xref: /openbmc/linux/fs/proc/namespaces.c (revision 769071ac)
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);
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 	d_set_d_op(dentry, &pid_dentry_operations);
115 	return d_splice_alias(inode, dentry);
116 }
117 
proc_ns_dir_readdir(struct file * file,struct dir_context * ctx)118 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
119 {
120 	struct task_struct *task = get_proc_task(file_inode(file));
121 	const struct proc_ns_operations **entry, **last;
122 
123 	if (!task)
124 		return -ENOENT;
125 
126 	if (!dir_emit_dots(file, ctx))
127 		goto out;
128 	if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
129 		goto out;
130 	entry = ns_entries + (ctx->pos - 2);
131 	last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
132 	while (entry <= last) {
133 		const struct proc_ns_operations *ops = *entry;
134 		if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
135 				     proc_ns_instantiate, task, ops))
136 			break;
137 		ctx->pos++;
138 		entry++;
139 	}
140 out:
141 	put_task_struct(task);
142 	return 0;
143 }
144 
145 const struct file_operations proc_ns_dir_operations = {
146 	.read		= generic_read_dir,
147 	.iterate_shared	= proc_ns_dir_readdir,
148 	.llseek		= generic_file_llseek,
149 };
150 
proc_ns_dir_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)151 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
152 				struct dentry *dentry, unsigned int flags)
153 {
154 	struct task_struct *task = get_proc_task(dir);
155 	const struct proc_ns_operations **entry, **last;
156 	unsigned int len = dentry->d_name.len;
157 	struct dentry *res = ERR_PTR(-ENOENT);
158 
159 	if (!task)
160 		goto out_no_task;
161 
162 	last = &ns_entries[ARRAY_SIZE(ns_entries)];
163 	for (entry = ns_entries; entry < last; entry++) {
164 		if (strlen((*entry)->name) != len)
165 			continue;
166 		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
167 			break;
168 	}
169 	if (entry == last)
170 		goto out;
171 
172 	res = proc_ns_instantiate(dentry, task, *entry);
173 out:
174 	put_task_struct(task);
175 out_no_task:
176 	return res;
177 }
178 
179 const struct inode_operations proc_ns_dir_inode_operations = {
180 	.lookup		= proc_ns_dir_lookup,
181 	.getattr	= pid_getattr,
182 	.setattr	= proc_setattr,
183 };
184