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