[LTP] [PATCH v4 4/4] ima_tpm.sh: Fix calculating PCR aggregate
Petr Vorel
pvorel@suse.cz
Wed Sep 30 18:02:14 CEST 2020
for TPM 2.0 and support more evmctl versions.
Because exporting PCR registers for TPM 2.0 has not been upstreamed [1],
we use user space code, which requires evmctl >= 1.3.1 and tsspcrread.
Using evmctl allows to test for TPM devices which does not export event
log (/sys/kernel/security/tpm0/binary_bios_measurements).
For TPM 1.2 read tpm0 device pcrs file from kernel. (tss1pcrread could
be also used, but it's not yet packaged by distros.)
For old kernels which use SHA1/MD5, any evmctl version is required (evmctl
ima_measurement was introduced in very old v0.7), but
* newer sysctl path /sys/class/tpm/tpm0/device/pcrs requires evmctl 1.1
* using ima_policy=tcb requires 1.3.1 due --ignore-violations
We now support output format of ima_measurement command for various
evmctl versions:
* 1.3: "sha256: TPM PCR-10:" (or other algorithm, e.g. "sha1:")
* 1.1-1.2.1: "HW PCR-10:" (the only previously supported format)
* 0.7-1.0: "PCR-10:"
NOTE: we ignore evmctl failure for evmctl < 1.3.1 (missing --ignore-violations,
also evmctl < 1.1 fails with "PCRAgg does not match PCR-10")
[1] https://patchwork.kernel.org/patch/11759729/
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
changes v3->v4:
* use --ignore-violations if evmctl >= 1.3.1 available
* check error only for 1.3.1, for others check only the result
* check for ima_policy=tcb (or ima_tcb) and require 1.3.1 if used
(to get --ignore-violations)
.../security/integrity/ima/tests/ima_setup.sh | 14 +-
.../security/integrity/ima/tests/ima_tpm.sh | 151 +++++++++++++-----
2 files changed, 118 insertions(+), 47 deletions(-)
diff --git a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
index 83ea62d4f..b801c4371 100644
--- a/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_setup.sh
@@ -93,7 +93,7 @@ require_ima_policy_content()
fi
}
-require_ima_policy_cmdline()
+check_ima_policy_cmdline()
{
local policy="$1"
local i
@@ -101,10 +101,18 @@ require_ima_policy_cmdline()
grep -q "ima_$policy" /proc/cmdline && return
for i in $(cat /proc/cmdline); do
if echo "$i" | grep -q '^ima_policy='; then
- echo "$i" | grep -q -e "|[ ]*$policy" -e "$policy[ ]*|" -e "=$policy" && return
+ echo "$i" | grep -q -e "|[ ]*$policy" -e "$policy[ ]*|" -e "=$policy" && return 0
fi
done
- tst_brk TCONF "IMA measurement tests require builtin IMA $policy policy (e.g. ima_policy=$policy kernel parameter)"
+ return 1
+}
+
+require_ima_policy_cmdline()
+{
+ local policy="$1"
+
+ check_ima_policy_cmdline $policy || \
+ tst_brk TCONF "IMA measurement tests require builtin IMA $policy policy (e.g. ima_policy=$policy kernel parameter)"
}
mount_helper()
diff --git a/testcases/kernel/security/integrity/ima/tests/ima_tpm.sh b/testcases/kernel/security/integrity/ima/tests/ima_tpm.sh
index ce35a8e27..43d330802 100755
--- a/testcases/kernel/security/integrity/ima/tests/ima_tpm.sh
+++ b/testcases/kernel/security/integrity/ima/tests/ima_tpm.sh
@@ -13,7 +13,8 @@ TST_SETUP="setup"
. ima_setup.sh
EVMCTL_REQUIRED='1.3.1'
-ERRMSG_EVMCTL="install evmctl >= $EVMCTL_REQUIRED"
+ERRMSG_EVMCTL="=> install evmctl >= $EVMCTL_REQUIRED"
+ERRMSG_TPM="TPM hardware support not enabled in kernel or no TPM chip found"
setup()
{
@@ -101,11 +102,91 @@ get_tpm_version()
fi
}
+read_pcr_tpm1()
+{
+ local pcr_path="/sys/class/tpm/tpm0/device/pcrs"
+ local evmctl_required="1.1"
+ local pcr hash
+
+ if [ ! -f "$pcrs_path" ]; then
+ pcrs_path="/sys/class/misc/tpm0/device/pcrs"
+ elif ! check_evmctl $evmctl_required; then
+ tst_res TCONF "evmctl >= $evmctl_required required"
+ return 1
+ fi
+
+ if [ ! -f "$pcr_path" ]; then
+ tst_res TCONF "missing PCR file $pcrs_path ($ERRMSG_TPM)"
+ return
+ fi
+
+ while read line; do
+ pcr="$(echo $line | cut -d':' -f1)"
+ hash="$(echo $line | cut -d':' -f2 | awk '{ gsub (" ", "", $0); print tolower($0) }')"
+ echo "$pcr: $hash"
+ done < $pcr_path
+}
+
+# NOTE: TPM 1.2 would require to use tss1pcrread which is not fully adopted
+# by distros yet.
+read_pcr_tpm2()
+{
+ local pcrmax=23
+ local pcrread="tsspcrread -halg $ALGORITHM"
+ local i pcr
+
+ tst_check_cmds tsspcrread || return 1
+
+ for i in $(seq 0 $pcrmax); do
+ pcr=$($pcrread -ha "$i" -ns)
+ if [ $? -ne 0 ]; then
+ tst_brk TBROK "tsspcrread failed: $pcr"
+ fi
+ printf "PCR-%02d: %s\n" $i "$pcr"
+ done
+}
+
+get_pcr10_aggregate()
+{
+ local params pcr
+ local msg="$ERRMSG_EVMCTL"
+ local res=TCONF
+
+ if [ -z "$MISSING_EVMCTL" ]; then
+ params="--ignore-violations"
+ msg=
+ res=TFAIL
+ elif check_ima_policy_cmdline "tcb"; then
+ tst_res TCONF "using builtin IMA TCB policy $ERRMSG_EVMCTL"
+ return
+ fi
+
+ evmctl -v ima_measurement $params $BINARY_MEASUREMENTS > hash.txt 2>&1
+ if [ $? -ne 0 -a -z "$MISSING_EVMCTL" ]; then
+ tst_res TFAIL "evmctl failed $ERRMSG_EVMCTL"
+ tst_res TINFO "hash file:"
+ cat hash.txt >&2
+ return
+ fi
+
+ pcr=$(grep -E "^($ALGORITHM: )*PCRAgg.*:" hash.txt \
+ | awk '{print $NF}')
+
+ if [ -z "$pcr" ]; then
+ tst_res $res "failed to find aggregate PCR-10 $msg"
+ tst_res TINFO "hash file:"
+ cat hash.txt >&2
+ return
+ fi
+
+ echo "$pcr"
+}
+
test1_virtual_tpm()
{
local zero=$(echo $DIGEST | awk '{gsub(/./, "0")}; {print}')
- tst_res TINFO "TPM hardware support not enabled in kernel or no TPM chip found, testing TPM-bypass"
+ tst_res TINFO "$ERRMSG_TPM, testing TPM-bypass"
if [ "$DIGEST" = "$zero" ]; then
tst_res TPASS "bios boot aggregate is $zero"
@@ -122,7 +203,7 @@ test1_hw_tpm()
if [ "$MISSING_EVMCTL" = 1 ]; then
if [ ! -f "$tpm_bios" ]; then
- tst_res TCONF "missing $tpm_bios, $ERRMSG_EVMCTL"
+ tst_res TCONF "missing $tpm_bios $ERRMSG_EVMCTL"
return
fi
tst_check_cmds ima_boot_aggregate || return
@@ -151,57 +232,39 @@ test1()
[ -z "$TPM_VERSION" ] && test1_virtual_tpm || test1_hw_tpm
}
-# Probably cleaner to programmatically read the PCR values directly
-# from the TPM, but that would require a TPM library. For now, use
-# the PCR values from /sys/devices.
-validate_pcr()
+test2()
{
- tst_res TINFO "verify PCR (Process Control Register)"
+ local hash pcr_aggregate
- local dev_pcrs="$1"
- local pcr hash aggregate_pcr
+ tst_res TINFO "verify PCR values"
- aggregate_pcr="$(evmctl -v ima_measurement $BINARY_MEASUREMENTS 2>&1 | \
- grep 'HW PCR-10:' | awk '{print $3}')"
- if [ -z "$aggregate_pcr" ]; then
- tst_res TFAIL "failed to get PCR-10"
- return 1
+ if [ -z "$TPM_VERSION" ]; then
+ tst_brk TCONF "TMP version not detected ($ERRMSG_TPM)"
fi
- while read line; do
- pcr="$(echo $line | cut -d':' -f1)"
- if [ "$pcr" = "PCR-10" ]; then
- hash="$(echo $line | cut -d':' -f2 | awk '{ gsub (" ", "", $0); print tolower($0) }')"
- [ "$hash" = "$aggregate_pcr" ]
- return $?
- fi
- done < $dev_pcrs
- return 1
-}
-
-test2()
-{
- tst_res TINFO "verify PCR values"
- tst_check_cmds evmctl || return
+ if [ "$ALGORITHM" = "sha1" -a "$MISSING_EVMCTL" = 1 ]; then
+ tst_check_cmds evmctl || return 1
+ fi
- tst_res TINFO "evmctl version: $(evmctl --version)"
+ read_pcr_tpm$TPM_VERSION > pcr.txt || return
+ hash=$(grep "^PCR-10" pcr.txt | cut -d' ' -f2)
+ if [ -z "$hash" ]; then
+ tst_res TFAIL "PCR-10 hash not found"
+ cat pcr.txt
+ return
+ fi
+ tst_res TINFO "real PCR-10: '$hash'"
- local pcrs_path="/sys/class/tpm/tpm0/device/pcrs"
- if [ -f "$pcrs_path" ]; then
- tst_res TINFO "new PCRS path, evmctl >= 1.1 required"
- else
- pcrs_path="/sys/class/misc/tpm0/device/pcrs"
+ pcr_aggregate="$(get_pcr10_aggregate)"
+ if [ -z "$pcr_aggregate" ]; then
+ return
fi
+ tst_res TINFO "aggregate PCR-10: '$hash'"
- if [ -f "$pcrs_path" ]; then
- validate_pcr $pcrs_path
- if [ $? -eq 0 ]; then
- tst_res TPASS "aggregate PCR value matches real PCR value"
- else
- tst_res TFAIL "aggregate PCR value does not match real PCR value"
- fi
+ if [ "$hash" = "$pcr_aggregate" ]; then
+ tst_res TPASS "aggregate PCR value matches real PCR value"
else
- tst_res TCONF "TPM Hardware Support not enabled in kernel or no TPM chip found"
+ tst_res TFAIL "aggregate PCR value does not match real PCR value"
fi
}
--
2.28.0
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