Add test case checking aliasing of the result with other arguments

These are expected failures for BN_mod_exp_simple() and the internal
BN_mod_exp_recp(), which will be fixed shortly.

diff --git a/regress/lib/libcrypto/bn/Makefile b/regress/lib/libcrypto/bn/Makefile
index 8e4c74a..36149a7 100644 (file)
--- a/regress/lib/libcrypto/bn/Makefile
+++ b/regress/lib/libcrypto/bn/Makefile
@@ -1,4 +1,4 @@
-#      $OpenBSD: Makefile,v 1.35 2023/08/03 18:44:31 tb Exp $
+#      $OpenBSD: Makefile,v 1.36 2023/10/19 10:17:24 tb Exp $
 
 PROGS +=       bn_add_sub
 PROGS +=       bn_cmp
@@ -35,6 +35,8 @@ CFLAGS +=     -I${.CURDIR}/../../../../lib/libcrypto/bn/arch/${MACHINE_CPU}/
 # Use default targets from bsd.regress.mk unless overridden below
 REGRESS_TARGETS = ${PROGS:S/^/run-regress-/}
 
+REGRESS_EXPECTED_FAILURES = run-regress-bn_mod_exp
+
 # Verify that the bn_isqrt -C output isn't changed by accident.
 isqrt-print-tables: bn_isqrt
        @./bn_isqrt -C

diff --git a/regress/lib/libcrypto/bn/bn_mod_exp.c b/regress/lib/libcrypto/bn/bn_mod_exp.c
index 14e1883..6115738 100644 (file)
--- a/regress/lib/libcrypto/bn/bn_mod_exp.c
+++ b/regress/lib/libcrypto/bn/bn_mod_exp.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: bn_mod_exp.c,v 1.38 2023/05/09 05:39:24 tb Exp $ */
+/*     $OpenBSD: bn_mod_exp.c,v 1.39 2023/10/19 10:17:24 tb Exp $ */
 
 /*
  * Copyright (c) 2022,2023 Theo Buehler <tb@openbsd.org>
@@ -561,6 +561,109 @@ test_bn_mod_exp2_mont_crash(void)
        return failed;
 }
 
+static int
+test_mod_exp_aliased(const char *alias, int want_ret, BIGNUM *got,
+    const BIGNUM *want, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
+    BN_CTX *ctx, const struct mod_exp_test *test)
+{
+       int mod_exp_ret;
+       int ret = 0;
+
+       BN_CTX_start(ctx);
+
+       if (test->mod_exp_fn != NULL)
+               mod_exp_ret = test->mod_exp_fn(got, a, p, m, ctx);
+       else
+               mod_exp_ret = test->mod_exp_mont_fn(got, a, p, m, ctx, NULL);
+
+       if (mod_exp_ret != want_ret)
+               errx(1, "%s() %s aliased with result failed", test->name, alias);
+
+       if (!mod_exp_ret)
+               goto done;
+
+       if (BN_cmp(want, got) != 0) {
+               dump_results(a, p, NULL, NULL, m, want, got, test->name);
+               goto err;
+       }
+
+ done:
+       ret = 1;
+
+ err:
+       BN_CTX_end(ctx);
+
+       return ret;
+}
+
+static void
+test_bn_mod_exp_aliasing_setup(BIGNUM *want, BIGNUM *a, BIGNUM *p, BIGNUM *m,
+    BN_CTX *ctx)
+{
+       if (!BN_set_word(a, 1031))
+               errx(1, "BN_set_word");
+       if (!BN_set_word(p, 1033))
+               errx(1, "BN_set_word");
+       if (!BN_set_word(m, 1039))
+               errx(1, "BN_set_word");
+
+       if (!BN_mod_exp_simple(want, a, p, m, ctx))
+               errx(1, "BN_mod_exp");
+}
+
+static int
+test_bn_mod_exp_aliasing(void)
+{
+       BN_CTX *ctx;
+       BIGNUM *a, *p, *m, *want, *got;
+       size_t i;
+       int failed = 0;
+
+       if ((ctx = BN_CTX_new()) == NULL)
+               errx(1, "BN_CTX_new");
+
+       BN_CTX_start(ctx);
+
+       if ((a = BN_CTX_get(ctx)) == NULL)
+               errx(1, "a = BN_CTX_get()");
+       if ((p = BN_CTX_get(ctx)) == NULL)
+               errx(1, "p = BN_CTX_get()");
+       if ((m = BN_CTX_get(ctx)) == NULL)
+               errx(1, "m = BN_CTX_get()");
+       if ((want = BN_CTX_get(ctx)) == NULL)
+               errx(1, "want = BN_CTX_get()");
+       if ((got = BN_CTX_get(ctx)) == NULL)
+               errx(1, "got = BN_CTX_get()");
+
+       for (i = 0; i < N_MOD_EXP_FN; i++) {
+               const struct mod_exp_test *test = &mod_exp_fn[i];
+               int aliasing_allowed = 1;
+
+               test_bn_mod_exp_aliasing_setup(want, a, p, m, ctx);
+               if (!test_mod_exp_aliased("nothing", 1, got, want, a, p, m, ctx,
+                   test))
+                       failed |= 1;
+               test_bn_mod_exp_aliasing_setup(want, a, p, m, ctx);
+               if (!test_mod_exp_aliased("a", 1, a, want, a, p, m, ctx, test))
+                       failed |= 1;
+               test_bn_mod_exp_aliasing_setup(want, a, p, m, ctx);
+               if (!test_mod_exp_aliased("p", 1, p, want, a, p, m, ctx, test))
+                       failed |= 1;
+
+               if (test->mod_exp_fn == BN_mod_exp_simple)
+                       aliasing_allowed = 0;
+               test_bn_mod_exp_aliasing_setup(want, a, p, m, ctx);
+               if (!test_mod_exp_aliased("m", aliasing_allowed, m, want,
+                   a, p, m, ctx, test))
+                       failed |= 1;
+       }
+
+       BN_CTX_end(ctx);
+       BN_CTX_free(ctx);
+
+       return failed;
+}
+
 int
 main(void)
 {
@@ -570,6 +673,7 @@ main(void)
        failed |= test_bn_mod_exp();
        failed |= test_bn_mod_exp2();
        failed |= test_bn_mod_exp2_mont_crash();
+       failed |= test_bn_mod_exp_aliasing();
 
        return failed;
 }