summaryrefslogtreecommitdiffstats
path: root/src/boot/efi/secure-boot.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 20:49:52 +0000
commit55944e5e40b1be2afc4855d8d2baf4b73d1876b5 (patch)
tree33f869f55a1b149e9b7c2b7e201867ca5dd52992 /src/boot/efi/secure-boot.c
parentInitial commit. (diff)
downloadsystemd-55944e5e40b1be2afc4855d8d2baf4b73d1876b5.tar.xz
systemd-55944e5e40b1be2afc4855d8d2baf4b73d1876b5.zip
Adding upstream version 255.4.upstream/255.4
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/boot/efi/secure-boot.c')
-rw-r--r--src/boot/efi/secure-boot.c223
1 files changed, 223 insertions, 0 deletions
diff --git a/src/boot/efi/secure-boot.c b/src/boot/efi/secure-boot.c
new file mode 100644
index 0000000..f76d2f4
--- /dev/null
+++ b/src/boot/efi/secure-boot.c
@@ -0,0 +1,223 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "console.h"
+#include "proto/security-arch.h"
+#include "secure-boot.h"
+#include "util.h"
+#include "vmm.h"
+
+bool secure_boot_enabled(void) {
+ bool secure = false; /* avoid false maybe-uninitialized warning */
+ EFI_STATUS err;
+
+ err = efivar_get_boolean_u8(MAKE_GUID_PTR(EFI_GLOBAL_VARIABLE), u"SecureBoot", &secure);
+
+ return err == EFI_SUCCESS && secure;
+}
+
+SecureBootMode secure_boot_mode(void) {
+ bool secure, audit = false, deployed = false, setup = false;
+ EFI_STATUS err;
+
+ err = efivar_get_boolean_u8(MAKE_GUID_PTR(EFI_GLOBAL_VARIABLE), u"SecureBoot", &secure);
+ if (err != EFI_SUCCESS)
+ return SECURE_BOOT_UNSUPPORTED;
+
+ /* We can assume false for all these if they are abscent (AuditMode and
+ * DeployedMode may not exist on older firmware). */
+ (void) efivar_get_boolean_u8(MAKE_GUID_PTR(EFI_GLOBAL_VARIABLE), u"AuditMode", &audit);
+ (void) efivar_get_boolean_u8(MAKE_GUID_PTR(EFI_GLOBAL_VARIABLE), u"DeployedMode", &deployed);
+ (void) efivar_get_boolean_u8(MAKE_GUID_PTR(EFI_GLOBAL_VARIABLE), u"SetupMode", &setup);
+
+ return decode_secure_boot_mode(secure, audit, deployed, setup);
+}
+
+EFI_STATUS secure_boot_enroll_at(EFI_FILE *root_dir, const char16_t *path, bool force) {
+ assert(root_dir);
+ assert(path);
+
+ EFI_STATUS err;
+
+ clear_screen(COLOR_NORMAL);
+
+ /* Enrolling secure boot keys is safe to do in virtualized environments as there is nothing
+ * we can brick there. */
+ bool is_safe = in_hypervisor();
+
+ if (!is_safe && !force)
+ return EFI_SUCCESS;
+
+ printf("Enrolling secure boot keys from directory: %ls\n", path);
+
+ if (!is_safe) {
+ printf("Warning: Enrolling custom Secure Boot keys might soft-brick your machine!\n");
+
+ unsigned timeout_sec = 15;
+ for (;;) {
+ printf("\rEnrolling in %2u s, press any key to abort.", timeout_sec);
+
+ uint64_t key;
+ err = console_key_read(&key, 1000 * 1000);
+ if (err == EFI_NOT_READY)
+ continue;
+ if (err == EFI_TIMEOUT) {
+ if (timeout_sec == 0) /* continue enrolling keys */
+ break;
+ timeout_sec--;
+ continue;
+ }
+ if (err != EFI_SUCCESS)
+ return log_error_status(
+ err,
+ "Error waiting for user input to enroll Secure Boot keys: %m");
+
+ /* user aborted, returning EFI_SUCCESS here allows the user to go back to the menu */
+ return EFI_SUCCESS;
+ }
+
+ printf("\n");
+ }
+
+ _cleanup_(file_closep) EFI_FILE *dir = NULL;
+
+ err = open_directory(root_dir, path, &dir);
+ if (err != EFI_SUCCESS)
+ return log_error_status(err, "Failed opening keys directory %ls: %m", path);
+
+ struct {
+ const char16_t *name;
+ const char16_t *filename;
+ const EFI_GUID vendor;
+ char *buffer;
+ size_t size;
+ } sb_vars[] = {
+ { u"db", u"db.auth", EFI_IMAGE_SECURITY_DATABASE_GUID, NULL, 0 },
+ { u"KEK", u"KEK.auth", EFI_GLOBAL_VARIABLE, NULL, 0 },
+ { u"PK", u"PK.auth", EFI_GLOBAL_VARIABLE, NULL, 0 },
+ };
+
+ /* Make sure all keys files exist before we start enrolling them by loading them from the disk first. */
+ for (size_t i = 0; i < ELEMENTSOF(sb_vars); i++) {
+ err = file_read(dir, sb_vars[i].filename, 0, 0, &sb_vars[i].buffer, &sb_vars[i].size);
+ if (err != EFI_SUCCESS) {
+ log_error_status(err, "Failed reading file %ls\\%ls: %m", path, sb_vars[i].filename);
+ goto out_deallocate;
+ }
+ }
+
+ for (size_t i = 0; i < ELEMENTSOF(sb_vars); i++) {
+ uint32_t sb_vars_opts =
+ EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS |
+ EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS;
+
+ err = efivar_set_raw(&sb_vars[i].vendor, sb_vars[i].name, sb_vars[i].buffer, sb_vars[i].size, sb_vars_opts);
+ if (err != EFI_SUCCESS) {
+ log_error_status(err, "Failed to write %ls secure boot variable: %m", sb_vars[i].name);
+ goto out_deallocate;
+ }
+ }
+
+ printf("Custom Secure Boot keys successfully enrolled, rebooting the system now!\n");
+ /* The system should be in secure boot mode now and we could continue a regular boot. But at least
+ * TPM PCR7 measurements should change on next boot. Reboot now so that any OS we load does not end
+ * up relying on the old PCR state. */
+ RT->ResetSystem(EfiResetCold, EFI_SUCCESS, 0, NULL);
+ assert_not_reached();
+
+out_deallocate:
+ for (size_t i = 0; i < ELEMENTSOF(sb_vars); i++)
+ free(sb_vars[i].buffer);
+
+ return err;
+}
+
+static struct SecurityOverride {
+ EFI_SECURITY_ARCH_PROTOCOL *security;
+ EFI_SECURITY2_ARCH_PROTOCOL *security2;
+ EFI_SECURITY_FILE_AUTHENTICATION_STATE original_hook;
+ EFI_SECURITY2_FILE_AUTHENTICATION original_hook2;
+
+ security_validator_t validator;
+ const void *validator_ctx;
+} security_override;
+
+static EFIAPI EFI_STATUS security_hook(
+ const EFI_SECURITY_ARCH_PROTOCOL *this,
+ uint32_t authentication_status,
+ const EFI_DEVICE_PATH *file) {
+
+ assert(security_override.validator);
+ assert(security_override.security);
+ assert(security_override.original_hook);
+
+ if (security_override.validator(security_override.validator_ctx, file, NULL, 0))
+ return EFI_SUCCESS;
+
+ return security_override.original_hook(security_override.security, authentication_status, file);
+}
+
+static EFIAPI EFI_STATUS security2_hook(
+ const EFI_SECURITY2_ARCH_PROTOCOL *this,
+ const EFI_DEVICE_PATH *device_path,
+ void *file_buffer,
+ size_t file_size,
+ bool boot_policy) {
+
+ assert(security_override.validator);
+ assert(security_override.security2);
+ assert(security_override.original_hook2);
+
+ if (security_override.validator(security_override.validator_ctx, device_path, file_buffer, file_size))
+ return EFI_SUCCESS;
+
+ return security_override.original_hook2(
+ security_override.security2, device_path, file_buffer, file_size, boot_policy);
+}
+
+/* This replaces the platform provided security arch protocols hooks (defined in the UEFI Platform
+ * Initialization Specification) with our own that uses the given validator to decide if a image is to be
+ * trusted. If not running in secure boot or the protocols are not available nothing happens. The override
+ * must be removed with uninstall_security_override() after LoadImage() has been called.
+ *
+ * This is a hack as we do not own the security protocol instances and modifying them is not an official part
+ * of their spec. But there is little else we can do to circumvent secure boot short of implementing our own
+ * PE loader. We could replace the firmware instances with our own instance using
+ * ReinstallProtocolInterface(), but some firmware will still use the old ones. */
+void install_security_override(security_validator_t validator, const void *validator_ctx) {
+ EFI_STATUS err;
+
+ assert(validator);
+
+ if (!secure_boot_enabled())
+ return;
+
+ security_override = (struct SecurityOverride) {
+ .validator = validator,
+ .validator_ctx = validator_ctx,
+ };
+
+ EFI_SECURITY_ARCH_PROTOCOL *security = NULL;
+ err = BS->LocateProtocol(MAKE_GUID_PTR(EFI_SECURITY_ARCH_PROTOCOL), NULL, (void **) &security);
+ if (err == EFI_SUCCESS) {
+ security_override.security = security;
+ security_override.original_hook = security->FileAuthenticationState;
+ security->FileAuthenticationState = security_hook;
+ }
+
+ EFI_SECURITY2_ARCH_PROTOCOL *security2 = NULL;
+ err = BS->LocateProtocol(MAKE_GUID_PTR(EFI_SECURITY2_ARCH_PROTOCOL), NULL, (void **) &security2);
+ if (err == EFI_SUCCESS) {
+ security_override.security2 = security2;
+ security_override.original_hook2 = security2->FileAuthentication;
+ security2->FileAuthentication = security2_hook;
+ }
+}
+
+void uninstall_security_override(void) {
+ if (security_override.original_hook)
+ security_override.security->FileAuthenticationState = security_override.original_hook;
+ if (security_override.original_hook2)
+ security_override.security2->FileAuthentication = security_override.original_hook2;
+}