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196 lines · 4.6 KiB

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;
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 error = down_read_killable(&task->signal->exec_update_lock);
59 if (error)
60 goto out_put_task;
61
62 error = -EACCES;
63 if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
64 goto out;
65
66 error = ns_get_path(&ns_path, task, ns_ops);
67 if (error)
68 goto out;
69
70 error = nd_jump_link(&ns_path);
71out:
72 up_read(&task->signal->exec_update_lock);
73out_put_task:
74 put_task_struct(task);
75 return ERR_PTR(error);
76}
77
78static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
79{
80 struct inode *inode = d_inode(dentry);
81 const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
82 struct task_struct *task;
83 char name[50];
84 int res = -EACCES;
85
86 task = get_proc_task(inode);
87 if (!task)
88 return res;
89
90 res = down_read_killable(&task->signal->exec_update_lock);
91 if (res)
92 goto out_put_task;
93
94 res = -EACCES;
95 if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
96 res = ns_get_name(name, sizeof(name), task, ns_ops);
97 if (res >= 0)
98 res = readlink_copy(buffer, buflen, name, strlen(name));
99 }
100 up_read(&task->signal->exec_update_lock);
101out_put_task:
102 put_task_struct(task);
103 return res;
104}
105
106static const struct inode_operations proc_ns_link_inode_operations = {
107 .readlink = proc_ns_readlink,
108 .get_link = proc_ns_get_link,
109 .setattr = proc_nochmod_setattr,
110};
111
112static struct dentry *proc_ns_instantiate(struct dentry *dentry,
113 struct task_struct *task, const void *ptr)
114{
115 const struct proc_ns_operations *ns_ops = ptr;
116 struct inode *inode;
117 struct proc_inode *ei;
118
119 inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK | S_IRWXUGO);
120 if (!inode)
121 return ERR_PTR(-ENOENT);
122
123 ei = PROC_I(inode);
124 inode->i_op = &proc_ns_link_inode_operations;
125 ei->ns_ops = ns_ops;
126 pid_update_inode(task, inode);
127
128 return d_splice_alias_ops(inode, dentry, &pid_dentry_operations);
129}
130
131static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
132{
133 struct task_struct *task = get_proc_task(file_inode(file));
134 const struct proc_ns_operations *const *entry, *const *last;
135
136 if (!task)
137 return -ENOENT;
138
139 if (!dir_emit_dots(file, ctx))
140 goto out;
141 if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
142 goto out;
143 entry = ns_entries + (ctx->pos - 2);
144 last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
145 while (entry <= last) {
146 const struct proc_ns_operations *ops = *entry;
147 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
148 proc_ns_instantiate, task, ops))
149 break;
150 ctx->pos++;
151 entry++;
152 }
153out:
154 put_task_struct(task);
155 return 0;
156}
157
158const struct file_operations proc_ns_dir_operations = {
159 .read = generic_read_dir,
160 .iterate_shared = proc_ns_dir_readdir,
161 .llseek = generic_file_llseek,
162};
163
164static struct dentry *proc_ns_dir_lookup(struct inode *dir,
165 struct dentry *dentry, unsigned int flags)
166{
167 struct task_struct *task = get_proc_task(dir);
168 const struct proc_ns_operations *const *entry, *const *last;
169 unsigned int len = dentry->d_name.len;
170 struct dentry *res = ERR_PTR(-ENOENT);
171
172 if (!task)
173 goto out_no_task;
174
175 last = &ns_entries[ARRAY_SIZE(ns_entries)];
176 for (entry = ns_entries; entry < last; entry++) {
177 if (strlen((*entry)->name) != len)
178 continue;
179 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
180 break;
181 }
182 if (entry == last)
183 goto out;
184
185 res = proc_ns_instantiate(dentry, task, *entry);
186out:
187 put_task_struct(task);
188out_no_task:
189 return res;
190}
191
192const struct inode_operations proc_ns_dir_inode_operations = {
193 .lookup = proc_ns_dir_lookup,
194 .getattr = pid_getattr,
195 .setattr = proc_nochmod_setattr,
196};