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                 int i;
  51                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  52                         list_add_tail(&(logger->list[i]), &(nf_loggers_l[i]));
  53         } else {
  54                 /* register at end of list to honor first register win */
  55                 list_add_tail(&logger->list[pf], &nf_loggers_l[pf]);
  56                 llog = rcu_dereference(nf_loggers[pf]);
  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(nf_loggers[i]);
  75                 if (c_logger == logger)
  76                         rcu_assign_pointer(nf_loggers[i], NULL);
  77                 list_del(&logger->list[i]);
  78         }
  79         mutex_unlock(&nf_log_mutex);
  80
  81         synchronize_rcu();
  82 }
  83 EXPORT_SYMBOL(nf_log_unregister);
  84
  85 int nf_log_bind_pf(u_int8_t pf, const struct nf_logger *logger)
  86 {
  87         mutex_lock(&nf_log_mutex);
  88         if (__find_logger(pf, logger->name) == NULL) {
  89                 mutex_unlock(&nf_log_mutex);
  90                 return -ENOENT;
  91         }
  92         rcu_assign_pointer(nf_loggers[pf], logger);
  93         mutex_unlock(&nf_log_mutex);
  94         return 0;
  95 }
  96 EXPORT_SYMBOL(nf_log_bind_pf);
  97
  98 void nf_log_unbind_pf(u_int8_t pf)
  99 {
 100         mutex_lock(&nf_log_mutex);
 101         rcu_assign_pointer(nf_loggers[pf], NULL);
 102         mutex_unlock(&nf_log_mutex);
 103 }
 104 EXPORT_SYMBOL(nf_log_unbind_pf);
 105
 106 void nf_log_packet(u_int8_t pf,
 107                    unsigned int hooknum,
 108                    const struct sk_buff *skb,
 109                    const struct net_device *in,
 110                    const struct net_device *out,
 111                    const struct nf_loginfo *loginfo,
 112                    const char *fmt, ...)
 113 {
 114         va_list args;
 115         char prefix[NF_LOG_PREFIXLEN];
 116         const struct nf_logger *logger;
 117
 118         rcu_read_lock();
 119         logger = rcu_dereference(nf_loggers[pf]);
 120         if (logger) {
 121                 va_start(args, fmt);
 122                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 123                 va_end(args);
 124                 logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
 125         }
 126         rcu_read_unlock();
 127 }
 128 EXPORT_SYMBOL(nf_log_packet);
 129
 130 #ifdef CONFIG_PROC_FS
 131 static void *seq_start(struct seq_file *seq, loff_t *pos)
 132         __acquires(RCU)
 133 {
 134         rcu_read_lock();
 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         __releases(RCU)
 154 {
 155         rcu_read_unlock();
 156 }
 157
 158 static int seq_show(struct seq_file *s, void *v)
 159 {
 160         loff_t *pos = v;
 161         const struct nf_logger *logger;
 162         struct nf_logger *t;
 163         int ret;
 164
 165         logger = rcu_dereference(nf_loggers[*pos]);
 166
 167         if (!logger)
 168                 ret = seq_printf(s, "%2lld NONE (", *pos);
 169         else
 170                 ret = seq_printf(s, "%2lld %s (", *pos, logger->name);
 171
 172         if (ret < 0)
 173                 return ret;
 174
 175         mutex_lock(&nf_log_mutex);
 176         list_for_each_entry(t, &nf_loggers_l[*pos], list[*pos]) {
 177                 ret = seq_printf(s, "%s", t->name);
 178                 if (ret < 0) {
 179                         mutex_unlock(&nf_log_mutex);
 180                         return ret;
 181                 }
 182                 if (&t->list[*pos] != nf_loggers_l[*pos].prev) {
 183                         ret = seq_printf(s, ",");
 184                         if (ret < 0) {
 185                                 mutex_unlock(&nf_log_mutex);
 186                                 return ret;
 187                         }
 188                 }
 189         }
 190         mutex_unlock(&nf_log_mutex);
 191
 192         return seq_printf(s, ")\n");
 193 }
 194
 195 static const struct seq_operations nflog_seq_ops = {
 196         .start  = seq_start,
 197         .next   = seq_next,
 198         .stop   = seq_stop,
 199         .show   = seq_show,
 200 };
 201
 202 static int nflog_open(struct inode *inode, struct file *file)
 203 {
 204         return seq_open(file, &nflog_seq_ops);
 205 }
 206
 207 static const struct file_operations nflog_file_ops = {
 208         .owner   = THIS_MODULE,
 209         .open    = nflog_open,
 210         .read    = seq_read,
 211         .llseek  = seq_lseek,
 212         .release = seq_release,
 213 };
 214
 215
 216 #endif /* PROC_FS */
 217
 218 #ifdef CONFIG_SYSCTL
 219 struct ctl_path nf_log_sysctl_path[] = {
 220         { .procname = "net", .ctl_name = CTL_NET, },
 221         { .procname = "netfilter", .ctl_name = NET_NETFILTER, },
 222         { .procname = "nf_log", .ctl_name = CTL_UNNUMBERED, },
 223         { }
 224 };
 225
 226 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 227 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 228 static struct ctl_table_header *nf_log_dir_header;
 229
 230 static int nf_log_proc_dostring(ctl_table *table, int write, struct file *filp,
 231                          void *buffer, size_t *lenp, loff_t *ppos)
 232 {
 233         const struct nf_logger *logger;
 234         int r = 0;
 235         int tindex = (unsigned long)table->extra1;
 236
 237         if (write) {
 238                 if (!strcmp(buffer, "NONE")) {
 239                         nf_log_unbind_pf(tindex);
 240                         return 0;
 241                 }
 242                 mutex_lock(&nf_log_mutex);
 243                 logger = __find_logger(tindex, buffer);
 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                 rcu_read_lock();
 252                 logger = rcu_dereference(nf_loggers[tindex]);
 253                 if (!logger)
 254                         table->data = "NONE";
 255                 else
 256                         table->data = logger->name;
 257                 r = proc_dostring(table, write, filp, buffer, lenp, ppos);
 258                 rcu_read_unlock();
 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].ctl_name = CTL_UNNUMBERED;
 271                 nf_log_sysctl_table[i].procname =
 272                         nf_log_sysctl_fnames[i-NFPROTO_UNSPEC];
 273                 nf_log_sysctl_table[i].data = NULL;
 274                 nf_log_sysctl_table[i].maxlen =
 275                         NFLOGGER_NAME_LEN * sizeof(char);
 276                 nf_log_sysctl_table[i].mode = 0644;
 277                 nf_log_sysctl_table[i].proc_handler = nf_log_proc_dostring;
 278                 nf_log_sysctl_table[i].extra1 = (void *)(unsigned long) i;
 279         }
 280
 281         nf_log_dir_header = register_sysctl_paths(nf_log_sysctl_path,
 282                                        nf_log_sysctl_table);
 283         if (!nf_log_dir_header)
 284                 return -ENOMEM;
 285
 286         return 0;
 287 }
 288 #else
 289 static __init int netfilter_log_sysctl_init(void)
 290 {
 291         return 0;
 292 }
 293 #endif /* CONFIG_SYSCTL */
 294
 295 int __init netfilter_log_init(void)
 296 {
 297         int i, r;
 298 #ifdef CONFIG_PROC_FS
 299         if (!proc_create("nf_log", S_IRUGO,
 300                          proc_net_netfilter, &nflog_file_ops))
 301                 return -1;
 302 #endif
 303
 304         /* Errors will trigger panic, unroll on error is unnecessary. */
 305         r = netfilter_log_sysctl_init();
 306         if (r < 0)
 307                 return r;
 308
 309         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 310                 INIT_LIST_HEAD(&(nf_loggers_l[i]));
 311
 312         return 0;
 313 }