crypto: user - make NETLINK_CRYPTO work inside netns

Currently, NETLINK_CRYPTO works only in the init network namespace. It
doesn't make much sense to cut it out of the other network namespaces,
so do the minor plumbing work necessary to make it work in any network
namespace. Code inspired by net/core/sock_diag.c.

Tested using kcapi-dgst from libkcapi [1]:
Before:
    # unshare -n kcapi-dgst -c sha256 </dev/null | wc -c
    libkcapi - Error: Netlink error: sendmsg failed
    libkcapi - Error: Netlink error: sendmsg failed
    libkcapi - Error: NETLINK_CRYPTO: cannot obtain cipher information for hmac(sha512) (is required crypto_user.c patch missing? see documentation)
    0

After:
    # unshare -n kcapi-dgst -c sha256 </dev/null | wc -c
    32

[1] https://github.com/smuellerDD/libkcapi

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 3 insertions, 1 deletions

diff --git a/crypto/crypto_user_stat.c b/crypto/crypto_user_stat.c
index a03f326a63d3..8bad88413de1 100644
--- a/crypto/crypto_user_stat.c
+++ b/crypto/crypto_user_stat.c
@@ -10,6 +10,7 @@
 #include <linux/cryptouser.h>
 #include <linux/sched.h>
 #include <net/netlink.h>
+#include <net/sock.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/internal/rng.h>
 #include <crypto/akcipher.h>
@@ -298,6 +299,7 @@ out:
 int crypto_reportstat(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
 		      struct nlattr **attrs)
 {
+	struct net *net = sock_net(in_skb->sk);
 	struct crypto_user_alg *p = nlmsg_data(in_nlh);
 	struct crypto_alg *alg;
 	struct sk_buff *skb;
@@ -329,7 +331,7 @@ drop_alg:
 	if (err)
 		return err;
 
-	return nlmsg_unicast(crypto_nlsk, skb, NETLINK_CB(in_skb).portid);
+	return nlmsg_unicast(net->crypto_nlsk, skb, NETLINK_CB(in_skb).portid);
 }
 
 MODULE_LICENSE("GPL");