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 #define NFLOGGER_NAME_LEN               64
  18
  19 static const struct nf_logger *nf_loggers[NFPROTO_NUMPROTO] __read_mostly;
  20 static struct list_head nf_loggers_l[NFPROTO_NUMPROTO] __read_mostly;
  21 static DEFINE_MUTEX(nf_log_mutex);
  22
  23 static struct nf_logger *__find_logger(int pf, const char *str_logger)
  24 {
  25         struct nf_logger *t;
  26
  27         list_for_each_entry(t, &nf_loggers_l[pf], list[pf]) {
  28                 if (!strnicmp(str_logger, t->name, strlen(t->name)))
  29                         return t;
  30         }
  31
  32         return NULL;
  33 }
  34
  35 /* return EEXIST if the same logger is registred, 0 on success. */
  36 int nf_log_register(u_int8_t pf, struct nf_logger *logger)
  37 {
  38         const struct nf_logger *llog;
  39         int i;
  40
  41         if (pf >= ARRAY_SIZE(nf_loggers))
  42                 return -EINVAL;
  43
  44         for (i = 0; i < ARRAY_SIZE(logger->list); i++)
  45                 INIT_LIST_HEAD(&logger->list[i]);
  46
  47         mutex_lock(&nf_log_mutex);
  48
  49         if (pf == NFPROTO_UNSPEC) {
  50                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  51                         list_add_tail(&(logger->list[i]), &(nf_loggers_l[i]));
  52         } else {
  53                 /* register at end of list to honor first register win */
  54                 list_add_tail(&logger->list[pf], &nf_loggers_l[pf]);
  55                 llog = rcu_dereference_protected(nf_loggers[pf],
  56                                                  lockdep_is_held(&nf_log_mutex));
  57                 if (llog == NULL)
  58                         rcu_assign_pointer(nf_loggers[pf], logger);
  59         }
  60
  61         mutex_unlock(&nf_log_mutex);
  62
  63         return 0;
  64 }
  65 EXPORT_SYMBOL(nf_log_register);
  66
  67 void nf_log_unregister(struct nf_logger *logger)
  68 {
  69         const struct nf_logger *c_logger;
  70         int i;
  71
  72         mutex_lock(&nf_log_mutex);
  73         for (i = 0; i < ARRAY_SIZE(nf_loggers); i++) {
  74                 c_logger = rcu_dereference_protected(nf_loggers[i],
  75                                                      lockdep_is_held(&nf_log_mutex));
  76                 if (c_logger == logger)
  77                         rcu_assign_pointer(nf_loggers[i], NULL);
  78                 list_del(&logger->list[i]);
  79         }
  80         mutex_unlock(&nf_log_mutex);
  81
  82         synchronize_rcu();
  83 }
  84 EXPORT_SYMBOL(nf_log_unregister);
  85
  86 int nf_log_bind_pf(u_int8_t pf, const struct nf_logger *logger)
  87 {
  88         mutex_lock(&nf_log_mutex);
  89         if (__find_logger(pf, logger->name) == NULL) {
  90                 mutex_unlock(&nf_log_mutex);
  91                 return -ENOENT;
  92         }
  93         rcu_assign_pointer(nf_loggers[pf], logger);
  94         mutex_unlock(&nf_log_mutex);
  95         return 0;
  96 }
  97 EXPORT_SYMBOL(nf_log_bind_pf);
  98
  99 void nf_log_unbind_pf(u_int8_t pf)
 100 {
 101         mutex_lock(&nf_log_mutex);
 102         rcu_assign_pointer(nf_loggers[pf], NULL);
 103         mutex_unlock(&nf_log_mutex);
 104 }
 105 EXPORT_SYMBOL(nf_log_unbind_pf);
 106
 107 void nf_log_packet(u_int8_t pf,
 108                    unsigned int hooknum,
 109                    const struct sk_buff *skb,
 110                    const struct net_device *in,
 111                    const struct net_device *out,
 112                    const struct nf_loginfo *loginfo,
 113                    const char *fmt, ...)
 114 {
 115         va_list args;
 116         char prefix[NF_LOG_PREFIXLEN];
 117         const struct nf_logger *logger;
 118
 119         rcu_read_lock();
 120         logger = rcu_dereference(nf_loggers[pf]);
 121         if (logger) {
 122                 va_start(args, fmt);
 123                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 124                 va_end(args);
 125                 logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
 126         }
 127         rcu_read_unlock();
 128 }
 129 EXPORT_SYMBOL(nf_log_packet);
 130
 131 #ifdef CONFIG_PROC_FS
 132 static void *seq_start(struct seq_file *seq, loff_t *pos)
 133 {
 134         mutex_lock(&nf_log_mutex);
 135
 136         if (*pos >= ARRAY_SIZE(nf_loggers))
 137                 return NULL;
 138
 139         return pos;
 140 }
 141
 142 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 143 {
 144         (*pos)++;
 145
 146         if (*pos >= ARRAY_SIZE(nf_loggers))
 147                 return NULL;
 148
 149         return pos;
 150 }
 151
 152 static void seq_stop(struct seq_file *s, void *v)
 153 {
 154         mutex_unlock(&nf_log_mutex);
 155 }
 156
 157 static int seq_show(struct seq_file *s, void *v)
 158 {
 159         loff_t *pos = v;
 160         const struct nf_logger *logger;
 161         struct nf_logger *t;
 162         int ret;
 163
 164         logger = nf_loggers[*pos];
 165
 166         if (!logger)
 167                 ret = seq_printf(s, "%2lld NONE (", *pos);
 168         else
 169                 ret = seq_printf(s, "%2lld %s (", *pos, logger->name);
 170
 171         if (ret < 0)
 172                 return ret;
 173
 174         list_for_each_entry(t, &nf_loggers_l[*pos], list[*pos]) {
 175                 ret = seq_printf(s, "%s", t->name);
 176                 if (ret < 0)
 177                         return ret;
 178                 if (&t->list[*pos] != nf_loggers_l[*pos].prev) {
 179                         ret = seq_printf(s, ",");
 180                         if (ret < 0)
 181                                 return ret;
 182                 }
 183         }
 184
 185         return seq_printf(s, ")\n");
 186 }
 187
 188 static const struct seq_operations nflog_seq_ops = {
 189         .start  = seq_start,
 190         .next   = seq_next,
 191         .stop   = seq_stop,
 192         .show   = seq_show,
 193 };
 194
 195 static int nflog_open(struct inode *inode, struct file *file)
 196 {
 197         return seq_open(file, &nflog_seq_ops);
 198 }
 199
 200 static const struct file_operations nflog_file_ops = {
 201         .owner   = THIS_MODULE,
 202         .open    = nflog_open,
 203         .read    = seq_read,
 204         .llseek  = seq_lseek,
 205         .release = seq_release,
 206 };
 207
 208
 209 #endif /* PROC_FS */
 210
 211 #ifdef CONFIG_SYSCTL
 212 static struct ctl_path nf_log_sysctl_path[] = {
 213         { .procname = "net", },
 214         { .procname = "netfilter", },
 215         { .procname = "nf_log", },
 216         { }
 217 };
 218
 219 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 220 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 221 static struct ctl_table_header *nf_log_dir_header;
 222
 223 static int nf_log_proc_dostring(ctl_table *table, int write,
 224                          void __user *buffer, size_t *lenp, loff_t *ppos)
 225 {
 226         const struct nf_logger *logger;
 227         char buf[NFLOGGER_NAME_LEN];
 228         size_t size = *lenp;
 229         int r = 0;
 230         int tindex = (unsigned long)table->extra1;
 231
 232         if (write) {
 233                 if (size > sizeof(buf))
 234                         size = sizeof(buf);
 235                 if (copy_from_user(buf, buffer, size))
 236                         return -EFAULT;
 237
 238                 if (!strcmp(buf, "NONE")) {
 239                         nf_log_unbind_pf(tindex);
 240                         return 0;
 241                 }
 242                 mutex_lock(&nf_log_mutex);
 243                 logger = __find_logger(tindex, buf);
 244                 if (logger == NULL) {
 245                         mutex_unlock(&nf_log_mutex);
 246                         return -ENOENT;
 247                 }
 248                 rcu_assign_pointer(nf_loggers[tindex], logger);
 249                 mutex_unlock(&nf_log_mutex);
 250         } else {
 251                 mutex_lock(&nf_log_mutex);
 252                 logger = nf_loggers[tindex];
 253                 if (!logger)
 254                         table->data = "NONE";
 255                 else
 256                         table->data = logger->name;
 257                 r = proc_dostring(table, write, buffer, lenp, ppos);
 258                 mutex_unlock(&nf_log_mutex);
 259         }
 260
 261         return r;
 262 }
 263
 264 static __init int netfilter_log_sysctl_init(void)
 265 {
 266         int i;
 267
 268         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 269                 snprintf(nf_log_sysctl_fnames[i-NFPROTO_UNSPEC], 3, "%d", i);
 270                 nf_log_sysctl_table[i].procname =
 271                         nf_log_sysctl_fnames[i-NFPROTO_UNSPEC];
 272                 nf_log_sysctl_table[i].data = NULL;
 273                 nf_log_sysctl_table[i].maxlen =
 274                         NFLOGGER_NAME_LEN * sizeof(char);
 275                 nf_log_sysctl_table[i].mode = 0644;
 276                 nf_log_sysctl_table[i].proc_handler = nf_log_proc_dostring;
 277                 nf_log_sysctl_table[i].extra1 = (void *)(unsigned long) i;
 278         }
 279
 280         nf_log_dir_header = register_sysctl_paths(nf_log_sysctl_path,
 281                                        nf_log_sysctl_table);
 282         if (!nf_log_dir_header)
 283                 return -ENOMEM;
 284
 285         return 0;
 286 }
 287 #else
 288 static __init int netfilter_log_sysctl_init(void)
 289 {
 290         return 0;
 291 }
 292 #endif /* CONFIG_SYSCTL */
 293
 294 int __init netfilter_log_init(void)
 295 {
 296         int i, r;
 297 #ifdef CONFIG_PROC_FS
 298         if (!proc_create("nf_log", S_IRUGO,
 299                          proc_net_netfilter, &nflog_file_ops))
 300                 return -1;
 301 #endif
 302
 303         /* Errors will trigger panic, unroll on error is unnecessary. */
 304         r = netfilter_log_sysctl_init();
 305         if (r < 0)
 306                 return r;
 307
 308         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 309                 INIT_LIST_HEAD(&(nf_loggers_l[i]));
 310
 311         return 0;
 312 }