Patch "mptcp: allow changing the "backup" bit by endpoint id" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mptcp: allow changing the "backup" bit by endpoint id

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mptcp-allow-changing-the-backup-bit-by-endpoint-id.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2963809f8d48c2726da96f52457b92f3c68f4e29
Author: Davide Caratti <dcaratti@xxxxxxxxxx>
Date:   Fri Dec 3 14:35:36 2021 -0800

    mptcp: allow changing the "backup" bit by endpoint id
    
    [ Upstream commit 602837e8479d20d49559b4b97b79d34c0efe7ecb ]
    
    a non-zero 'id' is sufficient to identify MPTCP endpoints: allow changing
    the value of 'backup' bit by simply specifying the endpoint id.
    
    Link: https://github.com/multipath-tcp/mptcp_net-next/issues/158
    Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
    Signed-off-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index d96860053816a..3be10bf22cf7c 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1711,22 +1711,28 @@ static int mptcp_nl_addr_backup(struct net *net,
 
 static int mptcp_nl_cmd_set_flags(struct sk_buff *skb, struct genl_info *info)
 {
+	struct mptcp_pm_addr_entry addr = { .addr = { .family = AF_UNSPEC }, }, *entry;
 	struct nlattr *attr = info->attrs[MPTCP_PM_ATTR_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
-	struct mptcp_pm_addr_entry addr, *entry;
 	struct net *net = sock_net(skb->sk);
-	u8 bkup = 0;
+	u8 bkup = 0, lookup_by_id = 0;
 	int ret;
 
-	ret = mptcp_pm_parse_addr(attr, info, true, &addr);
+	ret = mptcp_pm_parse_addr(attr, info, false, &addr);
 	if (ret < 0)
 		return ret;
 
 	if (addr.flags & MPTCP_PM_ADDR_FLAG_BACKUP)
 		bkup = 1;
+	if (addr.addr.family == AF_UNSPEC) {
+		lookup_by_id = 1;
+		if (!addr.addr.id)
+			return -EOPNOTSUPP;
+	}
 
 	list_for_each_entry(entry, &pernet->local_addr_list, list) {
-		if (addresses_equal(&entry->addr, &addr.addr, true)) {
+		if ((!lookup_by_id && addresses_equal(&entry->addr, &addr.addr, true)) ||
+		    (lookup_by_id && entry->addr.id == addr.addr.id)) {
 			mptcp_nl_addr_backup(net, &entry->addr, bkup);
 
 			if (bkup)