From fc910a27839584209726537698b596576940add4 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sun, 25 Mar 2007 20:27:59 -0700 Subject: [PATCH] [NETLINK]: Limit NLMSG_GOODSIZE to 8K. Signed-off-by: David S. Miller --- include/linux/netlink.h | 11 +++++++++-- include/linux/skbuff.h | 8 +++++--- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 2a20f488ac..a9d3ad5bc8 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -171,9 +171,16 @@ int netlink_sendskb(struct sock *sk, struct sk_buff *skb, int protocol); /* * skb should fit one page. This choice is good for headerless malloc. + * But we should limit to 8K so that userspace does not have to + * use enormous buffer sizes on recvmsg() calls just to avoid + * MSG_TRUNC when PAGE_SIZE is very large. */ -#define NLMSG_GOODORDER 0 -#define NLMSG_GOODSIZE (SKB_MAX_ORDER(0, NLMSG_GOODORDER)) +#if PAGE_SIZE < 8192UL +#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE) +#else +#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL) +#endif + #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index f9441b5f8d..30089adb2e 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -39,9 +39,11 @@ #define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \ ~(SMP_CACHE_BYTES - 1)) -#define SKB_MAX_ORDER(X, ORDER) (((PAGE_SIZE << (ORDER)) - (X) - \ - sizeof(struct skb_shared_info)) & \ - ~(SMP_CACHE_BYTES - 1)) +#define SKB_WITH_OVERHEAD(X) \ + (((X) - sizeof(struct skb_shared_info)) & \ + ~(SMP_CACHE_BYTES - 1)) +#define SKB_MAX_ORDER(X, ORDER) \ + SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X)) #define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0)) #define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2)) -- 2.39.5