The patch below does not apply to the 6.1-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-6.1.y git checkout FETCH_HEAD git cherry-pick -x a7cfe776637004a4c938fde78be4bd608c32c3ef # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024022609-elongated-activity-64a1@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

a7cfe7766370 ("mptcp: fix data races on local_id") 84c531f54ad9 ("mptcp: userspace pm send RM_ADDR for ID 0") f1f26512a9bf ("mptcp: use plain bool instead of custom binary enum") 1e07938e29c5 ("net: mptcp: rename netlink handlers to mptcp_pm_nl_<blah>_{doit,dumpit}") 1d0507f46843 ("net: mptcp: convert netlink from small_ops to ops") fce68b03086f ("mptcp: add scheduled in mptcp_subflow_context") 1730b2b2c5a5 ("mptcp: add sched in mptcp_sock") 740ebe35bd3f ("mptcp: add struct mptcp_sched_ops") a7384f391875 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")

thanks,

greg k-h

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

From a7cfe776637004a4c938fde78be4bd608c32c3ef Mon Sep 17 00:00:00 2001 From: Paolo Abeni pabeni@redhat.com Date: Thu, 15 Feb 2024 19:25:31 +0100 Subject: [PATCH] mptcp: fix data races on local_id

The local address id is accessed lockless by the NL PM, add all the required ONCE annotation. There is a caveat: the local id can be initialized late in the subflow life-cycle, and its validity is controlled by the local_id_valid flag.

Remove such flag and encode the validity in the local_id field itself with negative value before initialization. That allows accessing the field consistently with a single read operation.

Fixes: 0ee4261a3681 ("mptcp: implement mptcp_pm_remove_subflow") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c index e57c5f47f035..6ff6f14674aa 100644 --- a/net/mptcp/diag.c +++ b/net/mptcp/diag.c @@ -65,7 +65,7 @@ static int subflow_get_info(struct sock *sk, struct sk_buff *skb) sf->map_data_len) || nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_FLAGS, flags) || nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_REM, sf->remote_id) || - nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_LOC, sf->local_id)) { + nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_LOC, subflow_get_local_id(sf))) { err = -EMSGSIZE; goto nla_failure; } diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index a24c9128dee9..912e25077437 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -800,7 +800,7 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk, mptcp_for_each_subflow_safe(msk, subflow, tmp) { struct sock *ssk = mptcp_subflow_tcp_sock(subflow); int how = RCV_SHUTDOWN | SEND_SHUTDOWN; - u8 id = subflow->local_id; + u8 id = subflow_get_local_id(subflow);

if (rm_type == MPTCP_MIB_RMADDR && subflow->remote_id != rm_id) continue; @@ -809,7 +809,7 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk,

pr_debug(" -> %s rm_list_ids[%d]=%u local_id=%u remote_id=%u mpc_id=%u", rm_type == MPTCP_MIB_RMADDR ? "address" : "subflow", - i, rm_id, subflow->local_id, subflow->remote_id, + i, rm_id, id, subflow->remote_id, msk->mpc_endpoint_id); spin_unlock_bh(&msk->pm.lock); mptcp_subflow_shutdown(sk, ssk, how); @@ -1994,7 +1994,7 @@ static int mptcp_event_add_subflow(struct sk_buff *skb, const struct sock *ssk) if (WARN_ON_ONCE(!sf)) return -EINVAL;

- if (nla_put_u8(skb, MPTCP_ATTR_LOC_ID, sf->local_id)) + if (nla_put_u8(skb, MPTCP_ATTR_LOC_ID, subflow_get_local_id(sf))) return -EMSGSIZE;

if (nla_put_u8(skb, MPTCP_ATTR_REM_ID, sf->remote_id)) diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c index e582b3b2d174..d396a5973429 100644 --- a/net/mptcp/pm_userspace.c +++ b/net/mptcp/pm_userspace.c @@ -234,7 +234,7 @@ static int mptcp_userspace_pm_remove_id_zero_address(struct mptcp_sock *msk,

lock_sock(sk); mptcp_for_each_subflow(msk, subflow) { - if (subflow->local_id == 0) { + if (READ_ONCE(subflow->local_id) == 0) { has_id_0 = true; break; } diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 8ef2927ebca2..948606a537da 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -85,7 +85,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk) subflow->subflow_id = msk->subflow_id++;

/* This is the first subflow, always with id 0 */ - subflow->local_id_valid = 1; + WRITE_ONCE(subflow->local_id, 0); mptcp_sock_graft(msk->first, sk->sk_socket); iput(SOCK_INODE(ssock));

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index ed50f2015dc3..631a7f445f34 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -491,10 +491,9 @@ struct mptcp_subflow_context { remote_key_valid : 1, /* received the peer key from */ disposable : 1, /* ctx can be free at ulp release time */ stale : 1, /* unable to snd/rcv data, do not use for xmit */ - local_id_valid : 1, /* local_id is correctly initialized */ valid_csum_seen : 1, /* at least one csum validated */ is_mptfo : 1, /* subflow is doing TFO */ - __unused : 9; + __unused : 10; bool data_avail; bool scheduled; u32 remote_nonce; @@ -505,7 +504,7 @@ struct mptcp_subflow_context { u8 hmac[MPTCPOPT_HMAC_LEN]; /* MPJ subflow only */ u64 iasn; /* initial ack sequence number, MPC subflows only */ }; - u8 local_id; + s16 local_id; /* if negative not initialized yet */ u8 remote_id; u8 reset_seen:1; u8 reset_transient:1; @@ -556,6 +555,7 @@ mptcp_subflow_ctx_reset(struct mptcp_subflow_context *subflow) { memset(&subflow->reset, 0, sizeof(subflow->reset)); subflow->request_mptcp = 1; + WRITE_ONCE(subflow->local_id, -1); }

static inline u64 @@ -1022,6 +1022,15 @@ 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);

+static inline u8 subflow_get_local_id(const struct mptcp_subflow_context *subflow) +{ + int local_id = READ_ONCE(subflow->local_id); + + if (local_id < 0) + return 0; + return local_id; +} + void __init mptcp_pm_nl_init(void); void mptcp_pm_nl_work(struct mptcp_sock *msk); void mptcp_pm_nl_rm_subflow_received(struct mptcp_sock *msk, diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index c34ecadee120..015184bbf06c 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -577,8 +577,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)

static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id) { - subflow->local_id = local_id; - subflow->local_id_valid = 1; + WARN_ON_ONCE(local_id < 0 || local_id > 255); + WRITE_ONCE(subflow->local_id, local_id); }

static int subflow_chk_local_id(struct sock *sk) @@ -587,7 +587,7 @@ static int subflow_chk_local_id(struct sock *sk) struct mptcp_sock *msk = mptcp_sk(subflow->conn); int err;

- if (likely(subflow->local_id_valid)) + if (likely(subflow->local_id >= 0)) return 0;

err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk); @@ -1731,6 +1731,7 @@ static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk, pr_debug("subflow=%p", ctx);

ctx->tcp_sock = sk; + WRITE_ONCE(ctx->local_id, -1);

return ctx; } @@ -1966,7 +1967,7 @@ static void subflow_ulp_clone(const struct request_sock *req, new_ctx->idsn = subflow_req->idsn;

/* this is the first subflow, id is always 0 */ - new_ctx->local_id_valid = 1; + subflow_set_local_id(new_ctx, 0); } else if (subflow_req->mp_join) { new_ctx->ssn_offset = subflow_req->ssn_offset; new_ctx->mp_join = 1;