Commit 8e2760ea authored by Matthieu Baerts (NGI0)'s avatar Matthieu Baerts (NGI0) Committed by Jakub Kicinski
Browse files

Revert "mptcp: add needs_id for netlink appending addr" 

This commit was originally adding the ability to add MPTCP endpoints
with ID 0 by accident. The in-kernel PM, handling MPTCP endpoints at the
net namespace level, is not supposed to handle endpoints with such ID,
because this ID 0 is reserved to the initial subflow, as mentioned in
the MPTCPv1 protocol [1], a per-connection setting.

Note that 'ip mptcp endpoint add id 0' stops early with an error, but
other tools might still request the in-kernel PM to create MPTCP
endpoints with this restricted ID 0.

In other words, it was wrong to call the mptcp_pm_has_addr_attr_id
helper to check whether the address ID attribute is set: if it was set
to 0, a new MPTCP endpoint would be created with ID 0, which is not
expected, and might cause various issues later.

Fixes: 584f3894 ("mptcp: add needs_id for netlink appending addr")
Cc: stable@vger.kernel.org
Link: https://datatracker.ietf.org/doc/html/rfc8684#section-3.2-9

 [1]
Reviewed-by: default avatarGeliang Tang <geliang@kernel.org>
Signed-off-by: default avatarMatthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260407-net-mptcp-revert-pm-needs-id-v2-1-7a25cbc324f8@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 9b55b253

net/mptcp/pm_kernel.c

+5 −19
Original line number Diff line number Diff line
@@ -720,7 +720,7 @@ static void __mptcp_pm_release_addr_entry(struct mptcp_pm_addr_entry *entry) 


static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,

					     struct mptcp_pm_addr_entry *entry,

					     bool needs_id, bool replace)

					     bool replace)

{

	struct mptcp_pm_addr_entry *cur, *del_entry = NULL;

	int ret = -EINVAL;
@@ -779,7 +779,7 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet, 
		}

	}



	if (!entry->addr.id && needs_id) {

	if (!entry->addr.id) {

find_next:

		entry->addr.id = find_next_zero_bit(pernet->id_bitmap,

						    MPTCP_PM_MAX_ADDR_ID + 1,
@@ -790,7 +790,7 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet, 
		}

	}



	if (!entry->addr.id && needs_id)

	if (!entry->addr.id)

		goto out;



	__set_bit(entry->addr.id, pernet->id_bitmap);
@@ -923,7 +923,7 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, 
		return -ENOMEM;



	entry->addr.port = 0;

	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, true, false);

	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, false);

	if (ret < 0)

		kfree(entry);
@@ -977,18 +977,6 @@ static int mptcp_nl_add_subflow_or_signal_addr(struct net *net, 
	return 0;

}



static bool mptcp_pm_has_addr_attr_id(const struct nlattr *attr,

				      struct genl_info *info)

{

	struct nlattr *tb[MPTCP_PM_ADDR_ATTR_MAX + 1];



	if (!nla_parse_nested_deprecated(tb, MPTCP_PM_ADDR_ATTR_MAX, attr,

					 mptcp_pm_address_nl_policy, info->extack) &&

	    tb[MPTCP_PM_ADDR_ATTR_ID])

		return true;

	return false;

}



/* Add an MPTCP endpoint */

int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info)

{
@@ -1037,9 +1025,7 @@ int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info) 
			goto out_free;

		}

	}

	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry,

						!mptcp_pm_has_addr_attr_id(attr, info),

						true);

	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry, true);

	if (ret < 0) {

		GENL_SET_ERR_MSG_FMT(info, "too many addresses or duplicate one: %d", ret);

		goto out_free;