[PATCH mptcp-next v5 02/14] mptcp: handle local addrs announced by userspace PMs

[Kishen Maloor <kishen.maloor@intel.com>]

This change adds an internal function to store/retrieve local
addrs announced by userspace PM implementations to/from its kernel
context. The function addresses the requirements of three scenarios:
1) ADD_ADDR announcements (which require that a local id be
provided), 2) retrieving the local id associated with an address,
and also where one may need to be assigned, and 3) reissuance of
ADD_ADDRs when there's a successful match of addr/id.

The list of all stored local addr entries is held under the
MPTCP sock structure. Memory for these entries is allocated from
the sock option buffer, so the list of addrs is bounded by optmem_max.
The list if not released via REMOVE_ADDR signals is ultimately
freed when the sock is destructed.

Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
---
 net/mptcp/pm_netlink.c | 72 ++++++++++++++++++++++++++++++++++++++++++
 net/mptcp/protocol.c   |  2 ++
 net/mptcp/protocol.h   |  2 ++
 3 files changed, 76 insertions(+)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 98e59576415b..d8825bf580b7 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -390,6 +390,24 @@ static bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 	return true;
 }
 
+void mptcp_free_local_addr_list(struct mptcp_sock *msk)
+{
+	struct mptcp_pm_addr_entry *entry, *tmp;
+	struct sock *sk = (struct sock *)msk;
+	LIST_HEAD(free_list);
+
+	if (!mptcp_pm_is_userspace(msk))
+		return;
+
+	mptcp_data_lock(sk);
+	list_splice_init(&msk->local_addr_list, &free_list);
+	mptcp_data_unlock(sk);
+
+	list_for_each_entry_safe(entry, tmp, &free_list, list) {
+		sock_kfree_s(sk, entry, sizeof(*entry));
+	}
+}
+
 void mptcp_pm_free_anno_list(struct mptcp_sock *msk)
 {
 	struct mptcp_pm_add_entry *entry, *tmp;
@@ -878,6 +896,60 @@ static void __mptcp_pm_release_addr_entry(struct mptcp_pm_addr_entry *entry)
 	kfree(entry);
 }
 
+static int mptcp_userspace_pm_append_new_local_addr(struct mptcp_sock *msk,
+						    struct mptcp_pm_addr_entry *entry)
+{
+	DECLARE_BITMAP(id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
+	struct mptcp_pm_addr_entry *match = NULL;
+	struct sock *sk = (struct sock *)msk;
+	struct mptcp_pm_addr_entry *e;
+	bool addr_match = false;
+	bool id_match = false;
+	int ret = -EINVAL;
+
+	bitmap_zero(id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
+
+	mptcp_data_lock(sk);
+	list_for_each_entry(e, &msk->local_addr_list, list) {
+		addr_match = addresses_equal(&e->addr, &entry->addr, true);
+		if (addr_match && entry->addr.id == 0)
+			entry->addr.id = e->addr.id;
+		id_match = (e->addr.id == entry->addr.id);
+		if (addr_match && id_match) {
+			match = e;
+			break;
+		} else if (addr_match || id_match) {
+			break;
+		}
+		__set_bit(e->addr.id, id_bitmap);
+	}
+
+	if (!match && !addr_match && !id_match) {
+		/* Memory for the entry is allocated from the
+		 * sock option buffer.
+		 */
+		e = sock_kmalloc(sk, sizeof(*e), GFP_ATOMIC);
+		if (!e) {
+			mptcp_data_unlock(sk);
+			return -ENOMEM;
+		}
+
+		*e = *entry;
+		if (!e->addr.id)
+			e->addr.id = find_next_zero_bit(id_bitmap,
+							MPTCP_PM_MAX_ADDR_ID + 1,
+							1);
+		list_add_tail_rcu(&e->list, &msk->local_addr_list);
+		ret = e->addr.id;
+	} else if (match) {
+		ret = entry->addr.id;
+	}
+
+	mptcp_data_unlock(sk);
+
+	return ret;
+}
+
 static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
 					     struct mptcp_pm_addr_entry *entry)
 {
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 97b0338fe96f..f7661083eee8 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2547,6 +2547,7 @@ static int __mptcp_init_sock(struct sock *sk)
 	INIT_LIST_HEAD(&msk->conn_list);
 	INIT_LIST_HEAD(&msk->join_list);
 	INIT_LIST_HEAD(&msk->rtx_queue);
+	INIT_LIST_HEAD(&msk->local_addr_list);
 	INIT_WORK(&msk->work, mptcp_worker);
 	__skb_queue_head_init(&msk->receive_queue);
 	msk->out_of_order_queue = RB_ROOT;
@@ -3043,6 +3044,7 @@ void mptcp_destroy_common(struct mptcp_sock *msk)
 	msk->rmem_fwd_alloc = 0;
 	mptcp_token_destroy(msk);
 	mptcp_pm_free_anno_list(msk);
+	mptcp_free_local_addr_list(msk);
 }
 
 static void mptcp_destroy(struct sock *sk)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 9b655d049b94..2d18d2e7ee0e 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -281,6 +281,7 @@ struct mptcp_sock {
 	struct sk_buff_head receive_queue;
 	struct list_head conn_list;
 	struct list_head rtx_queue;
+	struct list_head local_addr_list;
 	struct mptcp_data_frag *first_pending;
 	struct list_head join_list;
 	struct socket	*subflow; /* outgoing connect/listener/!mp_capable */
@@ -731,6 +732,7 @@ struct mptcp_sock *mptcp_token_get_sock(struct net *net, u32 token);
 struct mptcp_sock *mptcp_token_iter_next(const struct net *net, long *s_slot,
 					 long *s_num);
 void mptcp_token_destroy(struct mptcp_sock *msk);
+void mptcp_free_local_addr_list(struct mptcp_sock *msk);
 
 void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn);
 
-- 
2.31.1