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Date: Thu, 25 Aug 2011 15:19:29 +0200
From: Pavel Machek <pavel@....cz>
To: Tonda <as@...milov.cz>
Cc: davem@...emloft.net, kuznet@....inr.ac.ru, jmorris@...ei.org,
yoshfuji@...ux-ipv6.org, kaber@...sh.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: TCP port firewall controlled by UDP packets
No comments, variables named in czech.
Ok for me but...
But first thing would be description what it is good for...?
Pavel
On Fri 2011-08-12 01:42:52, Tonda wrote:
> If unsure, say N.
> +
> +config TCPFIREWALL
> + tristate "TCP Firewall controlled by UDP queries"
> + depends on m
> diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
> --- a/net/ipv4/Makefile
> +++ b/net/ipv4/Makefile
> @@ -51,3 +51,4 @@
>
> obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
> xfrm4_output.o
> +obj-$(CONFIG_TCPFIREWALL) += tcpfirewall/
> diff --git a/net/ipv4/tcpfirewall/Makefile b/net/ipv4/tcpfirewall/Makefile
> --- a/net/ipv4/tcpfirewall/Makefile
> +++ b/net/ipv4/tcpfirewall/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_TCPFIREWALL) += tcpfirewall.o
> diff --git a/net/ipv4/tcpfirewall/tcpfirewall.c b/net/ipv4/tcpfirewall/tcpfirewall.c
> --- a/net/ipv4/tcpfirewall/tcpfirewall.c
> +++ b/net/ipv4/tcpfirewall/tcpfirewall.c
> @@ -0,0 +1,451 @@
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/skbuff.h>
> +#include <linux/in.h>
> +#include <linux/if_packet.h>
> +#include <linux/tcp.h>
> +#include <linux/udp.h>
> +#include <net/tcp.h>
> +#include <net/udp.h>
> +
> +struct net_protocol {
> + int (*handler)(struct sk_buff *skb);
> + void (*err_handler)(struct sk_buff *skb, u32 info);
> + int (*gso_send_check)(struct sk_buff *skb);
> + struct sk_buff *(*gso_segment)(struct sk_buff *skb,
> + u32 features);
> + struct sk_buff **(*gro_receive)(struct sk_buff **head,
> + struct sk_buff *skb);
> + int (*gro_complete)(struct sk_buff *skb);
> + unsigned int no_policy:1,
> + netns_ok:1;
> +};
> +
> +MODULE_LICENSE("GPL");
> +
> +static unsigned long inet_protos = 0x01234567;
> +
> +struct net_protocol **_inet_protos;
> +
> +module_param(inet_protos, ulong, 0);
> +
> +static int *otviraky;
> +static int *zaviraky;
> +
> +static int pocetotviraku;
> +static int pocetzaviraku;
> +static int stav;
> +static int packetcounter;
> +static int tcpport;
> +static int open;
> +static int firewall;
> +
> +int (*tcpv4recv) (struct sk_buff *skb);
> +int (*udprecv) (struct sk_buff *skb);
> +
> +int udpcontroller(struct sk_buff *skb)
> +{
> + const struct udphdr *uh;
> +
> + if (skb->pkt_type != PACKET_HOST) {
> + kfree_skb(skb);
> + return 0;
> + }
> +
> + if (!pskb_may_pull(skb, sizeof(struct tcphdr))) {
> + kfree_skb(skb);
> + return 0;
> + }
> +
> + uh = udp_hdr(skb);
> +
> + if (pocetotviraku == 0)
> + return udprecv(skb);
> +
> + if (!open) {
> + if (uh->dest == otviraky[stav]) {
> + ++stav;
> + packetcounter = 0;
> +
> + if (stav == pocetotviraku) {
> + open = 1;
> + stav = 0;
> + }
> + } else {
> + if (packetcounter <= 16) {
> + ++packetcounter;
> + if (packetcounter > 16)
> + stav = 0;
> + }
> + }
> + } else {
> + if (uh->dest == zaviraky[stav]) {
> + ++stav;
> + packetcounter = 0;
> +
> + if (stav == pocetzaviraku) {
> + open = 0;
> + stav = 0;
> + }
> + } else {
> + if (packetcounter <= 16) {
> + ++packetcounter;
> + if (packetcounter > 16)
> + stav = 0;
> + }
> + }
> + }
> +
> +
> + return udprecv(skb);
> +}
> +
> +int tcpfirewall(struct sk_buff *skb)
> +{
> + const struct tcphdr *th;
> +
> + if (skb->pkt_type != PACKET_HOST) {
> + kfree_skb(skb);
> + return 0;
> + }
> +
> + if (!pskb_may_pull(skb, sizeof(struct tcphdr))) {
> + kfree_skb(skb);
> + return 0;
> + }
> +
> + th = tcp_hdr(skb);
> +
> + if (th->dest == tcpport) {
> + if (firewall == 1 && !open) {
> + /*tcpv4sendreset(NULL, skb);*/
> + kfree_skb(skb);
> + return 0;
> + }
> + }
> +
> + return tcpv4recv(skb);
> +}
> +
> +static struct net_protocol *zalohatcp;
> +static struct net_protocol *zalohaudp;
> +static struct net_protocol mytcp;
> +static struct net_protocol myudp;
> +
> +static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buffer)
> +{
> + if (!strcmp(attr->name, "firewall")) {
> + if (firewall)
> + buffer[0] = '1';
> + else
> + buffer[0] = '0';
> +
> + buffer[1] = '\n';
> + return 2;
> + }
> +
> + if (!strcmp(attr->name, "tcpport")) {
> + sprintf(buffer, "%d\n", ntohs(tcpport));
> + return strlen(buffer)+1;
> + }
> +
> + if (!strcmp(attr->name, "openers")) {
> + int i;
> + char *znak;
> + if (pocetotviraku == 0)
> + return 0;
> + buffer[0] = '\0';
> + znak = kmalloc(10, GFP_KERNEL);
> + for (i = 0; i < pocetotviraku; ++i) {
> + sprintf(znak, "%d ", ntohs(otviraky[i]));
> + strcat(buffer, znak);
> + }
> + kfree(znak);
> + buffer[strlen(buffer)-1] = '\n';
> + return strlen(buffer);
> + }
> +
> + if (!strcmp(attr->name, "closers")) {
> + int i;
> + char *znak;
> + if (pocetzaviraku == 0)
> + return 0;
> + buffer[0] = '\0';
> + znak = kmalloc(10, GFP_KERNEL);
> + for (i = 0; i < pocetzaviraku; ++i) {
> + sprintf(znak, "%d ", ntohs(zaviraky[i]));
> + strcat(buffer, znak);
> + }
> + kfree(znak);
> + buffer[strlen(buffer)-1] = '\n';
> + return strlen(buffer);
> + }
> +
> + if (!strcmp(attr->name, "open")) {
> + if (open)
> + buffer[0] = '1';
> + else
> + buffer[0] = '0';
> +
> + buffer[1] = '\n';
> + return 2;
> + }
> +
> + if (!strcmp(attr->name, "state")) {
> + sprintf(buffer, "%d\n", stav);
> + return strlen(buffer)+1;
> + }
> +
> + if (!strcmp(attr->name, "counter")) {
> + sprintf(buffer, "%d\n", packetcounter);
> + return strlen(buffer)+1;
> + }
> +
> + return 0;
> +}
> +
> +static ssize_t store(struct kobject *kobj, struct attribute *attr,
> + const char *buffer, size_t size)
> +{
> + int i;
> + char *cislo;
> + if (!strcmp(attr->name, "firewall")) {
> + if (size > 0 && buffer[0] == '1')
> + firewall = 1;
> + else
> + firewall = 0;
> + stav = 0;
> + return size;
> + }
> +
> + if (!strcmp(attr->name, "tcpport")) {
> + cislo = kmalloc(size+1, GFP_KERNEL);
> + for (i = 0; i < size; ++i)
> + cislo[i] = buffer[i];
> + cislo[size] = '\0';
> + if (kstrtoint(cislo, 10, &i) < 0)
> + i = -1;
> + if (i > 0 && i < 65536)
> + tcpport = htons(i);
> + kfree(cislo);
> + stav = 0;
> + return size;
> + }
> +
> + if (!strcmp(attr->name, "openers")) {
> + int udpport, i;
> + int *noveotviraky;
> + int *stareotviraky;
> + cislo = kmalloc(size+1, GFP_KERNEL);
> + for (i = 0; i < size; ++i)
> + cislo[i] = buffer[i];
> + cislo[size] = '\0';
> +
> + if (!strcmp(cislo, "reset") || !strcmp(cislo, "reset\n")) {
> + if (pocetotviraku)
> + kfree(otviraky);
> + pocetotviraku = 0;
> + }
> +
> + if (kstrtoint(cislo, 10, &i) < 0)
> + i = -1;
> + kfree(cislo);
> +
> + if (i > 0 && i < 65536 && (pocetotviraku == 0 ||
> + otviraky[pocetotviraku-1] != i))
> + udpport = htons(i);
> + else
> + return size;
> +
> + if (pocetotviraku < 10) {
> + noveotviraky = kmalloc((pocetotviraku+1)*sizeof(int),
> + GFP_KERNEL);
> +
> + for (i = 0; i < pocetotviraku; ++i)
> + noveotviraky[i] = otviraky[i];
> +
> + noveotviraky[pocetotviraku] = udpport;
> + stareotviraky = otviraky;
> + otviraky = noveotviraky;
> + if (pocetotviraku)
> + kfree(stareotviraky);
> +
> + ++pocetotviraku;
> + }
> + stav = 0;
> + return size;
> + }
> +
> + if (!strcmp(attr->name, "closers")) {
> + int udpport, i;
> + int *novezaviraky;
> + int *starezaviraky;
> + cislo = kmalloc(size+1, GFP_KERNEL);
> + for (i = 0; i < size; ++i)
> + cislo[i] = buffer[i];
> + cislo[size] = '\0';
> +
> + if (!strcmp(cislo, "reset") || !strcmp(cislo, "reset\n")) {
> + if (pocetzaviraku)
> + kfree(zaviraky);
> + pocetzaviraku = 0;
> + }
> +
> + if (kstrtoint(cislo, 10, &i) < 0)
> + i = -1;
> + kfree(cislo);
> +
> + if (i > 0 && i < 65536 && (pocetzaviraku == 0 ||
> + zaviraky[pocetzaviraku-1] != i))
> + udpport = htons(i);
> + else
> + return size;
> +
> + if (pocetzaviraku < 10) {
> + novezaviraky = kmalloc((pocetzaviraku+1)*sizeof(int),
> + GFP_KERNEL);
> +
> + for (i = 0; i < pocetzaviraku; ++i)
> + novezaviraky[i] = zaviraky[i];
> +
> + novezaviraky[pocetzaviraku] = udpport;
> + starezaviraky = zaviraky;
> + zaviraky = novezaviraky;
> + if (pocetzaviraku)
> + kfree(starezaviraky);
> +
> + ++pocetzaviraku;
> + }
> + stav = 0;
> + return size;
> + }
> +
> + if (!strcmp(attr->name, "open")) {
> + if (size > 0 && buffer[0] == '1')
> + open = 1;
> + else
> + open = 0;
> +
> + stav = 0;
> + return size;
> + }
> +
> + return 0;
> +}
> +
> +static const struct sysfs_ops so = {
> + .show = show,
> + .store = store,
> +};
> +
> +static struct kobj_type khid = {
> + .sysfs_ops = &so,
> +};
> +
> +static struct kobject kobj;
> +
> +static const struct attribute fw = {
> + .name = "firewall",
> + .mode = S_IRWXU,
> +};
> +
> +static const struct attribute opn = {
> + .name = "open",
> + .mode = S_IRWXU,
> +};
> +
> +static const struct attribute tcpp = {
> + .name = "tcpport",
> + .mode = S_IRWXU,
> +};
> +
> +static const struct attribute openers = {
> + .name = "openers",
> + .mode = S_IRWXU,
> +};
> +
> +static const struct attribute closers = {
> + .name = "closers",
> + .mode = S_IRWXU,
> +};
> +
> +static const struct attribute stat = {
> + .name = "state",
> + .mode = S_IRUSR,
> +};
> +
> +static const struct attribute counte = {
> + .name = "counter",
> + .mode = S_IRUSR,
> +};
> +
> +static int __init start(void)
> +{
> + if (inet_protos == 0x01234567) {
> + printk(KERN_WARNING "inet_protos parameter was not");
> + printk(KERN_WARNING " specified!\nread its value from");
> + printk(KERN_WARNING " System_map file file, and insert");
> + printk(KERN_WARNING " the module again!\n");
> + return -1;
> + }
> +
> + pocetotviraku = 0;
> + pocetzaviraku = 0;
> + stav = -1;
> + packetcounter = 0;
> + tcpport = 0;
> + open = 1;
> + firewall = 0;
> +
> + memset(&kobj, 0, sizeof(struct kobject));
> +
> + _inet_protos = (struct net_protocol **)inet_protos;
> +
> + kobject_init(&kobj, &khid);
> + if (kobject_add(&kobj, NULL, "tcpfirewall") < 0)
> + printk(KERN_ERR "kobject_add failed");
> +
> + if (sysfs_create_file(&kobj, &fw) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> + if (sysfs_create_file(&kobj, &opn) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> + if (sysfs_create_file(&kobj, &tcpp) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> + if (sysfs_create_file(&kobj, &openers) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> + if (sysfs_create_file(&kobj, &closers) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> + if (sysfs_create_file(&kobj, &stat) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> + if (sysfs_create_file(&kobj, &counte) < 0)
> + printk(KERN_ERR "sysfs_create_file failed");
> +
> + zalohatcp = _inet_protos[IPPROTO_TCP];
> + zalohaudp = _inet_protos[IPPROTO_UDP];
> + mytcp = *zalohatcp;
> + myudp = *zalohaudp;
> + tcpv4recv = mytcp.handler;
> + udprecv = myudp.handler;
> + mytcp.handler = tcpfirewall;
> + myudp.handler = udpcontroller;
> + _inet_protos[IPPROTO_TCP] = &mytcp;
> + _inet_protos[IPPROTO_UDP] = &myudp;
> + return 0;
> +}
> +
> +static void konec(void)
> +{
> + _inet_protos[IPPROTO_TCP] = zalohatcp;
> + _inet_protos[IPPROTO_UDP] = zalohaudp;
> +
> + if (pocetotviraku)
> + kfree(otviraky);
> + if (pocetzaviraku)
> + kfree(zaviraky);
> +
> + kobject_del(&kobj);
> +}
> +
> +module_init(start);
> +module_exit(konec);
> --
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--
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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