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authorStefan Berger <stefanb@linux.ibm.com>2021-03-10 17:19:15 -0500
committerJarkko Sakkinen <jarkko@kernel.org>2021-04-14 16:30:30 +0300
commit3dcd15665aca80197333500a4be3900948afccc1 (patch)
tree5237a95737241ace81cf57a951057e127a21d8c9 /drivers/char
parent48cff270b037022e37835d93361646205ca25101 (diff)
downloadlinux-3dcd15665aca80197333500a4be3900948afccc1.tar.bz2
tpm: acpi: Check eventlog signature before using it
Check the eventlog signature before using it. This avoids using an empty log, as may be the case when QEMU created the ACPI tables, rather than probing the EFI log next. This resolves an issue where the EFI log was empty since an empty ACPI log was used. Cc: stable@vger.kernel.org Fixes: 85467f63a05c ("tpm: Add support for event log pointer found in TPM2 ACPI table") Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tpm/eventlog/acpi.c33
1 files changed, 32 insertions, 1 deletions
diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
index 3633ed70f48f..1b18ce5ebab1 100644
--- a/drivers/char/tpm/eventlog/acpi.c
+++ b/drivers/char/tpm/eventlog/acpi.c
@@ -41,6 +41,27 @@ struct acpi_tcpa {
};
};
+/* Check that the given log is indeed a TPM2 log. */
+static bool tpm_is_tpm2_log(void *bios_event_log, u64 len)
+{
+ struct tcg_efi_specid_event_head *efispecid;
+ struct tcg_pcr_event *event_header;
+ int n;
+
+ if (len < sizeof(*event_header))
+ return false;
+ len -= sizeof(*event_header);
+ event_header = bios_event_log;
+
+ if (len < sizeof(*efispecid))
+ return false;
+ efispecid = (struct tcg_efi_specid_event_head *)event_header->event;
+
+ n = memcmp(efispecid->signature, TCG_SPECID_SIG,
+ sizeof(TCG_SPECID_SIG));
+ return n == 0;
+}
+
/* read binary bios log */
int tpm_read_log_acpi(struct tpm_chip *chip)
{
@@ -52,6 +73,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
struct acpi_table_tpm2 *tbl;
struct acpi_tpm2_phy *tpm2_phy;
int format;
+ int ret;
log = &chip->log;
@@ -112,6 +134,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
log->bios_event_log_end = log->bios_event_log + len;
+ ret = -EIO;
virt = acpi_os_map_iomem(start, len);
if (!virt)
goto err;
@@ -119,11 +142,19 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
memcpy_fromio(log->bios_event_log, virt, len);
acpi_os_unmap_iomem(virt, len);
+
+ if (chip->flags & TPM_CHIP_FLAG_TPM2 &&
+ !tpm_is_tpm2_log(log->bios_event_log, len)) {
+ /* try EFI log next */
+ ret = -ENODEV;
+ goto err;
+ }
+
return format;
err:
kfree(log->bios_event_log);
log->bios_event_log = NULL;
- return -EIO;
+ return ret;
}