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authorFlorian Westphal <fw@strlen.de>2016-02-16 17:24:08 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2016-02-29 13:55:59 +0100
commitb07edbe1cf3dae9ba81f24888e2f2a9dbe778918 (patch)
treeed0bb89d4e43f6eea804b4d1cbad01050dae3b30 /net/netfilter/nft_meta.c
parentf12d33f4d83c6837d176e1aef337914089c77957 (diff)
netfilter: meta: add PRANDOM support
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>
Diffstat (limited to 'net/netfilter/nft_meta.c')
-rw-r--r--net/netfilter/nft_meta.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index fe885bf271c5..16c50b0dd426 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;
}