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* [PATCH 2/3] crypto: ccp - return an actual key size from RSA max_size callback
@ 2018-02-24 16:03 ` Maciej S. Szmigiero
  0 siblings, 0 replies; 16+ messages in thread
From: Maciej S. Szmigiero @ 2018-02-24 16:03 UTC (permalink / raw)
  To: Herbert Xu, David S. Miller
  Cc: David Howells, Tom Lendacky, Gary Hook, keyrings, linux-crypto,
	linux-kernel

rsa-pkcs1pad uses a value returned from a RSA implementation max_size
callback as a size of an input buffer passed to the RSA implementation for
encrypt and sign operations.

CCP RSA implementation uses a hardware input buffer which size depends only
on the current RSA key length, so it should return this key length in
the max_size callback, too.
This also matches what the kernel software RSA implementation does.

Previously, the value returned from this callback was always the maximum
RSA key size the CCP hardware supports.
This resulted in this huge buffer being passed by rsa-pkcs1pad to CCP even
for smaller key sizes and then in a buffer overflow when ccp_run_rsa_cmd()
tried to copy this large input buffer into a RSA key length-sized hardware
input buffer.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Fixes: ceeec0afd684 ("crypto: ccp - Add support for RSA on the CCP")
Cc: stable@vger.kernel.org
---
 drivers/crypto/ccp/ccp-crypto-rsa.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/crypto/ccp/ccp-crypto-rsa.c b/drivers/crypto/ccp/ccp-crypto-rsa.c
index e6db8672d89c..05850dfd7940 100644
--- a/drivers/crypto/ccp/ccp-crypto-rsa.c
+++ b/drivers/crypto/ccp/ccp-crypto-rsa.c
@@ -60,10 +60,9 @@ static int ccp_rsa_complete(struct crypto_async_request *async_req, int ret)
 
 static unsigned int ccp_rsa_maxsize(struct crypto_akcipher *tfm)
 {
-	if (ccp_version() > CCP_VERSION(3, 0))
-		return CCP5_RSA_MAXMOD;
-	else
-		return CCP_RSA_MAXMOD;
+	struct ccp_ctx *ctx = akcipher_tfm_ctx(tfm);
+
+	return ctx->u.rsa.n_len;
 }
 
 static int ccp_rsa_crypt(struct akcipher_request *req, bool encrypt)

^ permalink raw reply related	[flat|nested] 16+ messages in thread

end of thread, other threads:[~2018-03-04 12:56 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-02-24 16:03 [PATCH 2/3] crypto: ccp - return an actual key size from RSA max_size callback Maciej S. Szmigiero
2018-02-24 16:03 ` Maciej S. Szmigiero
2018-03-01  0:34 ` Gary R Hook
2018-03-01  0:34   ` Gary R Hook
2018-03-02 16:44 ` Herbert Xu
2018-03-02 16:44   ` Herbert Xu
2018-03-02 23:15   ` Maciej S. Szmigiero
2018-03-02 23:15     ` Maciej S. Szmigiero
2018-03-02 23:49     ` Hook, Gary
2018-03-02 23:49       ` Hook, Gary
2018-03-02 23:58       ` Maciej S. Szmigiero
2018-03-02 23:58         ` Maciej S. Szmigiero
2018-03-03  0:16         ` Gary R Hook
2018-03-03  0:16           ` Gary R Hook
2018-03-04 12:56     ` Herbert Xu
2018-03-04 12:56       ` Herbert Xu

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