ssh signing: verify ssh-keygen in test prereq

Do a full ssh signing, find-principals and verify operation in the test
prereq's to make sure ssh-keygen works as expected. Only generating the
keys and verifying its presence is not sufficient in some situations.
One example was ssh-keygen creating unusable ssh keys in cygwin because
of unsafe default permissions for the key files. The other a broken
openssh 8.7 that segfaulted on any find-principals operation. This
extended prereq check avoids future test breakages in case ssh-keygen or
any environment behaviour changes.

Signed-off-by: Fabian Stelzer <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: FStelzer

t/lib-gpg.sh

@@ -109,34 +109,61 @@ test_lazy_prereq GPGSSH '
 	echo $ssh_version | grep -q "find-principals:missing signature file"
 	test $? = 0 || exit 1;
 
-	# some broken versions of ssh-keygen segfault on find-principals;
-	# avoid testing with them.
-	ssh-keygen -Y find-principals -f /dev/null -s /dev/null
-	test $? = 139 && exit 1
-
+	# Setup some keys and an allowed signers file
 	mkdir -p "${GNUPGHOME}" &&
 	chmod 0700 "${GNUPGHOME}" &&
 	(setfacl -k "${GNUPGHOME}" 2>/dev/null || true) &&
 	ssh-keygen -t ed25519 -N "" -C "git ed25519 key" -f "${GPGSSH_KEY_PRIMARY}" >/dev/null &&
-	echo "\"principal with number 1\" $(cat "${GPGSSH_KEY_PRIMARY}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
 	ssh-keygen -t rsa -b 2048 -N "" -C "git rsa2048 key" -f "${GPGSSH_KEY_SECONDARY}" >/dev/null &&
-	echo "\"principal with number 2\" $(cat "${GPGSSH_KEY_SECONDARY}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
 	ssh-keygen -t ed25519 -N "${GPGSSH_KEY_PASSPHRASE}" -C "git ed25519 encrypted key" -f "${GPGSSH_KEY_WITH_PASSPHRASE}" >/dev/null &&
-	echo "\"principal with number 3\" $(cat "${GPGSSH_KEY_WITH_PASSPHRASE}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
-	ssh-keygen -t ed25519 -N "" -C "git ed25519 key" -f "${GPGSSH_KEY_UNTRUSTED}" >/dev/null
+	ssh-keygen -t ed25519 -N "" -C "git ed25519 key" -f "${GPGSSH_KEY_UNTRUSTED}" >/dev/null &&
+
+	cat >"${GPGSSH_ALLOWED_SIGNERS}" <<-EOF &&
+	"principal with number 1" $(cat "${GPGSSH_KEY_PRIMARY}.pub")"
+	"principal with number 2" $(cat "${GPGSSH_KEY_SECONDARY}.pub")"
+	"principal with number 3" $(cat "${GPGSSH_KEY_WITH_PASSPHRASE}.pub")"
+	EOF
+
+	# Verify if at least one key and ssh-keygen works as expected
+	echo "testpayload" |
+	ssh-keygen -Y sign -n "git" -f "${GPGSSH_KEY_PRIMARY}" >gpgssh_prereq.sig &&
+	ssh-keygen -Y find-principals -f "${GPGSSH_ALLOWED_SIGNERS}" -s gpgssh_prereq.sig &&
+	echo "testpayload" |
+	ssh-keygen -Y verify -n "git" -f "${GPGSSH_ALLOWED_SIGNERS}" -I "principal with number 1" -s gpgssh_prereq.sig
 '
 
 test_lazy_prereq GPGSSH_VERIFYTIME '
 	# Check if ssh-keygen has a verify-time option by passing an invalid date to it
 	ssh-keygen -Overify-time=INVALID -Y check-novalidate -s doesnotmatter 2>&1 | grep -q -F "Invalid \"verify-time\"" &&
+
+	# Set up keys with key lifetimes
 	ssh-keygen -t ed25519 -N "" -C "timeboxed valid key" -f "${GPGSSH_KEY_TIMEBOXEDVALID}" >/dev/null &&
-	echo "\"timeboxed valid key\" valid-after=\"20050407000000\",valid-before=\"200504100000\" $(cat "${GPGSSH_KEY_TIMEBOXEDVALID}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
+	key_valid=$(cat "${GPGSSH_KEY_TIMEBOXEDVALID}.pub") &&
 	ssh-keygen -t ed25519 -N "" -C "timeboxed invalid key" -f "${GPGSSH_KEY_TIMEBOXEDINVALID}" >/dev/null &&
-	echo "\"timeboxed invalid key\" valid-after=\"20050401000000\",valid-before=\"20050402000000\" $(cat "${GPGSSH_KEY_TIMEBOXEDINVALID}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
+	key_invalid=$(cat "${GPGSSH_KEY_TIMEBOXEDINVALID}.pub") &&
 	ssh-keygen -t ed25519 -N "" -C "expired key" -f "${GPGSSH_KEY_EXPIRED}" >/dev/null &&
-	echo "\"principal with expired key\" valid-before=\"20000101000000\" $(cat "${GPGSSH_KEY_EXPIRED}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}" &&
+	key_expired=$(cat "${GPGSSH_KEY_EXPIRED}.pub") &&
 	ssh-keygen -t ed25519 -N "" -C "not yet valid key" -f "${GPGSSH_KEY_NOTYETVALID}" >/dev/null &&
-	echo "\"principal with not yet valid key\" valid-after=\"29990101000000\" $(cat "${GPGSSH_KEY_NOTYETVALID}.pub")" >> "${GPGSSH_ALLOWED_SIGNERS}"
+	key_notyetvalid=$(cat "${GPGSSH_KEY_NOTYETVALID}.pub") &&
+
+	# Timestamps outside of test_tick span
+	ts2005a=20050401000000 ts2005b=200504020000 &&
+	# Timestamps within test_tick span
+	ts2005c=20050407000000 ts2005d=200504100000 &&
+	# Definitely not yet valid / expired timestamps
+	ts2000=20000101000000 ts2999=29990101000000 &&
+
+	cat >>"${GPGSSH_ALLOWED_SIGNERS}" <<-EOF &&
+	"timeboxed valid key" valid-after="$ts2005c",valid-before="$ts2005d" $key_valid"
+	"timeboxed invalid key" valid-after="$ts2005a",valid-before="$ts2005b" $key_invalid"
+	"principal with expired key" valid-before="$ts2000" $key_expired"
+	"principal with not yet valid key" valid-after="$ts2999" $key_notyetvalid"
+	EOF
+
+	# and verify ssh-keygen verifies the key lifetime
+	echo "testpayload" |
+	ssh-keygen -Y sign -n "git" -f "${GPGSSH_KEY_EXPIRED}" >gpgssh_verifytime_prereq.sig &&
+	! (ssh-keygen -Y verify -n "git" -f "${GPGSSH_ALLOWED_SIGNERS}" -I "principal with expired key" -s gpgssh_verifytime_prereq.sig)
 '
 
 sanitize_pgp() {