From a784c423ea89bf264404c58aa37e2be6338a0e21 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 5 Feb 2024 16:51:42 +0100 Subject: [PATCH] mptcp: fix duplicate subflow creation Fullmesh endpoints could end-up unexpectedly generating duplicate subflows - same local and remote addresses - when multiple incoming ADD_ADDR are processed before the PM creates the subflow for the local endpoints. Address the issue explicitly checking for duplicates at subflow creation time. To avoid a quadratic computational complexity, track the unavailable remote address ids in a temporary bitmap and initialize such bitmap with the remote ids of all the existing subflows matching the local address currently processed. The above allows additionally replacing the existing code checking for duplicate entry in the current set with a simple bit test operation. Fixes: 2843ff6f36db ("mptcp: remote addresses fullmesh") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/435 Signed-off-by: Paolo Abeni --- net/mptcp/pm_netlink.c | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 066bc855365c67..617aad83eb87f2 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -396,19 +396,6 @@ void mptcp_pm_free_anno_list(struct mptcp_sock *msk) } } -static bool lookup_address_in_vec(const struct mptcp_addr_info *addrs, unsigned int nr, - const struct mptcp_addr_info *addr) -{ - int i; - - for (i = 0; i < nr; i++) { - if (addrs[i].id == addr->id) - return true; - } - - return false; -} - /* Fill all the remote addresses into the array addrs[], * and return the array size. */ @@ -440,6 +427,16 @@ static unsigned int fill_remote_addresses_vec(struct mptcp_sock *msk, msk->pm.subflows++; addrs[i++] = remote; } else { + DECLARE_BITMAP(unavail_id, MPTCP_PM_MAX_ADDR_ID + 1); + + /* Forbit creation of new subflows matching existing + * ones, possibly already created by incoming ADD_ADDR + */ + bitmap_zero(unavail_id, MPTCP_PM_MAX_ADDR_ID + 1); + mptcp_for_each_subflow(msk, subflow) + if (READ_ONCE(subflow->local_id) == local->id) + __set_bit(subflow->remote_id, unavail_id); + mptcp_for_each_subflow(msk, subflow) { ssk = mptcp_subflow_tcp_sock(subflow); remote_address((struct sock_common *)ssk, &addrs[i]); @@ -447,11 +444,17 @@ static unsigned int fill_remote_addresses_vec(struct mptcp_sock *msk, if (deny_id0 && !addrs[i].id) continue; + if (test_bit(addrs[i].id, unavail_id)) + continue; + if (!mptcp_pm_addr_families_match(sk, local, &addrs[i])) continue; - if (!lookup_address_in_vec(addrs, i, &addrs[i]) && - msk->pm.subflows < subflows_max) { + if (msk->pm.subflows < subflows_max) { + /* forbit creating multiple address towards + * this id + */ + __set_bit(addrs[i].id, unavail_id); msk->pm.subflows++; i++; }