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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* mountpoint management
3 *
4 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/fs.h>
12#include <linux/pagemap.h>
13#include <linux/mount.h>
14#include <linux/namei.h>
15#include <linux/gfp.h>
16#include <linux/fs_context.h>
17#include "internal.h"
18
19
20static struct dentry *afs_mntpt_lookup(struct inode *dir,
21 struct dentry *dentry,
22 unsigned int flags);
23static int afs_mntpt_open(struct inode *inode, struct file *file);
24static void afs_mntpt_expiry_timed_out(struct work_struct *work);
25
26const struct file_operations afs_mntpt_file_operations = {
27 .open = afs_mntpt_open,
28 .llseek = noop_llseek,
29};
30
31const struct inode_operations afs_mntpt_inode_operations = {
32 .lookup = afs_mntpt_lookup,
33 .readlink = page_readlink,
34 .getattr = afs_getattr,
35};
36
37const struct inode_operations afs_autocell_inode_operations = {
38 .getattr = afs_getattr,
39};
40
41static LIST_HEAD(afs_vfsmounts);
42static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
43
44static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
45
46static const char afs_root_volume[] = "root.cell";
47
48/*
49 * no valid lookup procedure on this sort of dir
50 */
51static struct dentry *afs_mntpt_lookup(struct inode *dir,
52 struct dentry *dentry,
53 unsigned int flags)
54{
55 _enter("%p,%p{%pd2}", dir, dentry, dentry);
56 return ERR_PTR(-EREMOTE);
57}
58
59/*
60 * no valid open procedure on this sort of dir
61 */
62static int afs_mntpt_open(struct inode *inode, struct file *file)
63{
64 _enter("%p,%p{%pD2}", inode, file, file);
65 return -EREMOTE;
66}
67
68/*
69 * Set the parameters for the proposed superblock.
70 */
71static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
72{
73 struct afs_fs_context *ctx = fc->fs_private;
74 struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb);
75 struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt));
76 struct afs_cell *cell;
77 const char *p;
78 int ret;
79
80 if (fc->net_ns != src_as->net_ns) {
81 put_net(fc->net_ns);
82 fc->net_ns = get_net(src_as->net_ns);
83 }
84
85 if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) {
86 ctx->type = AFSVL_RWVOL;
87 ctx->force = true;
88 }
89 if (ctx->cell) {
90 afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt);
91 ctx->cell = NULL;
92 }
93 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
94 /* if the directory is a pseudo directory, use the d_name */
95 unsigned size = mntpt->d_name.len;
96
97 if (size < 2)
98 return -ENOENT;
99
100 p = mntpt->d_name.name;
101 if (mntpt->d_name.name[0] == '.') {
102 size--;
103 p++;
104 ctx->type = AFSVL_RWVOL;
105 ctx->force = true;
106 }
107 if (size > AFS_MAXCELLNAME)
108 return -ENAMETOOLONG;
109
110 cell = afs_lookup_cell(ctx->net, p, size, NULL, false);
111 if (IS_ERR(cell)) {
112 pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt);
113 return PTR_ERR(cell);
114 }
115 ctx->cell = cell;
116
117 ctx->volname = afs_root_volume;
118 ctx->volnamesz = sizeof(afs_root_volume) - 1;
119 } else {
120 /* read the contents of the AFS special symlink */
121 struct page *page;
122 loff_t size = i_size_read(d_inode(mntpt));
123 char *buf;
124
125 if (src_as->cell)
126 ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);
127
128 if (size < 2 || size > PAGE_SIZE - 1)
129 return -EINVAL;
130
131 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
132 if (IS_ERR(page))
133 return PTR_ERR(page);
134
135 buf = kmap(page);
136 ret = -EINVAL;
137 if (buf[size - 1] == '.')
138 ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
139 kunmap(page);
140 put_page(page);
141 if (ret < 0)
142 return ret;
143 }
144
145 return 0;
146}
147
148/*
149 * create a vfsmount to be automounted
150 */
151static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
152{
153 struct fs_context *fc;
154 struct vfsmount *mnt;
155 int ret;
156
157 BUG_ON(!d_inode(mntpt));
158
159 fc = fs_context_for_submount(&afs_fs_type, mntpt);
160 if (IS_ERR(fc))
161 return ERR_CAST(fc);
162
163 ret = afs_mntpt_set_params(fc, mntpt);
164 if (!ret)
165 mnt = fc_mount(fc);
166 else
167 mnt = ERR_PTR(ret);
168
169 put_fs_context(fc);
170 return mnt;
171}
172
173/*
174 * handle an automount point
175 */
176struct vfsmount *afs_d_automount(struct path *path)
177{
178 struct vfsmount *newmnt;
179
180 _enter("{%pd}", path->dentry);
181
182 newmnt = afs_mntpt_do_automount(path->dentry);
183 if (IS_ERR(newmnt))
184 return newmnt;
185
186 mntget(newmnt); /* prevent immediate expiration */
187 mnt_set_expiry(newmnt, &afs_vfsmounts);
188 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
189 afs_mntpt_expiry_timeout * HZ);
190 _leave(" = %p", newmnt);
191 return newmnt;
192}
193
194/*
195 * handle mountpoint expiry timer going off
196 */
197static void afs_mntpt_expiry_timed_out(struct work_struct *work)
198{
199 _enter("");
200
201 if (!list_empty(&afs_vfsmounts)) {
202 mark_mounts_for_expiry(&afs_vfsmounts);
203 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
204 afs_mntpt_expiry_timeout * HZ);
205 }
206
207 _leave("");
208}
209
210/*
211 * kill the AFS mountpoint timer if it's still running
212 */
213void afs_mntpt_kill_timer(void)
214{
215 _enter("");
216
217 ASSERT(list_empty(&afs_vfsmounts));
218 cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
219}
1/* mountpoint management
2 *
3 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/fs.h>
16#include <linux/pagemap.h>
17#include <linux/mount.h>
18#include <linux/namei.h>
19#include <linux/gfp.h>
20#include "internal.h"
21
22
23static struct dentry *afs_mntpt_lookup(struct inode *dir,
24 struct dentry *dentry,
25 unsigned int flags);
26static int afs_mntpt_open(struct inode *inode, struct file *file);
27static void afs_mntpt_expiry_timed_out(struct work_struct *work);
28
29const struct file_operations afs_mntpt_file_operations = {
30 .open = afs_mntpt_open,
31 .llseek = noop_llseek,
32};
33
34const struct inode_operations afs_mntpt_inode_operations = {
35 .lookup = afs_mntpt_lookup,
36 .readlink = page_readlink,
37 .getattr = afs_getattr,
38};
39
40const struct inode_operations afs_autocell_inode_operations = {
41 .getattr = afs_getattr,
42};
43
44static LIST_HEAD(afs_vfsmounts);
45static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);
46
47static unsigned long afs_mntpt_expiry_timeout = 10 * 60;
48
49/*
50 * check a symbolic link to see whether it actually encodes a mountpoint
51 * - sets the AFS_VNODE_MOUNTPOINT flag on the vnode appropriately
52 */
53int afs_mntpt_check_symlink(struct afs_vnode *vnode, struct key *key)
54{
55 struct page *page;
56 size_t size;
57 char *buf;
58 int ret;
59
60 _enter("{%x:%u,%u}",
61 vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
62
63 /* read the contents of the symlink into the pagecache */
64 page = read_cache_page(AFS_VNODE_TO_I(vnode)->i_mapping, 0,
65 afs_page_filler, key);
66 if (IS_ERR(page)) {
67 ret = PTR_ERR(page);
68 goto out;
69 }
70
71 ret = -EIO;
72 if (PageError(page))
73 goto out_free;
74
75 buf = kmap(page);
76
77 /* examine the symlink's contents */
78 size = vnode->status.size;
79 _debug("symlink to %*.*s", (int) size, (int) size, buf);
80
81 if (size > 2 &&
82 (buf[0] == '%' || buf[0] == '#') &&
83 buf[size - 1] == '.'
84 ) {
85 _debug("symlink is a mountpoint");
86 spin_lock(&vnode->lock);
87 set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
88 vnode->vfs_inode.i_flags |= S_AUTOMOUNT;
89 spin_unlock(&vnode->lock);
90 }
91
92 ret = 0;
93
94 kunmap(page);
95out_free:
96 put_page(page);
97out:
98 _leave(" = %d", ret);
99 return ret;
100}
101
102/*
103 * no valid lookup procedure on this sort of dir
104 */
105static struct dentry *afs_mntpt_lookup(struct inode *dir,
106 struct dentry *dentry,
107 unsigned int flags)
108{
109 _enter("%p,%p{%pd2}", dir, dentry, dentry);
110 return ERR_PTR(-EREMOTE);
111}
112
113/*
114 * no valid open procedure on this sort of dir
115 */
116static int afs_mntpt_open(struct inode *inode, struct file *file)
117{
118 _enter("%p,%p{%pD2}", inode, file, file);
119 return -EREMOTE;
120}
121
122/*
123 * create a vfsmount to be automounted
124 */
125static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
126{
127 struct afs_super_info *super;
128 struct vfsmount *mnt;
129 struct afs_vnode *vnode;
130 struct page *page;
131 char *devname, *options;
132 bool rwpath = false;
133 int ret;
134
135 _enter("{%pd}", mntpt);
136
137 BUG_ON(!d_inode(mntpt));
138
139 ret = -ENOMEM;
140 devname = (char *) get_zeroed_page(GFP_KERNEL);
141 if (!devname)
142 goto error_no_devname;
143
144 options = (char *) get_zeroed_page(GFP_KERNEL);
145 if (!options)
146 goto error_no_options;
147
148 vnode = AFS_FS_I(d_inode(mntpt));
149 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
150 /* if the directory is a pseudo directory, use the d_name */
151 static const char afs_root_cell[] = ":root.cell.";
152 unsigned size = mntpt->d_name.len;
153
154 ret = -ENOENT;
155 if (size < 2 || size > AFS_MAXCELLNAME)
156 goto error_no_page;
157
158 if (mntpt->d_name.name[0] == '.') {
159 devname[0] = '#';
160 memcpy(devname + 1, mntpt->d_name.name, size - 1);
161 memcpy(devname + size, afs_root_cell,
162 sizeof(afs_root_cell));
163 rwpath = true;
164 } else {
165 devname[0] = '%';
166 memcpy(devname + 1, mntpt->d_name.name, size);
167 memcpy(devname + size + 1, afs_root_cell,
168 sizeof(afs_root_cell));
169 }
170 } else {
171 /* read the contents of the AFS special symlink */
172 loff_t size = i_size_read(d_inode(mntpt));
173 char *buf;
174
175 ret = -EINVAL;
176 if (size > PAGE_SIZE - 1)
177 goto error_no_page;
178
179 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
180 if (IS_ERR(page)) {
181 ret = PTR_ERR(page);
182 goto error_no_page;
183 }
184
185 ret = -EIO;
186 if (PageError(page))
187 goto error;
188
189 buf = kmap_atomic(page);
190 memcpy(devname, buf, size);
191 kunmap_atomic(buf);
192 put_page(page);
193 page = NULL;
194 }
195
196 /* work out what options we want */
197 super = AFS_FS_S(mntpt->d_sb);
198 memcpy(options, "cell=", 5);
199 strcpy(options + 5, super->volume->cell->name);
200 if (super->volume->type == AFSVL_RWVOL || rwpath)
201 strcat(options, ",rwpath");
202
203 /* try and do the mount */
204 _debug("--- attempting mount %s -o %s ---", devname, options);
205 mnt = vfs_kern_mount(&afs_fs_type, 0, devname, options);
206 _debug("--- mount result %p ---", mnt);
207
208 free_page((unsigned long) devname);
209 free_page((unsigned long) options);
210 _leave(" = %p", mnt);
211 return mnt;
212
213error:
214 put_page(page);
215error_no_page:
216 free_page((unsigned long) options);
217error_no_options:
218 free_page((unsigned long) devname);
219error_no_devname:
220 _leave(" = %d", ret);
221 return ERR_PTR(ret);
222}
223
224/*
225 * handle an automount point
226 */
227struct vfsmount *afs_d_automount(struct path *path)
228{
229 struct vfsmount *newmnt;
230
231 _enter("{%pd}", path->dentry);
232
233 newmnt = afs_mntpt_do_automount(path->dentry);
234 if (IS_ERR(newmnt))
235 return newmnt;
236
237 mntget(newmnt); /* prevent immediate expiration */
238 mnt_set_expiry(newmnt, &afs_vfsmounts);
239 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
240 afs_mntpt_expiry_timeout * HZ);
241 _leave(" = %p", newmnt);
242 return newmnt;
243}
244
245/*
246 * handle mountpoint expiry timer going off
247 */
248static void afs_mntpt_expiry_timed_out(struct work_struct *work)
249{
250 _enter("");
251
252 if (!list_empty(&afs_vfsmounts)) {
253 mark_mounts_for_expiry(&afs_vfsmounts);
254 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
255 afs_mntpt_expiry_timeout * HZ);
256 }
257
258 _leave("");
259}
260
261/*
262 * kill the AFS mountpoint timer if it's still running
263 */
264void afs_mntpt_kill_timer(void)
265{
266 _enter("");
267
268 ASSERT(list_empty(&afs_vfsmounts));
269 cancel_delayed_work_sync(&afs_mntpt_expiry_timer);
270}