#include <linux/sched.h>#include <linux/namei.h>#include <linux/slab.h>#include <linux/pid_namespace.h>#include "internal.h" /* * /proc/self: */static int proc_self_readlink(struct dentry *dentry, char __user *buffer,			      int buflen){	struct pid_namespace *ns = dentry->d_sb->s_fs_info;	pid_t tgid = task_tgid_nr_ns(current, ns);	char tmp[PROC_NUMBUF];	if (!tgid)		return -ENOENT;	sprintf(tmp, "%d", tgid);	return vfs_readlink(dentry,buffer,buflen,tmp);} static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd){	struct pid_namespace *ns = dentry->d_sb->s_fs_info;	pid_t tgid = task_tgid_nr_ns(current, ns);	char *name = ERR_PTR(-ENOENT);	if (tgid) {		/* 11 for max length of signed int in decimal + NULL term */		name = kmalloc(12, GFP_KERNEL);		if (!name)			name = ERR_PTR(-ENOMEM);		else			sprintf(name, "%d", tgid);	}	nd_set_link(nd, name);	return NULL;} static const struct inode_operations proc_self_inode_operations = {	.readlink	= proc_self_readlink,	.follow_link	= proc_self_follow_link,	.put_link	= kfree_put_link,}; static unsigned self_inum; int proc_setup_self(struct super_block *s){	struct inode *root_inode = s->s_root->d_inode;	struct pid_namespace *ns = s->s_fs_info;	struct dentry *self;		mutex_lock(&root_inode->i_mutex);	self = d_alloc_name(s->s_root, "self");	if (self) {		struct inode *inode = new_inode_pseudo(s);		if (inode) {			inode->i_ino = self_inum;			inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;			inode->i_mode = S_IFLNK | S_IRWXUGO;			inode->i_uid = GLOBAL_ROOT_UID;			inode->i_gid = GLOBAL_ROOT_GID;			inode->i_op = &proc_self_inode_operations;			d_add(self, inode);		} else {			dput(self);			self = ERR_PTR(-ENOMEM);		}	} else {		self = ERR_PTR(-ENOMEM);	}	mutex_unlock(&root_inode->i_mutex);	if (IS_ERR(self)) {		pr_err("proc_fill_super: can't allocate /proc/self\n");		return PTR_ERR(self);	}	ns->proc_self = self;	return 0;} void __init proc_self_init(void){	proc_alloc_inum(&self_inum);}