1#include <linux/sched.h>
 2#include <linux/slab.h>
 3#include <linux/pid_namespace.h>
 4#include "internal.h"
 5
 6/*
 7 * /proc/thread_self:
 8 */
 9static int proc_thread_self_readlink(struct dentry *dentry, char __user *buffer,
10			      int buflen)
11{
12	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
13	pid_t tgid = task_tgid_nr_ns(current, ns);
14	pid_t pid = task_pid_nr_ns(current, ns);
15	char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF];
16	if (!pid)
17		return -ENOENT;
18	sprintf(tmp, "%d/task/%d", tgid, pid);
19	return readlink_copy(buffer, buflen, tmp);
20}
21
22static const char *proc_thread_self_get_link(struct dentry *dentry,
23					     struct inode *inode,
24					     struct delayed_call *done)
25{
26	struct pid_namespace *ns = inode->i_sb->s_fs_info;
27	pid_t tgid = task_tgid_nr_ns(current, ns);
28	pid_t pid = task_pid_nr_ns(current, ns);
29	char *name;
30
31	if (!pid)
32		return ERR_PTR(-ENOENT);
33	name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF,
34				dentry ? GFP_KERNEL : GFP_ATOMIC);
35	if (unlikely(!name))
36		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
37	sprintf(name, "%d/task/%d", tgid, pid);
38	set_delayed_call(done, kfree_link, name);
39	return name;
40}
41
42static const struct inode_operations proc_thread_self_inode_operations = {
43	.readlink	= proc_thread_self_readlink,
44	.get_link	= proc_thread_self_get_link,
45};
46
47static unsigned thread_self_inum;
48
49int proc_setup_thread_self(struct super_block *s)
50{
51	struct inode *root_inode = d_inode(s->s_root);
52	struct pid_namespace *ns = s->s_fs_info;
53	struct dentry *thread_self;
 
54
55	inode_lock(root_inode);
56	thread_self = d_alloc_name(s->s_root, "thread-self");
57	if (thread_self) {
58		struct inode *inode = new_inode_pseudo(s);
59		if (inode) {
60			inode->i_ino = thread_self_inum;
61			inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
62			inode->i_mode = S_IFLNK | S_IRWXUGO;
63			inode->i_uid = GLOBAL_ROOT_UID;
64			inode->i_gid = GLOBAL_ROOT_GID;
65			inode->i_op = &proc_thread_self_inode_operations;
66			d_add(thread_self, inode);
 
67		} else {
68			dput(thread_self);
69			thread_self = ERR_PTR(-ENOMEM);
70		}
71	} else {
72		thread_self = ERR_PTR(-ENOMEM);
73	}
74	inode_unlock(root_inode);
75	if (IS_ERR(thread_self)) {
76		pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
77		return PTR_ERR(thread_self);
78	}
79	ns->proc_thread_self = thread_self;
80	return 0;
 
81}
82
83void __init proc_thread_self_init(void)
84{
85	proc_alloc_inum(&thread_self_inum);
86}

 1// SPDX-License-Identifier: GPL-2.0
 2#include <linux/cache.h>
 3#include <linux/sched.h>
 4#include <linux/slab.h>
 5#include <linux/pid_namespace.h>
 6#include "internal.h"
 7
 8/*
 9 * /proc/thread_self:
10 */
 
 
 
 
 
 
 
 
 
 
 
 
 
11static const char *proc_thread_self_get_link(struct dentry *dentry,
12					     struct inode *inode,
13					     struct delayed_call *done)
14{
15	struct pid_namespace *ns = proc_pid_ns(inode->i_sb);
16	pid_t tgid = task_tgid_nr_ns(current, ns);
17	pid_t pid = task_pid_nr_ns(current, ns);
18	char *name;
19
20	if (!pid)
21		return ERR_PTR(-ENOENT);
22	name = kmalloc(10 + 6 + 10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
 
23	if (unlikely(!name))
24		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
25	sprintf(name, "%u/task/%u", tgid, pid);
26	set_delayed_call(done, kfree_link, name);
27	return name;
28}
29
30static const struct inode_operations proc_thread_self_inode_operations = {
 
31	.get_link	= proc_thread_self_get_link,
32};
33
34static unsigned thread_self_inum __ro_after_init;
35
36int proc_setup_thread_self(struct super_block *s)
37{
38	struct inode *root_inode = d_inode(s->s_root);
39	struct proc_fs_info *fs_info = proc_sb_info(s);
40	struct dentry *thread_self;
41	int ret = -ENOMEM;
42
43	inode_lock(root_inode);
44	thread_self = d_alloc_name(s->s_root, "thread-self");
45	if (thread_self) {
46		struct inode *inode = new_inode(s);
47		if (inode) {
48			inode->i_ino = thread_self_inum;
49			inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
50			inode->i_mode = S_IFLNK | S_IRWXUGO;
51			inode->i_uid = GLOBAL_ROOT_UID;
52			inode->i_gid = GLOBAL_ROOT_GID;
53			inode->i_op = &proc_thread_self_inode_operations;
54			d_add(thread_self, inode);
55			ret = 0;
56		} else {
57			dput(thread_self);
 
58		}
 
 
59	}
60	inode_unlock(root_inode);
61
62	if (ret)
63		pr_err("proc_fill_super: can't allocate /proc/thread-self\n");
64	else
65		fs_info->proc_thread_self = thread_self;
66
67	return ret;
68}
69
70void __init proc_thread_self_init(void)
71{
72	proc_alloc_inum(&thread_self_inum);
73}