[PATCH] dlm, sctp: Do not allocate a fd for peeloff

[Benjamin Poirier <bpoirier@suse.de>]

avoids allocating a fd that a) propagates to every kernel thread and
usermodehelper b) is not properly released.

References: http://article.gmane.org/gmane.linux.network.drbd/22529
Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
---
 fs/dlm/lowcomms.c       |   28 ++++++++++++++--------------
 include/net/sctp/sctp.h |    1 +
 net/sctp/socket.c       |    5 +++--
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 0b3109e..f6645b2 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -52,6 +52,7 @@
 #include <linux/mutex.h>
 #include <linux/sctp.h>
 #include <linux/slab.h>
+#include <net/sctp/sctp.h>
 #include <net/sctp/user.h>
 #include <net/ipv6.h>
 
@@ -474,9 +475,8 @@ static void process_sctp_notification(struct connection *con,
 			int prim_len, ret;
 			int addr_len;
 			struct connection *new_con;
-			sctp_peeloff_arg_t parg;
-			int parglen = sizeof(parg);
-			int err;
+			sctp_assoc_t associd;
+			struct sctp_association *asoc;
 
 			/*
 			 * We get this before any data for an association.
@@ -525,23 +525,23 @@ static void process_sctp_notification(struct connection *con,
 				return;
 
 			/* Peel off a new sock */
-			parg.associd = sn->sn_assoc_change.sac_assoc_id;
-			ret = kernel_getsockopt(con->sock, IPPROTO_SCTP,
-						SCTP_SOCKOPT_PEELOFF,
-						(void *)&parg, &parglen);
+			sctp_lock_sock(con->sock->sk);
+			associd = sn->sn_assoc_change.sac_assoc_id;
+			asoc = sctp_id2assoc(con->sock->sk, associd);
+			if (!asoc) {
+				log_print("sctp_id2assoc error");
+				sctp_release_sock(con->sock->sk);
+				return;
+			}
+			ret = sctp_do_peeloff(asoc, &new_con->sock);
+			sctp_release_sock(con->sock->sk);
 			if (ret < 0) {
 				log_print("Can't peel off a socket for "
 					  "connection %d to node %d: err=%d",
-					  parg.associd, nodeid, ret);
-				return;
-			}
-			new_con->sock = sockfd_lookup(parg.sd, &err);
-			if (!new_con->sock) {
-				log_print("sockfd_lookup error %d", err);
+					  associd, nodeid, ret);
 				return;
 			}
 			add_sock(new_con->sock, new_con);
-			sockfd_put(new_con->sock);
 
 			log_print("connecting to %d sctp association %d",
 				 nodeid, (int)sn->sn_assoc_change.sac_assoc_id);
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index d368561..31e36db 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -413,6 +413,7 @@ static inline sctp_assoc_t sctp_assoc2id(const struct sctp_association *asoc)
 /* Look up the association by its id.  */
 struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id);
 
+int sctp_do_peeloff(struct sctp_association *asoc, struct socket **sockp);
 
 /* A macro to walk a list of skbs.  */
 #define sctp_skb_for_each(pos, head, tmp) \
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 408ebd0..ae8944c 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -239,6 +239,7 @@ struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id)
 
 	return asoc;
 }
+EXPORT_SYMBOL(sctp_id2assoc);
 
 /* Look up the transport from an address and an assoc id. If both address and
  * id are specified, the associations matching the address and the id should be
@@ -4170,8 +4171,7 @@ static int sctp_getsockopt_autoclose(struct sock *sk, int len, char __user *optv
 }
 
 /* Helper routine to branch off an association to a new socket.  */
-SCTP_STATIC int sctp_do_peeloff(struct sctp_association *asoc,
-				struct socket **sockp)
+int sctp_do_peeloff(struct sctp_association *asoc, struct socket **sockp)
 {
 	struct sock *sk = asoc->base.sk;
 	struct socket *sock;
@@ -4206,6 +4206,7 @@ SCTP_STATIC int sctp_do_peeloff(struct sctp_association *asoc,
 
 	return err;
 }
+EXPORT_SYMBOL(sctp_do_peeloff);
 
 static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval, int __user *optlen)
 {
-- 
1.7.7