From 03f0843bdbcd5a00a9b8541dfec1853a1228c9dc Mon Sep 17 00:00:00 2001 From: Lawrence Stewart Date: Tue, 1 Feb 2011 13:32:27 +0000 Subject: [PATCH] Algorithm modules can define their own private congestion signal types in the top 8 bits of the 32 bit signal bit field space for internal use. These private signals should not be leaked outside of a module. Given that many algorithm modules use the NewReno hook functions to simplify their implementation, the obvious place such a leak would show up is in the NewReno cong_signal hook function. - Show the full number of significant bits in the signal type definitions in . - Add a bitmask to simplify figuring out if a given signal is in the private or public bit range. - Add a sanity check in newreno_cong_signal() to ensure private signals are not being leaked into the hook function. Sponsored by: FreeBSD Foundation Discussed with: David Hayes MFC after: 1 week X-MFC with: r215166 --- sys/netinet/cc.h | 10 ++++++---- sys/netinet/cc/cc_newreno.c | 4 ++++ 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/sys/netinet/cc.h b/sys/netinet/cc.h index aaa1d67ae1b2..332e51cdbd16 100644 --- a/sys/netinet/cc.h +++ b/sys/netinet/cc.h @@ -101,10 +101,12 @@ struct cc_var { * bits (0x01000000 - 0x80000000) are reserved for CC algos to declare their own * congestion signal types. */ -#define CC_ECN 0x000001/* ECN marked packet received. */ -#define CC_RTO 0x000002/* RTO fired. */ -#define CC_RTO_ERR 0x000004/* RTO fired in error. */ -#define CC_NDUPACK 0x000008/* Threshold of dupack's reached. */ +#define CC_ECN 0x00000001 /* ECN marked packet received. */ +#define CC_RTO 0x00000002 /* RTO fired. */ +#define CC_RTO_ERR 0x00000004 /* RTO fired in error. */ +#define CC_NDUPACK 0x00000008 /* Threshold of dupack's reached. */ + +#define CC_SIGPRIVMASK 0xFF000000 /* Mask to check if sig is private. */ /* * Structure to hold data and function pointers that together represent a diff --git a/sys/netinet/cc/cc_newreno.c b/sys/netinet/cc/cc_newreno.c index c09554093e6a..f26553ddaefb 100644 --- a/sys/netinet/cc/cc_newreno.c +++ b/sys/netinet/cc/cc_newreno.c @@ -182,6 +182,10 @@ newreno_cong_signal(struct cc_var *ccv, uint32_t type) { u_int win; + /* Catch algos which mistakenly leak private signal types. */ + KASSERT((type & CC_SIGPRIVMASK) == 0, + ("%s: congestion signal type 0x%08x is private\n", __func__, type)); + win = max(CCV(ccv, snd_cwnd) / 2 / CCV(ccv, t_maxseg), 2) * CCV(ccv, t_maxseg);