diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2023-11-02 14:05:48 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-11-06 08:59:54 +0000 |
| commit | 0a8e987dcc13244b5a5bc90cb1b184f813104d87 (patch) | |
| tree | 013e6e5ce99877c4f5d47011ea1e84c738098ce8 /net/ipv4 | |
| parent | 3423ca23e08bf285a324237abe88e7e7d9becfe6 (diff) | |
tcp: Fix SYN option room calculation for TCP-AO.
When building SYN packet in tcp_syn_options(), MSS, TS, WS, and
SACKPERM are used without checking the remaining bytes in the
options area.
To keep that logic as is, we limit the TCP-AO MAC length in
tcp_ao_parse_crypto(). Currently, the limit is calculated as below.
MAX_TCP_OPTION_SPACE - TCPOLEN_TSTAMP_ALIGNED
- TCPOLEN_WSCALE_ALIGNED
- TCPOLEN_SACKPERM_ALIGNED
This looks confusing as (1) we pack SACKPERM into the leading
2-bytes of the aligned 12-bytes of TS and (2) TCPOLEN_MSS_ALIGNED
is not used. Fortunately, the calculated limit is not wrong as
TCPOLEN_SACKPERM_ALIGNED and TCPOLEN_MSS_ALIGNED are the same value.
However, we should use the proper constant in the formula.
MAX_TCP_OPTION_SPACE - TCPOLEN_MSS_ALIGNED
- TCPOLEN_TSTAMP_ALIGNED
- TCPOLEN_WSCALE_ALIGNED
Fixes: 4954f17ddefc ("net/tcp: Introduce TCP_AO setsockopt()s")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_ao.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c index ef5472ed6158..7696417d0640 100644 --- a/net/ipv4/tcp_ao.c +++ b/net/ipv4/tcp_ao.c @@ -1315,7 +1315,8 @@ static int tcp_ao_parse_crypto(struct tcp_ao_add *cmd, struct tcp_ao_key *key) key->maclen = cmd->maclen ?: 12; /* 12 is the default in RFC5925 */ /* Check: maclen + tcp-ao header <= (MAX_TCP_OPTION_SPACE - mss - * - tstamp - wscale - sackperm), + * - tstamp (including sackperm) + * - wscale), * see tcp_syn_options(), tcp_synack_options(), commit 33ad798c924b. * * In order to allow D-SACK with TCP-AO, the header size should be: @@ -1342,9 +1343,9 @@ static int tcp_ao_parse_crypto(struct tcp_ao_add *cmd, struct tcp_ao_key *key) * large to leave sufficient option space. */ syn_tcp_option_space = MAX_TCP_OPTION_SPACE; + syn_tcp_option_space -= TCPOLEN_MSS_ALIGNED; syn_tcp_option_space -= TCPOLEN_TSTAMP_ALIGNED; syn_tcp_option_space -= TCPOLEN_WSCALE_ALIGNED; - syn_tcp_option_space -= TCPOLEN_SACKPERM_ALIGNED; if (tcp_ao_len(key) > syn_tcp_option_space) { err = -EMSGSIZE; goto err_kfree; |