1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
4 * Copyright 2005-2006 Ian Kent <raven@themaw.net>
5 */
6
7#include <linux/seq_file.h>
8#include <linux/pagemap.h>
9
10#include "autofs_i.h"
11
12struct autofs_info *autofs_new_ino(struct autofs_sb_info *sbi)
13{
14	struct autofs_info *ino;
15
16	ino = kzalloc(sizeof(*ino), GFP_KERNEL);
17	if (ino) {
18		INIT_LIST_HEAD(&ino->active);
19		INIT_LIST_HEAD(&ino->expiring);
20		ino->last_used = jiffies;
21		ino->sbi = sbi;
22		ino->count = 1;
23	}
24	return ino;
25}
26
27void autofs_clean_ino(struct autofs_info *ino)
28{
29	ino->uid = GLOBAL_ROOT_UID;
30	ino->gid = GLOBAL_ROOT_GID;
31	ino->last_used = jiffies;
32}
33
34void autofs_free_ino(struct autofs_info *ino)
35{
36	kfree_rcu(ino, rcu);
37}
38
39void autofs_kill_sb(struct super_block *sb)
40{
41	struct autofs_sb_info *sbi = autofs_sbi(sb);
42
43	/*
44	 * In the event of a failure in get_sb_nodev the superblock
45	 * info is not present so nothing else has been setup, so
46	 * just call kill_anon_super when we are called from
47	 * deactivate_super.
48	 */
49	if (sbi) {
50		/* Free wait queues, close pipe */
51		autofs_catatonic_mode(sbi);
52		put_pid(sbi->oz_pgrp);
53	}
54
55	pr_debug("shutting down\n");
56	kill_litter_super(sb);
57	if (sbi)
58		kfree_rcu(sbi, rcu);
59}
60
61static int autofs_show_options(struct seq_file *m, struct dentry *root)
62{
63	struct autofs_sb_info *sbi = autofs_sbi(root->d_sb);
64	struct inode *root_inode = d_inode(root->d_sb->s_root);
65
66	if (!sbi)
67		return 0;
68
69	seq_printf(m, ",fd=%d", sbi->pipefd);
70	if (!uid_eq(root_inode->i_uid, GLOBAL_ROOT_UID))
71		seq_printf(m, ",uid=%u",
72			from_kuid_munged(&init_user_ns, root_inode->i_uid));
73	if (!gid_eq(root_inode->i_gid, GLOBAL_ROOT_GID))
74		seq_printf(m, ",gid=%u",
75			from_kgid_munged(&init_user_ns, root_inode->i_gid));
76	seq_printf(m, ",pgrp=%d", pid_vnr(sbi->oz_pgrp));
77	seq_printf(m, ",timeout=%lu", sbi->exp_timeout/HZ);
78	seq_printf(m, ",minproto=%d", sbi->min_proto);
79	seq_printf(m, ",maxproto=%d", sbi->max_proto);
80
81	if (autofs_type_offset(sbi->type))
82		seq_puts(m, ",offset");
83	else if (autofs_type_direct(sbi->type))
84		seq_puts(m, ",direct");
85	else
86		seq_puts(m, ",indirect");
87	if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE)
88		seq_puts(m, ",strictexpire");
89	if (sbi->flags & AUTOFS_SBI_IGNORE)
90		seq_puts(m, ",ignore");
91#ifdef CONFIG_CHECKPOINT_RESTORE
92	if (sbi->pipe)
93		seq_printf(m, ",pipe_ino=%ld", file_inode(sbi->pipe)->i_ino);
94	else
95		seq_puts(m, ",pipe_ino=-1");
96#endif
97	return 0;
98}
99
100static void autofs_evict_inode(struct inode *inode)
101{
102	clear_inode(inode);
103	kfree(inode->i_private);
104}
105
106static const struct super_operations autofs_sops = {
107	.statfs		= simple_statfs,
108	.show_options	= autofs_show_options,
109	.evict_inode	= autofs_evict_inode,
110};
111
112enum {
113	Opt_direct,
114	Opt_fd,
115	Opt_gid,
116	Opt_ignore,
117	Opt_indirect,
118	Opt_maxproto,
119	Opt_minproto,
120	Opt_offset,
121	Opt_pgrp,
122	Opt_strictexpire,
123	Opt_uid,
124};
125
126const struct fs_parameter_spec autofs_param_specs[] = {
127	fsparam_flag	("direct",		Opt_direct),
128	fsparam_fd	("fd",			Opt_fd),
129	fsparam_u32	("gid",			Opt_gid),
130	fsparam_flag	("ignore",		Opt_ignore),
131	fsparam_flag	("indirect",		Opt_indirect),
132	fsparam_u32	("maxproto",		Opt_maxproto),
133	fsparam_u32	("minproto",		Opt_minproto),
134	fsparam_flag	("offset",		Opt_offset),
135	fsparam_u32	("pgrp",		Opt_pgrp),
136	fsparam_flag	("strictexpire",	Opt_strictexpire),
137	fsparam_u32	("uid",			Opt_uid),
138	{}
139};
140
141struct autofs_fs_context {
142	kuid_t	uid;
143	kgid_t	gid;
144	int	pgrp;
145	bool	pgrp_set;
146};
147
148/*
149 * Open the fd.  We do it here rather than in get_tree so that it's done in the
150 * context of the system call that passed the data and not the one that
151 * triggered the superblock creation, lest the fd gets reassigned.
152 */
153static int autofs_parse_fd(struct fs_context *fc, struct autofs_sb_info *sbi,
154			   struct fs_parameter *param,
155			   struct fs_parse_result *result)
156{
157	struct file *pipe;
158	int ret;
159
160	if (param->type == fs_value_is_file) {
161		/* came through the new api */
162		pipe = param->file;
163		param->file = NULL;
164	} else {
165		pipe = fget(result->uint_32);
166	}
167	if (!pipe) {
168		errorf(fc, "could not open pipe file descriptor");
169		return -EBADF;
170	}
171
172	ret = autofs_check_pipe(pipe);
173	if (ret < 0) {
174		errorf(fc, "Invalid/unusable pipe");
175		if (param->type != fs_value_is_file)
176			fput(pipe);
177		return -EBADF;
178	}
179
180	autofs_set_packet_pipe_flags(pipe);
181
182	if (sbi->pipe)
183		fput(sbi->pipe);
184
185	sbi->pipefd = result->uint_32;
186	sbi->pipe = pipe;
187
188	return 0;
189}
190
191static int autofs_parse_param(struct fs_context *fc, struct fs_parameter *param)
192{
193	struct autofs_fs_context *ctx = fc->fs_private;
194	struct autofs_sb_info *sbi = fc->s_fs_info;
195	struct fs_parse_result result;
196	kuid_t uid;
197	kgid_t gid;
198	int opt;
199
200	opt = fs_parse(fc, autofs_param_specs, param, &result);
201	if (opt < 0)
202		return opt;
203
204	switch (opt) {
205	case Opt_fd:
206		return autofs_parse_fd(fc, sbi, param, &result);
207	case Opt_uid:
208		uid = make_kuid(current_user_ns(), result.uint_32);
209		if (!uid_valid(uid))
210			return invalfc(fc, "Invalid uid");
211		ctx->uid = uid;
212		break;
213	case Opt_gid:
214		gid = make_kgid(current_user_ns(), result.uint_32);
215		if (!gid_valid(gid))
216			return invalfc(fc, "Invalid gid");
217		ctx->gid = gid;
218		break;
219	case Opt_pgrp:
220		ctx->pgrp = result.uint_32;
221		ctx->pgrp_set = true;
222		break;
223	case Opt_minproto:
224		sbi->min_proto = result.uint_32;
225		break;
226	case Opt_maxproto:
227		sbi->max_proto = result.uint_32;
228		break;
229	case Opt_indirect:
230		set_autofs_type_indirect(&sbi->type);
231		break;
232	case Opt_direct:
233		set_autofs_type_direct(&sbi->type);
234		break;
235	case Opt_offset:
236		set_autofs_type_offset(&sbi->type);
237		break;
238	case Opt_strictexpire:
239		sbi->flags |= AUTOFS_SBI_STRICTEXPIRE;
240		break;
241	case Opt_ignore:
242		sbi->flags |= AUTOFS_SBI_IGNORE;
243	}
244
245	return 0;
246}
247
248static struct autofs_sb_info *autofs_alloc_sbi(void)
249{
250	struct autofs_sb_info *sbi;
251
252	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
253	if (!sbi)
254		return NULL;
255
256	sbi->magic = AUTOFS_SBI_MAGIC;
257	sbi->flags = AUTOFS_SBI_CATATONIC;
258	sbi->min_proto = AUTOFS_MIN_PROTO_VERSION;
259	sbi->max_proto = AUTOFS_MAX_PROTO_VERSION;
260	sbi->pipefd = -1;
261
262	set_autofs_type_indirect(&sbi->type);
263	mutex_init(&sbi->wq_mutex);
264	mutex_init(&sbi->pipe_mutex);
265	spin_lock_init(&sbi->fs_lock);
266	spin_lock_init(&sbi->lookup_lock);
267	INIT_LIST_HEAD(&sbi->active_list);
268	INIT_LIST_HEAD(&sbi->expiring_list);
269
270	return sbi;
271}
272
273static int autofs_validate_protocol(struct fs_context *fc)
274{
275	struct autofs_sb_info *sbi = fc->s_fs_info;
276
277	/* Test versions first */
278	if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
279	    sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) {
280		errorf(fc, "kernel does not match daemon version "
281		       "daemon (%d, %d) kernel (%d, %d)\n",
282		       sbi->min_proto, sbi->max_proto,
283		       AUTOFS_MIN_PROTO_VERSION, AUTOFS_MAX_PROTO_VERSION);
284		return -EINVAL;
285	}
286
287	/* Establish highest kernel protocol version */
288	if (sbi->max_proto > AUTOFS_MAX_PROTO_VERSION)
289		sbi->version = AUTOFS_MAX_PROTO_VERSION;
290	else
291		sbi->version = sbi->max_proto;
292
293	switch (sbi->version) {
294	case 4:
295		sbi->sub_version = 7;
296		break;
297	case 5:
298		sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
299		break;
300	default:
301		sbi->sub_version = 0;
302	}
303
304	return 0;
305}
306
307static int autofs_fill_super(struct super_block *s, struct fs_context *fc)
308{
309	struct autofs_fs_context *ctx = fc->fs_private;
310	struct autofs_sb_info *sbi = s->s_fs_info;
311	struct inode *root_inode;
312	struct autofs_info *ino;
313
314	pr_debug("starting up, sbi = %p\n", sbi);
315
316	sbi->sb = s;
317	s->s_blocksize = 1024;
318	s->s_blocksize_bits = 10;
319	s->s_magic = AUTOFS_SUPER_MAGIC;
320	s->s_op = &autofs_sops;
321	s->s_d_op = &autofs_dentry_operations;
322	s->s_time_gran = 1;
323
324	/*
325	 * Get the root inode and dentry, but defer checking for errors.
326	 */
327	ino = autofs_new_ino(sbi);
328	if (!ino)
329		return -ENOMEM;
330
331	root_inode = autofs_get_inode(s, S_IFDIR | 0755);
332	if (!root_inode)
333		return -ENOMEM;
334
335	root_inode->i_uid = ctx->uid;
336	root_inode->i_gid = ctx->gid;
337	root_inode->i_fop = &autofs_root_operations;
338	root_inode->i_op = &autofs_dir_inode_operations;
339
340	s->s_root = d_make_root(root_inode);
341	if (unlikely(!s->s_root)) {
342		autofs_free_ino(ino);
343		return -ENOMEM;
344	}
345	s->s_root->d_fsdata = ino;
346
347	if (ctx->pgrp_set) {
348		sbi->oz_pgrp = find_get_pid(ctx->pgrp);
349		if (!sbi->oz_pgrp)
350			return invalf(fc, "Could not find process group %d",
351				      ctx->pgrp);
352	} else
353		sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID);
354
355	if (autofs_type_trigger(sbi->type))
356		/* s->s_root won't be contended so there's little to
357		 * be gained by not taking the d_lock when setting
358		 * d_flags, even when a lot mounts are being done.
359		 */
360		managed_dentry_set_managed(s->s_root);
361
362	pr_debug("pipe fd = %d, pgrp = %u\n",
363		 sbi->pipefd, pid_nr(sbi->oz_pgrp));
364
365	sbi->flags &= ~AUTOFS_SBI_CATATONIC;
366	return 0;
367}
368
369/*
370 * Validate the parameters and then request a superblock.
371 */
372static int autofs_get_tree(struct fs_context *fc)
373{
374	struct autofs_sb_info *sbi = fc->s_fs_info;
375	int ret;
376
377	ret = autofs_validate_protocol(fc);
378	if (ret)
379		return ret;
380
381	if (sbi->pipefd < 0)
382		return invalf(fc, "No control pipe specified");
383
384	return get_tree_nodev(fc, autofs_fill_super);
385}
386
387static void autofs_free_fc(struct fs_context *fc)
388{
389	struct autofs_fs_context *ctx = fc->fs_private;
390	struct autofs_sb_info *sbi = fc->s_fs_info;
391
392	if (sbi) {
393		if (sbi->pipe)
394			fput(sbi->pipe);
395		kfree(sbi);
396	}
397	kfree(ctx);
398}
399
400static const struct fs_context_operations autofs_context_ops = {
401	.free		= autofs_free_fc,
402	.parse_param	= autofs_parse_param,
403	.get_tree	= autofs_get_tree,
404};
405
406/*
407 * Set up the filesystem mount context.
408 */
409int autofs_init_fs_context(struct fs_context *fc)
410{
411	struct autofs_fs_context *ctx;
412	struct autofs_sb_info *sbi;
413
414	ctx = kzalloc(sizeof(struct autofs_fs_context), GFP_KERNEL);
415	if (!ctx)
416		goto nomem;
417
418	ctx->uid = current_uid();
419	ctx->gid = current_gid();
420
421	sbi = autofs_alloc_sbi();
422	if (!sbi)
423		goto nomem_ctx;
424
425	fc->fs_private = ctx;
426	fc->s_fs_info = sbi;
427	fc->ops = &autofs_context_ops;
428	return 0;
429
430nomem_ctx:
431	kfree(ctx);
432nomem:
433	return -ENOMEM;
434}
435
436struct inode *autofs_get_inode(struct super_block *sb, umode_t mode)
437{
438	struct inode *inode = new_inode(sb);
439
440	if (inode == NULL)
441		return NULL;
442
443	inode->i_mode = mode;
444	if (sb->s_root) {
445		inode->i_uid = d_inode(sb->s_root)->i_uid;
446		inode->i_gid = d_inode(sb->s_root)->i_gid;
447	}
448	simple_inode_init_ts(inode);
449	inode->i_ino = get_next_ino();
450
451	if (S_ISDIR(mode)) {
452		set_nlink(inode, 2);
453		inode->i_op = &autofs_dir_inode_operations;
454		inode->i_fop = &autofs_dir_operations;
455	} else if (S_ISLNK(mode)) {
456		inode->i_op = &autofs_symlink_inode_operations;
457	} else
458		WARN_ON(1);
459
460	return inode;
461}
462