blob: 10f5e0b484dbabefb7f5e252b2cd2626ffe5a308 [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 Black1fd73172009-09-22 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
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040039/*
40 * sysctl support for setting limits on the number of Unix98 ptys allocated.
41 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
42 */
43static int pty_limit = NR_UNIX98_PTY_DEFAULT;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +040044static int pty_reserve = NR_UNIX98_PTY_RESERVE;
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040045static int pty_limit_min;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +040046static int pty_limit_max = INT_MAX;
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040047static int pty_count;
48
49static struct ctl_table pty_table[] = {
50 {
51 .procname = "max",
52 .maxlen = sizeof(int),
53 .mode = 0644,
54 .data = &pty_limit,
55 .proc_handler = proc_dointvec_minmax,
56 .extra1 = &pty_limit_min,
57 .extra2 = &pty_limit_max,
58 }, {
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +040059 .procname = "reserve",
60 .maxlen = sizeof(int),
61 .mode = 0644,
62 .data = &pty_reserve,
63 .proc_handler = proc_dointvec_minmax,
64 .extra1 = &pty_limit_min,
65 .extra2 = &pty_limit_max,
66 }, {
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040067 .procname = "nr",
68 .maxlen = sizeof(int),
69 .mode = 0444,
70 .data = &pty_count,
71 .proc_handler = proc_dointvec,
72 },
73 {}
74};
75
76static struct ctl_table pty_kern_table[] = {
77 {
78 .procname = "pty",
79 .mode = 0555,
80 .child = pty_table,
81 },
82 {}
83};
84
85static struct ctl_table pty_root_table[] = {
86 {
87 .procname = "kernel",
88 .mode = 0555,
89 .child = pty_kern_table,
90 },
91 {}
92};
93
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070094static DEFINE_MUTEX(allocated_ptys_lock);
95
Linus Torvalds1da177e2005-04-16 15:20:36 -070096static struct vfsmount *devpts_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -070097
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +000098struct pts_mount_opts {
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 int setuid;
100 int setgid;
101 uid_t uid;
102 gid_t gid;
103 umode_t mode;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000104 umode_t ptmxmode;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000105 int newinstance;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400106 int max;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000107};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
Domen Puncer7a673c62006-03-23 03:00:59 -0800109enum {
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400110 Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max,
Domen Puncer7a673c62006-03-23 03:00:59 -0800111 Opt_err
112};
113
Steven Whitehousea447c092008-10-13 10:46:57 +0100114static const match_table_t tokens = {
Domen Puncer7a673c62006-03-23 03:00:59 -0800115 {Opt_uid, "uid=%u"},
116 {Opt_gid, "gid=%u"},
117 {Opt_mode, "mode=%o"},
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000118#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
119 {Opt_ptmxmode, "ptmxmode=%o"},
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000120 {Opt_newinstance, "newinstance"},
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400121 {Opt_max, "max=%d"},
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000122#endif
Domen Puncer7a673c62006-03-23 03:00:59 -0800123 {Opt_err, NULL}
124};
125
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000126struct pts_fs_info {
127 struct ida allocated_ptys;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000128 struct pts_mount_opts mount_opts;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000129 struct dentry *ptmx_dentry;
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000130};
131
132static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
133{
134 return sb->s_fs_info;
135}
136
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000137static inline struct super_block *pts_sb_from_inode(struct inode *inode)
138{
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000139#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000140 if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
141 return inode->i_sb;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000142#endif
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000143 return devpts_mnt->mnt_sb;
144}
145
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000146#define PARSE_MOUNT 0
147#define PARSE_REMOUNT 1
148
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -0700149/*
150 * parse_mount_options():
151 * Set @opts to mount options specified in @data. If an option is not
152 * specified in @data, set it to its default value. The exception is
153 * 'newinstance' option which can only be set/cleared on a mount (i.e.
154 * cannot be changed during remount).
155 *
156 * Note: @data may be NULL (in which case all options are set to default).
157 */
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000158static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159{
Domen Puncer7a673c62006-03-23 03:00:59 -0800160 char *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000162 opts->setuid = 0;
163 opts->setgid = 0;
164 opts->uid = 0;
165 opts->gid = 0;
166 opts->mode = DEVPTS_DEFAULT_MODE;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000167 opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400168 opts->max = NR_UNIX98_PTY_MAX;
Domen Puncer7a673c62006-03-23 03:00:59 -0800169
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000170 /* newinstance makes sense only on initial mount */
171 if (op == PARSE_MOUNT)
172 opts->newinstance = 0;
173
Domen Puncer7a673c62006-03-23 03:00:59 -0800174 while ((p = strsep(&data, ",")) != NULL) {
175 substring_t args[MAX_OPT_ARGS];
176 int token;
177 int option;
178
179 if (!*p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 continue;
Domen Puncer7a673c62006-03-23 03:00:59 -0800181
182 token = match_token(p, tokens, args);
183 switch (token) {
184 case Opt_uid:
185 if (match_int(&args[0], &option))
186 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000187 opts->uid = option;
188 opts->setuid = 1;
Domen Puncer7a673c62006-03-23 03:00:59 -0800189 break;
190 case Opt_gid:
191 if (match_int(&args[0], &option))
192 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000193 opts->gid = option;
194 opts->setgid = 1;
Domen Puncer7a673c62006-03-23 03:00:59 -0800195 break;
196 case Opt_mode:
197 if (match_octal(&args[0], &option))
198 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000199 opts->mode = option & S_IALLUGO;
Domen Puncer7a673c62006-03-23 03:00:59 -0800200 break;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000201#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
202 case Opt_ptmxmode:
203 if (match_octal(&args[0], &option))
204 return -EINVAL;
205 opts->ptmxmode = option & S_IALLUGO;
206 break;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000207 case Opt_newinstance:
208 /* newinstance makes sense only on initial mount */
209 if (op == PARSE_MOUNT)
210 opts->newinstance = 1;
211 break;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400212 case Opt_max:
213 if (match_int(&args[0], &option) ||
214 option < 0 || option > NR_UNIX98_PTY_MAX)
215 return -EINVAL;
216 opts->max = option;
217 break;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000218#endif
Domen Puncer7a673c62006-03-23 03:00:59 -0800219 default:
220 printk(KERN_ERR "devpts: called with bogus options\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 return -EINVAL;
222 }
223 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224
225 return 0;
226}
227
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000228#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
229static int mknod_ptmx(struct super_block *sb)
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000230{
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000231 int mode;
232 int rc = -ENOMEM;
233 struct dentry *dentry;
234 struct inode *inode;
235 struct dentry *root = sb->s_root;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000236 struct pts_fs_info *fsi = DEVPTS_SB(sb);
237 struct pts_mount_opts *opts = &fsi->mount_opts;
238
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000239 mutex_lock(&root->d_inode->i_mutex);
240
241 /* If we have already created ptmx node, return */
242 if (fsi->ptmx_dentry) {
243 rc = 0;
244 goto out;
245 }
246
247 dentry = d_alloc_name(root, "ptmx");
248 if (!dentry) {
249 printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n");
250 goto out;
251 }
252
253 /*
254 * Create a new 'ptmx' node in this mount of devpts.
255 */
256 inode = new_inode(sb);
257 if (!inode) {
258 printk(KERN_ERR "Unable to alloc inode for ptmx node\n");
259 dput(dentry);
260 goto out;
261 }
262
263 inode->i_ino = 2;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000264 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
265
266 mode = S_IFCHR|opts->ptmxmode;
267 init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
268
269 d_add(dentry, inode);
270
271 fsi->ptmx_dentry = dentry;
272 rc = 0;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000273out:
274 mutex_unlock(&root->d_inode->i_mutex);
275 return rc;
276}
277
278static void update_ptmx_mode(struct pts_fs_info *fsi)
279{
280 struct inode *inode;
281 if (fsi->ptmx_dentry) {
282 inode = fsi->ptmx_dentry->d_inode;
283 inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;
284 }
285}
286#else
287static inline void update_ptmx_mode(struct pts_fs_info *fsi)
288{
289 return;
290}
291#endif
292
293static int devpts_remount(struct super_block *sb, int *flags, char *data)
294{
295 int err;
296 struct pts_fs_info *fsi = DEVPTS_SB(sb);
297 struct pts_mount_opts *opts = &fsi->mount_opts;
298
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000299 err = parse_mount_options(data, PARSE_REMOUNT, opts);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000300
301 /*
302 * parse_mount_options() restores options to default values
303 * before parsing and may have changed ptmxmode. So, update the
304 * mode in the inode too. Bogus options don't fail the remount,
305 * so do this even on error return.
306 */
307 update_ptmx_mode(fsi);
308
309 return err;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000310}
311
Al Viro34c80b12011-12-08 21:32:45 -0500312static int devpts_show_options(struct seq_file *seq, struct dentry *root)
Miklos Szeredib87a2672008-02-08 04:21:41 -0800313{
Al Viro34c80b12011-12-08 21:32:45 -0500314 struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb);
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000315 struct pts_mount_opts *opts = &fsi->mount_opts;
316
317 if (opts->setuid)
318 seq_printf(seq, ",uid=%u", opts->uid);
319 if (opts->setgid)
320 seq_printf(seq, ",gid=%u", opts->gid);
321 seq_printf(seq, ",mode=%03o", opts->mode);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000322#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
323 seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400324 if (opts->max < NR_UNIX98_PTY_MAX)
325 seq_printf(seq, ",max=%d", opts->max);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000326#endif
Miklos Szeredib87a2672008-02-08 04:21:41 -0800327
328 return 0;
329}
330
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800331static const struct super_operations devpts_sops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 .statfs = simple_statfs,
333 .remount_fs = devpts_remount,
Miklos Szeredib87a2672008-02-08 04:21:41 -0800334 .show_options = devpts_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335};
336
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000337static void *new_pts_fs_info(void)
338{
339 struct pts_fs_info *fsi;
340
341 fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
342 if (!fsi)
343 return NULL;
344
345 ida_init(&fsi->allocated_ptys);
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000346 fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000347 fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000348
349 return fsi;
350}
351
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352static int
353devpts_fill_super(struct super_block *s, void *data, int silent)
354{
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000355 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
357 s->s_blocksize = 1024;
358 s->s_blocksize_bits = 10;
359 s->s_magic = DEVPTS_SUPER_MAGIC;
360 s->s_op = &devpts_sops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 s->s_time_gran = 1;
362
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000363 s->s_fs_info = new_pts_fs_info();
364 if (!s->s_fs_info)
365 goto fail;
366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 inode = new_inode(s);
368 if (!inode)
Al Viro3850aba2012-01-08 19:40:27 -0500369 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 inode->i_ino = 1;
371 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
373 inode->i_op = &simple_dir_inode_operations;
374 inode->i_fop = &simple_dir_operations;
Miklos Szeredibfe86842011-10-28 14:13:29 +0200375 set_nlink(inode, 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
Al Viro48fde702012-01-08 22:15:13 -0500377 s->s_root = d_make_root(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 if (s->s_root)
379 return 0;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000380
Alan Cox835aa442009-01-02 13:42:48 +0000381 printk(KERN_ERR "devpts: get root dentry failed\n");
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000382
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383fail:
384 return -ENOMEM;
385}
386
Andrew Morton8c056e52009-01-02 13:44:12 +0000387#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000388static int compare_init_pts_sb(struct super_block *s, void *p)
389{
390 if (devpts_mnt)
391 return devpts_mnt->mnt_sb == s;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000392 return 0;
393}
394
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000395/*
Al Virofc14f2f2010-07-25 01:48:30 +0400396 * devpts_mount()
Sukadev Bhattiprolu289f00e2009-03-07 10:12:06 -0800397 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800398 * If the '-o newinstance' mount option was specified, mount a new
399 * (private) instance of devpts. PTYs created in this instance are
400 * independent of the PTYs in other devpts instances.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000401 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800402 * If the '-o newinstance' option was not specified, mount/remount the
403 * initial kernel mount of devpts. This type of mount gives the
404 * legacy, single-instance semantics.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000405 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800406 * The 'newinstance' option is needed to support multiple namespace
407 * semantics in devpts while preserving backward compatibility of the
408 * current 'single-namespace' semantics. i.e all mounts of devpts
409 * without the 'newinstance' mount option should bind to the initial
Al Virofc14f2f2010-07-25 01:48:30 +0400410 * kernel mount, like mount_single().
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000411 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800412 * Mounts with 'newinstance' option create a new, private namespace.
413 *
414 * NOTE:
415 *
Al Virofc14f2f2010-07-25 01:48:30 +0400416 * For single-mount semantics, devpts cannot use mount_single(),
417 * because mount_single()/sget() find and use the super-block from
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000418 * the most recent mount of devpts. But that recent mount may be a
Al Virofc14f2f2010-07-25 01:48:30 +0400419 * 'newinstance' mount and mount_single() would pick the newinstance
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000420 * super-block instead of the initial super-block.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000421 */
Al Virofc14f2f2010-07-25 01:48:30 +0400422static struct dentry *devpts_mount(struct file_system_type *fs_type,
423 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424{
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800425 int error;
426 struct pts_mount_opts opts;
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800427 struct super_block *s;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000428
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -0700429 error = parse_mount_options(data, PARSE_MOUNT, &opts);
430 if (error)
Al Virofc14f2f2010-07-25 01:48:30 +0400431 return ERR_PTR(error);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000432
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800433 if (opts.newinstance)
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800434 s = sget(fs_type, NULL, set_anon_super, NULL);
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800435 else
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800436 s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800437
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800438 if (IS_ERR(s))
Al Virofc14f2f2010-07-25 01:48:30 +0400439 return ERR_CAST(s);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800440
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800441 if (!s->s_root) {
442 s->s_flags = flags;
443 error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
444 if (error)
445 goto out_undo_sget;
446 s->s_flags |= MS_ACTIVE;
447 }
448
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800449 memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
450
451 error = mknod_ptmx(s);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800452 if (error)
Al Viro89468072010-03-20 21:57:43 -0400453 goto out_undo_sget;
454
Al Virofc14f2f2010-07-25 01:48:30 +0400455 return dget(s->s_root);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800456
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800457out_undo_sget:
Al Viro6f5bbff2009-05-06 01:34:22 -0400458 deactivate_locked_super(s);
Al Virofc14f2f2010-07-25 01:48:30 +0400459 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460}
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800461
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000462#else
463/*
464 * This supports only the legacy single-instance semantics (no
465 * multiple-instance semantics)
466 */
Al Virofc14f2f2010-07-25 01:48:30 +0400467static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags,
468 const char *dev_name, void *data)
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000469{
Al Virofc14f2f2010-07-25 01:48:30 +0400470 return mount_single(fs_type, flags, data, devpts_fill_super);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000471}
472#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000474static void devpts_kill_sb(struct super_block *sb)
475{
476 struct pts_fs_info *fsi = DEVPTS_SB(sb);
477
478 kfree(fsi);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000479 kill_litter_super(sb);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000480}
481
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482static struct file_system_type devpts_fs_type = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 .name = "devpts",
Al Virofc14f2f2010-07-25 01:48:30 +0400484 .mount = devpts_mount,
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000485 .kill_sb = devpts_kill_sb,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486};
487
488/*
489 * The normal naming convention is simply /dev/pts/<number>; this conforms
490 * to the System V naming convention
491 */
492
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100493int devpts_new_index(struct inode *ptmx_inode)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700494{
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000495 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
496 struct pts_fs_info *fsi = DEVPTS_SB(sb);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700497 int index;
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400498 int ida_ret;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700499
500retry:
Alan Cox835aa442009-01-02 13:42:48 +0000501 if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700502 return -ENOMEM;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700503
504 mutex_lock(&allocated_ptys_lock);
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400505 if (pty_count >= pty_limit -
506 (fsi->mount_opts.newinstance ? pty_reserve : 0)) {
507 mutex_unlock(&allocated_ptys_lock);
508 return -ENOSPC;
509 }
510
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000511 ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400512 if (ida_ret < 0) {
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700513 mutex_unlock(&allocated_ptys_lock);
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400514 if (ida_ret == -EAGAIN)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700515 goto retry;
516 return -EIO;
517 }
518
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400519 if (index >= fsi->mount_opts.max) {
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000520 ida_remove(&fsi->allocated_ptys, index);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700521 mutex_unlock(&allocated_ptys_lock);
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400522 return -ENOSPC;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700523 }
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400524 pty_count++;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700525 mutex_unlock(&allocated_ptys_lock);
526 return index;
527}
528
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100529void devpts_kill_index(struct inode *ptmx_inode, int idx)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700530{
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000531 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
532 struct pts_fs_info *fsi = DEVPTS_SB(sb);
533
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700534 mutex_lock(&allocated_ptys_lock);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000535 ida_remove(&fsi->allocated_ptys, idx);
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400536 pty_count--;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700537 mutex_unlock(&allocated_ptys_lock);
538}
539
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100540int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541{
Alan Cox835aa442009-01-02 13:42:48 +0000542 /* tty layer puts index from devpts_new_index() in here */
543 int number = tty->index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 struct tty_driver *driver = tty->driver;
545 dev_t device = MKDEV(driver->major, driver->minor_start+number);
546 struct dentry *dentry;
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000547 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
548 struct inode *inode = new_inode(sb);
549 struct dentry *root = sb->s_root;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000550 struct pts_fs_info *fsi = DEVPTS_SB(sb);
551 struct pts_mount_opts *opts = &fsi->mount_opts;
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300552 int ret = 0;
Sukadev Bhattiprolu89a52e12008-10-13 10:43:18 +0100553 char s[12];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554
555 /* We're supposed to be given the slave end of a pty */
556 BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
557 BUG_ON(driver->subtype != PTY_TYPE_SLAVE);
558
559 if (!inode)
560 return -ENOMEM;
561
David Howellsd0eafc72009-01-02 13:44:49 +0000562 inode->i_ino = number + 3;
563 inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
564 inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000566 init_special_inode(inode, S_IFCHR|opts->mode, device);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700567 inode->i_private = tty;
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100568 tty->driver_data = inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569
Sukadev Bhattiprolu89a52e12008-10-13 10:43:18 +0100570 sprintf(s, "%d", number);
571
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000572 mutex_lock(&root->d_inode->i_mutex);
Sukadev Bhattiprolu89a52e12008-10-13 10:43:18 +0100573
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000574 dentry = d_alloc_name(root, s);
Andrey Vaginb12d1252011-03-22 16:35:11 -0700575 if (dentry) {
Sukadev Bhattiprolu89a52e12008-10-13 10:43:18 +0100576 d_add(dentry, inode);
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000577 fsnotify_create(root->d_inode, dentry);
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300578 } else {
579 iput(inode);
580 ret = -ENOMEM;
Florin Malita3972b7f2007-05-08 00:24:18 -0700581 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000583 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300585 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586}
587
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100588struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589{
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800590 struct dentry *dentry;
591 struct tty_struct *tty;
592
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +0100593 BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800595 /* Ensure dentry has not been deleted by devpts_pty_kill() */
596 dentry = d_find_alias(pts_inode);
597 if (!dentry)
598 return NULL;
599
600 tty = NULL;
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +0100601 if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800602 tty = (struct tty_struct *)pts_inode->i_private;
603
604 dput(dentry);
605
606 return tty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607}
608
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100609void devpts_pty_kill(struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610{
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100611 struct inode *inode = tty->driver_data;
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000612 struct super_block *sb = pts_sb_from_inode(inode);
613 struct dentry *root = sb->s_root;
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100614 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100616 BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
617
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000618 mutex_lock(&root->d_inode->i_mutex);
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100619
620 dentry = d_find_alias(inode);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000621
Miklos Szeredi6d6b77f2011-10-28 14:13:28 +0200622 drop_nlink(inode);
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300623 d_delete(dentry);
624 dput(dentry); /* d_alloc_name() in devpts_pty_new() */
Alan Cox835aa442009-01-02 13:42:48 +0000625 dput(dentry); /* d_find_alias above */
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300626
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000627 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628}
629
630static int __init init_devpts_fs(void)
631{
632 int err = register_filesystem(&devpts_fs_type);
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400633 struct ctl_table_header *table;
634
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 if (!err) {
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400636 table = register_sysctl_table(pty_root_table);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 devpts_mnt = kern_mount(&devpts_fs_type);
Alan Cox93d55812009-06-11 14:03:55 +0100638 if (IS_ERR(devpts_mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 err = PTR_ERR(devpts_mnt);
Alan Cox93d55812009-06-11 14:03:55 +0100640 unregister_filesystem(&devpts_fs_type);
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400641 unregister_sysctl_table(table);
Alan Cox93d55812009-06-11 14:03:55 +0100642 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 }
644 return err;
645}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646module_init(init_devpts_fs)