[PATCH 03/10] netfilter: meta: add PRANDOM support
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2016-03-08 10:00:43
Also in:
netfilter-devel
Subsystem:
library code, netfilter, networking [general], the rest · Maintainers:
Andrew Morton, Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Florian Westphal <fw@strlen.de>
Can be used to randomly match packets e.g. for statistic traffic sampling.
See commit 3ad0040573b0c00f8848
("bpf: split state from prandom_u32() and consolidate {c, e}BPF prngs")
for more info why this doesn't use prandom_u32 directly.
Unlike bpf nft_meta can be built as a module, so add an EXPORT_SYMBOL
for prandom_seed_full_state too.
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
include/uapi/linux/netfilter/nf_tables.h | 2 ++
lib/random32.c | 1 +
net/netfilter/nft_meta.c | 11 +++++++++++
3 files changed, 14 insertions(+)
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index be41ffc..b19be0a 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h@@ -681,6 +681,7 @@ enum nft_exthdr_attributes { * @NFT_META_IIFGROUP: packet input interface group * @NFT_META_OIFGROUP: packet output interface group * @NFT_META_CGROUP: socket control group (skb->sk->sk_classid) + * @NFT_META_PRANDOM: a 32bit pseudo-random number */ enum nft_meta_keys { NFT_META_LEN,
@@ -707,6 +708,7 @@ enum nft_meta_keys { NFT_META_IIFGROUP, NFT_META_OIFGROUP, NFT_META_CGROUP, + NFT_META_PRANDOM, }; /**
diff --git a/lib/random32.c b/lib/random32.c
index 1211191..510d1ce 100644
--- a/lib/random32.c
+++ b/lib/random32.c@@ -255,6 +255,7 @@ void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state) prandom_warmup(state); } } +EXPORT_SYMBOL(prandom_seed_full_state); /* * Generate better values after random number generator
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index fe885bf..16c50b0 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c@@ -28,6 +28,8 @@ #include <uapi/linux/netfilter_bridge.h> /* NF_BR_PRE_ROUTING */ +static DEFINE_PER_CPU(struct rnd_state, nft_prandom_state); + void nft_meta_get_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt)
@@ -181,6 +183,11 @@ void nft_meta_get_eval(const struct nft_expr *expr, *dest = sock_cgroup_classid(&sk->sk_cgrp_data); break; #endif + case NFT_META_PRANDOM: { + struct rnd_state *state = this_cpu_ptr(&nft_prandom_state); + *dest = prandom_u32_state(state); + break; + } default: WARN_ON(1); goto err;
@@ -277,6 +284,10 @@ int nft_meta_get_init(const struct nft_ctx *ctx, case NFT_META_OIFNAME: len = IFNAMSIZ; break; + case NFT_META_PRANDOM: + prandom_init_once(&nft_prandom_state); + len = sizeof(u32); + break; default: return -EOPNOTSUPP; }
--
2.1.4