blob: 2f27e578d4660e89c1215d7a9edc2dffa6439c89 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- 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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090018#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/mount.h>
20#include <linux/tty.h>
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070021#include <linux/mutex.h>
Nick Black1fd7317d2009-09-22 16:43:33 -070022#include <linux/magic.h>
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070023#include <linux/idr.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/devpts_fs.h>
Domen Puncer7a673c62006-03-23 03:00:59 -080025#include <linux/parser.h>
Florin Malita3972b7f2007-05-08 00:24:18 -070026#include <linux/fsnotify.h>
Miklos Szeredib87a2672008-02-08 04:21:41 -080027#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Miklos Szeredib87a2672008-02-08 04:21:41 -080029#define DEVPTS_DEFAULT_MODE 0600
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +000030/*
31 * ptmx is a new node in /dev/pts and will be unused in legacy (single-
32 * instance) mode. To prevent surprises in user space, set permissions of
33 * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful
34 * permissions.
35 */
36#define DEVPTS_DEFAULT_PTMX_MODE 0000
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +010037#define PTMX_MINOR 2
Miklos Szeredib87a2672008-02-08 04:21:41 -080038
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070039extern int pty_limit; /* Config limit on Unix98 ptys */
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070040static DEFINE_MUTEX(allocated_ptys_lock);
41
Linus Torvalds1da177e2005-04-16 15:20:36 -070042static struct vfsmount *devpts_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +000044struct pts_mount_opts {
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 int setuid;
46 int setgid;
47 uid_t uid;
48 gid_t gid;
49 umode_t mode;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +000050 umode_t ptmxmode;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +000051 int newinstance;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +000052};
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
Domen Puncer7a673c62006-03-23 03:00:59 -080054enum {
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +000055 Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance,
Domen Puncer7a673c62006-03-23 03:00:59 -080056 Opt_err
57};
58
Steven Whitehousea447c092008-10-13 10:46:57 +010059static const match_table_t tokens = {
Domen Puncer7a673c62006-03-23 03:00:59 -080060 {Opt_uid, "uid=%u"},
61 {Opt_gid, "gid=%u"},
62 {Opt_mode, "mode=%o"},
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +000063#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
64 {Opt_ptmxmode, "ptmxmode=%o"},
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +000065 {Opt_newinstance, "newinstance"},
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +000066#endif
Domen Puncer7a673c62006-03-23 03:00:59 -080067 {Opt_err, NULL}
68};
69
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +000070struct pts_fs_info {
71 struct ida allocated_ptys;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +000072 struct pts_mount_opts mount_opts;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +000073 struct dentry *ptmx_dentry;
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +000074};
75
76static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
77{
78 return sb->s_fs_info;
79}
80
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +000081static inline struct super_block *pts_sb_from_inode(struct inode *inode)
82{
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +000083#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +000084 if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
85 return inode->i_sb;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +000086#endif
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +000087 return devpts_mnt->mnt_sb;
88}
89
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +000090#define PARSE_MOUNT 0
91#define PARSE_REMOUNT 1
92
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -070093/*
94 * parse_mount_options():
95 * Set @opts to mount options specified in @data. If an option is not
96 * specified in @data, set it to its default value. The exception is
97 * 'newinstance' option which can only be set/cleared on a mount (i.e.
98 * cannot be changed during remount).
99 *
100 * Note: @data may be NULL (in which case all options are set to default).
101 */
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000102static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103{
Domen Puncer7a673c62006-03-23 03:00:59 -0800104 char *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000106 opts->setuid = 0;
107 opts->setgid = 0;
108 opts->uid = 0;
109 opts->gid = 0;
110 opts->mode = DEVPTS_DEFAULT_MODE;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000111 opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
Domen Puncer7a673c62006-03-23 03:00:59 -0800112
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000113 /* newinstance makes sense only on initial mount */
114 if (op == PARSE_MOUNT)
115 opts->newinstance = 0;
116
Domen Puncer7a673c62006-03-23 03:00:59 -0800117 while ((p = strsep(&data, ",")) != NULL) {
118 substring_t args[MAX_OPT_ARGS];
119 int token;
120 int option;
121
122 if (!*p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 continue;
Domen Puncer7a673c62006-03-23 03:00:59 -0800124
125 token = match_token(p, tokens, args);
126 switch (token) {
127 case Opt_uid:
128 if (match_int(&args[0], &option))
129 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000130 opts->uid = option;
131 opts->setuid = 1;
Domen Puncer7a673c62006-03-23 03:00:59 -0800132 break;
133 case Opt_gid:
134 if (match_int(&args[0], &option))
135 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000136 opts->gid = option;
137 opts->setgid = 1;
Domen Puncer7a673c62006-03-23 03:00:59 -0800138 break;
139 case Opt_mode:
140 if (match_octal(&args[0], &option))
141 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000142 opts->mode = option & S_IALLUGO;
Domen Puncer7a673c62006-03-23 03:00:59 -0800143 break;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000144#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
145 case Opt_ptmxmode:
146 if (match_octal(&args[0], &option))
147 return -EINVAL;
148 opts->ptmxmode = option & S_IALLUGO;
149 break;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000150 case Opt_newinstance:
151 /* newinstance makes sense only on initial mount */
152 if (op == PARSE_MOUNT)
153 opts->newinstance = 1;
154 break;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000155#endif
Domen Puncer7a673c62006-03-23 03:00:59 -0800156 default:
157 printk(KERN_ERR "devpts: called with bogus options\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 return -EINVAL;
159 }
160 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
162 return 0;
163}
164
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000165#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
166static int mknod_ptmx(struct super_block *sb)
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000167{
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000168 int mode;
169 int rc = -ENOMEM;
170 struct dentry *dentry;
171 struct inode *inode;
172 struct dentry *root = sb->s_root;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000173 struct pts_fs_info *fsi = DEVPTS_SB(sb);
174 struct pts_mount_opts *opts = &fsi->mount_opts;
175
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000176 mutex_lock(&root->d_inode->i_mutex);
177
178 /* If we have already created ptmx node, return */
179 if (fsi->ptmx_dentry) {
180 rc = 0;
181 goto out;
182 }
183
184 dentry = d_alloc_name(root, "ptmx");
185 if (!dentry) {
186 printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n");
187 goto out;
188 }
189
190 /*
191 * Create a new 'ptmx' node in this mount of devpts.
192 */
193 inode = new_inode(sb);
194 if (!inode) {
195 printk(KERN_ERR "Unable to alloc inode for ptmx node\n");
196 dput(dentry);
197 goto out;
198 }
199
200 inode->i_ino = 2;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000201 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
202
203 mode = S_IFCHR|opts->ptmxmode;
204 init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
205
206 d_add(dentry, inode);
207
208 fsi->ptmx_dentry = dentry;
209 rc = 0;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000210out:
211 mutex_unlock(&root->d_inode->i_mutex);
212 return rc;
213}
214
215static void update_ptmx_mode(struct pts_fs_info *fsi)
216{
217 struct inode *inode;
218 if (fsi->ptmx_dentry) {
219 inode = fsi->ptmx_dentry->d_inode;
220 inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;
221 }
222}
223#else
224static inline void update_ptmx_mode(struct pts_fs_info *fsi)
225{
226 return;
227}
228#endif
229
230static int devpts_remount(struct super_block *sb, int *flags, char *data)
231{
232 int err;
233 struct pts_fs_info *fsi = DEVPTS_SB(sb);
234 struct pts_mount_opts *opts = &fsi->mount_opts;
235
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000236 err = parse_mount_options(data, PARSE_REMOUNT, opts);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000237
238 /*
239 * parse_mount_options() restores options to default values
240 * before parsing and may have changed ptmxmode. So, update the
241 * mode in the inode too. Bogus options don't fail the remount,
242 * so do this even on error return.
243 */
244 update_ptmx_mode(fsi);
245
246 return err;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000247}
248
Miklos Szeredib87a2672008-02-08 04:21:41 -0800249static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
250{
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000251 struct pts_fs_info *fsi = DEVPTS_SB(vfs->mnt_sb);
252 struct pts_mount_opts *opts = &fsi->mount_opts;
253
254 if (opts->setuid)
255 seq_printf(seq, ",uid=%u", opts->uid);
256 if (opts->setgid)
257 seq_printf(seq, ",gid=%u", opts->gid);
258 seq_printf(seq, ",mode=%03o", opts->mode);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000259#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
260 seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
261#endif
Miklos Szeredib87a2672008-02-08 04:21:41 -0800262
263 return 0;
264}
265
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800266static const struct super_operations devpts_sops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 .statfs = simple_statfs,
268 .remount_fs = devpts_remount,
Miklos Szeredib87a2672008-02-08 04:21:41 -0800269 .show_options = devpts_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270};
271
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000272static void *new_pts_fs_info(void)
273{
274 struct pts_fs_info *fsi;
275
276 fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
277 if (!fsi)
278 return NULL;
279
280 ida_init(&fsi->allocated_ptys);
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000281 fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000282 fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000283
284 return fsi;
285}
286
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287static int
288devpts_fill_super(struct super_block *s, void *data, int silent)
289{
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000290 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
292 s->s_blocksize = 1024;
293 s->s_blocksize_bits = 10;
294 s->s_magic = DEVPTS_SUPER_MAGIC;
295 s->s_op = &devpts_sops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 s->s_time_gran = 1;
297
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000298 s->s_fs_info = new_pts_fs_info();
299 if (!s->s_fs_info)
300 goto fail;
301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 inode = new_inode(s);
303 if (!inode)
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000304 goto free_fsi;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 inode->i_ino = 1;
306 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
308 inode->i_op = &simple_dir_inode_operations;
309 inode->i_fop = &simple_dir_operations;
310 inode->i_nlink = 2;
311
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000312 s->s_root = d_alloc_root(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 if (s->s_root)
314 return 0;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000315
Alan Cox835aa442009-01-02 13:42:48 +0000316 printk(KERN_ERR "devpts: get root dentry failed\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 iput(inode);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000318
319free_fsi:
320 kfree(s->s_fs_info);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321fail:
322 return -ENOMEM;
323}
324
Andrew Morton8c056e52009-01-02 13:44:12 +0000325#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000326static int compare_init_pts_sb(struct super_block *s, void *p)
327{
328 if (devpts_mnt)
329 return devpts_mnt->mnt_sb == s;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000330 return 0;
331}
332
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000333/*
Al Virofc14f2f2010-07-25 01:48:30 +0400334 * devpts_mount()
Sukadev Bhattiprolu289f00e2009-03-07 10:12:06 -0800335 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800336 * If the '-o newinstance' mount option was specified, mount a new
337 * (private) instance of devpts. PTYs created in this instance are
338 * independent of the PTYs in other devpts instances.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000339 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800340 * If the '-o newinstance' option was not specified, mount/remount the
341 * initial kernel mount of devpts. This type of mount gives the
342 * legacy, single-instance semantics.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000343 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800344 * The 'newinstance' option is needed to support multiple namespace
345 * semantics in devpts while preserving backward compatibility of the
346 * current 'single-namespace' semantics. i.e all mounts of devpts
347 * without the 'newinstance' mount option should bind to the initial
Al Virofc14f2f2010-07-25 01:48:30 +0400348 * kernel mount, like mount_single().
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000349 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800350 * Mounts with 'newinstance' option create a new, private namespace.
351 *
352 * NOTE:
353 *
Al Virofc14f2f2010-07-25 01:48:30 +0400354 * For single-mount semantics, devpts cannot use mount_single(),
355 * because mount_single()/sget() find and use the super-block from
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000356 * the most recent mount of devpts. But that recent mount may be a
Al Virofc14f2f2010-07-25 01:48:30 +0400357 * 'newinstance' mount and mount_single() would pick the newinstance
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000358 * super-block instead of the initial super-block.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000359 */
Al Virofc14f2f2010-07-25 01:48:30 +0400360static struct dentry *devpts_mount(struct file_system_type *fs_type,
361 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362{
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800363 int error;
364 struct pts_mount_opts opts;
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800365 struct super_block *s;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000366
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -0700367 error = parse_mount_options(data, PARSE_MOUNT, &opts);
368 if (error)
Al Virofc14f2f2010-07-25 01:48:30 +0400369 return ERR_PTR(error);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000370
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800371 if (opts.newinstance)
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800372 s = sget(fs_type, NULL, set_anon_super, NULL);
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800373 else
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800374 s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800375
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800376 if (IS_ERR(s))
Al Virofc14f2f2010-07-25 01:48:30 +0400377 return ERR_CAST(s);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800378
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800379 if (!s->s_root) {
380 s->s_flags = flags;
381 error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
382 if (error)
383 goto out_undo_sget;
384 s->s_flags |= MS_ACTIVE;
385 }
386
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800387 memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
388
389 error = mknod_ptmx(s);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800390 if (error)
Al Viro89468072010-03-20 21:57:43 -0400391 goto out_undo_sget;
392
Al Virofc14f2f2010-07-25 01:48:30 +0400393 return dget(s->s_root);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800394
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800395out_undo_sget:
Al Viro6f5bbff2009-05-06 01:34:22 -0400396 deactivate_locked_super(s);
Al Virofc14f2f2010-07-25 01:48:30 +0400397 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398}
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800399
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000400#else
401/*
402 * This supports only the legacy single-instance semantics (no
403 * multiple-instance semantics)
404 */
Al Virofc14f2f2010-07-25 01:48:30 +0400405static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags,
406 const char *dev_name, void *data)
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000407{
Al Virofc14f2f2010-07-25 01:48:30 +0400408 return mount_single(fs_type, flags, data, devpts_fill_super);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000409}
410#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000412static void devpts_kill_sb(struct super_block *sb)
413{
414 struct pts_fs_info *fsi = DEVPTS_SB(sb);
415
416 kfree(fsi);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000417 kill_litter_super(sb);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000418}
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420static struct file_system_type devpts_fs_type = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 .name = "devpts",
Al Virofc14f2f2010-07-25 01:48:30 +0400422 .mount = devpts_mount,
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000423 .kill_sb = devpts_kill_sb,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424};
425
426/*
427 * The normal naming convention is simply /dev/pts/<number>; this conforms
428 * to the System V naming convention
429 */
430
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100431int devpts_new_index(struct inode *ptmx_inode)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700432{
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000433 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
434 struct pts_fs_info *fsi = DEVPTS_SB(sb);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700435 int index;
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400436 int ida_ret;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700437
438retry:
Alan Cox835aa442009-01-02 13:42:48 +0000439 if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700440 return -ENOMEM;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700441
442 mutex_lock(&allocated_ptys_lock);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000443 ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400444 if (ida_ret < 0) {
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700445 mutex_unlock(&allocated_ptys_lock);
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400446 if (ida_ret == -EAGAIN)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700447 goto retry;
448 return -EIO;
449 }
450
451 if (index >= pty_limit) {
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000452 ida_remove(&fsi->allocated_ptys, index);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700453 mutex_unlock(&allocated_ptys_lock);
454 return -EIO;
455 }
456 mutex_unlock(&allocated_ptys_lock);
457 return index;
458}
459
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100460void devpts_kill_index(struct inode *ptmx_inode, int idx)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700461{
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000462 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
463 struct pts_fs_info *fsi = DEVPTS_SB(sb);
464
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700465 mutex_lock(&allocated_ptys_lock);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000466 ida_remove(&fsi->allocated_ptys, idx);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700467 mutex_unlock(&allocated_ptys_lock);
468}
469
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100470int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471{
Alan Cox835aa442009-01-02 13:42:48 +0000472 /* tty layer puts index from devpts_new_index() in here */
473 int number = tty->index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 struct tty_driver *driver = tty->driver;
475 dev_t device = MKDEV(driver->major, driver->minor_start+number);
476 struct dentry *dentry;
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000477 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
478 struct inode *inode = new_inode(sb);
479 struct dentry *root = sb->s_root;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000480 struct pts_fs_info *fsi = DEVPTS_SB(sb);
481 struct pts_mount_opts *opts = &fsi->mount_opts;
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300482 int ret = 0;
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100483 char s[12];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484
485 /* We're supposed to be given the slave end of a pty */
486 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
487 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
488
489 if (!inode)
490 return -ENOMEM;
491
David Howellsd0eafc72009-01-02 13:44:49 +0000492 inode->i_ino = number + 3;
493 inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
494 inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000496 init_special_inode(inode, S_IFCHR|opts->mode, device);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700497 inode->i_private = tty;
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100498 tty->driver_data = inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100500 sprintf(s, "%d", number);
501
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000502 mutex_lock(&root->d_inode->i_mutex);
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100503
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000504 dentry = d_alloc_name(root, s);
Andrey Vaginb12d1252011-03-22 16:35:11 -0700505 if (dentry) {
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100506 d_add(dentry, inode);
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000507 fsnotify_create(root->d_inode, dentry);
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300508 } else {
509 iput(inode);
510 ret = -ENOMEM;
Florin Malita3972b7f2007-05-08 00:24:18 -0700511 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000513 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300515 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516}
517
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100518struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519{
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800520 struct dentry *dentry;
521 struct tty_struct *tty;
522
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +0100523 BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800525 /* Ensure dentry has not been deleted by devpts_pty_kill() */
526 dentry = d_find_alias(pts_inode);
527 if (!dentry)
528 return NULL;
529
530 tty = NULL;
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +0100531 if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800532 tty = (struct tty_struct *)pts_inode->i_private;
533
534 dput(dentry);
535
536 return tty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537}
538
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100539void devpts_pty_kill(struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540{
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100541 struct inode *inode = tty->driver_data;
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000542 struct super_block *sb = pts_sb_from_inode(inode);
543 struct dentry *root = sb->s_root;
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100544 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100546 BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
547
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000548 mutex_lock(&root->d_inode->i_mutex);
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100549
550 dentry = d_find_alias(inode);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000551
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300552 inode->i_nlink--;
553 d_delete(dentry);
554 dput(dentry); /* d_alloc_name() in devpts_pty_new() */
Alan Cox835aa442009-01-02 13:42:48 +0000555 dput(dentry); /* d_find_alias above */
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300556
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000557 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558}
559
560static int __init init_devpts_fs(void)
561{
562 int err = register_filesystem(&devpts_fs_type);
563 if (!err) {
564 devpts_mnt = kern_mount(&devpts_fs_type);
Alan Cox93d55812009-06-11 14:03:55 +0100565 if (IS_ERR(devpts_mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 err = PTR_ERR(devpts_mnt);
Alan Cox93d55812009-06-11 14:03:55 +0100567 unregister_filesystem(&devpts_fs_type);
568 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 }
570 return err;
571}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572module_init(init_devpts_fs)