summaryrefslogtreecommitdiff
path: root/include/linux/tpm_eventlog.h
AgeCommit message (Collapse)AuthorFilesLines
2023-01-13efi: tpm: Avoid READ_ONCE() for accessing the event logArd Biesheuvel1-2/+2
Nathan reports that recent kernels built with LTO will crash when doing EFI boot using Fedora's GRUB and SHIM. The culprit turns out to be a misaligned load from the TPM event log, which is annotated with READ_ONCE(), and under LTO, this gets translated into a LDAR instruction which does not tolerate misaligned accesses. Interestingly, this does not happen when booting the same kernel straight from the UEFI shell, and so the fact that the event log may appear misaligned in memory may be caused by a bug in GRUB or SHIM. However, using READ_ONCE() to access firmware tables is slightly unusual in any case, and here, we only need to ensure that 'event' is not dereferenced again after it gets unmapped, but this is already taken care of by the implicit barrier() semantics of the early_memunmap() call. Cc: <stable@vger.kernel.org> Cc: Peter Jones <pjones@redhat.com> Cc: Jarkko Sakkinen <jarkko@kernel.org> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Reported-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://github.com/ClangBuiltLinux/linux/issues/1782 Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-08-03tpm: eventlog: Fix section mismatch for DEBUG_SECTION_MISMATCHHuacai Chen1-1/+1
If DEBUG_SECTION_MISMATCH enabled, __calc_tpm2_event_size() will not be inlined, this cause section mismatch like this: WARNING: modpost: vmlinux.o(.text.unlikely+0xe30c): Section mismatch in reference from the variable L0 to the function .init.text:early_ioremap() The function L0() references the function __init early_memremap(). This is often because L0 lacks a __init annotation or the annotation of early_ioremap is wrong. Fix it by using __always_inline instead of inline for the called-once function __calc_tpm2_event_size(). Fixes: 44038bc514a2 ("tpm: Abstract crypto agile event size calculations") Cc: stable@vger.kernel.org # v5.3 Reported-by: WANG Xuerui <git@xen0n.name> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
2020-07-24tpm: Require that all digests are present in TCG_PCR_EVENT2 structuresTyler Hicks1-2/+9
Require that the TCG_PCR_EVENT2.digests.count value strictly matches the value of TCG_EfiSpecIdEvent.numberOfAlgorithms in the event field of the TCG_PCClientPCREvent event log header. Also require that TCG_EfiSpecIdEvent.numberOfAlgorithms is non-zero. The TCG PC Client Platform Firmware Profile Specification section 9.1 (Family "2.0", Level 00 Revision 1.04) states: For each Hash algorithm enumerated in the TCG_PCClientPCREvent entry, there SHALL be a corresponding digest in all TCG_PCR_EVENT2 structures. Note: This includes EV_NO_ACTION events which do not extend the PCR. Section 9.4.5.1 provides this description of TCG_EfiSpecIdEvent.numberOfAlgorithms: The number of Hash algorithms in the digestSizes field. This field MUST be set to a value of 0x01 or greater. Enforce these restrictions, as required by the above specification, in order to better identify and ignore invalid sequences of bytes at the end of an otherwise valid TPM2 event log. Firmware doesn't always have the means necessary to inform the kernel of the actual event log size so the kernel's event log parsing code should be stringent when parsing the event log for resiliency against firmware bugs. This is true, for example, when firmware passes the event log to the kernel via a reserved memory region described in device tree. POWER and some ARM systems use the "linux,sml-base" and "linux,sml-size" device tree properties to describe the memory region used to pass the event log from firmware to the kernel. Unfortunately, the "linux,sml-size" property describes the size of the entire reserved memory region rather than the size of the event long within the memory region and the event log format does not include information describing the size of the event log. tpm_read_log_of(), in drivers/char/tpm/eventlog/of.c, is where the "linux,sml-size" property is used. At the end of that function, log->bios_event_log_end is pointing at the end of the reserved memory region. That's typically 0x10000 bytes offset from "linux,sml-base", depending on what's defined in the device tree source. The firmware event log only fills a portion of those 0x10000 bytes and the rest of the memory region should be zeroed out by firmware. Even in the case of a properly zeroed bytes in the remainder of the memory region, the only thing allowing the kernel's event log parser to detect the end of the event log is the following conditional in __calc_tpm2_event_size(): if (event_type == 0 && event_field->event_size == 0) size = 0; If that wasn't there, __calc_tpm2_event_size() would think that a 16 byte sequence of zeroes, following an otherwise valid event log, was a valid event. However, problems can occur if a single bit is set in the offset corresponding to either the TCG_PCR_EVENT2.eventType or TCG_PCR_EVENT2.eventSize fields, after the last valid event log entry. This could confuse the parser into thinking that an additional entry is present in the event log and exposing this invalid entry to userspace in the /sys/kernel/security/tpm0/binary_bios_measurements file. Such problems have been seen if firmware does not fully zero the memory region upon a warm reboot. This patch significantly raises the bar on how difficult it is for stale/invalid memory to confuse the kernel's event log parser but there's still, ultimately, a reliance on firmware to properly initialize the remainder of the memory region reserved for the event log as the parser cannot be expected to detect a stale but otherwise properly formatted firmware event log entry. Fixes: fd5c78694f3f ("tpm: fix handling of the TPM 2.0 event logs") Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2020-06-15efi/tpm: Verify event log header before parsingFabian Vogt1-1/+13
It is possible that the first event in the event log is not actually a log header at all, but rather a normal event. This leads to the cast in __calc_tpm2_event_size being an invalid conversion, which means that the values read are effectively garbage. Depending on the first event's contents, this leads either to apparently normal behaviour, a crash or a freeze. While this behaviour of the firmware is not in accordance with the TCG Client EFI Specification, this happens on a Dell Precision 5510 with the TPM enabled but hidden from the OS ("TPM On" disabled, state otherwise untouched). The EFI firmware claims that the TPM is present and active and that it supports the TCG 2.0 event log format. Fortunately, this can be worked around by simply checking the header of the first event and the event log header signature itself. Commit b4f1874c6216 ("tpm: check event log version before reading final events") addressed a similar issue also found on Dell models. Fixes: 6b0326190205 ("efi: Attempt to get the TCG2 event log in the boot stub") Signed-off-by: Fabian Vogt <fvogt@suse.de> Link: https://lore.kernel.org/r/1927248.evlx2EsYKh@linux-e202.suse.de Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1165773 Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-22tpm: eventlog: Replace zero-length array with flexible-array memberGustavo A. R. Silva1-1/+1
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. Also, the following issue shows up due to the flexible-array member having incomplete type[4]: drivers/char/tpm/eventlog/tpm2.c: In function ‘tpm2_bios_measurements_start’: drivers/char/tpm/eventlog/tpm2.c:54:46: error: invalid application of ‘sizeof’ to incomplete type ‘u8[]’ {aka ‘unsigned char[]’} 54 | size = sizeof(struct tcg_pcr_event) - sizeof(event_header->event) | ^ drivers/char/tpm/eventlog/tpm2.c: In function ‘tpm2_bios_measurements_next’: drivers/char/tpm/eventlog/tpm2.c:102:10: error: invalid application of ‘sizeof’ to incomplete type ‘u8[]’ {aka ‘unsigned char[]’} 102 | sizeof(event_header->event) + event_header->event_size; | ^ drivers/char/tpm/eventlog/tpm2.c: In function ‘tpm2_binary_bios_measurements_show’: drivers/char/tpm/eventlog/tpm2.c:140:10: error: invalid application of ‘sizeof’ to incomplete type ‘u8[]’ {aka ‘unsigned char[]’} 140 | sizeof(event_header->event) + event_header->event_size; | ^ scripts/Makefile.build:266: recipe for target 'drivers/char/tpm/eventlog/tpm2.o' failed make[3]: *** [drivers/char/tpm/eventlog/tpm2.o] Error 1 As mentioned above: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] As in "sizeof(event_header->event) always evaluated to 0, so removing it has no effect". Lastly, make use of the struct_size() helper to deal with the flexible array member and its host structure. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") [4] https://github.com/KSPP/linux/issues/43 Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2020-04-18tpm_eventlog.h: Replace zero-length array with flexible-array memberGustavo A. R. Silva1-3/+3
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2019-10-07efi/tpm: Only set 'efi_tpm_final_log_size' after successful event log parsingJerry Snitselaar1-1/+1
If __calc_tpm2_event_size() fails to parse an event it will return 0, resulting tpm2_calc_event_log_size() returning -1. Currently there is no check of this return value, and 'efi_tpm_final_log_size' can end up being set to this negative value resulting in a crash like this one: BUG: unable to handle page fault for address: ffffbc8fc00866ad #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page RIP: 0010:memcpy_erms+0x6/0x10 Call Trace: tpm_read_log_efi() tpm_bios_log_setup() tpm_chip_register() tpm_tis_core_init.cold.9+0x28c/0x466 tpm_tis_plat_probe() platform_drv_probe() ... Also __calc_tpm2_event_size() returns a size of 0 when it fails to parse an event, so update function documentation to reflect this. The root cause of the issue that caused the failure of event parsing in this case is resolved by Peter Jone's patchset dealing with large event logs where crossing over a page boundary causes the page with the event count to be unmapped. Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Ben Dooks <ben.dooks@codethink.co.uk> Cc: Dave Young <dyoung@redhat.com> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lukas Wunner <lukas@wunner.de> Cc: Lyude Paul <lyude@redhat.com> Cc: Matthew Garrett <mjg59@google.com> Cc: Octavian Purdila <octavian.purdila@intel.com> Cc: Peter Jones <pjones@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott Talbert <swt@techie.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Cc: linux-integrity@vger.kernel.org Cc: stable@vger.kernel.org Fixes: c46f3405692de ("tpm: Reserve the TPM final events table") Link: https://lkml.kernel.org/r/20191002165904.8819-6-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-07efi/tpm: Don't access event->count when it isn't mappedPeter Jones1-3/+11
Some machines generate a lot of event log entries. When we're iterating over them, the code removes the old mapping and adds a new one, so once we cross the page boundary we're unmapping the page with the count on it. Hilarity ensues. This patch keeps the info from the header in local variables so we don't need to access that page again or keep track of if it's mapped. Tested-by: Lyude Paul <lyude@redhat.com> Signed-off-by: Peter Jones <pjones@redhat.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Acked-by: Matthew Garrett <mjg59@google.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Ben Dooks <ben.dooks@codethink.co.uk> Cc: Dave Young <dyoung@redhat.com> Cc: Jerry Snitselaar <jsnitsel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lukas Wunner <lukas@wunner.de> Cc: Octavian Purdila <octavian.purdila@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott Talbert <swt@techie.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Cc: linux-integrity@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 44038bc514a2 ("tpm: Abstract crypto agile event size calculations") Link: https://lkml.kernel.org/r/20191002165904.8819-4-ard.biesheuvel@linaro.org [ Minor edits. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24tpm: Reserve the TPM final events tableMatthew Garrett1-9/+93
UEFI systems provide a boot services protocol for obtaining the TPM event log, but this is unusable after ExitBootServices() is called. Unfortunately ExitBootServices() itself triggers additional TPM events that then can't be obtained using this protocol. The platform provides a mechanism for the OS to obtain these events by recording them to a separate UEFI configuration table which the OS can then map. Unfortunately this table isn't self describing in terms of providing its length, so we need to parse the events inside it to figure out how long it is. Since the table isn't mapped at this point, we need to extend the length calculation function to be able to map the event as it goes along. (Fixes by Bartosz Szczepanek <bsz@semihalf.com>) Signed-off-by: Matthew Garrett <mjg59@google.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Bartosz Szczepanek <bsz@semihalf.com> Tested-by: Bartosz Szczepanek <bsz@semihalf.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-06-24tpm: Abstract crypto agile event size calculationsMatthew Garrett1-0/+68
We need to calculate the size of crypto agile events in multiple locations, including in the EFI boot stub. The easiest way to do this is to put it in a header file as an inline and leave a wrapper to ensure we don't end up with multiple copies of it embedded in the existing code. Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Bartosz Szczepanek <bsz@semihalf.com> Tested-by: Bartosz Szczepanek <bsz@semihalf.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-02-13tpm: rename and export tpm2_digest and tpm2_algorithmsRoberto Sassu1-7/+2
Rename tpm2_* to tpm_* and move the definitions to include/linux/tpm.h so that these can be used by other kernel subsystems (e.g. IMA). Also, set the length of the digest array in tpm_digest to a new constant named TPM_MAX_DIGEST_SIZE, equal to SHA512_DIGEST_SIZE. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Acked-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2019-02-13tpm: add _head suffix to tcg_efi_specid_event and tcg_pcr_event2Roberto Sassu1-8/+4
TCG defines two structures, TCG_EfiSpecIDEventStruct and TCG_PCR_EVENT2, which contain variable-sized arrays in the middle of the definition. Since these structures are not suitable for type casting, this patch removes structure members after the variable-sized arrays and adds the _head suffix to the structure name, to indicate that the renamed structures do not contain all fields defined by TCG. Lastly, given that variable-sized arrays are now in the last position, and given that the size of the arrays cannot be determined in advance, this patch also sets the size of those arrays to zero and removes the definition of TPM2_ACTIVE_PCR_BANKS. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Tested-by: Nayna Jain <nayna@linux.ibm.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2018-01-08tpm: add event log format versionThiebaud Weksteen1-0/+3
Although defined as part of the TCG EFI specification, we add these definitions here so that any event log provider may reference them. Signed-off-by: Thiebaud Weksteen <tweek@google.com> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
2018-01-08tpm: move tpm_eventlog.h outside of drivers folderThiebaud Weksteen1-0/+121
The generic definitions of data structures in tpm_eventlog.h are required by other part of the kernel (namely, the EFI stub). Signed-off-by: Thiebaud Weksteen <tweek@google.com> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Javier Martinez Canillas <javierm@redhat.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>