namespaces.c

  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 *const 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, strlen(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	return d_splice_alias_ops(inode, dentry, &pid_dentry_operations);
115}
116
117static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
118{
119	struct task_struct *task = get_proc_task(file_inode(file));
120	const struct proc_ns_operations *const *entry, *const *last;
121
122	if (!task)
123		return -ENOENT;
124
125	if (!dir_emit_dots(file, ctx))
126		goto out;
127	if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
128		goto out;
129	entry = ns_entries + (ctx->pos - 2);
130	last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
131	while (entry <= last) {
132		const struct proc_ns_operations *ops = *entry;
133		if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
134				     proc_ns_instantiate, task, ops))
135			break;
136		ctx->pos++;
137		entry++;
138	}
139out:
140	put_task_struct(task);
141	return 0;
142}
143
144const struct file_operations proc_ns_dir_operations = {
145	.read		= generic_read_dir,
146	.iterate_shared	= proc_ns_dir_readdir,
147	.llseek		= generic_file_llseek,
148};
149
150static struct dentry *proc_ns_dir_lookup(struct inode *dir,
151				struct dentry *dentry, unsigned int flags)
152{
153	struct task_struct *task = get_proc_task(dir);
154	const struct proc_ns_operations *const *entry, *const *last;
155	unsigned int len = dentry->d_name.len;
156	struct dentry *res = ERR_PTR(-ENOENT);
157
158	if (!task)
159		goto out_no_task;
160
161	last = &ns_entries[ARRAY_SIZE(ns_entries)];
162	for (entry = ns_entries; entry < last; entry++) {
163		if (strlen((*entry)->name) != len)
164			continue;
165		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
166			break;
167	}
168	if (entry == last)
169		goto out;
170
171	res = proc_ns_instantiate(dentry, task, *entry);
172out:
173	put_task_struct(task);
174out_no_task:
175	return res;
176}
177
178const struct inode_operations proc_ns_dir_inode_operations = {
179	.lookup		= proc_ns_dir_lookup,
180	.getattr	= pid_getattr,
181	.setattr	= proc_setattr,
182};