[mirror_ubuntu-zesty-kernel.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 <linux/namei.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;
	d_set_d_op(dentry, &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 {
				d_set_d_op(child, &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,unsigned int flags)
{
	/*
	 * sysctl entries that are not writeable,
	 * are _NOT_ writeable, capabilities or not.
	 */
	struct ctl_table_header *head;
	struct ctl_table *table;
	int error;

	if (flags & IPERM_FLAG_RCU)
		return -ECHILD;

	/* 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)
{
	if (nd->flags & LOOKUP_RCU)
		return -ECHILD;
	return !PROC_I(dentry->d_inode)->sysctl->unregistering;
}

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

static int proc_sys_compare(const struct dentry *parent,
		const struct inode *pinode,
		const struct dentry *dentry, const struct inode *inode,
		unsigned int len, const char *str, const struct qstr *name)
{
	/* Although proc doesn't have negative dentries, rcu-walk means
	 * that inode here can be NULL */
	if (!inode)
		return 0;
	if (name->len != len)
		return 1;
	if (memcmp(name->name, str, len))
		return 1;
	return !sysctl_is_seen(PROC_I(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>
34286d66	8	#include <linux/namei.h>
77b14db5 EB	9	#include "internal.h"
77b14db5 EB	10
d72f71eb	11	static const struct dentry_operations proc_sys_dentry_operations;
77b14db5	12	static const struct file_operations proc_sys_file_operations;
03a44825	13	static const struct inode_operations proc_sys_inode_operations;
9043476f AV	14	static const struct file_operations proc_sys_dir_file_operations;
9043476f AV	15	static const struct inode_operations proc_sys_dir_operations;
77b14db5	16
9043476f AV	17	static struct inode proc_sys_make_inode(struct super_block sb,
9043476f AV	18	struct ctl_table_header head, struct ctl_table table)
77b14db5 EB	19	{
77b14db5 EB	20	struct inode *inode;
9043476f	21	struct proc_inode *ei;
77b14db5	22
9043476f	23	inode = new_inode(sb);
77b14db5 EB	24	if (!inode)
	25	goto out;
	26
85fe4025 CH	27	inode->i_ino = get_next_ino();
85fe4025 CH	28
9043476f	29	sysctl_head_get(head);
77b14db5	30	ei = PROC_I(inode);
9043476f AV	31	ei->sysctl = head;
	32	ei->sysctl_entry = table;
	33
77b14db5	34	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
86a71dbd	35	inode->i_flags \|= S_PRIVATE; /* tell selinux to ignore this inode */
9043476f AV	36	inode->i_mode = table->mode;
	37	if (!table->child) {
	38	inode->i_mode \|= S_IFREG;
	39	inode->i_op = &proc_sys_inode_operations;
	40	inode->i_fop = &proc_sys_file_operations;
	41	} else {
	42	inode->i_mode \|= S_IFDIR;
	43	inode->i_nlink = 0;
	44	inode->i_op = &proc_sys_dir_operations;
	45	inode->i_fop = &proc_sys_dir_file_operations;
	46	}
77b14db5 EB	47	out:
	48	return inode;
	49	}
	50
9043476f	51	static struct ctl_table find_in_table(struct ctl_table p, struct qstr *name)
77b14db5 EB	52	{
77b14db5 EB	53	int len;
2315ffa0	54	for ( ; p->procname; p++) {
77b14db5	55
9043476f	56	if (!p->procname)
77b14db5 EB	57	continue;
77b14db5 EB	58
9043476f	59	len = strlen(p->procname);
77b14db5 EB	60	if (len != name->len)
	61	continue;
	62
9043476f	63	if (memcmp(p->procname, name->name, len) != 0)
77b14db5 EB	64	continue;
	65
	66	/* I have a match */
9043476f	67	return p;
77b14db5 EB	68	}
	69	return NULL;
	70	}
	71
81324364	72	static struct ctl_table_header grab_header(struct inode inode)
77b14db5	73	{
9043476f AV	74	if (PROC_I(inode)->sysctl)
	75	return sysctl_head_grab(PROC_I(inode)->sysctl);
	76	else
	77	return sysctl_head_next(NULL);
	78	}
77b14db5	79
9043476f AV	80	static struct dentry proc_sys_lookup(struct inode dir, struct dentry *dentry,
	81	struct nameidata *nd)
	82	{
	83	struct ctl_table_header *head = grab_header(dir);
	84	struct ctl_table *table = PROC_I(dir)->sysctl_entry;
	85	struct ctl_table_header *h = NULL;
	86	struct qstr *name = &dentry->d_name;
	87	struct ctl_table *p;
	88	struct inode *inode;
	89	struct dentry *err = ERR_PTR(-ENOENT);
77b14db5	90
9043476f AV	91	if (IS_ERR(head))
9043476f AV	92	return ERR_CAST(head);
77b14db5	93
9043476f AV	94	if (table && !table->child) {
	95	WARN_ON(1);
	96	goto out;
77b14db5	97	}
77b14db5	98
9043476f	99	table = table ? table->child : head->ctl_table;
77b14db5	100
9043476f AV	101	p = find_in_table(table, name);
	102	if (!p) {
	103	for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
	104	if (h->attached_to != table)
	105	continue;
	106	p = find_in_table(h->attached_by, name);
	107	if (p)
	108	break;
	109	}
77b14db5	110	}
77b14db5	111
9043476f	112	if (!p)
77b14db5 EB	113	goto out;
	114
	115	err = ERR_PTR(-ENOMEM);
9043476f AV	116	inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
	117	if (h)
	118	sysctl_head_finish(h);
	119
77b14db5 EB	120	if (!inode)
	121	goto out;
	122
	123	err = NULL;
fb045adb	124	d_set_d_op(dentry, &proc_sys_dentry_operations);
77b14db5 EB	125	d_add(dentry, inode);
	126
	127	out:
	128	sysctl_head_finish(head);
	129	return err;
	130	}
	131
7708bfb1 PE	132	static ssize_t proc_sys_call_handler(struct file filp, void __user buf,
7708bfb1 PE	133	size_t count, loff_t *ppos, int write)
77b14db5	134	{
9043476f AV	135	struct inode *inode = filp->f_path.dentry->d_inode;
	136	struct ctl_table_header *head = grab_header(inode);
	137	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
2a2da53b DH	138	ssize_t error;
2a2da53b DH	139	size_t res;
77b14db5	140
9043476f AV	141	if (IS_ERR(head))
9043476f AV	142	return PTR_ERR(head);
77b14db5 EB	143
	144	/*
	145	* At this point we know that the sysctl was not unregistered
	146	* and won't be until we finish.
	147	*/
	148	error = -EPERM;
d7321cd6	149	if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
77b14db5 EB	150	goto out;
77b14db5 EB	151
9043476f AV	152	/* if that can happen at all, it should be -EINVAL, not -EISDIR */
	153	error = -EINVAL;
	154	if (!table->proc_handler)
	155	goto out;
	156
77b14db5 EB	157	/* careful: calling conventions are nasty here */
77b14db5 EB	158	res = count;
8d65af78	159	error = table->proc_handler(table, write, buf, &res, ppos);
77b14db5 EB	160	if (!error)
	161	error = res;
	162	out:
	163	sysctl_head_finish(head);
	164
	165	return error;
	166	}
	167
7708bfb1	168	static ssize_t proc_sys_read(struct file filp, char __user buf,
77b14db5 EB	169	size_t count, loff_t *ppos)
77b14db5 EB	170	{
7708bfb1 PE	171	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
7708bfb1 PE	172	}
77b14db5	173
7708bfb1 PE	174	static ssize_t proc_sys_write(struct file filp, const char __user buf,
	175	size_t count, loff_t *ppos)
	176	{
	177	return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
77b14db5 EB	178	}
	179
	180
	181	static int proc_sys_fill_cache(struct file filp, void dirent,
9043476f AV	182	filldir_t filldir,
	183	struct ctl_table_header *head,
	184	struct ctl_table *table)
77b14db5	185	{
77b14db5 EB	186	struct dentry child, dir = filp->f_path.dentry;
	187	struct inode *inode;
	188	struct qstr qname;
	189	ino_t ino = 0;
	190	unsigned type = DT_UNKNOWN;
77b14db5 EB	191
	192	qname.name = table->procname;
	193	qname.len = strlen(table->procname);
	194	qname.hash = full_name_hash(qname.name, qname.len);
	195
77b14db5 EB	196	child = d_lookup(dir, &qname);
77b14db5 EB	197	if (!child) {
9043476f AV	198	child = d_alloc(dir, &qname);
	199	if (child) {
	200	inode = proc_sys_make_inode(dir->d_sb, head, table);
	201	if (!inode) {
	202	dput(child);
	203	return -ENOMEM;
	204	} else {
fb045adb	205	d_set_d_op(child, &proc_sys_dentry_operations);
9043476f	206	d_add(child, inode);
77b14db5	207	}
9043476f AV	208	} else {
9043476f AV	209	return -ENOMEM;
77b14db5 EB	210	}
77b14db5 EB	211	}
77b14db5	212	inode = child->d_inode;
9043476f AV	213	ino = inode->i_ino;
9043476f AV	214	type = inode->i_mode >> 12;
77b14db5	215	dput(child);
9043476f AV	216	return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
	217	}
	218
	219	static int scan(struct ctl_table_header head, ctl_table table,
	220	unsigned long pos, struct file file,
	221	void *dirent, filldir_t filldir)
	222	{
	223
2315ffa0	224	for (; table->procname; table++, (*pos)++) {
9043476f AV	225	int res;
	226
	227	/* Can't do anything without a proc name */
	228	if (!table->procname)
	229	continue;
	230
	231	if (*pos < file->f_pos)
	232	continue;
	233
	234	res = proc_sys_fill_cache(file, dirent, filldir, head, table);
	235	if (res)
	236	return res;
	237
	238	file->f_pos = *pos + 1;
	239	}
	240	return 0;
77b14db5 EB	241	}
	242
	243	static int proc_sys_readdir(struct file filp, void dirent, filldir_t filldir)
	244	{
9043476f	245	struct dentry *dentry = filp->f_path.dentry;
77b14db5	246	struct inode *inode = dentry->d_inode;
9043476f AV	247	struct ctl_table_header *head = grab_header(inode);
	248	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
	249	struct ctl_table_header *h = NULL;
77b14db5	250	unsigned long pos;
9043476f AV	251	int ret = -EINVAL;
	252
	253	if (IS_ERR(head))
	254	return PTR_ERR(head);
77b14db5	255
9043476f AV	256	if (table && !table->child) {
9043476f AV	257	WARN_ON(1);
77b14db5	258	goto out;
9043476f AV	259	}
	260
	261	table = table ? table->child : head->ctl_table;
77b14db5 EB	262
	263	ret = 0;
	264	/* Avoid a switch here: arm builds fail with missing __cmpdi2 */
	265	if (filp->f_pos == 0) {
	266	if (filldir(dirent, ".", 1, filp->f_pos,
	267	inode->i_ino, DT_DIR) < 0)
	268	goto out;
	269	filp->f_pos++;
	270	}
	271	if (filp->f_pos == 1) {
	272	if (filldir(dirent, "..", 2, filp->f_pos,
	273	parent_ino(dentry), DT_DIR) < 0)
	274	goto out;
	275	filp->f_pos++;
	276	}
	277	pos = 2;
	278
9043476f AV	279	ret = scan(head, table, &pos, filp, dirent, filldir);
	280	if (ret)
	281	goto out;
77b14db5	282
9043476f AV	283	for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
9043476f AV	284	if (h->attached_to != table)
77b14db5	285	continue;
9043476f AV	286	ret = scan(h, h->attached_by, &pos, filp, dirent, filldir);
	287	if (ret) {
	288	sysctl_head_finish(h);
	289	break;
77b14db5 EB	290	}
	291	}
	292	ret = 1;
	293	out:
	294	sysctl_head_finish(head);
	295	return ret;
	296	}
	297
b74c79e9	298	static int proc_sys_permission(struct inode *inode, int mask,unsigned int flags)
77b14db5 EB	299	{
	300	/*
	301	* sysctl entries that are not writeable,
	302	* are _NOT_ writeable, capabilities or not.
	303	*/
f696a365 MS	304	struct ctl_table_header *head;
f696a365 MS	305	struct ctl_table *table;
77b14db5 EB	306	int error;
77b14db5 EB	307
b74c79e9 NP	308	if (flags & IPERM_FLAG_RCU)
	309	return -ECHILD;
	310
f696a365 MS	311	/* Executable files are not allowed under /proc/sys/ */
	312	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
	313	return -EACCES;
	314
	315	head = grab_header(inode);
9043476f AV	316	if (IS_ERR(head))
9043476f AV	317	return PTR_ERR(head);
77b14db5	318
f696a365	319	table = PROC_I(inode)->sysctl_entry;
9043476f AV	320	if (!table) /* global root - r-xr-xr-x */
	321	error = mask & MAY_WRITE ? -EACCES : 0;
	322	else /* Use the permissions on the sysctl table entry */
	323	error = sysctl_perm(head->root, table, mask);
77b14db5	324
77b14db5 EB	325	sysctl_head_finish(head);
	326	return error;
	327	}
	328
	329	static int proc_sys_setattr(struct dentry dentry, struct iattr attr)
	330	{
	331	struct inode *inode = dentry->d_inode;
	332	int error;
	333
	334	if (attr->ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID))
	335	return -EPERM;
	336
	337	error = inode_change_ok(inode, attr);
1025774c CH	338	if (error)
	339	return error;
	340
	341	if ((attr->ia_valid & ATTR_SIZE) &&
	342	attr->ia_size != i_size_read(inode)) {
	343	error = vmtruncate(inode, attr->ia_size);
	344	if (error)
	345	return error;
	346	}
77b14db5	347
1025774c CH	348	setattr_copy(inode, attr);
	349	mark_inode_dirty(inode);
	350	return 0;
77b14db5 EB	351	}
77b14db5 EB	352
9043476f AV	353	static int proc_sys_getattr(struct vfsmount mnt, struct dentry dentry, struct kstat *stat)
	354	{
	355	struct inode *inode = dentry->d_inode;
	356	struct ctl_table_header *head = grab_header(inode);
	357	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
	358
	359	if (IS_ERR(head))
	360	return PTR_ERR(head);
	361
	362	generic_fillattr(inode, stat);
	363	if (table)
	364	stat->mode = (stat->mode & S_IFMT) \| table->mode;
	365
	366	sysctl_head_finish(head);
	367	return 0;
	368	}
	369
77b14db5 EB	370	static const struct file_operations proc_sys_file_operations = {
	371	.read = proc_sys_read,
	372	.write = proc_sys_write,
6038f373	373	.llseek = default_llseek,
9043476f AV	374	};
	375
	376	static const struct file_operations proc_sys_dir_file_operations = {
77b14db5	377	.readdir = proc_sys_readdir,
3222a3e5	378	.llseek = generic_file_llseek,
77b14db5 EB	379	};
77b14db5 EB	380
03a44825	381	static const struct inode_operations proc_sys_inode_operations = {
9043476f AV	382	.permission = proc_sys_permission,
	383	.setattr = proc_sys_setattr,
	384	.getattr = proc_sys_getattr,
	385	};
	386
	387	static const struct inode_operations proc_sys_dir_operations = {
77b14db5 EB	388	.lookup = proc_sys_lookup,
	389	.permission = proc_sys_permission,
	390	.setattr = proc_sys_setattr,
9043476f	391	.getattr = proc_sys_getattr,
77b14db5 EB	392	};
	393
	394	static int proc_sys_revalidate(struct dentry dentry, struct nameidata nd)
	395	{
34286d66 NP	396	if (nd->flags & LOOKUP_RCU)
34286d66 NP	397	return -ECHILD;
9043476f AV	398	return !PROC_I(dentry->d_inode)->sysctl->unregistering;
	399	}
	400
fe15ce44	401	static int proc_sys_delete(const struct dentry *dentry)
9043476f AV	402	{
	403	return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
	404	}
	405
621e155a NP	406	static int proc_sys_compare(const struct dentry *parent,
	407	const struct inode *pinode,
	408	const struct dentry dentry, const struct inode inode,
	409	unsigned int len, const char str, const struct qstr name)
9043476f	410	{
31e6b01f NP	411	/* Although proc doesn't have negative dentries, rcu-walk means
	412	* that inode here can be NULL */
	413	if (!inode)
	414	return 0;
621e155a	415	if (name->len != len)
9043476f	416	return 1;
621e155a	417	if (memcmp(name->name, str, len))
9043476f	418	return 1;
621e155a	419	return !sysctl_is_seen(PROC_I(inode)->sysctl);
77b14db5 EB	420	}
77b14db5 EB	421
d72f71eb	422	static const struct dentry_operations proc_sys_dentry_operations = {
77b14db5	423	.d_revalidate = proc_sys_revalidate,
9043476f AV	424	.d_delete = proc_sys_delete,
9043476f AV	425	.d_compare = proc_sys_compare,
77b14db5 EB	426	};
77b14db5 EB	427
1e0edd3f	428	int __init proc_sys_init(void)
77b14db5	429	{
e1675231 AD	430	struct proc_dir_entry *proc_sys_root;
e1675231 AD	431
77b14db5	432	proc_sys_root = proc_mkdir("sys", NULL);
9043476f AV	433	proc_sys_root->proc_iops = &proc_sys_dir_operations;
9043476f AV	434	proc_sys_root->proc_fops = &proc_sys_dir_file_operations;
77b14db5 EB	435	proc_sys_root->nlink = 0;
	436	return 0;
	437	}