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 */
32static 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;
52Elong:
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 */
62static 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 */
83static 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 */
100static 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
123static 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 */
153static 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 */
209struct rpc_clnt *
210nfs4_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
232out:
233	put_page(page);
234	return new;
235}
236
237static 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 */
296static 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
340out:
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 */
352static 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);
386out_free:
387	__free_page(page);
388	kfree(fs_locations);
389out:
390	dprintk("%s: done\n", __func__);
391	return mnt;
392}
393
394struct 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);
418out:
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 */
428static 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 */
487int 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
519out:
520	free_page((unsigned long)page);
521	free_page((unsigned long)page2);
522	return error;
523}
524