[PATCH 2/2] smime: tests of X.509 certificate validity are known-broken on GMime < 3.2.7

Daniel Kahn Gillmor dkg at fifthhorseman.net
Wed May 6 16:54:38 PDT 2020


When checking cryptographic signatures, Notmuch relies on GMime to
tell it whether the certificate that signs a message has a valid User
ID or not.

If the User ID is not valid, then notmuch does not report the signer's
User ID to the user.  This means that the consumer of notmuch's
cryptographic summary of a message (or of its protected headers) can
be confident in relaying the reported identity to the user.

However, some versions of GMime before 3.2.7 cannot report Certificate
validity for X.509 certificates.  This is resolved upstream in GMime
at https://github.com/jstedfast/gmime/pull/90.

We adapt to this by marking tests of reported User IDs for
S/MIME-signed messages as known-broken if GMime is older than 3.2.7
and has not been patched.

If GMime >= 3.2.7 and certificate validity still doesn't work for
X.509 certs, then there has likely been a regression in GMime and we
should fail early, during ./configure.

To break out these specific User ID checks from other checks, i had to
split some tests into two parts, and reuse $output across the two
subtests.

Signed-off-by: Daniel Kahn Gillmor <dkg at fifthhorseman.net>
---
 configure                      | 79 ++++++++++++++++++++++++++++++++++
 test/T355-smime.sh             | 19 +++++---
 test/T356-protected-headers.sh | 15 ++++++-
 3 files changed, 104 insertions(+), 9 deletions(-)

diff --git a/configure b/configure
index 0cfdaa6f..92e5bd1b 100755
--- a/configure
+++ b/configure
@@ -536,6 +536,82 @@ EOF
     if [ -n "$TEMP_GPG" -a -d "$TEMP_GPG" ]; then
         rm -rf "$TEMP_GPG"
     fi
+
+    # see https://github.com/jstedfast/gmime/pull/90
+    # should be fixed in GMime in 3.2.7, but some distros might patch
+    printf "Checking for GMime X.509 certificate validity... "
+
+    cat > _check_x509_validity.c <<EOF
+#include <stdio.h>
+#include <gmime/gmime.h>
+
+int main () {
+    GError *error = NULL;
+    GMimeParser *parser = NULL;
+    GMimeApplicationPkcs7Mime *body = NULL;
+    GMimeSignatureList *sig_list = NULL;
+    GMimeSignature *sig = NULL;
+    GMimeCertificate *cert = NULL;
+    GMimeObject *output = NULL;
+    GMimeValidity validity = GMIME_VALIDITY_UNKNOWN;
+    int len;
+
+    g_mime_init ();
+    parser = g_mime_parser_new ();
+    g_mime_parser_init_with_stream (parser, g_mime_stream_file_open("test/corpora/pkcs7/smime-onepart-signed.eml", "r", &error));
+    if (error) return !! fprintf (stderr, "failed to instantiate parser with test/corpora/pkcs7/smime-onepart-signed.eml\n");
+
+    body = GMIME_APPLICATION_PKCS7_MIME(g_mime_message_get_mime_part (g_mime_parser_construct_message (parser, NULL)));
+    if (body == NULL) return !!	fprintf (stderr, "did not find a application/pkcs7 message\n");
+
+    sig_list = g_mime_application_pkcs7_mime_verify (body, GMIME_VERIFY_NONE, &output, &error);
+    if (error || output == NULL) return !! fprintf (stderr, "verify failed\n");
+
+    if (sig_list == NULL) return !! fprintf (stderr, "no GMimeSignatureList found\n");
+    len = g_mime_signature_list_length (sig_list);
+    if (len != 1) return !! fprintf (stderr, "expected 1 signature, got %d\n", len);
+    sig = g_mime_signature_list_get_signature (sig_list, 0);
+    if (sig == NULL) return !! fprintf (stderr, "no GMimeSignature found at position 0\n");
+    cert = g_mime_signature_get_certificate (sig);
+    if (cert == NULL) return !! fprintf (stderr, "no GMimeCertificate found\n");
+    validity = g_mime_certificate_get_id_validity (cert);
+    if (validity != GMIME_VALIDITY_FULL) return !! fprintf (stderr, "Got validity %d, expected %d\n", validity, GMIME_VALIDITY_FULL);
+
+    return 0;
+}
+EOF
+    if ! TEMP_GPG=$(mktemp -d "${TMPDIR:-/tmp}/notmuch.XXXXXX"); then
+        printf 'No.\nCould not make tempdir for testing X.509 certificate validity support.\n'
+        errors=$((errors + 1))
+    elif ${CC} ${CFLAGS} ${gmime_cflags} _check_x509_validity.c ${gmime_ldflags} -o _check_x509_validity \
+            && echo disable-crl-checks > "$TEMP_GPG/gpgsm.conf" \
+            && echo "4D:E0:FF:63:C0:E9:EC:01:29:11:C8:7A:EE:DA:3A:9A:7F:6E:C1:0D S" >> "$TEMP_GPG/trustlist.txt" \
+            && GNUPGHOME=${TEMP_GPG} gpgsm --batch --quiet --import < "$srcdir"/test/smime/ca.crt
+    then
+        if GNUPGHOME=${TEMP_GPG} ./_check_x509_validity; then
+            gmime_x509_cert_validity=1
+            printf "Yes.\n"
+        else
+            gmime_x509_cert_validity=0
+            printf "No.\n"
+            if pkg-config --exists "gmime-3.0 >= 3.2.7"; then
+                cat <<EOF
+*** Error: GMime fails to calculate X.509 certificate validity, and
+is later than 3.2.7, which should have fixed this issue.
+
+Please follow up on https://github.com/jstedfast/gmime/pull/90 with
+more details.
+EOF
+                errors=$((errors + 1))
+            fi
+        fi
+    else
+        printf 'No.\nFailed to set up gpgsm for testing X.509 certificate validity support.\n'
+        errors=$((errors + 1))
+    fi
+    if [ -n "$TEMP_GPG" -a -d "$TEMP_GPG" ]; then
+        rm -rf "$TEMP_GPG"
+    fi
 else
     have_gmime=0
     printf "No.\n"
@@ -1334,6 +1410,9 @@ NOTMUCH_HAVE_XAPIAN_DB_RETRY_LOCK=${WITH_RETRY_LOCK}
 # Which backend will Xapian use by default?
 NOTMUCH_DEFAULT_XAPIAN_BACKEND=${default_xapian_backend}
 
+# Whether GMime can verify X.509 certificate validity
+NOTMUCH_GMIME_X509_CERT_VALIDITY=${gmime_x509_cert_validity}
+
 # do we have man pages?
 NOTMUCH_HAVE_MAN=$((have_sphinx))
 
diff --git a/test/T355-smime.sh b/test/T355-smime.sh
index 3573b5ee..170f8649 100755
--- a/test/T355-smime.sh
+++ b/test/T355-smime.sh
@@ -177,13 +177,18 @@ test_valid_json "$output"
 
 test_begin_subtest "Verify signature on PKCS#7 SignedData message"
 output=$(notmuch show --format=json id:smime-onepart-signed at protected-headers.example)
+
+test_json_nodes <<<"$output" \
+                'created:[0][0][0]["crypto"]["signed"]["status"][0]["created"]=1574813489' \
+                'expires:[0][0][0]["crypto"]["signed"]["status"][0]["expires"]=2611032858' \
+                'fingerprint:[0][0][0]["crypto"]["signed"]["status"][0]["fingerprint"]="702BA4B157F1E2B7D16B0C6A5FFC8A7DE2057DEB"' \
+                'status:[0][0][0]["crypto"]["signed"]["status"][0]["status"]="good"'
+
+test_begin_subtest "Verify signature on PKCS#7 SignedData message signer User ID"
+if [ $NOTMUCH_GMIME_X509_CERT_VALIDITY -ne 1 ]; then
+    test_subtest_known_broken
+fi
 test_json_nodes <<<"$output" \
-                'crypto:[0][0][0]["crypto"]["signed"]["status"][0]={
-                        "created" : 1574813489,
-                        "expires" : 2611032858,
-                        "fingerprint" : "702BA4B157F1E2B7D16B0C6A5FFC8A7DE2057DEB",
-                        "userid" : "CN=Alice Lovelace",
-                        "status" : "good"
-                     }'
+                'userid:[0][0][0]["crypto"]["signed"]["status"][0]["userid"]="CN=Alice Lovelace"'
 
 test_done
diff --git a/test/T356-protected-headers.sh b/test/T356-protected-headers.sh
index 547b0c9a..074a2345 100755
--- a/test/T356-protected-headers.sh
+++ b/test/T356-protected-headers.sh
@@ -162,8 +162,13 @@ for variant in multipart-signed onepart-signed; do
                     'signed_subject:[0][0][0]["crypto"]["signed"]["headers"]=["Subject"]' \
                     'sig_good:[0][0][0]["crypto"]["signed"]["status"][0]["status"]="good"' \
                     'sig_fpr:[0][0][0]["crypto"]["signed"]["status"][0]["fingerprint"]="702BA4B157F1E2B7D16B0C6A5FFC8A7DE2057DEB"' \
-                    'sig_uid:[0][0][0]["crypto"]["signed"]["status"][0]["userid"]="CN=Alice Lovelace"' \
                     'not_encrypted:[0][0][0]["crypto"]!"decrypted"'
+    test_begin_subtest "verify signed PKCS#7 subject ($variant) signer User ID"
+    if [ $NOTMUCH_GMIME_X509_CERT_VALIDITY -ne 1 ]; then
+        test_subtest_known_broken
+    fi
+    test_json_nodes <<<"$output" \
+                    'sig_uid:[0][0][0]["crypto"]["signed"]["status"][0]["userid"]="CN=Alice Lovelace"'
 done
 
 for variant in sign+enc sign+enc+legacy-disp; do
@@ -173,8 +178,14 @@ for variant in sign+enc sign+enc+legacy-disp; do
                     'signed_subject:[0][0][0]["crypto"]["signed"]["headers"]=["Subject"]' \
                     'sig_good:[0][0][0]["crypto"]["signed"]["status"][0]["status"]="good"' \
                     'sig_fpr:[0][0][0]["crypto"]["signed"]["status"][0]["fingerprint"]="702BA4B157F1E2B7D16B0C6A5FFC8A7DE2057DEB"' \
-                    'sig_uid:[0][0][0]["crypto"]["signed"]["status"][0]["userid"]="CN=Alice Lovelace"' \
                     'encrypted:[0][0][0]["crypto"]["decrypted"]={"status":"full","header-mask":{"Subject":"..."}}'
+    test_begin_subtest "confirm signed and encrypted PKCS#7 subject ($variant) signer User ID"
+    if [ $NOTMUCH_GMIME_X509_CERT_VALIDITY -ne 1 ]; then
+        test_subtest_known_broken
+    fi
+    test_json_nodes <<<"$output" \
+                    'sig_uid:[0][0][0]["crypto"]["signed"]["status"][0]["userid"]="CN=Alice Lovelace"'
+
 done
 
 test_begin_subtest "confirm encryption-protected PKCS#7 subject (enc+legacy-disp)"
-- 
2.26.2



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