From dc0bc065607e95dc5b2d13d5f3319364f3d8202d Mon Sep 17 00:00:00 2001 From: Robbie Harwood Date: Thu, 30 Mar 2023 12:47:20 +0000 Subject: [PATCH] Disable the tpm verifier if the TPM device is not present Signed-off-by: Robbie Harwood --- ...tpm-verifier-if-the-TPM-device-is-no.patch | 156 ++++++++++++++++++ grub.patches | 1 + grub2.spec | 5 +- 3 files changed, 161 insertions(+), 1 deletion(-) create mode 100644 0328-tpm-Disable-the-tpm-verifier-if-the-TPM-device-is-no.patch diff --git a/0328-tpm-Disable-the-tpm-verifier-if-the-TPM-device-is-no.patch b/0328-tpm-Disable-the-tpm-verifier-if-the-TPM-device-is-no.patch new file mode 100644 index 0000000..9c2522c --- /dev/null +++ b/0328-tpm-Disable-the-tpm-verifier-if-the-TPM-device-is-no.patch @@ -0,0 +1,156 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: Michael Chang +Date: Wed, 22 Mar 2023 12:25:43 +0800 +Subject: [PATCH] tpm: Disable the tpm verifier if the TPM device is not + present + +When the tpm module is loaded, the verifier reads entire file into +memory, measures it and uses verified content as a backing buffer for +file accesses. However, this process may result in high memory +utilization for file operations, sometimes causing a system to run out +of memory which may finally lead to boot failure. To address this issue, +among others, the commit 887f98f0d (mm: Allow dynamically requesting +additional memory regions) have optimized memory management by +dynamically allocating heap space to maximize memory usage and reduce +threat of memory exhaustion. But in some cases problems may still arise, +e.g., when large ISO images are mounted using loopback or when dealing +with embedded systems with limited memory resources. + +Unfortunately current implementation of the tpm module doesn't allow +elimination of the back buffer once it is loaded. Even if the TPM device +is not present or it has been explicitly disabled. This may unnecessary +allocate a lot memory. To solve this issue, a patch has been developed +to detect the TPM status at module load and skip verifier registration +if the device is missing or deactivated. This prevents allocation of +memory for the back buffer, avoiding wasting memory when no real measure +boot functionality is performed. Disabling the TPM device in the system +can reduce memory usage in the GRUB. It is useful in scenarios where +high memory utilization is a concern and measurements of loaded +artifacts are not necessary. + +Signed-off-by: Michael Chang +Signed-off-by: Stefan Berger +Reviewed-by: Daniel Kiper +(cherry picked from commit 30708dfe3bebd62a5487437554da8a24253f519f) +--- + grub-core/commands/efi/tpm.c | 37 +++++++++++++++++++++++++++++++++++ + grub-core/commands/ieee1275/ibmvtpm.c | 20 +++++++++---------- + grub-core/commands/tpm.c | 10 ++++++++++ + include/grub/tpm.h | 1 + + 4 files changed, 58 insertions(+), 10 deletions(-) + +diff --git a/grub-core/commands/efi/tpm.c b/grub-core/commands/efi/tpm.c +index ae09c1bf8b..e1f343fea3 100644 +--- a/grub-core/commands/efi/tpm.c ++++ b/grub-core/commands/efi/tpm.c +@@ -287,3 +287,40 @@ grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr, + else + return grub_tpm2_log_event (tpm_handle, buf, size, pcr, description); + } ++ ++int ++grub_tpm_present (void) ++{ ++ grub_efi_handle_t tpm_handle; ++ grub_efi_uint8_t protocol_version; ++ ++ if (!grub_tpm_handle_find (&tpm_handle, &protocol_version)) ++ return 0; ++ ++ if (protocol_version == 1) ++ { ++ grub_efi_tpm_protocol_t *tpm; ++ ++ tpm = grub_efi_open_protocol (tpm_handle, &tpm_guid, ++ GRUB_EFI_OPEN_PROTOCOL_GET_PROTOCOL); ++ if (!tpm) ++ { ++ grub_dprintf ("tpm", "Cannot open TPM protocol\n"); ++ return 0; ++ } ++ return grub_tpm1_present (tpm); ++ } ++ else ++ { ++ grub_efi_tpm2_protocol_t *tpm; ++ ++ tpm = grub_efi_open_protocol (tpm_handle, &tpm2_guid, ++ GRUB_EFI_OPEN_PROTOCOL_GET_PROTOCOL); ++ if (!tpm) ++ { ++ grub_dprintf ("tpm", "Cannot open TPM protocol\n"); ++ return 0; ++ } ++ return grub_tpm2_present (tpm); ++ } ++} +diff --git a/grub-core/commands/ieee1275/ibmvtpm.c b/grub-core/commands/ieee1275/ibmvtpm.c +index 239942d27e..a6fee5c516 100644 +--- a/grub-core/commands/ieee1275/ibmvtpm.c ++++ b/grub-core/commands/ieee1275/ibmvtpm.c +@@ -135,16 +135,6 @@ grub_err_t + grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr, + const char *description) + { +- /* +- * Call tpm_init() 'late' rather than from GRUB_MOD_INIT() so that device nodes +- * can be found. +- */ +- grub_err_t err = tpm_init (); +- +- /* Absence of a TPM isn't a failure. */ +- if (err != GRUB_ERR_NONE) +- return GRUB_ERR_NONE; +- + grub_dprintf ("tpm", "log_event, pcr = %d, size = 0x%" PRIxGRUB_SIZE ", %s\n", + pcr, size, description); + +@@ -153,3 +143,13 @@ grub_tpm_measure (unsigned char *buf, grub_size_t size, grub_uint8_t pcr, + + return GRUB_ERR_NONE; + } ++ ++int ++grub_tpm_present (void) ++{ ++ /* ++ * Call tpm_init() "late" rather than from GRUB_MOD_INIT() so that device nodes ++ * can be found. ++ */ ++ return tpm_init() == GRUB_ERR_NONE; ++} +diff --git a/grub-core/commands/tpm.c b/grub-core/commands/tpm.c +index e287d042e6..5839053d3d 100644 +--- a/grub-core/commands/tpm.c ++++ b/grub-core/commands/tpm.c +@@ -86,10 +86,20 @@ struct grub_file_verifier grub_tpm_verifier = { + + GRUB_MOD_INIT (tpm) + { ++ /* ++ * Even though this now calls ibmvtpm's grub_tpm_present() from GRUB_MOD_INIT(), ++ * it does seem to call it late enough in the initialization sequence so ++ * that whatever discovered "device nodes" before this GRUB_MOD_INIT() is ++ * called, enables the ibmvtpm driver to see the device nodes. ++ */ ++ if (!grub_tpm_present()) ++ return; + grub_verifier_register (&grub_tpm_verifier); + } + + GRUB_MOD_FINI (tpm) + { ++ if (!grub_tpm_present()) ++ return; + grub_verifier_unregister (&grub_tpm_verifier); + } +diff --git a/include/grub/tpm.h b/include/grub/tpm.h +index 5c285cbc52..c19fcbd0a6 100644 +--- a/include/grub/tpm.h ++++ b/include/grub/tpm.h +@@ -36,4 +36,5 @@ + + grub_err_t grub_tpm_measure (unsigned char *buf, grub_size_t size, + grub_uint8_t pcr, const char *description); ++int grub_tpm_present (void); + #endif diff --git a/grub.patches b/grub.patches index 0268a42..10c552f 100644 --- a/grub.patches +++ b/grub.patches @@ -325,3 +325,4 @@ Patch0324: 0324-blscfg-check-for-mounted-boot-in-emu.patch Patch0325: 0325-emu-linux-work-around-systemctl-kexec-returning.patch Patch0326: 0326-kern-ieee1275-init-Convert-plain-numbers-to-constant.patch Patch0327: 0327-kern-ieee1275-init-Extended-support-in-Vec5.patch +Patch0328: 0328-tpm-Disable-the-tpm-verifier-if-the-TPM-device-is-no.patch diff --git a/grub2.spec b/grub2.spec index e84d7f1..811756b 100644 --- a/grub2.spec +++ b/grub2.spec @@ -17,7 +17,7 @@ Name: grub2 Epoch: 1 Version: 2.06 -Release: 91%{?dist} +Release: 92%{?dist} Summary: Bootloader with support for Linux, Multiboot and more License: GPLv3+ URL: http://www.gnu.org/software/grub/ @@ -544,6 +544,9 @@ mv ${EFI_HOME}/grub.cfg.stb ${EFI_HOME}/grub.cfg %endif %changelog +* Thu Mar 30 2023 Robbie Harwood - 2.06-92 +- Disable the tpm verifier if the TPM device is not present + * Thu Mar 30 2023 Robbie Harwood - 2.06-91 - ppc64le: more cas vec5 shenanigans