sd-boot: put hashed kernel command line in a PCR of the TPM

The UEFI BIOS already hashes the contents of the loaded image, so the
initrd and the command line of the binary are recorded.

Because manually added LoadOptions are not taken into account, these
should be recorded also.

This patch logs and extends a TPM PCR register with the LoadOptions.

This feature can be enabled with configure --enable-tpm

The PCR register index can be specified with
configure --with-tpm-pcrindex=<NUM>

6 files changed, 386 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index 125319fe48..3fd204c3bb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2701,6 +2701,7 @@ systemd_boot_headers = \
 	src/boot/efi/console.h \
 	src/boot/efi/graphics.h \
 	src/boot/efi/pefile.h \
+	src/boot/efi/measure.h \
 	src/boot/efi/disk.h
 
 systemd_boot_sources = \
@@ -2709,6 +2710,7 @@ systemd_boot_sources = \
 	src/boot/efi/graphics.c \
 	src/boot/efi/pefile.c \
 	src/boot/efi/disk.c \
+	src/boot/efi/measure.c \
 	src/boot/efi/boot.c
 
 EXTRA_DIST += $(systemd_boot_sources) $(systemd_boot_headers)
@@ -2745,6 +2747,7 @@ stub_headers = \
 	src/boot/efi/disk.h \
 	src/boot/efi/graphics.h \
 	src/boot/efi/splash.h \
+	src/boot/efi/measure.h \
 	src/boot/efi/linux.h
 
 stub_sources = \
@@ -2754,6 +2757,7 @@ stub_sources = \
 	src/boot/efi/graphics.c \
 	src/boot/efi/splash.c \
 	src/boot/efi/linux.c \
+	src/boot/efi/measure.c \
 	src/boot/efi/stub.c
 
 EXTRA_DIST += \
diff --git a/configure.ac b/configure.ac
index d05d0ba31f..7a9ecb02da 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1218,6 +1218,28 @@ AS_IF([test "x$enable_gnuefi" != "xno"], [
 AM_CONDITIONAL(HAVE_GNUEFI, [test "x$have_gnuefi" = xyes])
 
 # ------------------------------------------------------------------------------
+have_tpm=no
+AC_ARG_ENABLE([tpm], AS_HELP_STRING([--enable-tpm],[Enable optional TPM support]),
+                [case "${enableval}" in
+                        yes) have_tpm=yes ;;
+                        no) have_tpm=no ;;
+                        *) AC_MSG_ERROR(bad value ${enableval} for --enable-tpm) ;;
+                esac],
+                [have_tpm=no])
+
+if test "x${have_tpm}" != xno ; then
+        AC_DEFINE(SD_BOOT_LOG_TPM, 1, [Define if TPM should be used to log events and extend the registers])
+fi
+
+AC_ARG_WITH(tpm-pcrindex,
+        AS_HELP_STRING([--with-tpm-pcrindex=<NUM>],
+                [TPM PCR register number to use]),
+        [SD_TPM_PCR="$withval"],
+        [SD_TPM_PCR="8"])
+
+AC_DEFINE_UNQUOTED(SD_TPM_PCR, [$SD_TPM_PCR], [TPM PCR register number to use])
+
+# ------------------------------------------------------------------------------
 have_kdbus=no
 AC_ARG_ENABLE(kdbus, AS_HELP_STRING([--disable-kdbus], [do not connect to kdbus by default]))
 if test "x$enable_kdbus" != "xno"; then
@@ -1571,6 +1593,7 @@ AC_MSG_RESULT([
         dbus:                    ${have_dbus}
         nss-myhostname:          ${have_myhostname}
         hwdb:                    ${enable_hwdb}
+        tpm:                     ${have_tpm}
         kdbus:                   ${have_kdbus}
         Python:                  ${have_python}
         man pages:               ${have_manpages}
diff --git a/src/boot/efi/boot.c b/src/boot/efi/boot.c
index 893980071f..30c1ead1aa 100644
--- a/src/boot/efi/boot.c
+++ b/src/boot/efi/boot.c
@@ -22,6 +22,7 @@
 #include "linux.h"
 #include "pefile.h"
 #include "util.h"
+#include "measure.h"
 
 #ifndef EFI_OS_INDICATIONS_BOOT_TO_FW_UI
 #define EFI_OS_INDICATIONS_BOOT_TO_FW_UI 0x0000000000000001ULL
@@ -1644,6 +1645,18 @@ static EFI_STATUS image_start(EFI_HANDLE parent_image, const Config *config, con
                 }
                 loaded_image->LoadOptions = options;
                 loaded_image->LoadOptionsSize = (StrLen(loaded_image->LoadOptions)+1) * sizeof(CHAR16);
+
+#ifdef SD_BOOT_LOG_TPM
+                /* Try to log any options to the TPM, escpecially to catch manually edited options */
+                err = tpm_log_event(SD_TPM_PCR,
+                                    (EFI_PHYSICAL_ADDRESS) loaded_image->LoadOptions,
+                                    loaded_image->LoadOptionsSize, loaded_image->LoadOptions);
+                if (EFI_ERROR(err)) {
+                        Print(L"Unable to add image options measurement: %r", err);
+                        uefi_call_wrapper(BS->Stall, 1, 3 * 1000 * 1000);
+                        return err;
+                }
+#endif
         }
 
         efivar_set_time_usec(L"LoaderTimeExecUSec", 0);
diff --git a/src/boot/efi/measure.c b/src/boot/efi/measure.c
new file mode 100644
index 0000000000..7c016387c1
--- /dev/null
+++ b/src/boot/efi/measure.c
@@ -0,0 +1,312 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ */
+
+#ifdef SD_BOOT_LOG_TPM
+
+#include <efi.h>
+#include <efilib.h>
+#include "measure.h"
+
+#define EFI_TCG_PROTOCOL_GUID { 0xf541796d, 0xa62e, 0x4954, {0xa7, 0x75, 0x95, 0x84, 0xf6, 0x1b, 0x9c, 0xdd} }
+
+typedef struct _TCG_VERSION {
+        UINT8 Major;
+        UINT8 Minor;
+        UINT8 RevMajor;
+        UINT8 RevMinor;
+} TCG_VERSION;
+
+typedef struct _TCG_BOOT_SERVICE_CAPABILITY {
+        UINT8 Size;
+        struct _TCG_VERSION StructureVersion;
+        struct _TCG_VERSION ProtocolSpecVersion;
+        UINT8 HashAlgorithmBitmap;
+        BOOLEAN TPMPresentFlag;
+        BOOLEAN TPMDeactivatedFlag;
+} TCG_BOOT_SERVICE_CAPABILITY;
+
+typedef UINT32 TCG_ALGORITHM_ID;
+#define TCG_ALG_SHA 0x00000004  // The SHA1 algorithm
+
+#define SHA1_DIGEST_SIZE 20
+
+typedef struct _TCG_DIGEST {
+        UINT8 Digest[SHA1_DIGEST_SIZE];
+} TCG_DIGEST;
+
+#define EV_IPL 13
+
+typedef struct _TCG_PCR_EVENT {
+        UINT32 PCRIndex;
+        UINT32 EventType;
+        struct _TCG_DIGEST digest;
+        UINT32 EventSize;
+        UINT8 Event[1];
+} TCG_PCR_EVENT;
+
+INTERFACE_DECL(_EFI_TCG);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG_STATUS_CHECK) (IN struct _EFI_TCG * This,
+                                                   OUT struct _TCG_BOOT_SERVICE_CAPABILITY * ProtocolCapability,
+                                                   OUT UINT32 * TCGFeatureFlags,
+                                                   OUT EFI_PHYSICAL_ADDRESS * EventLogLocation,
+                                                   OUT EFI_PHYSICAL_ADDRESS * EventLogLastEntry);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG_HASH_ALL) (IN struct _EFI_TCG * This,
+                                               IN UINT8 * HashData,
+                                               IN UINT64 HashDataLen,
+                                               IN TCG_ALGORITHM_ID AlgorithmId,
+                                               IN OUT UINT64 * HashedDataLen, IN OUT UINT8 ** HashedDataResult);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG_LOG_EVENT) (IN struct _EFI_TCG * This,
+                                                IN struct _TCG_PCR_EVENT * TCGLogData,
+                                                IN OUT UINT32 * EventNumber, IN UINT32 Flags);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG_PASS_THROUGH_TO_TPM) (IN struct _EFI_TCG * This,
+                                                          IN UINT32 TpmInputParameterBlockSize,
+                                                          IN UINT8 * TpmInputParameterBlock,
+                                                          IN UINT32 TpmOutputParameterBlockSize,
+                                                          IN UINT8 * TpmOutputParameterBlock);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG_HASH_LOG_EXTEND_EVENT) (IN struct _EFI_TCG * This,
+                                                            IN EFI_PHYSICAL_ADDRESS HashData,
+                                                            IN UINT64 HashDataLen,
+                                                            IN TCG_ALGORITHM_ID AlgorithmId,
+                                                            IN struct _TCG_PCR_EVENT * TCGLogData,
+                                                            IN OUT UINT32 * EventNumber,
+                                                            OUT EFI_PHYSICAL_ADDRESS * EventLogLastEntry);
+
+typedef struct _EFI_TCG {
+        EFI_TCG_STATUS_CHECK StatusCheck;
+        EFI_TCG_HASH_ALL HashAll;
+        EFI_TCG_LOG_EVENT LogEvent;
+        EFI_TCG_PASS_THROUGH_TO_TPM PassThroughToTPM;
+        EFI_TCG_HASH_LOG_EXTEND_EVENT HashLogExtendEvent;
+} EFI_TCG;
+
+#define EFI_TCG2_PROTOCOL_GUID {0x607f766c, 0x7455, 0x42be, { 0x93, 0x0b, 0xe4, 0xd7, 0x6d, 0xb2, 0x72, 0x0f }}
+
+typedef struct tdEFI_TCG2_PROTOCOL EFI_TCG2_PROTOCOL;
+
+typedef struct tdEFI_TCG2_VERSION {
+        UINT8 Major;
+        UINT8 Minor;
+} EFI_TCG2_VERSION;
+
+typedef UINT32 EFI_TCG2_EVENT_LOG_BITMAP;
+typedef UINT32 EFI_TCG2_EVENT_LOG_FORMAT;
+typedef UINT32 EFI_TCG2_EVENT_ALGORITHM_BITMAP;
+
+#define EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2       0x00000001
+#define EFI_TCG2_EVENT_LOG_FORMAT_TCG_2         0x00000002
+
+typedef struct tdEFI_TCG2_BOOT_SERVICE_CAPABILITY {
+        UINT8 Size;
+        EFI_TCG2_VERSION StructureVersion;
+        EFI_TCG2_VERSION ProtocolVersion;
+        EFI_TCG2_EVENT_ALGORITHM_BITMAP HashAlgorithmBitmap;
+        EFI_TCG2_EVENT_LOG_BITMAP SupportedEventLogs;
+        BOOLEAN TPMPresentFlag;
+        UINT16 MaxCommandSize;
+        UINT16 MaxResponseSize;
+        UINT32 ManufacturerID;
+        UINT32 NumberOfPCRBanks;
+        EFI_TCG2_EVENT_ALGORITHM_BITMAP ActivePcrBanks;
+} EFI_TCG2_BOOT_SERVICE_CAPABILITY;
+
+#define EFI_TCG2_EVENT_HEADER_VERSION  1
+
+typedef struct {
+        UINT32 HeaderSize;
+        UINT16 HeaderVersion;
+        UINT32 PCRIndex;
+        UINT32 EventType;
+} EFI_TCG2_EVENT_HEADER;
+
+typedef struct tdEFI_TCG2_EVENT {
+        UINT32 Size;
+        EFI_TCG2_EVENT_HEADER Header;
+        UINT8 Event[1];
+} EFI_TCG2_EVENT;
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_GET_CAPABILITY) (IN EFI_TCG2_PROTOCOL * This,
+                                                      IN OUT EFI_TCG2_BOOT_SERVICE_CAPABILITY * ProtocolCapability);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_GET_EVENT_LOG) (IN EFI_TCG2_PROTOCOL * This,
+                                                     IN EFI_TCG2_EVENT_LOG_FORMAT EventLogFormat,
+                                                     OUT EFI_PHYSICAL_ADDRESS * EventLogLocation,
+                                                     OUT EFI_PHYSICAL_ADDRESS * EventLogLastEntry,
+                                                     OUT BOOLEAN * EventLogTruncated);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_HASH_LOG_EXTEND_EVENT) (IN EFI_TCG2_PROTOCOL * This,
+                                                             IN UINT64 Flags,
+                                                             IN EFI_PHYSICAL_ADDRESS DataToHash,
+                                                             IN UINT64 DataToHashLen, IN EFI_TCG2_EVENT * EfiTcgEvent);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_SUBMIT_COMMAND) (IN EFI_TCG2_PROTOCOL * This,
+                                                      IN UINT32 InputParameterBlockSize,
+                                                      IN UINT8 * InputParameterBlock,
+                                                      IN UINT32 OutputParameterBlockSize, IN UINT8 * OutputParameterBlock);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_GET_ACTIVE_PCR_BANKS) (IN EFI_TCG2_PROTOCOL * This, OUT UINT32 * ActivePcrBanks);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_SET_ACTIVE_PCR_BANKS) (IN EFI_TCG2_PROTOCOL * This, IN UINT32 ActivePcrBanks);
+
+typedef EFI_STATUS(EFIAPI * EFI_TCG2_GET_RESULT_OF_SET_ACTIVE_PCR_BANKS) (IN EFI_TCG2_PROTOCOL * This,
+                                                                          OUT UINT32 * OperationPresent, OUT UINT32 * Response);
+
+typedef struct tdEFI_TCG2_PROTOCOL {
+        EFI_TCG2_GET_CAPABILITY GetCapability;
+        EFI_TCG2_GET_EVENT_LOG GetEventLog;
+        EFI_TCG2_HASH_LOG_EXTEND_EVENT HashLogExtendEvent;
+        EFI_TCG2_SUBMIT_COMMAND SubmitCommand;
+        EFI_TCG2_GET_ACTIVE_PCR_BANKS GetActivePcrBanks;
+        EFI_TCG2_SET_ACTIVE_PCR_BANKS SetActivePcrBanks;
+        EFI_TCG2_GET_RESULT_OF_SET_ACTIVE_PCR_BANKS GetResultOfSetActivePcrBanks;
+} EFI_TCG2;
+
+
+static EFI_STATUS tpm1_measure_to_pcr_and_event_log(const EFI_TCG *tcg, UINT32 pcrindex, const EFI_PHYSICAL_ADDRESS buffer,
+                                                    UINTN buffer_size, const CHAR16 *description) {
+        EFI_STATUS status;
+        TCG_PCR_EVENT *tcg_event;
+        UINT32 event_number;
+        EFI_PHYSICAL_ADDRESS event_log_last;
+        UINTN desc_len;
+
+        desc_len = (StrLen(description) + 1) * sizeof(CHAR16);
+
+        tcg_event = AllocateZeroPool(desc_len + sizeof(TCG_PCR_EVENT));
+
+        if (tcg_event == NULL)
+                return EFI_OUT_OF_RESOURCES;
+
+        tcg_event->EventSize = desc_len;
+        CopyMem((VOID *) & tcg_event->Event[0], (VOID *) description, desc_len);
+
+        tcg_event->PCRIndex = pcrindex;
+        tcg_event->EventType = EV_IPL;
+
+        event_number = 1;
+        status = uefi_call_wrapper(tcg->HashLogExtendEvent, 7,
+                                   tcg, buffer, buffer_size, TCG_ALG_SHA, tcg_event, &event_number, &event_log_last);
+
+        if (EFI_ERROR(status))
+                return status;
+
+        uefi_call_wrapper(BS->FreePool, 1, tcg_event);
+
+        return EFI_SUCCESS;
+}
+
+
+static EFI_STATUS tpm2_measure_to_pcr_and_event_log(const EFI_TCG2 *tcg, UINT32 pcrindex, const EFI_PHYSICAL_ADDRESS buffer,
+                                                    UINT64 buffer_size, const CHAR16 *description) {
+        EFI_STATUS status;
+        EFI_TCG2_EVENT *tcg_event;
+        UINTN desc_len;
+
+        desc_len = StrLen(description) * sizeof(CHAR16);
+
+        tcg_event = AllocateZeroPool(sizeof(*tcg_event) - sizeof(tcg_event->Event) + desc_len + 1);
+
+        if (tcg_event == NULL)
+                return EFI_OUT_OF_RESOURCES;
+
+        tcg_event->Size = sizeof(EFI_TCG2_EVENT) - sizeof(tcg_event->Event) + desc_len + 1;
+        tcg_event->Header.HeaderSize = sizeof(EFI_TCG2_EVENT_HEADER);
+        tcg_event->Header.HeaderVersion = EFI_TCG2_EVENT_HEADER_VERSION;
+        tcg_event->Header.PCRIndex = pcrindex;
+        tcg_event->Header.EventType = EV_IPL;
+
+        CopyMem((VOID *) tcg_event->Event, (VOID *) description, desc_len);
+
+        status = uefi_call_wrapper(tcg->HashLogExtendEvent, 5, tcg, 0, buffer, buffer_size, tcg_event);
+
+        uefi_call_wrapper(BS->FreePool, 1, tcg_event);
+
+        if (EFI_ERROR(status))
+                return status;
+
+        return EFI_SUCCESS;
+}
+
+static EFI_TCG * tcg1_interface_check(void) {
+        EFI_GUID tpm_guid = EFI_TCG_PROTOCOL_GUID;
+        EFI_STATUS status;
+        EFI_TCG *tcg;
+        TCG_BOOT_SERVICE_CAPABILITY capability;
+        UINT32 features;
+        EFI_PHYSICAL_ADDRESS event_log_location;
+        EFI_PHYSICAL_ADDRESS event_log_last_entry;
+
+        status = LibLocateProtocol(&tpm_guid, (void **) &tcg);
+
+        if (EFI_ERROR(status))
+                return NULL;
+
+        capability.Size = (UINT8) sizeof(capability);
+        status = uefi_call_wrapper(tcg->StatusCheck, 5, tcg, &capability, &features, &event_log_location, &event_log_last_entry);
+
+        if (EFI_ERROR(status))
+                return NULL;
+
+        if (capability.TPMDeactivatedFlag)
+                return NULL;
+
+        if (!capability.TPMPresentFlag)
+                return NULL;
+
+        return tcg;
+}
+
+static EFI_TCG2 * tcg2_interface_check(void) {
+        EFI_GUID tpm2_guid = EFI_TCG2_PROTOCOL_GUID;
+        EFI_STATUS status;
+        EFI_TCG2 *tcg;
+        EFI_TCG2_BOOT_SERVICE_CAPABILITY capability;
+
+        status = LibLocateProtocol(&tpm2_guid, (void **) &tcg);
+
+        if (EFI_ERROR(status))
+                return NULL;
+
+        capability.Size = (UINT8) sizeof(capability);
+        status = uefi_call_wrapper(tcg->GetCapability, 2, tcg, &capability);
+
+        if (EFI_ERROR(status))
+                return NULL;
+
+        if (!capability.TPMPresentFlag)
+                return NULL;
+
+        return tcg;
+}
+
+EFI_STATUS tpm_log_event(UINT32 pcrindex, const EFI_PHYSICAL_ADDRESS buffer, UINTN buffer_size, const CHAR16 *description) {
+        EFI_TCG *tpm1;
+        EFI_TCG2 *tpm2;
+
+        tpm2 = tcg2_interface_check();
+        if (tpm2)
+                return tpm2_measure_to_pcr_and_event_log(tpm2, pcrindex, buffer, buffer_size, description);
+
+        tpm1 = tcg1_interface_check();
+        if (tpm1)
+                return tpm1_measure_to_pcr_and_event_log(tpm1, pcrindex, buffer, buffer_size, description);
+
+        /* No active TPM found, so don't return an error */
+        return EFI_SUCCESS;
+}
+
+#endif
diff --git a/src/boot/efi/measure.h b/src/boot/efi/measure.h
new file mode 100644
index 0000000000..a2cfe817d0
--- /dev/null
+++ b/src/boot/efi/measure.h
@@ -0,0 +1,21 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ */
+#ifndef __SDBOOT_MEASURE_H
+#define __SDBOOT_MEASURE_H
+
+#ifndef SD_TPM_PCR
+#define SD_TPM_PCR 8
+#endif
+
+EFI_STATUS tpm_log_event(UINT32 pcrindex, const EFI_PHYSICAL_ADDRESS buffer, UINTN buffer_size, const CHAR16 *description);
+#endif
diff --git a/src/boot/efi/stub.c b/src/boot/efi/stub.c
index 9633bc1792..1e250f34f4 100644
--- a/src/boot/efi/stub.c
+++ b/src/boot/efi/stub.c
@@ -20,6 +20,7 @@
 #include "pefile.h"
 #include "splash.h"
 #include "util.h"
+#include "measure.h"
 
 /* magic string to find in the binary image */
 static const char __attribute__((used)) magic[] = "#### LoaderInfo: systemd-stub " VERSION " ####";
@@ -97,6 +98,18 @@ EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
                 for (i = 0; i < cmdline_len; i++)
                         line[i] = options[i];
                 cmdline = line;
+
+#ifdef SD_BOOT_LOG_TPM
+                /* Try to log any options to the TPM, escpecially manually edited options */
+                err = tpm_log_event(SD_TPM_PCR,
+                                    (EFI_PHYSICAL_ADDRESS) loaded_image->LoadOptions,
+                                    loaded_image->LoadOptionsSize, loaded_image->LoadOptions);
+                if (EFI_ERROR(err)) {
+                        Print(L"Unable to add image options measurement: %r", err);
+                        uefi_call_wrapper(BS->Stall, 1, 3 * 1000 * 1000);
+                        return err;
+                }
+#endif
         }
 
         /* export the device path this image is started from */