diff options
Diffstat (limited to 'net/netfilter/nf_synproxy_core.c')
| -rw-r--r-- | net/netfilter/nf_synproxy_core.c | 898 |
1 files changed, 860 insertions, 38 deletions
diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c index 8ce74ed985c0..b101f187eda8 100644 --- a/net/netfilter/nf_synproxy_core.c +++ b/net/netfilter/nf_synproxy_core.c @@ -10,16 +10,16 @@ #include <net/netns/generic.h> #include <linux/proc_fs.h> -#include <linux/netfilter_ipv4/ip_tables.h> -#include <linux/netfilter/x_tables.h> -#include <linux/netfilter/xt_tcpudp.h> -#include <linux/netfilter/xt_SYNPROXY.h> +#include <linux/netfilter_ipv6.h> +#include <linux/netfilter/nf_synproxy.h> #include <net/netfilter/nf_conntrack.h> +#include <net/netfilter/nf_conntrack_ecache.h> #include <net/netfilter/nf_conntrack_extend.h> #include <net/netfilter/nf_conntrack_seqadj.h> #include <net/netfilter/nf_conntrack_synproxy.h> #include <net/netfilter/nf_conntrack_zones.h> +#include <net/netfilter/nf_synproxy.h> unsigned int synproxy_net_id; EXPORT_SYMBOL_GPL(synproxy_net_id); @@ -57,7 +57,7 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff, case TCPOPT_MSS: if (opsize == TCPOLEN_MSS) { opts->mss = get_unaligned_be16(ptr); - opts->options |= XT_SYNPROXY_OPT_MSS; + opts->options |= NF_SYNPROXY_OPT_MSS; } break; case TCPOPT_WINDOW: @@ -65,19 +65,19 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff, opts->wscale = *ptr; if (opts->wscale > TCP_MAX_WSCALE) opts->wscale = TCP_MAX_WSCALE; - opts->options |= XT_SYNPROXY_OPT_WSCALE; + opts->options |= NF_SYNPROXY_OPT_WSCALE; } break; case TCPOPT_TIMESTAMP: if (opsize == TCPOLEN_TIMESTAMP) { opts->tsval = get_unaligned_be32(ptr); opts->tsecr = get_unaligned_be32(ptr + 4); - opts->options |= XT_SYNPROXY_OPT_TIMESTAMP; + opts->options |= NF_SYNPROXY_OPT_TIMESTAMP; } break; case TCPOPT_SACK_PERM: if (opsize == TCPOLEN_SACK_PERM) - opts->options |= XT_SYNPROXY_OPT_SACK_PERM; + opts->options |= NF_SYNPROXY_OPT_SACK_PERM; break; } @@ -89,36 +89,36 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff, } EXPORT_SYMBOL_GPL(synproxy_parse_options); -unsigned int synproxy_options_size(const struct synproxy_options *opts) +static unsigned int +synproxy_options_size(const struct synproxy_options *opts) { unsigned int size = 0; - if (opts->options & XT_SYNPROXY_OPT_MSS) + if (opts->options & NF_SYNPROXY_OPT_MSS) size += TCPOLEN_MSS_ALIGNED; - if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP) + if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) size += TCPOLEN_TSTAMP_ALIGNED; - else if (opts->options & XT_SYNPROXY_OPT_SACK_PERM) + else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM) size += TCPOLEN_SACKPERM_ALIGNED; - if (opts->options & XT_SYNPROXY_OPT_WSCALE) + if (opts->options & NF_SYNPROXY_OPT_WSCALE) size += TCPOLEN_WSCALE_ALIGNED; return size; } -EXPORT_SYMBOL_GPL(synproxy_options_size); -void +static void synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts) { __be32 *ptr = (__be32 *)(th + 1); u8 options = opts->options; - if (options & XT_SYNPROXY_OPT_MSS) + if (options & NF_SYNPROXY_OPT_MSS) *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | opts->mss); - if (options & XT_SYNPROXY_OPT_TIMESTAMP) { - if (options & XT_SYNPROXY_OPT_SACK_PERM) + if (options & NF_SYNPROXY_OPT_TIMESTAMP) { + if (options & NF_SYNPROXY_OPT_SACK_PERM) *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | (TCPOLEN_SACK_PERM << 16) | (TCPOPT_TIMESTAMP << 8) | @@ -131,58 +131,56 @@ synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts) *ptr++ = htonl(opts->tsval); *ptr++ = htonl(opts->tsecr); - } else if (options & XT_SYNPROXY_OPT_SACK_PERM) + } else if (options & NF_SYNPROXY_OPT_SACK_PERM) *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | (TCPOPT_SACK_PERM << 8) | TCPOLEN_SACK_PERM); - if (options & XT_SYNPROXY_OPT_WSCALE) + if (options & NF_SYNPROXY_OPT_WSCALE) *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_WINDOW << 16) | (TCPOLEN_WINDOW << 8) | opts->wscale); } -EXPORT_SYMBOL_GPL(synproxy_build_options); -void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info, +void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info, struct synproxy_options *opts) { opts->tsecr = opts->tsval; opts->tsval = tcp_time_stamp_raw() & ~0x3f; - if (opts->options & XT_SYNPROXY_OPT_WSCALE) { + if (opts->options & NF_SYNPROXY_OPT_WSCALE) { opts->tsval |= opts->wscale; opts->wscale = info->wscale; } else opts->tsval |= 0xf; - if (opts->options & XT_SYNPROXY_OPT_SACK_PERM) + if (opts->options & NF_SYNPROXY_OPT_SACK_PERM) opts->tsval |= 1 << 4; - if (opts->options & XT_SYNPROXY_OPT_ECN) + if (opts->options & NF_SYNPROXY_OPT_ECN) opts->tsval |= 1 << 5; } EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie); -void synproxy_check_timestamp_cookie(struct synproxy_options *opts) +static void +synproxy_check_timestamp_cookie(struct synproxy_options *opts) { opts->wscale = opts->tsecr & 0xf; if (opts->wscale != 0xf) - opts->options |= XT_SYNPROXY_OPT_WSCALE; + opts->options |= NF_SYNPROXY_OPT_WSCALE; - opts->options |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0; + opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0; - opts->options |= opts->tsecr & (1 << 5) ? XT_SYNPROXY_OPT_ECN : 0; + opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0; } -EXPORT_SYMBOL_GPL(synproxy_check_timestamp_cookie); -unsigned int synproxy_tstamp_adjust(struct sk_buff *skb, - unsigned int protoff, - struct tcphdr *th, - struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - const struct nf_conn_synproxy *synproxy) +static unsigned int +synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, + struct tcphdr *th, struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + const struct nf_conn_synproxy *synproxy) { unsigned int optoff, optend; __be32 *ptr, old; @@ -193,7 +191,7 @@ unsigned int synproxy_tstamp_adjust(struct sk_buff *skb, optoff = protoff + sizeof(struct tcphdr); optend = protoff + th->doff * 4; - if (!skb_make_writable(skb, optend)) + if (skb_ensure_writable(skb, optend)) return 0; while (optoff < optend) { @@ -232,7 +230,6 @@ unsigned int synproxy_tstamp_adjust(struct sk_buff *skb, } return 1; } -EXPORT_SYMBOL_GPL(synproxy_tstamp_adjust); static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = { .len = sizeof(struct nf_conn_synproxy), @@ -413,5 +410,830 @@ static void __exit synproxy_core_exit(void) module_init(synproxy_core_init); module_exit(synproxy_core_exit); +static struct iphdr * +synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr, + __be32 daddr) +{ + struct iphdr *iph; + + skb_reset_network_header(skb); + iph = skb_put(skb, sizeof(*iph)); + iph->version = 4; + iph->ihl = sizeof(*iph) / 4; + iph->tos = 0; + iph->id = 0; + iph->frag_off = htons(IP_DF); + iph->ttl = net->ipv4.sysctl_ip_default_ttl; + iph->protocol = IPPROTO_TCP; + iph->check = 0; + iph->saddr = saddr; + iph->daddr = daddr; + + return iph; +} + +static void +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) +{ + 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; + nskb->csum_offset = offsetof(struct tcphdr, check); + + skb_dst_set_noref(nskb, skb_dst(skb)); + nskb->protocol = htons(ETH_P_IP); + if (ip_route_me_harder(net, nskb, RTN_UNSPEC)) + goto free_nskb; + + if (nfct) { + nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo); + nf_conntrack_get(nfct); + } + + ip_local_out(net, nskb->sk, nskb); + return; + +free_nskb: + kfree_skb(nskb); +} + +void +synproxy_send_client_synack(struct net *net, + const struct sk_buff *skb, const struct tcphdr *th, + const struct synproxy_options *opts) +{ + struct sk_buff *nskb; + struct iphdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + u16 mss = opts->mss; + + iph = ip_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->dest; + nth->dest = th->source; + nth->seq = htonl(__cookie_v4_init_sequence(iph, th, &mss)); + nth->ack_seq = htonl(ntohl(th->seq) + 1); + tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK; + if (opts->options & NF_SYNPROXY_OPT_ECN) + tcp_flag_word(nth) |= TCP_FLAG_ECE; + nth->doff = tcp_hdr_size / 4; + nth->window = 0; + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp(net, skb, nskb, skb_nfct(skb), + IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); +} +EXPORT_SYMBOL_GPL(synproxy_send_client_synack); + +static void +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; + unsigned int tcp_hdr_size; + + iph = ip_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->source; + nth->dest = th->dest; + nth->seq = htonl(recv_seq - 1); + /* ack_seq is used to relay our ISN to the synproxy hook to initialize + * sequence number translation once a connection tracking entry exists. + */ + nth->ack_seq = htonl(ntohl(th->ack_seq) - 1); + tcp_flag_word(nth) = TCP_FLAG_SYN; + if (opts->options & NF_SYNPROXY_OPT_ECN) + tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR; + nth->doff = tcp_hdr_size / 4; + nth->window = th->window; + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW, + niph, nth, tcp_hdr_size); +} + +static void +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) +{ + struct sk_buff *nskb; + struct iphdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + + iph = ip_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->dest; + nth->dest = th->source; + nth->seq = htonl(ntohl(th->ack_seq)); + nth->ack_seq = htonl(ntohl(th->seq) + 1); + tcp_flag_word(nth) = TCP_FLAG_ACK; + nth->doff = tcp_hdr_size / 4; + nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin); + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); +} + +static void +synproxy_send_client_ack(struct net *net, + const struct sk_buff *skb, const struct tcphdr *th, + const struct synproxy_options *opts) +{ + struct sk_buff *nskb; + struct iphdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + + iph = ip_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->source; + nth->dest = th->dest; + nth->seq = htonl(ntohl(th->seq) + 1); + nth->ack_seq = th->ack_seq; + tcp_flag_word(nth) = TCP_FLAG_ACK; + nth->doff = tcp_hdr_size / 4; + nth->window = htons(ntohs(th->window) >> opts->wscale); + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp(net, skb, nskb, skb_nfct(skb), + IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); +} + +bool +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); + if (mss == 0) { + this_cpu_inc(snet->stats->cookie_invalid); + return false; + } + + this_cpu_inc(snet->stats->cookie_valid); + opts->mss = mss; + opts->options |= NF_SYNPROXY_OPT_MSS; + + if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) + synproxy_check_timestamp_cookie(opts); + + synproxy_send_server_syn(net, skb, th, opts, recv_seq); + return true; +} +EXPORT_SYMBOL_GPL(synproxy_recv_client_ack); + +unsigned int +ipv4_synproxy_hook(void *priv, struct sk_buff *skb, + const struct nf_hook_state *nhs) +{ + 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; + struct synproxy_options opts = {}; + const struct ip_ct_tcp *state; + struct tcphdr *th, _th; + unsigned int thoff; + + ct = nf_ct_get(skb, &ctinfo); + if (!ct) + return NF_ACCEPT; + + synproxy = nfct_synproxy(ct); + if (!synproxy) + return NF_ACCEPT; + + if (nf_is_loopback_packet(skb) || + ip_hdr(skb)->protocol != IPPROTO_TCP) + return NF_ACCEPT; + + thoff = ip_hdrlen(skb); + th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); + if (!th) + return NF_DROP; + + state = &ct->proto.tcp; + switch (state->state) { + case TCP_CONNTRACK_CLOSE: + if (th->rst && !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { + nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - + ntohl(th->seq) + 1); + break; + } + + if (!th->syn || th->ack || + CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) + break; + + /* Reopened connection - reset the sequence number and timestamp + * adjustments, they will get initialized once the connection is + * reestablished. + */ + nf_ct_seqadj_init(ct, ctinfo, 0); + synproxy->tsoff = 0; + this_cpu_inc(snet->stats->conn_reopened); + + /* fall through */ + case TCP_CONNTRACK_SYN_SENT: + if (!synproxy_parse_options(skb, thoff, th, &opts)) + return NF_DROP; + + if (!th->syn && th->ack && + CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) { + /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1, + * therefore we need to add 1 to make the SYN sequence + * number match the one of first SYN. + */ + if (synproxy_recv_client_ack(net, skb, th, &opts, + ntohl(th->seq) + 1)) { + this_cpu_inc(snet->stats->cookie_retrans); + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } + } + + synproxy->isn = ntohl(th->ack_seq); + if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) + synproxy->its = opts.tsecr; + + nf_conntrack_event_cache(IPCT_SYNPROXY, ct); + break; + case TCP_CONNTRACK_SYN_RECV: + if (!th->syn || !th->ack) + break; + + if (!synproxy_parse_options(skb, thoff, th, &opts)) + return NF_DROP; + + if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) { + synproxy->tsoff = opts.tsval - synproxy->its; + nf_conntrack_event_cache(IPCT_SYNPROXY, ct); + } + + opts.options &= ~(NF_SYNPROXY_OPT_MSS | + NF_SYNPROXY_OPT_WSCALE | + NF_SYNPROXY_OPT_SACK_PERM); + + swap(opts.tsval, opts.tsecr); + synproxy_send_server_ack(net, state, skb, th, &opts); + + nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); + nf_conntrack_event_cache(IPCT_SEQADJ, ct); + + swap(opts.tsval, opts.tsecr); + synproxy_send_client_ack(net, skb, th, &opts); + + consume_skb(skb); + return NF_STOLEN; + default: + break; + } + + synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); + return NF_ACCEPT; +} +EXPORT_SYMBOL_GPL(ipv4_synproxy_hook); + +static const struct nf_hook_ops ipv4_synproxy_ops[] = { + { + .hook = ipv4_synproxy_hook, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_LOCAL_IN, + .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, + }, + { + .hook = ipv4_synproxy_hook, + .pf = NFPROTO_IPV4, + .hooknum = NF_INET_POST_ROUTING, + .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, + }, +}; + +int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net) +{ + int err; + + if (snet->hook_ref4 == 0) { + err = nf_register_net_hooks(net, ipv4_synproxy_ops, + ARRAY_SIZE(ipv4_synproxy_ops)); + if (err) + return err; + } + + snet->hook_ref4++; + return 0; +} +EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init); + +void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net) +{ + snet->hook_ref4--; + if (snet->hook_ref4 == 0) + nf_unregister_net_hooks(net, ipv4_synproxy_ops, + ARRAY_SIZE(ipv4_synproxy_ops)); +} +EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini); + +#if IS_ENABLED(CONFIG_IPV6) +static struct ipv6hdr * +synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb, + const struct in6_addr *saddr, + const struct in6_addr *daddr) +{ + struct ipv6hdr *iph; + + skb_reset_network_header(skb); + iph = skb_put(skb, sizeof(*iph)); + ip6_flow_hdr(iph, 0, 0); + iph->hop_limit = net->ipv6.devconf_all->hop_limit; + iph->nexthdr = IPPROTO_TCP; + iph->saddr = *saddr; + iph->daddr = *daddr; + + return iph; +} + +static void +synproxy_send_tcp_ipv6(struct net *net, + const struct sk_buff *skb, struct sk_buff *nskb, + struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo, + struct ipv6hdr *niph, struct tcphdr *nth, + unsigned int tcp_hdr_size) +{ + struct dst_entry *dst; + struct flowi6 fl6; + int err; + + nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0); + nskb->ip_summed = CHECKSUM_PARTIAL; + nskb->csum_start = (unsigned char *)nth - nskb->head; + nskb->csum_offset = offsetof(struct tcphdr, check); + + memset(&fl6, 0, sizeof(fl6)); + fl6.flowi6_proto = IPPROTO_TCP; + fl6.saddr = niph->saddr; + fl6.daddr = niph->daddr; + fl6.fl6_sport = nth->source; + fl6.fl6_dport = nth->dest; + security_skb_classify_flow((struct sk_buff *)skb, + flowi6_to_flowi(&fl6)); + err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false); + if (err) { + goto free_nskb; + } + + dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); + if (IS_ERR(dst)) + goto free_nskb; + + skb_dst_set(nskb, dst); + + if (nfct) { + nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo); + nf_conntrack_get(nfct); + } + + ip6_local_out(net, nskb->sk, nskb); + return; + +free_nskb: + kfree_skb(nskb); +} + +void +synproxy_send_client_synack_ipv6(struct net *net, + const struct sk_buff *skb, + const struct tcphdr *th, + const struct synproxy_options *opts) +{ + struct sk_buff *nskb; + struct ipv6hdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + u16 mss = opts->mss; + + iph = ipv6_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->dest; + nth->dest = th->source; + nth->seq = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss)); + nth->ack_seq = htonl(ntohl(th->seq) + 1); + tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK; + if (opts->options & NF_SYNPROXY_OPT_ECN) + tcp_flag_word(nth) |= TCP_FLAG_ECE; + nth->doff = tcp_hdr_size / 4; + nth->window = 0; + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb), + IP_CT_ESTABLISHED_REPLY, niph, nth, + tcp_hdr_size); +} +EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6); + +static void +synproxy_send_server_syn_ipv6(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 ipv6hdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + + iph = ipv6_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->source; + nth->dest = th->dest; + nth->seq = htonl(recv_seq - 1); + /* ack_seq is used to relay our ISN to the synproxy hook to initialize + * sequence number translation once a connection tracking entry exists. + */ + nth->ack_seq = htonl(ntohl(th->ack_seq) - 1); + tcp_flag_word(nth) = TCP_FLAG_SYN; + if (opts->options & NF_SYNPROXY_OPT_ECN) + tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR; + nth->doff = tcp_hdr_size / 4; + nth->window = th->window; + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general, + IP_CT_NEW, niph, nth, tcp_hdr_size); +} + +static void +synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state, + const struct sk_buff *skb, + const struct tcphdr *th, + const struct synproxy_options *opts) +{ + struct sk_buff *nskb; + struct ipv6hdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + + iph = ipv6_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->dest; + nth->dest = th->source; + nth->seq = htonl(ntohl(th->ack_seq)); + nth->ack_seq = htonl(ntohl(th->seq) + 1); + tcp_flag_word(nth) = TCP_FLAG_ACK; + nth->doff = tcp_hdr_size / 4; + nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin); + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth, + tcp_hdr_size); +} + +static void +synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb, + const struct tcphdr *th, + const struct synproxy_options *opts) +{ + struct sk_buff *nskb; + struct ipv6hdr *iph, *niph; + struct tcphdr *nth; + unsigned int tcp_hdr_size; + + iph = ipv6_hdr(skb); + + tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); + nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, + GFP_ATOMIC); + if (!nskb) + return; + skb_reserve(nskb, MAX_TCP_HEADER); + + niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr); + + skb_reset_transport_header(nskb); + nth = skb_put(nskb, tcp_hdr_size); + nth->source = th->source; + nth->dest = th->dest; + nth->seq = htonl(ntohl(th->seq) + 1); + nth->ack_seq = th->ack_seq; + tcp_flag_word(nth) = TCP_FLAG_ACK; + nth->doff = tcp_hdr_size / 4; + nth->window = htons(ntohs(th->window) >> opts->wscale); + nth->check = 0; + nth->urg_ptr = 0; + + synproxy_build_options(nth, opts); + + synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb), + IP_CT_ESTABLISHED_REPLY, niph, nth, + tcp_hdr_size); +} + +bool +synproxy_recv_client_ack_ipv6(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 = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1); + if (mss == 0) { + this_cpu_inc(snet->stats->cookie_invalid); + return false; + } + + this_cpu_inc(snet->stats->cookie_valid); + opts->mss = mss; + opts->options |= NF_SYNPROXY_OPT_MSS; + + if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) + synproxy_check_timestamp_cookie(opts); + + synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq); + return true; +} +EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6); + +unsigned int +ipv6_synproxy_hook(void *priv, struct sk_buff *skb, + const struct nf_hook_state *nhs) +{ + 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; + struct synproxy_options opts = {}; + const struct ip_ct_tcp *state; + struct tcphdr *th, _th; + __be16 frag_off; + u8 nexthdr; + int thoff; + + ct = nf_ct_get(skb, &ctinfo); + if (!ct) + return NF_ACCEPT; + + synproxy = nfct_synproxy(ct); + if (!synproxy) + return NF_ACCEPT; + + if (nf_is_loopback_packet(skb)) + return NF_ACCEPT; + + nexthdr = ipv6_hdr(skb)->nexthdr; + thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, + &frag_off); + if (thoff < 0 || nexthdr != IPPROTO_TCP) + return NF_ACCEPT; + + th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); + if (!th) + return NF_DROP; + + state = &ct->proto.tcp; + switch (state->state) { + case TCP_CONNTRACK_CLOSE: + if (th->rst && !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { + nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - + ntohl(th->seq) + 1); + break; + } + + if (!th->syn || th->ack || + CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) + break; + + /* Reopened connection - reset the sequence number and timestamp + * adjustments, they will get initialized once the connection is + * reestablished. + */ + nf_ct_seqadj_init(ct, ctinfo, 0); + synproxy->tsoff = 0; + this_cpu_inc(snet->stats->conn_reopened); + + /* fall through */ + case TCP_CONNTRACK_SYN_SENT: + if (!synproxy_parse_options(skb, thoff, th, &opts)) + return NF_DROP; + + if (!th->syn && th->ack && + CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) { + /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1, + * therefore we need to add 1 to make the SYN sequence + * number match the one of first SYN. + */ + if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts, + ntohl(th->seq) + 1)) { + this_cpu_inc(snet->stats->cookie_retrans); + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } + } + + synproxy->isn = ntohl(th->ack_seq); + if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) + synproxy->its = opts.tsecr; + + nf_conntrack_event_cache(IPCT_SYNPROXY, ct); + break; + case TCP_CONNTRACK_SYN_RECV: + if (!th->syn || !th->ack) + break; + + if (!synproxy_parse_options(skb, thoff, th, &opts)) + return NF_DROP; + + if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) { + synproxy->tsoff = opts.tsval - synproxy->its; + nf_conntrack_event_cache(IPCT_SYNPROXY, ct); + } + + opts.options &= ~(NF_SYNPROXY_OPT_MSS | + NF_SYNPROXY_OPT_WSCALE | + NF_SYNPROXY_OPT_SACK_PERM); + + swap(opts.tsval, opts.tsecr); + synproxy_send_server_ack_ipv6(net, state, skb, th, &opts); + + nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); + nf_conntrack_event_cache(IPCT_SEQADJ, ct); + + swap(opts.tsval, opts.tsecr); + synproxy_send_client_ack_ipv6(net, skb, th, &opts); + + consume_skb(skb); + return NF_STOLEN; + default: + break; + } + + synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); + return NF_ACCEPT; +} +EXPORT_SYMBOL_GPL(ipv6_synproxy_hook); + +static const struct nf_hook_ops ipv6_synproxy_ops[] = { + { + .hook = ipv6_synproxy_hook, + .pf = NFPROTO_IPV6, + .hooknum = NF_INET_LOCAL_IN, + .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, + }, + { + .hook = ipv6_synproxy_hook, + .pf = NFPROTO_IPV6, + .hooknum = NF_INET_POST_ROUTING, + .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, + }, +}; + +int +nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net) +{ + int err; + + if (snet->hook_ref6 == 0) { + err = nf_register_net_hooks(net, ipv6_synproxy_ops, + ARRAY_SIZE(ipv6_synproxy_ops)); + if (err) + return err; + } + + snet->hook_ref6++; + return 0; +} +EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init); + +void +nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net) +{ + snet->hook_ref6--; + if (snet->hook_ref6 == 0) + nf_unregister_net_hooks(net, ipv6_synproxy_ops, + ARRAY_SIZE(ipv6_synproxy_ops)); +} +EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini); +#endif /* CONFIG_IPV6 */ + MODULE_LICENSE("GPL"); MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); |