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authorJeffrey Altman <jaltman@auristor.com>2019-04-12 16:34:16 +0100
committerDavid S. Miller <davem@davemloft.net>2019-04-12 16:57:23 -0700
commit1a2391c30c0b9d041bc340f68df81d49c53546cc (patch)
treeadec0da77205b01e590914e28aca0930926f9949 /net/rxrpc
parent39ce67557568962fa9d1593741f76c4cc6762469 (diff)
downloadlinux-stericsson-1a2391c30c0b9d041bc340f68df81d49c53546cc.tar.gz
rxrpc: Fix detection of out of order acks
The rxrpc packet serial number cannot be safely used to compute out of order ack packets for several reasons: 1. The allocation of serial numbers cannot be assumed to imply the order by which acks are populated and transmitted. In some rxrpc implementations, delayed acks and ping acks are transmitted asynchronously to the receipt of data packets and so may be transmitted out of order. As a result, they can race with idle acks. 2. Serial numbers are allocated by the rxrpc connection and not the call and as such may wrap independently if multiple channels are in use. In any case, what matters is whether the ack packet provides new information relating to the bounds of the window (the firstPacket and previousPacket in the ACK data). Fix this by discarding packets that appear to wind back the window bounds rather than on serial number procession. Fixes: 298bc15b2079 ("rxrpc: Only take the rwind and mtu values from latest ACK") Signed-off-by: Jeffrey Altman <jaltman@auristor.com> Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Marc Dionne <marc.dionne@auristor.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rxrpc')
-rw-r--r--net/rxrpc/ar-internal.h1
-rw-r--r--net/rxrpc/input.c18
2 files changed, 13 insertions, 6 deletions
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 4b1a534d290a..062ca9dc29b8 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -654,6 +654,7 @@ struct rxrpc_call {
u8 ackr_reason; /* reason to ACK */
u16 ackr_skew; /* skew on packet being ACK'd */
rxrpc_serial_t ackr_serial; /* serial of packet being ACK'd */
+ rxrpc_serial_t ackr_first_seq; /* first sequence number received */
rxrpc_seq_t ackr_prev_seq; /* previous sequence number received */
rxrpc_seq_t ackr_consumed; /* Highest packet shown consumed */
rxrpc_seq_t ackr_seen; /* Highest packet shown seen */
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 9128aa0e40aa..4c6f9d0a00e7 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -837,7 +837,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
u8 acks[RXRPC_MAXACKS];
} buf;
rxrpc_serial_t acked_serial;
- rxrpc_seq_t first_soft_ack, hard_ack;
+ rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
int nr_acks, offset, ioffset;
_enter("");
@@ -851,13 +851,14 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
acked_serial = ntohl(buf.ack.serial);
first_soft_ack = ntohl(buf.ack.firstPacket);
+ prev_pkt = ntohl(buf.ack.previousPacket);
hard_ack = first_soft_ack - 1;
nr_acks = buf.ack.nAcks;
summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
buf.ack.reason : RXRPC_ACK__INVALID);
trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
- first_soft_ack, ntohl(buf.ack.previousPacket),
+ first_soft_ack, prev_pkt,
summary.ack_reason, nr_acks);
if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
@@ -878,8 +879,9 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
rxrpc_propose_ack_respond_to_ack);
}
- /* Discard any out-of-order or duplicate ACKs. */
- if (before_eq(sp->hdr.serial, call->acks_latest))
+ /* Discard any out-of-order or duplicate ACKs (outside lock). */
+ if (before(first_soft_ack, call->ackr_first_seq) ||
+ before(prev_pkt, call->ackr_prev_seq))
return;
buf.info.rxMTU = 0;
@@ -890,12 +892,16 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
spin_lock(&call->input_lock);
- /* Discard any out-of-order or duplicate ACKs. */
- if (before_eq(sp->hdr.serial, call->acks_latest))
+ /* Discard any out-of-order or duplicate ACKs (inside lock). */
+ if (before(first_soft_ack, call->ackr_first_seq) ||
+ before(prev_pkt, call->ackr_prev_seq))
goto out;
call->acks_latest_ts = skb->tstamp;
call->acks_latest = sp->hdr.serial;
+ call->ackr_first_seq = first_soft_ack;
+ call->ackr_prev_seq = prev_pkt;
+
/* Parse rwind and mtu sizes if provided. */
if (buf.info.rxMTU)
rxrpc_input_ackinfo(call, skb, &buf.info);