xref: /openbmc/linux/fs/nfs/nfs4namespace.c (revision cd5d5810)
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 nfs_server *server)
125 {
126 	struct net *net = rpc_net_ns(server->client);
127 	ssize_t ret;
128 
129 	ret = rpc_pton(net, string, len, sa, salen);
130 	if (ret == 0) {
131 		ret = nfs_dns_resolve_name(net, string, len, sa, salen);
132 		if (ret < 0)
133 			ret = 0;
134 	}
135 	return ret;
136 }
137 
138 /**
139  * nfs_find_best_sec - Find a security mechanism supported locally
140  * @flavors: List of security tuples returned by SECINFO procedure
141  *
142  * Return the pseudoflavor of the first security mechanism in
143  * "flavors" that is locally supported.  Return RPC_AUTH_UNIX if
144  * no matching flavor is found in the array.  The "flavors" array
145  * is searched in the order returned from the server, per RFC 3530
146  * recommendation.
147  */
148 rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
149 {
150 	rpc_authflavor_t pseudoflavor;
151 	struct nfs4_secinfo4 *secinfo;
152 	unsigned int i;
153 
154 	for (i = 0; i < flavors->num_flavors; i++) {
155 		secinfo = &flavors->flavors[i];
156 
157 		switch (secinfo->flavor) {
158 		case RPC_AUTH_NULL:
159 		case RPC_AUTH_UNIX:
160 		case RPC_AUTH_GSS:
161 			pseudoflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
162 							&secinfo->flavor_info);
163 			if (pseudoflavor != RPC_AUTH_MAXFLAVOR)
164 				return pseudoflavor;
165 			break;
166 		}
167 	}
168 
169 	return RPC_AUTH_UNIX;
170 }
171 
172 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
173 {
174 	struct page *page;
175 	struct nfs4_secinfo_flavors *flavors;
176 	rpc_authflavor_t flavor;
177 	int err;
178 
179 	page = alloc_page(GFP_KERNEL);
180 	if (!page)
181 		return -ENOMEM;
182 	flavors = page_address(page);
183 
184 	err = nfs4_proc_secinfo(inode, name, flavors);
185 	if (err < 0) {
186 		flavor = err;
187 		goto out;
188 	}
189 
190 	flavor = nfs_find_best_sec(flavors);
191 
192 out:
193 	put_page(page);
194 	return flavor;
195 }
196 
197 /*
198  * Please call rpc_shutdown_client() when you are done with this client.
199  */
200 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
201 					struct qstr *name)
202 {
203 	rpc_authflavor_t flavor;
204 
205 	flavor = nfs4_negotiate_security(inode, name);
206 	if ((int)flavor < 0)
207 		return ERR_PTR((int)flavor);
208 
209 	return rpc_clone_client_set_auth(clnt, flavor);
210 }
211 
212 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
213 				     char *page, char *page2,
214 				     const struct nfs4_fs_location *location)
215 {
216 	const size_t addr_bufsize = sizeof(struct sockaddr_storage);
217 	struct vfsmount *mnt = ERR_PTR(-ENOENT);
218 	char *mnt_path;
219 	unsigned int maxbuflen;
220 	unsigned int s;
221 
222 	mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
223 	if (IS_ERR(mnt_path))
224 		return ERR_CAST(mnt_path);
225 	mountdata->mnt_path = mnt_path;
226 	maxbuflen = mnt_path - 1 - page2;
227 
228 	mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
229 	if (mountdata->addr == NULL)
230 		return ERR_PTR(-ENOMEM);
231 
232 	for (s = 0; s < location->nservers; s++) {
233 		const struct nfs4_string *buf = &location->servers[s];
234 
235 		if (buf->len <= 0 || buf->len >= maxbuflen)
236 			continue;
237 
238 		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
239 			continue;
240 
241 		mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
242 				mountdata->addr, addr_bufsize,
243 				NFS_SB(mountdata->sb));
244 		if (mountdata->addrlen == 0)
245 			continue;
246 
247 		rpc_set_port(mountdata->addr, NFS_PORT);
248 
249 		memcpy(page2, buf->data, buf->len);
250 		page2[buf->len] = '\0';
251 		mountdata->hostname = page2;
252 
253 		snprintf(page, PAGE_SIZE, "%s:%s",
254 				mountdata->hostname,
255 				mountdata->mnt_path);
256 
257 		mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
258 		if (!IS_ERR(mnt))
259 			break;
260 	}
261 	kfree(mountdata->addr);
262 	return mnt;
263 }
264 
265 /**
266  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
267  * @dentry - parent directory
268  * @locations - array of NFSv4 server location information
269  *
270  */
271 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
272 					    const struct nfs4_fs_locations *locations)
273 {
274 	struct vfsmount *mnt = ERR_PTR(-ENOENT);
275 	struct nfs_clone_mount mountdata = {
276 		.sb = dentry->d_sb,
277 		.dentry = dentry,
278 		.authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
279 	};
280 	char *page = NULL, *page2 = NULL;
281 	int loc, error;
282 
283 	if (locations == NULL || locations->nlocations <= 0)
284 		goto out;
285 
286 	dprintk("%s: referral at %s/%s\n", __func__,
287 		dentry->d_parent->d_name.name, dentry->d_name.name);
288 
289 	page = (char *) __get_free_page(GFP_USER);
290 	if (!page)
291 		goto out;
292 
293 	page2 = (char *) __get_free_page(GFP_USER);
294 	if (!page2)
295 		goto out;
296 
297 	/* Ensure fs path is a prefix of current dentry path */
298 	error = nfs4_validate_fspath(dentry, locations, page, page2);
299 	if (error < 0) {
300 		mnt = ERR_PTR(error);
301 		goto out;
302 	}
303 
304 	for (loc = 0; loc < locations->nlocations; loc++) {
305 		const struct nfs4_fs_location *location = &locations->locations[loc];
306 
307 		if (location == NULL || location->nservers <= 0 ||
308 		    location->rootpath.ncomponents == 0)
309 			continue;
310 
311 		mnt = try_location(&mountdata, page, page2, location);
312 		if (!IS_ERR(mnt))
313 			break;
314 	}
315 
316 out:
317 	free_page((unsigned long) page);
318 	free_page((unsigned long) page2);
319 	dprintk("%s: done\n", __func__);
320 	return mnt;
321 }
322 
323 /*
324  * nfs_do_refmount - handle crossing a referral on server
325  * @dentry - dentry of referral
326  *
327  */
328 static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
329 {
330 	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
331 	struct dentry *parent;
332 	struct nfs4_fs_locations *fs_locations = NULL;
333 	struct page *page;
334 	int err;
335 
336 	/* BUG_ON(IS_ROOT(dentry)); */
337 	dprintk("%s: enter\n", __func__);
338 
339 	page = alloc_page(GFP_KERNEL);
340 	if (page == NULL)
341 		goto out;
342 
343 	fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
344 	if (fs_locations == NULL)
345 		goto out_free;
346 
347 	/* Get locations */
348 	mnt = ERR_PTR(-ENOENT);
349 
350 	parent = dget_parent(dentry);
351 	dprintk("%s: getting locations for %s/%s\n",
352 		__func__, parent->d_name.name, dentry->d_name.name);
353 
354 	err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
355 	dput(parent);
356 	if (err != 0 ||
357 	    fs_locations->nlocations <= 0 ||
358 	    fs_locations->fs_path.ncomponents <= 0)
359 		goto out_free;
360 
361 	mnt = nfs_follow_referral(dentry, fs_locations);
362 out_free:
363 	__free_page(page);
364 	kfree(fs_locations);
365 out:
366 	dprintk("%s: done\n", __func__);
367 	return mnt;
368 }
369 
370 struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
371 			       struct nfs_fh *fh, struct nfs_fattr *fattr)
372 {
373 	rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
374 	struct dentry *parent = dget_parent(dentry);
375 	struct inode *dir = parent->d_inode;
376 	struct qstr *name = &dentry->d_name;
377 	struct rpc_clnt *client;
378 	struct vfsmount *mnt;
379 
380 	/* Look it up again to get its attributes and sec flavor */
381 	client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
382 	dput(parent);
383 	if (IS_ERR(client))
384 		return ERR_CAST(client);
385 
386 	if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
387 		mnt = nfs_do_refmount(client, dentry);
388 		goto out;
389 	}
390 
391 	if (client->cl_auth->au_flavor != flavor)
392 		flavor = client->cl_auth->au_flavor;
393 	else if (!(server->flags & NFS_MOUNT_SECFLAVOUR)) {
394 		rpc_authflavor_t new = nfs4_negotiate_security(dir, name);
395 		if ((int)new >= 0)
396 			flavor = new;
397 	}
398 	mnt = nfs_do_submount(dentry, fh, fattr, flavor);
399 out:
400 	rpc_shutdown_client(client);
401 	return mnt;
402 }
403