115 lines
4.3 KiB
Diff
115 lines
4.3 KiB
Diff
From 839b89f45a38b2373bf5836337a33f450aaab72e Mon Sep 17 00:00:00 2001
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From: Richard Hughes <richard@hughsie.com>
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Date: Thu, 28 May 2020 10:41:23 +0100
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Subject: [PATCH] Validate that gpgme_op_verify_result() returned at least one
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signature
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If a detached signature is actually a PGP message, gpgme_op_verify() returns
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the rather perplexing GPG_ERR_NO_ERROR, and then gpgme_op_verify_result()
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builds an empty list.
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Explicitly check for no signatures present to avoid returning a JcatResult with
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no timestamp and an empty authority.
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Many thanks to Justin Steven <justin@justinsteven.com> for the discovery and
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coordinated disclosure of this issue. Fixes CVE-2020-10759
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---
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libjcat/jcat-gpg-engine.c | 7 +++++
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libjcat/jcat-self-test.c | 55 +++++++++++++++++++++++++++++++++++++++
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2 files changed, 62 insertions(+)
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diff --git libjcat/jcat-gpg-engine.c libjcat/jcat-gpg-engine.c
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index 0812a62..bd44dba 100644
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--- libjcat/jcat-gpg-engine.c
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+++ libjcat/jcat-gpg-engine.c
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@@ -267,6 +267,13 @@ jcat_gpg_engine_pubkey_verify (JcatEngine *engine,
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"no result record from libgpgme");
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return NULL;
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}
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+ if (result->signatures == NULL) {
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+ g_set_error_literal (error,
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+ G_IO_ERROR,
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+ G_IO_ERROR_FAILED,
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+ "no signatures from libgpgme");
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+ return NULL;
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+ }
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/* look at each signature */
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for (s = result->signatures; s != NULL ; s = s->next ) {
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diff --git libjcat/jcat-self-test.c libjcat/jcat-self-test.c
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index d79a3a9..fd4295e 100644
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--- libjcat/jcat-self-test.c
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+++ libjcat/jcat-self-test.c
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@@ -393,6 +393,60 @@ jcat_gpg_engine_func (void)
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#endif
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}
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+static void
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+jcat_gpg_engine_msg_func (void)
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+{
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+#ifdef ENABLE_GPG
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+ g_autofree gchar *fn = NULL;
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+ g_autofree gchar *pki_dir = NULL;
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+ g_autoptr(GBytes) data = NULL;
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+ g_autoptr(GBytes) data_sig = NULL;
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+ g_autoptr(GError) error = NULL;
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+ g_autoptr(JcatContext) context = jcat_context_new ();
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+ g_autoptr(JcatEngine) engine = NULL;
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+ g_autoptr(JcatResult) result = NULL;
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+ const gchar *sig =
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+ "-----BEGIN PGP MESSAGE-----\n"
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+ "owGbwMvMwMEovmZX76/pfOKMp0WSGOLOX3/ikZqTk6+jUJ5flJOiyNXJaMzCwMjB\n"
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+ "ICumyCJmt5VRUil28/1+z1cwbaxMID0MXJwCMJG4RxwMLUYXDkUad34I3vrT8+X2\n"
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+ "m+ZyHyMWnTiQYaQb/eLJGqbiAJc5Jr4a/PPqHNi7auwzGsKsljebabjtnJRzpDr0\n"
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+ "YvwrnmmWLJUnTzjM3MH5Kn+RzqXkywsYdk9yD2OUdLy736CiemFMdcuF02lOZvPU\n"
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+ "HaTKl76wW62QH8Lr8yGMQ1Xgc6nC2ZwUhvctky7NOZtc1T477uBTL81p31ZmaIUJ\n"
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+ "paS8uWZl8UzX5sFsqQi37G1TbDc8Cm+oU/yRkFj2pLBzw367ncsa4n7EqEWu1yrN\n"
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+ "yD39LUeErePdqfKCG+xhL6WkWt5ZJ/6//XnjouXhl5Z4tWspT49MtNp5d3aDQ43c\n"
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+ "mnbresn6A7KMZgdOiwIA\n"
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+ "=a9ui\n"
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+ "-----END PGP MESSAGE-----\n";
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+
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+ /* set up context */
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+ jcat_context_set_keyring_path (context, "/tmp/libjcat-self-test/var");
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+ pki_dir = g_test_build_filename (G_TEST_DIST, "pki", NULL);
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+ jcat_context_add_public_keys (context, pki_dir);
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+
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+ /* get engine */
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+ engine = jcat_context_get_engine (context, JCAT_BLOB_KIND_GPG, &error);
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+ g_assert_no_error (error);
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+ g_assert_nonnull (engine);
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+ g_assert_cmpint (jcat_engine_get_kind (engine), ==, JCAT_BLOB_KIND_GPG);
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+ g_assert_cmpint (jcat_engine_get_verify_kind (engine), ==, JCAT_ENGINE_VERIFY_KIND_SIGNATURE);
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+
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+ /* verify with GnuPG, which should fail as the signature is not a
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+ * detached signature at all, but gnupg stabs us in the back by returning
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+ * success from gpgme_op_verify() with an empty list of signatures */
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+ fn = g_test_build_filename (G_TEST_DIST, "colorhug", "firmware.bin", NULL);
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+ data = jcat_get_contents_bytes (fn, &error);
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+ g_assert_no_error (error);
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+ g_assert_nonnull (data);
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+ data_sig = g_bytes_new_static (sig, strlen (sig));
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+ result = jcat_engine_pubkey_verify (engine, data, data_sig,
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+ JCAT_VERIFY_FLAG_NONE, &error);
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+ g_assert_error (error, G_IO_ERROR, G_IO_ERROR_FAILED);
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+ g_assert_null (result);
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+#else
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+ g_test_skip ("no GnuPG support enabled");
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+#endif
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+}
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+
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static void
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jcat_pkcs7_engine_func (void)
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{
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@@ -753,6 +807,7 @@ main (int argc, char **argv)
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g_test_add_func ("/jcat/engine{sha1}", jcat_sha1_engine_func);
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g_test_add_func ("/jcat/engine{sha256}", jcat_sha256_engine_func);
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g_test_add_func ("/jcat/engine{gpg}", jcat_gpg_engine_func);
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+ g_test_add_func ("/jcat/engine{gpg-msg}", jcat_gpg_engine_msg_func);
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g_test_add_func ("/jcat/engine{pkcs7}", jcat_pkcs7_engine_func);
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g_test_add_func ("/jcat/engine{pkcs7-self-signed}", jcat_pkcs7_engine_self_signed_func);
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g_test_add_func ("/jcat/context{verify-blob}", jcat_context_verify_blob_func);
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--
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2.26.2
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