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1/*
2 * linux/fs/nfs/namespace.c
3 *
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
5 * - Modified by David Howells <dhowells@redhat.com>
6 *
7 * NFS namespace
8 */
9
10#include <linux/module.h>
11#include <linux/dcache.h>
12#include <linux/gfp.h>
13#include <linux/mount.h>
14#include <linux/namei.h>
15#include <linux/nfs_fs.h>
16#include <linux/string.h>
17#include <linux/sunrpc/clnt.h>
18#include <linux/vfs.h>
19#include <linux/sunrpc/gss_api.h>
20#include "internal.h"
21
22#define NFSDBG_FACILITY NFSDBG_VFS
23
24static void nfs_expire_automounts(struct work_struct *work);
25
26static LIST_HEAD(nfs_automount_list);
27static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
28int nfs_mountpoint_expiry_timeout = 500 * HZ;
29
30/*
31 * nfs_path - reconstruct the path given an arbitrary dentry
32 * @base - used to return pointer to the end of devname part of path
33 * @dentry - pointer to dentry
34 * @buffer - result buffer
35 * @buflen - length of buffer
36 * @flags - options (see below)
37 *
38 * Helper function for constructing the server pathname
39 * by arbitrary hashed dentry.
40 *
41 * This is mainly for use in figuring out the path on the
42 * server side when automounting on top of an existing partition
43 * and in generating /proc/mounts and friends.
44 *
45 * Supported flags:
46 * NFS_PATH_CANONICAL: ensure there is exactly one slash after
47 * the original device (export) name
48 * (if unset, the original name is returned verbatim)
49 */
50char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
51 unsigned flags)
52{
53 char *end;
54 int namelen;
55 unsigned seq;
56 const char *base;
57
58rename_retry:
59 end = buffer+buflen;
60 *--end = '\0';
61 buflen--;
62
63 seq = read_seqbegin(&rename_lock);
64 rcu_read_lock();
65 while (1) {
66 spin_lock(&dentry->d_lock);
67 if (IS_ROOT(dentry))
68 break;
69 namelen = dentry->d_name.len;
70 buflen -= namelen + 1;
71 if (buflen < 0)
72 goto Elong_unlock;
73 end -= namelen;
74 memcpy(end, dentry->d_name.name, namelen);
75 *--end = '/';
76 spin_unlock(&dentry->d_lock);
77 dentry = dentry->d_parent;
78 }
79 if (read_seqretry(&rename_lock, seq)) {
80 spin_unlock(&dentry->d_lock);
81 rcu_read_unlock();
82 goto rename_retry;
83 }
84 if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
85 if (--buflen < 0) {
86 spin_unlock(&dentry->d_lock);
87 rcu_read_unlock();
88 goto Elong;
89 }
90 *--end = '/';
91 }
92 *p = end;
93 base = dentry->d_fsdata;
94 if (!base) {
95 spin_unlock(&dentry->d_lock);
96 rcu_read_unlock();
97 WARN_ON(1);
98 return end;
99 }
100 namelen = strlen(base);
101 if (flags & NFS_PATH_CANONICAL) {
102 /* Strip off excess slashes in base string */
103 while (namelen > 0 && base[namelen - 1] == '/')
104 namelen--;
105 }
106 buflen -= namelen;
107 if (buflen < 0) {
108 spin_unlock(&dentry->d_lock);
109 rcu_read_unlock();
110 goto Elong;
111 }
112 end -= namelen;
113 memcpy(end, base, namelen);
114 spin_unlock(&dentry->d_lock);
115 rcu_read_unlock();
116 return end;
117Elong_unlock:
118 spin_unlock(&dentry->d_lock);
119 rcu_read_unlock();
120 if (read_seqretry(&rename_lock, seq))
121 goto rename_retry;
122Elong:
123 return ERR_PTR(-ENAMETOOLONG);
124}
125EXPORT_SYMBOL_GPL(nfs_path);
126
127/*
128 * nfs_d_automount - Handle crossing a mountpoint on the server
129 * @path - The mountpoint
130 *
131 * When we encounter a mountpoint on the server, we want to set up
132 * a mountpoint on the client too, to prevent inode numbers from
133 * colliding, and to allow "df" to work properly.
134 * On NFSv4, we also want to allow for the fact that different
135 * filesystems may be migrated to different servers in a failover
136 * situation, and that different filesystems may want to use
137 * different security flavours.
138 */
139struct vfsmount *nfs_d_automount(struct path *path)
140{
141 struct vfsmount *mnt;
142 struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
143 struct nfs_fh *fh = NULL;
144 struct nfs_fattr *fattr = NULL;
145
146 dprintk("--> nfs_d_automount()\n");
147
148 mnt = ERR_PTR(-ESTALE);
149 if (IS_ROOT(path->dentry))
150 goto out_nofree;
151
152 mnt = ERR_PTR(-ENOMEM);
153 fh = nfs_alloc_fhandle();
154 fattr = nfs_alloc_fattr();
155 if (fh == NULL || fattr == NULL)
156 goto out;
157
158 dprintk("%s: enter\n", __func__);
159
160 mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
161 if (IS_ERR(mnt))
162 goto out;
163
164 dprintk("%s: done, success\n", __func__);
165 mntget(mnt); /* prevent immediate expiration */
166 mnt_set_expiry(mnt, &nfs_automount_list);
167 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
168
169out:
170 nfs_free_fattr(fattr);
171 nfs_free_fhandle(fh);
172out_nofree:
173 if (IS_ERR(mnt))
174 dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
175 else
176 dprintk("<-- %s() = %p\n", __func__, mnt);
177 return mnt;
178}
179
180static int
181nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
182{
183 if (NFS_FH(d_inode(dentry))->size != 0)
184 return nfs_getattr(mnt, dentry, stat);
185 generic_fillattr(d_inode(dentry), stat);
186 return 0;
187}
188
189static int
190nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
191{
192 if (NFS_FH(d_inode(dentry))->size != 0)
193 return nfs_setattr(dentry, attr);
194 return -EACCES;
195}
196
197const struct inode_operations nfs_mountpoint_inode_operations = {
198 .getattr = nfs_getattr,
199 .setattr = nfs_setattr,
200};
201
202const struct inode_operations nfs_referral_inode_operations = {
203 .getattr = nfs_namespace_getattr,
204 .setattr = nfs_namespace_setattr,
205};
206
207static void nfs_expire_automounts(struct work_struct *work)
208{
209 struct list_head *list = &nfs_automount_list;
210
211 mark_mounts_for_expiry(list);
212 if (!list_empty(list))
213 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
214}
215
216void nfs_release_automount_timer(void)
217{
218 if (list_empty(&nfs_automount_list))
219 cancel_delayed_work(&nfs_automount_task);
220}
221
222/*
223 * Clone a mountpoint of the appropriate type
224 */
225static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
226 const char *devname,
227 struct nfs_clone_mount *mountdata)
228{
229 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
230}
231
232/**
233 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
234 * @dentry - parent directory
235 * @fh - filehandle for new root dentry
236 * @fattr - attributes for new root inode
237 * @authflavor - security flavor to use when performing the mount
238 *
239 */
240struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
241 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
242{
243 struct nfs_clone_mount mountdata = {
244 .sb = dentry->d_sb,
245 .dentry = dentry,
246 .fh = fh,
247 .fattr = fattr,
248 .authflavor = authflavor,
249 };
250 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
251 char *page = (char *) __get_free_page(GFP_USER);
252 char *devname;
253
254 dprintk("--> nfs_do_submount()\n");
255
256 dprintk("%s: submounting on %pd2\n", __func__,
257 dentry);
258 if (page == NULL)
259 goto out;
260 devname = nfs_devname(dentry, page, PAGE_SIZE);
261 mnt = (struct vfsmount *)devname;
262 if (IS_ERR(devname))
263 goto free_page;
264 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
265free_page:
266 free_page((unsigned long)page);
267out:
268 dprintk("%s: done\n", __func__);
269
270 dprintk("<-- nfs_do_submount() = %p\n", mnt);
271 return mnt;
272}
273EXPORT_SYMBOL_GPL(nfs_do_submount);
274
275struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
276 struct nfs_fh *fh, struct nfs_fattr *fattr)
277{
278 int err;
279 struct dentry *parent = dget_parent(dentry);
280
281 /* Look it up again to get its attributes */
282 err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
283 dput(parent);
284 if (err != 0)
285 return ERR_PTR(err);
286
287 return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
288}
289EXPORT_SYMBOL_GPL(nfs_submount);
1/*
2 * linux/fs/nfs/namespace.c
3 *
4 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
5 * - Modified by David Howells <dhowells@redhat.com>
6 *
7 * NFS namespace
8 */
9
10#include <linux/dcache.h>
11#include <linux/gfp.h>
12#include <linux/mount.h>
13#include <linux/namei.h>
14#include <linux/nfs_fs.h>
15#include <linux/string.h>
16#include <linux/sunrpc/clnt.h>
17#include <linux/vfs.h>
18#include <linux/sunrpc/gss_api.h>
19#include "internal.h"
20
21#define NFSDBG_FACILITY NFSDBG_VFS
22
23static void nfs_expire_automounts(struct work_struct *work);
24
25static LIST_HEAD(nfs_automount_list);
26static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
27int nfs_mountpoint_expiry_timeout = 500 * HZ;
28
29static struct vfsmount *nfs_do_submount(struct dentry *dentry,
30 struct nfs_fh *fh,
31 struct nfs_fattr *fattr,
32 rpc_authflavor_t authflavor);
33
34/*
35 * nfs_path - reconstruct the path given an arbitrary dentry
36 * @base - used to return pointer to the end of devname part of path
37 * @dentry - pointer to dentry
38 * @buffer - result buffer
39 * @buflen - length of buffer
40 *
41 * Helper function for constructing the server pathname
42 * by arbitrary hashed dentry.
43 *
44 * This is mainly for use in figuring out the path on the
45 * server side when automounting on top of an existing partition
46 * and in generating /proc/mounts and friends.
47 */
48char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
49{
50 char *end;
51 int namelen;
52 unsigned seq;
53 const char *base;
54
55rename_retry:
56 end = buffer+buflen;
57 *--end = '\0';
58 buflen--;
59
60 seq = read_seqbegin(&rename_lock);
61 rcu_read_lock();
62 while (1) {
63 spin_lock(&dentry->d_lock);
64 if (IS_ROOT(dentry))
65 break;
66 namelen = dentry->d_name.len;
67 buflen -= namelen + 1;
68 if (buflen < 0)
69 goto Elong_unlock;
70 end -= namelen;
71 memcpy(end, dentry->d_name.name, namelen);
72 *--end = '/';
73 spin_unlock(&dentry->d_lock);
74 dentry = dentry->d_parent;
75 }
76 if (read_seqretry(&rename_lock, seq)) {
77 spin_unlock(&dentry->d_lock);
78 rcu_read_unlock();
79 goto rename_retry;
80 }
81 if (*end != '/') {
82 if (--buflen < 0) {
83 spin_unlock(&dentry->d_lock);
84 rcu_read_unlock();
85 goto Elong;
86 }
87 *--end = '/';
88 }
89 *p = end;
90 base = dentry->d_fsdata;
91 if (!base) {
92 spin_unlock(&dentry->d_lock);
93 rcu_read_unlock();
94 WARN_ON(1);
95 return end;
96 }
97 namelen = strlen(base);
98 /* Strip off excess slashes in base string */
99 while (namelen > 0 && base[namelen - 1] == '/')
100 namelen--;
101 buflen -= namelen;
102 if (buflen < 0) {
103 spin_unlock(&dentry->d_lock);
104 rcu_read_unlock();
105 goto Elong;
106 }
107 end -= namelen;
108 memcpy(end, base, namelen);
109 spin_unlock(&dentry->d_lock);
110 rcu_read_unlock();
111 return end;
112Elong_unlock:
113 spin_unlock(&dentry->d_lock);
114 rcu_read_unlock();
115 if (read_seqretry(&rename_lock, seq))
116 goto rename_retry;
117Elong:
118 return ERR_PTR(-ENAMETOOLONG);
119}
120
121#ifdef CONFIG_NFS_V4
122rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors)
123{
124 struct gss_api_mech *mech;
125 struct xdr_netobj oid;
126 int i;
127 rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
128
129 for (i = 0; i < flavors->num_flavors; i++) {
130 struct nfs4_secinfo_flavor *flavor;
131 flavor = &flavors->flavors[i];
132
133 if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) {
134 pseudoflavor = flavor->flavor;
135 break;
136 } else if (flavor->flavor == RPC_AUTH_GSS) {
137 oid.len = flavor->gss.sec_oid4.len;
138 oid.data = flavor->gss.sec_oid4.data;
139 mech = gss_mech_get_by_OID(&oid);
140 if (!mech)
141 continue;
142 pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service);
143 gss_mech_put(mech);
144 break;
145 }
146 }
147
148 return pseudoflavor;
149}
150
151static int nfs_negotiate_security(const struct dentry *parent,
152 const struct dentry *dentry,
153 rpc_authflavor_t *flavor)
154{
155 struct page *page;
156 struct nfs4_secinfo_flavors *flavors;
157 int (*secinfo)(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *);
158 int ret = -EPERM;
159
160 secinfo = NFS_PROTO(parent->d_inode)->secinfo;
161 if (secinfo != NULL) {
162 page = alloc_page(GFP_KERNEL);
163 if (!page) {
164 ret = -ENOMEM;
165 goto out;
166 }
167 flavors = page_address(page);
168 ret = secinfo(parent->d_inode, &dentry->d_name, flavors);
169 *flavor = nfs_find_best_sec(flavors);
170 put_page(page);
171 }
172
173out:
174 return ret;
175}
176
177static int nfs_lookup_with_sec(struct nfs_server *server, struct dentry *parent,
178 struct dentry *dentry, struct path *path,
179 struct nfs_fh *fh, struct nfs_fattr *fattr,
180 rpc_authflavor_t *flavor)
181{
182 struct rpc_clnt *clone;
183 struct rpc_auth *auth;
184 int err;
185
186 err = nfs_negotiate_security(parent, path->dentry, flavor);
187 if (err < 0)
188 goto out;
189 clone = rpc_clone_client(server->client);
190 auth = rpcauth_create(*flavor, clone);
191 if (!auth) {
192 err = -EIO;
193 goto out_shutdown;
194 }
195 err = server->nfs_client->rpc_ops->lookup(clone, parent->d_inode,
196 &path->dentry->d_name,
197 fh, fattr);
198out_shutdown:
199 rpc_shutdown_client(clone);
200out:
201 return err;
202}
203#else /* CONFIG_NFS_V4 */
204static inline int nfs_lookup_with_sec(struct nfs_server *server,
205 struct dentry *parent, struct dentry *dentry,
206 struct path *path, struct nfs_fh *fh,
207 struct nfs_fattr *fattr,
208 rpc_authflavor_t *flavor)
209{
210 return -EPERM;
211}
212#endif /* CONFIG_NFS_V4 */
213
214/*
215 * nfs_d_automount - Handle crossing a mountpoint on the server
216 * @path - The mountpoint
217 *
218 * When we encounter a mountpoint on the server, we want to set up
219 * a mountpoint on the client too, to prevent inode numbers from
220 * colliding, and to allow "df" to work properly.
221 * On NFSv4, we also want to allow for the fact that different
222 * filesystems may be migrated to different servers in a failover
223 * situation, and that different filesystems may want to use
224 * different security flavours.
225 */
226struct vfsmount *nfs_d_automount(struct path *path)
227{
228 struct vfsmount *mnt;
229 struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
230 struct dentry *parent;
231 struct nfs_fh *fh = NULL;
232 struct nfs_fattr *fattr = NULL;
233 int err;
234 rpc_authflavor_t flavor = RPC_AUTH_UNIX;
235
236 dprintk("--> nfs_d_automount()\n");
237
238 mnt = ERR_PTR(-ESTALE);
239 if (IS_ROOT(path->dentry))
240 goto out_nofree;
241
242 mnt = ERR_PTR(-ENOMEM);
243 fh = nfs_alloc_fhandle();
244 fattr = nfs_alloc_fattr();
245 if (fh == NULL || fattr == NULL)
246 goto out;
247
248 dprintk("%s: enter\n", __func__);
249
250 /* Look it up again to get its attributes */
251 parent = dget_parent(path->dentry);
252 err = server->nfs_client->rpc_ops->lookup(server->client, parent->d_inode,
253 &path->dentry->d_name,
254 fh, fattr);
255 if (err == -EPERM && NFS_PROTO(parent->d_inode)->secinfo != NULL)
256 err = nfs_lookup_with_sec(server, parent, path->dentry, path, fh, fattr, &flavor);
257 dput(parent);
258 if (err != 0) {
259 mnt = ERR_PTR(err);
260 goto out;
261 }
262
263 if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
264 mnt = nfs_do_refmount(path->dentry);
265 else
266 mnt = nfs_do_submount(path->dentry, fh, fattr, flavor);
267 if (IS_ERR(mnt))
268 goto out;
269
270 dprintk("%s: done, success\n", __func__);
271 mntget(mnt); /* prevent immediate expiration */
272 mnt_set_expiry(mnt, &nfs_automount_list);
273 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
274
275out:
276 nfs_free_fattr(fattr);
277 nfs_free_fhandle(fh);
278out_nofree:
279 dprintk("<-- nfs_follow_mountpoint() = %p\n", mnt);
280 return mnt;
281}
282
283const struct inode_operations nfs_mountpoint_inode_operations = {
284 .getattr = nfs_getattr,
285};
286
287const struct inode_operations nfs_referral_inode_operations = {
288};
289
290static void nfs_expire_automounts(struct work_struct *work)
291{
292 struct list_head *list = &nfs_automount_list;
293
294 mark_mounts_for_expiry(list);
295 if (!list_empty(list))
296 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
297}
298
299void nfs_release_automount_timer(void)
300{
301 if (list_empty(&nfs_automount_list))
302 cancel_delayed_work(&nfs_automount_task);
303}
304
305/*
306 * Clone a mountpoint of the appropriate type
307 */
308static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
309 const char *devname,
310 struct nfs_clone_mount *mountdata)
311{
312#ifdef CONFIG_NFS_V4
313 struct vfsmount *mnt = ERR_PTR(-EINVAL);
314 switch (server->nfs_client->rpc_ops->version) {
315 case 2:
316 case 3:
317 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
318 break;
319 case 4:
320 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
321 }
322 return mnt;
323#else
324 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
325#endif
326}
327
328/**
329 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
330 * @dentry - parent directory
331 * @fh - filehandle for new root dentry
332 * @fattr - attributes for new root inode
333 * @authflavor - security flavor to use when performing the mount
334 *
335 */
336static struct vfsmount *nfs_do_submount(struct dentry *dentry,
337 struct nfs_fh *fh,
338 struct nfs_fattr *fattr,
339 rpc_authflavor_t authflavor)
340{
341 struct nfs_clone_mount mountdata = {
342 .sb = dentry->d_sb,
343 .dentry = dentry,
344 .fh = fh,
345 .fattr = fattr,
346 .authflavor = authflavor,
347 };
348 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
349 char *page = (char *) __get_free_page(GFP_USER);
350 char *devname;
351
352 dprintk("--> nfs_do_submount()\n");
353
354 dprintk("%s: submounting on %s/%s\n", __func__,
355 dentry->d_parent->d_name.name,
356 dentry->d_name.name);
357 if (page == NULL)
358 goto out;
359 devname = nfs_devname(dentry, page, PAGE_SIZE);
360 mnt = (struct vfsmount *)devname;
361 if (IS_ERR(devname))
362 goto free_page;
363 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
364free_page:
365 free_page((unsigned long)page);
366out:
367 dprintk("%s: done\n", __func__);
368
369 dprintk("<-- nfs_do_submount() = %p\n", mnt);
370 return mnt;
371}