The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6834097fc38c5416701c793da94558cea49c0a1f # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024080728-steep-scallion-4de3@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

6834097fc38c ("mptcp: pm: fix backup support in signal endpoints") 9ae7846c4b6b ("mptcp: dump addrs in userspace pm list") 34e74a5cf3b7 ("mptcp: implement mptcp_userspace_pm_dump_addr") aab4d8564947 ("net: mptcp: use policy generated by YAML spec") 1e07938e29c5 ("net: mptcp: rename netlink handlers to mptcp_pm_nl_<blah>_{doit,dumpit}") 1d0507f46843 ("net: mptcp: convert netlink from small_ops to ops") 740ebe35bd3f ("mptcp: add struct mptcp_sched_ops") 6ba7ce89905c ("mptcp: unify pm set_flags interfaces") f40be0db0b76 ("mptcp: unify pm get_flags_and_ifindex_by_id") a963853fd465 ("mptcp: use net instead of sock_net") dfc8d0603033 ("mptcp: implement delayed seq generation for passive fastopen") d15697185404 ("mptcp: allow privileged operations from user namespaces") 9c5d03d36251 ("genetlink: start to validate reserved header bytes") 02739545951a ("net: Fix data-races around sysctl_[rw]mem(_offset)?.") 892f396c8e68 ("mptcp: netlink: issue MP_PRIO signals from userspace PMs") a657430260e5 ("mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags") c21b50d5912b ("mptcp: Avoid acquiring PM lock for subflow priority changes") 6f664045c868 ("Merge tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6834097fc38c5416701c793da94558cea49c0a1f Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" matttbe@kernel.org Date: Sat, 27 Jul 2024 12:01:28 +0200 Subject: [PATCH] mptcp: pm: fix backup support in signal endpoints

There was a support for signal endpoints, but only when the endpoint's flag was changed during a connection. If an endpoint with the signal and backup was already present, the MP_JOIN reply was not containing the backup flag as expected.

That's confusing to have this inconsistent behaviour. On the other hand, the infrastructure to set the backup flag in the SYN + ACK + MP_JOIN was already there, it was just never set before. Now when requesting the local ID from the path-manager, the backup status is also requested.

Note that when the userspace PM is used, the backup flag can be set if the local address was already used before with a backup flag, e.g. if the address was announced with the 'backup' flag, or a subflow was created with the 'backup' flag.

Fixes: 4596a2c1b7f5 ("mptcp: allow creating non-backup subflows") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/507 Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index 55406720c607..23bb89c94e90 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -426,6 +426,18 @@ int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc) return mptcp_pm_nl_get_local_id(msk, &skc_local); }

+bool mptcp_pm_is_backup(struct mptcp_sock *msk, struct sock_common *skc) +{ + struct mptcp_addr_info skc_local; + + mptcp_local_address((struct sock_common *)skc, &skc_local); + + if (mptcp_pm_is_userspace(msk)) + return mptcp_userspace_pm_is_backup(msk, &skc_local); + + return mptcp_pm_nl_is_backup(msk, &skc_local); +} + int mptcp_pm_get_flags_and_ifindex_by_id(struct mptcp_sock *msk, unsigned int id, u8 *flags, int *ifindex) { diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 7635fac91539..37954a0b087d 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -1101,6 +1101,24 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc return ret; }

+bool mptcp_pm_nl_is_backup(struct mptcp_sock *msk, struct mptcp_addr_info *skc) +{ + struct pm_nl_pernet *pernet = pm_nl_get_pernet_from_msk(msk); + struct mptcp_pm_addr_entry *entry; + bool backup = false; + + rcu_read_lock(); + list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) { + if (mptcp_addresses_equal(&entry->addr, skc, entry->addr.port)) { + backup = !!(entry->flags & MPTCP_PM_ADDR_FLAG_BACKUP); + break; + } + } + rcu_read_unlock(); + + return backup; +} + #define MPTCP_PM_CMD_GRP_OFFSET 0 #define MPTCP_PM_EV_GRP_OFFSET 1

diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c index f0a4590506c6..8eaa9fbe3e34 100644 --- a/net/mptcp/pm_userspace.c +++ b/net/mptcp/pm_userspace.c @@ -165,6 +165,24 @@ int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk, return mptcp_userspace_pm_append_new_local_addr(msk, &new_entry, true); }

+bool mptcp_userspace_pm_is_backup(struct mptcp_sock *msk, + struct mptcp_addr_info *skc) +{ + struct mptcp_pm_addr_entry *entry; + bool backup = false; + + spin_lock_bh(&msk->pm.lock); + list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) { + if (mptcp_addresses_equal(&entry->addr, skc, false)) { + backup = !!(entry->flags & MPTCP_PM_ADDR_FLAG_BACKUP); + break; + } + } + spin_unlock_bh(&msk->pm.lock); + + return backup; +} + int mptcp_pm_nl_announce_doit(struct sk_buff *skb, struct genl_info *info) { struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN]; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index b8b25124e7de..60c6b073d65f 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -1109,6 +1109,9 @@ bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining, int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc); int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc); int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc); +bool mptcp_pm_is_backup(struct mptcp_sock *msk, struct sock_common *skc); +bool mptcp_pm_nl_is_backup(struct mptcp_sock *msk, struct mptcp_addr_info *skc); +bool mptcp_userspace_pm_is_backup(struct mptcp_sock *msk, struct mptcp_addr_info *skc); int mptcp_pm_dump_addr(struct sk_buff *msg, struct netlink_callback *cb); int mptcp_pm_nl_dump_addr(struct sk_buff *msg, struct netlink_callback *cb); diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index be406197b1c4..0e4b5bfbeaa1 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -100,6 +100,7 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req) return NULL; } subflow_req->local_id = local_id; + subflow_req->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)req);

return msk; } @@ -620,6 +621,8 @@ static int subflow_chk_local_id(struct sock *sk) return err;

subflow_set_local_id(subflow, err); + subflow->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)sk); + return 0; }