1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2021 Google LLC
4 *
5 * This file can optionally be built into fips140.ko in order to support certain
6 * types of testing that the FIPS lab has to do to evaluate the module. It
7 * should not be included in production builds of the module.
8 */
9
10 /*
11 * We have to redefine inline to mean always_inline, so that _copy_to_user()
12 * gets inlined. This is needed for it to be placed into the correct section.
13 * See fips140_copy_to_user().
14 *
15 * We also need to undefine BUILD_FIPS140_KO to allow the use of the code
16 * patching which copy_to_user() requires.
17 */
18 #undef inline
19 #define inline inline __attribute__((__always_inline__)) __gnu_inline \
20 __inline_maybe_unused notrace
21 #undef BUILD_FIPS140_KO
22
23 /*
24 * Since this .c file contains real module parameters for fips140.ko, it needs
25 * to be compiled normally, so undo the hacks that were done in fips140-defs.h.
26 */
27 #define MODULE
28 #undef KBUILD_MODFILE
29 #undef __DISABLE_EXPORTS
30
31 #include <linux/cdev.h>
32 #include <linux/fs.h>
33 #include <linux/module.h>
34 #include <linux/slab.h>
35
36 #include "fips140-module.h"
37 #include "fips140-eval-testing-uapi.h"
38
39 /*
40 * This option allows deliberately failing the self-tests for a particular
41 * algorithm.
42 */
43 static char *fips140_fail_selftest;
44 module_param_named(fail_selftest, fips140_fail_selftest, charp, 0);
45
46 /* This option allows deliberately failing the integrity check. */
47 static bool fips140_fail_integrity_check;
48 module_param_named(fail_integrity_check, fips140_fail_integrity_check, bool, 0);
49
50 static dev_t fips140_devnum;
51 static struct cdev fips140_cdev;
52
53 /* Inject a self-test failure (via corrupting the result) if requested. */
fips140_inject_selftest_failure(const char * impl,u8 * result)54 void fips140_inject_selftest_failure(const char *impl, u8 *result)
55 {
56 if (fips140_fail_selftest && strcmp(impl, fips140_fail_selftest) == 0)
57 result[0] ^= 0xff;
58 }
59
60 /* Inject an integrity check failure (via corrupting the text) if requested. */
fips140_inject_integrity_failure(u8 * textcopy)61 void fips140_inject_integrity_failure(u8 *textcopy)
62 {
63 if (fips140_fail_integrity_check)
64 textcopy[0] ^= 0xff;
65 }
66
fips140_ioctl_is_approved_service(unsigned long arg)67 static long fips140_ioctl_is_approved_service(unsigned long arg)
68 {
69 const char *service_name = strndup_user((const char __user *)arg, 256);
70 long ret;
71
72 if (IS_ERR(service_name))
73 return PTR_ERR(service_name);
74
75 ret = fips140_is_approved_service(service_name);
76
77 kfree(service_name);
78 return ret;
79 }
80
81 /*
82 * Code in fips140.ko is covered by an integrity check by default, and this
83 * check breaks if copy_to_user() is called. This is because copy_to_user() is
84 * an inline function that relies on code patching. However, since this is
85 * "evaluation testing" code which isn't included in the production builds of
86 * fips140.ko, it's acceptable to just exclude it from the integrity check.
87 */
88 static noinline unsigned long __section("text.._fips140_unchecked")
fips140_copy_to_user(void __user * to,const void * from,unsigned long n)89 fips140_copy_to_user(void __user *to, const void *from, unsigned long n)
90 {
91 return copy_to_user(to, from, n);
92 }
93
fips140_ioctl_module_version(unsigned long arg)94 static long fips140_ioctl_module_version(unsigned long arg)
95 {
96 const char *version = fips140_module_version();
97 size_t len = strlen(version) + 1;
98
99 if (len > 256)
100 return -EOVERFLOW;
101
102 if (fips140_copy_to_user((void __user *)arg, version, len))
103 return -EFAULT;
104
105 return 0;
106 }
107
fips140_ioctl(struct file * file,unsigned int cmd,unsigned long arg)108 static long fips140_ioctl(struct file *file, unsigned int cmd,
109 unsigned long arg)
110 {
111 switch (cmd) {
112 case FIPS140_IOCTL_IS_APPROVED_SERVICE:
113 return fips140_ioctl_is_approved_service(arg);
114 case FIPS140_IOCTL_MODULE_VERSION:
115 return fips140_ioctl_module_version(arg);
116 default:
117 return -ENOTTY;
118 }
119 }
120
121 static const struct file_operations fips140_fops = {
122 .unlocked_ioctl = fips140_ioctl,
123 };
124
fips140_eval_testing_init(void)125 bool fips140_eval_testing_init(void)
126 {
127 if (alloc_chrdev_region(&fips140_devnum, 1, 1, "fips140") != 0) {
128 pr_err("failed to allocate device number\n");
129 return false;
130 }
131 cdev_init(&fips140_cdev, &fips140_fops);
132 if (cdev_add(&fips140_cdev, fips140_devnum, 1) != 0) {
133 pr_err("failed to add fips140 character device\n");
134 return false;
135 }
136 return true;
137 }
138