diff options
| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2006-11-10 02:13:56 -0200 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2006-12-02 21:21:53 -0800 |
| commit | 60361be1be7854cbffb6dc268d1bc094da33431c (patch) | |
| tree | 58109e5c2020acfafd3c3e140620b7a93f0384ac | |
| parent | 931731123a103cfb3f70ac4b7abfc71d94ba1f03 (diff) | |
[DCCP]: set safe upper bound for option length
This is a re-send from
http://www.mail-archive.com/dccp@vger.kernel.org/msg00553.html
It is the same patch as before, but I have built in Arnaldo's suggestions
pointed out in that posting.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
| -rw-r--r-- | net/dccp/dccp.h | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h index 272e8584564e..9f00dd807e04 100644 --- a/net/dccp/dccp.h +++ b/net/dccp/dccp.h @@ -40,12 +40,18 @@ extern void dccp_tw_deschedule(struct inet_timewait_sock *tw); extern void dccp_time_wait(struct sock *sk, int state, int timeo); -/* FIXME: Right size this */ -#define DCCP_MAX_OPT_LEN 128 - -#define DCCP_MAX_PACKET_HDR 32 - -#define MAX_DCCP_HEADER (DCCP_MAX_PACKET_HDR + DCCP_MAX_OPT_LEN + MAX_HEADER) +/* + * Set safe upper bounds for header and option length. Since Data Offset is 8 + * bits (RFC 4340, sec. 5.1), the total header length can never be more than + * 4 * 255 = 1020 bytes. The largest possible header length is 28 bytes (X=1): + * - DCCP-Response with ACK Subheader and 4 bytes of Service code OR + * - DCCP-Reset with ACK Subheader and 4 bytes of Reset Code fields + * Hence a safe upper bound for the maximum option length is 1020-28 = 992 + */ +#define MAX_DCCP_SPECIFIC_HEADER (255 * sizeof(int)) +#define DCCP_MAX_PACKET_HDR 28 +#define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR) +#define MAX_DCCP_HEADER (MAX_DCCP_SPECIFIC_HEADER + MAX_HEADER) #define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT * state, about 60 seconds */ |