crypto: user - no parsing of CRYPTO_MSG_GETALG

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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 6 insertions, 4 deletions

diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index 43fe85f20d57..f71960dea882 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;