Messages in this thread | | | Date | Thu, 11 Aug 2011 17:13:17 -0700 | From | Randy Dunlap <> | Subject | Re: TCP port firewall controlled by UDP packets |
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On Fri, 12 Aug 2011 01:56:09 +0200 Tonda wrote:
Need more patch description & justification here, as well as Signed-off-by: <your name & email address>
> diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig > --- a/net/ipv4/Kconfig > +++ b/net/ipv4/Kconfig > @@ -624,3 +624,7 @@ > on the Internet. > > If unsure, say N. > + > +config TCPFIREWALL > + tristate "TCP Firewall controlled by UDP queries" > + depends on m
Why buildable only as a loadable module?
> 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)
can be static?
> +{ > + 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)
can be static?
> +{ > + 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); > +}
[snip]
> +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");
Break the printk() calls at newlines, please.
> + 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"); > +
All of these kobject_add() and sysfs_create_file() failures are not fatal errors?
> + 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); > --
Some of the function & variable names confuse me.
--- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***
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