1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  linux/fs/proc/net.c
4 *
5 *  Copyright (C) 2007
6 *
7 *  Author: Eric Biederman <ebiederm@xmission.com>
8 *
9 *  proc net directory handling functions
10 */
11#include <linux/errno.h>
12#include <linux/time.h>
13#include <linux/proc_fs.h>
14#include <linux/stat.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/sched.h>
18#include <linux/sched/task.h>
19#include <linux/module.h>
20#include <linux/bitops.h>
21#include <linux/mount.h>
22#include <linux/nsproxy.h>
23#include <linux/uidgid.h>
24#include <net/net_namespace.h>
25#include <linux/seq_file.h>
26
27#include "internal.h"
28
29static inline struct net *PDE_NET(struct proc_dir_entry *pde)
30{
31	return pde->parent->data;
32}
33
34static struct net *get_proc_net(const struct inode *inode)
35{
36	return maybe_get_net(PDE_NET(PDE(inode)));
37}
38
39static int seq_open_net(struct inode *inode, struct file *file)
40{
41	unsigned int state_size = PDE(inode)->state_size;
42	struct seq_net_private *p;
43	struct net *net;
44
45	WARN_ON_ONCE(state_size < sizeof(*p));
46
47	if (file->f_mode & FMODE_WRITE && !PDE(inode)->write)
48		return -EACCES;
49
50	net = get_proc_net(inode);
51	if (!net)
52		return -ENXIO;
53
54	p = __seq_open_private(file, PDE(inode)->seq_ops, state_size);
55	if (!p) {
56		put_net(net);
57		return -ENOMEM;
58	}
59#ifdef CONFIG_NET_NS
60	p->net = net;
61	netns_tracker_alloc(net, &p->ns_tracker, GFP_KERNEL);
62#endif
63	return 0;
64}
65
66static void seq_file_net_put_net(struct seq_file *seq)
67{
68#ifdef CONFIG_NET_NS
69	struct seq_net_private *priv = seq->private;
70
71	put_net_track(priv->net, &priv->ns_tracker);
72#else
73	put_net(&init_net);
74#endif
75}
76
77static int seq_release_net(struct inode *ino, struct file *f)
78{
79	struct seq_file *seq = f->private_data;
80
81	seq_file_net_put_net(seq);
82	seq_release_private(ino, f);
83	return 0;
84}
85
86static const struct proc_ops proc_net_seq_ops = {
87	.proc_open	= seq_open_net,
88	.proc_read	= seq_read,
89	.proc_write	= proc_simple_write,
90	.proc_lseek	= seq_lseek,
91	.proc_release	= seq_release_net,
92};
93
94int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)
95{
96#ifdef CONFIG_NET_NS
97	struct seq_net_private *p = priv_data;
98
99	p->net = get_net_track(current->nsproxy->net_ns, &p->ns_tracker,
100			       GFP_KERNEL);
101#endif
102	return 0;
103}
104
105void bpf_iter_fini_seq_net(void *priv_data)
106{
107#ifdef CONFIG_NET_NS
108	struct seq_net_private *p = priv_data;
109
110	put_net_track(p->net, &p->ns_tracker);
111#endif
112}
113
114struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
115		struct proc_dir_entry *parent, const struct seq_operations *ops,
116		unsigned int state_size, void *data)
117{
118	struct proc_dir_entry *p;
119
120	p = proc_create_reg(name, mode, &parent, data);
121	if (!p)
122		return NULL;
123	pde_force_lookup(p);
124	p->proc_ops = &proc_net_seq_ops;
125	p->seq_ops = ops;
126	p->state_size = state_size;
127	return proc_register(parent, p);
128}
129EXPORT_SYMBOL_GPL(proc_create_net_data);
130
131/**
132 * proc_create_net_data_write - Create a writable net_ns-specific proc file
133 * @name: The name of the file.
134 * @mode: The file's access mode.
135 * @parent: The parent directory in which to create.
136 * @ops: The seq_file ops with which to read the file.
137 * @write: The write method with which to 'modify' the file.
138 * @state_size: The size of the per-file private state to allocate.
139 * @data: Data for retrieval by pde_data().
140 *
141 * Create a network namespaced proc file in the @parent directory with the
142 * specified @name and @mode that allows reading of a file that displays a
143 * series of elements and also provides for the file accepting writes that have
144 * some arbitrary effect.
145 *
146 * The functions in the @ops table are used to iterate over items to be
147 * presented and extract the readable content using the seq_file interface.
148 *
149 * The @write function is called with the data copied into a kernel space
150 * scratch buffer and has a NUL appended for convenience.  The buffer may be
151 * modified by the @write function.  @write should return 0 on success.
152 *
153 * The @data value is accessible from the @show and @write functions by calling
154 * pde_data() on the file inode.  The network namespace must be accessed by
155 * calling seq_file_net() on the seq_file struct.
156 */
157struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
158						  struct proc_dir_entry *parent,
159						  const struct seq_operations *ops,
160						  proc_write_t write,
161						  unsigned int state_size, void *data)
162{
163	struct proc_dir_entry *p;
164
165	p = proc_create_reg(name, mode, &parent, data);
166	if (!p)
167		return NULL;
168	pde_force_lookup(p);
169	p->proc_ops = &proc_net_seq_ops;
170	p->seq_ops = ops;
171	p->state_size = state_size;
172	p->write = write;
173	return proc_register(parent, p);
174}
175EXPORT_SYMBOL_GPL(proc_create_net_data_write);
176
177static int single_open_net(struct inode *inode, struct file *file)
178{
179	struct proc_dir_entry *de = PDE(inode);
180	struct net *net;
181	int err;
182
183	net = get_proc_net(inode);
184	if (!net)
185		return -ENXIO;
186
187	err = single_open(file, de->single_show, net);
188	if (err)
189		put_net(net);
190	return err;
191}
192
193static int single_release_net(struct inode *ino, struct file *f)
194{
195	struct seq_file *seq = f->private_data;
196	put_net(seq->private);
197	return single_release(ino, f);
198}
199
200static const struct proc_ops proc_net_single_ops = {
201	.proc_open	= single_open_net,
202	.proc_read	= seq_read,
203	.proc_write	= proc_simple_write,
204	.proc_lseek	= seq_lseek,
205	.proc_release	= single_release_net,
206};
207
208struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
209		struct proc_dir_entry *parent,
210		int (*show)(struct seq_file *, void *), void *data)
211{
212	struct proc_dir_entry *p;
213
214	p = proc_create_reg(name, mode, &parent, data);
215	if (!p)
216		return NULL;
217	pde_force_lookup(p);
218	p->proc_ops = &proc_net_single_ops;
219	p->single_show = show;
220	return proc_register(parent, p);
221}
222EXPORT_SYMBOL_GPL(proc_create_net_single);
223
224/**
225 * proc_create_net_single_write - Create a writable net_ns-specific proc file
226 * @name: The name of the file.
227 * @mode: The file's access mode.
228 * @parent: The parent directory in which to create.
229 * @show: The seqfile show method with which to read the file.
230 * @write: The write method with which to 'modify' the file.
231 * @data: Data for retrieval by pde_data().
232 *
233 * Create a network-namespaced proc file in the @parent directory with the
234 * specified @name and @mode that allows reading of a file that displays a
235 * single element rather than a series and also provides for the file accepting
236 * writes that have some arbitrary effect.
237 *
238 * The @show function is called to extract the readable content via the
239 * seq_file interface.
240 *
241 * The @write function is called with the data copied into a kernel space
242 * scratch buffer and has a NUL appended for convenience.  The buffer may be
243 * modified by the @write function.  @write should return 0 on success.
244 *
245 * The @data value is accessible from the @show and @write functions by calling
246 * pde_data() on the file inode.  The network namespace must be accessed by
247 * calling seq_file_single_net() on the seq_file struct.
248 */
249struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
250						    struct proc_dir_entry *parent,
251						    int (*show)(struct seq_file *, void *),
252						    proc_write_t write,
253						    void *data)
254{
255	struct proc_dir_entry *p;
256
257	p = proc_create_reg(name, mode, &parent, data);
258	if (!p)
259		return NULL;
260	pde_force_lookup(p);
261	p->proc_ops = &proc_net_single_ops;
262	p->single_show = show;
263	p->write = write;
264	return proc_register(parent, p);
265}
266EXPORT_SYMBOL_GPL(proc_create_net_single_write);
267
268static struct net *get_proc_task_net(struct inode *dir)
269{
270	struct task_struct *task;
271	struct nsproxy *ns;
272	struct net *net = NULL;
273
274	rcu_read_lock();
275	task = pid_task(proc_pid(dir), PIDTYPE_PID);
276	if (task != NULL) {
277		task_lock(task);
278		ns = task->nsproxy;
279		if (ns != NULL)
280			net = get_net(ns->net_ns);
281		task_unlock(task);
282	}
283	rcu_read_unlock();
284
285	return net;
286}
287
288static struct dentry *proc_tgid_net_lookup(struct inode *dir,
289		struct dentry *dentry, unsigned int flags)
290{
291	struct dentry *de;
292	struct net *net;
293
294	de = ERR_PTR(-ENOENT);
295	net = get_proc_task_net(dir);
296	if (net != NULL) {
297		de = proc_lookup_de(dir, dentry, net->proc_net);
298		put_net(net);
299	}
300	return de;
301}
302
303static int proc_tgid_net_getattr(struct mnt_idmap *idmap,
304				 const struct path *path, struct kstat *stat,
305				 u32 request_mask, unsigned int query_flags)
306{
307	struct inode *inode = d_inode(path->dentry);
308	struct net *net;
309
310	net = get_proc_task_net(inode);
311
312	generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
313
314	if (net != NULL) {
315		stat->nlink = net->proc_net->nlink;
316		put_net(net);
317	}
318
319	return 0;
320}
321
322const struct inode_operations proc_net_inode_operations = {
323	.lookup		= proc_tgid_net_lookup,
324	.getattr	= proc_tgid_net_getattr,
325	.setattr        = proc_setattr,
326};
327
328static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)
329{
330	int ret;
331	struct net *net;
332
333	ret = -EINVAL;
334	net = get_proc_task_net(file_inode(file));
335	if (net != NULL) {
336		ret = proc_readdir_de(file, ctx, net->proc_net);
337		put_net(net);
338	}
339	return ret;
340}
341
342const struct file_operations proc_net_operations = {
343	.llseek		= generic_file_llseek,
344	.read		= generic_read_dir,
345	.iterate_shared	= proc_tgid_net_readdir,
346};
347
348static __net_init int proc_net_ns_init(struct net *net)
349{
350	struct proc_dir_entry *netd, *net_statd;
351	kuid_t uid;
352	kgid_t gid;
353	int err;
354
355	/*
356	 * This PDE acts only as an anchor for /proc/${pid}/net hierarchy.
357	 * Corresponding inode (PDE(inode) == net->proc_net) is never
358	 * instantiated therefore blanket zeroing is fine.
359	 * net->proc_net_stat inode is instantiated normally.
360	 */
361	err = -ENOMEM;
362	netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
363	if (!netd)
364		goto out;
365
366	netd->subdir = RB_ROOT;
367	netd->data = net;
368	netd->nlink = 2;
369	netd->namelen = 3;
370	netd->parent = &proc_root;
371	netd->name = netd->inline_name;
372	memcpy(netd->name, "net", 4);
373
374	uid = make_kuid(net->user_ns, 0);
375	if (!uid_valid(uid))
376		uid = netd->uid;
377
378	gid = make_kgid(net->user_ns, 0);
379	if (!gid_valid(gid))
380		gid = netd->gid;
381
382	proc_set_user(netd, uid, gid);
383
384	/* Seed dentry revalidation for /proc/${pid}/net */
385	pde_force_lookup(netd);
386
387	err = -EEXIST;
388	net_statd = proc_net_mkdir(net, "stat", netd);
389	if (!net_statd)
390		goto free_net;
391
392	net->proc_net = netd;
393	net->proc_net_stat = net_statd;
394	return 0;
395
396free_net:
397	pde_free(netd);
398out:
399	return err;
400}
401
402static __net_exit void proc_net_ns_exit(struct net *net)
403{
404	remove_proc_entry("stat", net->proc_net);
405	pde_free(net->proc_net);
406}
407
408static struct pernet_operations __net_initdata proc_net_ns_ops = {
409	.init = proc_net_ns_init,
410	.exit = proc_net_ns_exit,
411};
412
413int __init proc_net_init(void)
414{
415	proc_symlink("net", NULL, "self/net");
416
417	return register_pernet_subsys(&proc_net_ns_ops);
418}
419