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 *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
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;
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);
71 out:
72 up_read(&task->signal->exec_update_lock);
73 out_put_task:
74 put_task_struct(task);
75 return ERR_PTR(error);
76 }
77
proc_ns_readlink(struct dentry * dentry,char __user * buffer,int buflen)78 static 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);
101 out_put_task:
102 put_task_struct(task);
103 return res;
104 }
105
106 static 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
proc_ns_instantiate(struct dentry * dentry,struct task_struct * task,const void * ptr)112 static 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
proc_ns_dir_readdir(struct file * file,struct dir_context * ctx)131 static 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 }
153 out:
154 put_task_struct(task);
155 return 0;
156 }
157
158 const 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
proc_ns_dir_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)164 static 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);
186 out:
187 put_task_struct(task);
188 out_no_task:
189 return res;
190 }
191
192 const struct inode_operations proc_ns_dir_inode_operations = {
193 .lookup = proc_ns_dir_lookup,
194 .getattr = pid_getattr,
195 .setattr = proc_nochmod_setattr,
196 };
197