Re: [PATCH 1/1] netfilter: xt_recent: Add optional mask option forxt_recent

From: Pablo Neira Ayuso
Date: Tue May 01 2012 - 21:01:22 EST

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On Tue, Mar 06, 2012 at 01:24:44PM +0200, Denys Fedoryshchenko wrote:
> Use case for this feature:
> 1)In some occasions if you need to allow,block,match specific subnet.
> 2)I can use recent as a trigger when netfilter rule matches, with mask 0.0.0.0
>
> Example:
>
> If you ping 8.8.8.8, after that you can't ping 2.2.2.10
>
> Tested for backward compatibility:
> )old (userspace) iptables, new kernel
> )old kernel, new iptables
> )new kernel, new iptables
>
> Signed-off-by: Denys Fedoryshchenko <denys@xxxxxxxxxxx>
> ---
> include/linux/netfilter.h | 11 +++++
> include/linux/netfilter/xt_recent.h | 10 +++++
> net/netfilter/xt_recent.c | 70 +++++++++++++++++++++++++++++++----
> 3 files changed, 83 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
> index b809265..c132de6 100644
> --- a/include/linux/netfilter.h
> +++ b/include/linux/netfilter.h
> @@ -85,6 +85,17 @@ static inline int NF_DROP_GETERR(int verdict)
> return -(verdict >> NF_VERDICT_QBITS);
> }
>
> +
> +static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
> + union nf_inet_addr *result,
> + const union nf_inet_addr *mask)
> +{
> + result->all[0] = a1->all[0] & mask->all[0];
> + result->all[1] = a1->all[1] & mask->all[1];
> + result->all[2] = a1->all[2] & mask->all[2];
> + result->all[3] = a1->all[3] & mask->all[3];
> +}

Please, put this function in the xt_recent. I prefer leave it there
until more clients of it show up.

> +
> static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
> const union nf_inet_addr *a2)
> {
> diff --git a/include/linux/netfilter/xt_recent.h b/include/linux/netfilter/xt_recent.h
> index 83318e0..6ef36c1 100644
> --- a/include/linux/netfilter/xt_recent.h
> +++ b/include/linux/netfilter/xt_recent.h
> @@ -32,4 +32,14 @@ struct xt_recent_mtinfo {
> __u8 side;
> };
>
> +struct xt_recent_mtinfo_v1 {
> + __u32 seconds;
> + __u32 hit_count;
> + __u8 check_set;
> + __u8 invert;
> + char name[XT_RECENT_NAME_LEN];
> + __u8 side;
> + union nf_inet_addr mask;
> +};
> +
> #endif /* _LINUX_NETFILTER_XT_RECENT_H */
> diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
> index d2ff15a..bdc38fa 100644
> --- a/net/netfilter/xt_recent.c
> +++ b/net/netfilter/xt_recent.c
> @@ -75,6 +75,7 @@ struct recent_entry {
> struct recent_table {
> struct list_head list;
> char name[XT_RECENT_NAME_LEN];
> + union nf_inet_addr mask;
> unsigned int refcnt;
> unsigned int entries;
> struct list_head lru_list;
> @@ -228,10 +229,11 @@ recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
> {
> struct net *net = dev_net(par->in ? par->in : par->out);
> struct recent_net *recent_net = recent_pernet(net);
> - const struct xt_recent_mtinfo *info = par->matchinfo;
> + const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
> struct recent_table *t;
> struct recent_entry *e;
> union nf_inet_addr addr = {};
> + union nf_inet_addr addr_masked;
> u_int8_t ttl;
> bool ret = info->invert;
>
> @@ -261,12 +263,15 @@ recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
>
> spin_lock_bh(&recent_lock);
> t = recent_table_lookup(recent_net, info->name);
> - e = recent_entry_lookup(t, &addr, par->family,
> +
> + nf_inet_addr_mask(&addr, &addr_masked, &t->mask);
> +
> + e = recent_entry_lookup(t, &addr_masked, par->family,
> (info->check_set & XT_RECENT_TTL) ? ttl : 0);
> if (e == NULL) {
> if (!(info->check_set & XT_RECENT_SET))
> goto out;
> - e = recent_entry_init(t, &addr, par->family, ttl);
> + e = recent_entry_init(t, &addr_masked, par->family, ttl);
> if (e == NULL)
> par->hotdrop = true;
> ret = !ret;
> @@ -306,10 +311,10 @@ out:
> return ret;
> }
>
> -static int recent_mt_check(const struct xt_mtchk_param *par)
> +static int recent_mt_check(const struct xt_mtchk_param *par,
> + const struct xt_recent_mtinfo_v1 *info)
> {
> struct recent_net *recent_net = recent_pernet(par->net);
> - const struct xt_recent_mtinfo *info = par->matchinfo;
> struct recent_table *t;
> #ifdef CONFIG_PROC_FS
> struct proc_dir_entry *pde;
> @@ -361,6 +366,8 @@ static int recent_mt_check(const struct xt_mtchk_param *par)
> goto out;
> }
> t->refcnt = 1;
> +
> + memcpy(&t->mask, &info->mask, sizeof(t->mask));
> strcpy(t->name, info->name);
> INIT_LIST_HEAD(&t->lru_list);
> for (i = 0; i < ip_list_hash_size; i++)
> @@ -385,10 +392,37 @@ out:
> return ret;
> }
>
> +static int recent_mt_check_v0(const struct xt_mtchk_param *par)
> +{
> + const struct xt_recent_mtinfo_v0 *info_v0 = par->matchinfo;
> + struct xt_recent_mtinfo_v1 *info_v1 = par->matchinfo;
> + int ret;
> +
> + info_v1 = kzalloc(sizeof(struct xt_recent_mtinfo_v1),
> + GFP_KERNEL);

Better allocate this in the stack. It's fairly small and it is used
temporarily.

> + if (info_v1 == NULL)
> + return -ENOMEM;
> +
> +
> + /* Copy old data */
> + memcpy(info_v1, info_v0, sizeof(struct xt_recent_mtinfo));
> + /* Default mask will make same behavior as old recent */
> + memset(info_v1->mask.all, 0xFF, sizeof(info_v1->mask.all));
> + ret = recent_mt_check(par, info_v1);
> +
> + kfree(info_v1);
> + return ret;
> +}
> +
> +static int recent_mt_check_v1(const struct xt_mtchk_param *par)
> +{
> + return recent_mt_check(par, par->matchinfo);
> +}
> +
> static void recent_mt_destroy(const struct xt_mtdtor_param *par)
> {
> struct recent_net *recent_net = recent_pernet(par->net);
> - const struct xt_recent_mtinfo *info = par->matchinfo;
> + const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
> struct recent_table *t;
>
> mutex_lock(&recent_mutex);
> @@ -625,7 +659,7 @@ static struct xt_match recent_mt_reg[] __read_mostly = {
> .family = NFPROTO_IPV4,
> .match = recent_mt,
> .matchsize = sizeof(struct xt_recent_mtinfo),
> - .checkentry = recent_mt_check,
> + .checkentry = recent_mt_check_v0,
> .destroy = recent_mt_destroy,
> .me = THIS_MODULE,
> },
> @@ -635,10 +669,30 @@ static struct xt_match recent_mt_reg[] __read_mostly = {
> .family = NFPROTO_IPV6,
> .match = recent_mt,
> .matchsize = sizeof(struct xt_recent_mtinfo),
> - .checkentry = recent_mt_check,
> + .checkentry = recent_mt_check_v0,
> .destroy = recent_mt_destroy,
> .me = THIS_MODULE,
> },
> + {
> + .name = "recent",
> + .revision = 1,
> + .family = NFPROTO_IPV4,
> + .match = recent_mt,
> + .matchsize = sizeof(struct xt_recent_mtinfo_v1),
> + .checkentry = recent_mt_check_v1,
> + .destroy = recent_mt_destroy,
> + .me = THIS_MODULE,
> + },
> + {
> + .name = "recent",
> + .revision = 1,
> + .family = NFPROTO_IPV6,
> + .match = recent_mt,
> + .matchsize = sizeof(struct xt_recent_mtinfo_v1),
> + .checkentry = recent_mt_check_v1,
> + .destroy = recent_mt_destroy,
> + .me = THIS_MODULE,
> + }
> };
>
> static int __init recent_mt_init(void)
> --
> 1.7.3.4
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