net/netfilter/nf_log.c

   1 #include <linux/config.h>
   2 #include <linux/kernel.h>
   3 #include <linux/init.h>
   4 #include <linux/module.h>
   5 #include <linux/proc_fs.h>
   6 #include <linux/skbuff.h>
   7 #include <linux/netfilter.h>
   8 #include <net/protocol.h>
   9
  10 #include "nf_internals.h"
  11
  12 /* Internal logging interface, which relies on the real
  13    LOG target modules */
  14
  15 #define NF_LOG_PREFIXLEN                128
  16
  17 static struct nf_logger *nf_logging[NPROTO]; /* = NULL */
  18 static DEFINE_SPINLOCK(nf_log_lock);
  19
  20 int nf_log_register(int pf, struct nf_logger *logger)
  21 {
  22         int ret = -EBUSY;
  23
  24         /* Any setup of logging members must be done before
  25          * substituting pointer. */
  26         spin_lock(&nf_log_lock);
  27         if (!nf_logging[pf]) {
  28                 rcu_assign_pointer(nf_logging[pf], logger);
  29                 ret = 0;
  30         }
  31         spin_unlock(&nf_log_lock);
  32         return ret;
  33 }
  34 EXPORT_SYMBOL(nf_log_register);
  35
  36 void nf_log_unregister_pf(int pf)
  37 {
  38         spin_lock(&nf_log_lock);
  39         nf_logging[pf] = NULL;
  40         spin_unlock(&nf_log_lock);
  41
  42         /* Give time to concurrent readers. */
  43         synchronize_net();
  44 }
  45 EXPORT_SYMBOL(nf_log_unregister_pf);
  46
  47 void nf_log_unregister_logger(struct nf_logger *logger)
  48 {
  49         int i;
  50
  51         spin_lock(&nf_log_lock);
  52         for (i = 0; i < NPROTO; i++) {
  53                 if (nf_logging[i] == logger)
  54                         nf_logging[i] = NULL;
  55         }
  56         spin_unlock(&nf_log_lock);
  57
  58         synchronize_net();
  59 }
  60 EXPORT_SYMBOL(nf_log_unregister_logger);
  61
  62 void nf_log_packet(int pf,
  63                    unsigned int hooknum,
  64                    const struct sk_buff *skb,
  65                    const struct net_device *in,
  66                    const struct net_device *out,
  67                    struct nf_loginfo *loginfo,
  68                    const char *fmt, ...)
  69 {
  70         va_list args;
  71         char prefix[NF_LOG_PREFIXLEN];
  72         struct nf_logger *logger;
  73
  74         rcu_read_lock();
  75         logger = rcu_dereference(nf_logging[pf]);
  76         if (logger) {
  77                 va_start(args, fmt);
  78                 vsnprintf(prefix, sizeof(prefix), fmt, args);
  79                 va_end(args);
  80                 /* We must read logging before nf_logfn[pf] */
  81                 logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
  82         } else if (net_ratelimit()) {
  83                 printk(KERN_WARNING "nf_log_packet: can\'t log since "
  84                        "no backend logging module loaded in! Please either "
  85                        "load one, or disable logging explicitly\n");
  86         }
  87         rcu_read_unlock();
  88 }
  89 EXPORT_SYMBOL(nf_log_packet);
  90
  91 #ifdef CONFIG_PROC_FS
  92 static void *seq_start(struct seq_file *seq, loff_t *pos)
  93 {
  94         rcu_read_lock();
  95
  96         if (*pos >= NPROTO)
  97                 return NULL;
  98
  99         return pos;
 100 }
 101
 102 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 103 {
 104         (*pos)++;
 105
 106         if (*pos >= NPROTO)
 107                 return NULL;
 108
 109         return pos;
 110 }
 111
 112 static void seq_stop(struct seq_file *s, void *v)
 113 {
 114         rcu_read_unlock();
 115 }
 116
 117 static int seq_show(struct seq_file *s, void *v)
 118 {
 119         loff_t *pos = v;
 120         const struct nf_logger *logger;
 121
 122         logger = rcu_dereference(nf_logging[*pos]);
 123
 124         if (!logger)
 125                 return seq_printf(s, "%2lld NONE\n", *pos);
 126
 127         return seq_printf(s, "%2lld %s\n", *pos, logger->name);
 128 }
 129
 130 static struct seq_operations nflog_seq_ops = {
 131         .start  = seq_start,
 132         .next   = seq_next,
 133         .stop   = seq_stop,
 134         .show   = seq_show,
 135 };
 136
 137 static int nflog_open(struct inode *inode, struct file *file)
 138 {
 139         return seq_open(file, &nflog_seq_ops);
 140 }
 141
 142 static struct file_operations nflog_file_ops = {
 143         .owner   = THIS_MODULE,
 144         .open    = nflog_open,
 145         .read    = seq_read,
 146         .llseek  = seq_lseek,
 147         .release = seq_release,
 148 };
 149
 150 #endif /* PROC_FS */
 151
 152
 153 int __init netfilter_log_init(void)
 154 {
 155 #ifdef CONFIG_PROC_FS
 156         struct proc_dir_entry *pde;
 157         pde = create_proc_entry("nf_log", S_IRUGO, proc_net_netfilter);
 158 #endif
 159         if (!pde)
 160                 return -1;
 161
 162         pde->proc_fops = &nflog_file_ops;
 163
 164         return 0;
 165 }