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; }