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Subject[PATCH 06/10] af_unix: Deliver message to several recipients in case of multicast
Date
From: Alban Crequy <alban.crequy@collabora.co.uk>

unix_dgram_sendmsg() implements the delivery both for SOCK_DGRAM and
SOCK_SEQPACKET unix sockets.

The delivery is done in an atomic way; either the message is delivered to all
recipients or none, even in case of interruptions or errors.

Signed-off-by: Alban Crequy <alban.crequy@collabora.co.uk>
Signed-off-by: Ian Molton <ian.molton@collabora.co.uk>
---
net/unix/af_unix.c | 242 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 242 insertions(+), 0 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index f2713d5..a6b489c 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1722,6 +1722,210 @@ static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
}
}

+#ifdef CONFIG_UNIX_MULTICAST
+static void kfree_skb_sock_set(struct sock_set *set)
+{
+ int i;
+ for (i = set->offset ; i < set->cnt ; i++) {
+ if (set->items[i].skb) {
+ kfree_skb(set->items[i].skb);
+ set->items[i].skb = NULL;
+ }
+ }
+}
+
+static void unix_mcast_lock(struct unix_mcast_group *group,
+ struct sock_set *set)
+{
+ int i;
+ for (i = 0 ; i < MCAST_LOCK_CLASS_COUNT ; i++) {
+ if (set->hash & (1 << i))
+ spin_lock_nested(&group->lock[i], i);
+ }
+}
+
+static void unix_mcast_unlock(struct unix_mcast_group *group,
+ struct sock_set *set)
+{
+ int i;
+ for (i = MCAST_LOCK_CLASS_COUNT - 1 ; i >= 0 ; i--) {
+ if (set->hash & (1 << i))
+ spin_unlock(&group->lock[i]);
+ }
+}
+
+
+static int unix_dgram_sendmsg_multicast(struct sock_iocb *siocb,
+ struct sock *sk,
+ struct sk_buff *skb,
+ struct unix_mcast_group *group,
+ struct sock_set *others_set,
+ size_t len,
+ int max_level,
+ long timeo)
+{
+ int err;
+ int i;
+
+ BUG_ON(!others_set);
+
+restart:
+ for (i = others_set->offset ; i < others_set->cnt ; i++) {
+ struct sock *cur = others_set->items[i].s;
+ unsigned int pkt_len;
+ struct sk_filter *filter;
+
+ if (!others_set->items[i].to_deliver)
+ continue;
+
+ BUG_ON(others_set->items[i].skb);
+ BUG_ON(cur == NULL);
+
+ rcu_read_lock();
+ filter = rcu_dereference(cur->sk_filter);
+ if (filter)
+ pkt_len = sk_run_filter(skb, filter->insns);
+ else
+ pkt_len = 0xffffffff;
+ rcu_read_unlock();
+
+ if (pkt_len == 0) {
+ others_set->items[i].to_deliver = 0;
+ continue;
+ }
+
+ others_set->items[i].skb = skb_clone(skb, GFP_KERNEL);
+ if (!others_set->items[i].skb) {
+ kfree_skb_sock_set(others_set);
+ err = -ENOMEM;
+ goto out_free;
+ }
+ skb_set_owner_w(others_set->items[i].skb, sk);
+ err = unix_scm_to_skb(siocb->scm, others_set->items[i].skb,
+ true);
+ if (err < 0)
+ goto out_free;
+ unix_get_secdata(siocb->scm, others_set->items[i].skb);
+ pskb_trim(others_set->items[i].skb, pkt_len);
+ }
+
+ for (i = others_set->offset ; i < others_set->cnt ; i++) {
+ struct sock *cur = others_set->items[i].s;
+
+ if (!others_set->items[i].to_deliver)
+ continue;
+
+ unix_state_lock(cur);
+
+ if (cur->sk_shutdown & RCV_SHUTDOWN) {
+ unix_state_unlock(cur);
+ kfree_skb(others_set->items[i].skb);
+ others_set->items[i].skb = NULL;
+ others_set->items[i].to_deliver = 0;
+ continue;
+ }
+
+ if (sk->sk_type != SOCK_SEQPACKET) {
+ err = security_unix_may_send(sk->sk_socket,
+ cur->sk_socket);
+ if (err) {
+ unix_state_unlock(cur);
+ kfree_skb(others_set->items[i].skb);
+ others_set->items[i].skb = NULL;
+ others_set->items[i].to_deliver = 0;
+ continue;
+ }
+ }
+
+ if (unix_peer(cur) != sk && unix_recvq_full(cur)) {
+ kfree_skb(others_set->items[i].skb);
+ others_set->items[i].skb = NULL;
+
+ if (others_set->items[i].flags
+ & UNIX_MREQ_DROP_WHEN_FULL) {
+ /* Drop the skbs and continue */
+ unix_state_unlock(cur);
+ others_set->items[i].to_deliver = 0;
+ continue;
+ } else {
+ if (!timeo) {
+ unix_state_unlock(cur);
+ err = -EAGAIN;
+ goto out_free;
+ }
+
+ timeo = unix_wait_for_peer(cur, timeo);
+
+ err = sock_intr_errno(timeo);
+ if (signal_pending(current))
+ goto out_free;
+
+ kfree_skb_sock_set(others_set);
+ goto restart;
+ }
+ }
+ unix_state_unlock(cur);
+ }
+
+ unix_mcast_lock(group, others_set);
+ for (i = others_set->offset ; i < others_set->cnt ; i++) {
+ struct sock *cur = others_set->items[i].s;
+
+ if (!others_set->items[i].to_deliver)
+ continue;
+
+ BUG_ON(cur == NULL);
+ BUG_ON(others_set->items[i].skb == NULL);
+
+ unix_state_lock(cur);
+
+ if (sock_flag(cur, SOCK_DEAD)) {
+ unix_state_unlock(cur);
+
+ kfree_skb(others_set->items[i].skb);
+ others_set->items[i].skb = NULL;
+ others_set->items[i].to_deliver = 0;
+ continue;
+ }
+
+ if (sock_flag(cur, SOCK_RCVTSTAMP))
+ __net_timestamp(others_set->items[i].skb);
+
+ skb_queue_tail(&cur->sk_receive_queue,
+ others_set->items[i].skb);
+ others_set->items[i].skb = NULL;
+ if (max_level > unix_sk(cur)->recursion_level)
+ unix_sk(cur)->recursion_level = max_level;
+
+ unix_state_unlock(cur);
+ }
+ unix_mcast_unlock(group, others_set);
+
+ for (i = others_set->offset ; i < others_set->cnt ; i++) {
+ struct sock *cur = others_set->items[i].s;
+
+ if (!others_set->items[i].to_deliver)
+ continue;
+
+ cur->sk_data_ready(cur, len);
+ }
+
+ kfree_skb(skb);
+ scm_destroy(siocb->scm);
+ up_sock_set(others_set);
+ return len;
+
+out_free:
+ kfree_skb(skb);
+ if (others_set) {
+ kfree_skb_sock_set(others_set);
+ up_sock_set(others_set);
+ }
+ return err;
+}
+#endif
+
+
/*
* Send AF_UNIX data.
*/
@@ -1742,6 +1946,10 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
long timeo;
struct scm_cookie tmp_scm;
int max_level;
+#ifdef CONFIG_UNIX_MULTICAST
+ struct unix_mcast_group *group = NULL;
+ struct sock_set *others_set = NULL;
+#endif

if (NULL == siocb->scm)
siocb->scm = &tmp_scm;
@@ -1763,8 +1971,20 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
sunaddr = NULL;
err = -ENOTCONN;
other = unix_peer_get(sk);
+
if (!other)
goto out;
+
+#ifdef CONFIG_UNIX_MULTICAST
+ group = unix_sk(other)->mcast_group;
+ if (group) {
+ others_set = unix_find_multicast_recipients(sk,
+ group, &err);
+
+ if (!others_set)
+ goto out;
+ }
+#endif
}

if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr
@@ -1802,6 +2022,28 @@ restart:
hash, &err);
if (other == NULL)
goto out_free;
+
+#ifdef CONFIG_UNIX_MULTICAST
+ group = unix_sk(other)->mcast_group;
+ if (group) {
+ others_set = unix_find_multicast_recipients(sk,
+ group, &err);
+
+ sock_put(other);
+ other = NULL;
+
+ if (!others_set)
+ goto out;
+ }
+ }
+
+ if (group) {
+ err = unix_dgram_sendmsg_multicast(siocb, sk, skb, group,
+ others_set, len, max_level, timeo);
+ if (err < 0)
+ goto out;
+ return err;
+#endif
}

if (sk_filter(other, skb) < 0) {
--
1.7.7.6


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