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-rw-r--r--meta/recipes-bsp/grub/files/CVE-2022-28735.patch271
1 files changed, 271 insertions, 0 deletions
diff --git a/meta/recipes-bsp/grub/files/CVE-2022-28735.patch b/meta/recipes-bsp/grub/files/CVE-2022-28735.patch
new file mode 100644
index 0000000000..89b653a8da
--- /dev/null
+++ b/meta/recipes-bsp/grub/files/CVE-2022-28735.patch
@@ -0,0 +1,271 @@
1From 6fe755c5c07bb386fda58306bfd19e4a1c974c53 Mon Sep 17 00:00:00 2001
2From: Julian Andres Klode <julian.klode@canonical.com>
3Date: Thu, 2 Dec 2021 15:03:53 +0100
4Subject: kern/efi/sb: Reject non-kernel files in the shim_lock verifier
5
6Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=6fe755c5c07bb386fda58306bfd19e4a1c974c53]
7CVE: CVE-2022-28735
8Signed-off-by: Hitendra Prajapati <hprajapati@mvista.com>
9
10We must not allow other verifiers to pass things like the GRUB modules.
11Instead of maintaining a blocklist, maintain an allowlist of things
12that we do not care about.
13
14This allowlist really should be made reusable, and shared by the
15lockdown verifier, but this is the minimal patch addressing
16security concerns where the TPM verifier was able to mark modules
17as verified (or the OpenPGP verifier for that matter), when it
18should not do so on shim-powered secure boot systems.
19
20Fixes: CVE-2022-28735
21
22Signed-off-by: Julian Andres Klode <julian.klode@canonical.com>
23Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
24---
25 grub-core/kern/efi/sb.c | 221 ++++++++++++++++++++++++++++++++++++++++
26 include/grub/verify.h | 1 +
27 2 files changed, 222 insertions(+)
28 create mode 100644 grub-core/kern/efi/sb.c
29
30diff --git a/grub-core/kern/efi/sb.c b/grub-core/kern/efi/sb.c
31new file mode 100644
32index 0000000..89c4bb3
33--- /dev/null
34+++ b/grub-core/kern/efi/sb.c
35@@ -0,0 +1,221 @@
36+/*
37+ * GRUB -- GRand Unified Bootloader
38+ * Copyright (C) 2020 Free Software Foundation, Inc.
39+ *
40+ * GRUB is free software: you can redistribute it and/or modify
41+ * it under the terms of the GNU General Public License as published by
42+ * the Free Software Foundation, either version 3 of the License, or
43+ * (at your option) any later version.
44+ *
45+ * GRUB is distributed in the hope that it will be useful,
46+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
47+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
48+ * GNU General Public License for more details.
49+ *
50+ * You should have received a copy of the GNU General Public License
51+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
52+ *
53+ * UEFI Secure Boot related checkings.
54+ */
55+
56+#include <grub/efi/efi.h>
57+#include <grub/efi/pe32.h>
58+#include <grub/efi/sb.h>
59+#include <grub/env.h>
60+#include <grub/err.h>
61+#include <grub/file.h>
62+#include <grub/i386/linux.h>
63+#include <grub/kernel.h>
64+#include <grub/mm.h>
65+#include <grub/types.h>
66+#include <grub/verify.h>
67+
68+static grub_efi_guid_t shim_lock_guid = GRUB_EFI_SHIM_LOCK_GUID;
69+
70+/*
71+ * Determine whether we're in secure boot mode.
72+ *
73+ * Please keep the logic in sync with the Linux kernel,
74+ * drivers/firmware/efi/libstub/secureboot.c:efi_get_secureboot().
75+ */
76+grub_uint8_t
77+grub_efi_get_secureboot (void)
78+{
79+ static grub_efi_guid_t efi_variable_guid = GRUB_EFI_GLOBAL_VARIABLE_GUID;
80+ grub_efi_status_t status;
81+ grub_efi_uint32_t attr = 0;
82+ grub_size_t size = 0;
83+ grub_uint8_t *secboot = NULL;
84+ grub_uint8_t *setupmode = NULL;
85+ grub_uint8_t *moksbstate = NULL;
86+ grub_uint8_t secureboot = GRUB_EFI_SECUREBOOT_MODE_UNKNOWN;
87+ const char *secureboot_str = "UNKNOWN";
88+
89+ status = grub_efi_get_variable ("SecureBoot", &efi_variable_guid,
90+ &size, (void **) &secboot);
91+
92+ if (status == GRUB_EFI_NOT_FOUND)
93+ {
94+ secureboot = GRUB_EFI_SECUREBOOT_MODE_DISABLED;
95+ goto out;
96+ }
97+
98+ if (status != GRUB_EFI_SUCCESS)
99+ goto out;
100+
101+ status = grub_efi_get_variable ("SetupMode", &efi_variable_guid,
102+ &size, (void **) &setupmode);
103+
104+ if (status != GRUB_EFI_SUCCESS)
105+ goto out;
106+
107+ if ((*secboot == 0) || (*setupmode == 1))
108+ {
109+ secureboot = GRUB_EFI_SECUREBOOT_MODE_DISABLED;
110+ goto out;
111+ }
112+
113+ /*
114+ * See if a user has put the shim into insecure mode. If so, and if the
115+ * variable doesn't have the runtime attribute set, we might as well
116+ * honor that.
117+ */
118+ status = grub_efi_get_variable_with_attributes ("MokSBState", &shim_lock_guid,
119+ &size, (void **) &moksbstate, &attr);
120+
121+ /* If it fails, we don't care why. Default to secure. */
122+ if (status != GRUB_EFI_SUCCESS)
123+ {
124+ secureboot = GRUB_EFI_SECUREBOOT_MODE_ENABLED;
125+ goto out;
126+ }
127+
128+ if (!(attr & GRUB_EFI_VARIABLE_RUNTIME_ACCESS) && *moksbstate == 1)
129+ {
130+ secureboot = GRUB_EFI_SECUREBOOT_MODE_DISABLED;
131+ goto out;
132+ }
133+
134+ secureboot = GRUB_EFI_SECUREBOOT_MODE_ENABLED;
135+
136+ out:
137+ grub_free (moksbstate);
138+ grub_free (setupmode);
139+ grub_free (secboot);
140+
141+ if (secureboot == GRUB_EFI_SECUREBOOT_MODE_DISABLED)
142+ secureboot_str = "Disabled";
143+ else if (secureboot == GRUB_EFI_SECUREBOOT_MODE_ENABLED)
144+ secureboot_str = "Enabled";
145+
146+ grub_dprintf ("efi", "UEFI Secure Boot state: %s\n", secureboot_str);
147+
148+ return secureboot;
149+}
150+
151+static grub_err_t
152+shim_lock_verifier_init (grub_file_t io __attribute__ ((unused)),
153+ enum grub_file_type type,
154+ void **context __attribute__ ((unused)),
155+ enum grub_verify_flags *flags)
156+{
157+ *flags = GRUB_VERIFY_FLAGS_NONE;
158+
159+ switch (type & GRUB_FILE_TYPE_MASK)
160+ {
161+ /* Files we check. */
162+ case GRUB_FILE_TYPE_LINUX_KERNEL:
163+ case GRUB_FILE_TYPE_MULTIBOOT_KERNEL:
164+ case GRUB_FILE_TYPE_BSD_KERNEL:
165+ case GRUB_FILE_TYPE_XNU_KERNEL:
166+ case GRUB_FILE_TYPE_PLAN9_KERNEL:
167+ case GRUB_FILE_TYPE_EFI_CHAINLOADED_IMAGE:
168+ *flags = GRUB_VERIFY_FLAGS_SINGLE_CHUNK;
169+ return GRUB_ERR_NONE;
170+
171+ /* Files that do not affect secureboot state. */
172+ case GRUB_FILE_TYPE_NONE:
173+ case GRUB_FILE_TYPE_LOOPBACK:
174+ case GRUB_FILE_TYPE_LINUX_INITRD:
175+ case GRUB_FILE_TYPE_OPENBSD_RAMDISK:
176+ case GRUB_FILE_TYPE_XNU_RAMDISK:
177+ case GRUB_FILE_TYPE_SIGNATURE:
178+ case GRUB_FILE_TYPE_PUBLIC_KEY:
179+ case GRUB_FILE_TYPE_PUBLIC_KEY_TRUST:
180+ case GRUB_FILE_TYPE_PRINT_BLOCKLIST:
181+ case GRUB_FILE_TYPE_TESTLOAD:
182+ case GRUB_FILE_TYPE_GET_SIZE:
183+ case GRUB_FILE_TYPE_FONT:
184+ case GRUB_FILE_TYPE_ZFS_ENCRYPTION_KEY:
185+ case GRUB_FILE_TYPE_CAT:
186+ case GRUB_FILE_TYPE_HEXCAT:
187+ case GRUB_FILE_TYPE_CMP:
188+ case GRUB_FILE_TYPE_HASHLIST:
189+ case GRUB_FILE_TYPE_TO_HASH:
190+ case GRUB_FILE_TYPE_KEYBOARD_LAYOUT:
191+ case GRUB_FILE_TYPE_PIXMAP:
192+ case GRUB_FILE_TYPE_GRUB_MODULE_LIST:
193+ case GRUB_FILE_TYPE_CONFIG:
194+ case GRUB_FILE_TYPE_THEME:
195+ case GRUB_FILE_TYPE_GETTEXT_CATALOG:
196+ case GRUB_FILE_TYPE_FS_SEARCH:
197+ case GRUB_FILE_TYPE_LOADENV:
198+ case GRUB_FILE_TYPE_SAVEENV:
199+ case GRUB_FILE_TYPE_VERIFY_SIGNATURE:
200+ *flags = GRUB_VERIFY_FLAGS_SKIP_VERIFICATION;
201+ return GRUB_ERR_NONE;
202+
203+ /* Other files. */
204+ default:
205+ return grub_error (GRUB_ERR_ACCESS_DENIED, N_("prohibited by secure boot policy"));
206+ }
207+}
208+
209+static grub_err_t
210+shim_lock_verifier_write (void *context __attribute__ ((unused)), void *buf, grub_size_t size)
211+{
212+ grub_efi_shim_lock_protocol_t *sl = grub_efi_locate_protocol (&shim_lock_guid, 0);
213+
214+ if (!sl)
215+ return grub_error (GRUB_ERR_ACCESS_DENIED, N_("shim_lock protocol not found"));
216+
217+ if (sl->verify (buf, size) != GRUB_EFI_SUCCESS)
218+ return grub_error (GRUB_ERR_BAD_SIGNATURE, N_("bad shim signature"));
219+
220+ return GRUB_ERR_NONE;
221+}
222+
223+struct grub_file_verifier shim_lock_verifier =
224+ {
225+ .name = "shim_lock_verifier",
226+ .init = shim_lock_verifier_init,
227+ .write = shim_lock_verifier_write
228+ };
229+
230+void
231+grub_shim_lock_verifier_setup (void)
232+{
233+ struct grub_module_header *header;
234+ grub_efi_shim_lock_protocol_t *sl =
235+ grub_efi_locate_protocol (&shim_lock_guid, 0);
236+
237+ /* shim_lock is missing, check if GRUB image is built with --disable-shim-lock. */
238+ if (!sl)
239+ {
240+ FOR_MODULES (header)
241+ {
242+ if (header->type == OBJ_TYPE_DISABLE_SHIM_LOCK)
243+ return;
244+ }
245+ }
246+
247+ /* Secure Boot is off. Do not load shim_lock. */
248+ if (grub_efi_get_secureboot () != GRUB_EFI_SECUREBOOT_MODE_ENABLED)
249+ return;
250+
251+ /* Enforce shim_lock_verifier. */
252+ grub_verifier_register (&shim_lock_verifier);
253+
254+ grub_env_set ("shim_lock", "y");
255+ grub_env_export ("shim_lock");
256+}
257diff --git a/include/grub/verify.h b/include/grub/verify.h
258index cd129c3..672ae16 100644
259--- a/include/grub/verify.h
260+++ b/include/grub/verify.h
261@@ -24,6 +24,7 @@
262
263 enum grub_verify_flags
264 {
265+ GRUB_VERIFY_FLAGS_NONE = 0,
266 GRUB_VERIFY_FLAGS_SKIP_VERIFICATION = 1,
267 GRUB_VERIFY_FLAGS_SINGLE_CHUNK = 2,
268 /* Defer verification to another authority. */
269--
2702.25.1
271
generated by cgit v1.2.3-54-g00ecf (git 2.39.0) at 2024-05-17 18:56:31 +0000