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netfilter: nfnetlink_osf: extract nfnetlink_subsystem code from xt_osf.c
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Move nfnetlink osf subsystem from xt_osf.c to standalone module so we can
reuse it from the new nft_ost extension.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Fernando Fernandez Mancera authored and Pablo Neira Ayuso committed Jul 30, 2018
1 parent f6b7b5f commit f932495
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Showing 4 changed files with 169 additions and 154 deletions.
11 changes: 11 additions & 0 deletions include/uapi/linux/netfilter/nf_osf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,8 @@ struct nf_osf_nlmsg {
struct tcphdr tcp;
};

extern struct list_head nf_osf_fingers[2];

/* Defines for IANA option kinds */
enum iana_options {
OSFOPT_EOL = 0, /* End of options */
Expand All @@ -94,4 +96,13 @@ enum nf_osf_attr_type {
OSF_ATTR_MAX,
};

/*
* Add/remove fingerprint from the kernel.
*/
enum nf_osf_msg_types {
OSF_MSG_ADD,
OSF_MSG_REMOVE,
OSF_MSG_MAX,
};

#endif /* _NF_OSF_H */
9 changes: 1 addition & 8 deletions include/uapi/linux/netfilter/xt_osf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,13 +47,6 @@
#define xt_osf_nlmsg nf_osf_nlmsg

#define xt_osf_attr_type nf_osf_attr_type
/*
* Add/remove fingerprint from the kernel.
*/
enum xt_osf_msg_types {
OSF_MSG_ADD,
OSF_MSG_REMOVE,
OSF_MSG_MAX,
};
#define xt_osf_msg_types nf_osf_msg_types

#endif /* _XT_OSF_H */
154 changes: 154 additions & 0 deletions net/netfilter/nfnetlink_osf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,13 @@
#include <net/netfilter/nf_log.h>
#include <linux/netfilter/nf_osf.h>

/*
* Indexed by dont-fragment bit.
* It is the only constant value in the fingerprint.
*/
struct list_head nf_osf_fingers[2];
EXPORT_SYMBOL_GPL(nf_osf_fingers);

static inline int nf_osf_ttl(const struct sk_buff *skb,
int ttl_check, unsigned char f_ttl)
{
Expand Down Expand Up @@ -279,4 +286,151 @@ const char *nf_osf_find(const struct sk_buff *skb,
}
EXPORT_SYMBOL_GPL(nf_osf_find);

static const struct nla_policy nfnl_osf_policy[OSF_ATTR_MAX + 1] = {
[OSF_ATTR_FINGER] = { .len = sizeof(struct nf_osf_user_finger) },
};

static int nfnl_osf_add_callback(struct net *net, struct sock *ctnl,
struct sk_buff *skb, const struct nlmsghdr *nlh,
const struct nlattr * const osf_attrs[],
struct netlink_ext_ack *extack)
{
struct nf_osf_user_finger *f;
struct nf_osf_finger *kf = NULL, *sf;
int err = 0;

if (!capable(CAP_NET_ADMIN))
return -EPERM;

if (!osf_attrs[OSF_ATTR_FINGER])
return -EINVAL;

if (!(nlh->nlmsg_flags & NLM_F_CREATE))
return -EINVAL;

f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

kf = kmalloc(sizeof(struct nf_osf_finger), GFP_KERNEL);
if (!kf)
return -ENOMEM;

memcpy(&kf->finger, f, sizeof(struct nf_osf_user_finger));

list_for_each_entry(sf, &nf_osf_fingers[!!f->df], finger_entry) {
if (memcmp(&sf->finger, f, sizeof(struct nf_osf_user_finger)))
continue;

kfree(kf);
kf = NULL;

if (nlh->nlmsg_flags & NLM_F_EXCL)
err = -EEXIST;
break;
}

/*
* We are protected by nfnl mutex.
*/
if (kf)
list_add_tail_rcu(&kf->finger_entry, &nf_osf_fingers[!!f->df]);

return err;
}

static int nfnl_osf_remove_callback(struct net *net, struct sock *ctnl,
struct sk_buff *skb,
const struct nlmsghdr *nlh,
const struct nlattr * const osf_attrs[],
struct netlink_ext_ack *extack)
{
struct nf_osf_user_finger *f;
struct nf_osf_finger *sf;
int err = -ENOENT;

if (!capable(CAP_NET_ADMIN))
return -EPERM;

if (!osf_attrs[OSF_ATTR_FINGER])
return -EINVAL;

f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

list_for_each_entry(sf, &nf_osf_fingers[!!f->df], finger_entry) {
if (memcmp(&sf->finger, f, sizeof(struct nf_osf_user_finger)))
continue;

/*
* We are protected by nfnl mutex.
*/
list_del_rcu(&sf->finger_entry);
kfree_rcu(sf, rcu_head);

err = 0;
break;
}

return err;
}

static const struct nfnl_callback nfnl_osf_callbacks[OSF_MSG_MAX] = {
[OSF_MSG_ADD] = {
.call = nfnl_osf_add_callback,
.attr_count = OSF_ATTR_MAX,
.policy = nfnl_osf_policy,
},
[OSF_MSG_REMOVE] = {
.call = nfnl_osf_remove_callback,
.attr_count = OSF_ATTR_MAX,
.policy = nfnl_osf_policy,
},
};

static const struct nfnetlink_subsystem nfnl_osf_subsys = {
.name = "osf",
.subsys_id = NFNL_SUBSYS_OSF,
.cb_count = OSF_MSG_MAX,
.cb = nfnl_osf_callbacks,
};

static int __init nfnl_osf_init(void)
{
int err = -EINVAL;
int i;

for (i = 0; i < ARRAY_SIZE(nf_osf_fingers); ++i)
INIT_LIST_HEAD(&nf_osf_fingers[i]);

err = nfnetlink_subsys_register(&nfnl_osf_subsys);
if (err < 0) {
pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
goto err_out_exit;
}
return 0;

err_out_exit:
return err;
}

static void __exit nfnl_osf_fini(void)
{
struct nf_osf_finger *f;
int i;

nfnetlink_subsys_unregister(&nfnl_osf_subsys);

rcu_read_lock();
for (i = 0; i < ARRAY_SIZE(nf_osf_fingers); ++i) {
list_for_each_entry_rcu(f, &nf_osf_fingers[i], finger_entry) {
list_del_rcu(&f->finger_entry);
kfree_rcu(f, rcu_head);
}
}
rcu_read_unlock();

rcu_barrier();
}

module_init(nfnl_osf_init);
module_exit(nfnl_osf_fini);

MODULE_LICENSE("GPL");
149 changes: 3 additions & 146 deletions net/netfilter/xt_osf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,118 +37,6 @@
#include <net/netfilter/nf_log.h>
#include <linux/netfilter/xt_osf.h>

/*
* Indexed by dont-fragment bit.
* It is the only constant value in the fingerprint.
*/
static struct list_head xt_osf_fingers[2];

static const struct nla_policy xt_osf_policy[OSF_ATTR_MAX + 1] = {
[OSF_ATTR_FINGER] = { .len = sizeof(struct xt_osf_user_finger) },
};

static int xt_osf_add_callback(struct net *net, struct sock *ctnl,
struct sk_buff *skb, const struct nlmsghdr *nlh,
const struct nlattr * const osf_attrs[],
struct netlink_ext_ack *extack)
{
struct xt_osf_user_finger *f;
struct xt_osf_finger *kf = NULL, *sf;
int err = 0;

if (!capable(CAP_NET_ADMIN))
return -EPERM;

if (!osf_attrs[OSF_ATTR_FINGER])
return -EINVAL;

if (!(nlh->nlmsg_flags & NLM_F_CREATE))
return -EINVAL;

f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

kf = kmalloc(sizeof(struct xt_osf_finger), GFP_KERNEL);
if (!kf)
return -ENOMEM;

memcpy(&kf->finger, f, sizeof(struct xt_osf_user_finger));

list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
continue;

kfree(kf);
kf = NULL;

if (nlh->nlmsg_flags & NLM_F_EXCL)
err = -EEXIST;
break;
}

/*
* We are protected by nfnl mutex.
*/
if (kf)
list_add_tail_rcu(&kf->finger_entry, &xt_osf_fingers[!!f->df]);

return err;
}

static int xt_osf_remove_callback(struct net *net, struct sock *ctnl,
struct sk_buff *skb,
const struct nlmsghdr *nlh,
const struct nlattr * const osf_attrs[],
struct netlink_ext_ack *extack)
{
struct xt_osf_user_finger *f;
struct xt_osf_finger *sf;
int err = -ENOENT;

if (!capable(CAP_NET_ADMIN))
return -EPERM;

if (!osf_attrs[OSF_ATTR_FINGER])
return -EINVAL;

f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
continue;

/*
* We are protected by nfnl mutex.
*/
list_del_rcu(&sf->finger_entry);
kfree_rcu(sf, rcu_head);

err = 0;
break;
}

return err;
}

static const struct nfnl_callback xt_osf_nfnetlink_callbacks[OSF_MSG_MAX] = {
[OSF_MSG_ADD] = {
.call = xt_osf_add_callback,
.attr_count = OSF_ATTR_MAX,
.policy = xt_osf_policy,
},
[OSF_MSG_REMOVE] = {
.call = xt_osf_remove_callback,
.attr_count = OSF_ATTR_MAX,
.policy = xt_osf_policy,
},
};

static const struct nfnetlink_subsystem xt_osf_nfnetlink = {
.name = "osf",
.subsys_id = NFNL_SUBSYS_OSF,
.cb_count = OSF_MSG_MAX,
.cb = xt_osf_nfnetlink_callbacks,
};

static bool
xt_osf_match_packet(const struct sk_buff *skb, struct xt_action_param *p)
{
Expand All @@ -159,7 +47,7 @@ xt_osf_match_packet(const struct sk_buff *skb, struct xt_action_param *p)
return false;

return nf_osf_match(skb, xt_family(p), xt_hooknum(p), xt_in(p),
xt_out(p), info, net, xt_osf_fingers);
xt_out(p), info, net, nf_osf_fingers);
}

static struct xt_match xt_osf_match = {
Expand All @@ -177,52 +65,21 @@ static struct xt_match xt_osf_match = {

static int __init xt_osf_init(void)
{
int err = -EINVAL;
int i;

for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i)
INIT_LIST_HEAD(&xt_osf_fingers[i]);

err = nfnetlink_subsys_register(&xt_osf_nfnetlink);
if (err < 0) {
pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
goto err_out_exit;
}
int err;

err = xt_register_match(&xt_osf_match);
if (err) {
pr_err("Failed to register OS fingerprint "
"matching module (%d)\n", err);
goto err_out_remove;
return err;
}

return 0;

err_out_remove:
nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
err_out_exit:
return err;
}

static void __exit xt_osf_fini(void)
{
struct xt_osf_finger *f;
int i;

nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
xt_unregister_match(&xt_osf_match);

rcu_read_lock();
for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i) {

list_for_each_entry_rcu(f, &xt_osf_fingers[i], finger_entry) {
list_del_rcu(&f->finger_entry);
kfree_rcu(f, rcu_head);
}
}
rcu_read_unlock();

rcu_barrier();
}

module_init(xt_osf_init);
Expand Down

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