sctp: introduce sctp_mtu_payload
When given a MTU, this function calculates how much payload we can carry
on it. Without a MTU, it calculates the amount of header overhead we
have.
So that when we have extra overhead, like the one added for IP options
on SELinux patches, it is easier to handle it.
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index eeec81d..b9d14f5 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -3234,11 +3234,8 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned
if (val) {
int min_len, max_len;
- min_len = SCTP_DEFAULT_MINSEGMENT - af->net_header_len;
- min_len -= af->ip_options_len(sk);
- min_len -= sizeof(struct sctphdr) +
- sizeof(struct sctp_data_chunk);
-
+ min_len = sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT,
+ sizeof(struct sctp_data_chunk));
max_len = SCTP_MAX_CHUNK_LEN - sizeof(struct sctp_data_chunk);
if (val < min_len || val > max_len)