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root/net/ipv6/netfilter/ip6t_LOG.c

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DEFINITIONS

This source file includes following definitions.
  1. dump_packet
  2. ip6t_log_packet
  3. log_tg6
  4. log_tg6_check
  5. log_tg6_init
  6. log_tg6_exit

/*
 * This is a module which is used for logging packets.
 */

/* (C) 2001 Jan Rekorajski <baggins@pld.org.pl>
 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/ip.h>
#include <linux/spinlock.h>
#include <linux/icmpv6.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <net/ipv6.h>
#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/netfilter/nf_log.h>

MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
MODULE_DESCRIPTION("Xtables: IPv6 packet logging to syslog");
MODULE_LICENSE("GPL");

struct in_device;
#include <net/route.h>
#include <linux/netfilter_ipv6/ip6t_LOG.h>

/* Use lock to serialize, so printks don't overlap */
static DEFINE_SPINLOCK(log_lock);

/* One level of recursion won't kill us */
static void dump_packet(const struct nf_loginfo *info,
                        const struct sk_buff *skb, unsigned int ip6hoff,
                        int recurse)
{
        u_int8_t currenthdr;
        int fragment;
        struct ipv6hdr _ip6h;
        const struct ipv6hdr *ih;
        unsigned int ptr;
        unsigned int hdrlen = 0;
        unsigned int logflags;

        if (info->type == NF_LOG_TYPE_LOG)
                logflags = info->u.log.logflags;
        else
                logflags = NF_LOG_MASK;

        ih = skb_header_pointer(skb, ip6hoff, sizeof(_ip6h), &_ip6h);
        if (ih == NULL) {
                printk("TRUNCATED");
                return;
        }

        /* Max length: 88 "SRC=0000.0000.0000.0000.0000.0000.0000.0000 DST=0000.0000.0000.0000.0000.0000.0000.0000 " */
        printk("SRC=" NIP6_FMT " DST=" NIP6_FMT " ", NIP6(ih->saddr), NIP6(ih->daddr));

        /* Max length: 44 "LEN=65535 TC=255 HOPLIMIT=255 FLOWLBL=FFFFF " */
        printk("LEN=%Zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
               ntohs(ih->payload_len) + sizeof(struct ipv6hdr),
               (ntohl(*(__be32 *)ih) & 0x0ff00000) >> 20,
               ih->hop_limit,
               (ntohl(*(__be32 *)ih) & 0x000fffff));

        fragment = 0;
        ptr = ip6hoff + sizeof(struct ipv6hdr);
        currenthdr = ih->nexthdr;
        while (currenthdr != NEXTHDR_NONE && ip6t_ext_hdr(currenthdr)) {
                struct ipv6_opt_hdr _hdr;
                const struct ipv6_opt_hdr *hp;

                hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
                if (hp == NULL) {
                        printk("TRUNCATED");
                        return;
                }

                /* Max length: 48 "OPT (...) " */
                if (logflags & IP6T_LOG_IPOPT)
                        printk("OPT ( ");

                switch (currenthdr) {
                case IPPROTO_FRAGMENT: {
                        struct frag_hdr _fhdr;
                        const struct frag_hdr *fh;

                        printk("FRAG:");
                        fh = skb_header_pointer(skb, ptr, sizeof(_fhdr),
                                                &_fhdr);
                        if (fh == NULL) {
                                printk("TRUNCATED ");
                                return;
                        }

                        /* Max length: 6 "65535 " */
                        printk("%u ", ntohs(fh->frag_off) & 0xFFF8);

                        /* Max length: 11 "INCOMPLETE " */
                        if (fh->frag_off & htons(0x0001))
                                printk("INCOMPLETE ");

                        printk("ID:%08x ", ntohl(fh->identification));

                        if (ntohs(fh->frag_off) & 0xFFF8)
                                fragment = 1;

                        hdrlen = 8;

                        break;
                }
                case IPPROTO_DSTOPTS:
                case IPPROTO_ROUTING:
                case IPPROTO_HOPOPTS:
                        if (fragment) {
                                if (logflags & IP6T_LOG_IPOPT)
                                        printk(")");
                                return;
                        }
                        hdrlen = ipv6_optlen(hp);
                        break;
                /* Max Length */
                case IPPROTO_AH:
                        if (logflags & IP6T_LOG_IPOPT) {
                                struct ip_auth_hdr _ahdr;
                                const struct ip_auth_hdr *ah;

                                /* Max length: 3 "AH " */
                                printk("AH ");

                                if (fragment) {
                                        printk(")");
                                        return;
                                }

                                ah = skb_header_pointer(skb, ptr, sizeof(_ahdr),
                                                        &_ahdr);
                                if (ah == NULL) {
                                        /*
                                         * Max length: 26 "INCOMPLETE [65535
                                         *  bytes] )"
                                         */
                                        printk("INCOMPLETE [%u bytes] )",
                                               skb->len - ptr);
                                        return;
                                }

                                /* Length: 15 "SPI=0xF1234567 */
                                printk("SPI=0x%x ", ntohl(ah->spi));

                        }

                        hdrlen = (hp->hdrlen+2)<<2;
                        break;
                case IPPROTO_ESP:
                        if (logflags & IP6T_LOG_IPOPT) {
                                struct ip_esp_hdr _esph;
                                const struct ip_esp_hdr *eh;

                                /* Max length: 4 "ESP " */
                                printk("ESP ");

                                if (fragment) {
                                        printk(")");
                                        return;
                                }

                                /*
                                 * Max length: 26 "INCOMPLETE [65535 bytes] )"
                                 */
                                eh = skb_header_pointer(skb, ptr, sizeof(_esph),
                                                        &_esph);
                                if (eh == NULL) {
                                        printk("INCOMPLETE [%u bytes] )",
                                               skb->len - ptr);
                                        return;
                                }

                                /* Length: 16 "SPI=0xF1234567 )" */
                                printk("SPI=0x%x )", ntohl(eh->spi) );

                        }
                        return;
                default:
                        /* Max length: 20 "Unknown Ext Hdr 255" */
                        printk("Unknown Ext Hdr %u", currenthdr);
                        return;
                }
                if (logflags & IP6T_LOG_IPOPT)
                        printk(") ");

                currenthdr = hp->nexthdr;
                ptr += hdrlen;
        }

        switch (currenthdr) {
        case IPPROTO_TCP: {
                struct tcphdr _tcph;
                const struct tcphdr *th;

                /* Max length: 10 "PROTO=TCP " */
                printk("PROTO=TCP ");

                if (fragment)
                        break;

                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                th = skb_header_pointer(skb, ptr, sizeof(_tcph), &_tcph);
                if (th == NULL) {
                        printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
                        return;
                }

                /* Max length: 20 "SPT=65535 DPT=65535 " */
                printk("SPT=%u DPT=%u ",
                       ntohs(th->source), ntohs(th->dest));
                /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
                if (logflags & IP6T_LOG_TCPSEQ)
                        printk("SEQ=%u ACK=%u ",
                               ntohl(th->seq), ntohl(th->ack_seq));
                /* Max length: 13 "WINDOW=65535 " */
                printk("WINDOW=%u ", ntohs(th->window));
                /* Max length: 9 "RES=0x3C " */
                printk("RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
                /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
                if (th->cwr)
                        printk("CWR ");
                if (th->ece)
                        printk("ECE ");
                if (th->urg)
                        printk("URG ");
                if (th->ack)
                        printk("ACK ");
                if (th->psh)
                        printk("PSH ");
                if (th->rst)
                        printk("RST ");
                if (th->syn)
                        printk("SYN ");
                if (th->fin)
                        printk("FIN ");
                /* Max length: 11 "URGP=65535 " */
                printk("URGP=%u ", ntohs(th->urg_ptr));

                if ((logflags & IP6T_LOG_TCPOPT)
                    && th->doff * 4 > sizeof(struct tcphdr)) {
                        u_int8_t _opt[60 - sizeof(struct tcphdr)];
                        const u_int8_t *op;
                        unsigned int i;
                        unsigned int optsize = th->doff * 4
                                               - sizeof(struct tcphdr);

                        op = skb_header_pointer(skb,
                                                ptr + sizeof(struct tcphdr),
                                                optsize, _opt);
                        if (op == NULL) {
                                printk("OPT (TRUNCATED)");
                                return;
                        }

                        /* Max length: 127 "OPT (" 15*4*2chars ") " */
                        printk("OPT (");
                        for (i =0; i < optsize; i++)
                                printk("%02X", op[i]);
                        printk(") ");
                }
                break;
        }
        case IPPROTO_UDP:
        case IPPROTO_UDPLITE: {
                struct udphdr _udph;
                const struct udphdr *uh;

                if (currenthdr == IPPROTO_UDP)
                        /* Max length: 10 "PROTO=UDP "     */
                        printk("PROTO=UDP " );
                else    /* Max length: 14 "PROTO=UDPLITE " */
                        printk("PROTO=UDPLITE ");

                if (fragment)
                        break;

                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                uh = skb_header_pointer(skb, ptr, sizeof(_udph), &_udph);
                if (uh == NULL) {
                        printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
                        return;
                }

                /* Max length: 20 "SPT=65535 DPT=65535 " */
                printk("SPT=%u DPT=%u LEN=%u ",
                       ntohs(uh->source), ntohs(uh->dest),
                       ntohs(uh->len));
                break;
        }
        case IPPROTO_ICMPV6: {
                struct icmp6hdr _icmp6h;
                const struct icmp6hdr *ic;

                /* Max length: 13 "PROTO=ICMPv6 " */
                printk("PROTO=ICMPv6 ");

                if (fragment)
                        break;

                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                ic = skb_header_pointer(skb, ptr, sizeof(_icmp6h), &_icmp6h);
                if (ic == NULL) {
                        printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
                        return;
                }

                /* Max length: 18 "TYPE=255 CODE=255 " */
                printk("TYPE=%u CODE=%u ", ic->icmp6_type, ic->icmp6_code);

                switch (ic->icmp6_type) {
                case ICMPV6_ECHO_REQUEST:
                case ICMPV6_ECHO_REPLY:
                        /* Max length: 19 "ID=65535 SEQ=65535 " */
                        printk("ID=%u SEQ=%u ",
                                ntohs(ic->icmp6_identifier),
                                ntohs(ic->icmp6_sequence));
                        break;
                case ICMPV6_MGM_QUERY:
                case ICMPV6_MGM_REPORT:
                case ICMPV6_MGM_REDUCTION:
                        break;

                case ICMPV6_PARAMPROB:
                        /* Max length: 17 "POINTER=ffffffff " */
                        printk("POINTER=%08x ", ntohl(ic->icmp6_pointer));
                        /* Fall through */
                case ICMPV6_DEST_UNREACH:
                case ICMPV6_PKT_TOOBIG:
                case ICMPV6_TIME_EXCEED:
                        /* Max length: 3+maxlen */
                        if (recurse) {
                                printk("[");
                                dump_packet(info, skb, ptr + sizeof(_icmp6h),
                                            0);
                                printk("] ");
                        }

                        /* Max length: 10 "MTU=65535 " */
                        if (ic->icmp6_type == ICMPV6_PKT_TOOBIG)
                                printk("MTU=%u ", ntohl(ic->icmp6_mtu));
                }
                break;
        }
        /* Max length: 10 "PROTO=255 " */
        default:
                printk("PROTO=%u ", currenthdr);
        }

        /* Max length: 15 "UID=4294967295 " */
        if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) {
                read_lock_bh(&skb->sk->sk_callback_lock);
                if (skb->sk->sk_socket && skb->sk->sk_socket->file)
                        printk("UID=%u GID=%u ",
                                skb->sk->sk_socket->file->f_uid,
                                skb->sk->sk_socket->file->f_gid);
                read_unlock_bh(&skb->sk->sk_callback_lock);
        }

        /* Max length: 16 "MARK=0xFFFFFFFF " */
        if (!recurse && skb->mark)
                printk("MARK=0x%x ", skb->mark);
}

static struct nf_loginfo default_loginfo = {
        .type   = NF_LOG_TYPE_LOG,
        .u = {
                .log = {
                        .level    = 0,
                        .logflags = NF_LOG_MASK,
                },
        },
};

static void
ip6t_log_packet(u_int8_t pf,
                unsigned int hooknum,
                const struct sk_buff *skb,
                const struct net_device *in,
                const struct net_device *out,
                const struct nf_loginfo *loginfo,
                const char *prefix)
{
        if (!loginfo)
                loginfo = &default_loginfo;

        spin_lock_bh(&log_lock);
        printk("<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
                prefix,
                in ? in->name : "",
                out ? out->name : "");
        if (in && !out) {
                unsigned int len;
                /* MAC logging for input chain only. */
                printk("MAC=");
                if (skb->dev && (len = skb->dev->hard_header_len) &&
                    skb->mac_header != skb->network_header) {
                        const unsigned char *p = skb_mac_header(skb);
                        int i;

                        if (skb->dev->type == ARPHRD_SIT &&
                            (p -= ETH_HLEN) < skb->head)
                                p = NULL;

                        if (p != NULL) {
                                for (i = 0; i < len; i++)
                                        printk("%02x%s", p[i],
                                               i == len - 1 ? "" : ":");
                        }
                        printk(" ");

                        if (skb->dev->type == ARPHRD_SIT) {
                                const struct iphdr *iph =
                                        (struct iphdr *)skb_mac_header(skb);
                                printk("TUNNEL=%u.%u.%u.%u->%u.%u.%u.%u ",
                                       NIPQUAD(iph->saddr),
                                       NIPQUAD(iph->daddr));
                        }
                } else
                        printk(" ");
        }

        dump_packet(loginfo, skb, skb_network_offset(skb), 1);
        printk("\n");
        spin_unlock_bh(&log_lock);
}

static unsigned int
log_tg6(struct sk_buff *skb, const struct xt_target_param *par)
{
        const struct ip6t_log_info *loginfo = par->targinfo;
        struct nf_loginfo li;

        li.type = NF_LOG_TYPE_LOG;
        li.u.log.level = loginfo->level;
        li.u.log.logflags = loginfo->logflags;

        ip6t_log_packet(NFPROTO_IPV6, par->hooknum, skb, par->in, par->out,
                        &li, loginfo->prefix);
        return XT_CONTINUE;
}


static bool log_tg6_check(const struct xt_tgchk_param *par)
{
        const struct ip6t_log_info *loginfo = par->targinfo;

        if (loginfo->level >= 8) {
                pr_debug("LOG: level %u >= 8\n", loginfo->level);
                return false;
        }
        if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
                pr_debug("LOG: prefix term %i\n",
                         loginfo->prefix[sizeof(loginfo->prefix)-1]);
                return false;
        }
        return true;
}

static struct xt_target log_tg6_reg __read_mostly = {
        .name           = "LOG",
        .family         = NFPROTO_IPV6,
        .target         = log_tg6,
        .targetsize     = sizeof(struct ip6t_log_info),
        .checkentry     = log_tg6_check,
        .me             = THIS_MODULE,
};

static const struct nf_logger ip6t_logger = {
        .name           = "ip6t_LOG",
        .logfn          = &ip6t_log_packet,
        .me             = THIS_MODULE,
};

static int __init log_tg6_init(void)
{
        int ret;

        ret = xt_register_target(&log_tg6_reg);
        if (ret < 0)
                return ret;
        nf_log_register(NFPROTO_IPV6, &ip6t_logger);
        return 0;
}

static void __exit log_tg6_exit(void)
{
        nf_log_unregister(&ip6t_logger);
        xt_unregister_target(&log_tg6_reg);
}

module_init(log_tg6_init);
module_exit(log_tg6_exit);

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