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authorPaolo Abeni <pabeni@redhat.com>2020-03-27 14:48:42 -0700
committerDavid S. Miller <davem@davemloft.net>2020-03-29 22:14:48 -0700
commitcc9d2566986692e5b6df1aac88fbf65fe340d432 (patch)
tree3aecfec84f8fa69a2314fe3bcc370274e8b4fab1 /net/mptcp/options.c
parent926bdeab5535856e3a164545630149f212d3482d (diff)
downloadlinux-cc9d2566986692e5b6df1aac88fbf65fe340d432.tar.bz2
mptcp: update per unacked sequence on pkt reception
So that we keep per unacked sequence number consistent; since we update per msk data, use an atomic64 cmpxchg() to protect against concurrent updates from multiple subflows. Initialize the snd_una at connect()/accept() time. Co-developed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Florian Westphal <fw@strlen.de> 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/options.c')
-rw-r--r--net/mptcp/options.c52
1 files changed, 46 insertions, 6 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 20ba00865c55..b0ff8ad702a3 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -744,6 +744,46 @@ fully_established:
return true;
}
+static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
+{
+ u32 old_ack32, cur_ack32;
+
+ if (use_64bit)
+ return cur_ack;
+
+ old_ack32 = (u32)old_ack;
+ cur_ack32 = (u32)cur_ack;
+ cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
+ if (unlikely(before(cur_ack32, old_ack32)))
+ return cur_ack + (1LL << 32);
+ return cur_ack;
+}
+
+static void update_una(struct mptcp_sock *msk,
+ struct mptcp_options_received *mp_opt)
+{
+ u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
+ u64 write_seq = READ_ONCE(msk->write_seq);
+
+ /* avoid ack expansion on update conflict, to reduce the risk of
+ * wrongly expanding to a future ack sequence number, which is way
+ * more dangerous than missing an ack
+ */
+ new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
+
+ /* ACK for data not even sent yet? Ignore. */
+ if (after64(new_snd_una, write_seq))
+ new_snd_una = old_snd_una;
+
+ while (after64(new_snd_una, old_snd_una)) {
+ snd_una = old_snd_una;
+ old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
+ new_snd_una);
+ if (old_snd_una == snd_una)
+ break;
+ }
+}
+
static bool add_addr_hmac_valid(struct mptcp_sock *msk,
struct mptcp_options_received *mp_opt)
{
@@ -805,6 +845,12 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
if (!mp_opt->dss)
return;
+ /* we can't wait for recvmsg() to update the ack_seq, otherwise
+ * monodirectional flows will stuck
+ */
+ if (mp_opt->use_ack)
+ update_una(msk, mp_opt);
+
mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
if (!mpext)
return;
@@ -831,12 +877,6 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
mpext->use_map = 1;
}
- if (mp_opt->use_ack) {
- mpext->data_ack = mp_opt->data_ack;
- mpext->use_ack = 1;
- mpext->ack64 = mp_opt->ack64;
- }
-
mpext->data_fin = mp_opt->data_fin;
}