1// SPDX-License-Identifier: GPL-2.0
2#include <linux/proc_fs.h>
3#include <linux/nsproxy.h>
4#include <linux/ptrace.h>
5#include <linux/namei.h>
6#include <linux/file.h>
7#include <linux/utsname.h>
8#include <net/net_namespace.h>
9#include <linux/ipc_namespace.h>
10#include <linux/pid_namespace.h>
11#include <linux/user_namespace.h>
12#include "internal.h"
13
14
15static const struct proc_ns_operations *ns_entries[] = {
16#ifdef CONFIG_NET_NS
17	&netns_operations,
18#endif
19#ifdef CONFIG_UTS_NS
20	&utsns_operations,
21#endif
22#ifdef CONFIG_IPC_NS
23	&ipcns_operations,
24#endif
25#ifdef CONFIG_PID_NS
26	&pidns_operations,
27	&pidns_for_children_operations,
28#endif
29#ifdef CONFIG_USER_NS
30	&userns_operations,
31#endif
32	&mntns_operations,
33#ifdef CONFIG_CGROUPS
34	&cgroupns_operations,
35#endif
36#ifdef CONFIG_TIME_NS
37	&timens_operations,
38	&timens_for_children_operations,
39#endif
40};
41
42static const char *proc_ns_get_link(struct dentry *dentry,
43				    struct inode *inode,
44				    struct delayed_call *done)
45{
46	const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
47	struct task_struct *task;
48	struct path ns_path;
49	int error = -EACCES;
50
51	if (!dentry)
52		return ERR_PTR(-ECHILD);
53
54	task = get_proc_task(inode);
55	if (!task)
56		return ERR_PTR(-EACCES);
57
58	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
59		goto out;
60
61	error = ns_get_path(&ns_path, task, ns_ops);
62	if (error)
63		goto out;
64
65	error = nd_jump_link(&ns_path);
66out:
67	put_task_struct(task);
68	return ERR_PTR(error);
69}
70
71static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
72{
73	struct inode *inode = d_inode(dentry);
74	const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
75	struct task_struct *task;
76	char name[50];
77	int res = -EACCES;
78
79	task = get_proc_task(inode);
80	if (!task)
81		return res;
82
83	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
84		res = ns_get_name(name, sizeof(name), task, ns_ops);
85		if (res >= 0)
86			res = readlink_copy(buffer, buflen, name);
87	}
88	put_task_struct(task);
89	return res;
90}
91
92static const struct inode_operations proc_ns_link_inode_operations = {
93	.readlink	= proc_ns_readlink,
94	.get_link	= proc_ns_get_link,
95	.setattr	= proc_setattr,
96};
97
98static struct dentry *proc_ns_instantiate(struct dentry *dentry,
99	struct task_struct *task, const void *ptr)
100{
101	const struct proc_ns_operations *ns_ops = ptr;
102	struct inode *inode;
103	struct proc_inode *ei;
104
105	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK | S_IRWXUGO);
106	if (!inode)
107		return ERR_PTR(-ENOENT);
108
109	ei = PROC_I(inode);
110	inode->i_op = &proc_ns_link_inode_operations;
111	ei->ns_ops = ns_ops;
112	pid_update_inode(task, inode);
113
114	d_set_d_op(dentry, &pid_dentry_operations);
115	return d_splice_alias(inode, dentry);
116}
117
118static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
119{
120	struct task_struct *task = get_proc_task(file_inode(file));
121	const struct proc_ns_operations **entry, **last;
122
123	if (!task)
124		return -ENOENT;
125
126	if (!dir_emit_dots(file, ctx))
127		goto out;
128	if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
129		goto out;
130	entry = ns_entries + (ctx->pos - 2);
131	last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
132	while (entry <= last) {
133		const struct proc_ns_operations *ops = *entry;
134		if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
135				     proc_ns_instantiate, task, ops))
136			break;
137		ctx->pos++;
138		entry++;
139	}
140out:
141	put_task_struct(task);
142	return 0;
143}
144
145const struct file_operations proc_ns_dir_operations = {
146	.read		= generic_read_dir,
147	.iterate_shared	= proc_ns_dir_readdir,
148	.llseek		= generic_file_llseek,
149};
150
151static struct dentry *proc_ns_dir_lookup(struct inode *dir,
152				struct dentry *dentry, unsigned int flags)
153{
154	struct task_struct *task = get_proc_task(dir);
155	const struct proc_ns_operations **entry, **last;
156	unsigned int len = dentry->d_name.len;
157	struct dentry *res = ERR_PTR(-ENOENT);
158
159	if (!task)
160		goto out_no_task;
161
162	last = &ns_entries[ARRAY_SIZE(ns_entries)];
163	for (entry = ns_entries; entry < last; entry++) {
164		if (strlen((*entry)->name) != len)
165			continue;
166		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
167			break;
168	}
169	if (entry == last)
170		goto out;
171
172	res = proc_ns_instantiate(dentry, task, *entry);
173out:
174	put_task_struct(task);
175out_no_task:
176	return res;
177}
178
179const struct inode_operations proc_ns_dir_inode_operations = {
180	.lookup		= proc_ns_dir_lookup,
181	.getattr	= pid_getattr,
182	.setattr	= proc_setattr,
183};
184