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}