crypto: use uint64_t for pbkdf iteration count parameters

The qcrypto_pbkdf_count_iters method uses a 64 bit int
but then checks its value against INT32_MAX before
returning it. This bounds check is premature, because
the calling code may well scale the iteration count
by some value. It is thus better to return a 64-bit
integer and let the caller do range checking.

For consistency the qcrypto_pbkdf method is also changed
to accept a 64bit int, though this is somewhat academic
since nettle is limited to taking an 'int' while gcrypt
is limited to taking a 'long int'.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/crypto/pbkdf-nettle.c b/crypto/pbkdf-nettle.c
index d681a60..db81517 100644
--- a/crypto/pbkdf-nettle.c
+++ b/crypto/pbkdf-nettle.c
@@ -38,10 +38,16 @@ bool qcrypto_pbkdf2_supports(QCryptoHashAlgorithm hash)
 int qcrypto_pbkdf2(QCryptoHashAlgorithm hash,
                    const uint8_t *key, size_t nkey,
                    const uint8_t *salt, size_t nsalt,
-                   unsigned int iterations,
+                   uint64_t iterations,
                    uint8_t *out, size_t nout,
                    Error **errp)
 {
+    if (iterations > UINT_MAX) {
+        error_setg_errno(errp, ERANGE,
+                         "PBKDF iterations %llu must be less than %u",
+                         (long long unsigned)iterations, UINT_MAX);
+        return -1;
+    }
     switch (hash) {
     case QCRYPTO_HASH_ALG_SHA1:
         pbkdf2_hmac_sha1(nkey, key,