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 
proc_ns_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * done)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 
proc_ns_readlink(struct dentry * dentry,char __user * buffer,int buflen)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 
proc_ns_instantiate(struct dentry * dentry,struct task_struct * task,const void * ptr)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 
proc_ns_dir_readdir(struct file * file,struct dir_context * ctx)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 
proc_ns_dir_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)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 };
176