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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/mutex.h>
21#include <linux/idr.h>
22#include <linux/devpts_fs.h>
23#include <linux/parser.h>
24#include <linux/fsnotify.h>
25#include <linux/seq_file.h>
26
27#define DEVPTS_SUPER_MAGIC 0x1cd1
28
29#define DEVPTS_DEFAULT_MODE 0600
30#define PTMX_MINOR 2
31
32extern int pty_limit;
33static DEFINE_IDA(allocated_ptys);
34static DEFINE_MUTEX(allocated_ptys_lock);
35
36static struct vfsmount *devpts_mnt;
37static struct dentry *devpts_root;
38
39static struct {
40 int setuid;
41 int setgid;
42 uid_t uid;
43 gid_t gid;
44 umode_t mode;
45} config = {.mode = DEVPTS_DEFAULT_MODE};
46
47enum {
48 Opt_uid, Opt_gid, Opt_mode,
49 Opt_err
50};
51
52static const match_table_t tokens = {
53 {Opt_uid, "uid=%u"},
54 {Opt_gid, "gid=%u"},
55 {Opt_mode, "mode=%o"},
56 {Opt_err, NULL}
57};
58
59static int devpts_remount(struct super_block *sb, int *flags, char *data)
60{
61 char *p;
62
63 config.setuid = 0;
64 config.setgid = 0;
65 config.uid = 0;
66 config.gid = 0;
67 config.mode = DEVPTS_DEFAULT_MODE;
68
69 while ((p = strsep(&data, ",")) != NULL) {
70 substring_t args[MAX_OPT_ARGS];
71 int token;
72 int option;
73
74 if (!*p)
75 continue;
76
77 token = match_token(p, tokens, args);
78 switch (token) {
79 case Opt_uid:
80 if (match_int(&args[0], &option))
81 return -EINVAL;
82 config.uid = option;
83 config.setuid = 1;
84 break;
85 case Opt_gid:
86 if (match_int(&args[0], &option))
87 return -EINVAL;
88 config.gid = option;
89 config.setgid = 1;
90 break;
91 case Opt_mode:
92 if (match_octal(&args[0], &option))
93 return -EINVAL;
94 config.mode = option & S_IALLUGO;
95 break;
96 default:
97 printk(KERN_ERR "devpts: called with bogus options\n");
98 return -EINVAL;
99 }
100 }
101
102 return 0;
103}
104
105static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
106{
107 if (config.setuid)
108 seq_printf(seq, ",uid=%u", config.uid);
109 if (config.setgid)
110 seq_printf(seq, ",gid=%u", config.gid);
111 seq_printf(seq, ",mode=%03o", config.mode);
112
113 return 0;
114}
115
116static const struct super_operations devpts_sops = {
117 .statfs = simple_statfs,
118 .remount_fs = devpts_remount,
119 .show_options = devpts_show_options,
120};
121
122static int
123devpts_fill_super(struct super_block *s, void *data, int silent)
124{
125 struct inode * inode;
126
127 s->s_blocksize = 1024;
128 s->s_blocksize_bits = 10;
129 s->s_magic = DEVPTS_SUPER_MAGIC;
130 s->s_op = &devpts_sops;
131 s->s_time_gran = 1;
132
133 inode = new_inode(s);
134 if (!inode)
135 goto fail;
136 inode->i_ino = 1;
137 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
138 inode->i_blocks = 0;
139 inode->i_uid = inode->i_gid = 0;
140 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
141 inode->i_op = &simple_dir_inode_operations;
142 inode->i_fop = &simple_dir_operations;
143 inode->i_nlink = 2;
144
145 devpts_root = s->s_root = d_alloc_root(inode);
146 if (s->s_root)
147 return 0;
148
149 printk("devpts: get root dentry failed\n");
150 iput(inode);
151fail:
152 return -ENOMEM;
153}
154
155static int devpts_get_sb(struct file_system_type *fs_type,
156 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
157{
158 return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
159}
160
161static struct file_system_type devpts_fs_type = {
162 .owner = THIS_MODULE,
163 .name = "devpts",
164 .get_sb = devpts_get_sb,
165 .kill_sb = kill_anon_super,
166};
167
168
169
170
171
172
173int devpts_new_index(struct inode *ptmx_inode)
174{
175 int index;
176 int ida_ret;
177
178retry:
179 if (!ida_pre_get(&allocated_ptys, GFP_KERNEL)) {
180 return -ENOMEM;
181 }
182
183 mutex_lock(&allocated_ptys_lock);
184 ida_ret = ida_get_new(&allocated_ptys, &index);
185 if (ida_ret < 0) {
186 mutex_unlock(&allocated_ptys_lock);
187 if (ida_ret == -EAGAIN)
188 goto retry;
189 return -EIO;
190 }
191
192 if (index >= pty_limit) {
193 ida_remove(&allocated_ptys, index);
194 mutex_unlock(&allocated_ptys_lock);
195 return -EIO;
196 }
197 mutex_unlock(&allocated_ptys_lock);
198 return index;
199}
200
201void devpts_kill_index(struct inode *ptmx_inode, int idx)
202{
203 mutex_lock(&allocated_ptys_lock);
204 ida_remove(&allocated_ptys, idx);
205 mutex_unlock(&allocated_ptys_lock);
206}
207
208int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
209{
210 int number = tty->index;
211 struct tty_driver *driver = tty->driver;
212 dev_t device = MKDEV(driver->major, driver->minor_start+number);
213 struct dentry *dentry;
214 struct inode *inode = new_inode(devpts_mnt->mnt_sb);
215 char s[12];
216
217
218 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
219 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
220
221 if (!inode)
222 return -ENOMEM;
223
224 inode->i_ino = number+2;
225 inode->i_uid = config.setuid ? config.uid : current->fsuid;
226 inode->i_gid = config.setgid ? config.gid : current->fsgid;
227 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
228 init_special_inode(inode, S_IFCHR|config.mode, device);
229 inode->i_private = tty;
230 tty->driver_data = inode;
231
232 sprintf(s, "%d", number);
233
234 mutex_lock(&devpts_root->d_inode->i_mutex);
235
236 dentry = d_alloc_name(devpts_root, s);
237 if (!IS_ERR(dentry)) {
238 d_add(dentry, inode);
239 fsnotify_create(devpts_root->d_inode, dentry);
240 }
241
242 mutex_unlock(&devpts_root->d_inode->i_mutex);
243
244 return 0;
245}
246
247struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
248{
249 BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
250
251 if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
252 return (struct tty_struct *)pts_inode->i_private;
253 return NULL;
254}
255
256void devpts_pty_kill(struct tty_struct *tty)
257{
258 struct inode *inode = tty->driver_data;
259 struct dentry *dentry;
260
261 BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
262
263 mutex_lock(&devpts_root->d_inode->i_mutex);
264
265 dentry = d_find_alias(inode);
266 if (dentry && !IS_ERR(dentry)) {
267 inode->i_nlink--;
268 d_delete(dentry);
269 dput(dentry);
270 }
271
272 mutex_unlock(&devpts_root->d_inode->i_mutex);
273}
274
275static int __init init_devpts_fs(void)
276{
277 int err = register_filesystem(&devpts_fs_type);
278 if (!err) {
279 devpts_mnt = kern_mount(&devpts_fs_type);
280 if (IS_ERR(devpts_mnt))
281 err = PTR_ERR(devpts_mnt);
282 }
283 return err;
284}
285
286static void __exit exit_devpts_fs(void)
287{
288 unregister_filesystem(&devpts_fs_type);
289 mntput(devpts_mnt);
290}
291
292module_init(init_devpts_fs)
293module_exit(exit_devpts_fs)
294MODULE_LICENSE("GPL");
295
