1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
4 */
5
6 #include <linux/dcache.h>
7 #include <linux/security.h>
8
9 #include "ipe.h"
10 #include "fs.h"
11 #include "eval.h"
12 #include "policy.h"
13 #include "audit.h"
14
15 static struct dentry *root __ro_after_init;
16 struct dentry *policy_root __ro_after_init;
17
18 /**
19 * setaudit() - Write handler for the securityfs node, "ipe/success_audit"
20 * @f: Supplies a file structure representing the securityfs node.
21 * @data: Supplies a buffer passed to the write syscall.
22 * @len: Supplies the length of @data.
23 * @offset: unused.
24 *
25 * Return:
26 * * Length of buffer written - Success
27 * * %-EPERM - Insufficient permission
28 */
setaudit(struct file * f,const char __user * data,size_t len,loff_t * offset)29 static ssize_t setaudit(struct file *f, const char __user *data,
30 size_t len, loff_t *offset)
31 {
32 int rc = 0;
33 bool value;
34
35 if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
36 return -EPERM;
37
38 rc = kstrtobool_from_user(data, len, &value);
39 if (rc)
40 return rc;
41
42 WRITE_ONCE(success_audit, value);
43
44 return len;
45 }
46
47 /**
48 * getaudit() - Read handler for the securityfs node, "ipe/success_audit"
49 * @f: Supplies a file structure representing the securityfs node.
50 * @data: Supplies a buffer passed to the read syscall.
51 * @len: Supplies the length of @data.
52 * @offset: unused.
53 *
54 * Return: Length of buffer written
55 */
getaudit(struct file * f,char __user * data,size_t len,loff_t * offset)56 static ssize_t getaudit(struct file *f, char __user *data,
57 size_t len, loff_t *offset)
58 {
59 const char *result;
60
61 result = ((READ_ONCE(success_audit)) ? "1" : "0");
62
63 return simple_read_from_buffer(data, len, offset, result, 1);
64 }
65
66 /**
67 * setenforce() - Write handler for the securityfs node, "ipe/enforce"
68 * @f: Supplies a file structure representing the securityfs node.
69 * @data: Supplies a buffer passed to the write syscall.
70 * @len: Supplies the length of @data.
71 * @offset: unused.
72 *
73 * Return:
74 * * Length of buffer written - Success
75 * * %-EPERM - Insufficient permission
76 */
setenforce(struct file * f,const char __user * data,size_t len,loff_t * offset)77 static ssize_t setenforce(struct file *f, const char __user *data,
78 size_t len, loff_t *offset)
79 {
80 int rc = 0;
81 bool new_value, old_value;
82
83 if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
84 return -EPERM;
85
86 old_value = READ_ONCE(enforce);
87 rc = kstrtobool_from_user(data, len, &new_value);
88 if (rc)
89 return rc;
90
91 if (new_value != old_value) {
92 ipe_audit_enforce(new_value, old_value);
93 WRITE_ONCE(enforce, new_value);
94 }
95
96 return len;
97 }
98
99 /**
100 * getenforce() - Read handler for the securityfs node, "ipe/enforce"
101 * @f: Supplies a file structure representing the securityfs node.
102 * @data: Supplies a buffer passed to the read syscall.
103 * @len: Supplies the length of @data.
104 * @offset: unused.
105 *
106 * Return: Length of buffer written
107 */
getenforce(struct file * f,char __user * data,size_t len,loff_t * offset)108 static ssize_t getenforce(struct file *f, char __user *data,
109 size_t len, loff_t *offset)
110 {
111 const char *result;
112
113 result = ((READ_ONCE(enforce)) ? "1" : "0");
114
115 return simple_read_from_buffer(data, len, offset, result, 1);
116 }
117
118 /**
119 * new_policy() - Write handler for the securityfs node, "ipe/new_policy".
120 * @f: Supplies a file structure representing the securityfs node.
121 * @data: Supplies a buffer passed to the write syscall.
122 * @len: Supplies the length of @data.
123 * @offset: unused.
124 *
125 * Return:
126 * * Length of buffer written - Success
127 * * %-EPERM - Insufficient permission
128 * * %-ENOMEM - Out of memory (OOM)
129 * * %-EBADMSG - Policy is invalid
130 * * %-ERANGE - Policy version number overflow
131 * * %-EINVAL - Policy version parsing error
132 * * %-EEXIST - Same name policy already deployed
133 * * %-ENOKEY - Policy signing key not found
134 * * %-EKEYREJECTED - Policy signature verification failed
135 */
new_policy(struct file * f,const char __user * data,size_t len,loff_t * offset)136 static ssize_t new_policy(struct file *f, const char __user *data,
137 size_t len, loff_t *offset)
138 {
139 struct ipe_policy *p = NULL;
140 char *copy = NULL;
141 int rc = 0;
142
143 if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN)) {
144 rc = -EPERM;
145 goto out;
146 }
147
148 copy = memdup_user_nul(data, len);
149 if (IS_ERR(copy)) {
150 rc = PTR_ERR(copy);
151 copy = NULL;
152 goto out;
153 }
154
155 p = ipe_new_policy(NULL, 0, copy, len);
156 if (IS_ERR(p)) {
157 rc = PTR_ERR(p);
158 goto out;
159 }
160
161 rc = ipe_new_policyfs_node(p);
162
163 out:
164 kfree(copy);
165 if (rc < 0) {
166 ipe_free_policy(p);
167 ipe_audit_policy_load(ERR_PTR(rc));
168 return rc;
169 }
170
171 return len;
172 }
173
174 static const struct file_operations np_fops = {
175 .write = new_policy,
176 };
177
178 static const struct file_operations audit_fops = {
179 .write = setaudit,
180 .read = getaudit,
181 };
182
183 static const struct file_operations enforce_fops = {
184 .write = setenforce,
185 .read = getenforce,
186 };
187
188 /**
189 * ipe_init_securityfs() - Initialize IPE's securityfs tree at fsinit.
190 *
191 * Return: %0 on success. If an error occurs, the function will return
192 * the -errno.
193 */
ipe_init_securityfs(void)194 int __init ipe_init_securityfs(void)
195 {
196 int rc = 0;
197 struct ipe_policy *ap;
198 struct dentry *dentry;
199
200 if (!ipe_enabled)
201 return -EOPNOTSUPP;
202
203 root = securityfs_create_dir("ipe", NULL);
204 if (IS_ERR(root))
205 return PTR_ERR(root);
206
207 dentry = securityfs_create_file("success_audit", 0600, root,
208 NULL, &audit_fops);
209 if (IS_ERR(dentry)) {
210 rc = PTR_ERR(dentry);
211 goto err;
212 }
213
214 dentry = securityfs_create_file("enforce", 0600, root, NULL,
215 &enforce_fops);
216 if (IS_ERR(dentry)) {
217 rc = PTR_ERR(dentry);
218 goto err;
219 }
220
221 policy_root = securityfs_create_dir("policies", root);
222 if (IS_ERR(policy_root)) {
223 rc = PTR_ERR(policy_root);
224 goto err;
225 }
226
227 ap = rcu_access_pointer(ipe_active_policy);
228 if (ap) {
229 rc = ipe_new_policyfs_node(ap);
230 if (rc)
231 goto err;
232 }
233
234 dentry = securityfs_create_file("new_policy", 0200, root, NULL, &np_fops);
235 if (IS_ERR(dentry)) {
236 rc = PTR_ERR(dentry);
237 goto err;
238 }
239
240 return 0;
241 err:
242 securityfs_remove(root);
243 return rc;
244 }
245