tpm: Use managed allocation for bios event log

Since the bios event log is freed in the device release function,
let devres handle the deallocation. This will allow other memory
allocation/mapping functions to be used for the bios event log.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

tpm: efi: Use local variable for calculating final log size

When tpm_read_log_efi is called multiple times, which happens when
one loads and unloads a TPM2 driver multiple times, then the global
variable efi_tpm_final_log_size will at some point become a negative
number due to the subtraction of final_events_preboot_size occurring
each time. Use a local variable to avoid this integer underflow.

The following issue is now resolved:

Mar 8 15:35:12 hibinst kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Mar 8 15:35:12 hibinst kernel: Workqueue: tpm-vtpm vtpm_proxy_work [tpm_vtpm_proxy]
Mar 8 15:35:12 hibinst kernel: RIP: 0010:__memcpy+0x12/0x20
Mar 8 15:35:12 hibinst kernel: Code: 00 b8 01 00 00 00 85 d2 74 0a c7 05 44 7b ef 00 0f 00 00 00 c3 cc cc cc 66 66 90 66 90 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 <f3> 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 f3 a4
Mar 8 15:35:12 hibinst kernel: RSP: 0018:ffff9ac4c0fcfde0 EFLAGS: 00010206
Mar 8 15:35:12 hibinst kernel: RAX: ffff88f878cefed5 RBX: ffff88f878ce9000 RCX: 1ffffffffffffe0f
Mar 8 15:35:12 hibinst kernel: RDX: 0000000000000003 RSI: ffff9ac4c003bff9 RDI: ffff88f878cf0e4d
Mar 8 15:35:12 hibinst kernel: RBP: ffff9ac4c003b000 R08: 0000000000001000 R09: 000000007e9d6073
Mar 8 15:35:12 hibinst kernel: R10: ffff9ac4c003b000 R11: ffff88f879ad3500 R12: 0000000000000ed5
Mar 8 15:35:12 hibinst kernel: R13: ffff88f878ce9760 R14: 0000000000000002 R15: ffff88f77de7f018
Mar 8 15:35:12 hibinst kernel: FS: 0000000000000000(0000) GS:ffff88f87bd00000(0000) knlGS:0000000000000000
Mar 8 15:35:12 hibinst kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Mar 8 15:35:12 hibinst kernel: CR2: ffff9ac4c003c000 CR3: 00000001785a6004 CR4: 0000000000060ee0
Mar 8 15:35:12 hibinst kernel: Call Trace:
Mar 8 15:35:12 hibinst kernel: tpm_read_log_efi+0x152/0x1a7
Mar 8 15:35:12 hibinst kernel: tpm_bios_log_setup+0xc8/0x1c0
Mar 8 15:35:12 hibinst kernel: tpm_chip_register+0x8f/0x260
Mar 8 15:35:12 hibinst kernel: vtpm_proxy_work+0x16/0x60 [tpm_vtpm_proxy]
Mar 8 15:35:12 hibinst kernel: process_one_work+0x1b4/0x370
Mar 8 15:35:12 hibinst kernel: worker_thread+0x53/0x3e0
Mar 8 15:35:12 hibinst kernel: ? process_one_work+0x370/0x370

Cc: stable@vger.kernel.org
Fixes: 166a2809d65b ("tpm: Don't duplicate events from the final event log in the TCG2 log")
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

tpm: efi: Don't create binary_bios_measurements file for an empty log

Mimic the pre-existing ACPI and Device Tree event log behavior by not
creating the binary_bios_measurements file when the EFI TPM event log is
empty.

This fixes the following NULL pointer dereference that can occur when
reading /sys/kernel/security/tpm0/binary_bios_measurements after the
kernel received an empty event log from the firmware:

BUG: kernel NULL pointer dereference, address: 000000000000002c
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 2 PID: 3932 Comm: fwupdtpmevlog Not tainted 5.9.0-00003-g629990edad62 #17
Hardware name: LENOVO 20LCS03L00/20LCS03L00, BIOS N27ET38W (1.24 ) 11/28/2019
RIP: 0010:tpm2_bios_measurements_start+0x3a/0x550
Code: 54 53 48 83 ec 68 48 8b 57 70 48 8b 1e 65 48 8b 04 25 28 00 00 00 48 89 45 d0 31 c0 48 8b 82 c0 06 00 00 48 8b 8a c8 06 00 00 <44> 8b 60 1c 48 89 4d a0 4c 89 e2 49 83 c4 20 48 83 fb 00 75 2a 49
RSP: 0018:ffffa9c901203db0 EFLAGS: 00010246
RAX: 0000000000000010 RBX: 0000000000000000 RCX: 0000000000000010
RDX: ffff8ba1eb99c000 RSI: ffff8ba1e4ce8280 RDI: ffff8ba1e4ce8258
RBP: ffffa9c901203e40 R08: ffffa9c901203dd8 R09: ffff8ba1ec443300
R10: ffffa9c901203e50 R11: 0000000000000000 R12: ffff8ba1e4ce8280
R13: ffffa9c901203ef0 R14: ffffa9c901203ef0 R15: ffff8ba1e4ce8258
FS: 00007f6595460880(0000) GS:ffff8ba1ef880000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000002c CR3: 00000007d8d18003 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? __kmalloc_node+0x113/0x320
? kvmalloc_node+0x31/0x80
seq_read+0x94/0x420
vfs_read+0xa7/0x190
ksys_read+0xa7/0xe0
__x64_sys_read+0x1a/0x20
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9

In this situation, the bios_event_log pointer in the tpm_bios_log struct
was not NULL but was equal to the ZERO_SIZE_PTR (0x10) value. This was
due to the following kmemdup() in tpm_read_log_efi():

int tpm_read_log_efi(struct tpm_chip *chip)
{
...
/* malloc EventLog space */
log->bios_event_log = kmemdup(log_tbl->log, log_size, GFP_KERNEL);
if (!log->bios_event_log) {
ret = -ENOMEM;
goto out;
}
...
}

When log_size is zero, due to an empty event log from firmware,
ZERO_SIZE_PTR is returned from kmemdup(). Upon a read of the
binary_bios_measurements file, the tpm2_bios_measurements_start()
function does not perform a ZERO_OR_NULL_PTR() check on the
bios_event_log pointer before dereferencing it.

Rather than add a ZERO_OR_NULL_PTR() check in functions that make use of
the bios_event_log pointer, simply avoid creating the
binary_bios_measurements_file as is done in other event log retrieval
backends.

Explicitly ignore all of the events in the final event log when the main
event log is empty. The list of events in the final event log cannot be
accurately parsed without referring to the first event in the main event
log (the event log header) so the final event log is useless in such a
situation.

Fixes: 58cc1e4faf10 ("tpm: parse TPM event logs based on EFI table")
Link: https://lore.kernel.org/linux-integrity/E1FDCCCB-CA51-4AEE-AC83-9CDE995EAE52@canonical.com/
Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reported-by: Kenneth R. Crudup <kenny@panix.com>
Reported-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: Thiébaud Weksteen <tweek@google.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

tpm: Don't duplicate events from the final event log in the TCG2 log

After the first call to GetEventLog() on UEFI systems using the TCG2
crypto agile log format, any further log events (other than those
triggered by ExitBootServices()) will be logged in both the main log and
also in the Final Events Log. While the kernel only calls GetEventLog()
immediately before ExitBootServices(), we can't control whether earlier
parts of the boot process have done so. This will result in log entries
that exist in both logs, and so the current approach of simply appending
the Final Event Log to the main log will result in events being
duplicated.

We can avoid this problem by looking at the size of the Final Event Log
just before we call ExitBootServices() and exporting this to the main
kernel. The kernel can then skip over all events that occured before
ExitBootServices() and only append events that were not also logged to
the main log.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Reported-by: Joe Richey <joerichey@google.com>
Suggested-by: Joe Richey <joerichey@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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: Append the final event log to the TPM event log

Any events that are logged after GetEventsLog() is called are logged to
the EFI Final Events table. These events are defined as being in the
crypto agile log format, so we can just append them directly to the
existing log if it's in the same format. In theory we can also construct
old-style SHA1 log entries for devices that only return logs in that
format, but EDK2 doesn't generate the final event log in that case so
it doesn't seem worth it at the moment.

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: replace kmalloc() + memcpy() with kmemdup()

Use kmemdup rather than duplicating its implementation.

Signed-off-by: Ji-Hun Kim <ji_hun.kim@samsung.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkine@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkine@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>