/* * /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_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; 	/* 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){	struct ctl_table_header *head;	/* Although proc doesn't have negative dentries, rcu-walk means	 * that inode here can be NULL */	/* AV: can it, indeed? */	if (!inode)		return 1;	if (name->len != len)		return 1;	if (memcmp(name->name, str, len))		return 1;	head = rcu_dereference(PROC_I(inode)->sysctl);	return !head || !sysctl_is_seen(head);} 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;}