tpm: eventlog: Replace zero-length array with flexible-array member

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>

tpm: tpm2_bios_measurements_next should increase position index

If .next function does not change position index,
following .show function will repeat output related
to current position index.

For /sys/kernel/security/tpm0/binary_bios_measurements:
1) read after lseek beyound end of file generates whole last line.
2) read after lseek to middle of last line generates
expected end of last line and unexpected whole last line once again.

Cc: stable@vger.kernel.org # 4.19.x
Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code ...")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

tpm: Reserve the TPM final events table

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>

tpm: Abstract crypto agile event size calculations

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>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tpm: Fix the type of the return value in calc_tpm2_event_size()

calc_tpm2_event_size() has an invalid signature because
it returns a 'size_t' where as its signature says that
it returns 'int'.

Cc: <stable@vger.kernel.org>
Fixes: 4d23cc323cdb ("tpm: add securityfs support for TPM 2.0 firmware event log")
Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

tpm: add _head suffix to tcg_efi_specid_event and tcg_pcr_event2

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>

tpm: Move eventlog declarations to its own header

Reduce the size of tpm.h by moving eventlog declarations to a separate
header.

Signed-off-by: Thiebaud Weksteen <tweek@google.com>
Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.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>

tpm: Move eventlog files to a subdirectory

Signed-off-by: Thiebaud Weksteen <tweek@google.com>
Suggested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.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>