netfilter: xt_conntrack: Support bit-shifting for CONNMARK & MARK targets.

This patch introduces a new feature that allows bitshifting (left
and right) operations to co-operate with existing iptables options.

Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jack Ma <jack.ma@alliedtelesis.co.nz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/uapi/linux/netfilter/xt_connmark.h b/include/uapi/linux/netfilter/xt_connmark.h
index 408a965..1aa5c95 100644 (file)
--- a/include/uapi/linux/netfilter/xt_connmark.h
+++ b/include/uapi/linux/netfilter/xt_connmark.h
@@ -19,11 +19,21 @@ enum {
        XT_CONNMARK_RESTORE
 };
 
+enum {
+       D_SHIFT_LEFT = 0,
+       D_SHIFT_RIGHT,
+};
+
 struct xt_connmark_tginfo1 {
        __u32 ctmark, ctmask, nfmask;
        __u8 mode;
 };
 
+struct xt_connmark_tginfo2 {
+       __u32 ctmark, ctmask, nfmask;
+       __u8 shift_dir, shift_bits, mode;
+};
+
 struct xt_connmark_mtinfo1 {
        __u32 mark, mask;
        __u8 invert;

diff --git a/net/netfilter/xt_connmark.c b/net/netfilter/xt_connmark.c
index 809639c..773da82 100644 (file)
--- a/net/netfilter/xt_connmark.c
+++ b/net/netfilter/xt_connmark.c
@@ -36,9 +36,10 @@ MODULE_ALIAS("ipt_connmark");
 MODULE_ALIAS("ip6t_connmark");
 
 static unsigned int
-connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
+connmark_tg_shift(struct sk_buff *skb,
+               const struct xt_connmark_tginfo1 *info,
+               u8 shift_bits, u8 shift_dir)
 {
-       const struct xt_connmark_tginfo1 *info = par->targinfo;
        enum ip_conntrack_info ctinfo;
        struct nf_conn *ct;
        u_int32_t newmark;
@@ -50,6 +51,10 @@ connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
        switch (info->mode) {
        case XT_CONNMARK_SET:
                newmark = (ct->mark & ~info->ctmask) ^ info->ctmark;
+               if (shift_dir == D_SHIFT_RIGHT)
+                       newmark >>= shift_bits;
+               else
+                       newmark <<= shift_bits;
                if (ct->mark != newmark) {
                        ct->mark = newmark;
                        nf_conntrack_event_cache(IPCT_MARK, ct);
@@ -57,7 +62,11 @@ connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
                break;
        case XT_CONNMARK_SAVE:
                newmark = (ct->mark & ~info->ctmask) ^
-                         (skb->mark & info->nfmask);
+                         (skb->mark & info->nfmask);
+               if (shift_dir == D_SHIFT_RIGHT)
+                       newmark >>= shift_bits;
+               else
+                       newmark <<= shift_bits;
                if (ct->mark != newmark) {
                        ct->mark = newmark;
                        nf_conntrack_event_cache(IPCT_MARK, ct);
@@ -65,14 +74,34 @@ connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
                break;
        case XT_CONNMARK_RESTORE:
                newmark = (skb->mark & ~info->nfmask) ^
-                         (ct->mark & info->ctmask);
+                         (ct->mark & info->ctmask);
+               if (shift_dir == D_SHIFT_RIGHT)
+                       newmark >>= shift_bits;
+               else
+                       newmark <<= shift_bits;
                skb->mark = newmark;
                break;
        }
-
        return XT_CONTINUE;
 }
 
+static unsigned int
+connmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
+{
+       const struct xt_connmark_tginfo1 *info = par->targinfo;
+
+       return connmark_tg_shift(skb, info, 0, 0);
+}
+
+static unsigned int
+connmark_tg_v2(struct sk_buff *skb, const struct xt_action_param *par)
+{
+       const struct xt_connmark_tginfo2 *info = par->targinfo;
+
+       return connmark_tg_shift(skb, (const struct xt_connmark_tginfo1 *)info,
+                                info->shift_bits, info->shift_dir);
+}
+
 static int connmark_tg_check(const struct xt_tgchk_param *par)
 {
        int ret;
@@ -119,15 +148,27 @@ static void connmark_mt_destroy(const struct xt_mtdtor_param *par)
        nf_ct_netns_put(par->net, par->family);
 }
 
-static struct xt_target connmark_tg_reg __read_mostly = {
-       .name           = "CONNMARK",
-       .revision       = 1,
-       .family         = NFPROTO_UNSPEC,
-       .checkentry     = connmark_tg_check,
-       .target         = connmark_tg,
-       .targetsize     = sizeof(struct xt_connmark_tginfo1),
-       .destroy        = connmark_tg_destroy,
-       .me             = THIS_MODULE,
+static struct xt_target connmark_tg_reg[] __read_mostly = {
+       {
+               .name           = "CONNMARK",
+               .revision       = 1,
+               .family         = NFPROTO_UNSPEC,
+               .checkentry     = connmark_tg_check,
+               .target         = connmark_tg,
+               .targetsize     = sizeof(struct xt_connmark_tginfo1),
+               .destroy        = connmark_tg_destroy,
+               .me             = THIS_MODULE,
+       },
+       {
+               .name           = "CONNMARK",
+               .revision       = 2,
+               .family         = NFPROTO_UNSPEC,
+               .checkentry     = connmark_tg_check,
+               .target         = connmark_tg_v2,
+               .targetsize     = sizeof(struct xt_connmark_tginfo2),
+               .destroy        = connmark_tg_destroy,
+               .me             = THIS_MODULE,
+       }
 };
 
 static struct xt_match connmark_mt_reg __read_mostly = {
@@ -145,12 +186,14 @@ static int __init connmark_mt_init(void)
 {
        int ret;
 
-       ret = xt_register_target(&connmark_tg_reg);
+       ret = xt_register_targets(connmark_tg_reg,
+                                 ARRAY_SIZE(connmark_tg_reg));
        if (ret < 0)
                return ret;
        ret = xt_register_match(&connmark_mt_reg);
        if (ret < 0) {
-               xt_unregister_target(&connmark_tg_reg);
+               xt_unregister_targets(connmark_tg_reg,
+                                     ARRAY_SIZE(connmark_tg_reg));
                return ret;
        }
        return 0;
@@ -159,7 +202,7 @@ static int __init connmark_mt_init(void)
 static void __exit connmark_mt_exit(void)
 {
        xt_unregister_match(&connmark_mt_reg);
-       xt_unregister_target(&connmark_tg_reg);
+       xt_unregister_target(connmark_tg_reg);
 }
 
 module_init(connmark_mt_init);