From 29421198c3a860092e27c2ad8499dfe603398817 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Sat, 26 Mar 2016 16:32:57 +0800 Subject: [PATCH] netfilter: ipv4: fix NULL dereference Commit fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob") use sock_net(skb->sk) to get the net namespace, but we can't assume that sk_buff->sk is always exist, so when it is NULL, oops will happen. Signed-off-by: Liping Zhang Reviewed-by: Nikolay Borisov Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/nft_reject_bridge.c | 20 ++++----- net/ipv4/netfilter/ipt_SYNPROXY.c | 54 ++++++++++++------------ 2 files changed, 38 insertions(+), 36 deletions(-) diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c index adc8d7221dbb..77f7e7a9ebe1 100644 --- a/net/bridge/netfilter/nft_reject_bridge.c +++ b/net/bridge/netfilter/nft_reject_bridge.c @@ -40,7 +40,8 @@ static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb, /* We cannot use oldskb->dev, it can be either bridge device (NF_BRIDGE INPUT) * or the bridge port (NF_BRIDGE PREROUTING). */ -static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb, +static void nft_reject_br_send_v4_tcp_reset(struct net *net, + struct sk_buff *oldskb, const struct net_device *dev, int hook) { @@ -48,7 +49,6 @@ static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb, struct iphdr *niph; const struct tcphdr *oth; struct tcphdr _oth; - struct net *net = sock_net(oldskb->sk); if (!nft_bridge_iphdr_validate(oldskb)) return; @@ -75,7 +75,8 @@ static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb, br_deliver(br_port_get_rcu(dev), nskb); } -static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb, +static void nft_reject_br_send_v4_unreach(struct net *net, + struct sk_buff *oldskb, const struct net_device *dev, int hook, u8 code) { @@ -86,7 +87,6 @@ static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb, void *payload; __wsum csum; u8 proto; - struct net *net = sock_net(oldskb->sk); if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb)) return; @@ -273,17 +273,17 @@ static void nft_reject_bridge_eval(const struct nft_expr *expr, case htons(ETH_P_IP): switch (priv->type) { case NFT_REJECT_ICMP_UNREACH: - nft_reject_br_send_v4_unreach(pkt->skb, pkt->in, - pkt->hook, + nft_reject_br_send_v4_unreach(pkt->net, pkt->skb, + pkt->in, pkt->hook, priv->icmp_code); break; case NFT_REJECT_TCP_RST: - nft_reject_br_send_v4_tcp_reset(pkt->skb, pkt->in, - pkt->hook); + nft_reject_br_send_v4_tcp_reset(pkt->net, pkt->skb, + pkt->in, pkt->hook); break; case NFT_REJECT_ICMPX_UNREACH: - nft_reject_br_send_v4_unreach(pkt->skb, pkt->in, - pkt->hook, + nft_reject_br_send_v4_unreach(pkt->net, pkt->skb, + pkt->in, pkt->hook, nft_reject_icmp_code(priv->icmp_code)); break; } diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c index 7b8fbb352877..db5b87509446 100644 --- a/net/ipv4/netfilter/ipt_SYNPROXY.c +++ b/net/ipv4/netfilter/ipt_SYNPROXY.c @@ -18,10 +18,10 @@ #include static struct iphdr * -synproxy_build_ip(struct sk_buff *skb, __be32 saddr, __be32 daddr) +synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr, + __be32 daddr) { struct iphdr *iph; - struct net *net = sock_net(skb->sk); skb_reset_network_header(skb); iph = (struct iphdr *)skb_put(skb, sizeof(*iph)); @@ -40,14 +40,12 @@ synproxy_build_ip(struct sk_buff *skb, __be32 saddr, __be32 daddr) } static void -synproxy_send_tcp(const struct synproxy_net *snet, +synproxy_send_tcp(struct net *net, const struct sk_buff *skb, struct sk_buff *nskb, struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo, struct iphdr *niph, struct tcphdr *nth, unsigned int tcp_hdr_size) { - struct net *net = nf_ct_net(snet->tmpl); - nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0); nskb->ip_summed = CHECKSUM_PARTIAL; nskb->csum_start = (unsigned char *)nth - nskb->head; @@ -72,7 +70,7 @@ free_nskb: } static void -synproxy_send_client_synack(const struct synproxy_net *snet, +synproxy_send_client_synack(struct net *net, const struct sk_buff *skb, const struct tcphdr *th, const struct synproxy_options *opts) { @@ -91,7 +89,7 @@ synproxy_send_client_synack(const struct synproxy_net *snet, return; skb_reserve(nskb, MAX_TCP_HEADER); - niph = synproxy_build_ip(nskb, iph->daddr, iph->saddr); + niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); skb_reset_transport_header(nskb); nth = (struct tcphdr *)skb_put(nskb, tcp_hdr_size); @@ -109,15 +107,16 @@ synproxy_send_client_synack(const struct synproxy_net *snet, synproxy_build_options(nth, opts); - synproxy_send_tcp(snet, skb, nskb, skb->nfct, IP_CT_ESTABLISHED_REPLY, + synproxy_send_tcp(net, skb, nskb, skb->nfct, IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); } static void -synproxy_send_server_syn(const struct synproxy_net *snet, +synproxy_send_server_syn(struct net *net, const struct sk_buff *skb, const struct tcphdr *th, const struct synproxy_options *opts, u32 recv_seq) { + struct synproxy_net *snet = synproxy_pernet(net); struct sk_buff *nskb; struct iphdr *iph, *niph; struct tcphdr *nth; @@ -132,7 +131,7 @@ synproxy_send_server_syn(const struct synproxy_net *snet, return; skb_reserve(nskb, MAX_TCP_HEADER); - niph = synproxy_build_ip(nskb, iph->saddr, iph->daddr); + niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); skb_reset_transport_header(nskb); nth = (struct tcphdr *)skb_put(nskb, tcp_hdr_size); @@ -153,12 +152,12 @@ synproxy_send_server_syn(const struct synproxy_net *snet, synproxy_build_options(nth, opts); - synproxy_send_tcp(snet, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW, + synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW, niph, nth, tcp_hdr_size); } static void -synproxy_send_server_ack(const struct synproxy_net *snet, +synproxy_send_server_ack(struct net *net, const struct ip_ct_tcp *state, const struct sk_buff *skb, const struct tcphdr *th, const struct synproxy_options *opts) @@ -177,7 +176,7 @@ synproxy_send_server_ack(const struct synproxy_net *snet, return; skb_reserve(nskb, MAX_TCP_HEADER); - niph = synproxy_build_ip(nskb, iph->daddr, iph->saddr); + niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); skb_reset_transport_header(nskb); nth = (struct tcphdr *)skb_put(nskb, tcp_hdr_size); @@ -193,11 +192,11 @@ synproxy_send_server_ack(const struct synproxy_net *snet, synproxy_build_options(nth, opts); - synproxy_send_tcp(snet, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); + synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); } static void -synproxy_send_client_ack(const struct synproxy_net *snet, +synproxy_send_client_ack(struct net *net, const struct sk_buff *skb, const struct tcphdr *th, const struct synproxy_options *opts) { @@ -215,7 +214,7 @@ synproxy_send_client_ack(const struct synproxy_net *snet, return; skb_reserve(nskb, MAX_TCP_HEADER); - niph = synproxy_build_ip(nskb, iph->saddr, iph->daddr); + niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); skb_reset_transport_header(nskb); nth = (struct tcphdr *)skb_put(nskb, tcp_hdr_size); @@ -231,15 +230,16 @@ synproxy_send_client_ack(const struct synproxy_net *snet, synproxy_build_options(nth, opts); - synproxy_send_tcp(snet, skb, nskb, skb->nfct, IP_CT_ESTABLISHED_REPLY, + synproxy_send_tcp(net, skb, nskb, skb->nfct, IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); } static bool -synproxy_recv_client_ack(const struct synproxy_net *snet, +synproxy_recv_client_ack(struct net *net, const struct sk_buff *skb, const struct tcphdr *th, struct synproxy_options *opts, u32 recv_seq) { + struct synproxy_net *snet = synproxy_pernet(net); int mss; mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1); @@ -255,7 +255,7 @@ synproxy_recv_client_ack(const struct synproxy_net *snet, if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP) synproxy_check_timestamp_cookie(opts); - synproxy_send_server_syn(snet, skb, th, opts, recv_seq); + synproxy_send_server_syn(net, skb, th, opts, recv_seq); return true; } @@ -263,7 +263,8 @@ static unsigned int synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par) { const struct xt_synproxy_info *info = par->targinfo; - struct synproxy_net *snet = synproxy_pernet(par->net); + struct net *net = par->net; + struct synproxy_net *snet = synproxy_pernet(net); struct synproxy_options opts = {}; struct tcphdr *th, _th; @@ -292,12 +293,12 @@ synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par) XT_SYNPROXY_OPT_SACK_PERM | XT_SYNPROXY_OPT_ECN); - synproxy_send_client_synack(snet, skb, th, &opts); + synproxy_send_client_synack(net, skb, th, &opts); return NF_DROP; } else if (th->ack && !(th->fin || th->rst || th->syn)) { /* ACK from client */ - synproxy_recv_client_ack(snet, skb, th, &opts, ntohl(th->seq)); + synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq)); return NF_DROP; } @@ -308,7 +309,8 @@ static unsigned int ipv4_synproxy_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *nhs) { - struct synproxy_net *snet = synproxy_pernet(nhs->net); + struct net *net = nhs->net; + struct synproxy_net *snet = synproxy_pernet(net); enum ip_conntrack_info ctinfo; struct nf_conn *ct; struct nf_conn_synproxy *synproxy; @@ -365,7 +367,7 @@ static unsigned int ipv4_synproxy_hook(void *priv, * therefore we need to add 1 to make the SYN sequence * number match the one of first SYN. */ - if (synproxy_recv_client_ack(snet, skb, th, &opts, + if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq) + 1)) this_cpu_inc(snet->stats->cookie_retrans); @@ -391,12 +393,12 @@ static unsigned int ipv4_synproxy_hook(void *priv, XT_SYNPROXY_OPT_SACK_PERM); swap(opts.tsval, opts.tsecr); - synproxy_send_server_ack(snet, state, skb, th, &opts); + synproxy_send_server_ack(net, state, skb, th, &opts); nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); swap(opts.tsval, opts.tsecr); - synproxy_send_client_ack(snet, skb, th, &opts); + synproxy_send_client_ack(net, skb, th, &opts); consume_skb(skb); return NF_STOLEN; -- 2.20.1