[PATCH 32/33] sctp: add sctp_sock_get_primary_addr

[Christoph Hellwig <hch@xxxxxx>]

Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
space without going through a fake uaccess.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/dlm/lowcomms.c       | 11 +++-----
 include/net/sctp/sctp.h |  1 +
 net/sctp/socket.c       | 57 +++++++++++++++++++++++++----------------
 3 files changed, 39 insertions(+), 30 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 6fa45365666a8..46d2d71b62c57 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -855,10 +855,9 @@ static int tcp_accept_from_sock(struct connection *con)
 static int sctp_accept_from_sock(struct connection *con)
 {
 	/* Check that the new node is in the lockspace */
-	struct sctp_prim prim;
+	struct sctp_prim prim = { };
 	int nodeid;
-	int prim_len, ret;
-	int addr_len;
+	int addr_len, ret;
 	struct connection *newcon;
 	struct connection *addcon;
 	struct socket *newsock;
@@ -876,11 +875,7 @@ static int sctp_accept_from_sock(struct connection *con)
 	if (ret < 0)
 		goto accept_err;
 
-	memset(&prim, 0, sizeof(struct sctp_prim));
-	prim_len = sizeof(struct sctp_prim);
-
-	ret = kernel_getsockopt(newsock, IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
-				(char *)&prim, &prim_len);
+	ret = sctp_sock_get_primary_addr(con->sock->sk, &prim);
 	if (ret < 0) {
 		log_print("getsockopt/sctp_primary_addr failed: %d", ret);
 		goto accept_err;
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index b505fa082f254..c98b1d14db853 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -618,5 +618,6 @@ static inline bool sctp_newsk_ready(const struct sock *sk)
 int sctp_setsockopt_bindx(struct sock *sk, struct sockaddr *kaddrs,
 		int addrs_size, int op);
 void sctp_sock_set_nodelay(struct sock *sk, bool val);
+int sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim);
 
 #endif /* __net_sctp_h__ */
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 64c395f7a86d5..39bf8090dbe1e 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6411,6 +6411,35 @@ static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
 	return err;
 }
 
+static int __sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim)
+{
+	struct sctp_association *asoc;
+
+	asoc = sctp_id2assoc(sk, prim->ssp_assoc_id);
+	if (!asoc)
+		return -EINVAL;
+	if (!asoc->peer.primary_path)
+		return -ENOTCONN;
+
+	memcpy(&prim->ssp_addr, &asoc->peer.primary_path->ipaddr,
+		asoc->peer.primary_path->af_specific->sockaddr_len);
+
+	sctp_get_pf_specific(sk->sk_family)->addr_to_user(sctp_sk(sk),
+			(union sctp_addr *)&prim->ssp_addr);
+	return 0;
+}
+
+int sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim)
+{
+	int ret;
+
+	lock_sock(sk);
+	ret = __sctp_sock_get_primary_addr(sk, prim);
+	release_sock(sk);
+	return ret;
+}
+EXPORT_SYMBOL(sctp_sock_get_primary_addr);
+
 /* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
  *
  * Requests that the local SCTP stack use the enclosed peer address as
@@ -6421,35 +6450,19 @@ static int sctp_getsockopt_primary_addr(struct sock *sk, int len,
 					char __user *optval, int __user *optlen)
 {
 	struct sctp_prim prim;
-	struct sctp_association *asoc;
-	struct sctp_sock *sp = sctp_sk(sk);
+	int ret;
 
 	if (len < sizeof(struct sctp_prim))
 		return -EINVAL;
-
-	len = sizeof(struct sctp_prim);
-
-	if (copy_from_user(&prim, optval, len))
+	if (copy_from_user(&prim, optval, sizeof(struct sctp_prim)))
 		return -EFAULT;
 
-	asoc = sctp_id2assoc(sk, prim.ssp_assoc_id);
-	if (!asoc)
-		return -EINVAL;
-
-	if (!asoc->peer.primary_path)
-		return -ENOTCONN;
-
-	memcpy(&prim.ssp_addr, &asoc->peer.primary_path->ipaddr,
-		asoc->peer.primary_path->af_specific->sockaddr_len);
-
-	sctp_get_pf_specific(sk->sk_family)->addr_to_user(sp,
-			(union sctp_addr *)&prim.ssp_addr);
+	ret = __sctp_sock_get_primary_addr(sk, &prim);
+	if (ret)
+		return ret;
 
-	if (put_user(len, optlen))
+	if (put_user(len, optlen) || copy_to_user(optval, &prim, len))
 		return -EFAULT;
-	if (copy_to_user(optval, &prim, len))
-		return -EFAULT;
-
 	return 0;
 }
 
-- 
2.26.2