test: find out tpm device rather than hardcoding it in TEST-92-TPM2-SWTPM

Looks like the device might change depending on the boot sequence, so
discover it in the test rather than hardcoding it to /dev/tpmrm0.

Fixes https://github.com/systemd/systemd/issues/43210

Follow-up for 1b1900a6f3162b3f16b6779bdcca9ec0f9aa11e9

diff --git a/test/units/TEST-92-TPM2-SWTPM.sh b/test/units/TEST-92-TPM2-SWTPM.sh
index 8e2c7d1143280aa8840a26591f6da4a7c019e0ca..b8e0df5a8b85017513c8f949191faef9e38d39ed 100755 (executable)
--- a/test/units/TEST-92-TPM2-SWTPM.sh
+++ b/test/units/TEST-92-TPM2-SWTPM.sh
@@ -23,6 +23,7 @@ CRED=/var/lib/systemd-tpm2-swtpm-test.cred
 PLAINTEXT="swtpm round-trip"
 # Marker (SWTPM_MANUFACTURED_MARKER) that manufacture_swtpm() indicates completion with.
 MARKER=.manufactured
+TPM2_DEVICE=
 
 if [[ -n "${ASAN_OPTIONS:-}" ]]; then
     # swtpm_setup is not built with sanitizers, but does NSS lookups that pull in the ASan-instrumented
@@ -37,9 +38,25 @@ if [[ ! -x /usr/lib/systemd/systemd-tpm2-swtpm ]] || ! command -v swtpm >/dev/nu
 fi
 
 assert_swtpm_up() {
+    local deadline tpm_device tpm_index tpmrm_device tpmrm_devices
+
     systemctl is-active systemd-tpm2-swtpm.service
-    timeout 30 bash -c 'until [[ -c /dev/tpmrm0 ]]; do sleep 1; done'
-    test -c /dev/tpm0
+
+    deadline=$((SECONDS + 30))
+    while (( SECONDS < deadline )); do
+        mapfile -t tpmrm_devices < <(compgen -G '/sys/class/tpmrm/tpmrm*' || :)
+        ((${#tpmrm_devices[@]} == 1)) && break
+        sleep .1
+    done
+    assert_eq "${#tpmrm_devices[@]}" 1
+
+    # The old initrd device number may still be reserved when the host swtpm starts, so do not assume tpm0.
+    tpmrm_device="${tpmrm_devices[0]##*/}"
+    tpm_index="${tpmrm_device#tpmrm}"
+    TPM2_DEVICE="/dev/$tpmrm_device"
+    tpm_device="/dev/tpm$tpm_index"
+
+    udevadm wait --timeout=30 --settle "$TPM2_DEVICE" "$tpm_device"
     # No firmware TPM here, so has-tpm2 reports "partial"; assert the software driver is present.
     assert_in '\+driver' "$(systemd-analyze has-tpm2 || :)"
 }
@@ -58,8 +75,8 @@ case "$REBOOT_COUNT" in
         assert_swtpm_up
         # Seal a secret to the software TPM and keep the blob for the next boot.
         echo -n "$PLAINTEXT" >/tmp/swtpm-plaintext
-        systemd-creds encrypt --name= --with-key=tpm2 /tmp/swtpm-plaintext "$CRED"
-        systemd-creds decrypt --name= "$CRED" - | cmp /tmp/swtpm-plaintext -
+        systemd-creds --tpm2-device="$TPM2_DEVICE" encrypt --name= --with-key=tpm2 /tmp/swtpm-plaintext "$CRED"
+        systemd-creds --tpm2-device="$TPM2_DEVICE" decrypt --name= "$CRED" - | cmp /tmp/swtpm-plaintext -
         systemctl_final reboot
         exec sleep infinity
         ;;
@@ -67,7 +84,7 @@ case "$REBOOT_COUNT" in
         assert_swtpm_up
         # Persistence: the TPM state survived the reboot on the ESP, so the blob still unseals.
         echo -n "$PLAINTEXT" >/tmp/swtpm-plaintext
-        systemd-creds decrypt --name= "$CRED" - | cmp /tmp/swtpm-plaintext -
+        systemd-creds --tpm2-device="$TPM2_DEVICE" decrypt --name= "$CRED" - | cmp /tmp/swtpm-plaintext -
 
         # Mimic a manufacture interrupted after swtpm began writing TPM state but before the marker: stop
         # swtpm, drop everything except the three config files, then leave a partial/corrupt state file
@@ -91,8 +108,8 @@ case "$REBOOT_COUNT" in
         test -e "$statedir/$MARKER"
         test -e "$statedir/issuer-certificate.pem"
         echo -n "$PLAINTEXT" >/tmp/swtpm-plaintext
-        systemd-creds encrypt --name= --with-key=tpm2 /tmp/swtpm-plaintext /tmp/swtpm-new.cred
-        systemd-creds decrypt --name= /tmp/swtpm-new.cred - | cmp /tmp/swtpm-plaintext -
+        systemd-creds --tpm2-device="$TPM2_DEVICE" encrypt --name= --with-key=tpm2 /tmp/swtpm-plaintext /tmp/swtpm-new.cred
+        systemd-creds --tpm2-device="$TPM2_DEVICE" decrypt --name= /tmp/swtpm-new.cred - | cmp /tmp/swtpm-plaintext -
         touch /testok
         ;;
     *)