From: Ilpo Järvinen <ij@xxxxxxxxxx>
The heuristic algorithm from draft-11 Appendix A.2.2 to
mitigate against false ACE field overflows.
Signed-off-by: Ilpo Järvinen <ij@xxxxxxxxxx>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@xxxxxxxxxxxxxxxxxxx>
---
include/net/tcp.h | 1 +
net/ipv4/tcp_input.c | 18 ++++++++++++++++--
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index a2c330afa883..454b2254a64a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -247,6 +247,7 @@ static_assert((1 << ATO_BITS) > TCP_DELACK_MAX);
#define TCP_ACCECN_MAXSIZE (TCPOLEN_ACCECN_BASE + \
TCPOLEN_ACCECN_PERFIELD * \
TCP_ACCECN_NUMFIELDS)
+#define TCP_ACCECN_SAFETY_SHIFT 1 /* SAFETY_FACTOR in accecn draft */
/* tp->accecn_fail_mode */
#define TCP_ACCECN_ACE_FAIL_SEND BIT(0)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index ffd9f462370c..b0492f85c4a7 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -709,16 +709,19 @@ static u32 __tcp_accecn_process(struct sock *sk, const struct sk_buff *skb,
u32 delivered_pkts, u32 delivered_bytes,
int flag)
{
+ u32 old_ceb = tcp_sk(sk)->delivered_ecn_bytes[INET_ECN_CE - 1];
const struct tcphdr *th = tcp_hdr(skb);
struct tcp_sock *tp = tcp_sk(sk);
- u32 delta, safe_delta;
+ u32 delta, safe_delta, d_ceb;
+ bool opt_deltas_valid;
u32 corrected_ace;
/* Reordered ACK or uncertain due to lack of data to send and ts */
if (!(flag & (FLAG_FORWARD_PROGRESS | FLAG_TS_PROGRESS)))
return 0;
- tcp_accecn_process_option(tp, skb, delivered_bytes, flag);
+ opt_deltas_valid = tcp_accecn_process_option(tp, skb,
+ delivered_bytes, flag);
if (!(flag & FLAG_SLOWPATH)) {
/* AccECN counter might overflow on large ACKs */
@@ -741,6 +744,17 @@ static u32 __tcp_accecn_process(struct sock *sk, const struct sk_buff *skb,
safe_delta = delivered_pkts -
((delivered_pkts - delta) & TCP_ACCECN_CEP_ACE_MASK);
+ if (opt_deltas_valid) {
+ d_ceb = tp->delivered_ecn_bytes[INET_ECN_CE - 1] - old_ceb;
+ if (!d_ceb)
+ return delta;
+ if (d_ceb > delta * tp->mss_cache)
+ return safe_delta;
+ if (d_ceb <
+ safe_delta * tp->mss_cache >> TCP_ACCECN_SAFETY_SHIFT)
+ return delta;
+ }
+
return safe_delta;
}
--
2.34.1
