1 files changed, 110 insertions, 0 deletions
diff --git a/lib/fuzzing/fuzz_sddl_parse.c b/lib/fuzzing/fuzz_sddl_parse.c
new file mode 100644
index 0000000..05900b0
--- /dev/null
+++ b/lib/fuzzing/fuzz_sddl_parse.c
@@ -0,0 +1,110 @@
+/*
+  Fuzz sddl decoding and encoding
+  Copyright (C) Catalyst IT 2023
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "libcli/security/security.h"
+#include "librpc/gen_ndr/conditional_ace.h"
+#include "fuzzing/fuzzing.h"
+#include "util/charset/charset.h"
+
+#define MAX_LENGTH (100 * 1024 - 1)
+static char sddl_string[MAX_LENGTH + 1] = {0};
+static struct dom_sid dom_sid = {0};
+
+int LLVMFuzzerInitialize(int *argc, char ***argv)
+{
+	string_to_sid(&dom_sid,
+		      "S-1-5-21-2470180966-3899876309-2637894779");
+	return 0;
+}
+
+
+int LLVMFuzzerTestOneInput(const uint8_t *input, size_t len)
+{
+	TALLOC_CTX *mem_ctx = NULL;
+	struct security_descriptor *sd1 = NULL;
+	struct security_descriptor *sd2 = NULL;
+	char *result = NULL;
+	bool ok;
+
+	if (len > MAX_LENGTH) {
+		return 0;
+	}
+
+	memcpy(sddl_string, input, len);
+	sddl_string[len] = '\0';
+
+	mem_ctx = talloc_new(NULL);
+
+	sd1 = sddl_decode(mem_ctx, sddl_string, &dom_sid);
+	if (sd1 == NULL) {
+		goto end;
+	}
+	result = sddl_encode(mem_ctx, sd1, &dom_sid);
+	if (result == NULL) {
+		/*
+		 * Because Samba currently doesn't enforce strict
+		 * utf-8 parsing, illegal utf-8 sequences in
+		 * sddl_string could have ferried bad characters
+		 * through into the security descriptor conditions
+		 * that we then find we can't encode.
+		 *
+		 * The proper solution is strict UTF-8 enforcement in
+		 * sddl_decode, but for now we forgive unencodable
+		 * security descriptors made from bad utf-8.
+		 */
+		size_t byte_len, char_len, utf16_len;
+		ok = utf8_check(sddl_string, len,
+				&byte_len, &char_len, &utf16_len);
+		if (!ok) {
+			goto end;
+		}
+		/* utf-8 was fine, but we couldn't encode! */
+		abort();
+	}
+
+	sd2 = sddl_decode(mem_ctx, result, &dom_sid);
+	if (sd2 == NULL) {
+		if (strlen(result) > CONDITIONAL_ACE_MAX_LENGTH) {
+			/*
+			 * This could fail if a unicode string or
+			 * attribute name that contains escapable
+			 * bytes (e.g '\x0b') in an unescaped form in
+			 * the original string ends up with them in
+			 * the escaped form ("%000b") in the result
+			 * string, making the entire attribute name
+			 * too long for the arbitrary limit we set for
+			 * SDDL attribute names.
+			 *
+			 * We could increase that arbitrary limit (to,
+			 * say, CONDITIONAL_ACE_MAX_LENGTH * 5), but
+			 * that is getting very far from real world
+			 * needs.
+			 */
+			goto end;
+		}
+		abort();
+	}
+	ok = security_descriptor_equal(sd1, sd2);
+	if (!ok) {
+		abort();
+	}
+end:
+	talloc_free(mem_ctx);
+	return 0;
+}