From f615df76ed862b7d3927ec5f55b805ca19be29d9 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 18 Jan 2011 15:52:14 +0100 Subject: [PATCH] netfilter: reduce NF_VERDICT_MASK to 0xff NF_VERDICT_MASK is currently 0xffff. This is because the upper 16 bits are used to store errno (for NF_DROP) or the queue number (NF_QUEUE verdict). As there are up to 0xffff different queues available, there is no more room to store additional flags. At the moment there are only 6 different verdicts, i.e. we can reduce NF_VERDICT_MASK to 0xff to allow storing additional flags in the 0xff00 space. NF_VERDICT_BITS would then be reduced to 8, but because the value is exported to userspace, this might cause breakage; e.g.: e.g. 'queuenr = (1 << NF_VERDICT_BITS) | NF_QUEUE' would now break. Thus, remove NF_VERDICT_BITS usage in the kernel and move the old value to the 'userspace compat' section. Signed-off-by: Florian Westphal Signed-off-by: Patrick McHardy --- include/linux/netfilter.h | 20 +++++++++++++++----- net/netfilter/core.c | 4 ++-- net/netfilter/nf_queue.c | 2 +- 3 files changed, 18 insertions(+), 8 deletions(-) diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h index 0ab7ca787b22..78b73cc10216 100644 --- a/include/linux/netfilter.h +++ b/include/linux/netfilter.h @@ -24,16 +24,19 @@ #define NF_MAX_VERDICT NF_STOP /* we overload the higher bits for encoding auxiliary data such as the queue - * number. Not nice, but better than additional function arguments. */ -#define NF_VERDICT_MASK 0x0000ffff -#define NF_VERDICT_BITS 16 + * number or errno values. Not nice, but better than additional function + * arguments. */ +#define NF_VERDICT_MASK 0x000000ff + +/* extra verdict flags have mask 0x0000ff00 */ +/* queue number (NF_QUEUE) or errno (NF_DROP) */ #define NF_VERDICT_QMASK 0xffff0000 #define NF_VERDICT_QBITS 16 -#define NF_QUEUE_NR(x) ((((x) << NF_VERDICT_BITS) & NF_VERDICT_QMASK) | NF_QUEUE) +#define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE) -#define NF_DROP_ERR(x) (((-x) << NF_VERDICT_BITS) | NF_DROP) +#define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP) /* only for userspace compatibility */ #ifndef __KERNEL__ @@ -41,6 +44,9 @@ <= 0x2000 is used for protocol-flags. */ #define NFC_UNKNOWN 0x4000 #define NFC_ALTERED 0x8000 + +/* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */ +#define NF_VERDICT_BITS 16 #endif enum nf_inet_hooks { @@ -72,6 +78,10 @@ union nf_inet_addr { #ifdef __KERNEL__ #ifdef CONFIG_NETFILTER +static inline int NF_DROP_GETERR(int verdict) +{ + return -(verdict >> NF_VERDICT_QBITS); +} static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1, const union nf_inet_addr *a2) diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 0c5b796ef527..4d88e45b978e 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -175,12 +175,12 @@ int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb, ret = 1; } else if ((verdict & NF_VERDICT_MASK) == NF_DROP) { kfree_skb(skb); - ret = -(verdict >> NF_VERDICT_BITS); + ret = NF_DROP_GETERR(verdict); if (ret == 0) ret = -EPERM; } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) { ret = nf_queue(skb, elem, pf, hook, indev, outdev, okfn, - verdict >> NF_VERDICT_BITS); + verdict >> NF_VERDICT_QBITS); if (ret < 0) { if (ret == -ECANCELED) goto next_hook; diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c index 5c4b730a2e68..ce1150d4a3f2 100644 --- a/net/netfilter/nf_queue.c +++ b/net/netfilter/nf_queue.c @@ -299,7 +299,7 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) case NF_QUEUE: err = __nf_queue(skb, elem, entry->pf, entry->hook, entry->indev, entry->outdev, entry->okfn, - verdict >> NF_VERDICT_BITS); + verdict >> NF_VERDICT_QBITS); if (err < 0) { if (err == -ECANCELED) goto next_hook; -- GitLab