From fdb694a01f1fcd30fd16d8aa290c34699fe98a17 Mon Sep 17 00:00:00 2001 From: Krishna Kumar Date: Thu, 24 May 2012 03:56:44 +0000 Subject: [PATCH] netfilter: Add fail-open support Implement a new "fail-open" mode where packets are not dropped upon queue-full condition. This mode can be enabled/disabled per queue using netlink NFQA_CFG_FLAGS & NFQA_CFG_MASK attributes. Signed-off-by: Krishna Kumar Signed-off-by: Vivek Kashyap Signed-off-by: Sridhar Samudrala --- include/linux/netfilter/nfnetlink_queue.h | 5 ++++ net/netfilter/nfnetlink_queue.c | 40 ++++++++++++++++++++++++++++--- 2 files changed, 42 insertions(+), 3 deletions(-) diff --git a/include/linux/netfilter/nfnetlink_queue.h b/include/linux/netfilter/nfnetlink_queue.h index 24b32e6..a6c1dda 100644 --- a/include/linux/netfilter/nfnetlink_queue.h +++ b/include/linux/netfilter/nfnetlink_queue.h @@ -84,8 +84,13 @@ enum nfqnl_attr_config { NFQA_CFG_CMD, /* nfqnl_msg_config_cmd */ NFQA_CFG_PARAMS, /* nfqnl_msg_config_params */ NFQA_CFG_QUEUE_MAXLEN, /* __u32 */ + NFQA_CFG_MASK, /* identify which flags to change */ + NFQA_CFG_FLAGS, /* value of these flags (__u32) */ __NFQA_CFG_MAX }; #define NFQA_CFG_MAX (__NFQA_CFG_MAX-1) +/* Flags for NFQA_CFG_FLAGS */ +#define NFQA_CFG_F_FAIL_OPEN (1 << 0) + #endif /* _NFNETLINK_QUEUE_H */ diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index 4162437..630da3d 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -52,6 +52,7 @@ struct nfqnl_instance { u_int16_t queue_num; /* number of this queue */ u_int8_t copy_mode; + u_int32_t flags; /* Set using NFQA_CFG_FLAGS */ /* * Following fields are dirtied for each queued packet, * keep them in same cache line if possible. @@ -406,6 +407,7 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum) struct nfqnl_instance *queue; int err = -ENOBUFS; __be32 *packet_id_ptr; + int failopen = 0; /* rcu_read_lock()ed by nf_hook_slow() */ queue = instance_lookup(queuenum); @@ -431,9 +433,14 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum) goto err_out_free_nskb; } if (queue->queue_total >= queue->queue_maxlen) { - queue->queue_dropped++; - net_warn_ratelimited("nf_queue: full at %d entries, dropping packets(s)\n", - queue->queue_total); + if (queue->flags & NFQA_CFG_F_FAIL_OPEN) { + failopen = 1; + err = 0; + } else { + queue->queue_dropped++; + net_warn_ratelimited("nf_queue: full at %d entries, dropping packets(s)\n", + queue->queue_total); + } goto err_out_free_nskb; } entry->id = ++queue->id_sequence; @@ -455,6 +462,8 @@ err_out_free_nskb: kfree_skb(nskb); err_out_unlock: spin_unlock_bh(&queue->lock); + if (failopen) + nf_reinject(entry, NF_ACCEPT); err_out: return err; } @@ -858,6 +867,31 @@ nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb, spin_unlock_bh(&queue->lock); } + if (nfqa[NFQA_CFG_FLAGS]) { + __u32 flags, mask; + + if (!queue) { + ret = -ENODEV; + goto err_out_unlock; + } + + if (!nfqa[NFQA_CFG_MASK]) { + /* A mask is needed to specify which flags are being + * changed. + */ + ret = -EINVAL; + goto err_out_unlock; + } + + flags = ntohl(nla_get_be32(nfqa[NFQA_CFG_FLAGS])); + mask = ntohl(nla_get_be32(nfqa[NFQA_CFG_MASK])); + + spin_lock_bh(&queue->lock); + queue->flags &= ~mask; + queue->flags |= flags & mask; + spin_unlock_bh(&queue->lock); + } + err_out_unlock: rcu_read_unlock(); return ret; -- 2.7.4