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, 5 insertions, 11 deletions

diff --git a/crypto/pbkdf.c b/crypto/pbkdf.c
index 695cc35..929458b 100644
--- a/crypto/pbkdf.c
+++ b/crypto/pbkdf.c
@@ -62,13 +62,13 @@ static int qcrypto_pbkdf2_get_thread_cpu(unsigned long long *val_ms,
 #endif
 }
 
-int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
-                               const uint8_t *key, size_t nkey,
-                               const uint8_t *salt, size_t nsalt,
-                               Error **errp)
+uint64_t qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
+                                    const uint8_t *key, size_t nkey,
+                                    const uint8_t *salt, size_t nsalt,
+                                    Error **errp)
 {
     uint8_t out[32];
-    long long int iterations = (1 << 15);
+    uint64_t iterations = (1 << 15);
     unsigned long long delta_ms, start_ms, end_ms;
 
     while (1) {
@@ -100,11 +100,5 @@ int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
 
     iterations = iterations * 1000 / delta_ms;
 
-    if (iterations > INT32_MAX) {
-        error_setg(errp, "Iterations %lld too large for a 32-bit int",
-                   iterations);
-        return -1;
-    }
-
     return iterations;
 }