1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * /proc/sys support
   4 */
   5#include <linux/init.h>
   6#include <linux/sysctl.h>
   7#include <linux/poll.h>
   8#include <linux/proc_fs.h>
   9#include <linux/printk.h>
  10#include <linux/security.h>
  11#include <linux/sched.h>
  12#include <linux/cred.h>
  13#include <linux/namei.h>
  14#include <linux/mm.h>
 
  15#include <linux/module.h>
 
 
 
  16#include "internal.h"
  17
 
 
 
 
  18static const struct dentry_operations proc_sys_dentry_operations;
  19static const struct file_operations proc_sys_file_operations;
  20static const struct inode_operations proc_sys_inode_operations;
  21static const struct file_operations proc_sys_dir_file_operations;
  22static const struct inode_operations proc_sys_dir_operations;
  23
  24/* Support for permanently empty directories */
  25
  26struct ctl_table sysctl_mount_point[] = {
  27	{ }
  28};
  29
  30static bool is_empty_dir(struct ctl_table_header *head)
  31{
  32	return head->ctl_table[0].child == sysctl_mount_point;
  33}
  34
  35static void set_empty_dir(struct ctl_dir *dir)
 
 
 
  36{
  37	dir->header.ctl_table[0].child = sysctl_mount_point;
  38}
 
  39
  40static void clear_empty_dir(struct ctl_dir *dir)
  41
  42{
  43	dir->header.ctl_table[0].child = NULL;
  44}
 
 
 
  45
  46void proc_sys_poll_notify(struct ctl_table_poll *poll)
  47{
  48	if (!poll)
  49		return;
  50
  51	atomic_inc(&poll->event);
  52	wake_up_interruptible(&poll->wait);
  53}
  54
  55static struct ctl_table root_table[] = {
  56	{
  57		.procname = "",
  58		.mode = S_IFDIR|S_IRUGO|S_IXUGO,
  59	},
  60	{ }
  61};
  62static struct ctl_table_root sysctl_table_root = {
  63	.default_set.dir.header = {
  64		{{.count = 1,
  65		  .nreg = 1,
  66		  .ctl_table = root_table }},
  67		.ctl_table_arg = root_table,
  68		.root = &sysctl_table_root,
  69		.set = &sysctl_table_root.default_set,
  70	},
  71};
  72
  73static DEFINE_SPINLOCK(sysctl_lock);
  74
  75static void drop_sysctl_table(struct ctl_table_header *header);
  76static int sysctl_follow_link(struct ctl_table_header **phead,
  77	struct ctl_table **pentry);
  78static int insert_links(struct ctl_table_header *head);
  79static void put_links(struct ctl_table_header *header);
  80
  81static void sysctl_print_dir(struct ctl_dir *dir)
  82{
  83	if (dir->header.parent)
  84		sysctl_print_dir(dir->header.parent);
  85	pr_cont("%s/", dir->header.ctl_table[0].procname);
  86}
  87
  88static int namecmp(const char *name1, int len1, const char *name2, int len2)
  89{
  90	int minlen;
  91	int cmp;
  92
  93	minlen = len1;
  94	if (minlen > len2)
  95		minlen = len2;
  96
  97	cmp = memcmp(name1, name2, minlen);
  98	if (cmp == 0)
  99		cmp = len1 - len2;
 100	return cmp;
 101}
 102
 103/* Called under sysctl_lock */
 104static struct ctl_table *find_entry(struct ctl_table_header **phead,
 105	struct ctl_dir *dir, const char *name, int namelen)
 106{
 107	struct ctl_table_header *head;
 108	struct ctl_table *entry;
 109	struct rb_node *node = dir->root.rb_node;
 110
 111	while (node)
 112	{
 113		struct ctl_node *ctl_node;
 114		const char *procname;
 115		int cmp;
 116
 117		ctl_node = rb_entry(node, struct ctl_node, node);
 118		head = ctl_node->header;
 119		entry = &head->ctl_table[ctl_node - head->node];
 120		procname = entry->procname;
 121
 122		cmp = namecmp(name, namelen, procname, strlen(procname));
 123		if (cmp < 0)
 124			node = node->rb_left;
 125		else if (cmp > 0)
 126			node = node->rb_right;
 127		else {
 128			*phead = head;
 129			return entry;
 130		}
 131	}
 132	return NULL;
 133}
 134
 135static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
 136{
 137	struct rb_node *node = &head->node[entry - head->ctl_table].node;
 138	struct rb_node **p = &head->parent->root.rb_node;
 139	struct rb_node *parent = NULL;
 140	const char *name = entry->procname;
 141	int namelen = strlen(name);
 142
 143	while (*p) {
 144		struct ctl_table_header *parent_head;
 145		struct ctl_table *parent_entry;
 146		struct ctl_node *parent_node;
 147		const char *parent_name;
 148		int cmp;
 149
 150		parent = *p;
 151		parent_node = rb_entry(parent, struct ctl_node, node);
 152		parent_head = parent_node->header;
 153		parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
 154		parent_name = parent_entry->procname;
 155
 156		cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
 157		if (cmp < 0)
 158			p = &(*p)->rb_left;
 159		else if (cmp > 0)
 160			p = &(*p)->rb_right;
 161		else {
 162			pr_err("sysctl duplicate entry: ");
 163			sysctl_print_dir(head->parent);
 164			pr_cont("/%s\n", entry->procname);
 165			return -EEXIST;
 166		}
 167	}
 168
 169	rb_link_node(node, parent, p);
 170	rb_insert_color(node, &head->parent->root);
 171	return 0;
 172}
 173
 174static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
 175{
 176	struct rb_node *node = &head->node[entry - head->ctl_table].node;
 177
 178	rb_erase(node, &head->parent->root);
 179}
 180
 181static void init_header(struct ctl_table_header *head,
 182	struct ctl_table_root *root, struct ctl_table_set *set,
 183	struct ctl_node *node, struct ctl_table *table)
 184{
 185	head->ctl_table = table;
 
 186	head->ctl_table_arg = table;
 187	head->used = 0;
 188	head->count = 1;
 189	head->nreg = 1;
 190	head->unregistering = NULL;
 191	head->root = root;
 192	head->set = set;
 193	head->parent = NULL;
 194	head->node = node;
 195	INIT_HLIST_HEAD(&head->inodes);
 196	if (node) {
 197		struct ctl_table *entry;
 198		for (entry = table; entry->procname; entry++, node++)
 
 199			node->header = head;
 
 
 200	}
 201}
 202
 203static void erase_header(struct ctl_table_header *head)
 204{
 205	struct ctl_table *entry;
 206	for (entry = head->ctl_table; entry->procname; entry++)
 
 207		erase_entry(head, entry);
 208}
 209
 210static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
 211{
 212	struct ctl_table *entry;
 
 213	int err;
 214
 
 215	/* Is this a permanently empty directory? */
 216	if (is_empty_dir(&dir->header))
 217		return -EROFS;
 218
 219	/* Am I creating a permanently empty directory? */
 220	if (header->ctl_table == sysctl_mount_point) {
 
 221		if (!RB_EMPTY_ROOT(&dir->root))
 222			return -EINVAL;
 223		set_empty_dir(dir);
 224	}
 225
 226	dir->header.nreg++;
 227	header->parent = dir;
 228	err = insert_links(header);
 229	if (err)
 230		goto fail_links;
 231	for (entry = header->ctl_table; entry->procname; entry++) {
 232		err = insert_entry(header, entry);
 233		if (err)
 234			goto fail;
 235	}
 236	return 0;
 237fail:
 238	erase_header(header);
 239	put_links(header);
 240fail_links:
 241	if (header->ctl_table == sysctl_mount_point)
 242		clear_empty_dir(dir);
 243	header->parent = NULL;
 244	drop_sysctl_table(&dir->header);
 245	return err;
 246}
 247
 248/* called under sysctl_lock */
 249static int use_table(struct ctl_table_header *p)
 250{
 251	if (unlikely(p->unregistering))
 252		return 0;
 253	p->used++;
 254	return 1;
 255}
 256
 257/* called under sysctl_lock */
 258static void unuse_table(struct ctl_table_header *p)
 259{
 260	if (!--p->used)
 261		if (unlikely(p->unregistering))
 262			complete(p->unregistering);
 263}
 264
 265static void proc_sys_prune_dcache(struct ctl_table_header *head)
 266{
 267	struct inode *inode;
 268	struct proc_inode *ei;
 269	struct hlist_node *node;
 270	struct super_block *sb;
 271
 272	rcu_read_lock();
 273	for (;;) {
 274		node = hlist_first_rcu(&head->inodes);
 275		if (!node)
 276			break;
 277		ei = hlist_entry(node, struct proc_inode, sysctl_inodes);
 278		spin_lock(&sysctl_lock);
 279		hlist_del_init_rcu(&ei->sysctl_inodes);
 280		spin_unlock(&sysctl_lock);
 281
 282		inode = &ei->vfs_inode;
 283		sb = inode->i_sb;
 284		if (!atomic_inc_not_zero(&sb->s_active))
 285			continue;
 286		inode = igrab(inode);
 287		rcu_read_unlock();
 288		if (unlikely(!inode)) {
 289			deactivate_super(sb);
 290			rcu_read_lock();
 291			continue;
 292		}
 293
 294		d_prune_aliases(inode);
 295		iput(inode);
 296		deactivate_super(sb);
 297
 298		rcu_read_lock();
 299	}
 300	rcu_read_unlock();
 301}
 302
 303/* called under sysctl_lock, will reacquire if has to wait */
 304static void start_unregistering(struct ctl_table_header *p)
 305{
 306	/*
 307	 * if p->used is 0, nobody will ever touch that entry again;
 308	 * we'll eliminate all paths to it before dropping sysctl_lock
 309	 */
 310	if (unlikely(p->used)) {
 311		struct completion wait;
 312		init_completion(&wait);
 313		p->unregistering = &wait;
 314		spin_unlock(&sysctl_lock);
 315		wait_for_completion(&wait);
 316	} else {
 317		/* anything non-NULL; we'll never dereference it */
 318		p->unregistering = ERR_PTR(-EINVAL);
 319		spin_unlock(&sysctl_lock);
 320	}
 321	/*
 322	 * Prune dentries for unregistered sysctls: namespaced sysctls
 323	 * can have duplicate names and contaminate dcache very badly.
 324	 */
 325	proc_sys_prune_dcache(p);
 326	/*
 327	 * do not remove from the list until nobody holds it; walking the
 328	 * list in do_sysctl() relies on that.
 329	 */
 330	spin_lock(&sysctl_lock);
 331	erase_header(p);
 332}
 333
 334static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
 335{
 336	BUG_ON(!head);
 337	spin_lock(&sysctl_lock);
 338	if (!use_table(head))
 339		head = ERR_PTR(-ENOENT);
 340	spin_unlock(&sysctl_lock);
 341	return head;
 342}
 343
 344static void sysctl_head_finish(struct ctl_table_header *head)
 345{
 346	if (!head)
 347		return;
 348	spin_lock(&sysctl_lock);
 349	unuse_table(head);
 350	spin_unlock(&sysctl_lock);
 351}
 352
 353static struct ctl_table_set *
 354lookup_header_set(struct ctl_table_root *root)
 355{
 356	struct ctl_table_set *set = &root->default_set;
 357	if (root->lookup)
 358		set = root->lookup(root);
 359	return set;
 360}
 361
 362static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
 363				      struct ctl_dir *dir,
 364				      const char *name, int namelen)
 365{
 366	struct ctl_table_header *head;
 367	struct ctl_table *entry;
 368
 369	spin_lock(&sysctl_lock);
 370	entry = find_entry(&head, dir, name, namelen);
 371	if (entry && use_table(head))
 372		*phead = head;
 373	else
 374		entry = NULL;
 375	spin_unlock(&sysctl_lock);
 376	return entry;
 377}
 378
 379static struct ctl_node *first_usable_entry(struct rb_node *node)
 380{
 381	struct ctl_node *ctl_node;
 382
 383	for (;node; node = rb_next(node)) {
 384		ctl_node = rb_entry(node, struct ctl_node, node);
 385		if (use_table(ctl_node->header))
 386			return ctl_node;
 387	}
 388	return NULL;
 389}
 390
 391static void first_entry(struct ctl_dir *dir,
 392	struct ctl_table_header **phead, struct ctl_table **pentry)
 393{
 394	struct ctl_table_header *head = NULL;
 395	struct ctl_table *entry = NULL;
 396	struct ctl_node *ctl_node;
 397
 398	spin_lock(&sysctl_lock);
 399	ctl_node = first_usable_entry(rb_first(&dir->root));
 400	spin_unlock(&sysctl_lock);
 401	if (ctl_node) {
 402		head = ctl_node->header;
 403		entry = &head->ctl_table[ctl_node - head->node];
 404	}
 405	*phead = head;
 406	*pentry = entry;
 407}
 408
 409static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
 410{
 411	struct ctl_table_header *head = *phead;
 412	struct ctl_table *entry = *pentry;
 413	struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
 414
 415	spin_lock(&sysctl_lock);
 416	unuse_table(head);
 417
 418	ctl_node = first_usable_entry(rb_next(&ctl_node->node));
 419	spin_unlock(&sysctl_lock);
 420	head = NULL;
 421	if (ctl_node) {
 422		head = ctl_node->header;
 423		entry = &head->ctl_table[ctl_node - head->node];
 424	}
 425	*phead = head;
 426	*pentry = entry;
 427}
 428
 429/*
 430 * sysctl_perm does NOT grant the superuser all rights automatically, because
 431 * some sysctl variables are readonly even to root.
 432 */
 433
 434static int test_perm(int mode, int op)
 435{
 436	if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
 437		mode >>= 6;
 438	else if (in_egroup_p(GLOBAL_ROOT_GID))
 439		mode >>= 3;
 440	if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
 441		return 0;
 442	return -EACCES;
 443}
 444
 445static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
 446{
 447	struct ctl_table_root *root = head->root;
 448	int mode;
 449
 450	if (root->permissions)
 451		mode = root->permissions(head, table);
 452	else
 453		mode = table->mode;
 454
 455	return test_perm(mode, op);
 456}
 457
 458static struct inode *proc_sys_make_inode(struct super_block *sb,
 459		struct ctl_table_header *head, struct ctl_table *table)
 460{
 461	struct ctl_table_root *root = head->root;
 462	struct inode *inode;
 463	struct proc_inode *ei;
 464
 465	inode = new_inode(sb);
 466	if (!inode)
 467		goto out;
 468
 469	inode->i_ino = get_next_ino();
 470
 471	ei = PROC_I(inode);
 472
 473	spin_lock(&sysctl_lock);
 474	if (unlikely(head->unregistering)) {
 475		spin_unlock(&sysctl_lock);
 476		iput(inode);
 477		inode = NULL;
 478		goto out;
 479	}
 480	ei->sysctl = head;
 481	ei->sysctl_entry = table;
 482	hlist_add_head_rcu(&ei->sysctl_inodes, &head->inodes);
 483	head->count++;
 484	spin_unlock(&sysctl_lock);
 485
 486	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 487	inode->i_mode = table->mode;
 488	if (!S_ISDIR(table->mode)) {
 489		inode->i_mode |= S_IFREG;
 490		inode->i_op = &proc_sys_inode_operations;
 491		inode->i_fop = &proc_sys_file_operations;
 492	} else {
 493		inode->i_mode |= S_IFDIR;
 494		inode->i_op = &proc_sys_dir_operations;
 495		inode->i_fop = &proc_sys_dir_file_operations;
 496		if (is_empty_dir(head))
 497			make_empty_dir_inode(inode);
 498	}
 499
 500	if (root->set_ownership)
 501		root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
 
 
 
 
 502
 503out:
 504	return inode;
 505}
 506
 507void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
 508{
 509	spin_lock(&sysctl_lock);
 510	hlist_del_init_rcu(&PROC_I(inode)->sysctl_inodes);
 511	if (!--head->count)
 512		kfree_rcu(head, rcu);
 513	spin_unlock(&sysctl_lock);
 514}
 515
 516static struct ctl_table_header *grab_header(struct inode *inode)
 517{
 518	struct ctl_table_header *head = PROC_I(inode)->sysctl;
 519	if (!head)
 520		head = &sysctl_table_root.default_set.dir.header;
 521	return sysctl_head_grab(head);
 522}
 523
 524static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
 525					unsigned int flags)
 526{
 527	struct ctl_table_header *head = grab_header(dir);
 528	struct ctl_table_header *h = NULL;
 529	const struct qstr *name = &dentry->d_name;
 530	struct ctl_table *p;
 531	struct inode *inode;
 532	struct dentry *err = ERR_PTR(-ENOENT);
 533	struct ctl_dir *ctl_dir;
 534	int ret;
 535
 536	if (IS_ERR(head))
 537		return ERR_CAST(head);
 538
 539	ctl_dir = container_of(head, struct ctl_dir, header);
 540
 541	p = lookup_entry(&h, ctl_dir, name->name, name->len);
 542	if (!p)
 543		goto out;
 544
 545	if (S_ISLNK(p->mode)) {
 546		ret = sysctl_follow_link(&h, &p);
 547		err = ERR_PTR(ret);
 548		if (ret)
 549			goto out;
 550	}
 551
 552	err = ERR_PTR(-ENOMEM);
 553	inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
 554	if (!inode)
 555		goto out;
 556
 557	err = NULL;
 558	d_set_d_op(dentry, &proc_sys_dentry_operations);
 559	d_add(dentry, inode);
 
 560
 561out:
 562	if (h)
 563		sysctl_head_finish(h);
 564	sysctl_head_finish(head);
 565	return err;
 566}
 567
 568static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
 569		size_t count, loff_t *ppos, int write)
 570{
 571	struct inode *inode = file_inode(filp);
 572	struct ctl_table_header *head = grab_header(inode);
 573	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
 
 
 574	ssize_t error;
 575	size_t res;
 576
 577	if (IS_ERR(head))
 578		return PTR_ERR(head);
 579
 580	/*
 581	 * At this point we know that the sysctl was not unregistered
 582	 * and won't be until we finish.
 583	 */
 584	error = -EPERM;
 585	if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
 586		goto out;
 587
 588	/* if that can happen at all, it should be -EINVAL, not -EISDIR */
 589	error = -EINVAL;
 590	if (!table->proc_handler)
 591		goto out;
 592
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 593	/* careful: calling conventions are nasty here */
 594	res = count;
 595	error = table->proc_handler(table, write, buf, &res, ppos);
 596	if (!error)
 597		error = res;
 
 
 
 
 
 
 
 
 
 598out:
 599	sysctl_head_finish(head);
 600
 601	return error;
 602}
 603
 604static ssize_t proc_sys_read(struct file *filp, char __user *buf,
 605				size_t count, loff_t *ppos)
 606{
 607	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
 608}
 609
 610static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
 611				size_t count, loff_t *ppos)
 612{
 613	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
 614}
 615
 616static int proc_sys_open(struct inode *inode, struct file *filp)
 617{
 618	struct ctl_table_header *head = grab_header(inode);
 619	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
 620
 621	/* sysctl was unregistered */
 622	if (IS_ERR(head))
 623		return PTR_ERR(head);
 624
 625	if (table->poll)
 626		filp->private_data = proc_sys_poll_event(table->poll);
 627
 628	sysctl_head_finish(head);
 629
 630	return 0;
 631}
 632
 633static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
 634{
 635	struct inode *inode = file_inode(filp);
 636	struct ctl_table_header *head = grab_header(inode);
 637	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
 638	__poll_t ret = DEFAULT_POLLMASK;
 639	unsigned long event;
 640
 641	/* sysctl was unregistered */
 642	if (IS_ERR(head))
 643		return EPOLLERR | EPOLLHUP;
 644
 645	if (!table->proc_handler)
 646		goto out;
 647
 648	if (!table->poll)
 649		goto out;
 650
 651	event = (unsigned long)filp->private_data;
 652	poll_wait(filp, &table->poll->wait, wait);
 653
 654	if (event != atomic_read(&table->poll->event)) {
 655		filp->private_data = proc_sys_poll_event(table->poll);
 656		ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
 657	}
 658
 659out:
 660	sysctl_head_finish(head);
 661
 662	return ret;
 663}
 664
 665static bool proc_sys_fill_cache(struct file *file,
 666				struct dir_context *ctx,
 667				struct ctl_table_header *head,
 668				struct ctl_table *table)
 669{
 670	struct dentry *child, *dir = file->f_path.dentry;
 671	struct inode *inode;
 672	struct qstr qname;
 673	ino_t ino = 0;
 674	unsigned type = DT_UNKNOWN;
 675
 676	qname.name = table->procname;
 677	qname.len  = strlen(table->procname);
 678	qname.hash = full_name_hash(dir, qname.name, qname.len);
 679
 680	child = d_lookup(dir, &qname);
 681	if (!child) {
 682		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 683		child = d_alloc_parallel(dir, &qname, &wq);
 684		if (IS_ERR(child))
 685			return false;
 686		if (d_in_lookup(child)) {
 
 
 687			inode = proc_sys_make_inode(dir->d_sb, head, table);
 688			if (!inode) {
 689				d_lookup_done(child);
 
 
 
 
 
 690				dput(child);
 691				return false;
 692			}
 693			d_set_d_op(child, &proc_sys_dentry_operations);
 694			d_add(child, inode);
 695		}
 696	}
 697	inode = d_inode(child);
 698	ino  = inode->i_ino;
 699	type = inode->i_mode >> 12;
 700	dput(child);
 701	return dir_emit(ctx, qname.name, qname.len, ino, type);
 702}
 703
 704static bool proc_sys_link_fill_cache(struct file *file,
 705				    struct dir_context *ctx,
 706				    struct ctl_table_header *head,
 707				    struct ctl_table *table)
 708{
 709	bool ret = true;
 710
 711	head = sysctl_head_grab(head);
 712	if (IS_ERR(head))
 713		return false;
 714
 715	/* It is not an error if we can not follow the link ignore it */
 716	if (sysctl_follow_link(&head, &table))
 717		goto out;
 718
 719	ret = proc_sys_fill_cache(file, ctx, head, table);
 720out:
 721	sysctl_head_finish(head);
 722	return ret;
 723}
 724
 725static int scan(struct ctl_table_header *head, struct ctl_table *table,
 726		unsigned long *pos, struct file *file,
 727		struct dir_context *ctx)
 728{
 729	bool res;
 730
 731	if ((*pos)++ < ctx->pos)
 732		return true;
 733
 734	if (unlikely(S_ISLNK(table->mode)))
 735		res = proc_sys_link_fill_cache(file, ctx, head, table);
 736	else
 737		res = proc_sys_fill_cache(file, ctx, head, table);
 738
 739	if (res)
 740		ctx->pos = *pos;
 741
 742	return res;
 743}
 744
 745static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
 746{
 747	struct ctl_table_header *head = grab_header(file_inode(file));
 748	struct ctl_table_header *h = NULL;
 749	struct ctl_table *entry;
 750	struct ctl_dir *ctl_dir;
 751	unsigned long pos;
 752
 753	if (IS_ERR(head))
 754		return PTR_ERR(head);
 755
 756	ctl_dir = container_of(head, struct ctl_dir, header);
 757
 758	if (!dir_emit_dots(file, ctx))
 759		goto out;
 760
 761	pos = 2;
 762
 763	for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
 764		if (!scan(h, entry, &pos, file, ctx)) {
 765			sysctl_head_finish(h);
 766			break;
 767		}
 768	}
 769out:
 770	sysctl_head_finish(head);
 771	return 0;
 772}
 773
 774static int proc_sys_permission(struct inode *inode, int mask)
 
 775{
 776	/*
 777	 * sysctl entries that are not writeable,
 778	 * are _NOT_ writeable, capabilities or not.
 779	 */
 780	struct ctl_table_header *head;
 781	struct ctl_table *table;
 782	int error;
 783
 784	/* Executable files are not allowed under /proc/sys/ */
 785	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
 786		return -EACCES;
 787
 788	head = grab_header(inode);
 789	if (IS_ERR(head))
 790		return PTR_ERR(head);
 791
 792	table = PROC_I(inode)->sysctl_entry;
 793	if (!table) /* global root - r-xr-xr-x */
 794		error = mask & MAY_WRITE ? -EACCES : 0;
 795	else /* Use the permissions on the sysctl table entry */
 796		error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
 797
 798	sysctl_head_finish(head);
 799	return error;
 800}
 801
 802static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
 
 803{
 804	struct inode *inode = d_inode(dentry);
 805	int error;
 806
 807	if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
 808		return -EPERM;
 809
 810	error = setattr_prepare(dentry, attr);
 811	if (error)
 812		return error;
 813
 814	setattr_copy(inode, attr);
 815	mark_inode_dirty(inode);
 816	return 0;
 817}
 818
 819static int proc_sys_getattr(const struct path *path, struct kstat *stat,
 
 820			    u32 request_mask, unsigned int query_flags)
 821{
 822	struct inode *inode = d_inode(path->dentry);
 823	struct ctl_table_header *head = grab_header(inode);
 824	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
 825
 826	if (IS_ERR(head))
 827		return PTR_ERR(head);
 828
 829	generic_fillattr(inode, stat);
 830	if (table)
 831		stat->mode = (stat->mode & S_IFMT) | table->mode;
 832
 833	sysctl_head_finish(head);
 834	return 0;
 835}
 836
 837static const struct file_operations proc_sys_file_operations = {
 838	.open		= proc_sys_open,
 839	.poll		= proc_sys_poll,
 840	.read		= proc_sys_read,
 841	.write		= proc_sys_write,
 
 
 842	.llseek		= default_llseek,
 843};
 844
 845static const struct file_operations proc_sys_dir_file_operations = {
 846	.read		= generic_read_dir,
 847	.iterate_shared	= proc_sys_readdir,
 848	.llseek		= generic_file_llseek,
 849};
 850
 851static const struct inode_operations proc_sys_inode_operations = {
 852	.permission	= proc_sys_permission,
 853	.setattr	= proc_sys_setattr,
 854	.getattr	= proc_sys_getattr,
 855};
 856
 857static const struct inode_operations proc_sys_dir_operations = {
 858	.lookup		= proc_sys_lookup,
 859	.permission	= proc_sys_permission,
 860	.setattr	= proc_sys_setattr,
 861	.getattr	= proc_sys_getattr,
 862};
 863
 864static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
 865{
 866	if (flags & LOOKUP_RCU)
 867		return -ECHILD;
 868	return !PROC_I(d_inode(dentry))->sysctl->unregistering;
 869}
 870
 871static int proc_sys_delete(const struct dentry *dentry)
 872{
 873	return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
 874}
 875
 876static int sysctl_is_seen(struct ctl_table_header *p)
 877{
 878	struct ctl_table_set *set = p->set;
 879	int res;
 880	spin_lock(&sysctl_lock);
 881	if (p->unregistering)
 882		res = 0;
 883	else if (!set->is_seen)
 884		res = 1;
 885	else
 886		res = set->is_seen(set);
 887	spin_unlock(&sysctl_lock);
 888	return res;
 889}
 890
 891static int proc_sys_compare(const struct dentry *dentry,
 892		unsigned int len, const char *str, const struct qstr *name)
 893{
 894	struct ctl_table_header *head;
 895	struct inode *inode;
 896
 897	/* Although proc doesn't have negative dentries, rcu-walk means
 898	 * that inode here can be NULL */
 899	/* AV: can it, indeed? */
 900	inode = d_inode_rcu(dentry);
 901	if (!inode)
 902		return 1;
 903	if (name->len != len)
 904		return 1;
 905	if (memcmp(name->name, str, len))
 906		return 1;
 907	head = rcu_dereference(PROC_I(inode)->sysctl);
 908	return !head || !sysctl_is_seen(head);
 909}
 910
 911static const struct dentry_operations proc_sys_dentry_operations = {
 912	.d_revalidate	= proc_sys_revalidate,
 913	.d_delete	= proc_sys_delete,
 914	.d_compare	= proc_sys_compare,
 915};
 916
 917static struct ctl_dir *find_subdir(struct ctl_dir *dir,
 918				   const char *name, int namelen)
 919{
 920	struct ctl_table_header *head;
 921	struct ctl_table *entry;
 922
 923	entry = find_entry(&head, dir, name, namelen);
 924	if (!entry)
 925		return ERR_PTR(-ENOENT);
 926	if (!S_ISDIR(entry->mode))
 927		return ERR_PTR(-ENOTDIR);
 928	return container_of(head, struct ctl_dir, header);
 929}
 930
 931static struct ctl_dir *new_dir(struct ctl_table_set *set,
 932			       const char *name, int namelen)
 933{
 934	struct ctl_table *table;
 935	struct ctl_dir *new;
 936	struct ctl_node *node;
 937	char *new_name;
 938
 939	new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
 940		      sizeof(struct ctl_table)*2 +  namelen + 1,
 941		      GFP_KERNEL);
 942	if (!new)
 943		return NULL;
 944
 945	node = (struct ctl_node *)(new + 1);
 946	table = (struct ctl_table *)(node + 1);
 947	new_name = (char *)(table + 2);
 948	memcpy(new_name, name, namelen);
 949	new_name[namelen] = '\0';
 950	table[0].procname = new_name;
 951	table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
 952	init_header(&new->header, set->dir.header.root, set, node, table);
 953
 954	return new;
 955}
 956
 957/**
 958 * get_subdir - find or create a subdir with the specified name.
 959 * @dir:  Directory to create the subdirectory in
 960 * @name: The name of the subdirectory to find or create
 961 * @namelen: The length of name
 962 *
 963 * Takes a directory with an elevated reference count so we know that
 964 * if we drop the lock the directory will not go away.  Upon success
 965 * the reference is moved from @dir to the returned subdirectory.
 966 * Upon error an error code is returned and the reference on @dir is
 967 * simply dropped.
 968 */
 969static struct ctl_dir *get_subdir(struct ctl_dir *dir,
 970				  const char *name, int namelen)
 971{
 972	struct ctl_table_set *set = dir->header.set;
 973	struct ctl_dir *subdir, *new = NULL;
 974	int err;
 975
 976	spin_lock(&sysctl_lock);
 977	subdir = find_subdir(dir, name, namelen);
 978	if (!IS_ERR(subdir))
 979		goto found;
 980	if (PTR_ERR(subdir) != -ENOENT)
 981		goto failed;
 982
 983	spin_unlock(&sysctl_lock);
 984	new = new_dir(set, name, namelen);
 985	spin_lock(&sysctl_lock);
 986	subdir = ERR_PTR(-ENOMEM);
 987	if (!new)
 988		goto failed;
 989
 990	/* Was the subdir added while we dropped the lock? */
 991	subdir = find_subdir(dir, name, namelen);
 992	if (!IS_ERR(subdir))
 993		goto found;
 994	if (PTR_ERR(subdir) != -ENOENT)
 995		goto failed;
 996
 997	/* Nope.  Use the our freshly made directory entry. */
 998	err = insert_header(dir, &new->header);
 999	subdir = ERR_PTR(err);
1000	if (err)
1001		goto failed;
1002	subdir = new;
1003found:
1004	subdir->header.nreg++;
1005failed:
1006	if (IS_ERR(subdir)) {
1007		pr_err("sysctl could not get directory: ");
1008		sysctl_print_dir(dir);
1009		pr_cont("/%*.*s %ld\n",
1010			namelen, namelen, name, PTR_ERR(subdir));
1011	}
1012	drop_sysctl_table(&dir->header);
1013	if (new)
1014		drop_sysctl_table(&new->header);
1015	spin_unlock(&sysctl_lock);
1016	return subdir;
1017}
1018
1019static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
1020{
1021	struct ctl_dir *parent;
1022	const char *procname;
1023	if (!dir->header.parent)
1024		return &set->dir;
1025	parent = xlate_dir(set, dir->header.parent);
1026	if (IS_ERR(parent))
1027		return parent;
1028	procname = dir->header.ctl_table[0].procname;
1029	return find_subdir(parent, procname, strlen(procname));
1030}
1031
1032static int sysctl_follow_link(struct ctl_table_header **phead,
1033	struct ctl_table **pentry)
1034{
1035	struct ctl_table_header *head;
1036	struct ctl_table_root *root;
1037	struct ctl_table_set *set;
1038	struct ctl_table *entry;
1039	struct ctl_dir *dir;
1040	int ret;
1041
1042	ret = 0;
1043	spin_lock(&sysctl_lock);
1044	root = (*pentry)->data;
1045	set = lookup_header_set(root);
1046	dir = xlate_dir(set, (*phead)->parent);
1047	if (IS_ERR(dir))
1048		ret = PTR_ERR(dir);
1049	else {
1050		const char *procname = (*pentry)->procname;
1051		head = NULL;
1052		entry = find_entry(&head, dir, procname, strlen(procname));
1053		ret = -ENOENT;
1054		if (entry && use_table(head)) {
1055			unuse_table(*phead);
1056			*phead = head;
1057			*pentry = entry;
1058			ret = 0;
1059		}
1060	}
1061
1062	spin_unlock(&sysctl_lock);
1063	return ret;
1064}
1065
1066static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
1067{
1068	struct va_format vaf;
1069	va_list args;
1070
1071	va_start(args, fmt);
1072	vaf.fmt = fmt;
1073	vaf.va = &args;
1074
1075	pr_err("sysctl table check failed: %s/%s %pV\n",
1076	       path, table->procname, &vaf);
1077
1078	va_end(args);
1079	return -EINVAL;
1080}
1081
1082static int sysctl_check_table_array(const char *path, struct ctl_table *table)
1083{
1084	int err = 0;
1085
1086	if ((table->proc_handler == proc_douintvec) ||
1087	    (table->proc_handler == proc_douintvec_minmax)) {
1088		if (table->maxlen != sizeof(unsigned int))
1089			err |= sysctl_err(path, table, "array not allowed");
1090	}
1091
 
 
 
 
 
 
 
 
 
 
1092	return err;
1093}
1094
1095static int sysctl_check_table(const char *path, struct ctl_table *table)
1096{
 
1097	int err = 0;
1098	for (; table->procname; table++) {
1099		if (table->child)
1100			err |= sysctl_err(path, table, "Not a file");
1101
1102		if ((table->proc_handler == proc_dostring) ||
1103		    (table->proc_handler == proc_dointvec) ||
1104		    (table->proc_handler == proc_douintvec) ||
1105		    (table->proc_handler == proc_douintvec_minmax) ||
1106		    (table->proc_handler == proc_dointvec_minmax) ||
1107		    (table->proc_handler == proc_dointvec_jiffies) ||
1108		    (table->proc_handler == proc_dointvec_userhz_jiffies) ||
1109		    (table->proc_handler == proc_dointvec_ms_jiffies) ||
1110		    (table->proc_handler == proc_doulongvec_minmax) ||
1111		    (table->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
1112			if (!table->data)
1113				err |= sysctl_err(path, table, "No data");
1114			if (!table->maxlen)
1115				err |= sysctl_err(path, table, "No maxlen");
1116			else
1117				err |= sysctl_check_table_array(path, table);
1118		}
1119		if (!table->proc_handler)
1120			err |= sysctl_err(path, table, "No proc_handler");
1121
1122		if ((table->mode & (S_IRUGO|S_IWUGO)) != table->mode)
1123			err |= sysctl_err(path, table, "bogus .mode 0%o",
1124				table->mode);
1125	}
1126	return err;
1127}
1128
1129static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
1130	struct ctl_table_root *link_root)
1131{
1132	struct ctl_table *link_table, *entry, *link;
1133	struct ctl_table_header *links;
1134	struct ctl_node *node;
1135	char *link_name;
1136	int nr_entries, name_bytes;
1137
1138	name_bytes = 0;
1139	nr_entries = 0;
1140	for (entry = table; entry->procname; entry++) {
1141		nr_entries++;
1142		name_bytes += strlen(entry->procname) + 1;
1143	}
1144
1145	links = kzalloc(sizeof(struct ctl_table_header) +
1146			sizeof(struct ctl_node)*nr_entries +
1147			sizeof(struct ctl_table)*(nr_entries + 1) +
1148			name_bytes,
1149			GFP_KERNEL);
1150
1151	if (!links)
1152		return NULL;
1153
1154	node = (struct ctl_node *)(links + 1);
1155	link_table = (struct ctl_table *)(node + nr_entries);
1156	link_name = (char *)&link_table[nr_entries + 1];
 
1157
1158	for (link = link_table, entry = table; entry->procname; link++, entry++) {
1159		int len = strlen(entry->procname) + 1;
1160		memcpy(link_name, entry->procname, len);
1161		link->procname = link_name;
1162		link->mode = S_IFLNK|S_IRWXUGO;
1163		link->data = link_root;
1164		link_name += len;
 
1165	}
1166	init_header(links, dir->header.root, dir->header.set, node, link_table);
 
1167	links->nreg = nr_entries;
1168
1169	return links;
1170}
1171
1172static bool get_links(struct ctl_dir *dir,
1173	struct ctl_table *table, struct ctl_table_root *link_root)
 
1174{
1175	struct ctl_table_header *head;
1176	struct ctl_table *entry, *link;
1177
 
 
 
 
1178	/* Are there links available for every entry in table? */
1179	for (entry = table; entry->procname; entry++) {
1180		const char *procname = entry->procname;
1181		link = find_entry(&head, dir, procname, strlen(procname));
1182		if (!link)
1183			return false;
1184		if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
1185			continue;
1186		if (S_ISLNK(link->mode) && (link->data == link_root))
1187			continue;
1188		return false;
1189	}
1190
1191	/* The checks passed.  Increase the registration count on the links */
1192	for (entry = table; entry->procname; entry++) {
1193		const char *procname = entry->procname;
1194		link = find_entry(&head, dir, procname, strlen(procname));
1195		head->nreg++;
1196	}
1197	return true;
1198}
1199
1200static int insert_links(struct ctl_table_header *head)
1201{
1202	struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1203	struct ctl_dir *core_parent = NULL;
1204	struct ctl_table_header *links;
1205	int err;
1206
1207	if (head->set == root_set)
1208		return 0;
1209
1210	core_parent = xlate_dir(root_set, head->parent);
1211	if (IS_ERR(core_parent))
1212		return 0;
1213
1214	if (get_links(core_parent, head->ctl_table, head->root))
1215		return 0;
1216
1217	core_parent->header.nreg++;
1218	spin_unlock(&sysctl_lock);
1219
1220	links = new_links(core_parent, head->ctl_table, head->root);
1221
1222	spin_lock(&sysctl_lock);
1223	err = -ENOMEM;
1224	if (!links)
1225		goto out;
1226
1227	err = 0;
1228	if (get_links(core_parent, head->ctl_table, head->root)) {
1229		kfree(links);
1230		goto out;
1231	}
1232
1233	err = insert_header(core_parent, links);
1234	if (err)
1235		kfree(links);
1236out:
1237	drop_sysctl_table(&core_parent->header);
1238	return err;
1239}
1240
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1241/**
1242 * __register_sysctl_table - register a leaf sysctl table
1243 * @set: Sysctl tree to register on
1244 * @path: The path to the directory the sysctl table is in.
1245 * @table: the top-level table structure
 
 
 
 
1246 *
1247 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1248 * array. A completely 0 filled entry terminates the table.
1249 *
1250 * The members of the &struct ctl_table structure are used as follows:
1251 *
1252 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1253 *            enter a sysctl file
1254 *
1255 * data - a pointer to data for use by proc_handler
1256 *
1257 * maxlen - the maximum size in bytes of the data
1258 *
1259 * mode - the file permissions for the /proc/sys file
1260 *
1261 * child - must be %NULL.
1262 *
1263 * proc_handler - the text handler routine (described below)
1264 *
1265 * extra1, extra2 - extra pointers usable by the proc handler routines
 
 
1266 *
1267 * Leaf nodes in the sysctl tree will be represented by a single file
1268 * under /proc; non-leaf nodes will be represented by directories.
 
1269 *
1270 * There must be a proc_handler routine for any terminal nodes.
1271 * Several default handlers are available to cover common cases -
1272 *
1273 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1274 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1275 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1276 *
1277 * It is the handler's job to read the input buffer from user memory
1278 * and process it. The handler should return 0 on success.
1279 *
1280 * This routine returns %NULL on a failure to register, and a pointer
1281 * to the table header on success.
1282 */
1283struct ctl_table_header *__register_sysctl_table(
1284	struct ctl_table_set *set,
1285	const char *path, struct ctl_table *table)
1286{
1287	struct ctl_table_root *root = set->dir.header.root;
1288	struct ctl_table_header *header;
1289	const char *name, *nextname;
1290	struct ctl_dir *dir;
1291	struct ctl_table *entry;
1292	struct ctl_node *node;
1293	int nr_entries = 0;
1294
1295	for (entry = table; entry->procname; entry++)
1296		nr_entries++;
1297
1298	header = kzalloc(sizeof(struct ctl_table_header) +
1299			 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL);
1300	if (!header)
1301		return NULL;
1302
1303	node = (struct ctl_node *)(header + 1);
1304	init_header(header, root, set, node, table);
1305	if (sysctl_check_table(path, table))
1306		goto fail;
1307
1308	spin_lock(&sysctl_lock);
1309	dir = &set->dir;
1310	/* Reference moved down the diretory tree get_subdir */
1311	dir->header.nreg++;
1312	spin_unlock(&sysctl_lock);
1313
1314	/* Find the directory for the ctl_table */
1315	for (name = path; name; name = nextname) {
1316		int namelen;
1317		nextname = strchr(name, '/');
1318		if (nextname) {
1319			namelen = nextname - name;
1320			nextname++;
1321		} else {
1322			namelen = strlen(name);
1323		}
1324		if (namelen == 0)
1325			continue;
1326
1327		dir = get_subdir(dir, name, namelen);
1328		if (IS_ERR(dir))
1329			goto fail;
1330	}
1331
1332	spin_lock(&sysctl_lock);
1333	if (insert_header(dir, header))
1334		goto fail_put_dir_locked;
1335
1336	drop_sysctl_table(&dir->header);
1337	spin_unlock(&sysctl_lock);
1338
1339	return header;
1340
1341fail_put_dir_locked:
1342	drop_sysctl_table(&dir->header);
1343	spin_unlock(&sysctl_lock);
1344fail:
1345	kfree(header);
1346	dump_stack();
1347	return NULL;
1348}
1349
1350/**
1351 * register_sysctl - register a sysctl table
1352 * @path: The path to the directory the sysctl table is in.
1353 * @table: the table structure
 
 
 
 
 
 
 
 
1354 *
1355 * Register a sysctl table. @table should be a filled in ctl_table
1356 * array. A completely 0 filled entry terminates the table.
1357 *
1358 * See __register_sysctl_table for more details.
1359 */
1360struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
 
1361{
1362	return __register_sysctl_table(&sysctl_table_root.default_set,
1363					path, table);
1364}
1365EXPORT_SYMBOL(register_sysctl);
1366
1367static char *append_path(const char *path, char *pos, const char *name)
1368{
1369	int namelen;
1370	namelen = strlen(name);
1371	if (((pos - path) + namelen + 2) >= PATH_MAX)
1372		return NULL;
1373	memcpy(pos, name, namelen);
1374	pos[namelen] = '/';
1375	pos[namelen + 1] = '\0';
1376	pos += namelen + 1;
1377	return pos;
1378}
1379
1380static int count_subheaders(struct ctl_table *table)
1381{
1382	int has_files = 0;
1383	int nr_subheaders = 0;
1384	struct ctl_table *entry;
1385
1386	/* special case: no directory and empty directory */
1387	if (!table || !table->procname)
1388		return 1;
1389
1390	for (entry = table; entry->procname; entry++) {
1391		if (entry->child)
1392			nr_subheaders += count_subheaders(entry->child);
1393		else
1394			has_files = 1;
1395	}
1396	return nr_subheaders + has_files;
1397}
1398
1399static int register_leaf_sysctl_tables(const char *path, char *pos,
1400	struct ctl_table_header ***subheader, struct ctl_table_set *set,
1401	struct ctl_table *table)
1402{
1403	struct ctl_table *ctl_table_arg = NULL;
1404	struct ctl_table *entry, *files;
1405	int nr_files = 0;
1406	int nr_dirs = 0;
1407	int err = -ENOMEM;
1408
1409	for (entry = table; entry->procname; entry++) {
1410		if (entry->child)
1411			nr_dirs++;
1412		else
1413			nr_files++;
1414	}
1415
1416	files = table;
1417	/* If there are mixed files and directories we need a new table */
1418	if (nr_dirs && nr_files) {
1419		struct ctl_table *new;
1420		files = kzalloc(sizeof(struct ctl_table) * (nr_files + 1),
1421				GFP_KERNEL);
1422		if (!files)
1423			goto out;
1424
1425		ctl_table_arg = files;
1426		for (new = files, entry = table; entry->procname; entry++) {
1427			if (entry->child)
1428				continue;
1429			*new = *entry;
1430			new++;
1431		}
1432	}
1433
1434	/* Register everything except a directory full of subdirectories */
1435	if (nr_files || !nr_dirs) {
1436		struct ctl_table_header *header;
1437		header = __register_sysctl_table(set, path, files);
1438		if (!header) {
1439			kfree(ctl_table_arg);
1440			goto out;
1441		}
1442
1443		/* Remember if we need to free the file table */
1444		header->ctl_table_arg = ctl_table_arg;
1445		**subheader = header;
1446		(*subheader)++;
1447	}
1448
1449	/* Recurse into the subdirectories. */
1450	for (entry = table; entry->procname; entry++) {
1451		char *child_pos;
1452
1453		if (!entry->child)
1454			continue;
1455
1456		err = -ENAMETOOLONG;
1457		child_pos = append_path(path, pos, entry->procname);
1458		if (!child_pos)
1459			goto out;
1460
1461		err = register_leaf_sysctl_tables(path, child_pos, subheader,
1462						  set, entry->child);
1463		pos[0] = '\0';
1464		if (err)
1465			goto out;
1466	}
1467	err = 0;
1468out:
1469	/* On failure our caller will unregister all registered subheaders */
1470	return err;
1471}
 
1472
1473/**
1474 * __register_sysctl_paths - register a sysctl table hierarchy
1475 * @set: Sysctl tree to register on
1476 * @path: The path to the directory the sysctl table is in.
1477 * @table: the top-level table structure
1478 *
1479 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1480 * array. A completely 0 filled entry terminates the table.
 
 
 
 
 
 
 
 
 
 
1481 *
1482 * See __register_sysctl_table for more details.
1483 */
1484struct ctl_table_header *__register_sysctl_paths(
1485	struct ctl_table_set *set,
1486	const struct ctl_path *path, struct ctl_table *table)
1487{
1488	struct ctl_table *ctl_table_arg = table;
1489	int nr_subheaders = count_subheaders(table);
1490	struct ctl_table_header *header = NULL, **subheaders, **subheader;
1491	const struct ctl_path *component;
1492	char *new_path, *pos;
1493
1494	pos = new_path = kmalloc(PATH_MAX, GFP_KERNEL);
1495	if (!new_path)
1496		return NULL;
1497
1498	pos[0] = '\0';
1499	for (component = path; component->procname; component++) {
1500		pos = append_path(new_path, pos, component->procname);
1501		if (!pos)
1502			goto out;
1503	}
1504	while (table->procname && table->child && !table[1].procname) {
1505		pos = append_path(new_path, pos, table->procname);
1506		if (!pos)
1507			goto out;
1508		table = table->child;
1509	}
1510	if (nr_subheaders == 1) {
1511		header = __register_sysctl_table(set, new_path, table);
1512		if (header)
1513			header->ctl_table_arg = ctl_table_arg;
1514	} else {
1515		header = kzalloc(sizeof(*header) +
1516				 sizeof(*subheaders)*nr_subheaders, GFP_KERNEL);
1517		if (!header)
1518			goto out;
1519
1520		subheaders = (struct ctl_table_header **) (header + 1);
1521		subheader = subheaders;
1522		header->ctl_table_arg = ctl_table_arg;
1523
1524		if (register_leaf_sysctl_tables(new_path, pos, &subheader,
1525						set, table))
1526			goto err_register_leaves;
1527	}
1528
1529out:
1530	kfree(new_path);
1531	return header;
1532
1533err_register_leaves:
1534	while (subheader > subheaders) {
1535		struct ctl_table_header *subh = *(--subheader);
1536		struct ctl_table *table = subh->ctl_table_arg;
1537		unregister_sysctl_table(subh);
1538		kfree(table);
1539	}
1540	kfree(header);
1541	header = NULL;
1542	goto out;
1543}
1544
1545/**
1546 * register_sysctl_table_path - register a sysctl table hierarchy
1547 * @path: The path to the directory the sysctl table is in.
1548 * @table: the top-level table structure
1549 *
1550 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1551 * array. A completely 0 filled entry terminates the table.
1552 *
1553 * See __register_sysctl_paths for more details.
1554 */
1555struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
1556						struct ctl_table *table)
1557{
1558	return __register_sysctl_paths(&sysctl_table_root.default_set,
1559					path, table);
1560}
1561EXPORT_SYMBOL(register_sysctl_paths);
1562
1563/**
1564 * register_sysctl_table - register a sysctl table hierarchy
1565 * @table: the top-level table structure
1566 *
1567 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1568 * array. A completely 0 filled entry terminates the table.
1569 *
1570 * See register_sysctl_paths for more details.
1571 */
1572struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
1573{
1574	static const struct ctl_path null_path[] = { {} };
1575
1576	return register_sysctl_paths(null_path, table);
1577}
1578EXPORT_SYMBOL(register_sysctl_table);
1579
1580static void put_links(struct ctl_table_header *header)
1581{
1582	struct ctl_table_set *root_set = &sysctl_table_root.default_set;
1583	struct ctl_table_root *root = header->root;
1584	struct ctl_dir *parent = header->parent;
1585	struct ctl_dir *core_parent;
1586	struct ctl_table *entry;
1587
1588	if (header->set == root_set)
1589		return;
1590
1591	core_parent = xlate_dir(root_set, parent);
1592	if (IS_ERR(core_parent))
1593		return;
1594
1595	for (entry = header->ctl_table; entry->procname; entry++) {
1596		struct ctl_table_header *link_head;
1597		struct ctl_table *link;
1598		const char *name = entry->procname;
1599
1600		link = find_entry(&link_head, core_parent, name, strlen(name));
1601		if (link &&
1602		    ((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
1603		     (S_ISLNK(link->mode) && (link->data == root)))) {
1604			drop_sysctl_table(link_head);
1605		}
1606		else {
1607			pr_err("sysctl link missing during unregister: ");
1608			sysctl_print_dir(parent);
1609			pr_cont("/%s\n", name);
1610		}
1611	}
1612}
1613
1614static void drop_sysctl_table(struct ctl_table_header *header)
1615{
1616	struct ctl_dir *parent = header->parent;
1617
1618	if (--header->nreg)
1619		return;
1620
1621	put_links(header);
1622	start_unregistering(header);
 
 
 
1623	if (!--header->count)
1624		kfree_rcu(header, rcu);
1625
1626	if (parent)
1627		drop_sysctl_table(&parent->header);
1628}
1629
1630/**
1631 * unregister_sysctl_table - unregister a sysctl table hierarchy
1632 * @header: the header returned from register_sysctl_table
1633 *
1634 * Unregisters the sysctl table and all children. proc entries may not
1635 * actually be removed until they are no longer used by anyone.
1636 */
1637void unregister_sysctl_table(struct ctl_table_header * header)
1638{
1639	int nr_subheaders;
1640	might_sleep();
1641
1642	if (header == NULL)
1643		return;
1644
1645	nr_subheaders = count_subheaders(header->ctl_table_arg);
1646	if (unlikely(nr_subheaders > 1)) {
1647		struct ctl_table_header **subheaders;
1648		int i;
1649
1650		subheaders = (struct ctl_table_header **)(header + 1);
1651		for (i = nr_subheaders -1; i >= 0; i--) {
1652			struct ctl_table_header *subh = subheaders[i];
1653			struct ctl_table *table = subh->ctl_table_arg;
1654			unregister_sysctl_table(subh);
1655			kfree(table);
1656		}
1657		kfree(header);
1658		return;
1659	}
1660
1661	spin_lock(&sysctl_lock);
1662	drop_sysctl_table(header);
1663	spin_unlock(&sysctl_lock);
1664}
1665EXPORT_SYMBOL(unregister_sysctl_table);
1666
1667void setup_sysctl_set(struct ctl_table_set *set,
1668	struct ctl_table_root *root,
1669	int (*is_seen)(struct ctl_table_set *))
1670{
1671	memset(set, 0, sizeof(*set));
1672	set->is_seen = is_seen;
1673	init_header(&set->dir.header, root, set, NULL, root_table);
1674}
1675
1676void retire_sysctl_set(struct ctl_table_set *set)
1677{
1678	WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
1679}
1680
1681int __init proc_sys_init(void)
1682{
1683	struct proc_dir_entry *proc_sys_root;
1684
1685	proc_sys_root = proc_mkdir("sys", NULL);
1686	proc_sys_root->proc_iops = &proc_sys_dir_operations;
1687	proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
1688	proc_sys_root->nlink = 0;
1689
1690	return sysctl_init();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1691}