On 11/09/2024 12:51, Ard Biesheuvel wrote: > On Wed, 11 Sept 2024 at 12:41, Usama Arif <usamaarif642@xxxxxxxxx> wrote: >> >> Looking at the TPM spec [1] >> >> If the ACPI TPM2 table contains the address and size of the Platform >> Firmware TCG log, firmware “pins” the memory associated with the >> Platform FirmwareTCG log, and reports this memory as “Reserved” memory >> via the INT 15h/E820 interface. >> >> It looks like the firmware should pass this as reserved in e820 memory >> map. However, it doesn't seem to. The firmware being tested on is: >> dmidecode -s bios-version >> edk2-20240214-2.el9 >> >> When this area is not reserved, it comes up as usable in >> /sys/firmware/memmap. This means that kexec, which uses that memmap >> to find usable memory regions, can select the region where efi.tpm_log >> is and overwrite it and relocate_kernel. >> >> Having a fix in firmware can be difficult to get through. As a secondary >> fix, this patch marks that region as reserved in e820_table_firmware if it >> is currently E820_TYPE_RAM so that kexec doesn't use it for kernel segments. >> >> [1] https://trustedcomputinggroup.org/wp-content/uploads/PC-ClientPlatform_Profile_for_TPM_2p0_Systems_v49_161114_public-review.pdf >> >> Signed-off-by: Usama Arif <usamaarif642@xxxxxxxxx> Forgot to add: Reported-by: Breno Leitao <leitao@xxxxxxxxxx> > > I would expect the EFI memory map to E820 conversion implemented in > the EFI stub to take care of this. > > If you are not booting via the EFI stub, the bootloader is performing > this conversion, and so it should be done there instead. > I will look into this and report back. Thanks > >> --- >> arch/x86/include/asm/e820/api.h | 2 ++ >> arch/x86/kernel/e820.c | 6 ++++++ >> arch/x86/platform/efi/efi.c | 9 +++++++++ >> drivers/firmware/efi/tpm.c | 2 +- >> include/linux/efi.h | 7 +++++++ >> 5 files changed, 25 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/api.h >> index 2e74a7f0e935..4e9aa24f03bd 100644 >> --- a/arch/x86/include/asm/e820/api.h >> +++ b/arch/x86/include/asm/e820/api.h >> @@ -16,6 +16,8 @@ extern bool e820__mapped_all(u64 start, u64 end, enum e820_type type); >> >> extern void e820__range_add (u64 start, u64 size, enum e820_type type); >> extern u64 e820__range_update(u64 start, u64 size, enum e820_type old_type, enum e820_type new_type); >> +extern u64 e820__range_update_firmware(u64 start, u64 size, enum e820_type old_type, >> + enum e820_type new_type); >> extern u64 e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type); >> extern u64 e820__range_update_table(struct e820_table *t, u64 start, u64 size, enum e820_type old_type, enum e820_type new_type); >> >> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c >> index 4893d30ce438..912400161623 100644 >> --- a/arch/x86/kernel/e820.c >> +++ b/arch/x86/kernel/e820.c >> @@ -538,6 +538,12 @@ u64 __init e820__range_update_table(struct e820_table *t, u64 start, u64 size, >> return __e820__range_update(t, start, size, old_type, new_type); >> } >> >> +u64 __init e820__range_update_firmware(u64 start, u64 size, enum e820_type old_type, >> + enum e820_type new_type) >> +{ >> + return __e820__range_update(e820_table_firmware, start, size, old_type, new_type); >> +} >> + >> /* Remove a range of memory from the E820 table: */ >> u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type) >> { >> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c >> index 88a96816de9a..aa95f77d7a30 100644 >> --- a/arch/x86/platform/efi/efi.c >> +++ b/arch/x86/platform/efi/efi.c >> @@ -171,6 +171,15 @@ static void __init do_add_efi_memmap(void) >> e820__update_table(e820_table); >> } >> >> +/* Reserve firmware area if it was marked as RAM */ >> +void arch_update_firmware_area(u64 addr, u64 size) >> +{ >> + if (e820__get_entry_type(addr, addr + size) == E820_TYPE_RAM) { >> + e820__range_update_firmware(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED); >> + e820__update_table(e820_table_firmware); >> + } >> +} >> + >> /* >> * Given add_efi_memmap defaults to 0 and there is no alternative >> * e820 mechanism for soft-reserved memory, import the full EFI memory >> diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c >> index e8d69bd548f3..8e6e7131d718 100644 >> --- a/drivers/firmware/efi/tpm.c >> +++ b/drivers/firmware/efi/tpm.c >> @@ -60,6 +60,7 @@ int __init efi_tpm_eventlog_init(void) >> } >> >> tbl_size = sizeof(*log_tbl) + log_tbl->size; >> + arch_update_firmware_area(efi.tpm_log, tbl_size); >> memblock_reserve(efi.tpm_log, tbl_size); >> >> if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) { >> @@ -107,4 +108,3 @@ int __init efi_tpm_eventlog_init(void) >> early_memunmap(log_tbl, sizeof(*log_tbl)); >> return ret; >> } >> - >> diff --git a/include/linux/efi.h b/include/linux/efi.h >> index 6bf3c4fe8511..9c239cdff771 100644 >> --- a/include/linux/efi.h >> +++ b/include/linux/efi.h >> @@ -1371,4 +1371,11 @@ extern struct blocking_notifier_head efivar_ops_nh; >> void efivars_generic_ops_register(void); >> void efivars_generic_ops_unregister(void); >> >> +#ifdef CONFIG_X86_64 >> +void __init arch_update_firmware_area(u64 addr, u64 size); >> +#else >> +static inline void __init arch_update_firmware_area(u64 addr, u64 size) >> +{ >> +} >> +#endif >> #endif /* _LINUX_EFI_H */ >> -- >> 2.43.5 >>
