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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/nfs_mount.h>
 15 #include <linux/slab.h>
 16 #include <linux/string.h>
 17 #include <linux/sunrpc/clnt.h>
 18 #include <linux/sunrpc/addr.h>
 19 #include <linux/vfs.h>
 20 #include <linux/inet.h>
 21 #include "internal.h"
 22 #include "nfs4_fs.h"
 23 #include "dns_resolve.h"
 24 
 25 #define NFSDBG_FACILITY         NFSDBG_VFS
 26 
 27 /*
 28  * Convert the NFSv4 pathname components into a standard posix path.
 29  *
 30  * Note that the resulting string will be placed at the end of the buffer
 31  */
 32 static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
 33                                          char *buffer, ssize_t buflen)
 34 {
 35         char *end = buffer + buflen;
 36         int n;
 37 
 38         *--end = '\0';
 39         buflen--;
 40 
 41         n = pathname->ncomponents;
 42         while (--n >= 0) {
 43                 const struct nfs4_string *component = &pathname->components[n];
 44                 buflen -= component->len + 1;
 45                 if (buflen < 0)
 46                         goto Elong;
 47                 end -= component->len;
 48                 memcpy(end, component->data, component->len);
 49                 *--end = '/';
 50         }
 51         return end;
 52 Elong:
 53         return ERR_PTR(-ENAMETOOLONG);
 54 }
 55 
 56 /*
 57  * return the path component of "<server>:<path>"
 58  *  nfspath - the "<server>:<path>" string
 59  *  end - one past the last char that could contain "<server>:"
 60  * returns NULL on failure
 61  */
 62 static char *nfs_path_component(const char *nfspath, const char *end)
 63 {
 64         char *p;
 65 
 66         if (*nfspath == '[') {
 67                 /* parse [] escaped IPv6 addrs */
 68                 p = strchr(nfspath, ']');
 69                 if (p != NULL && ++p < end && *p == ':')
 70                         return p + 1;
 71         } else {
 72                 /* otherwise split on first colon */
 73                 p = strchr(nfspath, ':');
 74                 if (p != NULL && p < end)
 75                         return p + 1;
 76         }
 77         return NULL;
 78 }
 79 
 80 /*
 81  * Determine the mount path as a string
 82  */
 83 static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
 84 {
 85         char *limit;
 86         char *path = nfs_path(&limit, dentry, buffer, buflen,
 87                               NFS_PATH_CANONICAL);
 88         if (!IS_ERR(path)) {
 89                 char *path_component = nfs_path_component(path, limit);
 90                 if (path_component)
 91                         return path_component;
 92         }
 93         return path;
 94 }
 95 
 96 /*
 97  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
 98  * believe to be the server path to this dentry
 99  */
100 static int nfs4_validate_fspath(struct dentry *dentry,
101                                 const struct nfs4_fs_locations *locations,
102                                 char *page, char *page2)
103 {
104         const char *path, *fs_path;
105 
106         path = nfs4_path(dentry, page, PAGE_SIZE);
107         if (IS_ERR(path))
108                 return PTR_ERR(path);
109 
110         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
111         if (IS_ERR(fs_path))
112                 return PTR_ERR(fs_path);
113 
114         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
115                 dprintk("%s: path %s does not begin with fsroot %s\n",
116                         __func__, path, fs_path);
117                 return -ENOENT;
118         }
119 
120         return 0;
121 }
122 
123 static size_t nfs_parse_server_name(char *string, size_t len,
124                 struct sockaddr *sa, size_t salen, struct net *net)
125 {
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  * @server: NFS server struct
140  * @flavors: List of security tuples returned by SECINFO procedure
141  *
142  * Return an rpc client that uses the first security mechanism in
143  * "flavors" that is locally supported.  The "flavors" array
144  * is searched in the order returned from the server, per RFC 3530
145  * recommendation and each flavor is checked for membership in the
146  * sec= mount option list if it exists.
147  *
148  * Return -EPERM if no matching flavor is found in the array.
149  *
150  * Please call rpc_shutdown_client() when you are done with this rpc client.
151  *
152  */
153 static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
154                                           struct nfs_server *server,
155                                           struct nfs4_secinfo_flavors *flavors)
156 {
157         rpc_authflavor_t pflavor;
158         struct nfs4_secinfo4 *secinfo;
159         unsigned int i;
160 
161         for (i = 0; i < flavors->num_flavors; i++) {
162                 secinfo = &flavors->flavors[i];
163 
164                 switch (secinfo->flavor) {
165                 case RPC_AUTH_NULL:
166                 case RPC_AUTH_UNIX:
167                 case RPC_AUTH_GSS:
168                         pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
169                                                         &secinfo->flavor_info);
170                         /* does the pseudoflavor match a sec= mount opt? */
171                         if (pflavor != RPC_AUTH_MAXFLAVOR &&
172                             nfs_auth_info_match(&server->auth_info, pflavor)) {
173                                 struct rpc_clnt *new;
174                                 struct rpc_cred *cred;
175 
176                                 /* Cloning creates an rpc_auth for the flavor */
177                                 new = rpc_clone_client_set_auth(clnt, pflavor);
178                                 if (IS_ERR(new))
179                                         continue;
180                                 /**
181                                 * Check that the user actually can use the
182                                 * flavor. This is mostly for RPC_AUTH_GSS
183                                 * where cr_init obtains a gss context
184                                 */
185                                 cred = rpcauth_lookupcred(new->cl_auth, 0);
186                                 if (IS_ERR(cred)) {
187                                         rpc_shutdown_client(new);
188                                         continue;
189                                 }
190                                 put_rpccred(cred);
191                                 return new;
192                         }
193                 }
194         }
195         return ERR_PTR(-EPERM);
196 }
197 
198 /**
199  * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
200  * return an rpc_clnt that uses the best available security flavor with
201  * respect to the secinfo flavor list and the sec= mount options.
202  *
203  * @clnt: RPC client to clone
204  * @inode: directory inode
205  * @name: lookup name
206  *
207  * Please call rpc_shutdown_client() when you are done with this rpc client.
208  */
209 struct rpc_clnt *
210 nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
211                                         struct qstr *name)
212 {
213         struct page *page;
214         struct nfs4_secinfo_flavors *flavors;
215         struct rpc_clnt *new;
216         int err;
217 
218         page = alloc_page(GFP_KERNEL);
219         if (!page)
220                 return ERR_PTR(-ENOMEM);
221 
222         flavors = page_address(page);
223 
224         err = nfs4_proc_secinfo(inode, name, flavors);
225         if (err < 0) {
226                 new = ERR_PTR(err);
227                 goto out;
228         }
229 
230         new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
231 
232 out:
233         put_page(page);
234         return new;
235 }
236 
237 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
238                                      char *page, char *page2,
239                                      const struct nfs4_fs_location *location)
240 {
241         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
242         struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client);
243         struct vfsmount *mnt = ERR_PTR(-ENOENT);
244         char *mnt_path;
245         unsigned int maxbuflen;
246         unsigned int s;
247 
248         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
249         if (IS_ERR(mnt_path))
250                 return ERR_CAST(mnt_path);
251         mountdata->mnt_path = mnt_path;
252         maxbuflen = mnt_path - 1 - page2;
253 
254         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
255         if (mountdata->addr == NULL)
256                 return ERR_PTR(-ENOMEM);
257 
258         for (s = 0; s < location->nservers; s++) {
259                 const struct nfs4_string *buf = &location->servers[s];
260 
261                 if (buf->len <= 0 || buf->len >= maxbuflen)
262                         continue;
263 
264                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
265                         continue;
266 
267                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
268                                 mountdata->addr, addr_bufsize, net);
269                 if (mountdata->addrlen == 0)
270                         continue;
271 
272                 rpc_set_port(mountdata->addr, NFS_PORT);
273 
274                 memcpy(page2, buf->data, buf->len);
275                 page2[buf->len] = '\0';
276                 mountdata->hostname = page2;
277 
278                 snprintf(page, PAGE_SIZE, "%s:%s",
279                                 mountdata->hostname,
280                                 mountdata->mnt_path);
281 
282                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
283                 if (!IS_ERR(mnt))
284                         break;
285         }
286         kfree(mountdata->addr);
287         return mnt;
288 }
289 
290 /**
291  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
292  * @dentry - parent directory
293  * @locations - array of NFSv4 server location information
294  *
295  */
296 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
297                                             const struct nfs4_fs_locations *locations)
298 {
299         struct vfsmount *mnt = ERR_PTR(-ENOENT);
300         struct nfs_clone_mount mountdata = {
301                 .sb = dentry->d_sb,
302                 .dentry = dentry,
303                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
304         };
305         char *page = NULL, *page2 = NULL;
306         int loc, error;
307 
308         if (locations == NULL || locations->nlocations <= 0)
309                 goto out;
310 
311         dprintk("%s: referral at %pd2\n", __func__, dentry);
312 
313         page = (char *) __get_free_page(GFP_USER);
314         if (!page)
315                 goto out;
316 
317         page2 = (char *) __get_free_page(GFP_USER);
318         if (!page2)
319                 goto out;
320 
321         /* Ensure fs path is a prefix of current dentry path */
322         error = nfs4_validate_fspath(dentry, locations, page, page2);
323         if (error < 0) {
324                 mnt = ERR_PTR(error);
325                 goto out;
326         }
327 
328         for (loc = 0; loc < locations->nlocations; loc++) {
329                 const struct nfs4_fs_location *location = &locations->locations[loc];
330 
331                 if (location == NULL || location->nservers <= 0 ||
332                     location->rootpath.ncomponents == 0)
333                         continue;
334 
335                 mnt = try_location(&mountdata, page, page2, location);
336                 if (!IS_ERR(mnt))
337                         break;
338         }
339 
340 out:
341         free_page((unsigned long) page);
342         free_page((unsigned long) page2);
343         dprintk("%s: done\n", __func__);
344         return mnt;
345 }
346 
347 /*
348  * nfs_do_refmount - handle crossing a referral on server
349  * @dentry - dentry of referral
350  *
351  */
352 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
353 {
354         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
355         struct dentry *parent;
356         struct nfs4_fs_locations *fs_locations = NULL;
357         struct page *page;
358         int err;
359 
360         /* BUG_ON(IS_ROOT(dentry)); */
361         dprintk("%s: enter\n", __func__);
362 
363         page = alloc_page(GFP_KERNEL);
364         if (page == NULL)
365                 goto out;
366 
367         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
368         if (fs_locations == NULL)
369                 goto out_free;
370 
371         /* Get locations */
372         mnt = ERR_PTR(-ENOENT);
373 
374         parent = dget_parent(dentry);
375         dprintk("%s: getting locations for %pd2\n",
376                 __func__, dentry);
377 
378         err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);
379         dput(parent);
380         if (err != 0 ||
381             fs_locations->nlocations <= 0 ||
382             fs_locations->fs_path.ncomponents <= 0)
383                 goto out_free;
384 
385         mnt = nfs_follow_referral(dentry, fs_locations);
386 out_free:
387         __free_page(page);
388         kfree(fs_locations);
389 out:
390         dprintk("%s: done\n", __func__);
391         return mnt;
392 }
393 
394 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
395                                struct nfs_fh *fh, struct nfs_fattr *fattr)
396 {
397         rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
398         struct dentry *parent = dget_parent(dentry);
399         struct inode *dir = d_inode(parent);
400         struct qstr *name = &dentry->d_name;
401         struct rpc_clnt *client;
402         struct vfsmount *mnt;
403 
404         /* Look it up again to get its attributes and sec flavor */
405         client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
406         dput(parent);
407         if (IS_ERR(client))
408                 return ERR_CAST(client);
409 
410         if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
411                 mnt = nfs_do_refmount(client, dentry);
412                 goto out;
413         }
414 
415         if (client->cl_auth->au_flavor != flavor)
416                 flavor = client->cl_auth->au_flavor;
417         mnt = nfs_do_submount(dentry, fh, fattr, flavor);
418 out:
419         rpc_shutdown_client(client);
420         return mnt;
421 }
422 
423 /*
424  * Try one location from the fs_locations array.
425  *
426  * Returns zero on success, or a negative errno value.
427  */
428 static int nfs4_try_replacing_one_location(struct nfs_server *server,
429                 char *page, char *page2,
430                 const struct nfs4_fs_location *location)
431 {
432         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
433         struct net *net = rpc_net_ns(server->client);
434         struct sockaddr *sap;
435         unsigned int s;
436         size_t salen;
437         int error;
438 
439         sap = kmalloc(addr_bufsize, GFP_KERNEL);
440         if (sap == NULL)
441                 return -ENOMEM;
442 
443         error = -ENOENT;
444         for (s = 0; s < location->nservers; s++) {
445                 const struct nfs4_string *buf = &location->servers[s];
446                 char *hostname;
447 
448                 if (buf->len <= 0 || buf->len > PAGE_SIZE)
449                         continue;
450 
451                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
452                         continue;
453 
454                 salen = nfs_parse_server_name(buf->data, buf->len,
455                                                 sap, addr_bufsize, net);
456                 if (salen == 0)
457                         continue;
458                 rpc_set_port(sap, NFS_PORT);
459 
460                 error = -ENOMEM;
461                 hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
462                 if (hostname == NULL)
463                         break;
464 
465                 error = nfs4_update_server(server, hostname, sap, salen, net);
466                 kfree(hostname);
467                 if (error == 0)
468                         break;
469         }
470 
471         kfree(sap);
472         return error;
473 }
474 
475 /**
476  * nfs4_replace_transport - set up transport to destination server
477  *
478  * @server: export being migrated
479  * @locations: fs_locations array
480  *
481  * Returns zero on success, or a negative errno value.
482  *
483  * The client tries all the entries in the "locations" array, in the
484  * order returned by the server, until one works or the end of the
485  * array is reached.
486  */
487 int nfs4_replace_transport(struct nfs_server *server,
488                            const struct nfs4_fs_locations *locations)
489 {
490         char *page = NULL, *page2 = NULL;
491         int loc, error;
492 
493         error = -ENOENT;
494         if (locations == NULL || locations->nlocations <= 0)
495                 goto out;
496 
497         error = -ENOMEM;
498         page = (char *) __get_free_page(GFP_USER);
499         if (!page)
500                 goto out;
501         page2 = (char *) __get_free_page(GFP_USER);
502         if (!page2)
503                 goto out;
504 
505         for (loc = 0; loc < locations->nlocations; loc++) {
506                 const struct nfs4_fs_location *location =
507                                                 &locations->locations[loc];
508 
509                 if (location == NULL || location->nservers <= 0 ||
510                     location->rootpath.ncomponents == 0)
511                         continue;
512 
513                 error = nfs4_try_replacing_one_location(server, page,
514                                                         page2, location);
515                 if (error == 0)
516                         break;
517         }
518 
519 out:
520         free_page((unsigned long)page);
521         free_page((unsigned long)page2);
522         return error;
523 }
524 

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