TPROXY: implemented IP_RECVORIGDSTADDR socket option
In case UDP traffic is redirected to a local UDP socket, the originally addressed destination address/port cannot be recovered with the in-kernel tproxy. This patch adds an IP_RECVORIGDSTADDR sockopt that enables a IP_ORIGDSTADDR ancillary message in recvmsg(). This ancillary message contains the original destination address/port of the packet being received. Signed-off-by: Balazs Scheidler <bazsi@balabit.hu> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -80,6 +80,10 @@ struct in_addr {
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/* BSD compatibility */
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#define IP_RECVRETOPTS IP_RETOPTS
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/* TProxy original addresses */
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#define IP_ORIGDSTADDR 20
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#define IP_RECVORIGDSTADDR IP_ORIGDSTADDR
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/* IP_MTU_DISCOVER values */
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#define IP_PMTUDISC_DONT 0 /* Never send DF frames */
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#define IP_PMTUDISC_WANT 1 /* Use per route hints */
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@ -48,6 +48,7 @@
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#define IP_CMSG_RECVOPTS 8
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#define IP_CMSG_RETOPTS 16
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#define IP_CMSG_PASSSEC 32
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#define IP_CMSG_ORIGDSTADDR 64
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/*
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* SOL_IP control messages.
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@ -126,6 +127,27 @@ static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
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security_release_secctx(secdata, seclen);
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}
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void ip_cmsg_recv_dstaddr(struct msghdr *msg, struct sk_buff *skb)
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{
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struct sockaddr_in sin;
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struct iphdr *iph = ip_hdr(skb);
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u16 *ports = (u16 *) skb_transport_header(skb);
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if (skb_transport_offset(skb) + 4 > skb->len)
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return;
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/* All current transport protocols have the port numbers in the
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* first four bytes of the transport header and this function is
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* written with this assumption in mind.
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*/
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sin.sin_family = AF_INET;
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sin.sin_addr.s_addr = iph->daddr;
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sin.sin_port = ports[1];
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memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
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put_cmsg(msg, SOL_IP, IP_ORIGDSTADDR, sizeof(sin), &sin);
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}
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void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
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{
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@ -160,6 +182,12 @@ void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
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if (flags & 1)
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ip_cmsg_recv_security(msg, skb);
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if ((flags>>=1) == 0)
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return;
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if (flags & 1)
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ip_cmsg_recv_dstaddr(msg, skb);
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}
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int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc)
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@ -421,7 +449,8 @@ static int do_ip_setsockopt(struct sock *sk, int level,
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(1<<IP_ROUTER_ALERT) | (1<<IP_FREEBIND) |
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(1<<IP_PASSSEC) | (1<<IP_TRANSPARENT))) ||
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optname == IP_MULTICAST_TTL ||
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optname == IP_MULTICAST_LOOP) {
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optname == IP_MULTICAST_LOOP ||
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optname == IP_RECVORIGDSTADDR) {
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if (optlen >= sizeof(int)) {
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if (get_user(val, (int __user *) optval))
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return -EFAULT;
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@ -509,6 +538,12 @@ static int do_ip_setsockopt(struct sock *sk, int level,
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else
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inet->cmsg_flags &= ~IP_CMSG_PASSSEC;
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break;
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case IP_RECVORIGDSTADDR:
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if (val)
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inet->cmsg_flags |= IP_CMSG_ORIGDSTADDR;
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else
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inet->cmsg_flags &= ~IP_CMSG_ORIGDSTADDR;
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break;
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case IP_TOS: /* This sets both TOS and Precedence */
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if (sk->sk_type == SOCK_STREAM) {
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val &= ~3;
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@ -1022,6 +1057,9 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
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case IP_PASSSEC:
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val = (inet->cmsg_flags & IP_CMSG_PASSSEC) != 0;
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break;
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case IP_RECVORIGDSTADDR:
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val = (inet->cmsg_flags & IP_CMSG_ORIGDSTADDR) != 0;
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break;
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case IP_TOS:
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val = inet->tos;
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break;
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