[net-next-2.6.git] / fs / proc / proc_sysctl.c

/*
 * /proc/sys support
 */
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include "internal.h"

static const struct dentry_operations proc_sys_dentry_operations;
static const struct file_operations proc_sys_file_operations;
static const struct inode_operations proc_sys_inode_operations;
static const struct file_operations proc_sys_dir_file_operations;
static const struct inode_operations proc_sys_dir_operations;

static struct inode *proc_sys_make_inode(struct super_block *sb,
		struct ctl_table_header *head, struct ctl_table *table)
{
	struct inode *inode;
	struct proc_inode *ei;

	inode = new_inode(sb);
	if (!inode)
		goto out;

	inode->i_ino = get_next_ino();

	sysctl_head_get(head);
	ei = PROC_I(inode);
	ei->sysctl = head;
	ei->sysctl_entry = table;

	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */
	inode->i_mode = table->mode;
	if (!table->child) {
		inode->i_mode |= S_IFREG;
		inode->i_op = &proc_sys_inode_operations;
		inode->i_fop = &proc_sys_file_operations;
	} else {
		inode->i_mode |= S_IFDIR;
		inode->i_nlink = 0;
		inode->i_op = &proc_sys_dir_operations;
		inode->i_fop = &proc_sys_dir_file_operations;
	}
out:
	return inode;
}

static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
{
	int len;
	for ( ; p->procname; p++) {

		if (!p->procname)
			continue;

		len = strlen(p->procname);
		if (len != name->len)
			continue;

		if (memcmp(p->procname, name->name, len) != 0)
			continue;

		/* I have a match */
		return p;
	}
	return NULL;
}

static struct ctl_table_header *grab_header(struct inode *inode)
{
	if (PROC_I(inode)->sysctl)
		return sysctl_head_grab(PROC_I(inode)->sysctl);
	else
		return sysctl_head_next(NULL);
}

static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
					struct nameidata *nd)
{
	struct ctl_table_header *head = grab_header(dir);
	struct ctl_table *table = PROC_I(dir)->sysctl_entry;
	struct ctl_table_header *h = NULL;
	struct qstr *name = &dentry->d_name;
	struct ctl_table *p;
	struct inode *inode;
	struct dentry *err = ERR_PTR(-ENOENT);

	if (IS_ERR(head))
		return ERR_CAST(head);

	if (table && !table->child) {
		WARN_ON(1);
		goto out;
	}

	table = table ? table->child : head->ctl_table;

	p = find_in_table(table, name);
	if (!p) {
		for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
			if (h->attached_to != table)
				continue;
			p = find_in_table(h->attached_by, name);
			if (p)
				break;
		}
	}

	if (!p)
		goto out;

	err = ERR_PTR(-ENOMEM);
	inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
	if (h)
		sysctl_head_finish(h);

	if (!inode)
		goto out;

	err = NULL;
	dentry->d_op = &proc_sys_dentry_operations;
	d_add(dentry, inode);

out:
	sysctl_head_finish(head);
	return err;
}

static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
		size_t count, loff_t *ppos, int write)
{
	struct inode *inode = filp->f_path.dentry->d_inode;
	struct ctl_table_header *head = grab_header(inode);
	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
	ssize_t error;
	size_t res;

	if (IS_ERR(head))
		return PTR_ERR(head);

	/*
	 * At this point we know that the sysctl was not unregistered
	 * and won't be until we finish.
	 */
	error = -EPERM;
	if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
		goto out;

	/* if that can happen at all, it should be -EINVAL, not -EISDIR */
	error = -EINVAL;
	if (!table->proc_handler)
		goto out;

	/* careful: calling conventions are nasty here */
	res = count;
	error = table->proc_handler(table, write, buf, &res, ppos);
	if (!error)
		error = res;
out:
	sysctl_head_finish(head);

	return error;
}

static ssize_t proc_sys_read(struct file *filp, char __user *buf,
				size_t count, loff_t *ppos)
{
	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
}

static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
				size_t count, loff_t *ppos)
{
	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
}


static int proc_sys_fill_cache(struct file *filp, void *dirent,
				filldir_t filldir,
				struct ctl_table_header *head,
				struct ctl_table *table)
{
	struct dentry *child, *dir = filp->f_path.dentry;
	struct inode *inode;
	struct qstr qname;
	ino_t ino = 0;
	unsigned type = DT_UNKNOWN;

	qname.name = table->procname;
	qname.len  = strlen(table->procname);
	qname.hash = full_name_hash(qname.name, qname.len);

	child = d_lookup(dir, &qname);
	if (!child) {
		child = d_alloc(dir, &qname);
		if (child) {
			inode = proc_sys_make_inode(dir->d_sb, head, table);
			if (!inode) {
				dput(child);
				return -ENOMEM;
			} else {
				child->d_op = &proc_sys_dentry_operations;
				d_add(child, inode);
			}
		} else {
			return -ENOMEM;
		}
	}
	inode = child->d_inode;
	ino  = inode->i_ino;
	type = inode->i_mode >> 12;
	dput(child);
	return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
}

static int scan(struct ctl_table_header *head, ctl_table *table,
		unsigned long *pos, struct file *file,
		void *dirent, filldir_t filldir)
{

	for (; table->procname; table++, (*pos)++) {
		int res;

		/* Can't do anything without a proc name */
		if (!table->procname)
			continue;

		if (*pos < file->f_pos)
			continue;

		res = proc_sys_fill_cache(file, dirent, filldir, head, table);
		if (res)
			return res;

		file->f_pos = *pos + 1;
	}
	return 0;
}

static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
	struct dentry *dentry = filp->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	struct ctl_table_header *head = grab_header(inode);
	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
	struct ctl_table_header *h = NULL;
	unsigned long pos;
	int ret = -EINVAL;

	if (IS_ERR(head))
		return PTR_ERR(head);

	if (table && !table->child) {
		WARN_ON(1);
		goto out;
	}

	table = table ? table->child : head->ctl_table;

	ret = 0;
	/* Avoid a switch here: arm builds fail with missing __cmpdi2 */
	if (filp->f_pos == 0) {
		if (filldir(dirent, ".", 1, filp->f_pos,
				inode->i_ino, DT_DIR) < 0)
			goto out;
		filp->f_pos++;
	}
	if (filp->f_pos == 1) {
		if (filldir(dirent, "..", 2, filp->f_pos,
				parent_ino(dentry), DT_DIR) < 0)
			goto out;
		filp->f_pos++;
	}
	pos = 2;

	ret = scan(head, table, &pos, filp, dirent, filldir);
	if (ret)
		goto out;

	for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
		if (h->attached_to != table)
			continue;
		ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
		if (ret) {
			sysctl_head_finish(h);
			break;
		}
	}
	ret = 1;
out:
	sysctl_head_finish(head);
	return ret;
}

static int proc_sys_permission(struct inode *inode, int mask)
{
	/*
	 * sysctl entries that are not writeable,
	 * are _NOT_ writeable, capabilities or not.
	 */
	struct ctl_table_header *head;
	struct ctl_table *table;
	int error;

	/* Executable files are not allowed under /proc/sys/ */
	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
		return -EACCES;

	head = grab_header(inode);
	if (IS_ERR(head))
		return PTR_ERR(head);

	table = PROC_I(inode)->sysctl_entry;
	if (!table) /* global root - r-xr-xr-x */
		error = mask & MAY_WRITE ? -EACCES : 0;
	else /* Use the permissions on the sysctl table entry */
		error = sysctl_perm(head->root, table, mask);

	sysctl_head_finish(head);
	return error;
}

static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	int error;

	if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
		return -EPERM;

	error = inode_change_ok(inode, attr);
	if (error)
		return error;

	if ((attr->ia_valid & ATTR_SIZE) &&
	    attr->ia_size != i_size_read(inode)) {
		error = vmtruncate(inode, attr->ia_size);
		if (error)
			return error;
	}

	setattr_copy(inode, attr);
	mark_inode_dirty(inode);
	return 0;
}

static int proc_sys_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
	struct inode *inode = dentry->d_inode;
	struct ctl_table_header *head = grab_header(inode);
	struct ctl_table *table = PROC_I(inode)->sysctl_entry;

	if (IS_ERR(head))
		return PTR_ERR(head);

	generic_fillattr(inode, stat);
	if (table)
		stat->mode = (stat->mode & S_IFMT) | table->mode;

	sysctl_head_finish(head);
	return 0;
}

static const struct file_operations proc_sys_file_operations = {
	.read		= proc_sys_read,
	.write		= proc_sys_write,
	.llseek		= default_llseek,
};

static const struct file_operations proc_sys_dir_file_operations = {
	.readdir	= proc_sys_readdir,
	.llseek		= generic_file_llseek,
};

static const struct inode_operations proc_sys_inode_operations = {
	.permission	= proc_sys_permission,
	.setattr	= proc_sys_setattr,
	.getattr	= proc_sys_getattr,
};

static const struct inode_operations proc_sys_dir_operations = {
	.lookup		= proc_sys_lookup,
	.permission	= proc_sys_permission,
	.setattr	= proc_sys_setattr,
	.getattr	= proc_sys_getattr,
};

static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)
{
	return !PROC_I(dentry->d_inode)->sysctl->unregistering;
}

static int proc_sys_delete(struct dentry *dentry)
{
	return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
}

static int proc_sys_compare(struct dentry *dir, struct qstr *qstr,
			    struct qstr *name)
{
	struct dentry *dentry = container_of(qstr, struct dentry, d_name);
	if (qstr->len != name->len)
		return 1;
	if (memcmp(qstr->name, name->name, name->len))
		return 1;
	return !sysctl_is_seen(PROC_I(dentry->d_inode)->sysctl);
}

static const struct dentry_operations proc_sys_dentry_operations = {
	.d_revalidate	= proc_sys_revalidate,
	.d_delete	= proc_sys_delete,
	.d_compare	= proc_sys_compare,
};

int __init proc_sys_init(void)
{
	struct proc_dir_entry *proc_sys_root;

	proc_sys_root = proc_mkdir("sys", NULL);
	proc_sys_root->proc_iops = &proc_sys_dir_operations;
	proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
	proc_sys_root->nlink = 0;
	return 0;
}
Commit	Line	Data
77b14db5 EB	1	/*
	2	* /proc/sys support
	3	*/
1e0edd3f	4	#include <linux/init.h>
77b14db5 EB	5	#include <linux/sysctl.h>
	6	#include <linux/proc_fs.h>
	7	#include <linux/security.h>
	8	#include "internal.h"
	9
d72f71eb	10	static const struct dentry_operations proc_sys_dentry_operations;
77b14db5	11	static const struct file_operations proc_sys_file_operations;
03a44825	12	static const struct inode_operations proc_sys_inode_operations;
9043476f AV	13	static const struct file_operations proc_sys_dir_file_operations;
9043476f AV	14	static const struct inode_operations proc_sys_dir_operations;
77b14db5	15
9043476f AV	16	static struct inode proc_sys_make_inode(struct super_block sb,
9043476f AV	17	struct ctl_table_header head, struct ctl_table table)
77b14db5 EB	18	{
77b14db5 EB	19	struct inode *inode;
9043476f	20	struct proc_inode *ei;
77b14db5	21
9043476f	22	inode = new_inode(sb);
77b14db5 EB	23	if (!inode)
	24	goto out;
	25
85fe4025 CH	26	inode->i_ino = get_next_ino();
85fe4025 CH	27
9043476f	28	sysctl_head_get(head);
77b14db5	29	ei = PROC_I(inode);
9043476f AV	30	ei->sysctl = head;
	31	ei->sysctl_entry = table;
	32
77b14db5	33	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
86a71dbd	34	inode->i_flags \|= S_PRIVATE; /* tell selinux to ignore this inode */
9043476f AV	35	inode->i_mode = table->mode;
	36	if (!table->child) {
	37	inode->i_mode \|= S_IFREG;
	38	inode->i_op = &proc_sys_inode_operations;
	39	inode->i_fop = &proc_sys_file_operations;
	40	} else {
	41	inode->i_mode \|= S_IFDIR;
	42	inode->i_nlink = 0;
	43	inode->i_op = &proc_sys_dir_operations;
	44	inode->i_fop = &proc_sys_dir_file_operations;
	45	}
77b14db5 EB	46	out:
	47	return inode;
	48	}
	49
9043476f	50	static struct ctl_table find_in_table(struct ctl_table p, struct qstr *name)
77b14db5 EB	51	{
77b14db5 EB	52	int len;
2315ffa0	53	for ( ; p->procname; p++) {
77b14db5	54
9043476f	55	if (!p->procname)
77b14db5 EB	56	continue;
77b14db5 EB	57
9043476f	58	len = strlen(p->procname);
77b14db5 EB	59	if (len != name->len)
	60	continue;
	61
9043476f	62	if (memcmp(p->procname, name->name, len) != 0)
77b14db5 EB	63	continue;
	64
	65	/* I have a match */
9043476f	66	return p;
77b14db5 EB	67	}
	68	return NULL;
	69	}
	70
81324364	71	static struct ctl_table_header grab_header(struct inode inode)
77b14db5	72	{
9043476f AV	73	if (PROC_I(inode)->sysctl)
	74	return sysctl_head_grab(PROC_I(inode)->sysctl);
	75	else
	76	return sysctl_head_next(NULL);
	77	}
77b14db5	78
9043476f AV	79	static struct dentry proc_sys_lookup(struct inode dir, struct dentry *dentry,
	80	struct nameidata *nd)
	81	{
	82	struct ctl_table_header *head = grab_header(dir);
	83	struct ctl_table *table = PROC_I(dir)->sysctl_entry;
	84	struct ctl_table_header *h = NULL;
	85	struct qstr *name = &dentry->d_name;
	86	struct ctl_table *p;
	87	struct inode *inode;
	88	struct dentry *err = ERR_PTR(-ENOENT);
77b14db5	89
9043476f AV	90	if (IS_ERR(head))
9043476f AV	91	return ERR_CAST(head);
77b14db5	92
9043476f AV	93	if (table && !table->child) {
	94	WARN_ON(1);
	95	goto out;
77b14db5	96	}
77b14db5	97
9043476f	98	table = table ? table->child : head->ctl_table;
77b14db5	99
9043476f AV	100	p = find_in_table(table, name);
	101	if (!p) {
	102	for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
	103	if (h->attached_to != table)
	104	continue;
	105	p = find_in_table(h->attached_by, name);
	106	if (p)
	107	break;
	108	}
77b14db5	109	}
77b14db5	110
9043476f	111	if (!p)
77b14db5 EB	112	goto out;
	113
	114	err = ERR_PTR(-ENOMEM);
9043476f AV	115	inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
	116	if (h)
	117	sysctl_head_finish(h);
	118
77b14db5 EB	119	if (!inode)
	120	goto out;
	121
	122	err = NULL;
	123	dentry->d_op = &proc_sys_dentry_operations;
	124	d_add(dentry, inode);
	125
	126	out:
	127	sysctl_head_finish(head);
	128	return err;
	129	}
	130
7708bfb1 PE	131	static ssize_t proc_sys_call_handler(struct file filp, void __user buf,
7708bfb1 PE	132	size_t count, loff_t *ppos, int write)
77b14db5	133	{
9043476f AV	134	struct inode *inode = filp->f_path.dentry->d_inode;
	135	struct ctl_table_header *head = grab_header(inode);
	136	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
2a2da53b DH	137	ssize_t error;
2a2da53b DH	138	size_t res;
77b14db5	139
9043476f AV	140	if (IS_ERR(head))
9043476f AV	141	return PTR_ERR(head);
77b14db5 EB	142
	143	/*
	144	* At this point we know that the sysctl was not unregistered
	145	* and won't be until we finish.
	146	*/
	147	error = -EPERM;
d7321cd6	148	if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
77b14db5 EB	149	goto out;
77b14db5 EB	150
9043476f AV	151	/* if that can happen at all, it should be -EINVAL, not -EISDIR */
	152	error = -EINVAL;
	153	if (!table->proc_handler)
	154	goto out;
	155
77b14db5 EB	156	/* careful: calling conventions are nasty here */
77b14db5 EB	157	res = count;
8d65af78	158	error = table->proc_handler(table, write, buf, &res, ppos);
77b14db5 EB	159	if (!error)
	160	error = res;
	161	out:
	162	sysctl_head_finish(head);
	163
	164	return error;
	165	}
	166
7708bfb1	167	static ssize_t proc_sys_read(struct file filp, char __user buf,
77b14db5 EB	168	size_t count, loff_t *ppos)
77b14db5 EB	169	{
7708bfb1 PE	170	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
7708bfb1 PE	171	}
77b14db5	172
7708bfb1 PE	173	static ssize_t proc_sys_write(struct file filp, const char __user buf,
	174	size_t count, loff_t *ppos)
	175	{
	176	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
77b14db5 EB	177	}
	178
	179
	180	static int proc_sys_fill_cache(struct file filp, void dirent,
9043476f AV	181	filldir_t filldir,
	182	struct ctl_table_header *head,
	183	struct ctl_table *table)
77b14db5	184	{
77b14db5 EB	185	struct dentry child, dir = filp->f_path.dentry;
	186	struct inode *inode;
	187	struct qstr qname;
	188	ino_t ino = 0;
	189	unsigned type = DT_UNKNOWN;
77b14db5 EB	190
	191	qname.name = table->procname;
	192	qname.len = strlen(table->procname);
	193	qname.hash = full_name_hash(qname.name, qname.len);
	194
77b14db5 EB	195	child = d_lookup(dir, &qname);
77b14db5 EB	196	if (!child) {
9043476f AV	197	child = d_alloc(dir, &qname);
	198	if (child) {
	199	inode = proc_sys_make_inode(dir->d_sb, head, table);
	200	if (!inode) {
	201	dput(child);
	202	return -ENOMEM;
	203	} else {
	204	child->d_op = &proc_sys_dentry_operations;
	205	d_add(child, inode);
77b14db5	206	}
9043476f AV	207	} else {
9043476f AV	208	return -ENOMEM;
77b14db5 EB	209	}
77b14db5 EB	210	}
77b14db5	211	inode = child->d_inode;
9043476f AV	212	ino = inode->i_ino;
9043476f AV	213	type = inode->i_mode >> 12;
77b14db5	214	dput(child);
9043476f AV	215	return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
	216	}
	217
	218	static int scan(struct ctl_table_header head, ctl_table table,
	219	unsigned long pos, struct file file,
	220	void *dirent, filldir_t filldir)
	221	{
	222
2315ffa0	223	for (; table->procname; table++, (*pos)++) {
9043476f AV	224	int res;
	225
	226	/* Can't do anything without a proc name */
	227	if (!table->procname)
	228	continue;
	229
	230	if (*pos < file->f_pos)
	231	continue;
	232
	233	res = proc_sys_fill_cache(file, dirent, filldir, head, table);
	234	if (res)
	235	return res;
	236
	237	file->f_pos = *pos + 1;
	238	}
	239	return 0;
77b14db5 EB	240	}
	241
	242	static int proc_sys_readdir(struct file filp, void dirent, filldir_t filldir)
	243	{
9043476f	244	struct dentry *dentry = filp->f_path.dentry;
77b14db5	245	struct inode *inode = dentry->d_inode;
9043476f AV	246	struct ctl_table_header *head = grab_header(inode);
	247	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
	248	struct ctl_table_header *h = NULL;
77b14db5	249	unsigned long pos;
9043476f AV	250	int ret = -EINVAL;
	251
	252	if (IS_ERR(head))
	253	return PTR_ERR(head);
77b14db5	254
9043476f AV	255	if (table && !table->child) {
9043476f AV	256	WARN_ON(1);
77b14db5	257	goto out;
9043476f AV	258	}
	259
	260	table = table ? table->child : head->ctl_table;
77b14db5 EB	261
	262	ret = 0;
	263	/* Avoid a switch here: arm builds fail with missing __cmpdi2 */
	264	if (filp->f_pos == 0) {
	265	if (filldir(dirent, ".", 1, filp->f_pos,
	266	inode->i_ino, DT_DIR) < 0)
	267	goto out;
	268	filp->f_pos++;
	269	}
	270	if (filp->f_pos == 1) {
	271	if (filldir(dirent, "..", 2, filp->f_pos,
	272	parent_ino(dentry), DT_DIR) < 0)
	273	goto out;
	274	filp->f_pos++;
	275	}
	276	pos = 2;
	277
9043476f AV	278	ret = scan(head, table, &pos, filp, dirent, filldir);
	279	if (ret)
	280	goto out;
77b14db5	281
9043476f AV	282	for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
9043476f AV	283	if (h->attached_to != table)
77b14db5	284	continue;
9043476f AV	285	ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
	286	if (ret) {
	287	sysctl_head_finish(h);
	288	break;
77b14db5 EB	289	}
	290	}
	291	ret = 1;
	292	out:
	293	sysctl_head_finish(head);
	294	return ret;
	295	}
	296
e6305c43	297	static int proc_sys_permission(struct inode *inode, int mask)
77b14db5 EB	298	{
	299	/*
	300	* sysctl entries that are not writeable,
	301	* are _NOT_ writeable, capabilities or not.
	302	*/
f696a365 MS	303	struct ctl_table_header *head;
f696a365 MS	304	struct ctl_table *table;
77b14db5 EB	305	int error;
77b14db5 EB	306
f696a365 MS	307	/* Executable files are not allowed under /proc/sys/ */
	308	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
	309	return -EACCES;
	310
	311	head = grab_header(inode);
9043476f AV	312	if (IS_ERR(head))
9043476f AV	313	return PTR_ERR(head);
77b14db5	314
f696a365	315	table = PROC_I(inode)->sysctl_entry;
9043476f AV	316	if (!table) /* global root - r-xr-xr-x */
	317	error = mask & MAY_WRITE ? -EACCES : 0;
	318	else /* Use the permissions on the sysctl table entry */
	319	error = sysctl_perm(head->root, table, mask);
77b14db5	320
77b14db5 EB	321	sysctl_head_finish(head);
	322	return error;
	323	}
	324
	325	static int proc_sys_setattr(struct dentry dentry, struct iattr attr)
	326	{
	327	struct inode *inode = dentry->d_inode;
	328	int error;
	329
	330	if (attr->ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID))
	331	return -EPERM;
	332
	333	error = inode_change_ok(inode, attr);
1025774c CH	334	if (error)
	335	return error;
	336
	337	if ((attr->ia_valid & ATTR_SIZE) &&
	338	attr->ia_size != i_size_read(inode)) {
	339	error = vmtruncate(inode, attr->ia_size);
	340	if (error)
	341	return error;
	342	}
77b14db5	343
1025774c CH	344	setattr_copy(inode, attr);
	345	mark_inode_dirty(inode);
	346	return 0;
77b14db5 EB	347	}
77b14db5 EB	348
9043476f AV	349	static int proc_sys_getattr(struct vfsmount mnt, struct dentry dentry, struct kstat *stat)
	350	{
	351	struct inode *inode = dentry->d_inode;
	352	struct ctl_table_header *head = grab_header(inode);
	353	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
	354
	355	if (IS_ERR(head))
	356	return PTR_ERR(head);
	357
	358	generic_fillattr(inode, stat);
	359	if (table)
	360	stat->mode = (stat->mode & S_IFMT) \| table->mode;
	361
	362	sysctl_head_finish(head);
	363	return 0;
	364	}
	365
77b14db5 EB	366	static const struct file_operations proc_sys_file_operations = {
	367	.read = proc_sys_read,
	368	.write = proc_sys_write,
6038f373	369	.llseek = default_llseek,
9043476f AV	370	};
	371
	372	static const struct file_operations proc_sys_dir_file_operations = {
77b14db5	373	.readdir = proc_sys_readdir,
3222a3e5	374	.llseek = generic_file_llseek,
77b14db5 EB	375	};
77b14db5 EB	376
03a44825	377	static const struct inode_operations proc_sys_inode_operations = {
9043476f AV	378	.permission = proc_sys_permission,
	379	.setattr = proc_sys_setattr,
	380	.getattr = proc_sys_getattr,
	381	};
	382
	383	static const struct inode_operations proc_sys_dir_operations = {
77b14db5 EB	384	.lookup = proc_sys_lookup,
	385	.permission = proc_sys_permission,
	386	.setattr = proc_sys_setattr,
9043476f	387	.getattr = proc_sys_getattr,
77b14db5 EB	388	};
	389
	390	static int proc_sys_revalidate(struct dentry dentry, struct nameidata nd)
	391	{
9043476f AV	392	return !PROC_I(dentry->d_inode)->sysctl->unregistering;
	393	}
	394
	395	static int proc_sys_delete(struct dentry *dentry)
	396	{
	397	return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
	398	}
	399
	400	static int proc_sys_compare(struct dentry dir, struct qstr qstr,
	401	struct qstr *name)
	402	{
	403	struct dentry *dentry = container_of(qstr, struct dentry, d_name);
	404	if (qstr->len != name->len)
	405	return 1;
	406	if (memcmp(qstr->name, name->name, name->len))
	407	return 1;
	408	return !sysctl_is_seen(PROC_I(dentry->d_inode)->sysctl);
77b14db5 EB	409	}
77b14db5 EB	410
d72f71eb	411	static const struct dentry_operations proc_sys_dentry_operations = {
77b14db5	412	.d_revalidate = proc_sys_revalidate,
9043476f AV	413	.d_delete = proc_sys_delete,
9043476f AV	414	.d_compare = proc_sys_compare,
77b14db5 EB	415	};
77b14db5 EB	416
1e0edd3f	417	int __init proc_sys_init(void)
77b14db5	418	{
e1675231 AD	419	struct proc_dir_entry *proc_sys_root;
e1675231 AD	420
77b14db5	421	proc_sys_root = proc_mkdir("sys", NULL);
9043476f AV	422	proc_sys_root->proc_iops = &proc_sys_dir_operations;
9043476f AV	423	proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
77b14db5 EB	424	proc_sys_root->nlink = 0;
	425	return 0;
	426	}