root/net/netfilter/nf_log.c

DEFINITIONS

1. nf_log_register
2. nf_log_unregister_pf
3. nf_log_unregister
4. nf_log_packet
5. seq_start
6. seq_next
7. seq_stop
8. seq_show
9. nflog_open
10. netfilter_log_init

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/seq_file.h>
#include <net/protocol.h>
#include <net/netfilter/nf_log.h>

#include "nf_internals.h"

/* Internal logging interface, which relies on the real
   LOG target modules */

#define NF_LOG_PREFIXLEN                128

static const struct nf_logger *nf_loggers[NFPROTO_NUMPROTO] __read_mostly;
static DEFINE_MUTEX(nf_log_mutex);

/* return EBUSY if somebody else is registered, EEXIST if the same logger
 * is registred, 0 on success. */
int nf_log_register(u_int8_t pf, const struct nf_logger *logger)
{
        int ret;

        if (pf >= ARRAY_SIZE(nf_loggers))
                return -EINVAL;

        /* Any setup of logging members must be done before
         * substituting pointer. */
        ret = mutex_lock_interruptible(&nf_log_mutex);
        if (ret < 0)
                return ret;

        if (!nf_loggers[pf])
                rcu_assign_pointer(nf_loggers[pf], logger);
        else if (nf_loggers[pf] == logger)
                ret = -EEXIST;
        else
                ret = -EBUSY;

        mutex_unlock(&nf_log_mutex);
        return ret;
}
EXPORT_SYMBOL(nf_log_register);

void nf_log_unregister_pf(u_int8_t pf)
{
        if (pf >= ARRAY_SIZE(nf_loggers))
                return;
        mutex_lock(&nf_log_mutex);
        rcu_assign_pointer(nf_loggers[pf], NULL);
        mutex_unlock(&nf_log_mutex);

        /* Give time to concurrent readers. */
        synchronize_rcu();
}
EXPORT_SYMBOL(nf_log_unregister_pf);

void nf_log_unregister(const struct nf_logger *logger)
{
        int i;

        mutex_lock(&nf_log_mutex);
        for (i = 0; i < ARRAY_SIZE(nf_loggers); i++) {
                if (nf_loggers[i] == logger)
                        rcu_assign_pointer(nf_loggers[i], NULL);
        }
        mutex_unlock(&nf_log_mutex);

        synchronize_rcu();
}
EXPORT_SYMBOL(nf_log_unregister);

void nf_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 *fmt, ...)
{
        va_list args;
        char prefix[NF_LOG_PREFIXLEN];
        const struct nf_logger *logger;

        rcu_read_lock();
        logger = rcu_dereference(nf_loggers[pf]);
        if (logger) {
                va_start(args, fmt);
                vsnprintf(prefix, sizeof(prefix), fmt, args);
                va_end(args);
                logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL(nf_log_packet);

#ifdef CONFIG_PROC_FS
static void *seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(RCU)
{
        rcu_read_lock();

        if (*pos >= ARRAY_SIZE(nf_loggers))
                return NULL;

        return pos;
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        (*pos)++;

        if (*pos >= ARRAY_SIZE(nf_loggers))
                return NULL;

        return pos;
}

static void seq_stop(struct seq_file *s, void *v)
        __releases(RCU)
{
        rcu_read_unlock();
}

static int seq_show(struct seq_file *s, void *v)
{
        loff_t *pos = v;
        const struct nf_logger *logger;

        logger = rcu_dereference(nf_loggers[*pos]);

        if (!logger)
                return seq_printf(s, "%2lld NONE\n", *pos);

        return seq_printf(s, "%2lld %s\n", *pos, logger->name);
}

static const struct seq_operations nflog_seq_ops = {
        .start  = seq_start,
        .next   = seq_next,
        .stop   = seq_stop,
        .show   = seq_show,
};

static int nflog_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &nflog_seq_ops);
}

static const struct file_operations nflog_file_ops = {
        .owner   = THIS_MODULE,
        .open    = nflog_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release,
};

#endif /* PROC_FS */


int __init netfilter_log_init(void)
{
#ifdef CONFIG_PROC_FS
        if (!proc_create("nf_log", S_IRUGO,
                         proc_net_netfilter, &nflog_file_ops))
                return -1;
#endif
        return 0;
}