1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
From: Matthew Garrett <matthew.garrett@nebula.com>
Date: Fri, 9 Aug 2013 18:36:30 -0400
Subject: [PATCH] Add option to automatically enforce module signatures when in
Secure Boot mode
UEFI Secure Boot provides a mechanism for ensuring that the firmware will
only load signed bootloaders and kernels. Certain use cases may also
require that all kernel modules also be signed. Add a configuration option
that enforces this automatically when enabled.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
---
Documentation/x86/zero-page.txt | 2 ++
arch/x86/Kconfig | 10 ++++++++++
arch/x86/boot/compressed/eboot.c | 36 +++++++++++++++++++++++++++++++++++
arch/x86/include/uapi/asm/bootparam.h | 3 ++-
arch/x86/kernel/setup.c | 6 ++++++
include/linux/module.h | 6 ++++++
kernel/module.c | 7 +++++++
7 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt
index 199f453cb4de..ec38acf00b40 100644
--- a/Documentation/x86/zero-page.txt
+++ b/Documentation/x86/zero-page.txt
@@ -30,6 +30,8 @@ Offset Proto Name Meaning
1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below)
1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer
(below)
+1EB/001 ALL kbd_status Numlock is enabled
+1EC/001 ALL secure_boot Secure boot is enabled in the firmware
1EF/001 ALL sentinel Used to detect broken bootloaders
290/040 ALL edd_mbr_sig_buffer EDD MBR signatures
2D0/A00 ALL e820_map E820 memory map table
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 41a503c15862..7b8969db8398 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1611,6 +1611,16 @@ config EFI_MIXED
If unsure, say N.
+config EFI_SECURE_BOOT_SIG_ENFORCE
+ def_bool n
+ prompt "Force module signing when UEFI Secure Boot is enabled"
+ ---help---
+ UEFI Secure Boot provides a mechanism for ensuring that the
+ firmware will only load signed bootloaders and kernels. Certain
+ use cases may also require that all kernel modules also be signed.
+ Say Y here to automatically enable module signature enforcement
+ when a system boots with UEFI Secure Boot enabled.
+
config SECCOMP
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 1acf605a646d..6da2da7ac9c3 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -12,6 +12,7 @@
#include <asm/efi.h>
#include <asm/setup.h>
#include <asm/desc.h>
+#include <asm/bootparam_utils.h>
#undef memcpy /* Use memcpy from misc.c */
@@ -828,6 +829,37 @@ out:
return status;
}
+static int get_secure_boot(void)
+{
+ u8 sb, setup;
+ unsigned long datasize = sizeof(sb);
+ efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID;
+ efi_status_t status;
+
+ status = efi_early->call((unsigned long)sys_table->runtime->get_variable,
+ L"SecureBoot", &var_guid, NULL, &datasize, &sb);
+
+ if (status != EFI_SUCCESS)
+ return 0;
+
+ if (sb == 0)
+ return 0;
+
+
+ status = efi_early->call((unsigned long)sys_table->runtime->get_variable,
+ L"SetupMode", &var_guid, NULL, &datasize,
+ &setup);
+
+ if (status != EFI_SUCCESS)
+ return 0;
+
+ if (setup == 1)
+ return 0;
+
+ return 1;
+}
+
+
/*
* See if we have Graphics Output Protocol
*/
@@ -1407,6 +1439,10 @@ struct boot_params *efi_main(struct efi_config *c,
else
setup_boot_services32(efi_early);
+ sanitize_boot_params(boot_params);
+
+ boot_params->secure_boot = get_secure_boot();
+
setup_graphics(boot_params);
setup_efi_pci(boot_params);
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index 225b0988043a..90dbfb73e11f 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -133,7 +133,8 @@ struct boot_params {
__u8 eddbuf_entries; /* 0x1e9 */
__u8 edd_mbr_sig_buf_entries; /* 0x1ea */
__u8 kbd_status; /* 0x1eb */
- __u8 _pad5[3]; /* 0x1ec */
+ __u8 secure_boot; /* 0x1ec */
+ __u8 _pad5[2]; /* 0x1ed */
/*
* The sentinel is set to a nonzero value (0xff) in header.S.
*
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index ab08aa2276fb..f4eb99432db1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1150,6 +1150,12 @@ void __init setup_arch(char **cmdline_p)
io_delay_init();
+#ifdef CONFIG_EFI_SECURE_BOOT_SIG_ENFORCE
+ if (boot_params.secure_boot) {
+ enforce_signed_modules();
+ }
+#endif
+
/*
* Parse the ACPI tables for possible boot-time SMP configuration.
*/
diff --git a/include/linux/module.h b/include/linux/module.h
index 341a73ecea2e..cca08ac450e2 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -188,6 +188,12 @@ const struct exception_table_entry *search_exception_tables(unsigned long add);
struct notifier_block;
+#ifdef CONFIG_MODULE_SIG
+extern void enforce_signed_modules(void);
+#else
+static inline void enforce_signed_modules(void) {};
+#endif
+
#ifdef CONFIG_MODULES
extern int modules_disabled; /* for sysctl */
diff --git a/kernel/module.c b/kernel/module.c
index 6507ffcb5445..cace4bd04956 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3845,6 +3845,13 @@ void module_layout(struct module *mod,
EXPORT_SYMBOL(module_layout);
#endif
+#ifdef CONFIG_MODULE_SIG
+void enforce_signed_modules(void)
+{
+ sig_enforce = true;
+}
+#endif
+
bool secure_modules(void)
{
#ifdef CONFIG_MODULE_SIG
--
2.1.0
|
