From 1a893b44de4528887e7dabcdce7151ca2a8ee238 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Wed, 30 May 2018 11:06:22 +0200 Subject: [PATCH] netfilter: nf_tables: Add audit support to log statement This extends log statement to support the behaviour achieved with AUDIT target in iptables. Audit logging is enabled via a pseudo log level 8. In this case any other settings like log prefix are ignored since audit log format is fixed. Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/nf_tables.h | 5 ++ net/netfilter/nft_log.c | 92 +++++++++++++++++++++++- 2 files changed, 96 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 3d46c82a5ebd..5c7eb9b9f6d6 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -1080,6 +1080,11 @@ enum nft_log_attributes { }; #define NFTA_LOG_MAX (__NFTA_LOG_MAX - 1) +/** + * LOGLEVEL_AUDIT - a pseudo log level enabling audit logging + */ +#define LOGLEVEL_AUDIT 8 + /** * enum nft_queue_attributes - nf_tables queue expression netlink attributes * diff --git a/net/netfilter/nft_log.c b/net/netfilter/nft_log.c index a27be36dc0af..7eef1cffbf1b 100644 --- a/net/netfilter/nft_log.c +++ b/net/netfilter/nft_log.c @@ -9,12 +9,15 @@ * Development of this code funded by Astaro AG (http://www.astaro.com/) */ +#include #include #include #include #include #include #include +#include +#include #include #include #include @@ -26,12 +29,93 @@ struct nft_log { char *prefix; }; +static bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb) +{ + struct iphdr _iph; + const struct iphdr *ih; + + ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_iph), &_iph); + if (!ih) + return false; + + audit_log_format(ab, " saddr=%pI4 daddr=%pI4 proto=%hhu", + &ih->saddr, &ih->daddr, ih->protocol); + + return true; +} + +static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb) +{ + struct ipv6hdr _ip6h; + const struct ipv6hdr *ih; + u8 nexthdr; + __be16 frag_off; + + ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h); + if (!ih) + return false; + + nexthdr = ih->nexthdr; + ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h), &nexthdr, &frag_off); + + audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu", + &ih->saddr, &ih->daddr, nexthdr); + + return true; +} + +static void nft_log_eval_audit(const struct nft_pktinfo *pkt) +{ + struct sk_buff *skb = pkt->skb; + struct audit_buffer *ab; + int fam = -1; + + if (!audit_enabled) + return; + + ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT); + if (!ab) + return; + + audit_log_format(ab, "mark=%#x", skb->mark); + + switch (nft_pf(pkt)) { + case NFPROTO_BRIDGE: + switch (eth_hdr(skb)->h_proto) { + case htons(ETH_P_IP): + fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1; + break; + case htons(ETH_P_IPV6): + fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1; + break; + } + break; + case NFPROTO_IPV4: + fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1; + break; + case NFPROTO_IPV6: + fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1; + break; + } + + if (fam == -1) + audit_log_format(ab, " saddr=? daddr=? proto=-1"); + + audit_log_end(ab); +} + static void nft_log_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) { const struct nft_log *priv = nft_expr_priv(expr); + if (priv->loginfo.type == NF_LOG_TYPE_LOG && + priv->loginfo.u.log.level == LOGLEVEL_AUDIT) { + nft_log_eval_audit(pkt); + return; + } + nf_log_packet(nft_net(pkt), nft_pf(pkt), nft_hook(pkt), pkt->skb, nft_in(pkt), nft_out(pkt), &priv->loginfo, "%s", priv->prefix); @@ -84,7 +168,7 @@ static int nft_log_init(const struct nft_ctx *ctx, } else { li->u.log.level = LOGLEVEL_WARNING; } - if (li->u.log.level > LOGLEVEL_DEBUG) { + if (li->u.log.level > LOGLEVEL_AUDIT) { err = -EINVAL; goto err1; } @@ -112,6 +196,9 @@ static int nft_log_init(const struct nft_ctx *ctx, break; } + if (li->u.log.level == LOGLEVEL_AUDIT) + return 0; + err = nf_logger_find_get(ctx->family, li->type); if (err < 0) goto err1; @@ -133,6 +220,9 @@ static void nft_log_destroy(const struct nft_ctx *ctx, if (priv->prefix != nft_log_null_prefix) kfree(priv->prefix); + if (li->u.log.level == LOGLEVEL_AUDIT) + return; + nf_logger_put(ctx->family, li->type); } -- 2.20.1