ok beck@, with an appropriate commit message
On Mon, Jul 04, 2016 at 06:59:28PM -0500, Brent Cook wrote:
> I copied some of the commit text here from BoringSSL, but it's wrong for
> LibreSSL it seems.
>
> BN_ULLONG is not defined on all 64-bit systems as far as I can tell. So, this
> fix is more widely applicable than Win64 for LibreSSL.
>
> Any comments?
>
> - Brent
>
> > On Jun 30, 2016, at 8:40 AM, Brent Cook <bust...@gmail.com> wrote:
> >
> > On systems where we do not have BN_ULLONG (notably Win64), BN_mod_word()
> > can return incorrect results if the supplied modulus is too big.
> >
> > Note now that BN_mod_word may fail, like BN_div_word. Handle this
> > properly and document in the man page.
> >
> > Thanks to Brian Smith for pointing out these fixes from BoringSSL:
> >
> > https://boringssl.googlesource.com/boringssl/+/67cb49d045f04973ddba0f92fe8a8ad483c7da89
> > https://boringssl.googlesource.com/boringssl/+/44bedc348d9491e63c7ed1438db100a4b8a830be
> >
> > diff --git a/src/lib/libcrypto/man/BN_add_word.3
> > b/src/lib/libcrypto/man/BN_add_word.3
> > index eb5874a..66fdc0a 100644
> > --- a/src/lib/libcrypto/man/BN_add_word.3
> > +++ b/src/lib/libcrypto/man/BN_add_word.3
> > @@ -75,7 +75,8 @@ returns the remainder of
> > .Fa a
> > divided by
> > .Fa w
> > -.Pq Li a%w .
> > +.Pq Li a%w
> > +or (BN_ULONG)-1 on error.
> > .Pp
> > For
> > .Fn BN_div_word
> > diff --git a/src/lib/libssl/src/crypto/bn/bn_prime.c
> > b/src/lib/libssl/src/crypto/bn/bn_prime.c
> > index 09af6a1..1dd0153 100644
> > --- a/src/lib/libssl/src/crypto/bn/bn_prime.c
> > +++ b/src/lib/libssl/src/crypto/bn/bn_prime.c
> > @@ -277,9 +277,13 @@ BN_is_prime_fasttest_ex(const BIGNUM *a, int checks,
> > BN_CTX *ctx_passed,
> > /* a is even => a is prime if and only if a == 2 */
> > return BN_is_word(a, 2);
> > if (do_trial_division) {
> > - for (i = 1; i < NUMPRIMES; i++)
> > - if (BN_mod_word(a, primes[i]) == 0)
> > + for (i = 1; i < NUMPRIMES; i++) {
> > + BN_ULONG mod = BN_mod_word(a, primes[i]);
> > + if (mod == (BN_ULONG)-1)
> > + goto err;
> > + if (mod == 0)
> > return 0;
> > + }
> > if (!BN_GENCB_call(cb, 1, -1))
> > goto err;
> > }
> > @@ -398,8 +402,12 @@ again:
> > if (!BN_rand(rnd, bits, 1, 1))
> > return (0);
> > /* we now have a random number 'rand' to test. */
> > - for (i = 1; i < NUMPRIMES; i++)
> > - mods[i] = (prime_t)BN_mod_word(rnd, (BN_ULONG)primes[i]);
> > + for (i = 1; i < NUMPRIMES; i++) {
> > + BN_ULONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]);
> > + if (mod == (BN_ULONG)-1)
> > + return (0);
> > + mods[i] = (prime_t)mod;
> > + }
> > maxdelta = BN_MASK2 - primes[NUMPRIMES - 1];
> > delta = 0;
> > loop:
> > @@ -452,7 +460,10 @@ probable_prime_dh(BIGNUM *rnd, int bits, const BIGNUM
> > *add, const BIGNUM *rem,
> > loop:
> > for (i = 1; i < NUMPRIMES; i++) {
> > /* check that rnd is a prime */
> > - if (BN_mod_word(rnd, (BN_ULONG)primes[i]) <= 1) {
> > + BN_LONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]);
> > + if (mod == (BN_ULONG)-1)
> > + goto err;
> > + if (mod <= 1) {
> > if (!BN_add(rnd, rnd, add))
> > goto err;
> > goto loop;
> > @@ -514,8 +525,11 @@ loop:
> > /* check that p and q are prime */
> > /* check that for p and q
> > * gcd(p-1,primes) == 1 (except for 2) */
> > - if ((BN_mod_word(p, (BN_ULONG)primes[i]) == 0) ||
> > - (BN_mod_word(q, (BN_ULONG)primes[i]) == 0)) {
> > + BN_ULONG pmod = BN_mod_word(p, (BN_ULONG)primes[i]);
> > + BN_ULONG qmod = BN_mod_word(q, (BN_ULONG)primes[i]);
> > + if (pmod == (BN_ULONG)-1 || qmod == (BN_ULONG)-1)
> > + goto err;
> > + if (pmod == 0 || qmod == 0) {
> > if (!BN_add(p, p, padd))
> > goto err;
> > if (!BN_add(q, q, qadd))
> > diff --git a/src/lib/libssl/src/crypto/bn/bn_word.c
> > b/src/lib/libssl/src/crypto/bn/bn_word.c
> > index 897b06d..acc7032 100644
> > --- a/src/lib/libssl/src/crypto/bn/bn_word.c
> > +++ b/src/lib/libssl/src/crypto/bn/bn_word.c
> > @@ -73,6 +73,20 @@ BN_mod_word(const BIGNUM *a, BN_ULONG w)
> > if (w == 0)
> > return (BN_ULONG) - 1;
> >
> > +#ifndef BN_ULLONG
> > + /* If |w| is too long and we don't have |BN_ULLONG| then we need to
> > fall back
> > + * to using |BN_div_word|. */
> > + if (w > ((BN_ULONG)1 << BN_BITS4)) {
> > + BIGNUM *tmp = BN_dup(a);
> > + if (tmp == NULL) {
> > + return (BN_ULONG)-1;
> > + }
> > + ret = BN_div_word(tmp, w);
> > + BN_free(tmp);
> > + return ret;
> > + }
> > +#endif
> > +
> > bn_check_top(a);
> > w &= BN_MASK2;
> > for (i = a->top - 1; i >= 0; i--) {
> > diff --git a/src/lib/libssl/src/crypto/dh/dh_check.c
> > b/src/lib/libssl/src/crypto/dh/dh_check.c
> > index ad827dd..c34511d 100644
> > --- a/src/lib/libssl/src/crypto/dh/dh_check.c
> > +++ b/src/lib/libssl/src/crypto/dh/dh_check.c
> > @@ -89,10 +89,14 @@ DH_check(const DH *dh, int *ret)
> >
> > if (BN_is_word(dh->g, DH_GENERATOR_2)) {
> > l = BN_mod_word(dh->p, 24);
> > + if (l == (BN_ULONG)-1)
> > + goto err;
> > if (l != 11)
> > *ret |= DH_NOT_SUITABLE_GENERATOR;
> > } else if (BN_is_word(dh->g, DH_GENERATOR_5)) {
> > l = BN_mod_word(dh->p, 10);
> > + if (l == (BN_ULONG)-1)
> > + goto err;
> > if (l != 3 && l != 7)
> > *ret |= DH_NOT_SUITABLE_GENERATOR;
> > } else
> > diff --git a/src/regress/lib/libcrypto/bn/general/bntest.c
> > b/src/regress/lib/libcrypto/bn/general/bntest.c
> > index c6bd788..1d54177 100644
> > --- a/src/regress/lib/libcrypto/bn/general/bntest.c
> > +++ b/src/regress/lib/libcrypto/bn/general/bntest.c
> > @@ -514,7 +514,7 @@ int
> > test_div_word(BIO *bp)
> > {
> > BIGNUM a, b;
> > - BN_ULONG r, s;
> > + BN_ULONG r, rmod, s;
> > int i;
> > int rc = 1;
> >
> > @@ -523,14 +523,34 @@ test_div_word(BIO *bp)
> >
> > for (i = 0; i < num0; i++) {
> > do {
> > - BN_bntest_rand(&a, 512, -1, 0);
> > - BN_bntest_rand(&b, BN_BITS2, -1, 0);
> > + if (!BN_bntest_rand(&a, 512, -1, 0) ||
> > + !BN_bntest_rand(&b, BN_BITS2, -1, 0)) {
> > + rc = 0;
> > + break;
> > + }
> > s = b.d[0];
> > } while (!s);
> >
> > - BN_copy(&b, &a);
> > + if (!BN_copy(&b, &a)) {
> > + rc = 0;
> > + break;
> > + }
> > +
> > + s = b.d[0];
> > + rmod = BN_mod_word(&b, s);
> > r = BN_div_word(&b, s);
> >
> > + if (r == (BN_ULONG)-1 || rmod == (BN_ULONG)-1) {
> > + rc = 0;
> > + break;
> > + }
> > +
> > + if (rmod != r) {
> > + fprintf(stderr, "Mod (word) test failed!\n");
> > + rc = 0;
> > + break;
> > + }
> > +
> > if (bp != NULL) {
> > if (!results) {
> > BN_print(bp, &a);
>
