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| author | Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> | 2007-10-01 15:28:17 -0700 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-10-10 16:53:59 -0700 |
| commit | 0e835331e3111e5a92eb3a852405ea71ca8fff97 (patch) | |
| tree | e7c1445866cf4ed306ffd39e1fd520f2b761566a /net | |
| parent | 95eacd27e2a0924f1435654c06712cee6be099ad (diff) | |
| download | linux-0e835331e3111e5a92eb3a852405ea71ca8fff97.tar.bz2 | |
[TCP]: Update comment of SACK block validator
Just came across what RFC2018 states about generation of valid
SACK blocks in case of reneging. Alter comment a bit to point
out clearly.
IMHO, there isn't any reason to change code because the
validation is there for a purpose (counters will inform user
about decision TCP made if this case ever surfaces).
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 904289d2b6bb..c1339d88bbf3 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1027,8 +1027,15 @@ static void tcp_update_reordering(struct sock *sk, const int metric, * SACK block range validation checks that the received SACK block fits to * the expected sequence limits, i.e., it is between SND.UNA and SND.NXT. * Note that SND.UNA is not included to the range though being valid because - * it means that the receiver is rather inconsistent with itself (reports - * SACK reneging when it should advance SND.UNA). + * it means that the receiver is rather inconsistent with itself reporting + * SACK reneging when it should advance SND.UNA. Such SACK block this is + * perfectly valid, however, in light of RFC2018 which explicitly states + * that "SACK block MUST reflect the newest segment. Even if the newest + * segment is going to be discarded ...", not that it looks very clever + * in case of head skb. Due to potentional receiver driven attacks, we + * choose to avoid immediate execution of a walk in write queue due to + * reneging and defer head skb's loss recovery to standard loss recovery + * procedure that will eventually trigger (nothing forbids us doing this). * * Implements also blockage to start_seq wrap-around. Problem lies in the * fact that though start_seq (s) is before end_seq (i.e., not reversed), |