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1da177e4 LT |
1 | /* -*- linux-c -*- --------------------------------------------------------- * |
2 | * | |
3 | * linux/fs/devpts/inode.c | |
4 | * | |
5 | * Copyright 1998-2004 H. Peter Anvin -- All Rights Reserved | |
6 | * | |
7 | * This file is part of the Linux kernel and is made available under | |
8 | * the terms of the GNU General Public License, version 2, or at your | |
9 | * option, any later version, incorporated herein by reference. | |
10 | * | |
11 | * ------------------------------------------------------------------------- */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/fs.h> | |
16 | #include <linux/sched.h> | |
17 | #include <linux/namei.h> | |
18 | #include <linux/mount.h> | |
19 | #include <linux/tty.h> | |
20 | #include <linux/devpts_fs.h> | |
7a673c6b | 21 | #include <linux/parser.h> |
1da177e4 LT |
22 | |
23 | #define DEVPTS_SUPER_MAGIC 0x1cd1 | |
24 | ||
1da177e4 LT |
25 | static struct vfsmount *devpts_mnt; |
26 | static struct dentry *devpts_root; | |
27 | ||
28 | static struct { | |
29 | int setuid; | |
30 | int setgid; | |
31 | uid_t uid; | |
32 | gid_t gid; | |
33 | umode_t mode; | |
34 | } config = {.mode = 0600}; | |
35 | ||
7a673c6b DP |
36 | enum { |
37 | Opt_uid, Opt_gid, Opt_mode, | |
38 | Opt_err | |
39 | }; | |
40 | ||
41 | static match_table_t tokens = { | |
42 | {Opt_uid, "uid=%u"}, | |
43 | {Opt_gid, "gid=%u"}, | |
44 | {Opt_mode, "mode=%o"}, | |
45 | {Opt_err, NULL} | |
46 | }; | |
47 | ||
1da177e4 LT |
48 | static int devpts_remount(struct super_block *sb, int *flags, char *data) |
49 | { | |
7a673c6b DP |
50 | char *p; |
51 | ||
52 | config.setuid = 0; | |
53 | config.setgid = 0; | |
54 | config.uid = 0; | |
55 | config.gid = 0; | |
56 | config.mode = 0600; | |
57 | ||
58 | while ((p = strsep(&data, ",")) != NULL) { | |
59 | substring_t args[MAX_OPT_ARGS]; | |
60 | int token; | |
61 | int option; | |
62 | ||
63 | if (!*p) | |
1da177e4 | 64 | continue; |
7a673c6b DP |
65 | |
66 | token = match_token(p, tokens, args); | |
67 | switch (token) { | |
68 | case Opt_uid: | |
69 | if (match_int(&args[0], &option)) | |
70 | return -EINVAL; | |
71 | config.uid = option; | |
72 | config.setuid = 1; | |
73 | break; | |
74 | case Opt_gid: | |
75 | if (match_int(&args[0], &option)) | |
76 | return -EINVAL; | |
77 | config.gid = option; | |
78 | config.setgid = 1; | |
79 | break; | |
80 | case Opt_mode: | |
81 | if (match_octal(&args[0], &option)) | |
82 | return -EINVAL; | |
83 | config.mode = option & ~S_IFMT; | |
84 | break; | |
85 | default: | |
86 | printk(KERN_ERR "devpts: called with bogus options\n"); | |
1da177e4 LT |
87 | return -EINVAL; |
88 | } | |
89 | } | |
1da177e4 LT |
90 | |
91 | return 0; | |
92 | } | |
93 | ||
94 | static struct super_operations devpts_sops = { | |
95 | .statfs = simple_statfs, | |
96 | .remount_fs = devpts_remount, | |
97 | }; | |
98 | ||
99 | static int | |
100 | devpts_fill_super(struct super_block *s, void *data, int silent) | |
101 | { | |
102 | struct inode * inode; | |
103 | ||
104 | s->s_blocksize = 1024; | |
105 | s->s_blocksize_bits = 10; | |
106 | s->s_magic = DEVPTS_SUPER_MAGIC; | |
107 | s->s_op = &devpts_sops; | |
1da177e4 LT |
108 | s->s_time_gran = 1; |
109 | ||
110 | inode = new_inode(s); | |
111 | if (!inode) | |
112 | goto fail; | |
113 | inode->i_ino = 1; | |
114 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
115 | inode->i_blocks = 0; | |
1da177e4 LT |
116 | inode->i_uid = inode->i_gid = 0; |
117 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; | |
118 | inode->i_op = &simple_dir_inode_operations; | |
119 | inode->i_fop = &simple_dir_operations; | |
120 | inode->i_nlink = 2; | |
121 | ||
122 | devpts_root = s->s_root = d_alloc_root(inode); | |
123 | if (s->s_root) | |
124 | return 0; | |
125 | ||
126 | printk("devpts: get root dentry failed\n"); | |
127 | iput(inode); | |
128 | fail: | |
129 | return -ENOMEM; | |
130 | } | |
131 | ||
454e2398 DH |
132 | static int devpts_get_sb(struct file_system_type *fs_type, |
133 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 134 | { |
454e2398 | 135 | return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt); |
1da177e4 LT |
136 | } |
137 | ||
138 | static struct file_system_type devpts_fs_type = { | |
139 | .owner = THIS_MODULE, | |
140 | .name = "devpts", | |
141 | .get_sb = devpts_get_sb, | |
142 | .kill_sb = kill_anon_super, | |
143 | }; | |
144 | ||
145 | /* | |
146 | * The normal naming convention is simply /dev/pts/<number>; this conforms | |
147 | * to the System V naming convention | |
148 | */ | |
149 | ||
150 | static struct dentry *get_node(int num) | |
151 | { | |
152 | char s[12]; | |
153 | struct dentry *root = devpts_root; | |
1b1dcc1b | 154 | mutex_lock(&root->d_inode->i_mutex); |
1da177e4 LT |
155 | return lookup_one_len(s, root, sprintf(s, "%d", num)); |
156 | } | |
157 | ||
158 | int devpts_pty_new(struct tty_struct *tty) | |
159 | { | |
160 | int number = tty->index; | |
161 | struct tty_driver *driver = tty->driver; | |
162 | dev_t device = MKDEV(driver->major, driver->minor_start+number); | |
163 | struct dentry *dentry; | |
164 | struct inode *inode = new_inode(devpts_mnt->mnt_sb); | |
165 | ||
166 | /* We're supposed to be given the slave end of a pty */ | |
167 | BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY); | |
168 | BUG_ON(driver->subtype != PTY_TYPE_SLAVE); | |
169 | ||
170 | if (!inode) | |
171 | return -ENOMEM; | |
172 | ||
173 | inode->i_ino = number+2; | |
1da177e4 LT |
174 | inode->i_uid = config.setuid ? config.uid : current->fsuid; |
175 | inode->i_gid = config.setgid ? config.gid : current->fsgid; | |
176 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | |
177 | init_special_inode(inode, S_IFCHR|config.mode, device); | |
8e18e294 | 178 | inode->i_private = tty; |
1da177e4 LT |
179 | |
180 | dentry = get_node(number); | |
181 | if (!IS_ERR(dentry) && !dentry->d_inode) | |
182 | d_instantiate(dentry, inode); | |
183 | ||
1b1dcc1b | 184 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
185 | |
186 | return 0; | |
187 | } | |
188 | ||
189 | struct tty_struct *devpts_get_tty(int number) | |
190 | { | |
191 | struct dentry *dentry = get_node(number); | |
192 | struct tty_struct *tty; | |
193 | ||
194 | tty = NULL; | |
195 | if (!IS_ERR(dentry)) { | |
196 | if (dentry->d_inode) | |
8e18e294 | 197 | tty = dentry->d_inode->i_private; |
1da177e4 LT |
198 | dput(dentry); |
199 | } | |
200 | ||
1b1dcc1b | 201 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
202 | |
203 | return tty; | |
204 | } | |
205 | ||
206 | void devpts_pty_kill(int number) | |
207 | { | |
208 | struct dentry *dentry = get_node(number); | |
209 | ||
210 | if (!IS_ERR(dentry)) { | |
211 | struct inode *inode = dentry->d_inode; | |
212 | if (inode) { | |
213 | inode->i_nlink--; | |
214 | d_delete(dentry); | |
215 | dput(dentry); | |
216 | } | |
217 | dput(dentry); | |
218 | } | |
1b1dcc1b | 219 | mutex_unlock(&devpts_root->d_inode->i_mutex); |
1da177e4 LT |
220 | } |
221 | ||
222 | static int __init init_devpts_fs(void) | |
223 | { | |
224 | int err = register_filesystem(&devpts_fs_type); | |
225 | if (!err) { | |
226 | devpts_mnt = kern_mount(&devpts_fs_type); | |
227 | if (IS_ERR(devpts_mnt)) | |
228 | err = PTR_ERR(devpts_mnt); | |
229 | } | |
230 | return err; | |
231 | } | |
232 | ||
233 | static void __exit exit_devpts_fs(void) | |
234 | { | |
235 | unregister_filesystem(&devpts_fs_type); | |
236 | mntput(devpts_mnt); | |
237 | } | |
238 | ||
239 | module_init(init_devpts_fs) | |
240 | module_exit(exit_devpts_fs) | |
241 | MODULE_LICENSE("GPL"); |