Fix: Isolate installer GPG inspection

setup/lib/artifact-provenance

@@ -6,10 +6,16 @@
 
 declare -gA INSTALLER_PROVENANCE=()
 
-_primary_key_fingerprints() {
+_primary_key_fingerprints() (
-    gpg --batch --with-colons --import-options show-only --import "$1" 2>/dev/null \
+    local home
+    home="$(mktemp -d)" || exit 1
+    chmod 700 "$home"
+    trap 'rm -rf -- "$home"' EXIT
+    trap 'exit 130' INT
+    trap 'exit 143' TERM
+    GNUPGHOME="$home" gpg --batch --with-colons --import-options show-only --import "$1" 2>/dev/null \
         | awk -F: '$1 == "pub" { primary = 1; next } primary && $1 == "fpr" { print $10; primary = 0 }'
-}
+)
 
 key_fingerprint_matches() {
     local file="$1" expected="$2"
@@ -27,13 +33,15 @@ _key_has_one_primary() {
 verify_detached_signature() {
     local key="$1" signature="$2" content="$3" home
     _key_has_one_primary "$key" || return 1
-    home="$(mktemp -d)" || return 1
+    (
-    chmod 700 "$home"
+        home="$(mktemp -d)" || exit 1
-    GNUPGHOME="$home" gpg --batch --quiet --import "$key" >/dev/null 2>&1 \
+        chmod 700 "$home"
-        && GNUPGHOME="$home" gpg --batch --verify "$signature" "$content" >/dev/null 2>&1
+        trap 'rm -rf -- "$home"' EXIT
-    local status=$?
+        trap 'exit 130' INT
-    rm -rf -- "$home"
+        trap 'exit 143' TERM
-    return "$status"
+        GNUPGHOME="$home" gpg --batch --quiet --import "$key" >/dev/null 2>&1 \
+            && GNUPGHOME="$home" gpg --batch --verify "$signature" "$content" >/dev/null 2>&1
+    )
 }
 
 download_sha256() {

tests/setup/package-provenance-contract

@@ -10,6 +10,7 @@ config="$repo_dir/setup/provenance/installers.conf"
 test_tmp="$(mktemp -d)"
 host_gnupg="${GNUPGHOME:-$HOME/.gnupg}"
 host_rpmdb="/usr/lib/sysimage/rpm/rpmdb.sqlite"
+ambient_gnupg="$test_tmp/fresh-ambient-gnupg"
 
 cleanup() {
     rm -rf -- "$test_tmp"
@@ -55,6 +56,14 @@ snapshot_gpg_state() {
     done < <(find "$path" -maxdepth 1 -type f \( -name pubring.kbx -o -name trustdb.gpg \) | sort)
 }
 
+export GNUPGHOME="$ambient_gnupg"
+mkdir -m 700 "$ambient_gnupg"
+ambient_before="$(snapshot "$ambient_gnupg")"
+ambient_gpg_files_before="$(snapshot_gpg_state "$ambient_gnupg")"
+before_gnupg="$(snapshot "$host_gnupg")"
+before_gpg_files="$(snapshot_gpg_state "$host_gnupg")"
+before_rpmdb="$(snapshot "$host_rpmdb")"
+
 # This must be the only production file sourced by the contract.
 # shellcheck source=../../setup/lib/artifact-provenance
 source "$repo_dir/setup/lib/artifact-provenance"
@@ -70,6 +79,10 @@ base64 --decode "$fixtures/wrong-signer-fixture.rpm.base64" > "$test_tmp/wrong-s
     || fail 'tampered artifact does not differ by exactly one byte'
 
 expect_success key_fingerprint_matches "$fixtures/fixture-key.asc" "$fixture_fingerprint"
+[[ "$ambient_before" == "$(snapshot "$ambient_gnupg")" ]] \
+    || fail 'fingerprint inspection created ambient GPG state'
+[[ "$ambient_gpg_files_before" == "$(snapshot_gpg_state "$ambient_gnupg")" ]] \
+    || fail 'fingerprint inspection created an ambient GPG keybox or trust database'
 expect_failure key_fingerprint_matches "$fixtures/fixture-key.asc" '0000000000000000000000000000000000000000'
 cat "$fixtures/fixture-key.asc" "$fixtures/wrong-signer-key.asc" > "$test_tmp/combined-key.asc"
 expect_failure key_fingerprint_matches "$test_tmp/combined-key.asc" "$fixture_fingerprint"
@@ -78,6 +91,8 @@ expect_success verify_detached_signature \
     "$fixtures/fixture-key.asc" "$fixtures/SHASUMS256.txt.asc" "$fixtures/SHASUMS256.txt"
 expect_failure verify_detached_signature \
     "$fixtures/fixture-key.asc" "$fixtures/SHASUMS256.txt.asc" "$fixtures/tiny-artifact"
+expect_failure verify_detached_signature \
+    "$fixtures/fixture-key.asc" "$fixtures/SHASUMS256.txt.asc" "$fixtures/tiny-artifact-tampered"
 cp "$fixtures/SHASUMS256.txt.asc" "$test_tmp/bad-signature.asc"
 sed -i 's/^=MJqv$/=MJqa/' "$test_tmp/bad-signature.asc"
 expect_failure verify_detached_signature \
@@ -159,9 +174,6 @@ expect_failure download_sha256 'https://fixture.invalid/interrupted' "$tiny_sha2
 assert_file_bytes "$destination" 'known-good'
 [[ ! -e "$destination.part" ]] || fail 'interrupted download left a part file'
 
-before_gnupg="$(snapshot "$host_gnupg")"
-before_gpg_files="$(snapshot_gpg_state "$host_gnupg")"
-before_rpmdb="$(snapshot "$host_rpmdb")"
 expect_success rpm_signature_matches \
     "$test_tmp/signed-fixture.rpm" "$fixtures/fixture-key.asc" "$fixture_fingerprint"
 expect_failure rpm_signature_matches \
@@ -175,6 +187,9 @@ expect_failure rpm_signature_matches \
 [[ "$before_gnupg" == "$(snapshot "$host_gnupg")" ]] || fail 'host GPG state changed'
 [[ "$before_gpg_files" == "$(snapshot_gpg_state "$host_gnupg")" ]] || fail 'host GPG keybox or trust database changed'
 [[ "$before_rpmdb" == "$(snapshot "$host_rpmdb")" ]] || fail 'host RPM database changed'
+[[ "$ambient_before" == "$(snapshot "$ambient_gnupg")" ]] || fail 'production helper created ambient GPG state'
+[[ "$ambient_gpg_files_before" == "$(snapshot_gpg_state "$ambient_gnupg")" ]] \
+    || fail 'production helper created an ambient GPG keybox or trust database'
 
 expect_success load_installer_provenance "$config"
 [[ "${INSTALLER_PROVENANCE[BUN_VERSION]:-}" == '1.4.0' ]] || fail 'valid provenance was not loaded'