GNU Linux-libre 4.19.211-gnu1
[releases.git] / fs / proc / 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
15 static const struct proc_ns_operations *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 };
37
38 static const char *proc_ns_get_link(struct dentry *dentry,
39                                     struct inode *inode,
40                                     struct delayed_call *done)
41 {
42         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
43         struct task_struct *task;
44         struct path ns_path;
45         void *error = ERR_PTR(-EACCES);
46
47         if (!dentry)
48                 return ERR_PTR(-ECHILD);
49
50         task = get_proc_task(inode);
51         if (!task)
52                 return error;
53
54         if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
55                 error = ns_get_path(&ns_path, task, ns_ops);
56                 if (!error)
57                         nd_jump_link(&ns_path);
58         }
59         put_task_struct(task);
60         return error;
61 }
62
63 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
64 {
65         struct inode *inode = d_inode(dentry);
66         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
67         struct task_struct *task;
68         char name[50];
69         int res = -EACCES;
70
71         task = get_proc_task(inode);
72         if (!task)
73                 return res;
74
75         if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
76                 res = ns_get_name(name, sizeof(name), task, ns_ops);
77                 if (res >= 0)
78                         res = readlink_copy(buffer, buflen, name);
79         }
80         put_task_struct(task);
81         return res;
82 }
83
84 static const struct inode_operations proc_ns_link_inode_operations = {
85         .readlink       = proc_ns_readlink,
86         .get_link       = proc_ns_get_link,
87         .setattr        = proc_setattr,
88 };
89
90 static struct dentry *proc_ns_instantiate(struct dentry *dentry,
91         struct task_struct *task, const void *ptr)
92 {
93         const struct proc_ns_operations *ns_ops = ptr;
94         struct inode *inode;
95         struct proc_inode *ei;
96
97         inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK | S_IRWXUGO);
98         if (!inode)
99                 return ERR_PTR(-ENOENT);
100
101         ei = PROC_I(inode);
102         inode->i_op = &proc_ns_link_inode_operations;
103         ei->ns_ops = ns_ops;
104         pid_update_inode(task, inode);
105
106         d_set_d_op(dentry, &pid_dentry_operations);
107         return d_splice_alias(inode, dentry);
108 }
109
110 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
111 {
112         struct task_struct *task = get_proc_task(file_inode(file));
113         const struct proc_ns_operations **entry, **last;
114
115         if (!task)
116                 return -ENOENT;
117
118         if (!dir_emit_dots(file, ctx))
119                 goto out;
120         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
121                 goto out;
122         entry = ns_entries + (ctx->pos - 2);
123         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
124         while (entry <= last) {
125                 const struct proc_ns_operations *ops = *entry;
126                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
127                                      proc_ns_instantiate, task, ops))
128                         break;
129                 ctx->pos++;
130                 entry++;
131         }
132 out:
133         put_task_struct(task);
134         return 0;
135 }
136
137 const struct file_operations proc_ns_dir_operations = {
138         .read           = generic_read_dir,
139         .iterate_shared = proc_ns_dir_readdir,
140         .llseek         = generic_file_llseek,
141 };
142
143 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
144                                 struct dentry *dentry, unsigned int flags)
145 {
146         struct task_struct *task = get_proc_task(dir);
147         const struct proc_ns_operations **entry, **last;
148         unsigned int len = dentry->d_name.len;
149         struct dentry *res = ERR_PTR(-ENOENT);
150
151         if (!task)
152                 goto out_no_task;
153
154         last = &ns_entries[ARRAY_SIZE(ns_entries)];
155         for (entry = ns_entries; entry < last; entry++) {
156                 if (strlen((*entry)->name) != len)
157                         continue;
158                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
159                         break;
160         }
161         if (entry == last)
162                 goto out;
163
164         res = proc_ns_instantiate(dentry, task, *entry);
165 out:
166         put_task_struct(task);
167 out_no_task:
168         return res;
169 }
170
171 const struct inode_operations proc_ns_dir_inode_operations = {
172         .lookup         = proc_ns_dir_lookup,
173         .getattr        = pid_getattr,
174         .setattr        = proc_setattr,
175 };