blob: add566303c684336cce3d8f9c4fa0f98678adafc [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
Fabian Frederick04541a22014-06-06 14:37:34 -070013#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/module.h>
16#include <linux/init.h>
17#include <linux/fs.h>
18#include <linux/sched.h>
19#include <linux/namei.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090020#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/mount.h>
22#include <linux/tty.h>
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070023#include <linux/mutex.h>
Nick Black1fd7317d2009-09-22 16:43:33 -070024#include <linux/magic.h>
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070025#include <linux/idr.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/devpts_fs.h>
Domen Puncer7a673c62006-03-23 03:00:59 -080027#include <linux/parser.h>
Florin Malita3972b7f2007-05-08 00:24:18 -070028#include <linux/fsnotify.h>
Miklos Szeredib87a2672008-02-08 04:21:41 -080029#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Miklos Szeredib87a2672008-02-08 04:21:41 -080031#define DEVPTS_DEFAULT_MODE 0600
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +000032/*
33 * ptmx is a new node in /dev/pts and will be unused in legacy (single-
34 * instance) mode. To prevent surprises in user space, set permissions of
35 * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful
36 * permissions.
37 */
38#define DEVPTS_DEFAULT_PTMX_MODE 0000
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +010039#define PTMX_MINOR 2
Miklos Szeredib87a2672008-02-08 04:21:41 -080040
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040041/*
42 * sysctl support for setting limits on the number of Unix98 ptys allocated.
43 * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
44 */
45static int pty_limit = NR_UNIX98_PTY_DEFAULT;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +040046static int pty_reserve = NR_UNIX98_PTY_RESERVE;
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040047static int pty_limit_min;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +040048static int pty_limit_max = INT_MAX;
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040049static int pty_count;
50
51static struct ctl_table pty_table[] = {
52 {
53 .procname = "max",
54 .maxlen = sizeof(int),
55 .mode = 0644,
56 .data = &pty_limit,
57 .proc_handler = proc_dointvec_minmax,
58 .extra1 = &pty_limit_min,
59 .extra2 = &pty_limit_max,
60 }, {
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +040061 .procname = "reserve",
62 .maxlen = sizeof(int),
63 .mode = 0644,
64 .data = &pty_reserve,
65 .proc_handler = proc_dointvec_minmax,
66 .extra1 = &pty_limit_min,
67 .extra2 = &pty_limit_max,
68 }, {
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +040069 .procname = "nr",
70 .maxlen = sizeof(int),
71 .mode = 0444,
72 .data = &pty_count,
73 .proc_handler = proc_dointvec,
74 },
75 {}
76};
77
78static struct ctl_table pty_kern_table[] = {
79 {
80 .procname = "pty",
81 .mode = 0555,
82 .child = pty_table,
83 },
84 {}
85};
86
87static struct ctl_table pty_root_table[] = {
88 {
89 .procname = "kernel",
90 .mode = 0555,
91 .child = pty_kern_table,
92 },
93 {}
94};
95
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -070096static DEFINE_MUTEX(allocated_ptys_lock);
97
Linus Torvalds1da177e2005-04-16 15:20:36 -070098static struct vfsmount *devpts_mnt;
Linus Torvalds1da177e2005-04-16 15:20:36 -070099
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000100struct pts_mount_opts {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 int setuid;
102 int setgid;
Eric W. Biedermanf04c6ce2012-02-07 16:22:56 -0800103 kuid_t uid;
104 kgid_t gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 umode_t mode;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000106 umode_t ptmxmode;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000107 int newinstance;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400108 int max;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000109};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110
Domen Puncer7a673c62006-03-23 03:00:59 -0800111enum {
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400112 Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance, Opt_max,
Domen Puncer7a673c62006-03-23 03:00:59 -0800113 Opt_err
114};
115
Steven Whitehousea447c092008-10-13 10:46:57 +0100116static const match_table_t tokens = {
Domen Puncer7a673c62006-03-23 03:00:59 -0800117 {Opt_uid, "uid=%u"},
118 {Opt_gid, "gid=%u"},
119 {Opt_mode, "mode=%o"},
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000120#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
121 {Opt_ptmxmode, "ptmxmode=%o"},
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000122 {Opt_newinstance, "newinstance"},
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400123 {Opt_max, "max=%d"},
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000124#endif
Domen Puncer7a673c62006-03-23 03:00:59 -0800125 {Opt_err, NULL}
126};
127
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000128struct pts_fs_info {
129 struct ida allocated_ptys;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000130 struct pts_mount_opts mount_opts;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000131 struct dentry *ptmx_dentry;
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000132};
133
134static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
135{
136 return sb->s_fs_info;
137}
138
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000139static inline struct super_block *pts_sb_from_inode(struct inode *inode)
140{
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000141#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000142 if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
143 return inode->i_sb;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000144#endif
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000145 return devpts_mnt->mnt_sb;
146}
147
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000148#define PARSE_MOUNT 0
149#define PARSE_REMOUNT 1
150
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -0700151/*
152 * parse_mount_options():
Fabian Frederick04541a22014-06-06 14:37:34 -0700153 * Set @opts to mount options specified in @data. If an option is not
154 * specified in @data, set it to its default value. The exception is
155 * 'newinstance' option which can only be set/cleared on a mount (i.e.
156 * cannot be changed during remount).
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -0700157 *
158 * Note: @data may be NULL (in which case all options are set to default).
159 */
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000160static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161{
Domen Puncer7a673c62006-03-23 03:00:59 -0800162 char *p;
Eric W. Biedermanf04c6ce2012-02-07 16:22:56 -0800163 kuid_t uid;
164 kgid_t gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000166 opts->setuid = 0;
167 opts->setgid = 0;
Eric W. Biedermanf04c6ce2012-02-07 16:22:56 -0800168 opts->uid = GLOBAL_ROOT_UID;
169 opts->gid = GLOBAL_ROOT_GID;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000170 opts->mode = DEVPTS_DEFAULT_MODE;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000171 opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400172 opts->max = NR_UNIX98_PTY_MAX;
Domen Puncer7a673c62006-03-23 03:00:59 -0800173
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000174 /* newinstance makes sense only on initial mount */
175 if (op == PARSE_MOUNT)
176 opts->newinstance = 0;
177
Domen Puncer7a673c62006-03-23 03:00:59 -0800178 while ((p = strsep(&data, ",")) != NULL) {
179 substring_t args[MAX_OPT_ARGS];
180 int token;
181 int option;
182
183 if (!*p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 continue;
Domen Puncer7a673c62006-03-23 03:00:59 -0800185
186 token = match_token(p, tokens, args);
187 switch (token) {
188 case Opt_uid:
189 if (match_int(&args[0], &option))
190 return -EINVAL;
Eric W. Biedermanf04c6ce2012-02-07 16:22:56 -0800191 uid = make_kuid(current_user_ns(), option);
192 if (!uid_valid(uid))
193 return -EINVAL;
194 opts->uid = uid;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000195 opts->setuid = 1;
Domen Puncer7a673c62006-03-23 03:00:59 -0800196 break;
197 case Opt_gid:
198 if (match_int(&args[0], &option))
199 return -EINVAL;
Eric W. Biedermanf04c6ce2012-02-07 16:22:56 -0800200 gid = make_kgid(current_user_ns(), option);
201 if (!gid_valid(gid))
202 return -EINVAL;
203 opts->gid = gid;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000204 opts->setgid = 1;
Domen Puncer7a673c62006-03-23 03:00:59 -0800205 break;
206 case Opt_mode:
207 if (match_octal(&args[0], &option))
208 return -EINVAL;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000209 opts->mode = option & S_IALLUGO;
Domen Puncer7a673c62006-03-23 03:00:59 -0800210 break;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000211#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
212 case Opt_ptmxmode:
213 if (match_octal(&args[0], &option))
214 return -EINVAL;
215 opts->ptmxmode = option & S_IALLUGO;
216 break;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000217 case Opt_newinstance:
218 /* newinstance makes sense only on initial mount */
219 if (op == PARSE_MOUNT)
220 opts->newinstance = 1;
221 break;
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400222 case Opt_max:
223 if (match_int(&args[0], &option) ||
224 option < 0 || option > NR_UNIX98_PTY_MAX)
225 return -EINVAL;
226 opts->max = option;
227 break;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000228#endif
Domen Puncer7a673c62006-03-23 03:00:59 -0800229 default:
Fabian Frederick04541a22014-06-06 14:37:34 -0700230 pr_err("called with bogus options\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 return -EINVAL;
232 }
233 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
235 return 0;
236}
237
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000238#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
239static int mknod_ptmx(struct super_block *sb)
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000240{
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000241 int mode;
242 int rc = -ENOMEM;
243 struct dentry *dentry;
244 struct inode *inode;
245 struct dentry *root = sb->s_root;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000246 struct pts_fs_info *fsi = DEVPTS_SB(sb);
247 struct pts_mount_opts *opts = &fsi->mount_opts;
Eric W. Biedermanec2aa8e2012-08-20 17:28:58 -0700248 kuid_t root_uid;
249 kgid_t root_gid;
250
251 root_uid = make_kuid(current_user_ns(), 0);
252 root_gid = make_kgid(current_user_ns(), 0);
253 if (!uid_valid(root_uid) || !gid_valid(root_gid))
254 return -EINVAL;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000255
David Howells2b0143b2015-03-17 22:25:59 +0000256 mutex_lock(&d_inode(root)->i_mutex);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000257
258 /* If we have already created ptmx node, return */
259 if (fsi->ptmx_dentry) {
260 rc = 0;
261 goto out;
262 }
263
264 dentry = d_alloc_name(root, "ptmx");
265 if (!dentry) {
Fabian Frederick04541a22014-06-06 14:37:34 -0700266 pr_err("Unable to alloc dentry for ptmx node\n");
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000267 goto out;
268 }
269
270 /*
271 * Create a new 'ptmx' node in this mount of devpts.
272 */
273 inode = new_inode(sb);
274 if (!inode) {
Fabian Frederick04541a22014-06-06 14:37:34 -0700275 pr_err("Unable to alloc inode for ptmx node\n");
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000276 dput(dentry);
277 goto out;
278 }
279
280 inode->i_ino = 2;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000281 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
282
283 mode = S_IFCHR|opts->ptmxmode;
284 init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
Eric W. Biedermanec2aa8e2012-08-20 17:28:58 -0700285 inode->i_uid = root_uid;
286 inode->i_gid = root_gid;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000287
288 d_add(dentry, inode);
289
290 fsi->ptmx_dentry = dentry;
291 rc = 0;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000292out:
David Howells2b0143b2015-03-17 22:25:59 +0000293 mutex_unlock(&d_inode(root)->i_mutex);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000294 return rc;
295}
296
297static void update_ptmx_mode(struct pts_fs_info *fsi)
298{
299 struct inode *inode;
300 if (fsi->ptmx_dentry) {
David Howells2b0143b2015-03-17 22:25:59 +0000301 inode = d_inode(fsi->ptmx_dentry);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000302 inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;
303 }
304}
305#else
306static inline void update_ptmx_mode(struct pts_fs_info *fsi)
307{
Fabian Frederick04541a22014-06-06 14:37:34 -0700308 return;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000309}
310#endif
311
312static int devpts_remount(struct super_block *sb, int *flags, char *data)
313{
314 int err;
315 struct pts_fs_info *fsi = DEVPTS_SB(sb);
316 struct pts_mount_opts *opts = &fsi->mount_opts;
317
Theodore Ts'o02b99842014-03-13 10:14:33 -0400318 sync_filesystem(sb);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000319 err = parse_mount_options(data, PARSE_REMOUNT, opts);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000320
321 /*
322 * parse_mount_options() restores options to default values
323 * before parsing and may have changed ptmxmode. So, update the
324 * mode in the inode too. Bogus options don't fail the remount,
325 * so do this even on error return.
326 */
327 update_ptmx_mode(fsi);
328
329 return err;
Sukadev Bhattiprolu53af8ee2009-01-02 13:41:47 +0000330}
331
Al Viro34c80b12011-12-08 21:32:45 -0500332static int devpts_show_options(struct seq_file *seq, struct dentry *root)
Miklos Szeredib87a2672008-02-08 04:21:41 -0800333{
Al Viro34c80b12011-12-08 21:32:45 -0500334 struct pts_fs_info *fsi = DEVPTS_SB(root->d_sb);
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000335 struct pts_mount_opts *opts = &fsi->mount_opts;
336
337 if (opts->setuid)
Fabian Frederick04541a22014-06-06 14:37:34 -0700338 seq_printf(seq, ",uid=%u",
339 from_kuid_munged(&init_user_ns, opts->uid));
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000340 if (opts->setgid)
Fabian Frederick04541a22014-06-06 14:37:34 -0700341 seq_printf(seq, ",gid=%u",
342 from_kgid_munged(&init_user_ns, opts->gid));
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000343 seq_printf(seq, ",mode=%03o", opts->mode);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000344#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
345 seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400346 if (opts->max < NR_UNIX98_PTY_MAX)
347 seq_printf(seq, ",max=%d", opts->max);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000348#endif
Miklos Szeredib87a2672008-02-08 04:21:41 -0800349
350 return 0;
351}
352
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800353static const struct super_operations devpts_sops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 .statfs = simple_statfs,
355 .remount_fs = devpts_remount,
Miklos Szeredib87a2672008-02-08 04:21:41 -0800356 .show_options = devpts_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357};
358
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000359static void *new_pts_fs_info(void)
360{
361 struct pts_fs_info *fsi;
362
363 fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
364 if (!fsi)
365 return NULL;
366
367 ida_init(&fsi->allocated_ptys);
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000368 fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000369 fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000370
371 return fsi;
372}
373
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374static int
375devpts_fill_super(struct super_block *s, void *data, int silent)
376{
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000377 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378
379 s->s_blocksize = 1024;
380 s->s_blocksize_bits = 10;
381 s->s_magic = DEVPTS_SUPER_MAGIC;
382 s->s_op = &devpts_sops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 s->s_time_gran = 1;
384
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000385 s->s_fs_info = new_pts_fs_info();
386 if (!s->s_fs_info)
387 goto fail;
388
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 inode = new_inode(s);
390 if (!inode)
Al Viro3850aba2012-01-08 19:40:27 -0500391 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 inode->i_ino = 1;
393 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
395 inode->i_op = &simple_dir_inode_operations;
396 inode->i_fop = &simple_dir_operations;
Miklos Szeredibfe86842011-10-28 14:13:29 +0200397 set_nlink(inode, 2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398
Al Viro48fde702012-01-08 22:15:13 -0500399 s->s_root = d_make_root(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 if (s->s_root)
401 return 0;
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000402
Fabian Frederick04541a22014-06-06 14:37:34 -0700403 pr_err("get root dentry failed\n");
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000404
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405fail:
406 return -ENOMEM;
407}
408
Andrew Morton8c056e52009-01-02 13:44:12 +0000409#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000410static int compare_init_pts_sb(struct super_block *s, void *p)
411{
412 if (devpts_mnt)
413 return devpts_mnt->mnt_sb == s;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000414 return 0;
415}
416
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000417/*
Al Virofc14f2f2010-07-25 01:48:30 +0400418 * devpts_mount()
Sukadev Bhattiprolu289f00e2009-03-07 10:12:06 -0800419 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800420 * If the '-o newinstance' mount option was specified, mount a new
421 * (private) instance of devpts. PTYs created in this instance are
422 * independent of the PTYs in other devpts instances.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000423 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800424 * If the '-o newinstance' option was not specified, mount/remount the
425 * initial kernel mount of devpts. This type of mount gives the
426 * legacy, single-instance semantics.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000427 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800428 * The 'newinstance' option is needed to support multiple namespace
429 * semantics in devpts while preserving backward compatibility of the
430 * current 'single-namespace' semantics. i.e all mounts of devpts
431 * without the 'newinstance' mount option should bind to the initial
Al Virofc14f2f2010-07-25 01:48:30 +0400432 * kernel mount, like mount_single().
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000433 *
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800434 * Mounts with 'newinstance' option create a new, private namespace.
435 *
436 * NOTE:
437 *
Al Virofc14f2f2010-07-25 01:48:30 +0400438 * For single-mount semantics, devpts cannot use mount_single(),
439 * because mount_single()/sget() find and use the super-block from
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000440 * the most recent mount of devpts. But that recent mount may be a
Al Virofc14f2f2010-07-25 01:48:30 +0400441 * 'newinstance' mount and mount_single() would pick the newinstance
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000442 * super-block instead of the initial super-block.
Sukadev Bhattiprolud4076ac2009-01-02 13:42:19 +0000443 */
Al Virofc14f2f2010-07-25 01:48:30 +0400444static struct dentry *devpts_mount(struct file_system_type *fs_type,
445 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446{
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800447 int error;
448 struct pts_mount_opts opts;
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800449 struct super_block *s;
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000450
Sukadev Bhattiprolu1f71ebe2009-05-14 19:38:24 -0700451 error = parse_mount_options(data, PARSE_MOUNT, &opts);
452 if (error)
Al Virofc14f2f2010-07-25 01:48:30 +0400453 return ERR_PTR(error);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000454
Eric W. Biedermanec2aa8e2012-08-20 17:28:58 -0700455 /* Require newinstance for all user namespace mounts to ensure
456 * the mount options are not changed.
457 */
458 if ((current_user_ns() != &init_user_ns) && !opts.newinstance)
459 return ERR_PTR(-EINVAL);
460
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800461 if (opts.newinstance)
David Howells9249e172012-06-25 12:55:37 +0100462 s = sget(fs_type, NULL, set_anon_super, flags, NULL);
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800463 else
David Howells9249e172012-06-25 12:55:37 +0100464 s = sget(fs_type, compare_init_pts_sb, set_anon_super, flags,
465 NULL);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800466
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800467 if (IS_ERR(s))
Al Virofc14f2f2010-07-25 01:48:30 +0400468 return ERR_CAST(s);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800469
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800470 if (!s->s_root) {
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800471 error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
472 if (error)
473 goto out_undo_sget;
474 s->s_flags |= MS_ACTIVE;
475 }
476
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800477 memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
478
479 error = mknod_ptmx(s);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800480 if (error)
Al Viro89468072010-03-20 21:57:43 -0400481 goto out_undo_sget;
482
Al Virofc14f2f2010-07-25 01:48:30 +0400483 return dget(s->s_root);
Sukadev Bhattiprolu945cf2c2009-03-07 10:11:41 -0800484
Sukadev Bhattiprolu1bd79032009-03-07 10:12:32 -0800485out_undo_sget:
Al Viro6f5bbff2009-05-06 01:34:22 -0400486 deactivate_locked_super(s);
Al Virofc14f2f2010-07-25 01:48:30 +0400487 return ERR_PTR(error);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488}
Sukadev Bhattiprolu482984f2009-03-07 10:14:41 -0800489
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000490#else
491/*
492 * This supports only the legacy single-instance semantics (no
493 * multiple-instance semantics)
494 */
Al Virofc14f2f2010-07-25 01:48:30 +0400495static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags,
496 const char *dev_name, void *data)
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000497{
Al Virofc14f2f2010-07-25 01:48:30 +0400498 return mount_single(fs_type, flags, data, devpts_fill_super);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000499}
500#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000502static void devpts_kill_sb(struct super_block *sb)
503{
504 struct pts_fs_info *fsi = DEVPTS_SB(sb);
505
Ilija Hadzic66da0e12013-11-12 15:11:45 -0800506 ida_destroy(&fsi->allocated_ptys);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000507 kfree(fsi);
Sukadev Bhattiprolu1f8f1e22009-01-02 13:42:02 +0000508 kill_litter_super(sb);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000509}
510
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511static struct file_system_type devpts_fs_type = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 .name = "devpts",
Al Virofc14f2f2010-07-25 01:48:30 +0400513 .mount = devpts_mount,
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000514 .kill_sb = devpts_kill_sb,
Eric W. Biedermanec2aa8e2012-08-20 17:28:58 -0700515#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
516 .fs_flags = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
517#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518};
519
520/*
521 * The normal naming convention is simply /dev/pts/<number>; this conforms
522 * to the System V naming convention
523 */
524
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100525int devpts_new_index(struct inode *ptmx_inode)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700526{
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000527 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
528 struct pts_fs_info *fsi = DEVPTS_SB(sb);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700529 int index;
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400530 int ida_ret;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700531
532retry:
Alan Cox835aa442009-01-02 13:42:48 +0000533 if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700534 return -ENOMEM;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700535
536 mutex_lock(&allocated_ptys_lock);
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400537 if (pty_count >= pty_limit -
538 (fsi->mount_opts.newinstance ? pty_reserve : 0)) {
539 mutex_unlock(&allocated_ptys_lock);
540 return -ENOSPC;
541 }
542
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000543 ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400544 if (ida_ret < 0) {
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700545 mutex_unlock(&allocated_ptys_lock);
Alexey Dobriyan7ee7c122008-07-26 11:42:16 +0400546 if (ida_ret == -EAGAIN)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700547 goto retry;
548 return -EIO;
549 }
550
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400551 if (index >= fsi->mount_opts.max) {
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000552 ida_remove(&fsi->allocated_ptys, index);
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700553 mutex_unlock(&allocated_ptys_lock);
Konstantin Khlebnikove9aba512012-01-05 13:06:11 +0400554 return -ENOSPC;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700555 }
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400556 pty_count++;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700557 mutex_unlock(&allocated_ptys_lock);
558 return index;
559}
560
Sukadev Bhattiprolu15f1a632008-10-13 10:42:59 +0100561void devpts_kill_index(struct inode *ptmx_inode, int idx)
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700562{
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000563 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
564 struct pts_fs_info *fsi = DEVPTS_SB(sb);
565
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700566 mutex_lock(&allocated_ptys_lock);
Sukadev Bhattiprolue76b7c02009-01-02 13:41:21 +0000567 ida_remove(&fsi->allocated_ptys, idx);
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400568 pty_count--;
Sukadev Bhattiprolu718a9162008-04-30 00:54:21 -0700569 mutex_unlock(&allocated_ptys_lock);
570}
571
Jiri Slaby1dcb8e62012-10-18 22:26:30 +0200572/**
573 * devpts_pty_new -- create a new inode in /dev/pts/
574 * @ptmx_inode: inode of the master
575 * @device: major+minor of the node to be created
576 * @index: used as a name of the node
577 * @priv: what's given back by devpts_get_priv
578 *
579 * The created inode is returned. Remove it from /dev/pts/ by devpts_pty_kill.
580 */
Jiri Slabyf11afb62012-10-18 22:26:29 +0200581struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
582 void *priv)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 struct dentry *dentry;
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000585 struct super_block *sb = pts_sb_from_inode(ptmx_inode);
Jiri Slaby162b97c2012-10-18 22:26:28 +0200586 struct inode *inode;
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000587 struct dentry *root = sb->s_root;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000588 struct pts_fs_info *fsi = DEVPTS_SB(sb);
589 struct pts_mount_opts *opts = &fsi->mount_opts;
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100590 char s[12];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
Jiri Slaby162b97c2012-10-18 22:26:28 +0200592 inode = new_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 if (!inode)
Jiri Slaby162b97c2012-10-18 22:26:28 +0200594 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595
Jiri Slabyf11afb62012-10-18 22:26:29 +0200596 inode->i_ino = index + 3;
David Howellsd0eafc72009-01-02 13:44:49 +0000597 inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
598 inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
Sukadev Bhattiprolu31af0ab2009-01-02 13:41:33 +0000600 init_special_inode(inode, S_IFCHR|opts->mode, device);
Jiri Slabyf11afb62012-10-18 22:26:29 +0200601 inode->i_private = priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602
Jiri Slabyf11afb62012-10-18 22:26:29 +0200603 sprintf(s, "%d", index);
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100604
David Howells2b0143b2015-03-17 22:25:59 +0000605 mutex_lock(&d_inode(root)->i_mutex);
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100606
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000607 dentry = d_alloc_name(root, s);
Andrey Vaginb12d1252011-03-22 16:35:11 -0700608 if (dentry) {
Sukadev Bhattiprolu89a52e102008-10-13 10:43:18 +0100609 d_add(dentry, inode);
David Howells2b0143b2015-03-17 22:25:59 +0000610 fsnotify_create(d_inode(root), dentry);
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300611 } else {
612 iput(inode);
Jiri Slaby162b97c2012-10-18 22:26:28 +0200613 inode = ERR_PTR(-ENOMEM);
Florin Malita3972b7f2007-05-08 00:24:18 -0700614 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
David Howells2b0143b2015-03-17 22:25:59 +0000616 mutex_unlock(&d_inode(root)->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617
Jiri Slaby162b97c2012-10-18 22:26:28 +0200618 return inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619}
620
Jiri Slaby1dcb8e62012-10-18 22:26:30 +0200621/**
622 * devpts_get_priv -- get private data for a slave
623 * @pts_inode: inode of the slave
624 *
625 * Returns whatever was passed as priv in devpts_pty_new for a given inode.
626 */
Jiri Slaby8fcbaa22012-10-18 22:26:27 +0200627void *devpts_get_priv(struct inode *pts_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628{
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800629 struct dentry *dentry;
Jiri Slaby8fcbaa22012-10-18 22:26:27 +0200630 void *priv = NULL;
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800631
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +0100632 BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800634 /* Ensure dentry has not been deleted by devpts_pty_kill() */
635 dentry = d_find_alias(pts_inode);
636 if (!dentry)
637 return NULL;
638
Sukadev Bhattiprolu527b3e42008-10-13 10:43:08 +0100639 if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
Jiri Slaby8fcbaa22012-10-18 22:26:27 +0200640 priv = pts_inode->i_private;
Sukadev Bhattiproluedfacdd2009-11-17 18:35:43 -0800641
642 dput(dentry);
643
Jiri Slaby8fcbaa22012-10-18 22:26:27 +0200644 return priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645}
646
Jiri Slaby1dcb8e62012-10-18 22:26:30 +0200647/**
648 * devpts_pty_kill -- remove inode form /dev/pts/
649 * @inode: inode of the slave to be removed
650 *
651 * This is an inverse operation of devpts_pty_new.
652 */
Jiri Slabyf11afb62012-10-18 22:26:29 +0200653void devpts_pty_kill(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654{
Sukadev Bhattiprolu59e55e62009-01-02 13:41:11 +0000655 struct super_block *sb = pts_sb_from_inode(inode);
656 struct dentry *root = sb->s_root;
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100657 struct dentry *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100659 BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
660
David Howells2b0143b2015-03-17 22:25:59 +0000661 mutex_lock(&d_inode(root)->i_mutex);
Sukadev Bhattiprolua6f37da2008-10-13 10:43:27 +0100662
663 dentry = d_find_alias(inode);
Sukadev Bhattiprolu2a1b2dc2009-01-02 13:42:27 +0000664
Miklos Szeredi6d6b77f2011-10-28 14:13:28 +0200665 drop_nlink(inode);
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300666 d_delete(dentry);
667 dput(dentry); /* d_alloc_name() in devpts_pty_new() */
Alan Cox835aa442009-01-02 13:42:48 +0000668 dput(dentry); /* d_find_alias above */
Andrey Vaginaa597bc2011-02-08 00:14:52 +0300669
David Howells2b0143b2015-03-17 22:25:59 +0000670 mutex_unlock(&d_inode(root)->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671}
672
673static int __init init_devpts_fs(void)
674{
675 int err = register_filesystem(&devpts_fs_type);
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400676 struct ctl_table_header *table;
677
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 if (!err) {
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400679 table = register_sysctl_table(pty_root_table);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 devpts_mnt = kern_mount(&devpts_fs_type);
Alan Cox93d55812009-06-11 14:03:55 +0100681 if (IS_ERR(devpts_mnt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 err = PTR_ERR(devpts_mnt);
Alan Cox93d55812009-06-11 14:03:55 +0100683 unregister_filesystem(&devpts_fs_type);
Konstantin Khlebnikova4834c12012-01-05 13:06:02 +0400684 unregister_sysctl_table(table);
Alan Cox93d55812009-06-11 14:03:55 +0100685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 }
687 return err;
688}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689module_init(init_devpts_fs)