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