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 __rcu *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_INIT_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_INIT_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         if (pf >= ARRAY_SIZE(nf_loggers))
  89                 return -EINVAL;
  90         mutex_lock(&nf_log_mutex);
  91         if (__find_logger(pf, logger->name) == NULL) {
  92                 mutex_unlock(&nf_log_mutex);
  93                 return -ENOENT;
  94         }
  95         RCU_INIT_POINTER(nf_loggers[pf], logger);
  96         mutex_unlock(&nf_log_mutex);
  97         return 0;
  98 }
  99 EXPORT_SYMBOL(nf_log_bind_pf);
 100
 101 void nf_log_unbind_pf(u_int8_t pf)
 102 {
 103         if (pf >= ARRAY_SIZE(nf_loggers))
 104                 return;
 105         mutex_lock(&nf_log_mutex);
 106         RCU_INIT_POINTER(nf_loggers[pf], NULL);
 107         mutex_unlock(&nf_log_mutex);
 108 }
 109 EXPORT_SYMBOL(nf_log_unbind_pf);
 110
 111 void nf_log_packet(u_int8_t pf,
 112                    unsigned int hooknum,
 113                    const struct sk_buff *skb,
 114                    const struct net_device *in,
 115                    const struct net_device *out,
 116                    const struct nf_loginfo *loginfo,
 117                    const char *fmt, ...)
 118 {
 119         va_list args;
 120         char prefix[NF_LOG_PREFIXLEN];
 121         const struct nf_logger *logger;
 122
 123         rcu_read_lock();
 124         logger = rcu_dereference(nf_loggers[pf]);
 125         if (logger) {
 126                 va_start(args, fmt);
 127                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 128                 va_end(args);
 129                 logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
 130         }
 131         rcu_read_unlock();
 132 }
 133 EXPORT_SYMBOL(nf_log_packet);
 134
 135 #ifdef CONFIG_PROC_FS
 136 static void *seq_start(struct seq_file *seq, loff_t *pos)
 137 {
 138         mutex_lock(&nf_log_mutex);
 139
 140         if (*pos >= ARRAY_SIZE(nf_loggers))
 141                 return NULL;
 142
 143         return pos;
 144 }
 145
 146 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 147 {
 148         (*pos)++;
 149
 150         if (*pos >= ARRAY_SIZE(nf_loggers))
 151                 return NULL;
 152
 153         return pos;
 154 }
 155
 156 static void seq_stop(struct seq_file *s, void *v)
 157 {
 158         mutex_unlock(&nf_log_mutex);
 159 }
 160
 161 static int seq_show(struct seq_file *s, void *v)
 162 {
 163         loff_t *pos = v;
 164         const struct nf_logger *logger;
 165         struct nf_logger *t;
 166         int ret;
 167
 168         logger = rcu_dereference_protected(nf_loggers[*pos],
 169                                            lockdep_is_held(&nf_log_mutex));
 170
 171         if (!logger)
 172                 ret = seq_printf(s, "%2lld NONE (", *pos);
 173         else
 174                 ret = seq_printf(s, "%2lld %s (", *pos, logger->name);
 175
 176         if (ret < 0)
 177                 return ret;
 178
 179         list_for_each_entry(t, &nf_loggers_l[*pos], list[*pos]) {
 180                 ret = seq_printf(s, "%s", t->name);
 181                 if (ret < 0)
 182                         return ret;
 183                 if (&t->list[*pos] != nf_loggers_l[*pos].prev) {
 184                         ret = seq_printf(s, ",");
 185                         if (ret < 0)
 186                                 return ret;
 187                 }
 188         }
 189
 190         return seq_printf(s, ")\n");
 191 }
 192
 193 static const struct seq_operations nflog_seq_ops = {
 194         .start  = seq_start,
 195         .next   = seq_next,
 196         .stop   = seq_stop,
 197         .show   = seq_show,
 198 };
 199
 200 static int nflog_open(struct inode *inode, struct file *file)
 201 {
 202         return seq_open(file, &nflog_seq_ops);
 203 }
 204
 205 static const struct file_operations nflog_file_ops = {
 206         .owner   = THIS_MODULE,
 207         .open    = nflog_open,
 208         .read    = seq_read,
 209         .llseek  = seq_lseek,
 210         .release = seq_release,
 211 };
 212
 213
 214 #endif /* PROC_FS */
 215
 216 #ifdef CONFIG_SYSCTL
 217 static struct ctl_path nf_log_sysctl_path[] = {
 218         { .procname = "net", },
 219         { .procname = "netfilter", },
 220         { .procname = "nf_log", },
 221         { }
 222 };
 223
 224 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 225 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 226 static struct ctl_table_header *nf_log_dir_header;
 227
 228 static int nf_log_proc_dostring(ctl_table *table, int write,
 229                          void __user *buffer, size_t *lenp, loff_t *ppos)
 230 {
 231         const struct nf_logger *logger;
 232         char buf[NFLOGGER_NAME_LEN];
 233         size_t size = *lenp;
 234         int r = 0;
 235         int tindex = (unsigned long)table->extra1;
 236
 237         if (write) {
 238                 if (size > sizeof(buf))
 239                         size = sizeof(buf);
 240                 if (copy_from_user(buf, buffer, size))
 241                         return -EFAULT;
 242
 243                 if (!strcmp(buf, "NONE")) {
 244                         nf_log_unbind_pf(tindex);
 245                         return 0;
 246                 }
 247                 mutex_lock(&nf_log_mutex);
 248                 logger = __find_logger(tindex, buf);
 249                 if (logger == NULL) {
 250                         mutex_unlock(&nf_log_mutex);
 251                         return -ENOENT;
 252                 }
 253                 RCU_INIT_POINTER(nf_loggers[tindex], logger);
 254                 mutex_unlock(&nf_log_mutex);
 255         } else {
 256                 mutex_lock(&nf_log_mutex);
 257                 logger = rcu_dereference_protected(nf_loggers[tindex],
 258                                                    lockdep_is_held(&nf_log_mutex));
 259                 if (!logger)
 260                         table->data = "NONE";
 261                 else
 262                         table->data = logger->name;
 263                 r = proc_dostring(table, write, buffer, lenp, ppos);
 264                 mutex_unlock(&nf_log_mutex);
 265         }
 266
 267         return r;
 268 }
 269
 270 static __init int netfilter_log_sysctl_init(void)
 271 {
 272         int i;
 273
 274         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
 275                 snprintf(nf_log_sysctl_fnames[i-NFPROTO_UNSPEC], 3, "%d", i);
 276                 nf_log_sysctl_table[i].procname =
 277                         nf_log_sysctl_fnames[i-NFPROTO_UNSPEC];
 278                 nf_log_sysctl_table[i].data = NULL;
 279                 nf_log_sysctl_table[i].maxlen =
 280                         NFLOGGER_NAME_LEN * sizeof(char);
 281                 nf_log_sysctl_table[i].mode = 0644;
 282                 nf_log_sysctl_table[i].proc_handler = nf_log_proc_dostring;
 283                 nf_log_sysctl_table[i].extra1 = (void *)(unsigned long) i;
 284         }
 285
 286         nf_log_dir_header = register_sysctl_paths(nf_log_sysctl_path,
 287                                        nf_log_sysctl_table);
 288         if (!nf_log_dir_header)
 289                 return -ENOMEM;
 290
 291         return 0;
 292 }
 293 #else
 294 static __init int netfilter_log_sysctl_init(void)
 295 {
 296         return 0;
 297 }
 298 #endif /* CONFIG_SYSCTL */
 299
 300 int __init netfilter_log_init(void)
 301 {
 302         int i, r;
 303 #ifdef CONFIG_PROC_FS
 304         if (!proc_create("nf_log", S_IRUGO,
 305                          proc_net_netfilter, &nflog_file_ops))
 306                 return -1;
 307 #endif
 308
 309         /* Errors will trigger panic, unroll on error is unnecessary. */
 310         r = netfilter_log_sysctl_init();
 311         if (r < 0)
 312                 return r;
 313
 314         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 315                 INIT_LIST_HEAD(&(nf_loggers_l[i]));
 316
 317         return 0;
 318 }