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Subject[PATCH 1/1] netfilter: xt_recent: Add optional mask option for xt_recent
Date
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@visp.net.lb>
---
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];
+}
+
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);
+ 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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