From 3d53666b40007b55204ee8890618da79a20c9940 Mon Sep 17 00:00:00 2001 From: Alex Gartrell Date: Mon, 6 Oct 2014 08:46:19 -0700 Subject: ipvs: Avoid null-pointer deref in debug code Use daddr instead of reaching into dest. Reported-by: Dan Carpenter Signed-off-by: Alex Gartrell Signed-off-by: Simon Horman --- net/netfilter/ipvs/ip_vs_xmit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c index 91f17c1eb8a2..437a3663ad03 100644 --- a/net/netfilter/ipvs/ip_vs_xmit.c +++ b/net/netfilter/ipvs/ip_vs_xmit.c @@ -316,7 +316,7 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest, if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode, local))) { IP_VS_DBG_RL("We are crossing local and non-local addresses" - " daddr=%pI4\n", &dest->addr.ip); + " daddr=%pI4\n", &daddr); goto err_put; } @@ -458,7 +458,7 @@ __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest, if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode, local))) { IP_VS_DBG_RL("We are crossing local and non-local addresses" - " daddr=%pI6\n", &dest->addr.in6); + " daddr=%pI6\n", daddr); goto err_put; } -- cgit v1.2.3 From 4d87716cd057bde3f90e304289c1fec88d45a1cc Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sat, 25 Oct 2014 12:25:06 +0200 Subject: netfilter: nf_tables_bridge: update hook_mask to allow {pre,post}routing Fixes: 36d2af5 ("netfilter: nf_tables: allow to filter from prerouting and postrouting") Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/nf_tables_bridge.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/bridge/netfilter/nf_tables_bridge.c b/net/bridge/netfilter/nf_tables_bridge.c index da17a5eab8b4..074c557ab505 100644 --- a/net/bridge/netfilter/nf_tables_bridge.c +++ b/net/bridge/netfilter/nf_tables_bridge.c @@ -75,9 +75,11 @@ static const struct nf_chain_type filter_bridge = { .type = NFT_CHAIN_T_DEFAULT, .family = NFPROTO_BRIDGE, .owner = THIS_MODULE, - .hook_mask = (1 << NF_BR_LOCAL_IN) | + .hook_mask = (1 << NF_BR_PRE_ROUTING) | + (1 << NF_BR_LOCAL_IN) | (1 << NF_BR_FORWARD) | - (1 << NF_BR_LOCAL_OUT), + (1 << NF_BR_LOCAL_OUT) | + (1 << NF_BR_POST_ROUTING), }; static int __init nf_tables_bridge_init(void) -- cgit v1.2.3 From 052b9498eea532deb5de75277a53f6e0623215dc Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sat, 25 Oct 2014 18:24:57 +0200 Subject: netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions That can be reused by the reject bridge expression to build the reject packet. The new functions are: * nf_reject_ip_tcphdr_get(): to sanitize and to obtain the TCP header. * nf_reject_iphdr_put(): to build the IPv4 header. * nf_reject_ip_tcphdr_put(): to build the TCP header. Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/ipv4/nf_reject.h | 10 ++++ net/ipv4/netfilter/nf_reject_ipv4.c | 88 ++++++++++++++++++++++++---------- 2 files changed, 72 insertions(+), 26 deletions(-) diff --git a/include/net/netfilter/ipv4/nf_reject.h b/include/net/netfilter/ipv4/nf_reject.h index e8427193c777..03e928a55229 100644 --- a/include/net/netfilter/ipv4/nf_reject.h +++ b/include/net/netfilter/ipv4/nf_reject.h @@ -1,6 +1,8 @@ #ifndef _IPV4_NF_REJECT_H #define _IPV4_NF_REJECT_H +#include +#include #include static inline void nf_send_unreach(struct sk_buff *skb_in, int code) @@ -10,4 +12,12 @@ static inline void nf_send_unreach(struct sk_buff *skb_in, int code) void nf_send_reset(struct sk_buff *oldskb, int hook); +const struct tcphdr *nf_reject_ip_tcphdr_get(struct sk_buff *oldskb, + struct tcphdr *_oth, int hook); +struct iphdr *nf_reject_iphdr_put(struct sk_buff *nskb, + const struct sk_buff *oldskb, + __be16 protocol, int ttl); +void nf_reject_ip_tcphdr_put(struct sk_buff *nskb, const struct sk_buff *oldskb, + const struct tcphdr *oth); + #endif /* _IPV4_NF_REJECT_H */ diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c index 92b303dbd5fc..1baaa83dfe5c 100644 --- a/net/ipv4/netfilter/nf_reject_ipv4.c +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -12,43 +12,39 @@ #include #include #include +#include -/* Send RST reply */ -void nf_send_reset(struct sk_buff *oldskb, int hook) +const struct tcphdr *nf_reject_ip_tcphdr_get(struct sk_buff *oldskb, + struct tcphdr *_oth, int hook) { - struct sk_buff *nskb; - const struct iphdr *oiph; - struct iphdr *niph; const struct tcphdr *oth; - struct tcphdr _otcph, *tcph; /* IP header checks: fragment. */ if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) - return; + return NULL; oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb), - sizeof(_otcph), &_otcph); + sizeof(struct tcphdr), _oth); if (oth == NULL) - return; + return NULL; /* No RST for RST. */ if (oth->rst) - return; - - if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) - return; + return NULL; /* Check checksum */ if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP)) - return; - oiph = ip_hdr(oldskb); + return NULL; - nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + - LL_MAX_HEADER, GFP_ATOMIC); - if (!nskb) - return; + return oth; +} +EXPORT_SYMBOL_GPL(nf_reject_ip_tcphdr_get); - skb_reserve(nskb, LL_MAX_HEADER); +struct iphdr *nf_reject_iphdr_put(struct sk_buff *nskb, + const struct sk_buff *oldskb, + __be16 protocol, int ttl) +{ + struct iphdr *niph, *oiph = ip_hdr(oldskb); skb_reset_network_header(nskb); niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr)); @@ -57,10 +53,23 @@ void nf_send_reset(struct sk_buff *oldskb, int hook) niph->tos = 0; niph->id = 0; niph->frag_off = htons(IP_DF); - niph->protocol = IPPROTO_TCP; + niph->protocol = protocol; niph->check = 0; niph->saddr = oiph->daddr; niph->daddr = oiph->saddr; + niph->ttl = ttl; + + nskb->protocol = htons(ETH_P_IP); + + return niph; +} +EXPORT_SYMBOL_GPL(nf_reject_iphdr_put); + +void nf_reject_ip_tcphdr_put(struct sk_buff *nskb, const struct sk_buff *oldskb, + const struct tcphdr *oth) +{ + struct iphdr *niph = ip_hdr(nskb); + struct tcphdr *tcph; skb_reset_transport_header(nskb); tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); @@ -69,9 +78,9 @@ void nf_send_reset(struct sk_buff *oldskb, int hook) tcph->dest = oth->source; tcph->doff = sizeof(struct tcphdr) / 4; - if (oth->ack) + if (oth->ack) { tcph->seq = oth->ack_seq; - else { + } else { tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + oldskb->len - ip_hdrlen(oldskb) - (oth->doff << 2)); @@ -84,16 +93,43 @@ void nf_send_reset(struct sk_buff *oldskb, int hook) nskb->ip_summed = CHECKSUM_PARTIAL; nskb->csum_start = (unsigned char *)tcph - nskb->head; nskb->csum_offset = offsetof(struct tcphdr, check); +} +EXPORT_SYMBOL_GPL(nf_reject_ip_tcphdr_put); + +/* Send RST reply */ +void nf_send_reset(struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + const struct iphdr *oiph; + struct iphdr *niph; + const struct tcphdr *oth; + struct tcphdr _oth; + + oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); + if (!oth) + return; + + if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) + return; + + oiph = ip_hdr(oldskb); + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + + LL_MAX_HEADER, GFP_ATOMIC); + if (!nskb) + return; /* ip_route_me_harder expects skb->dst to be set */ skb_dst_set_noref(nskb, skb_dst(oldskb)); - nskb->protocol = htons(ETH_P_IP); + skb_reserve(nskb, LL_MAX_HEADER); + niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, + ip4_dst_hoplimit(skb_dst(nskb))); + nf_reject_ip_tcphdr_put(nskb, oldskb, oth); + if (ip_route_me_harder(nskb, RTN_UNSPEC)) goto free_nskb; - niph->ttl = ip4_dst_hoplimit(skb_dst(nskb)); - /* "Never happens" */ if (nskb->len > dst_mtu(skb_dst(nskb))) goto free_nskb; -- cgit v1.2.3 From 8bfcdf6671b1c8006c52c3eaf9fd1b5dfcf41c3d Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sun, 26 Oct 2014 12:35:54 +0100 Subject: netfilter: nf_reject_ipv6: split nf_send_reset6() in smaller functions That can be reused by the reject bridge expression to build the reject packet. The new functions are: * nf_reject_ip6_tcphdr_get(): to sanitize and to obtain the TCP header. * nf_reject_ip6hdr_put(): to build the IPv6 header. * nf_reject_ip6_tcphdr_put(): to build the TCP header. Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/ipv6/nf_reject.h | 10 ++ net/ipv6/netfilter/nf_reject_ipv6.c | 175 ++++++++++++++++++++------------- 2 files changed, 119 insertions(+), 66 deletions(-) diff --git a/include/net/netfilter/ipv6/nf_reject.h b/include/net/netfilter/ipv6/nf_reject.h index 48e18810a9be..23216d48abf9 100644 --- a/include/net/netfilter/ipv6/nf_reject.h +++ b/include/net/netfilter/ipv6/nf_reject.h @@ -15,4 +15,14 @@ nf_send_unreach6(struct net *net, struct sk_buff *skb_in, unsigned char code, void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook); +const struct tcphdr *nf_reject_ip6_tcphdr_get(struct sk_buff *oldskb, + struct tcphdr *otcph, + unsigned int *otcplen, int hook); +struct ipv6hdr *nf_reject_ip6hdr_put(struct sk_buff *nskb, + const struct sk_buff *oldskb, + __be16 protocol, int hoplimit); +void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb, + const struct sk_buff *oldskb, + const struct tcphdr *oth, unsigned int otcplen); + #endif /* _IPV6_NF_REJECT_H */ diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c index 20d9defc6c59..015eb8a80766 100644 --- a/net/ipv6/netfilter/nf_reject_ipv6.c +++ b/net/ipv6/netfilter/nf_reject_ipv6.c @@ -12,116 +12,102 @@ #include #include #include +#include -void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook) +const struct tcphdr *nf_reject_ip6_tcphdr_get(struct sk_buff *oldskb, + struct tcphdr *otcph, + unsigned int *otcplen, int hook) { - struct sk_buff *nskb; - struct tcphdr otcph, *tcph; - unsigned int otcplen, hh_len; - int tcphoff, needs_ack; const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); - struct ipv6hdr *ip6h; -#define DEFAULT_TOS_VALUE 0x0U - const __u8 tclass = DEFAULT_TOS_VALUE; - struct dst_entry *dst = NULL; u8 proto; __be16 frag_off; - struct flowi6 fl6; - - if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || - (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { - pr_debug("addr is not unicast.\n"); - return; - } + int tcphoff; proto = oip6h->nexthdr; - tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto, &frag_off); + tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), + &proto, &frag_off); if ((tcphoff < 0) || (tcphoff > oldskb->len)) { pr_debug("Cannot get TCP header.\n"); - return; + return NULL; } - otcplen = oldskb->len - tcphoff; + *otcplen = oldskb->len - tcphoff; /* IP header checks: fragment, too short. */ - if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) { - pr_debug("proto(%d) != IPPROTO_TCP, " - "or too short. otcplen = %d\n", - proto, otcplen); - return; + if (proto != IPPROTO_TCP || *otcplen < sizeof(struct tcphdr)) { + pr_debug("proto(%d) != IPPROTO_TCP or too short (len = %d)\n", + proto, *otcplen); + return NULL; } - if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr))) - BUG(); + otcph = skb_header_pointer(oldskb, tcphoff, sizeof(struct tcphdr), + otcph); + if (otcph == NULL) + return NULL; /* No RST for RST. */ - if (otcph.rst) { + if (otcph->rst) { pr_debug("RST is set\n"); - return; + return NULL; } /* Check checksum. */ if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) { pr_debug("TCP checksum is invalid\n"); - return; - } - - memset(&fl6, 0, sizeof(fl6)); - fl6.flowi6_proto = IPPROTO_TCP; - fl6.saddr = oip6h->daddr; - fl6.daddr = oip6h->saddr; - fl6.fl6_sport = otcph.dest; - fl6.fl6_dport = otcph.source; - security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6)); - dst = ip6_route_output(net, NULL, &fl6); - if (dst == NULL || dst->error) { - dst_release(dst); - return; - } - dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); - if (IS_ERR(dst)) - return; - - hh_len = (dst->dev->hard_header_len + 15)&~15; - nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) - + sizeof(struct tcphdr) + dst->trailer_len, - GFP_ATOMIC); - - if (!nskb) { - net_dbg_ratelimited("cannot alloc skb\n"); - dst_release(dst); - return; + return NULL; } - skb_dst_set(nskb, dst); + return otcph; +} +EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_get); - skb_reserve(nskb, hh_len + dst->header_len); +struct ipv6hdr *nf_reject_ip6hdr_put(struct sk_buff *nskb, + const struct sk_buff *oldskb, + __be16 protocol, int hoplimit) +{ + struct ipv6hdr *ip6h; + const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); +#define DEFAULT_TOS_VALUE 0x0U + const __u8 tclass = DEFAULT_TOS_VALUE; skb_put(nskb, sizeof(struct ipv6hdr)); skb_reset_network_header(nskb); ip6h = ipv6_hdr(nskb); ip6_flow_hdr(ip6h, tclass, 0); - ip6h->hop_limit = ip6_dst_hoplimit(dst); - ip6h->nexthdr = IPPROTO_TCP; + ip6h->hop_limit = hoplimit; + ip6h->nexthdr = protocol; ip6h->saddr = oip6h->daddr; ip6h->daddr = oip6h->saddr; + nskb->protocol = htons(ETH_P_IPV6); + + return ip6h; +} +EXPORT_SYMBOL_GPL(nf_reject_ip6hdr_put); + +void nf_reject_ip6_tcphdr_put(struct sk_buff *nskb, + const struct sk_buff *oldskb, + const struct tcphdr *oth, unsigned int otcplen) +{ + struct tcphdr *tcph; + int needs_ack; + skb_reset_transport_header(nskb); tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); /* Truncate to length (no data) */ tcph->doff = sizeof(struct tcphdr)/4; - tcph->source = otcph.dest; - tcph->dest = otcph.source; + tcph->source = oth->dest; + tcph->dest = oth->source; - if (otcph.ack) { + if (oth->ack) { needs_ack = 0; - tcph->seq = otcph.ack_seq; + tcph->seq = oth->ack_seq; tcph->ack_seq = 0; } else { needs_ack = 1; - tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin - + otcplen - (otcph.doff<<2)); + tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + + otcplen - (oth->doff<<2)); tcph->seq = 0; } @@ -139,6 +125,63 @@ void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook) sizeof(struct tcphdr), IPPROTO_TCP, csum_partial(tcph, sizeof(struct tcphdr), 0)); +} +EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put); + +void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + struct tcphdr _otcph; + const struct tcphdr *otcph; + unsigned int otcplen, hh_len; + const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); + struct ipv6hdr *ip6h; + struct dst_entry *dst = NULL; + struct flowi6 fl6; + + if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || + (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { + pr_debug("addr is not unicast.\n"); + return; + } + + otcph = nf_reject_ip6_tcphdr_get(oldskb, &_otcph, &otcplen, hook); + if (!otcph) + return; + + memset(&fl6, 0, sizeof(fl6)); + fl6.flowi6_proto = IPPROTO_TCP; + fl6.saddr = oip6h->daddr; + fl6.daddr = oip6h->saddr; + fl6.fl6_sport = otcph->dest; + fl6.fl6_dport = otcph->source; + security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6)); + dst = ip6_route_output(net, NULL, &fl6); + if (dst == NULL || dst->error) { + dst_release(dst); + return; + } + dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); + if (IS_ERR(dst)) + return; + + hh_len = (dst->dev->hard_header_len + 15)&~15; + nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) + + sizeof(struct tcphdr) + dst->trailer_len, + GFP_ATOMIC); + + if (!nskb) { + net_dbg_ratelimited("cannot alloc skb\n"); + dst_release(dst); + return; + } + + skb_dst_set(nskb, dst); + + skb_reserve(nskb, hh_len + dst->header_len); + ip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, + ip6_dst_hoplimit(dst)); + nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen); nf_ct_attach(nskb, oldskb); -- cgit v1.2.3 From 523b929d5446c023e1219aa81455a8c766cac883 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sat, 25 Oct 2014 18:40:26 +0200 Subject: netfilter: nft_reject_bridge: don't use IP stack to reject traffic If the packet is received via the bridge stack, this cannot reject packets from the IP stack. This adds functions to build the reject packet and send it from the bridge stack. Comments and assumptions on this patch: 1) Validate the IPv4 and IPv6 headers before further processing, given that the packet comes from the bridge stack, we cannot assume they are clean. Truncated packets are dropped, we follow similar approach in the existing iptables match/target extensions that need to inspect layer 4 headers that is not available. This also includes packets that are directed to multicast and broadcast ethernet addresses. 2) br_deliver() is exported to inject the reject packet via bridge localout -> postrouting. So the approach is similar to what we already do in the iptables reject target. The reject packet is sent to the bridge port from which we have received the original packet. 3) The reject packet is forged based on the original packet. The TTL is set based on sysctl_ip_default_ttl for IPv4 and per-net ipv6.devconf_all hoplimit for IPv6. Signed-off-by: Pablo Neira Ayuso --- net/bridge/br_forward.c | 1 + net/bridge/netfilter/nft_reject_bridge.c | 263 +++++++++++++++++++++++++++++-- 2 files changed, 254 insertions(+), 10 deletions(-) diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c index 992ec49a96aa..44cb786b925a 100644 --- a/net/bridge/br_forward.c +++ b/net/bridge/br_forward.c @@ -112,6 +112,7 @@ void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb) kfree_skb(skb); } +EXPORT_SYMBOL_GPL(br_deliver); /* called with rcu_read_lock */ void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0) diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c index a76479535df2..31b27e1bab9f 100644 --- a/net/bridge/netfilter/nft_reject_bridge.c +++ b/net/bridge/netfilter/nft_reject_bridge.c @@ -16,6 +16,237 @@ #include #include #include +#include +#include +#include "../br_private.h" + +static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb, + struct sk_buff *nskb) +{ + struct ethhdr *eth; + + eth = (struct ethhdr *)skb_push(nskb, ETH_HLEN); + skb_reset_mac_header(nskb); + ether_addr_copy(eth->h_source, eth_hdr(oldskb)->h_dest); + ether_addr_copy(eth->h_dest, eth_hdr(oldskb)->h_source); + eth->h_proto = eth_hdr(oldskb)->h_proto; + skb_pull(nskb, ETH_HLEN); +} + +static int nft_reject_iphdr_validate(struct sk_buff *oldskb) +{ + struct iphdr *iph; + u32 len; + + if (!pskb_may_pull(oldskb, sizeof(struct iphdr))) + return 0; + + iph = ip_hdr(oldskb); + if (iph->ihl < 5 || iph->version != 4) + return 0; + + len = ntohs(iph->tot_len); + if (oldskb->len < len) + return 0; + else if (len < (iph->ihl*4)) + return 0; + + if (!pskb_may_pull(oldskb, iph->ihl*4)) + return 0; + + return 1; +} + +static void nft_reject_br_send_v4_tcp_reset(struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + struct iphdr *niph; + const struct tcphdr *oth; + struct tcphdr _oth; + + if (!nft_reject_iphdr_validate(oldskb)) + return; + + oth = nf_reject_ip_tcphdr_get(oldskb, &_oth, hook); + if (!oth) + return; + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + + LL_MAX_HEADER, GFP_ATOMIC); + if (!nskb) + return; + + skb_reserve(nskb, LL_MAX_HEADER); + niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP, + sysctl_ip_default_ttl); + nf_reject_ip_tcphdr_put(nskb, oldskb, oth); + niph->ttl = sysctl_ip_default_ttl; + niph->tot_len = htons(nskb->len); + ip_send_check(niph); + + nft_reject_br_push_etherhdr(oldskb, nskb); + + br_deliver(br_port_get_rcu(oldskb->dev), nskb); +} + +static void nft_reject_br_send_v4_unreach(struct sk_buff *oldskb, int hook, + u8 code) +{ + struct sk_buff *nskb; + struct iphdr *niph; + struct icmphdr *icmph; + unsigned int len; + void *payload; + __wsum csum; + + if (!nft_reject_iphdr_validate(oldskb)) + return; + + /* IP header checks: fragment. */ + if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) + return; + + /* RFC says return as much as we can without exceeding 576 bytes. */ + len = min_t(unsigned int, 536, oldskb->len); + + if (!pskb_may_pull(oldskb, len)) + return; + + if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), 0)) + return; + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmphdr) + + LL_MAX_HEADER + len, GFP_ATOMIC); + if (!nskb) + return; + + skb_reserve(nskb, LL_MAX_HEADER); + niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP, + sysctl_ip_default_ttl); + + skb_reset_transport_header(nskb); + icmph = (struct icmphdr *)skb_put(nskb, sizeof(struct icmphdr)); + memset(icmph, 0, sizeof(*icmph)); + icmph->type = ICMP_DEST_UNREACH; + icmph->code = code; + + payload = skb_put(nskb, len); + memcpy(payload, skb_network_header(oldskb), len); + + csum = csum_partial((void *)icmph, len + sizeof(struct icmphdr), 0); + icmph->checksum = csum_fold(csum); + + niph->tot_len = htons(nskb->len); + ip_send_check(niph); + + nft_reject_br_push_etherhdr(oldskb, nskb); + + br_deliver(br_port_get_rcu(oldskb->dev), nskb); +} + +static int nft_reject_ip6hdr_validate(struct sk_buff *oldskb) +{ + struct ipv6hdr *hdr; + u32 pkt_len; + + if (!pskb_may_pull(oldskb, sizeof(struct ipv6hdr))) + return 0; + + hdr = ipv6_hdr(oldskb); + if (hdr->version != 6) + return 0; + + pkt_len = ntohs(hdr->payload_len); + if (pkt_len + sizeof(struct ipv6hdr) > oldskb->len) + return 0; + + return 1; +} + +static void nft_reject_br_send_v6_tcp_reset(struct net *net, + struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + const struct tcphdr *oth; + struct tcphdr _oth; + unsigned int otcplen; + struct ipv6hdr *nip6h; + + if (!nft_reject_ip6hdr_validate(oldskb)) + return; + + oth = nf_reject_ip6_tcphdr_get(oldskb, &_oth, &otcplen, hook); + if (!oth) + return; + + nskb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(struct tcphdr) + + LL_MAX_HEADER, GFP_ATOMIC); + if (!nskb) + return; + + skb_reserve(nskb, LL_MAX_HEADER); + nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, + net->ipv6.devconf_all->hop_limit); + nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen); + nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr)); + + nft_reject_br_push_etherhdr(oldskb, nskb); + + br_deliver(br_port_get_rcu(oldskb->dev), nskb); +} + +static void nft_reject_br_send_v6_unreach(struct net *net, + struct sk_buff *oldskb, int hook, + u8 code) +{ + struct sk_buff *nskb; + struct ipv6hdr *nip6h; + struct icmp6hdr *icmp6h; + unsigned int len; + void *payload; + + if (!nft_reject_ip6hdr_validate(oldskb)) + return; + + /* Include "As much of invoking packet as possible without the ICMPv6 + * packet exceeding the minimum IPv6 MTU" in the ICMP payload. + */ + len = min_t(unsigned int, 1220, oldskb->len); + + if (!pskb_may_pull(oldskb, len)) + return; + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct icmp6hdr) + + LL_MAX_HEADER + len, GFP_ATOMIC); + if (!nskb) + return; + + skb_reserve(nskb, LL_MAX_HEADER); + nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6, + net->ipv6.devconf_all->hop_limit); + + skb_reset_transport_header(nskb); + icmp6h = (struct icmp6hdr *)skb_put(nskb, sizeof(struct icmp6hdr)); + memset(icmp6h, 0, sizeof(*icmp6h)); + icmp6h->icmp6_type = ICMPV6_DEST_UNREACH; + icmp6h->icmp6_code = code; + + payload = skb_put(nskb, len); + memcpy(payload, skb_network_header(oldskb), len); + nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr)); + + icmp6h->icmp6_cksum = + csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr, + nskb->len - sizeof(struct ipv6hdr), + IPPROTO_ICMPV6, + csum_partial(icmp6h, + nskb->len - sizeof(struct ipv6hdr), + 0)); + + nft_reject_br_push_etherhdr(oldskb, nskb); + + br_deliver(br_port_get_rcu(oldskb->dev), nskb); +} static void nft_reject_bridge_eval(const struct nft_expr *expr, struct nft_data data[NFT_REG_MAX + 1], @@ -23,35 +254,46 @@ static void nft_reject_bridge_eval(const struct nft_expr *expr, { struct nft_reject *priv = nft_expr_priv(expr); struct net *net = dev_net((pkt->in != NULL) ? pkt->in : pkt->out); + const unsigned char *dest = eth_hdr(pkt->skb)->h_dest; + + if (is_broadcast_ether_addr(dest) || + is_multicast_ether_addr(dest)) + goto out; switch (eth_hdr(pkt->skb)->h_proto) { case htons(ETH_P_IP): switch (priv->type) { case NFT_REJECT_ICMP_UNREACH: - nf_send_unreach(pkt->skb, priv->icmp_code); + nft_reject_br_send_v4_unreach(pkt->skb, + pkt->ops->hooknum, + priv->icmp_code); break; case NFT_REJECT_TCP_RST: - nf_send_reset(pkt->skb, pkt->ops->hooknum); + nft_reject_br_send_v4_tcp_reset(pkt->skb, + pkt->ops->hooknum); break; case NFT_REJECT_ICMPX_UNREACH: - nf_send_unreach(pkt->skb, - nft_reject_icmp_code(priv->icmp_code)); + nft_reject_br_send_v4_unreach(pkt->skb, + pkt->ops->hooknum, + nft_reject_icmp_code(priv->icmp_code)); break; } break; case htons(ETH_P_IPV6): switch (priv->type) { case NFT_REJECT_ICMP_UNREACH: - nf_send_unreach6(net, pkt->skb, priv->icmp_code, - pkt->ops->hooknum); + nft_reject_br_send_v6_unreach(net, pkt->skb, + pkt->ops->hooknum, + priv->icmp_code); break; case NFT_REJECT_TCP_RST: - nf_send_reset6(net, pkt->skb, pkt->ops->hooknum); + nft_reject_br_send_v6_tcp_reset(net, pkt->skb, + pkt->ops->hooknum); break; case NFT_REJECT_ICMPX_UNREACH: - nf_send_unreach6(net, pkt->skb, - nft_reject_icmpv6_code(priv->icmp_code), - pkt->ops->hooknum); + nft_reject_br_send_v6_unreach(net, pkt->skb, + pkt->ops->hooknum, + nft_reject_icmpv6_code(priv->icmp_code)); break; } break; @@ -59,6 +301,7 @@ static void nft_reject_bridge_eval(const struct nft_expr *expr, /* No explicit way to reject this protocol, drop it. */ break; } +out: data[NFT_REG_VERDICT].verdict = NF_DROP; } -- cgit v1.2.3 From 127917c29a432c3b798e014a1714e9c1af0f87fe Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 27 Oct 2014 14:08:17 +0100 Subject: netfilter: nft_reject_bridge: restrict reject to prerouting and input Restrict the reject expression to the prerouting and input bridge hooks. If we allow this to be used from forward or any other later bridge hook, if the frame is flooded to several ports, we'll end up sending several reject packets, one per cloned packet. Signed-off-by: Pablo Neira Ayuso --- net/bridge/netfilter/nft_reject_bridge.c | 33 +++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c index 31b27e1bab9f..654c9018e3e7 100644 --- a/net/bridge/netfilter/nft_reject_bridge.c +++ b/net/bridge/netfilter/nft_reject_bridge.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "../br_private.h" static void nft_reject_br_push_etherhdr(struct sk_buff *oldskb, @@ -305,12 +306,34 @@ out: data[NFT_REG_VERDICT].verdict = NF_DROP; } +static int nft_reject_bridge_validate_hooks(const struct nft_chain *chain) +{ + struct nft_base_chain *basechain; + + if (chain->flags & NFT_BASE_CHAIN) { + basechain = nft_base_chain(chain); + + switch (basechain->ops[0].hooknum) { + case NF_BR_PRE_ROUTING: + case NF_BR_LOCAL_IN: + break; + default: + return -EOPNOTSUPP; + } + } + return 0; +} + static int nft_reject_bridge_init(const struct nft_ctx *ctx, const struct nft_expr *expr, const struct nlattr * const tb[]) { struct nft_reject *priv = nft_expr_priv(expr); - int icmp_code; + int icmp_code, err; + + err = nft_reject_bridge_validate_hooks(ctx->chain); + if (err < 0) + return err; if (tb[NFTA_REJECT_TYPE] == NULL) return -EINVAL; @@ -359,6 +382,13 @@ nla_put_failure: return -1; } +static int nft_reject_bridge_validate(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nft_data **data) +{ + return nft_reject_bridge_validate_hooks(ctx->chain); +} + static struct nft_expr_type nft_reject_bridge_type; static const struct nft_expr_ops nft_reject_bridge_ops = { .type = &nft_reject_bridge_type, @@ -366,6 +396,7 @@ static const struct nft_expr_ops nft_reject_bridge_ops = { .eval = nft_reject_bridge_eval, .init = nft_reject_bridge_init, .dump = nft_reject_bridge_dump, + .validate = nft_reject_bridge_validate, }; static struct nft_expr_type nft_reject_bridge_type __read_mostly = { -- cgit v1.2.3