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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/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                               NFS_PATH_CANONICAL);
 86         if (!IS_ERR(path)) {
 87                 char *path_component = nfs_path_component(path, limit);
 88                 if (path_component)
 89                         return path_component;
 90         }
 91         return path;
 92 }
 93 
 94 /*
 95  * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
 96  * believe to be the server path to this dentry
 97  */
 98 static int nfs4_validate_fspath(struct dentry *dentry,
 99                                 const struct nfs4_fs_locations *locations,
100                                 char *page, char *page2)
101 {
102         const char *path, *fs_path;
103 
104         path = nfs4_path(dentry, page, PAGE_SIZE);
105         if (IS_ERR(path))
106                 return PTR_ERR(path);
107 
108         fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
109         if (IS_ERR(fs_path))
110                 return PTR_ERR(fs_path);
111 
112         if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
113                 dprintk("%s: path %s does not begin with fsroot %s\n",
114                         __func__, path, fs_path);
115                 return -ENOENT;
116         }
117 
118         return 0;
119 }
120 
121 static size_t nfs_parse_server_name(char *string, size_t len,
122                 struct sockaddr *sa, size_t salen, struct nfs_server *server)
123 {
124         struct net *net = rpc_net_ns(server->client);
125         ssize_t ret;
126 
127         ret = rpc_pton(net, string, len, sa, salen);
128         if (ret == 0) {
129                 ret = nfs_dns_resolve_name(net, string, len, sa, salen);
130                 if (ret < 0)
131                         ret = 0;
132         }
133         return ret;
134 }
135 
136 static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
137 {
138         struct page *page;
139         struct nfs4_secinfo_flavors *flavors;
140         rpc_authflavor_t flavor;
141         int err;
142 
143         page = alloc_page(GFP_KERNEL);
144         if (!page)
145                 return -ENOMEM;
146         flavors = page_address(page);
147 
148         err = nfs4_proc_secinfo(inode, name, flavors);
149         if (err < 0) {
150                 flavor = err;
151                 goto out;
152         }
153 
154         flavor = nfs_find_best_sec(flavors);
155 
156 out:
157         put_page(page);
158         return flavor;
159 }
160 
161 /*
162  * Please call rpc_shutdown_client() when you are done with this client.
163  */
164 struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
165                                         struct qstr *name)
166 {
167         struct rpc_clnt *clone;
168         struct rpc_auth *auth;
169         rpc_authflavor_t flavor;
170 
171         flavor = nfs4_negotiate_security(inode, name);
172         if (flavor < 0)
173                 return ERR_PTR(flavor);
174 
175         clone = rpc_clone_client(clnt);
176         if (IS_ERR(clone))
177                 return clone;
178 
179         auth = rpcauth_create(flavor, clone);
180         if (!auth) {
181                 rpc_shutdown_client(clone);
182                 clone = ERR_PTR(-EIO);
183         }
184 
185         return clone;
186 }
187 
188 static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
189                                      char *page, char *page2,
190                                      const struct nfs4_fs_location *location)
191 {
192         const size_t addr_bufsize = sizeof(struct sockaddr_storage);
193         struct vfsmount *mnt = ERR_PTR(-ENOENT);
194         char *mnt_path;
195         unsigned int maxbuflen;
196         unsigned int s;
197 
198         mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
199         if (IS_ERR(mnt_path))
200                 return ERR_CAST(mnt_path);
201         mountdata->mnt_path = mnt_path;
202         maxbuflen = mnt_path - 1 - page2;
203 
204         mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
205         if (mountdata->addr == NULL)
206                 return ERR_PTR(-ENOMEM);
207 
208         for (s = 0; s < location->nservers; s++) {
209                 const struct nfs4_string *buf = &location->servers[s];
210 
211                 if (buf->len <= 0 || buf->len >= maxbuflen)
212                         continue;
213 
214                 if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
215                         continue;
216 
217                 mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
218                                 mountdata->addr, addr_bufsize,
219                                 NFS_SB(mountdata->sb));
220                 if (mountdata->addrlen == 0)
221                         continue;
222 
223                 rpc_set_port(mountdata->addr, NFS_PORT);
224 
225                 memcpy(page2, buf->data, buf->len);
226                 page2[buf->len] = '\0';
227                 mountdata->hostname = page2;
228 
229                 snprintf(page, PAGE_SIZE, "%s:%s",
230                                 mountdata->hostname,
231                                 mountdata->mnt_path);
232 
233                 mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
234                 if (!IS_ERR(mnt))
235                         break;
236         }
237         kfree(mountdata->addr);
238         return mnt;
239 }
240 
241 /**
242  * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
243  * @dentry - parent directory
244  * @locations - array of NFSv4 server location information
245  *
246  */
247 static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
248                                             const struct nfs4_fs_locations *locations)
249 {
250         struct vfsmount *mnt = ERR_PTR(-ENOENT);
251         struct nfs_clone_mount mountdata = {
252                 .sb = dentry->d_sb,
253                 .dentry = dentry,
254                 .authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
255         };
256         char *page = NULL, *page2 = NULL;
257         int loc, error;
258 
259         if (locations == NULL || locations->nlocations <= 0)
260                 goto out;
261 
262         dprintk("%s: referral at %s/%s\n", __func__,
263                 dentry->d_parent->d_name.name, dentry->d_name.name);
264 
265         page = (char *) __get_free_page(GFP_USER);
266         if (!page)
267                 goto out;
268 
269         page2 = (char *) __get_free_page(GFP_USER);
270         if (!page2)
271                 goto out;
272 
273         /* Ensure fs path is a prefix of current dentry path */
274         error = nfs4_validate_fspath(dentry, locations, page, page2);
275         if (error < 0) {
276                 mnt = ERR_PTR(error);
277                 goto out;
278         }
279 
280         for (loc = 0; loc < locations->nlocations; loc++) {
281                 const struct nfs4_fs_location *location = &locations->locations[loc];
282 
283                 if (location == NULL || location->nservers <= 0 ||
284                     location->rootpath.ncomponents == 0)
285                         continue;
286 
287                 mnt = try_location(&mountdata, page, page2, location);
288                 if (!IS_ERR(mnt))
289                         break;
290         }
291 
292 out:
293         free_page((unsigned long) page);
294         free_page((unsigned long) page2);
295         dprintk("%s: done\n", __func__);
296         return mnt;
297 }
298 
299 /*
300  * nfs_do_refmount - handle crossing a referral on server
301  * @dentry - dentry of referral
302  *
303  */
304 struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
305 {
306         struct vfsmount *mnt = ERR_PTR(-ENOMEM);
307         struct dentry *parent;
308         struct nfs4_fs_locations *fs_locations = NULL;
309         struct page *page;
310         int err;
311 
312         /* BUG_ON(IS_ROOT(dentry)); */
313         dprintk("%s: enter\n", __func__);
314 
315         page = alloc_page(GFP_KERNEL);
316         if (page == NULL)
317                 goto out;
318 
319         fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
320         if (fs_locations == NULL)
321                 goto out_free;
322 
323         /* Get locations */
324         mnt = ERR_PTR(-ENOENT);
325 
326         parent = dget_parent(dentry);
327         dprintk("%s: getting locations for %s/%s\n",
328                 __func__, parent->d_name.name, dentry->d_name.name);
329 
330         err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
331         dput(parent);
332         if (err != 0 ||
333             fs_locations->nlocations <= 0 ||
334             fs_locations->fs_path.ncomponents <= 0)
335                 goto out_free;
336 
337         mnt = nfs_follow_referral(dentry, fs_locations);
338 out_free:
339         __free_page(page);
340         kfree(fs_locations);
341 out:
342         dprintk("%s: done\n", __func__);
343         return mnt;
344 }
345 

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