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authorPaolo Abeni <pabeni@redhat.com>2021-06-10 15:59:41 -0700
committerDavid S. Miller <davem@davemloft.net>2021-06-10 16:47:44 -0700
commit99d1055ce2469dca3dd14be0991ff8133e25e3d0 (patch)
tree6e9c1abe8206b353d21f387100e429a36d785c52 /net/mptcp/subflow.c
parent72f961320d5d15bfcb26dbe3edaa3f7d25fd2c8a (diff)
downloadlinux-99d1055ce2469dca3dd14be0991ff8133e25e3d0.tar.bz2
mptcp: wake-up readers only for in sequence data
Currently we rely on the subflow->data_avail field, which is subject to races: ssk1 skb len = 500 DSS(seq=1, len=1000, off=0) # data_avail == MPTCP_SUBFLOW_DATA_AVAIL ssk2 skb len = 500 DSS(seq = 501, len=1000) # data_avail == MPTCP_SUBFLOW_DATA_AVAIL ssk1 skb len = 500 DSS(seq = 1, len=1000, off =500) # still data_avail == MPTCP_SUBFLOW_DATA_AVAIL, # as the skb is covered by a pre-existing map, # which was in-sequence at reception time. Instead we can explicitly check if some has been received in-sequence, propagating the info from __mptcp_move_skbs_from_subflow(). Additionally add the 'ONCE' annotation to the 'data_avail' memory access, as msk will read it outside the subflow socket lock. Fixes: 648ef4b88673 ("mptcp: Implement MPTCP receive path") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp/subflow.c')
-rw-r--r--net/mptcp/subflow.c23
1 files changed, 9 insertions, 14 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index ef3d037f984a..ebb898acd65a 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1000,7 +1000,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
struct sk_buff *skb;
if (!skb_peek(&ssk->sk_receive_queue))
- subflow->data_avail = 0;
+ WRITE_ONCE(subflow->data_avail, 0);
if (subflow->data_avail)
return true;
@@ -1039,18 +1039,13 @@ static bool subflow_check_data_avail(struct sock *ssk)
ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
ack_seq);
- if (ack_seq == old_ack) {
- subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
- break;
- } else if (after64(ack_seq, old_ack)) {
- subflow->data_avail = MPTCP_SUBFLOW_OOO_DATA;
- break;
+ if (unlikely(before64(ack_seq, old_ack))) {
+ mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
+ continue;
}
- /* only accept in-sequence mapping. Old values are spurious
- * retransmission
- */
- mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
+ WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
+ break;
}
return true;
@@ -1070,7 +1065,7 @@ fallback:
subflow->reset_transient = 0;
subflow->reset_reason = MPTCP_RST_EMPTCP;
tcp_send_active_reset(ssk, GFP_ATOMIC);
- subflow->data_avail = 0;
+ WRITE_ONCE(subflow->data_avail, 0);
return false;
}
@@ -1080,7 +1075,7 @@ fallback:
subflow->map_seq = READ_ONCE(msk->ack_seq);
subflow->map_data_len = skb->len;
subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
- subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
+ WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL);
return true;
}
@@ -1092,7 +1087,7 @@ bool mptcp_subflow_data_available(struct sock *sk)
if (subflow->map_valid &&
mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
subflow->map_valid = 0;
- subflow->data_avail = 0;
+ WRITE_ONCE(subflow->data_avail, 0);
pr_debug("Done with mapping: seq=%u data_len=%u",
subflow->map_subflow_seq,