| /* |
| * netfilter module for userspace packet logging daemons |
| * |
| * (C) 2000-2004 by Harald Welte <laforge@netfilter.org> |
| * (C) 1999-2001 Paul `Rusty' Russell |
| * (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. |
| * |
| * This module accepts two parameters: |
| * |
| * nlbufsiz: |
| * The parameter specifies how big the buffer for each netlink multicast |
| * group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will |
| * get accumulated in the kernel until they are sent to userspace. It is |
| * NOT possible to allocate more than 128kB, and it is strongly discouraged, |
| * because atomically allocating 128kB inside the network rx softirq is not |
| * reliable. Please also keep in mind that this buffer size is allocated for |
| * each nlgroup you are using, so the total kernel memory usage increases |
| * by that factor. |
| * |
| * Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since |
| * nlbufsiz is used with alloc_skb, which adds another |
| * sizeof(struct skb_shared_info). Use NLMSG_GOODSIZE instead. |
| * |
| * flushtimeout: |
| * Specify, after how many hundredths of a second the queue should be |
| * flushed even if it is not full yet. |
| */ |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #include <linux/module.h> |
| #include <linux/spinlock.h> |
| #include <linux/socket.h> |
| #include <linux/slab.h> |
| #include <linux/skbuff.h> |
| #include <linux/kernel.h> |
| #include <linux/timer.h> |
| #include <linux/netlink.h> |
| #include <linux/netdevice.h> |
| #include <linux/mm.h> |
| #include <linux/moduleparam.h> |
| #include <linux/netfilter.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter_ipv4/ipt_ULOG.h> |
| #include <net/netfilter/nf_log.h> |
| #include <net/sock.h> |
| #include <linux/bitops.h> |
| #include <asm/unaligned.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); |
| MODULE_DESCRIPTION("Xtables: packet logging to netlink using ULOG"); |
| MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG); |
| |
| #define ULOG_NL_EVENT 111 /* Harald's favorite number */ |
| #define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */ |
| |
| static unsigned int nlbufsiz = NLMSG_GOODSIZE; |
| module_param(nlbufsiz, uint, 0400); |
| MODULE_PARM_DESC(nlbufsiz, "netlink buffer size"); |
| |
| static unsigned int flushtimeout = 10; |
| module_param(flushtimeout, uint, 0600); |
| MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)"); |
| |
| static bool nflog = true; |
| module_param(nflog, bool, 0400); |
| MODULE_PARM_DESC(nflog, "register as internal netfilter logging module"); |
| |
| /* global data structures */ |
| |
| typedef struct { |
| unsigned int qlen; /* number of nlmsgs' in the skb */ |
| struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */ |
| struct sk_buff *skb; /* the pre-allocated skb */ |
| struct timer_list timer; /* the timer function */ |
| } ulog_buff_t; |
| |
| static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */ |
| |
| static struct sock *nflognl; /* our socket */ |
| static DEFINE_SPINLOCK(ulog_lock); /* spinlock */ |
| |
| /* send one ulog_buff_t to userspace */ |
| static void ulog_send(unsigned int nlgroupnum) |
| { |
| ulog_buff_t *ub = &ulog_buffers[nlgroupnum]; |
| |
| if (timer_pending(&ub->timer)) { |
| pr_debug("ulog_send: timer was pending, deleting\n"); |
| del_timer(&ub->timer); |
| } |
| |
| if (!ub->skb) { |
| pr_debug("ulog_send: nothing to send\n"); |
| return; |
| } |
| |
| /* last nlmsg needs NLMSG_DONE */ |
| if (ub->qlen > 1) |
| ub->lastnlh->nlmsg_type = NLMSG_DONE; |
| |
| NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1; |
| pr_debug("throwing %d packets to netlink group %u\n", |
| ub->qlen, nlgroupnum + 1); |
| netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC); |
| |
| ub->qlen = 0; |
| ub->skb = NULL; |
| ub->lastnlh = NULL; |
| } |
| |
| |
| /* timer function to flush queue in flushtimeout time */ |
| static void ulog_timer(unsigned long data) |
| { |
| pr_debug("timer function called, calling ulog_send\n"); |
| |
| /* lock to protect against somebody modifying our structure |
| * from ipt_ulog_target at the same time */ |
| spin_lock_bh(&ulog_lock); |
| ulog_send(data); |
| spin_unlock_bh(&ulog_lock); |
| } |
| |
| static struct sk_buff *ulog_alloc_skb(unsigned int size) |
| { |
| struct sk_buff *skb; |
| unsigned int n; |
| |
| /* alloc skb which should be big enough for a whole |
| * multipart message. WARNING: has to be <= 131000 |
| * due to slab allocator restrictions */ |
| |
| n = max(size, nlbufsiz); |
| skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN); |
| if (!skb) { |
| if (n > size) { |
| /* try to allocate only as much as we need for |
| * current packet */ |
| |
| skb = alloc_skb(size, GFP_ATOMIC); |
| if (!skb) |
| pr_debug("cannot even allocate %ub\n", size); |
| } |
| } |
| |
| return skb; |
| } |
| |
| static void ipt_ulog_packet(unsigned int hooknum, |
| const struct sk_buff *skb, |
| const struct net_device *in, |
| const struct net_device *out, |
| const struct ipt_ulog_info *loginfo, |
| const char *prefix) |
| { |
| ulog_buff_t *ub; |
| ulog_packet_msg_t *pm; |
| size_t size, copy_len; |
| struct nlmsghdr *nlh; |
| struct timeval tv; |
| |
| /* ffs == find first bit set, necessary because userspace |
| * is already shifting groupnumber, but we need unshifted. |
| * ffs() returns [1..32], we need [0..31] */ |
| unsigned int groupnum = ffs(loginfo->nl_group) - 1; |
| |
| /* calculate the size of the skb needed */ |
| if (loginfo->copy_range == 0 || loginfo->copy_range > skb->len) |
| copy_len = skb->len; |
| else |
| copy_len = loginfo->copy_range; |
| |
| size = NLMSG_SPACE(sizeof(*pm) + copy_len); |
| |
| ub = &ulog_buffers[groupnum]; |
| |
| spin_lock_bh(&ulog_lock); |
| |
| if (!ub->skb) { |
| if (!(ub->skb = ulog_alloc_skb(size))) |
| goto alloc_failure; |
| } else if (ub->qlen >= loginfo->qthreshold || |
| size > skb_tailroom(ub->skb)) { |
| /* either the queue len is too high or we don't have |
| * enough room in nlskb left. send it to userspace. */ |
| |
| ulog_send(groupnum); |
| |
| if (!(ub->skb = ulog_alloc_skb(size))) |
| goto alloc_failure; |
| } |
| |
| pr_debug("qlen %d, qthreshold %Zu\n", ub->qlen, loginfo->qthreshold); |
| |
| nlh = nlmsg_put(ub->skb, 0, ub->qlen, ULOG_NL_EVENT, |
| sizeof(*pm)+copy_len, 0); |
| if (!nlh) { |
| pr_debug("error during nlmsg_put\n"); |
| goto out_unlock; |
| } |
| ub->qlen++; |
| |
| pm = nlmsg_data(nlh); |
| |
| /* We might not have a timestamp, get one */ |
| if (skb->tstamp.tv64 == 0) |
| __net_timestamp((struct sk_buff *)skb); |
| |
| /* copy hook, prefix, timestamp, payload, etc. */ |
| pm->data_len = copy_len; |
| tv = ktime_to_timeval(skb->tstamp); |
| put_unaligned(tv.tv_sec, &pm->timestamp_sec); |
| put_unaligned(tv.tv_usec, &pm->timestamp_usec); |
| put_unaligned(skb->mark, &pm->mark); |
| pm->hook = hooknum; |
| if (prefix != NULL) |
| strncpy(pm->prefix, prefix, sizeof(pm->prefix)); |
| else if (loginfo->prefix[0] != '\0') |
| strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix)); |
| else |
| *(pm->prefix) = '\0'; |
| |
| if (in && in->hard_header_len > 0 && |
| skb->mac_header != skb->network_header && |
| in->hard_header_len <= ULOG_MAC_LEN) { |
| memcpy(pm->mac, skb_mac_header(skb), in->hard_header_len); |
| pm->mac_len = in->hard_header_len; |
| } else |
| pm->mac_len = 0; |
| |
| if (in) |
| strncpy(pm->indev_name, in->name, sizeof(pm->indev_name)); |
| else |
| pm->indev_name[0] = '\0'; |
| |
| if (out) |
| strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name)); |
| else |
| pm->outdev_name[0] = '\0'; |
| |
| /* copy_len <= skb->len, so can't fail. */ |
| if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0) |
| BUG(); |
| |
| /* check if we are building multi-part messages */ |
| if (ub->qlen > 1) |
| ub->lastnlh->nlmsg_flags |= NLM_F_MULTI; |
| |
| ub->lastnlh = nlh; |
| |
| /* if timer isn't already running, start it */ |
| if (!timer_pending(&ub->timer)) { |
| ub->timer.expires = jiffies + flushtimeout * HZ / 100; |
| add_timer(&ub->timer); |
| } |
| |
| /* if threshold is reached, send message to userspace */ |
| if (ub->qlen >= loginfo->qthreshold) { |
| if (loginfo->qthreshold > 1) |
| nlh->nlmsg_type = NLMSG_DONE; |
| ulog_send(groupnum); |
| } |
| out_unlock: |
| spin_unlock_bh(&ulog_lock); |
| |
| return; |
| |
| alloc_failure: |
| pr_debug("Error building netlink message\n"); |
| spin_unlock_bh(&ulog_lock); |
| } |
| |
| static unsigned int |
| ulog_tg(struct sk_buff *skb, const struct xt_action_param *par) |
| { |
| ipt_ulog_packet(par->hooknum, skb, par->in, par->out, |
| par->targinfo, NULL); |
| return XT_CONTINUE; |
| } |
| |
| static void ipt_logfn(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 *li, |
| const char *prefix) |
| { |
| struct ipt_ulog_info loginfo; |
| |
| if (!li || li->type != NF_LOG_TYPE_ULOG) { |
| loginfo.nl_group = ULOG_DEFAULT_NLGROUP; |
| loginfo.copy_range = 0; |
| loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD; |
| loginfo.prefix[0] = '\0'; |
| } else { |
| loginfo.nl_group = li->u.ulog.group; |
| loginfo.copy_range = li->u.ulog.copy_len; |
| loginfo.qthreshold = li->u.ulog.qthreshold; |
| strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix)); |
| } |
| |
| ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix); |
| } |
| |
| static int ulog_tg_check(const struct xt_tgchk_param *par) |
| { |
| const struct ipt_ulog_info *loginfo = par->targinfo; |
| |
| if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') { |
| pr_debug("prefix not null-terminated\n"); |
| return -EINVAL; |
| } |
| if (loginfo->qthreshold > ULOG_MAX_QLEN) { |
| pr_debug("queue threshold %Zu > MAX_QLEN\n", |
| loginfo->qthreshold); |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| #ifdef CONFIG_COMPAT |
| struct compat_ipt_ulog_info { |
| compat_uint_t nl_group; |
| compat_size_t copy_range; |
| compat_size_t qthreshold; |
| char prefix[ULOG_PREFIX_LEN]; |
| }; |
| |
| static void ulog_tg_compat_from_user(void *dst, const void *src) |
| { |
| const struct compat_ipt_ulog_info *cl = src; |
| struct ipt_ulog_info l = { |
| .nl_group = cl->nl_group, |
| .copy_range = cl->copy_range, |
| .qthreshold = cl->qthreshold, |
| }; |
| |
| memcpy(l.prefix, cl->prefix, sizeof(l.prefix)); |
| memcpy(dst, &l, sizeof(l)); |
| } |
| |
| static int ulog_tg_compat_to_user(void __user *dst, const void *src) |
| { |
| const struct ipt_ulog_info *l = src; |
| struct compat_ipt_ulog_info cl = { |
| .nl_group = l->nl_group, |
| .copy_range = l->copy_range, |
| .qthreshold = l->qthreshold, |
| }; |
| |
| memcpy(cl.prefix, l->prefix, sizeof(cl.prefix)); |
| return copy_to_user(dst, &cl, sizeof(cl)) ? -EFAULT : 0; |
| } |
| #endif /* CONFIG_COMPAT */ |
| |
| static struct xt_target ulog_tg_reg __read_mostly = { |
| .name = "ULOG", |
| .family = NFPROTO_IPV4, |
| .target = ulog_tg, |
| .targetsize = sizeof(struct ipt_ulog_info), |
| .checkentry = ulog_tg_check, |
| #ifdef CONFIG_COMPAT |
| .compatsize = sizeof(struct compat_ipt_ulog_info), |
| .compat_from_user = ulog_tg_compat_from_user, |
| .compat_to_user = ulog_tg_compat_to_user, |
| #endif |
| .me = THIS_MODULE, |
| }; |
| |
| static struct nf_logger ipt_ulog_logger __read_mostly = { |
| .name = "ipt_ULOG", |
| .logfn = ipt_logfn, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init ulog_tg_init(void) |
| { |
| int ret, i; |
| |
| pr_debug("init module\n"); |
| |
| if (nlbufsiz > 128*1024) { |
| pr_warning("Netlink buffer has to be <= 128kB\n"); |
| return -EINVAL; |
| } |
| |
| /* initialize ulog_buffers */ |
| for (i = 0; i < ULOG_MAXNLGROUPS; i++) |
| setup_timer(&ulog_buffers[i].timer, ulog_timer, i); |
| |
| nflognl = netlink_kernel_create(&init_net, |
| NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL, |
| NULL, THIS_MODULE); |
| if (!nflognl) |
| return -ENOMEM; |
| |
| ret = xt_register_target(&ulog_tg_reg); |
| if (ret < 0) { |
| netlink_kernel_release(nflognl); |
| return ret; |
| } |
| if (nflog) |
| nf_log_register(NFPROTO_IPV4, &ipt_ulog_logger); |
| |
| return 0; |
| } |
| |
| static void __exit ulog_tg_exit(void) |
| { |
| ulog_buff_t *ub; |
| int i; |
| |
| pr_debug("cleanup_module\n"); |
| |
| if (nflog) |
| nf_log_unregister(&ipt_ulog_logger); |
| xt_unregister_target(&ulog_tg_reg); |
| netlink_kernel_release(nflognl); |
| |
| /* remove pending timers and free allocated skb's */ |
| for (i = 0; i < ULOG_MAXNLGROUPS; i++) { |
| ub = &ulog_buffers[i]; |
| if (timer_pending(&ub->timer)) { |
| pr_debug("timer was pending, deleting\n"); |
| del_timer(&ub->timer); |
| } |
| |
| if (ub->skb) { |
| kfree_skb(ub->skb); |
| ub->skb = NULL; |
| } |
| } |
| } |
| |
| module_init(ulog_tg_init); |
| module_exit(ulog_tg_exit); |