Fuzzer harnesses for sig verify and pubkey parsing

These are some basic clang libfuzzer harnesses for signature
verification and public key parsing. Some assembly (metaphorical)
required.

1 files changed, 50 insertions, 0 deletions

diff --git a/regress/misc/fuzz-harness/sig_fuzz.cc b/regress/misc/fuzz-harness/sig_fuzz.cc
new file mode 100644
index 000000000..0e535b49a
--- /dev/null
+++ b/regress/misc/fuzz-harness/sig_fuzz.cc
@@ -0,0 +1,50 @@
+// cc_fuzz_target test for public key parsing.
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+extern "C" {
+
+#include "includes.h"
+#include "sshkey.h"
+#include "ssherr.h"
+
+static struct sshkey *generate_or_die(int type, unsigned bits) {
+  int r;
+  struct sshkey *ret;
+  if ((r = sshkey_generate(type, bits, &ret)) != 0) {
+    fprintf(stderr, "generate(%d, %u): %s", type, bits, ssh_err(r));
+    abort();
+  }
+  return ret;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t* sig, size_t slen)
+{
+#ifdef WITH_OPENSSL
+  static struct sshkey *rsa = generate_or_die(KEY_RSA, 2048);
+  static struct sshkey *dsa = generate_or_die(KEY_DSA, 1024);
+  static struct sshkey *ecdsa256 = generate_or_die(KEY_ECDSA, 256);
+  static struct sshkey *ecdsa384 = generate_or_die(KEY_ECDSA, 384);
+  static struct sshkey *ecdsa521 = generate_or_die(KEY_ECDSA, 521);
+#endif
+  static struct sshkey *ed25519 = generate_or_die(KEY_ED25519, 0);
+  static const char *data = "If everyone started announcing his nose had "
+      "run away, I don’t know how it would all end";
+  static const size_t dlen = strlen(data);
+
+#ifdef WITH_OPENSSL
+  sshkey_verify(rsa, sig, slen, (const u_char *)data, dlen, 0);
+  sshkey_verify(dsa, sig, slen, (const u_char *)data, dlen, 0);
+  sshkey_verify(ecdsa256, sig, slen, (const u_char *)data, dlen, 0);
+  sshkey_verify(ecdsa384, sig, slen, (const u_char *)data, dlen, 0);
+  sshkey_verify(ecdsa521, sig, slen, (const u_char *)data, dlen, 0);
+#endif
+  sshkey_verify(ed25519, sig, slen, (const u_char *)data, dlen, 0);
+  return 0;
+}
+
+} // extern