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