Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/nfs/namespace.c
4 *
5 * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
6 * - Modified by David Howells <dhowells@redhat.com>
7 *
8 * NFS namespace
9 */
10
11#include <linux/module.h>
12#include <linux/dcache.h>
13#include <linux/gfp.h>
14#include <linux/mount.h>
15#include <linux/namei.h>
16#include <linux/nfs_fs.h>
17#include <linux/string.h>
18#include <linux/sunrpc/clnt.h>
19#include <linux/vfs.h>
20#include <linux/sunrpc/gss_api.h>
21#include "internal.h"
22
23#define NFSDBG_FACILITY NFSDBG_VFS
24
25static void nfs_expire_automounts(struct work_struct *work);
26
27static LIST_HEAD(nfs_automount_list);
28static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
29int nfs_mountpoint_expiry_timeout = 500 * HZ;
30
31/*
32 * nfs_path - reconstruct the path given an arbitrary dentry
33 * @base - used to return pointer to the end of devname part of path
34 * @dentry - pointer to dentry
35 * @buffer - result buffer
36 * @buflen - length of buffer
37 * @flags - options (see below)
38 *
39 * Helper function for constructing the server pathname
40 * by arbitrary hashed dentry.
41 *
42 * This is mainly for use in figuring out the path on the
43 * server side when automounting on top of an existing partition
44 * and in generating /proc/mounts and friends.
45 *
46 * Supported flags:
47 * NFS_PATH_CANONICAL: ensure there is exactly one slash after
48 * the original device (export) name
49 * (if unset, the original name is returned verbatim)
50 */
51char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
52 unsigned flags)
53{
54 char *end;
55 int namelen;
56 unsigned seq;
57 const char *base;
58
59rename_retry:
60 end = buffer+buflen;
61 *--end = '\0';
62 buflen--;
63
64 seq = read_seqbegin(&rename_lock);
65 rcu_read_lock();
66 while (1) {
67 spin_lock(&dentry->d_lock);
68 if (IS_ROOT(dentry))
69 break;
70 namelen = dentry->d_name.len;
71 buflen -= namelen + 1;
72 if (buflen < 0)
73 goto Elong_unlock;
74 end -= namelen;
75 memcpy(end, dentry->d_name.name, namelen);
76 *--end = '/';
77 spin_unlock(&dentry->d_lock);
78 dentry = dentry->d_parent;
79 }
80 if (read_seqretry(&rename_lock, seq)) {
81 spin_unlock(&dentry->d_lock);
82 rcu_read_unlock();
83 goto rename_retry;
84 }
85 if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
86 if (--buflen < 0) {
87 spin_unlock(&dentry->d_lock);
88 rcu_read_unlock();
89 goto Elong;
90 }
91 *--end = '/';
92 }
93 *p = end;
94 base = dentry->d_fsdata;
95 if (!base) {
96 spin_unlock(&dentry->d_lock);
97 rcu_read_unlock();
98 WARN_ON(1);
99 return end;
100 }
101 namelen = strlen(base);
102 if (*end == '/') {
103 /* Strip off excess slashes in base string */
104 while (namelen > 0 && base[namelen - 1] == '/')
105 namelen--;
106 }
107 buflen -= namelen;
108 if (buflen < 0) {
109 spin_unlock(&dentry->d_lock);
110 rcu_read_unlock();
111 goto Elong;
112 }
113 end -= namelen;
114 memcpy(end, base, namelen);
115 spin_unlock(&dentry->d_lock);
116 rcu_read_unlock();
117 return end;
118Elong_unlock:
119 spin_unlock(&dentry->d_lock);
120 rcu_read_unlock();
121 if (read_seqretry(&rename_lock, seq))
122 goto rename_retry;
123Elong:
124 return ERR_PTR(-ENAMETOOLONG);
125}
126EXPORT_SYMBOL_GPL(nfs_path);
127
128/*
129 * nfs_d_automount - Handle crossing a mountpoint on the server
130 * @path - The mountpoint
131 *
132 * When we encounter a mountpoint on the server, we want to set up
133 * a mountpoint on the client too, to prevent inode numbers from
134 * colliding, and to allow "df" to work properly.
135 * On NFSv4, we also want to allow for the fact that different
136 * filesystems may be migrated to different servers in a failover
137 * situation, and that different filesystems may want to use
138 * different security flavours.
139 */
140struct vfsmount *nfs_d_automount(struct path *path)
141{
142 struct vfsmount *mnt;
143 struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
144 struct nfs_fh *fh = NULL;
145 struct nfs_fattr *fattr = NULL;
146
147 if (IS_ROOT(path->dentry))
148 return ERR_PTR(-ESTALE);
149
150 mnt = ERR_PTR(-ENOMEM);
151 fh = nfs_alloc_fhandle();
152 fattr = nfs_alloc_fattr();
153 if (fh == NULL || fattr == NULL)
154 goto out;
155
156 mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
157 if (IS_ERR(mnt))
158 goto out;
159
160 mntget(mnt); /* prevent immediate expiration */
161 mnt_set_expiry(mnt, &nfs_automount_list);
162 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
163
164out:
165 nfs_free_fattr(fattr);
166 nfs_free_fhandle(fh);
167 return mnt;
168}
169
170static int
171nfs_namespace_getattr(const struct path *path, struct kstat *stat,
172 u32 request_mask, unsigned int query_flags)
173{
174 if (NFS_FH(d_inode(path->dentry))->size != 0)
175 return nfs_getattr(path, stat, request_mask, query_flags);
176 generic_fillattr(d_inode(path->dentry), stat);
177 return 0;
178}
179
180static int
181nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
182{
183 if (NFS_FH(d_inode(dentry))->size != 0)
184 return nfs_setattr(dentry, attr);
185 return -EACCES;
186}
187
188const struct inode_operations nfs_mountpoint_inode_operations = {
189 .getattr = nfs_getattr,
190 .setattr = nfs_setattr,
191};
192
193const struct inode_operations nfs_referral_inode_operations = {
194 .getattr = nfs_namespace_getattr,
195 .setattr = nfs_namespace_setattr,
196};
197
198static void nfs_expire_automounts(struct work_struct *work)
199{
200 struct list_head *list = &nfs_automount_list;
201
202 mark_mounts_for_expiry(list);
203 if (!list_empty(list))
204 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
205}
206
207void nfs_release_automount_timer(void)
208{
209 if (list_empty(&nfs_automount_list))
210 cancel_delayed_work(&nfs_automount_task);
211}
212
213/*
214 * Clone a mountpoint of the appropriate type
215 */
216static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
217 const char *devname,
218 struct nfs_clone_mount *mountdata)
219{
220 return vfs_submount(mountdata->dentry, &nfs_xdev_fs_type, devname, mountdata);
221}
222
223/**
224 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
225 * @dentry: parent directory
226 * @fh: filehandle for new root dentry
227 * @fattr: attributes for new root inode
228 * @authflavor: security flavor to use when performing the mount
229 *
230 */
231struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
232 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
233{
234 struct nfs_clone_mount mountdata = {
235 .sb = dentry->d_sb,
236 .dentry = dentry,
237 .fh = fh,
238 .fattr = fattr,
239 .authflavor = authflavor,
240 };
241 struct vfsmount *mnt;
242 char *page = (char *) __get_free_page(GFP_USER);
243 char *devname;
244
245 if (page == NULL)
246 return ERR_PTR(-ENOMEM);
247
248 devname = nfs_devname(dentry, page, PAGE_SIZE);
249 if (IS_ERR(devname))
250 mnt = ERR_CAST(devname);
251 else
252 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
253
254 free_page((unsigned long)page);
255 return mnt;
256}
257EXPORT_SYMBOL_GPL(nfs_do_submount);
258
259struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
260 struct nfs_fh *fh, struct nfs_fattr *fattr)
261{
262 int err;
263 struct dentry *parent = dget_parent(dentry);
264
265 /* Look it up again to get its attributes */
266 err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
267 dput(parent);
268 if (err != 0)
269 return ERR_PTR(err);
270
271 return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
272}
273EXPORT_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
29/*
30 * nfs_path - reconstruct the path given an arbitrary dentry
31 * @base - used to return pointer to the end of devname part of path
32 * @dentry - pointer to dentry
33 * @buffer - result buffer
34 * @buflen - length of buffer
35 *
36 * Helper function for constructing the server pathname
37 * by arbitrary hashed dentry.
38 *
39 * This is mainly for use in figuring out the path on the
40 * server side when automounting on top of an existing partition
41 * and in generating /proc/mounts and friends.
42 */
43char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen)
44{
45 char *end;
46 int namelen;
47 unsigned seq;
48 const char *base;
49
50rename_retry:
51 end = buffer+buflen;
52 *--end = '\0';
53 buflen--;
54
55 seq = read_seqbegin(&rename_lock);
56 rcu_read_lock();
57 while (1) {
58 spin_lock(&dentry->d_lock);
59 if (IS_ROOT(dentry))
60 break;
61 namelen = dentry->d_name.len;
62 buflen -= namelen + 1;
63 if (buflen < 0)
64 goto Elong_unlock;
65 end -= namelen;
66 memcpy(end, dentry->d_name.name, namelen);
67 *--end = '/';
68 spin_unlock(&dentry->d_lock);
69 dentry = dentry->d_parent;
70 }
71 if (read_seqretry(&rename_lock, seq)) {
72 spin_unlock(&dentry->d_lock);
73 rcu_read_unlock();
74 goto rename_retry;
75 }
76 if (*end != '/') {
77 if (--buflen < 0) {
78 spin_unlock(&dentry->d_lock);
79 rcu_read_unlock();
80 goto Elong;
81 }
82 *--end = '/';
83 }
84 *p = end;
85 base = dentry->d_fsdata;
86 if (!base) {
87 spin_unlock(&dentry->d_lock);
88 rcu_read_unlock();
89 WARN_ON(1);
90 return end;
91 }
92 namelen = strlen(base);
93 /* Strip off excess slashes in base string */
94 while (namelen > 0 && base[namelen - 1] == '/')
95 namelen--;
96 buflen -= namelen;
97 if (buflen < 0) {
98 spin_unlock(&dentry->d_lock);
99 rcu_read_unlock();
100 goto Elong;
101 }
102 end -= namelen;
103 memcpy(end, base, namelen);
104 spin_unlock(&dentry->d_lock);
105 rcu_read_unlock();
106 return end;
107Elong_unlock:
108 spin_unlock(&dentry->d_lock);
109 rcu_read_unlock();
110 if (read_seqretry(&rename_lock, seq))
111 goto rename_retry;
112Elong:
113 return ERR_PTR(-ENAMETOOLONG);
114}
115
116/*
117 * nfs_d_automount - Handle crossing a mountpoint on the server
118 * @path - The mountpoint
119 *
120 * When we encounter a mountpoint on the server, we want to set up
121 * a mountpoint on the client too, to prevent inode numbers from
122 * colliding, and to allow "df" to work properly.
123 * On NFSv4, we also want to allow for the fact that different
124 * filesystems may be migrated to different servers in a failover
125 * situation, and that different filesystems may want to use
126 * different security flavours.
127 */
128struct vfsmount *nfs_d_automount(struct path *path)
129{
130 struct vfsmount *mnt;
131 struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
132 struct nfs_fh *fh = NULL;
133 struct nfs_fattr *fattr = NULL;
134
135 dprintk("--> nfs_d_automount()\n");
136
137 mnt = ERR_PTR(-ESTALE);
138 if (IS_ROOT(path->dentry))
139 goto out_nofree;
140
141 mnt = ERR_PTR(-ENOMEM);
142 fh = nfs_alloc_fhandle();
143 fattr = nfs_alloc_fattr();
144 if (fh == NULL || fattr == NULL)
145 goto out;
146
147 dprintk("%s: enter\n", __func__);
148
149 mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
150 if (IS_ERR(mnt))
151 goto out;
152
153 dprintk("%s: done, success\n", __func__);
154 mntget(mnt); /* prevent immediate expiration */
155 mnt_set_expiry(mnt, &nfs_automount_list);
156 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
157
158out:
159 nfs_free_fattr(fattr);
160 nfs_free_fhandle(fh);
161out_nofree:
162 if (IS_ERR(mnt))
163 dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
164 else
165 dprintk("<-- %s() = %p\n", __func__, mnt);
166 return mnt;
167}
168
169const struct inode_operations nfs_mountpoint_inode_operations = {
170 .getattr = nfs_getattr,
171};
172
173const struct inode_operations nfs_referral_inode_operations = {
174};
175
176static void nfs_expire_automounts(struct work_struct *work)
177{
178 struct list_head *list = &nfs_automount_list;
179
180 mark_mounts_for_expiry(list);
181 if (!list_empty(list))
182 schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
183}
184
185void nfs_release_automount_timer(void)
186{
187 if (list_empty(&nfs_automount_list))
188 cancel_delayed_work(&nfs_automount_task);
189}
190
191/*
192 * Clone a mountpoint of the appropriate type
193 */
194static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
195 const char *devname,
196 struct nfs_clone_mount *mountdata)
197{
198#ifdef CONFIG_NFS_V4
199 struct vfsmount *mnt = ERR_PTR(-EINVAL);
200 switch (server->nfs_client->rpc_ops->version) {
201 case 2:
202 case 3:
203 mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
204 break;
205 case 4:
206 mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
207 }
208 return mnt;
209#else
210 return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
211#endif
212}
213
214/**
215 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
216 * @dentry - parent directory
217 * @fh - filehandle for new root dentry
218 * @fattr - attributes for new root inode
219 * @authflavor - security flavor to use when performing the mount
220 *
221 */
222struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
223 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
224{
225 struct nfs_clone_mount mountdata = {
226 .sb = dentry->d_sb,
227 .dentry = dentry,
228 .fh = fh,
229 .fattr = fattr,
230 .authflavor = authflavor,
231 };
232 struct vfsmount *mnt = ERR_PTR(-ENOMEM);
233 char *page = (char *) __get_free_page(GFP_USER);
234 char *devname;
235
236 dprintk("--> nfs_do_submount()\n");
237
238 dprintk("%s: submounting on %s/%s\n", __func__,
239 dentry->d_parent->d_name.name,
240 dentry->d_name.name);
241 if (page == NULL)
242 goto out;
243 devname = nfs_devname(dentry, page, PAGE_SIZE);
244 mnt = (struct vfsmount *)devname;
245 if (IS_ERR(devname))
246 goto free_page;
247 mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
248free_page:
249 free_page((unsigned long)page);
250out:
251 dprintk("%s: done\n", __func__);
252
253 dprintk("<-- nfs_do_submount() = %p\n", mnt);
254 return mnt;
255}
256
257struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
258 struct nfs_fh *fh, struct nfs_fattr *fattr)
259{
260 int err;
261 struct dentry *parent = dget_parent(dentry);
262
263 /* Look it up again to get its attributes */
264 err = server->nfs_client->rpc_ops->lookup(parent->d_inode, &dentry->d_name, fh, fattr);
265 dput(parent);
266 if (err != 0)
267 return ERR_PTR(err);
268
269 return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
270}