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[Qemu-devel] [PULL v1 3/8] crypto: clear out buffer after timing pbkdf a
From: |
Daniel P. Berrange |
Subject: |
[Qemu-devel] [PULL v1 3/8] crypto: clear out buffer after timing pbkdf algorithm |
Date: |
Mon, 19 Sep 2016 12:44:07 +0100 |
The 'out' buffer will hold a key derived from master
password, so it is best practice to clear this buffer
when no longer required.
At this time, the code isn't worrying about locking
buffers into RAM to prevent swapping sensitive data
to disk.
Reviewed-by: Eric Blake <address@hidden>
Signed-off-by: Daniel P. Berrange <address@hidden>
---
crypto/pbkdf.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/crypto/pbkdf.c b/crypto/pbkdf.c
index 929458b..e391505 100644
--- a/crypto/pbkdf.c
+++ b/crypto/pbkdf.c
@@ -67,13 +67,14 @@ uint64_t qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm
hash,
const uint8_t *salt, size_t nsalt,
Error **errp)
{
+ uint64_t ret = -1;
uint8_t out[32];
uint64_t iterations = (1 << 15);
unsigned long long delta_ms, start_ms, end_ms;
while (1) {
if (qcrypto_pbkdf2_get_thread_cpu(&start_ms, errp) < 0) {
- return -1;
+ goto cleanup;
}
if (qcrypto_pbkdf2(hash,
key, nkey,
@@ -81,10 +82,10 @@ uint64_t qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm
hash,
iterations,
out, sizeof(out),
errp) < 0) {
- return -1;
+ goto cleanup;
}
if (qcrypto_pbkdf2_get_thread_cpu(&end_ms, errp) < 0) {
- return -1;
+ goto cleanup;
}
delta_ms = end_ms - start_ms;
@@ -100,5 +101,9 @@ uint64_t qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm
hash,
iterations = iterations * 1000 / delta_ms;
- return iterations;
+ ret = iterations;
+
+ cleanup:
+ memset(out, 0, sizeof(out));
+ return ret;
}
--
2.7.4
- [Qemu-devel] [PULL v1 0/8] Merge qcrypto 2016/09/19, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 2/8] crypto: make PBKDF iterations configurable for LUKS format, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 3/8] crypto: clear out buffer after timing pbkdf algorithm,
Daniel P. Berrange <=
- [Qemu-devel] [PULL v1 1/8] crypto: use uint64_t for pbkdf iteration count parameters, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 5/8] crypto: remove bogus /= 2 for pbkdf iterations, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 4/8] crypto: use correct derived key size when timing pbkdf, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 7/8] crypto: support more hash algorithms for pbkdf, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 8/8] crypto: add trace points for TLS cert verification, Daniel P. Berrange, 2016/09/19
- [Qemu-devel] [PULL v1 6/8] crypto: increase default pbkdf2 time for luks to 2 seconds, Daniel P. Berrange, 2016/09/19
- Re: [Qemu-devel] [PULL v1 0/8] Merge qcrypto 2016/09/19, no-reply, 2016/09/19