xref: /openbmc/linux/fs/nfs/nfs4namespace.c (revision 63dc02bd) 
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  */
30 static 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;
50 Elong:
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  */
60 static 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  */
81 static 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  */
97 static 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 
120 static 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 
135 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
136 {
137 	struct page *page;
138 	struct nfs4_secinfo_flavors *flavors;
139 	rpc_authflavor_t flavor;
140 	int err;
141 
142 	page = alloc_page(GFP_KERNEL);
143 	if (!page)
144 		return -ENOMEM;
145 	flavors = page_address(page);
146 
147 	err = nfs4_proc_secinfo(inode, name, flavors);
148 	if (err < 0) {
149 		flavor = err;
150 		goto out;
151 	}
152 
153 	flavor = nfs_find_best_sec(flavors);
154 
155 out:
156 	put_page(page);
157 	return flavor;
158 }
159 
160 /*
161  * Please call rpc_shutdown_client() when you are done with this client.
162  */
163 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
164 					struct qstr *name)
165 {
166 	struct rpc_clnt *clone;
167 	struct rpc_auth *auth;
168 	rpc_authflavor_t flavor;
169 
170 	flavor = nfs4_negotiate_security(inode, name);
171 	if (flavor < 0)
172 		return ERR_PTR(flavor);
173 
174 	clone = rpc_clone_client(clnt);
175 	if (IS_ERR(clone))
176 		return clone;
177 
178 	auth = rpcauth_create(flavor, clone);
179 	if (!auth) {
180 		rpc_shutdown_client(clone);
181 		clone = ERR_PTR(-EIO);
182 	}
183 
184 	return clone;
185 }
186 
187 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
188 				     char *page, char *page2,
189 				     const struct nfs4_fs_location *location)
190 {
191 	const size_t addr_bufsize = sizeof(struct sockaddr_storage);
192 	struct vfsmount *mnt = ERR_PTR(-ENOENT);
193 	char *mnt_path;
194 	unsigned int maxbuflen;
195 	unsigned int s;
196 
197 	mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
198 	if (IS_ERR(mnt_path))
199 		return ERR_CAST(mnt_path);
200 	mountdata->mnt_path = mnt_path;
201 	maxbuflen = mnt_path - 1 - page2;
202 
203 	mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
204 	if (mountdata->addr == NULL)
205 		return ERR_PTR(-ENOMEM);
206 
207 	for (s = 0; s < location->nservers; s++) {
208 		const struct nfs4_string *buf = &location->servers[s];
209 
210 		if (buf->len <= 0 || buf->len >= maxbuflen)
211 			continue;
212 
213 		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
214 			continue;
215 
216 		mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
217 				mountdata->addr, addr_bufsize,
218 				NFS_SB(mountdata->sb));
219 		if (mountdata->addrlen == 0)
220 			continue;
221 
222 		rpc_set_port(mountdata->addr, NFS_PORT);
223 
224 		memcpy(page2, buf->data, buf->len);
225 		page2[buf->len] = '\0';
226 		mountdata->hostname = page2;
227 
228 		snprintf(page, PAGE_SIZE, "%s:%s",
229 				mountdata->hostname,
230 				mountdata->mnt_path);
231 
232 		mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
233 		if (!IS_ERR(mnt))
234 			break;
235 	}
236 	kfree(mountdata->addr);
237 	return mnt;
238 }
239 
240 /**
241  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
242  * @dentry - parent directory
243  * @locations - array of NFSv4 server location information
244  *
245  */
246 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
247 					    const struct nfs4_fs_locations *locations)
248 {
249 	struct vfsmount *mnt = ERR_PTR(-ENOENT);
250 	struct nfs_clone_mount mountdata = {
251 		.sb = dentry->d_sb,
252 		.dentry = dentry,
253 		.authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
254 	};
255 	char *page = NULL, *page2 = NULL;
256 	int loc, error;
257 
258 	if (locations == NULL || locations->nlocations <= 0)
259 		goto out;
260 
261 	dprintk("%s: referral at %s/%s\n", __func__,
262 		dentry->d_parent->d_name.name, dentry->d_name.name);
263 
264 	page = (char *) __get_free_page(GFP_USER);
265 	if (!page)
266 		goto out;
267 
268 	page2 = (char *) __get_free_page(GFP_USER);
269 	if (!page2)
270 		goto out;
271 
272 	/* Ensure fs path is a prefix of current dentry path */
273 	error = nfs4_validate_fspath(dentry, locations, page, page2);
274 	if (error < 0) {
275 		mnt = ERR_PTR(error);
276 		goto out;
277 	}
278 
279 	for (loc = 0; loc < locations->nlocations; loc++) {
280 		const struct nfs4_fs_location *location = &locations->locations[loc];
281 
282 		if (location == NULL || location->nservers <= 0 ||
283 		    location->rootpath.ncomponents == 0)
284 			continue;
285 
286 		mnt = try_location(&mountdata, page, page2, location);
287 		if (!IS_ERR(mnt))
288 			break;
289 	}
290 
291 out:
292 	free_page((unsigned long) page);
293 	free_page((unsigned long) page2);
294 	dprintk("%s: done\n", __func__);
295 	return mnt;
296 }
297 
298 /*
299  * nfs_do_refmount - handle crossing a referral on server
300  * @dentry - dentry of referral
301  *
302  */
303 struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
304 {
305 	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
306 	struct dentry *parent;
307 	struct nfs4_fs_locations *fs_locations = NULL;
308 	struct page *page;
309 	int err;
310 
311 	/* BUG_ON(IS_ROOT(dentry)); */
312 	dprintk("%s: enter\n", __func__);
313 
314 	page = alloc_page(GFP_KERNEL);
315 	if (page == NULL)
316 		goto out;
317 
318 	fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
319 	if (fs_locations == NULL)
320 		goto out_free;
321 
322 	/* Get locations */
323 	mnt = ERR_PTR(-ENOENT);
324 
325 	parent = dget_parent(dentry);
326 	dprintk("%s: getting locations for %s/%s\n",
327 		__func__, parent->d_name.name, dentry->d_name.name);
328 
329 	err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
330 	dput(parent);
331 	if (err != 0 ||
332 	    fs_locations->nlocations <= 0 ||
333 	    fs_locations->fs_path.ncomponents <= 0)
334 		goto out_free;
335 
336 	mnt = nfs_follow_referral(dentry, fs_locations);
337 out_free:
338 	__free_page(page);
339 	kfree(fs_locations);
340 out:
341 	dprintk("%s: done\n", __func__);
342 	return mnt;
343 }
344