1#include <linux/sched.h>
 2#include <linux/slab.h>
 3#include <linux/pid_namespace.h>
 4#include "internal.h"
 5
 6/*
 7 * /proc/self:
 8 */
 9static const char *proc_self_get_link(struct dentry *dentry,
10				      struct inode *inode,
11				      struct delayed_call *done)
12{
13	struct pid_namespace *ns = inode->i_sb->s_fs_info;
14	pid_t tgid = task_tgid_nr_ns(current, ns);
15	char *name;
16
17	if (!tgid)
18		return ERR_PTR(-ENOENT);
19	/* 11 for max length of signed int in decimal + NULL term */
20	name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC);
21	if (unlikely(!name))
22		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
23	sprintf(name, "%d", tgid);
24	set_delayed_call(done, kfree_link, name);
25	return name;
26}
27
28static const struct inode_operations proc_self_inode_operations = {
29	.get_link	= proc_self_get_link,
30};
31
32static unsigned self_inum;
33
34int proc_setup_self(struct super_block *s)
35{
36	struct inode *root_inode = d_inode(s->s_root);
37	struct pid_namespace *ns = s->s_fs_info;
38	struct dentry *self;
39	
40	inode_lock(root_inode);
41	self = d_alloc_name(s->s_root, "self");
42	if (self) {
43		struct inode *inode = new_inode_pseudo(s);
44		if (inode) {
45			inode->i_ino = self_inum;
46			inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
47			inode->i_mode = S_IFLNK | S_IRWXUGO;
48			inode->i_uid = GLOBAL_ROOT_UID;
49			inode->i_gid = GLOBAL_ROOT_GID;
50			inode->i_op = &proc_self_inode_operations;
51			d_add(self, inode);
52		} else {
53			dput(self);
54			self = ERR_PTR(-ENOMEM);
55		}
56	} else {
57		self = ERR_PTR(-ENOMEM);
58	}
59	inode_unlock(root_inode);
60	if (IS_ERR(self)) {
61		pr_err("proc_fill_super: can't allocate /proc/self\n");
62		return PTR_ERR(self);
63	}
64	ns->proc_self = self;
65	return 0;
66}
67
68void __init proc_self_init(void)
69{
70	proc_alloc_inum(&self_inum);
71}