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(error: -ECHILD);
53
54 task = get_proc_task(inode);
55 if (!task)
56 return ERR_PTR(error: -EACCES);
57
58 if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
59 goto out;
60
61 error = ns_get_path(path: &ns_path, task, ns_ops);
62 if (error)
63 goto out;
64
65 error = nd_jump_link(path: &ns_path);
66out:
67 put_task_struct(t: 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(buf: name, size: sizeof(name), task, ns_ops);
85 if (res >= 0)
86 res = readlink_copy(buffer, buflen, name, strlen(name));
87 }
88 put_task_struct(t: 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(error: -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(inode: file_inode(f: 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(t: 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(inode: 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(error: -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(p: dentry->d_name.name, q: (*entry)->name, size: len))
166 break;
167 }
168 if (entry == last)
169 goto out;
170
171 res = proc_ns_instantiate(dentry, task, ptr: *entry);
172out:
173 put_task_struct(t: 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};
183

source code of linux/fs/proc/namespaces.c