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 #include <net/netfilter/nf_log.h>
  10
  11 #include "nf_internals.h"
  12
  13 /* Internal logging interface, which relies on the real
  14    LOG target modules */
  15
  16 #define NF_LOG_PREFIXLEN                128
  17
  18 static const struct nf_logger *nf_loggers[NPROTO] __read_mostly;
  19 static DEFINE_MUTEX(nf_log_mutex);
  20
  21 /* return EBUSY if somebody else is registered, EEXIST if the same logger
  22  * is registred, 0 on success. */
  23 int nf_log_register(int pf, const struct nf_logger *logger)
  24 {
  25         int ret;
  26
  27         if (pf >= NPROTO)
  28                 return -EINVAL;
  29
  30         /* Any setup of logging members must be done before
  31          * substituting pointer. */
  32         ret = mutex_lock_interruptible(&nf_log_mutex);
  33         if (ret < 0)
  34                 return ret;
  35
  36         if (!nf_loggers[pf])
  37                 rcu_assign_pointer(nf_loggers[pf], logger);
  38         else if (nf_loggers[pf] == logger)
  39                 ret = -EEXIST;
  40         else
  41                 ret = -EBUSY;
  42
  43         mutex_unlock(&nf_log_mutex);
  44         return ret;
  45 }
  46 EXPORT_SYMBOL(nf_log_register);
  47
  48 void nf_log_unregister_pf(int pf)
  49 {
  50         if (pf >= NPROTO)
  51                 return;
  52         mutex_lock(&nf_log_mutex);
  53         rcu_assign_pointer(nf_loggers[pf], NULL);
  54         mutex_unlock(&nf_log_mutex);
  55
  56         /* Give time to concurrent readers. */
  57         synchronize_rcu();
  58 }
  59 EXPORT_SYMBOL(nf_log_unregister_pf);
  60
  61 void nf_log_unregister(const struct nf_logger *logger)
  62 {
  63         int i;
  64
  65         mutex_lock(&nf_log_mutex);
  66         for (i = 0; i < NPROTO; i++) {
  67                 if (nf_loggers[i] == logger)
  68                         rcu_assign_pointer(nf_loggers[i], NULL);
  69         }
  70         mutex_unlock(&nf_log_mutex);
  71
  72         synchronize_rcu();
  73 }
  74 EXPORT_SYMBOL(nf_log_unregister);
  75
  76 void nf_log_packet(int pf,
  77                    unsigned int hooknum,
  78                    const struct sk_buff *skb,
  79                    const struct net_device *in,
  80                    const struct net_device *out,
  81                    const struct nf_loginfo *loginfo,
  82                    const char *fmt, ...)
  83 {
  84         va_list args;
  85         char prefix[NF_LOG_PREFIXLEN];
  86         const struct nf_logger *logger;
  87
  88         rcu_read_lock();
  89         logger = rcu_dereference(nf_loggers[pf]);
  90         if (logger) {
  91                 va_start(args, fmt);
  92                 vsnprintf(prefix, sizeof(prefix), fmt, args);
  93                 va_end(args);
  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         __acquires(RCU)
 107 {
 108         rcu_read_lock();
 109
 110         if (*pos >= NPROTO)
 111                 return NULL;
 112
 113         return pos;
 114 }
 115
 116 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 117 {
 118         (*pos)++;
 119
 120         if (*pos >= NPROTO)
 121                 return NULL;
 122
 123         return pos;
 124 }
 125
 126 static void seq_stop(struct seq_file *s, void *v)
 127         __releases(RCU)
 128 {
 129         rcu_read_unlock();
 130 }
 131
 132 static int seq_show(struct seq_file *s, void *v)
 133 {
 134         loff_t *pos = v;
 135         const struct nf_logger *logger;
 136
 137         logger = rcu_dereference(nf_loggers[*pos]);
 138
 139         if (!logger)
 140                 return seq_printf(s, "%2lld NONE\n", *pos);
 141
 142         return seq_printf(s, "%2lld %s\n", *pos, logger->name);
 143 }
 144
 145 static const struct seq_operations nflog_seq_ops = {
 146         .start  = seq_start,
 147         .next   = seq_next,
 148         .stop   = seq_stop,
 149         .show   = seq_show,
 150 };
 151
 152 static int nflog_open(struct inode *inode, struct file *file)
 153 {
 154         return seq_open(file, &nflog_seq_ops);
 155 }
 156
 157 static const struct file_operations nflog_file_ops = {
 158         .owner   = THIS_MODULE,
 159         .open    = nflog_open,
 160         .read    = seq_read,
 161         .llseek  = seq_lseek,
 162         .release = seq_release,
 163 };
 164
 165 #endif /* PROC_FS */
 166
 167
 168 int __init netfilter_log_init(void)
 169 {
 170 #ifdef CONFIG_PROC_FS
 171         if (!proc_create("nf_log", S_IRUGO,
 172                          proc_net_netfilter, &nflog_file_ops))
 173                 return -1;
 174 #endif
 175         return 0;
 176 }