by Thiébaud Weksteen

[permalink] [raw]

Subject: Re: [PATCH v3 4/5] efi: call get_event_log before ExitBootServices

On Mon, Mar 5, 2018 at 4:40 PM Marc-André Lureau
<[email protected]>
wrote:

> Hi Thiebaud

> On Wed, Sep 20, 2017 at 10:13 AM, Thiebaud Weksteen <[email protected]>
wrote:
> > With TPM 2.0 specification, the event logs may only be accessible by
> > calling an EFI Boot Service. Modify the EFI stub to copy the log area to
> > a new Linux-specific EFI configuration table so it remains accessible
> > once booted.
> >
> > When calling this service, it is possible to specify the expected format
> > of the logs: TPM 1.2 (SHA1) or TPM 2.0 ("Crypto Agile"). For now, only
the
> > first format is retrieved.
> >

> Do you have plans to add support for the crypto-agile format? I am
> working on uefi/ovmf support, and I am wondering if it is at all
> necessary to add support for the 1.2 format. What do you think? I can
> eventually try to work on 2.0 format support.

Yes, this is definitely my intent. I am running low on free time for this
piece of work to happen just now though.

Thanks

> Thanks

> > Signed-off-by: Thiebaud Weksteen <[email protected]>
> > ---
> > arch/x86/boot/compressed/eboot.c | 1 +
> > drivers/firmware/efi/Makefile | 2 +-
> > drivers/firmware/efi/efi.c | 4 ++
> > drivers/firmware/efi/libstub/Makefile | 3 +-
> > drivers/firmware/efi/libstub/tpm.c | 81
+++++++++++++++++++++++++++++++++++
> > drivers/firmware/efi/tpm.c | 40 +++++++++++++++++
> > include/linux/efi.h | 46 ++++++++++++++++++++
> > 7 files changed, 174 insertions(+), 3 deletions(-)
> > create mode 100644 drivers/firmware/efi/tpm.c
> >
> > diff --git a/arch/x86/boot/compressed/eboot.c
b/arch/x86/boot/compressed/eboot.c
> > index a1686f3dc295..ef6abe8b3788 100644
> > --- a/arch/x86/boot/compressed/eboot.c
> > +++ b/arch/x86/boot/compressed/eboot.c
> > @@ -999,6 +999,7 @@ struct boot_params *efi_main(struct efi_config *c,
> >
> > /* Ask the firmware to clear memory on unclean shutdown */
> > efi_enable_reset_attack_mitigation(sys_table);
> > + efi_retrieve_tpm2_eventlog(sys_table);
> >
> > setup_graphics(boot_params);
> >
> > diff --git a/drivers/firmware/efi/Makefile
b/drivers/firmware/efi/Makefile
> > index 0329d319d89a..2f074b5cde87 100644
> > --- a/drivers/firmware/efi/Makefile
> > +++ b/drivers/firmware/efi/Makefile
> > @@ -10,7 +10,7 @@
> > KASAN_SANITIZE_runtime-wrappers.o := n
> >
> > obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
> > -obj-$(CONFIG_EFI) += efi.o vars.o reboot.o
memattr.o
> > +obj-$(CONFIG_EFI) += efi.o vars.o reboot.o
memattr.o tpm.o
> > obj-$(CONFIG_EFI) += capsule.o memmap.o
> > obj-$(CONFIG_EFI_VARS) += efivars.o
> > obj-$(CONFIG_EFI_ESRT) += esrt.o
> > diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > index f97f272e16ee..0308acfaaf76 100644
> > --- a/drivers/firmware/efi/efi.c
> > +++ b/drivers/firmware/efi/efi.c
> > @@ -52,6 +52,7 @@ struct efi __read_mostly efi = {
> > .properties_table = EFI_INVALID_TABLE_ADDR,
> > .mem_attr_table = EFI_INVALID_TABLE_ADDR,
> > .rng_seed = EFI_INVALID_TABLE_ADDR,
> > + .tpm_log = EFI_INVALID_TABLE_ADDR
> > };
> > EXPORT_SYMBOL(efi);
> >
> > @@ -444,6 +445,7 @@ static __initdata efi_config_table_type_t
common_tables[] = {
> > {EFI_PROPERTIES_TABLE_GUID, "PROP", &efi.properties_table},
> > {EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR",
&efi.mem_attr_table},
> > {LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi.rng_seed},
> > + {LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
> > {NULL_GUID, NULL, NULL},
> > };
> >
> > @@ -532,6 +534,8 @@ int __init efi_config_parse_tables(void
*config_tables, int count, int sz,
> > if (efi_enabled(EFI_MEMMAP))
> > efi_memattr_init();
> >
> > + efi_tpm_eventlog_init();
> > +
> > /* Parse the EFI Properties table if it exists */
> > if (efi.properties_table != EFI_INVALID_TABLE_ADDR) {
> > efi_properties_table_t *tbl;
> > diff --git a/drivers/firmware/efi/libstub/Makefile
b/drivers/firmware/efi/libstub/Makefile
> > index dedf9bde44db..2abe6d22dc5f 100644
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -29,8 +29,7 @@ OBJECT_FILES_NON_STANDARD := y
> > # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
> > KCOV_INSTRUMENT := n
> >
> > -lib-y := efi-stub-helper.o gop.o secureboot.o
> > -lib-$(CONFIG_RESET_ATTACK_MITIGATION) += tpm.o
> > +lib-y := efi-stub-helper.o gop.o secureboot.o
tpm.o
> >
> > # include the stub's generic dependencies from lib/ when building for
ARM/arm64
> > arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c
fdt_sw.c sort.c
> > diff --git a/drivers/firmware/efi/libstub/tpm.c
b/drivers/firmware/efi/libstub/tpm.c
> > index 6224cdbc9669..da661bf8cb96 100644
> > --- a/drivers/firmware/efi/libstub/tpm.c
> > +++ b/drivers/firmware/efi/libstub/tpm.c
> > @@ -4,15 +4,18 @@
> > * Copyright (C) 2016 CoreOS, Inc
> > * Copyright (C) 2017 Google, Inc.
> > * Matthew Garrett <[email protected]>
> > + * Thiebaud Weksteen <[email protected]>
> > *
> > * This file is part of the Linux kernel, and is made available under
the
> > * terms of the GNU General Public License version 2.
> > */
> > #include <linux/efi.h>
> > +#include <linux/tpm_eventlog.h>
> > #include <asm/efi.h>
> >
> > #include "efistub.h"
> >
> > +#ifdef CONFIG_RESET_ATTACK_MITIGATION
> > static const efi_char16_t efi_MemoryOverWriteRequest_name[] = {
> > 'M', 'e', 'm', 'o', 'r', 'y', 'O', 'v', 'e', 'r', 'w', 'r',
'i', 't',
> > 'e', 'R', 'e', 'q', 'u', 'e', 's', 't', 'C', 'o', 'n', 't',
'r', 'o',
> > @@ -56,3 +59,81 @@ void
efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
> > EFI_VARIABLE_BOOTSERVICE_ACCESS |
> > EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);
> > }
> > +
> > +#endif
> > +
> > +void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> > +{
> > + efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
> > + efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
> > + efi_status_t status;
> > + efi_physical_addr_t log_location, log_last_entry;
> > + struct linux_efi_tpm_eventlog *log_tbl;
> > + unsigned long first_entry_addr, last_entry_addr;
> > + size_t log_size, last_entry_size;
> > + efi_bool_t truncated;
> > + void *tcg2_protocol;
> > +
> > + status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
> > + &tcg2_protocol);
> > + if (status != EFI_SUCCESS)
> > + return;
> > +
> > + status = efi_call_proto(efi_tcg2_protocol, get_event_log,
tcg2_protocol,
> > + EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
> > + &log_location, &log_last_entry,
&truncated);
> > + if (status != EFI_SUCCESS)
> > + return;
> > +
> > + if (!log_location)
> > + return;
> > + first_entry_addr = (unsigned long) log_location;
> > +
> > + /*
> > + * We populate the EFI table even if the logs are empty.
> > + */
> > + if (!log_last_entry) {
> > + log_size = 0;
> > + } else {
> > + last_entry_addr = (unsigned long) log_last_entry;
> > + /*
> > + * get_event_log only returns the address of the last
entry.
> > + * We need to calculate its size to deduce the full
size of
> > + * the logs.
> > + */
> > + last_entry_size = sizeof(struct tcpa_event) +
> > + ((struct tcpa_event *)
last_entry_addr)->event_size;
> > + log_size = log_last_entry - log_location +
last_entry_size;
> > + }
> > +
> > + /* Allocate space for the logs and copy them. */
> > + status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
> > + sizeof(*log_tbl) + log_size,
> > + (void **) &log_tbl);
> > +
> > + if (status != EFI_SUCCESS) {
> > + efi_printk(sys_table_arg,
> > + "Unable to allocate memory for event log\n");
> > + return;
> > + }
> > +
> > + memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
> > + log_tbl->size = log_size;
> > + log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> > + memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
> > +
> > + status = efi_call_early(install_configuration_table,
> > + &linux_eventlog_guid, log_tbl);
> > + if (status != EFI_SUCCESS)
> > + goto err_free;
> > + return;
> > +
> > +err_free:
> > + efi_call_early(free_pool, log_tbl);
> > +}
> > +
> > +void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
> > +{
> > + /* Only try to retrieve the logs in 1.2 format. */
> > + efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
> > +}
> > diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
> > new file mode 100644
> > index 000000000000..0cbeb3d46b18
> > --- /dev/null
> > +++ b/drivers/firmware/efi/tpm.c
> > @@ -0,0 +1,40 @@
> > +/*
> > + * Copyright (C) 2017 Google, Inc.
> > + * Thiebaud Weksteen <[email protected]>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#include <linux/efi.h>
> > +#include <linux/init.h>
> > +#include <linux/memblock.h>
> > +
> > +#include <asm/early_ioremap.h>
> > +
> > +/*
> > + * Reserve the memory associated with the TPM Event Log configuration
table.
> > + */
> > +int __init efi_tpm_eventlog_init(void)
> > +{
> > + struct linux_efi_tpm_eventlog *log_tbl;
> > + unsigned int tbl_size;
> > +
> > + if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
> > + return 0;
> > +
> > + log_tbl = early_memremap(efi.tpm_log, sizeof(*log_tbl));
> > + if (!log_tbl) {
> > + pr_err("Failed to map TPM Event Log table @ 0x%lx\n",
> > + efi.tpm_log);
> > + efi.tpm_log = EFI_INVALID_TABLE_ADDR;
> > + return -ENOMEM;
> > + }
> > +
> > + tbl_size = sizeof(*log_tbl) + log_tbl->size;
> > + memblock_reserve(efi.tpm_log, tbl_size);
> > + early_memunmap(log_tbl, sizeof(*log_tbl));
> > + return 0;
> > +}
> > +
> > diff --git a/include/linux/efi.h b/include/linux/efi.h
> > index 8dc3d94a3e3c..c5805eb601b1 100644
> > --- a/include/linux/efi.h
> > +++ b/include/linux/efi.h
> > @@ -472,6 +472,39 @@ typedef struct {
> > u64 get_all;
> > } apple_properties_protocol_64_t;
> >
> > +typedef struct {
> > + u32 get_capability;
> > + u32 get_event_log;
> > + u32 hash_log_extend_event;
> > + u32 submit_command;
> > + u32 get_active_pcr_banks;
> > + u32 set_active_pcr_banks;
> > + u32 get_result_of_set_active_pcr_banks;
> > +} efi_tcg2_protocol_32_t;
> > +
> > +typedef struct {
> > + u64 get_capability;
> > + u64 get_event_log;
> > + u64 hash_log_extend_event;
> > + u64 submit_command;
> > + u64 get_active_pcr_banks;
> > + u64 set_active_pcr_banks;
> > + u64 get_result_of_set_active_pcr_banks;
> > +} efi_tcg2_protocol_64_t;
> > +
> > +typedef u32 efi_tcg2_event_log_format;
> > +
> > +typedef struct {
> > + void *get_capability;
> > + efi_status_t (*get_event_log)(efi_handle_t,
efi_tcg2_event_log_format,
> > + efi_physical_addr_t *, efi_physical_addr_t *,
efi_bool_t *);
> > + void *hash_log_extend_event;
> > + void *submit_command;
> > + void *get_active_pcr_banks;
> > + void *set_active_pcr_banks;
> > + void *get_result_of_set_active_pcr_banks;
> > +} efi_tcg2_protocol_t;
> > +
> > /*
> > * Types and defines for EFI ResetSystem
> > */
> > @@ -622,6 +655,7 @@ void efi_native_runtime_setup(void);
> > #define EFI_MEMORY_ATTRIBUTES_TABLE_GUID EFI_GUID(0xdcfa911d,
0x26eb, 0x469f, 0xa2, 0x20, 0x38, 0xb7, 0xdc, 0x46, 0x12, 0x20)
> > #define EFI_CONSOLE_OUT_DEVICE_GUID EFI_GUID(0xd3b36f2c,
0xd551, 0x11d4, 0x9a, 0x46, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
> > #define APPLE_PROPERTIES_PROTOCOL_GUID EFI_GUID(0x91bd12fe,
0xf6c3, 0x44fb, 0xa5, 0xb7, 0x51, 0x22, 0xab, 0x30, 0x3a, 0xe0)
> > +#define EFI_TCG2_PROTOCOL_GUID EFI_GUID(0x607f766c,
0x7455, 0x42be, 0x93, 0x0b, 0xe4, 0xd7, 0x6d, 0xb2, 0x72, 0x0f)
> >
> > #define EFI_IMAGE_SECURITY_DATABASE_GUID EFI_GUID(0xd719b2cb,
0x3d3a, 0x4596, 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f)
> > #define EFI_SHIM_LOCK_GUID EFI_GUID(0x605dab50,
0xe046, 0x4300, 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23)
> > @@ -634,6 +668,7 @@ void efi_native_runtime_setup(void);
> > #define LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID EFI_GUID(0xe03fc20a,
0x85dc, 0x406e, 0xb9, 0x0e, 0x4a, 0xb5, 0x02, 0x37, 0x1d, 0x95)
> > #define LINUX_EFI_LOADER_ENTRY_GUID EFI_GUID(0x4a67b082,
0x0a4c, 0x41cf, 0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f)
> > #define LINUX_EFI_RANDOM_SEED_TABLE_GUID EFI_GUID(0x1ce1e5bc,
0x7ceb, 0x42f2, 0x81, 0xe5, 0x8a, 0xad, 0xf1, 0x80, 0xf5, 0x7b)
> > +#define LINUX_EFI_TPM_EVENT_LOG_GUID EFI_GUID(0xb7799cb0,
0xeca2, 0x4943, 0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa)
> >
> > typedef struct {
> > efi_guid_t guid;
> > @@ -908,6 +943,7 @@ extern struct efi {
> > unsigned long properties_table; /* properties table */
> > unsigned long mem_attr_table; /* memory attributes table */
> > unsigned long rng_seed; /* UEFI firmware random seed */
> > + unsigned long tpm_log; /* TPM2 Event Log table */
> > efi_get_time_t *get_time;
> > efi_set_time_t *set_time;
> > efi_get_wakeup_time_t *get_wakeup_time;
> > @@ -1504,6 +1540,8 @@ static inline void
> > efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
{ }
> > #endif
> >
> > +void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table);
> > +
> > /*
> > * Arch code can implement the following three template macros,
avoiding
> > * reptition for the void/non-void return cases of
{__,}efi_call_virt():
> > @@ -1571,4 +1609,12 @@ struct linux_efi_random_seed {
> > u8 bits[];
> > };
> >
> > +struct linux_efi_tpm_eventlog {
> > + u32 size;
> > + u8 version;
> > + u8 log[];
> > +};
> > +
> > +extern int efi_tpm_eventlog_init(void);
> > +
> > #endif /* _LINUX_EFI_H */
> > --
> > 2.14.1.821.g8fa685d3b7-goog
> >

> --
> Marc-André Lureau