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 #ifdef CONFIG_TIME_NS
37 &timens_operations,
38 &timens_for_children_operations,
39 #endif
40 };
41
proc_ns_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * done)42 static 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);
66 out:
67 put_task_struct(task);
68 return ERR_PTR(error);
69 }
70
proc_ns_readlink(struct dentry * dentry,char __user * buffer,int buflen)71 static 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
92 static 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
proc_ns_instantiate(struct dentry * dentry,struct task_struct * task,const void * ptr)98 static 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
proc_ns_dir_readdir(struct file * file,struct dir_context * ctx)117 static 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 **entry, **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 }
139 out:
140 put_task_struct(task);
141 return 0;
142 }
143
144 const 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
proc_ns_dir_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)150 static 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 **entry, **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);
172 out:
173 put_task_struct(task);
174 out_no_task:
175 return res;
176 }
177
178 const struct inode_operations proc_ns_dir_inode_operations = {
179 .lookup = proc_ns_dir_lookup,
180 .getattr = pid_getattr,
181 .setattr = proc_setattr,
182 };
183