test: check if we can use SHA1 MD for signing before using it

Some distributions have started phasing out SHA1, which breaks
the systemd-measure test case in its current form. Let's make sure we
can use SHA1 for signing beforehand to mitigate this.

Spotted on RHEL 9, where SHA1 signatures are disallowed by [0]:
```
openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out "/tmp/pcrsign-private.pem"
...
openssl rsa -pubout -in "/tmp/pcrsign-private.pem" -out "/tmp/pcrsign-public.pem"
writing RSA key
/usr/lib/systemd/systemd-measure sign --current --bank=sha1 --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem"
Failed to initialize signature context.
```

[0] https://gitlab.com/redhat/centos-stream/rpms/openssl/-/blob/c9s/0049-Selectively-disallow-SHA1-signatures.patch

diff --git a/test/units/testsuite-70.sh b/test/units/testsuite-70.sh
index b1cf7e83c4b5b5d37fcd3428ff3a1bac49e4a2dc..89cd2a3f827ad9b3193a9580a6e9f8cfbbc54c99 100755 (executable)
--- a/test/units/testsuite-70.sh
+++ b/test/units/testsuite-70.sh
@@ -102,8 +102,17 @@ if [ -e /usr/lib/systemd/systemd-measure ] && \
     openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -out "/tmp/pcrsign-private.pem"
     openssl rsa -pubout -in "/tmp/pcrsign-private.pem" -out "/tmp/pcrsign-public.pem"
 
+    MEASURE_BANKS=("--bank=sha256")
+    # Check if SHA1 signatures are supported
+    #
+    # Some distros have started phasing out SHA1, so make sure the SHA1
+    # signatures are supported before trying to use them.
+    if echo hello | openssl dgst -sign /tmp/pcrsign-private.pem -sha1 >/dev/null; then
+        MEASURE_BANKS+=("--bank=sha1")
+    fi
+
     # Sign current PCR state with it
-    /usr/lib/systemd/systemd-measure sign --current --bank=sha1 --bank=sha256 --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem" --phase=: | tee "/tmp/pcrsign.sig"
+    /usr/lib/systemd/systemd-measure sign --current "${MEASURE_BANKS[@]}" --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem" --phase=: | tee "/tmp/pcrsign.sig"
     dd if=/dev/urandom of=/tmp/pcrtestdata bs=1024 count=64
     systemd-creds encrypt /tmp/pcrtestdata /tmp/pcrtestdata.encrypted --with-key=host+tpm2-with-public-key --tpm2-public-key="/tmp/pcrsign-public.pem"
     systemd-creds decrypt /tmp/pcrtestdata.encrypted - --tpm2-signature="/tmp/pcrsign.sig" | cmp - /tmp/pcrtestdata
@@ -113,7 +122,7 @@ if [ -e /usr/lib/systemd/systemd-measure ] && \
     systemd-creds decrypt /tmp/pcrtestdata.encrypted - --tpm2-signature="/tmp/pcrsign.sig" > /dev/null && { echo 'unexpected success'; exit 1; }
 
     # Sign new PCR state, decrypting should work now.
-    /usr/lib/systemd/systemd-measure sign --current --bank=sha1 --bank=sha256 --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem" --phase=: > "/tmp/pcrsign.sig2"
+    /usr/lib/systemd/systemd-measure sign --current "${MEASURE_BANKS[@]}" --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem" --phase=: > "/tmp/pcrsign.sig2"
     systemd-creds decrypt /tmp/pcrtestdata.encrypted - --tpm2-signature="/tmp/pcrsign.sig2" | cmp - /tmp/pcrtestdata
 
     # Now, do the same, but with a cryptsetup binding
@@ -135,7 +144,7 @@ if [ -e /usr/lib/systemd/systemd-measure ] && \
     SYSTEMD_CRYPTSETUP_USE_TOKEN_MODULE=1 /usr/lib/systemd/systemd-cryptsetup attach test-volume2 $img - tpm2-device=auto,tpm2-signature="/tmp/pcrsign.sig2",headless=1 && { echo 'unexpected success'; exit 1; }
 
     # But once we sign the current PCRs, we should be able to unlock again
-    /usr/lib/systemd/systemd-measure sign --current --bank=sha1 --bank=sha256 --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem" --phase=: > "/tmp/pcrsign.sig3"
+    /usr/lib/systemd/systemd-measure sign --current "${MEASURE_BANKS[@]}" --private-key="/tmp/pcrsign-private.pem" --public-key="/tmp/pcrsign-public.pem" --phase=: > "/tmp/pcrsign.sig3"
     SYSTEMD_CRYPTSETUP_USE_TOKEN_MODULE=0 /usr/lib/systemd/systemd-cryptsetup attach test-volume2 $img - tpm2-device=auto,tpm2-signature="/tmp/pcrsign.sig3",headless=1
     /usr/lib/systemd/systemd-cryptsetup detach test-volume2
     SYSTEMD_CRYPTSETUP_USE_TOKEN_MODULE=1 /usr/lib/systemd/systemd-cryptsetup attach test-volume2 $img - tpm2-device=auto,tpm2-signature="/tmp/pcrsign.sig3",headless=1