[PATCH] crypto: user - no parsing of CRYPTO_MSG_GETALG

[PATCH] crypto: user - no parsing of CRYPTO_MSG_GETALG

[Stephan Mueller]

The CRYPTO_MSG_GETALG netlink message type provides a buffer to the
kernel to retrieve information from the kernel. The data buffer will not
provide any input and will not be read. Hence the nlmsg_parse is not
applicable to this netlink message type.

This patch fixes the following kernel log message when using this
netlink interface:

netlink: 208 bytes leftover after parsing attributes in process `XXX'.

Patch successfully tested with libkcapi from [1] which uses
CRYPTO_MSG_GETALG to obtain cipher-specific information from the kernel.

[1] http://www.chronox.de/libkcapi.html

Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
 crypto/crypto_user.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index 43fe85f..f71960d 100644
--- a/crypto/crypto_user.c
+++ b/crypto/crypto_user.c
@@ -516,10 +516,12 @@ static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		return err;
 	}
 
-	err = nlmsg_parse(nlh, crypto_msg_min[type], attrs, CRYPTOCFGA_MAX,
-			  crypto_policy);
-	if (err < 0)
-		return err;
+	if (type != (CRYPTO_MSG_GETALG - CRYPTO_MSG_BASE)) {
+		err = nlmsg_parse(nlh, crypto_msg_min[type], attrs,
+				  CRYPTOCFGA_MAX, crypto_policy);
+		if (err < 0)
+			return err;
+	}
 
 	if (link->doit == NULL)
 		return -EINVAL;
-- 
2.5.5

Re: [PATCH] crypto: user - no parsing of CRYPTO_MSG_GETALG

[Herbert Xu]

On Mon, May 16, 2016 at 02:53:36AM +0200, Stephan Mueller wrote:
> The CRYPTO_MSG_GETALG netlink message type provides a buffer to the
> kernel to retrieve information from the kernel. The data buffer will not
> provide any input and will not be read. Hence the nlmsg_parse is not
> applicable to this netlink message type.
> 
> This patch fixes the following kernel log message when using this
> netlink interface:
> 
> netlink: 208 bytes leftover after parsing attributes in process `XXX'.
> 
> Patch successfully tested with libkcapi from [1] which uses
> CRYPTO_MSG_GETALG to obtain cipher-specific information from the kernel.
> 
> [1] http://www.chronox.de/libkcapi.html
> 
> Signed-off-by: Stephan Mueller <smueller@chronox.de>

Applied.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt