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/* netfilter.c: look after the filters for various protocols.

 * Heavily influenced by the old firewall.c by David Bonn and Alan Cox.

 *

 * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any

 * way.

 *

 * Rusty Russell (C)2000 -- This code is GPL.

 *

 * February 2000: Modified by James Morris to have 1 queue per protocol.

 * 15-Mar-2000:   Added NF_REPEAT --RR.

 */

#include <linux/config.h>

#include <linux/netfilter.h>

#include <net/protocol.h>

#include <linux/init.h>

#include <linux/skbuff.h>

#include <linux/wait.h>

#include <linux/module.h>

#include <linux/interrupt.h>

#include <linux/if.h>

#include <linux/netdevice.h>

#include <linux/brlock.h>

#include <linux/inetdevice.h>

#include <net/sock.h>

#include <net/route.h>

#include <linux/ip.h>

#define __KERNEL_SYSCALLS__

#include <linux/unistd.h>

/* In this code, we can be waiting indefinitely for userspace to

 * service a packet if a hook returns NF_QUEUE.  We could keep a count

 * of skbuffs queued for userspace, and not deregister a hook unless

 * this is zero, but that sucks.  Now, we simply check when the

 * packets come back: if the hook is gone, the packet is discarded. */

#ifdef CONFIG_NETFILTER_DEBUG

#define NFDEBUG(format, args...)  printk(format , ## args)

#else

#define NFDEBUG(format, args...)

#endif

/* Sockopts only registered and called from user context, so

   BR_NETPROTO_LOCK would be overkill.  Also, [gs]etsockopt calls may

   sleep. */

static DECLARE_MUTEX(nf_sockopt_mutex);

struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];

static LIST_HEAD(nf_sockopts);

/*

 * A queue handler may be registered for each protocol.  Each is protected by

 * long term mutex.  The handler must provide an an outfn() to accept packets

 * for queueing and must reinject all packets it receives, no matter what.

 */

static struct nf_queue_handler_t {

        nf_queue_outfn_t outfn;

        void *data;

} queue_handler[NPROTO];

int nf_register_hook(struct nf_hook_ops *reg)

{

        struct list_head *i;

        br_write_lock_bh(BR_NETPROTO_LOCK);

        for (i = nf_hooks[reg->pf][reg->hooknum].next;

             i != &nf_hooks[reg->pf][reg->hooknum];

             i = i->next) {

                if (reg->priority < ((struct nf_hook_ops *)i)->priority)

                        break;

        }

        list_add(&reg->list, i->prev);

        br_write_unlock_bh(BR_NETPROTO_LOCK);

        return 0;

}

void nf_unregister_hook(struct nf_hook_ops *reg)

{

        br_write_lock_bh(BR_NETPROTO_LOCK);

        list_del(&reg->list);

        br_write_unlock_bh(BR_NETPROTO_LOCK);

}

/* Do exclusive ranges overlap? */

static inline int overlap(int min1, int max1, int min2, int max2)

{

        return max1 > min2 && min1 < max2;

}

/* Functions to register sockopt ranges (exclusive). */

int nf_register_sockopt(struct nf_sockopt_ops *reg)

{

        struct list_head *i;

        int ret = 0;

        if (down_interruptible(&nf_sockopt_mutex) != 0)

                return -EINTR;

        for (i = nf_sockopts.next; i != &nf_sockopts; i = i->next) {

                struct nf_sockopt_ops *ops = (struct nf_sockopt_ops *)i;

                if (ops->pf == reg->pf

                    && (overlap(ops->set_optmin, ops->set_optmax,

                                reg->set_optmin, reg->set_optmax)

                        || overlap(ops->get_optmin, ops->get_optmax,

                                   reg->get_optmin, reg->get_optmax))) {

                        NFDEBUG("nf_sock overlap: %u-%u/%u-%u v %u-%u/%u-%u\n",

                                ops->set_optmin, ops->set_optmax,

                                ops->get_optmin, ops->get_optmax,

                                reg->set_optmin, reg->set_optmax,

                                reg->get_optmin, reg->get_optmax);

                        ret = -EBUSY;

                        goto out;

                }

        }

        list_add(&reg->list, &nf_sockopts);

out:

        up(&nf_sockopt_mutex);

        return ret;

}

void nf_unregister_sockopt(struct nf_sockopt_ops *reg)

{

        /* No point being interruptible: we're probably in cleanup_module() */

 restart:

        down(&nf_sockopt_mutex);

        if (reg->use != 0) {

                /* To be woken by nf_sockopt call... */

                /* FIXME: Stuart Young's name appears gratuitously. */

                set_current_state(TASK_UNINTERRUPTIBLE);

                reg->cleanup_task = current;

                up(&nf_sockopt_mutex);

                schedule();

                goto restart;

        }

        list_del(&reg->list);

        up(&nf_sockopt_mutex);

}

#ifdef CONFIG_NETFILTER_DEBUG

#include <net/ip.h>

#include <net/route.h>

#include <net/tcp.h>

#include <linux/netfilter_ipv4.h>

static void debug_print_hooks_ip(unsigned int nf_debug)

{

        if (nf_debug & (1 << NF_IP_PRE_ROUTING)) {

                printk("PRE_ROUTING ");

                nf_debug ^= (1 << NF_IP_PRE_ROUTING);

        }

        if (nf_debug & (1 << NF_IP_LOCAL_IN)) {

                printk("LOCAL_IN ");

                nf_debug ^= (1 << NF_IP_LOCAL_IN);

        }

        if (nf_debug & (1 << NF_IP_FORWARD)) {

                printk("FORWARD ");

                nf_debug ^= (1 << NF_IP_FORWARD);

        }

        if (nf_debug & (1 << NF_IP_LOCAL_OUT)) {

                printk("LOCAL_OUT ");

                nf_debug ^= (1 << NF_IP_LOCAL_OUT);

        }

        if (nf_debug & (1 << NF_IP_POST_ROUTING)) {

                printk("POST_ROUTING ");

                nf_debug ^= (1 << NF_IP_POST_ROUTING);

        }

        if (nf_debug)

                printk("Crap bits: 0x%04X", nf_debug);

        printk("\n");

}

void nf_dump_skb(int pf, struct sk_buff *skb)

{

        printk("skb: pf=%i %s dev=%s len=%u\n",

               pf,

               skb->sk ? "(owned)" : "(unowned)",

               skb->dev ? skb->dev->name : "(no dev)",

               skb->len);

        switch (pf) {

        case PF_INET: {

                const struct iphdr *ip = skb->nh.iph;

                __u32 *opt = (__u32 *) (ip + 1);

                int opti;

                __u16 src_port = 0, dst_port = 0;

                if (ip->protocol == IPPROTO_TCP

                    || ip->protocol == IPPROTO_UDP) {

                        struct tcphdr *tcp=(struct tcphdr *)((__u32 *)ip+ip->ihl);

                        src_port = ntohs(tcp->source);

                        dst_port = ntohs(tcp->dest);

                }

                printk("PROTO=%d %u.%u.%u.%u:%hu %u.%u.%u.%u:%hu"

                       " L=%hu S=0x%2.2hX I=%hu F=0x%4.4hX T=%hu",

                       ip->protocol, NIPQUAD(ip->saddr),

                       src_port, NIPQUAD(ip->daddr),

                       dst_port,

                       ntohs(ip->tot_len), ip->tos, ntohs(ip->id),

                       ntohs(ip->frag_off), ip->ttl);

                for (opti = 0; opti < (ip->ihl - sizeof(struct iphdr) / 4); opti++)

                        printk(" O=0x%8.8X", *opt++);

                printk("\n");

        }

        }

}

void nf_debug_ip_local_deliver(struct sk_buff *skb)

{

        /* If it's a loopback packet, it must have come through

         * NF_IP_LOCAL_OUT, NF_IP_RAW_INPUT, NF_IP_PRE_ROUTING and

         * NF_IP_LOCAL_IN.  Otherwise, must have gone through

         * NF_IP_RAW_INPUT and NF_IP_PRE_ROUTING.  */

        if (!skb->dev) {

                printk("ip_local_deliver: skb->dev is NULL.\n");

        }

        else if (strcmp(skb->dev->name, "lo") == 0) {

                if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)

                                      | (1 << NF_IP_POST_ROUTING)

                                      | (1 << NF_IP_PRE_ROUTING)

                                      | (1 << NF_IP_LOCAL_IN))) {

                        printk("ip_local_deliver: bad loopback skb: ");

                        debug_print_hooks_ip(skb->nf_debug);

                        nf_dump_skb(PF_INET, skb);

                }

        }

        else {

                if (skb->nf_debug != ((1<<NF_IP_PRE_ROUTING)

                                      | (1<<NF_IP_LOCAL_IN))) {

                        printk("ip_local_deliver: bad non-lo skb: ");

                        debug_print_hooks_ip(skb->nf_debug);

                        nf_dump_skb(PF_INET, skb);

                }

        }

}

void nf_debug_ip_loopback_xmit(struct sk_buff *newskb)

{

        if (newskb->nf_debug != ((1 << NF_IP_LOCAL_OUT)

                                 | (1 << NF_IP_POST_ROUTING))) {

                printk("ip_dev_loopback_xmit: bad owned skb = %p: ",

                       newskb);

                debug_print_hooks_ip(newskb->nf_debug);

                nf_dump_skb(PF_INET, newskb);

        }

        /* Clear to avoid confusing input check */

        newskb->nf_debug = 0;

}

void nf_debug_ip_finish_output2(struct sk_buff *skb)

{

        /* If it's owned, it must have gone through the

         * NF_IP_LOCAL_OUT and NF_IP_POST_ROUTING.

         * Otherwise, must have gone through

         * NF_IP_PRE_ROUTING, NF_IP_FORWARD and NF_IP_POST_ROUTING.

         */

        if (skb->sk) {

                if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)

                                      | (1 << NF_IP_POST_ROUTING))) {

                        printk("ip_finish_output: bad owned skb = %p: ", skb);

                        debug_print_hooks_ip(skb->nf_debug);

                        nf_dump_skb(PF_INET, skb);

                }

        } else {

                if (skb->nf_debug != ((1 << NF_IP_PRE_ROUTING)

                                      | (1 << NF_IP_FORWARD)

                                      | (1 << NF_IP_POST_ROUTING))) {

                        /* Fragments, entunnelled packets, TCP RSTs

                           generated by ipt_REJECT will have no

                           owners, but still may be local */

                        if (skb->nf_debug != ((1 << NF_IP_LOCAL_OUT)

                                              | (1 << NF_IP_POST_ROUTING))){

                                printk("ip_finish_output:"

                                       " bad unowned skb = %p: ",skb);

                                debug_print_hooks_ip(skb->nf_debug);

                                nf_dump_skb(PF_INET, skb);

                        }

                }

        }

}

#endif /*CONFIG_NETFILTER_DEBUG*/

/* Call get/setsockopt() */

static int nf_sockopt(struct sock *sk, int pf, int val,

                      char *opt, int *len, int get)

{

        struct list_head *i;

        struct nf_sockopt_ops *ops;

        int ret;

        if (down_interruptible(&nf_sockopt_mutex) != 0)

                return -EINTR;

        for (i = nf_sockopts.next; i != &nf_sockopts; i = i->next) {

                ops = (struct nf_sockopt_ops *)i;

                if (ops->pf == pf) {

                        if (get) {

                                if (val >= ops->get_optmin

                                    && val < ops->get_optmax) {

                                        ops->use++;

                                        up(&nf_sockopt_mutex);

                                        ret = ops->get(sk, val, opt, len);

                                        goto out;

                                }

                        } else {

                                if (val >= ops->set_optmin

                                    && val < ops->set_optmax) {

                                        ops->use++;

                                        up(&nf_sockopt_mutex);

                                        ret = ops->set(sk, val, opt, *len);

                                        goto out;

                                }

                        }

                }

        }

        up(&nf_sockopt_mutex);

        return -ENOPROTOOPT;

 out:

        down(&nf_sockopt_mutex);

        ops->use--;

        if (ops->cleanup_task)

                wake_up_process(ops->cleanup_task);

        up(&nf_sockopt_mutex);

        return ret;

}

int nf_setsockopt(struct sock *sk, int pf, int val, char *opt,

                  int len)

{

        return nf_sockopt(sk, pf, val, opt, &len, 0);

}

int nf_getsockopt(struct sock *sk, int pf, int val, char *opt, int *len)

{

        return nf_sockopt(sk, pf, val, opt, len, 1);

}

static unsigned int nf_iterate(struct list_head *head,

                               struct sk_buff **skb,

                               int hook,

                               const struct net_device *indev,

                               const struct net_device *outdev,

                               struct list_head **i,

                               int (*okfn)(struct sk_buff *))

{

        for (*i = (*i)->next; *i != head; *i = (*i)->next) {

                struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;

                switch (elem->hook(hook, skb, indev, outdev, okfn)) {

                case NF_QUEUE:

                        return NF_QUEUE;

                case NF_STOLEN:

                        return NF_STOLEN;

                case NF_DROP:

                        return NF_DROP;

                case NF_REPEAT:

                        *i = (*i)->prev;

                        break;

#ifdef CONFIG_NETFILTER_DEBUG

                case NF_ACCEPT:

                        break;

                default:

                        NFDEBUG("Evil return from %p(%u).\n",

                                elem->hook, hook);

#endif

                }

        }

        return NF_ACCEPT;

}

int nf_register_queue_handler(int pf, nf_queue_outfn_t outfn, void *data)

{

        int ret;

        br_write_lock_bh(BR_NETPROTO_LOCK);

        if (queue_handler[pf].outfn)

                ret = -EBUSY;

        else {

                queue_handler[pf].outfn = outfn;

                queue_handler[pf].data = data;

                ret = 0;

        }

        br_write_unlock_bh(BR_NETPROTO_LOCK);

        return ret;

}

/* The caller must flush their queue before this */

int nf_unregister_queue_handler(int pf)

{

        br_write_lock_bh(BR_NETPROTO_LOCK);

        queue_handler[pf].outfn = NULL;

        queue_handler[pf].data = NULL;

        br_write_unlock_bh(BR_NETPROTO_LOCK);

        return 0;

}

/*

 * Any packet that leaves via this function must come back

 * through nf_reinject().

 */

static void nf_queue(struct sk_buff *skb,

                     struct list_head *elem,

                     int pf, unsigned int hook,

                     struct net_device *indev,

                     struct net_device *outdev,

                     int (*okfn)(struct sk_buff *))

{

        int status;

        struct nf_info *info;

        if (!queue_handler[pf].outfn) {

                kfree_skb(skb);

                return;

        }

        info = kmalloc(sizeof(*info), GFP_ATOMIC);

        if (!info) {

                if (net_ratelimit())

                        printk(KERN_ERR "OOM queueing packet %p\n",

                               skb);

                kfree_skb(skb);

                return;

        }

        *info = (struct nf_info) {

                (struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };

        /* Bump dev refs so they don't vanish while packet is out */

        if (indev) dev_hold(indev);

        if (outdev) dev_hold(outdev);

        status = queue_handler[pf].outfn(skb, info, queue_handler[pf].data);

        if (status < 0) {

                /* James M doesn't say fuck enough. */

                if (indev) dev_put(indev);

                if (outdev) dev_put(outdev);

                kfree(info);

                kfree_skb(skb);

                return;

        }

}

int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,

                 struct net_device *indev,

                 struct net_device *outdev,

                 int (*okfn)(struct sk_buff *))

{

        struct list_head *elem;

        unsigned int verdict;

        int ret = 0;

        /* This stopgap cannot be removed until all the hooks are audited. */

        if (skb_is_nonlinear(skb) && skb_linearize(skb, GFP_ATOMIC) != 0) {

                kfree_skb(skb);

                return -ENOMEM;

        }

        if (skb->ip_summed == CHECKSUM_HW) {

                if (outdev == NULL) {

                        skb->ip_summed = CHECKSUM_NONE;

                } else {

                        skb_checksum_help(skb);

                }

        }

        /* We may already have this, but read-locks nest anyway */

        br_read_lock_bh(BR_NETPROTO_LOCK);

#ifdef CONFIG_NETFILTER_DEBUG

        if (skb->nf_debug & (1 << hook)) {

                printk("nf_hook: hook %i already set.\n", hook);

                nf_dump_skb(pf, skb);

        }

        skb->nf_debug |= (1 << hook);

#endif

        elem = &nf_hooks[pf][hook];

        verdict = nf_iterate(&nf_hooks[pf][hook], &skb, hook, indev,

                             outdev, &elem, okfn);

        if (verdict == NF_QUEUE) {

                NFDEBUG("nf_hook: Verdict = QUEUE.\n");

                nf_queue(skb, elem, pf, hook, indev, outdev, okfn);

        }

        switch (verdict) {

        case NF_ACCEPT:

                ret = okfn(skb);

                break;

        case NF_DROP:

                kfree_skb(skb);

                ret = -EPERM;

                break;

        }

        br_read_unlock_bh(BR_NETPROTO_LOCK);

        return ret;

}

void nf_reinject(struct sk_buff *skb, struct nf_info *info,

                 unsigned int verdict)

{

        struct list_head *elem = &info->elem->list;

        struct list_head *i;

        /* We don't have BR_NETPROTO_LOCK here */

        br_read_lock_bh(BR_NETPROTO_LOCK);

        for (i = nf_hooks[info->pf][info->hook].next; i != elem; i = i->next) {

                if (i == &nf_hooks[info->pf][info->hook]) {

                        /* The module which sent it to userspace is gone. */

                        NFDEBUG("%s: module disappeared, dropping packet.\n",

                                 __FUNCTION__);

                        verdict = NF_DROP;

                        break;

                }

        }

        /* Continue traversal iff userspace said ok... */

        if (verdict == NF_REPEAT) {

                elem = elem->prev;

                verdict = NF_ACCEPT;

        }

        if (verdict == NF_ACCEPT) {

                verdict = nf_iterate(&nf_hooks[info->pf][info->hook],

                                     &skb, info->hook,

                                     info->indev, info->outdev, &elem,

                                     info->okfn);

        }

        switch (verdict) {

        case NF_ACCEPT:

                info->okfn(skb);

                break;

        case NF_QUEUE:

                nf_queue(skb, elem, info->pf, info->hook,

                         info->indev, info->outdev, info->okfn);

                break;

        case NF_DROP:

                kfree_skb(skb);

                break;

        }

        br_read_unlock_bh(BR_NETPROTO_LOCK);

        /* Release those devices we held, or Alexey will kill me. */

        if (info->indev) dev_put(info->indev);

        if (info->outdev) dev_put(info->outdev);

        kfree(info);

        return;

}

#ifdef CONFIG_INET

/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */

int ip_route_me_harder(struct sk_buff **pskb)

{

        struct iphdr *iph = (*pskb)->nh.iph;

        struct rtable *rt;

        struct rt_key key = {};

        struct dst_entry *odst;

        unsigned int hh_len;

        /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause

         * packets with foreign saddr to be appear on the NF_IP_LOCAL_OUT hook.

         */

        if (inet_addr_type(iph->saddr) == RTN_LOCAL) {

                key.dst = iph->daddr;

                key.src = iph->saddr;

                key.oif = (*pskb)->sk ? (*pskb)->sk->bound_dev_if : 0;

                key.tos = RT_TOS(iph->tos);

#ifdef CONFIG_IP_ROUTE_FWMARK

                key.fwmark = (*pskb)->nfmark;

#endif

                if (ip_route_output_key(&rt, &key) != 0)

                        return -1;

                /* Drop old route. */

                dst_release((*pskb)->dst);

                (*pskb)->dst = &rt->u.dst;

        } else {

                /* non-local src, find valid iif to satisfy

                 * rp-filter when calling ip_route_input. */

                key.dst = iph->saddr;

                if (ip_route_output_key(&rt, &key) != 0)

                        return -1;

                odst = (*pskb)->dst;

                if (ip_route_input(*pskb, iph->daddr, iph->saddr,

                                   RT_TOS(iph->tos), rt->u.dst.dev) != 0) {

                        dst_release(&rt->u.dst);

                        return -1;

                }

                dst_release(&rt->u.dst);

                dst_release(odst);

        }

        if ((*pskb)->dst->error)

                return -1;

        /* Change in oif may mean change in hh_len. */

        hh_len = (*pskb)->dst->dev->hard_header_len;

        if (skb_headroom(*pskb) < hh_len) {

                struct sk_buff *nskb;

                nskb = skb_realloc_headroom(*pskb, hh_len);

                if (!nskb)

                        return -1;

                if ((*pskb)->sk)

                        skb_set_owner_w(nskb, (*pskb)->sk);

                kfree_skb(*pskb);

                *pskb = nskb;

        }

        return 0;

}

#endif /*CONFIG_INET*/

/* This does not belong here, but ipt_REJECT needs it if connection

   tracking in use: without this, connection may not be in hash table,

   and hence manufactured ICMP or RST packets will not be associated

   with it. */

void (*ip_ct_attach)(struct sk_buff *, struct nf_ct_info *);

void __init netfilter_init(void)

{

        int i, h;

        for (i = 0; i < NPROTO; i++) {

                for (h = 0; h < NF_MAX_HOOKS; h++)

                        INIT_LIST_HEAD(&nf_hooks[i][h]);

        }

}