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