From 01555e74bde51444c6898ef1800fb2bc697d479e Mon Sep 17 00:00:00 2001 From: Harout Hedeshian Date: Mon, 15 Jun 2015 18:40:43 -0600 Subject: [PATCH] netfilter: xt_socket: add XT_SOCKET_RESTORESKMARK flag xt_socket is useful for matching sockets with IP_TRANSPARENT and taking some action on the matching packets. However, it lacks the ability to match only a small subset of transparent sockets. Suppose there are 2 applications, each with its own set of transparent sockets. The first application wants all matching packets dropped, while the second application wants them forwarded somewhere else. Add the ability to retore the skb->mark from the sk_mark. The mark is only restored if a matching socket is found and the transparent / nowildcard conditions are satisfied. Now the 2 hypothetical applications can differentiate their sockets based on a mark value set with SO_MARK. iptables -t mangle -I PREROUTING -m socket --transparent \ --restore-skmark -j action iptables -t mangle -A action -m mark --mark 10 -j action2 iptables -t mangle -A action -m mark --mark 11 -j action3 Signed-off-by: Harout Hedeshian Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/xt_socket.h | 8 ++++ net/netfilter/xt_socket.c | 59 +++++++++++++++++++++--- 2 files changed, 61 insertions(+), 6 deletions(-) diff --git a/include/uapi/linux/netfilter/xt_socket.h b/include/uapi/linux/netfilter/xt_socket.h index 6315e2ac3474..87644f832494 100644 --- a/include/uapi/linux/netfilter/xt_socket.h +++ b/include/uapi/linux/netfilter/xt_socket.h @@ -6,6 +6,7 @@ enum { XT_SOCKET_TRANSPARENT = 1 << 0, XT_SOCKET_NOWILDCARD = 1 << 1, + XT_SOCKET_RESTORESKMARK = 1 << 2, }; struct xt_socket_mtinfo1 { @@ -18,4 +19,11 @@ struct xt_socket_mtinfo2 { }; #define XT_SOCKET_FLAGS_V2 (XT_SOCKET_TRANSPARENT | XT_SOCKET_NOWILDCARD) +struct xt_socket_mtinfo3 { + __u8 flags; +}; +#define XT_SOCKET_FLAGS_V3 (XT_SOCKET_TRANSPARENT \ + | XT_SOCKET_NOWILDCARD \ + | XT_SOCKET_RESTORESKMARK) + #endif /* _XT_SOCKET_H */ diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c index e092cb046326..43e26c881100 100644 --- a/net/netfilter/xt_socket.c +++ b/net/netfilter/xt_socket.c @@ -205,6 +205,7 @@ static bool socket_match(const struct sk_buff *skb, struct xt_action_param *par, const struct xt_socket_mtinfo1 *info) { + struct sk_buff *pskb = (struct sk_buff *)skb; struct sock *sk = skb->sk; if (!sk) @@ -226,6 +227,10 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, if (info->flags & XT_SOCKET_TRANSPARENT) transparent = xt_socket_sk_is_transparent(sk); + if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard && + transparent) + pskb->mark = sk->sk_mark; + if (sk != skb->sk) sock_gen_put(sk); @@ -247,7 +252,7 @@ socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) } static bool -socket_mt4_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) +socket_mt4_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par) { return socket_match(skb, par, par->matchinfo); } @@ -371,9 +376,10 @@ static struct sock *xt_socket_lookup_slow_v6(const struct sk_buff *skb, } static bool -socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) +socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; + struct sk_buff *pskb = (struct sk_buff *)skb; struct sock *sk = skb->sk; if (!sk) @@ -395,6 +401,10 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) if (info->flags & XT_SOCKET_TRANSPARENT) transparent = xt_socket_sk_is_transparent(sk); + if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard && + transparent) + pskb->mark = sk->sk_mark; + if (sk != skb->sk) sock_gen_put(sk); @@ -428,6 +438,19 @@ static int socket_mt_v2_check(const struct xt_mtchk_param *par) return 0; } +static int socket_mt_v3_check(const struct xt_mtchk_param *par) +{ + const struct xt_socket_mtinfo3 *info = + (struct xt_socket_mtinfo3 *)par->matchinfo; + + if (info->flags & ~XT_SOCKET_FLAGS_V3) { + pr_info("unknown flags 0x%x\n", + info->flags & ~XT_SOCKET_FLAGS_V3); + return -EINVAL; + } + return 0; +} + static struct xt_match socket_mt_reg[] __read_mostly = { { .name = "socket", @@ -442,7 +465,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = { .name = "socket", .revision = 1, .family = NFPROTO_IPV4, - .match = socket_mt4_v1_v2, + .match = socket_mt4_v1_v2_v3, .checkentry = socket_mt_v1_check, .matchsize = sizeof(struct xt_socket_mtinfo1), .hooks = (1 << NF_INET_PRE_ROUTING) | @@ -454,7 +477,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = { .name = "socket", .revision = 1, .family = NFPROTO_IPV6, - .match = socket_mt6_v1_v2, + .match = socket_mt6_v1_v2_v3, .checkentry = socket_mt_v1_check, .matchsize = sizeof(struct xt_socket_mtinfo1), .hooks = (1 << NF_INET_PRE_ROUTING) | @@ -466,7 +489,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = { .name = "socket", .revision = 2, .family = NFPROTO_IPV4, - .match = socket_mt4_v1_v2, + .match = socket_mt4_v1_v2_v3, .checkentry = socket_mt_v2_check, .matchsize = sizeof(struct xt_socket_mtinfo1), .hooks = (1 << NF_INET_PRE_ROUTING) | @@ -478,13 +501,37 @@ static struct xt_match socket_mt_reg[] __read_mostly = { .name = "socket", .revision = 2, .family = NFPROTO_IPV6, - .match = socket_mt6_v1_v2, + .match = socket_mt6_v1_v2_v3, .checkentry = socket_mt_v2_check, .matchsize = sizeof(struct xt_socket_mtinfo1), .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_IN), .me = THIS_MODULE, }, +#endif + { + .name = "socket", + .revision = 3, + .family = NFPROTO_IPV4, + .match = socket_mt4_v1_v2_v3, + .checkentry = socket_mt_v3_check, + .matchsize = sizeof(struct xt_socket_mtinfo1), + .hooks = (1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN), + .me = THIS_MODULE, + }, +#ifdef XT_SOCKET_HAVE_IPV6 + { + .name = "socket", + .revision = 3, + .family = NFPROTO_IPV6, + .match = socket_mt6_v1_v2_v3, + .checkentry = socket_mt_v3_check, + .matchsize = sizeof(struct xt_socket_mtinfo1), + .hooks = (1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN), + .me = THIS_MODULE, + }, #endif }; -- 2.20.1