net/netfilter/nf_log.c

   1 #include <linux/kernel.h>
   2 #include <linux/init.h>
   3 #include <linux/module.h>
   4 #include <linux/proc_fs.h>
   5 #include <linux/skbuff.h>
   6 #include <linux/netfilter.h>
   7 #include <linux/seq_file.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_loggers[NPROTO];
  18 static DEFINE_MUTEX(nf_log_mutex);
  19
  20 /* return EBUSY if somebody else is registered, EEXIST if the same logger
  21  * is registred, 0 on success. */
  22 int nf_log_register(int pf, struct nf_logger *logger)
  23 {
  24         int ret;
  25
  26         if (pf >= NPROTO)
  27                 return -EINVAL;
  28
  29         /* Any setup of logging members must be done before
  30          * substituting pointer. */
  31         ret = mutex_lock_interruptible(&nf_log_mutex);
  32         if (ret < 0)
  33                 return ret;
  34
  35         if (!nf_loggers[pf])
  36                 rcu_assign_pointer(nf_loggers[pf], logger);
  37         else if (nf_loggers[pf] == logger)
  38                 ret = -EEXIST;
  39         else
  40                 ret = -EBUSY;
  41
  42         mutex_unlock(&nf_log_mutex);
  43         return ret;
  44 }
  45 EXPORT_SYMBOL(nf_log_register);
  46
  47 void nf_log_unregister_pf(int pf)
  48 {
  49         if (pf >= NPROTO)
  50                 return;
  51         mutex_lock(&nf_log_mutex);
  52         rcu_assign_pointer(nf_loggers[pf], NULL);
  53         mutex_unlock(&nf_log_mutex);
  54
  55         /* Give time to concurrent readers. */
  56         synchronize_rcu();
  57 }
  58 EXPORT_SYMBOL(nf_log_unregister_pf);
  59
  60 void nf_log_unregister(struct nf_logger *logger)
  61 {
  62         int i;
  63
  64         mutex_lock(&nf_log_mutex);
  65         for (i = 0; i < NPROTO; i++) {
  66                 if (nf_loggers[i] == logger)
  67                         rcu_assign_pointer(nf_loggers[i], NULL);
  68         }
  69         mutex_unlock(&nf_log_mutex);
  70
  71         synchronize_rcu();
  72 }
  73 EXPORT_SYMBOL(nf_log_unregister);
  74
  75 void nf_log_packet(int pf,
  76                    unsigned int hooknum,
  77                    const struct sk_buff *skb,
  78                    const struct net_device *in,
  79                    const struct net_device *out,
  80                    struct nf_loginfo *loginfo,
  81                    const char *fmt, ...)
  82 {
  83         va_list args;
  84         char prefix[NF_LOG_PREFIXLEN];
  85         struct nf_logger *logger;
  86
  87         rcu_read_lock();
  88         logger = rcu_dereference(nf_loggers[pf]);
  89         if (logger) {
  90                 va_start(args, fmt);
  91                 vsnprintf(prefix, sizeof(prefix), fmt, args);
  92                 va_end(args);
  93                 /* We must read logging before nf_logfn[pf] */
  94                 logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
  95         } else if (net_ratelimit()) {
  96                 printk(KERN_WARNING "nf_log_packet: can\'t log since "
  97                        "no backend logging module loaded in! Please either "
  98                        "load one, or disable logging explicitly\n");
  99         }
 100         rcu_read_unlock();
 101 }
 102 EXPORT_SYMBOL(nf_log_packet);
 103
 104 #ifdef CONFIG_PROC_FS
 105 static void *seq_start(struct seq_file *seq, loff_t *pos)
 106 {
 107         rcu_read_lock();
 108
 109         if (*pos >= NPROTO)
 110                 return NULL;
 111
 112         return pos;
 113 }
 114
 115 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 116 {
 117         (*pos)++;
 118
 119         if (*pos >= NPROTO)
 120                 return NULL;
 121
 122         return pos;
 123 }
 124
 125 static void seq_stop(struct seq_file *s, void *v)
 126 {
 127         rcu_read_unlock();
 128 }
 129
 130 static int seq_show(struct seq_file *s, void *v)
 131 {
 132         loff_t *pos = v;
 133         const struct nf_logger *logger;
 134
 135         logger = rcu_dereference(nf_loggers[*pos]);
 136
 137         if (!logger)
 138                 return seq_printf(s, "%2lld NONE\n", *pos);
 139
 140         return seq_printf(s, "%2lld %s\n", *pos, logger->name);
 141 }
 142
 143 static const struct seq_operations nflog_seq_ops = {
 144         .start  = seq_start,
 145         .next   = seq_next,
 146         .stop   = seq_stop,
 147         .show   = seq_show,
 148 };
 149
 150 static int nflog_open(struct inode *inode, struct file *file)
 151 {
 152         return seq_open(file, &nflog_seq_ops);
 153 }
 154
 155 static const struct file_operations nflog_file_ops = {
 156         .owner   = THIS_MODULE,
 157         .open    = nflog_open,
 158         .read    = seq_read,
 159         .llseek  = seq_lseek,
 160         .release = seq_release,
 161 };
 162
 163 #endif /* PROC_FS */
 164
 165
 166 int __init netfilter_log_init(void)
 167 {
 168 #ifdef CONFIG_PROC_FS
 169         struct proc_dir_entry *pde;
 170
 171         pde = create_proc_entry("nf_log", S_IRUGO, proc_net_netfilter);
 172         if (!pde)
 173                 return -1;
 174
 175         pde->proc_fops = &nflog_file_ops;
 176 #endif
 177         return 0;
 178 }