vfsmount *mnt = ERR_PTR(-ENOENT);
 279        struct nfs_clone_mount mountdata = {
 280                .sb = dentry->d_sb,
 281                .dentry = dentry,
 282                .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
 283        };
 284        char *page = NULL, *page2 = NULL;
 285        int loc, error;
 286
 287        if (locations == NULL || locations->nlocations <= 0)
 288                goto out;
 289
 290        dprintk("%s: referral at %s/%s\n", __func__,
 291                dentry->d_parent->d_name.name, dentry->d_name.name);
 292
 293        page = (char *) __get_free_page(GFP_USER);
 294        if (!page)
 295                goto out;
 296
 297        page2 = (char *) __get_free_page(GFP_USER);
 298        if (!page2)
 299                goto out;
 300
 301        /* Ensure fs path is a prefix of current dentry path */
 302        error = nfs4_validate_fspath(dentry, locations, page, page2);
 303        if (error < 0) {
 304                mnt = ERR_PTR(error);
 305                goto out;
 306        }
 307
 308        for (loc = 0; loc < locations->nlocations; loc++) {
 309                const struct nfs4_fs_location *location = &locations->locations[loc];
 310
 311                if (location == NULL || location->nservers <= 0 ||
 312                    location->rootpath.ncomponents == 0)
 313                        continue;
 314
 315                mnt = try_location(&mountdata, page, page2, location);
 316                if (!IS_ERR(mnt))
 317                        break;
 318        }
 319
 320out:
 321        free_page((unsigned long) page);
 322        free_page((unsigned long) page2);
 323        dprintk("%s: done\n", __func__);
 324        return mnt;
 325}
 326
 327/*
 328 * nfs_do_refmount - handle crossing a referral on server
 329 * @dentry - dentry of referral
 330 *
 331 */
 332static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
 333{
 334        struct vfsmount *mnt = ERR_PTR(-ENOMEM);
 335        struct dentry *parent;
 336        struct nfs4_fs_locations *fs_locations = NULL;
 337        struct page *page;
 338        int err;
 339
 340        /* BUG_ON(IS_ROOT(dentry)); */
 341        dprintk("%s: enter\n", __func__);
 342
 343        page = alloc_page(GFP_KERNEL);
 344        if (page == NULL)
 345                goto out;
 346
 347        fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
 348        if (fs_locations == NULL)
 349                goto out_free;
 350
 351        /* Get locations */
 352        mnt = ERR_PTR(-ENOENT);
 353
 354        parent = dget_parent(dentry);
 355        dprintk("%s: getting locations for %s/%s\n",
 356                __func__, parent->d_name.name, dentry->d_name.name);
 357
 358        err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
 359        dput(parent);
 360        if (err != 0 ||
 361            fs_locations->nlocations <= 0 ||
 362            fs_locations->fs_path.ncomponents <= 0)
 363                goto out_free;
 364
 365        mnt = nfs_follow_referral(dentry, fs_locations);
 366out_free:
 367        __free_page(page);
 368        kfree(fs_locations);
 369out:
 370        dprintk("%s: done\n", __func__);
 371        return mnt;
 372}
 373
 374struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
 375                               struct nfs_fh *fh, struct nfs_fattr *fattr)
 376{
 377        struct dentry *parent = dget_parent(dentry);
 378        struct rpc_clnt *client;
 379        struct vfsmount *mnt;
 380
 381        /* Look it up again to get its attributes and sec flavor */
 382        client = nfs4_proc_lookup_mountpoint(parent->d_inode, &dentry->d_name, fh, fattr);
 383        dput(parent);
 384        if (IS_ERR(client))
 385                return ERR_CAST(client);
 386
 387        if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
 388                mnt = nfs_do_refmount(client, dentry);
 389        else
 390                mnt = nfs_do_submount(dentry, fh, fattr, client->cl_auth->au_flavor);
 391
 392        rpc_shutdown_client(client);
 393        return mnt;
 394}
 395
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