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 | |
20 | static struct dentry *afs_mntpt_lookup(struct inode *dir, |
21 | struct dentry *dentry, |
22 | unsigned int flags); |
23 | static int afs_mntpt_open(struct inode *inode, struct file *file); |
24 | static void afs_mntpt_expiry_timed_out(struct work_struct *work); |
25 | |
26 | const struct file_operations afs_mntpt_file_operations = { |
27 | .open = afs_mntpt_open, |
28 | .llseek = noop_llseek, |
29 | }; |
30 | |
31 | const struct inode_operations afs_mntpt_inode_operations = { |
32 | .lookup = afs_mntpt_lookup, |
33 | .readlink = page_readlink, |
34 | .getattr = afs_getattr, |
35 | }; |
36 | |
37 | const struct inode_operations afs_autocell_inode_operations = { |
38 | .getattr = afs_getattr, |
39 | }; |
40 | |
41 | static LIST_HEAD(afs_vfsmounts); |
42 | static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); |
43 | |
44 | static unsigned long afs_mntpt_expiry_timeout = 10 * 60; |
45 | |
46 | static const char afs_root_volume[] = "root.cell" ; |
47 | |
48 | /* |
49 | * no valid lookup procedure on this sort of dir |
50 | */ |
51 | static 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(error: -EREMOTE); |
57 | } |
58 | |
59 | /* |
60 | * no valid open procedure on this sort of dir |
61 | */ |
62 | static 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 | */ |
71 | static 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(sb: mntpt->d_sb); |
75 | struct afs_vnode *vnode = AFS_FS_I(inode: d_inode(dentry: 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(net: fc->net_ns); |
82 | fc->net_ns = get_net(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(ptr: cell)) { |
112 | pr_err("kAFS: unable to lookup cell '%pd'\n" , mntpt); |
113 | return PTR_ERR(ptr: 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(inode: d_inode(dentry: 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(mapping: d_inode(dentry: mntpt)->i_mapping, index: 0, NULL); |
132 | if (IS_ERR(ptr: page)) |
133 | return PTR_ERR(ptr: page); |
134 | |
135 | buf = kmap(page); |
136 | ret = -EINVAL; |
137 | if (buf[size - 1] == '.') |
138 | ret = vfs_parse_fs_string(fc, key: "source" , value: buf, v_size: 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 | */ |
151 | static 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(fs_type: &afs_fs_type, reference: mntpt); |
160 | if (IS_ERR(ptr: fc)) |
161 | return ERR_CAST(ptr: fc); |
162 | |
163 | ret = afs_mntpt_set_params(fc, mntpt); |
164 | if (!ret) |
165 | mnt = fc_mount(fc); |
166 | else |
167 | mnt = ERR_PTR(error: ret); |
168 | |
169 | put_fs_context(fc); |
170 | return mnt; |
171 | } |
172 | |
173 | /* |
174 | * handle an automount point |
175 | */ |
176 | struct 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(mntpt: path->dentry); |
183 | if (IS_ERR(ptr: newmnt)) |
184 | return newmnt; |
185 | |
186 | mntget(mnt: newmnt); /* prevent immediate expiration */ |
187 | mnt_set_expiry(mnt: newmnt, expiry_list: &afs_vfsmounts); |
188 | queue_delayed_work(wq: afs_wq, dwork: &afs_mntpt_expiry_timer, |
189 | delay: afs_mntpt_expiry_timeout * HZ); |
190 | _leave(" = %p" , newmnt); |
191 | return newmnt; |
192 | } |
193 | |
194 | /* |
195 | * handle mountpoint expiry timer going off |
196 | */ |
197 | static void afs_mntpt_expiry_timed_out(struct work_struct *work) |
198 | { |
199 | _enter("" ); |
200 | |
201 | if (!list_empty(head: &afs_vfsmounts)) { |
202 | mark_mounts_for_expiry(mounts: &afs_vfsmounts); |
203 | queue_delayed_work(wq: afs_wq, dwork: &afs_mntpt_expiry_timer, |
204 | delay: afs_mntpt_expiry_timeout * HZ); |
205 | } |
206 | |
207 | _leave("" ); |
208 | } |
209 | |
210 | /* |
211 | * kill the AFS mountpoint timer if it's still running |
212 | */ |
213 | void afs_mntpt_kill_timer(void) |
214 | { |
215 | _enter("" ); |
216 | |
217 | ASSERT(list_empty(&afs_vfsmounts)); |
218 | cancel_delayed_work_sync(dwork: &afs_mntpt_expiry_timer); |
219 | } |
220 | |