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(nf_loggers[pf]);
  56                 if (llog == NULL)
  57                         rcu_assign_pointer(nf_loggers[pf], logger);
  58         }
  59
  60         mutex_unlock(&nf_log_mutex);
  61
  62         return 0;
  63 }
  64 EXPORT_SYMBOL(nf_log_register);
  65
  66 void nf_log_unregister(struct nf_logger *logger)
  67 {
  68         const struct nf_logger *c_logger;
  69         int i;
  70
  71         mutex_lock(&nf_log_mutex);
  72         for (i = 0; i < ARRAY_SIZE(nf_loggers); i++) {
  73                 c_logger = rcu_dereference(nf_loggers[i]);
  74                 if (c_logger == logger)
  75                         rcu_assign_pointer(nf_loggers[i], NULL);
  76                 list_del(&logger->list[i]);
  77         }
  78         mutex_unlock(&nf_log_mutex);
  79
  80         synchronize_rcu();
  81 }
  82 EXPORT_SYMBOL(nf_log_unregister);
  83
  84 int nf_log_bind_pf(u_int8_t pf, const struct nf_logger *logger)
  85 {
  86         mutex_lock(&nf_log_mutex);
  87         if (__find_logger(pf, logger->name) == NULL) {
  88                 mutex_unlock(&nf_log_mutex);
  89                 return -ENOENT;
  90         }
  91         rcu_assign_pointer(nf_loggers[pf], logger);
  92         mutex_unlock(&nf_log_mutex);
  93         return 0;
  94 }
  95 EXPORT_SYMBOL(nf_log_bind_pf);
  96
  97 void nf_log_unbind_pf(u_int8_t pf)
  98 {
  99         mutex_lock(&nf_log_mutex);
 100         rcu_assign_pointer(nf_loggers[pf], NULL);
 101         mutex_unlock(&nf_log_mutex);
 102 }
 103 EXPORT_SYMBOL(nf_log_unbind_pf);
 104
 105 void nf_log_packet(u_int8_t pf,
 106                    unsigned int hooknum,
 107                    const struct sk_buff *skb,
 108                    const struct net_device *in,
 109                    const struct net_device *out,
 110                    const struct nf_loginfo *loginfo,
 111                    const char *fmt, ...)
 112 {
 113         va_list args;
 114         char prefix[NF_LOG_PREFIXLEN];
 115         const struct nf_logger *logger;
 116
 117         rcu_read_lock();
 118         logger = rcu_dereference(nf_loggers[pf]);
 119         if (logger) {
 120                 va_start(args, fmt);
 121                 vsnprintf(prefix, sizeof(prefix), fmt, args);
 122                 va_end(args);
 123                 logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
 124         }
 125         rcu_read_unlock();
 126 }
 127 EXPORT_SYMBOL(nf_log_packet);
 128
 129 #ifdef CONFIG_PROC_FS
 130 static void *seq_start(struct seq_file *seq, loff_t *pos)
 131         __acquires(RCU)
 132 {
 133         rcu_read_lock();
 134
 135         if (*pos >= ARRAY_SIZE(nf_loggers))
 136                 return NULL;
 137
 138         return pos;
 139 }
 140
 141 static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
 142 {
 143         (*pos)++;
 144
 145         if (*pos >= ARRAY_SIZE(nf_loggers))
 146                 return NULL;
 147
 148         return pos;
 149 }
 150
 151 static void seq_stop(struct seq_file *s, void *v)
 152         __releases(RCU)
 153 {
 154         rcu_read_unlock();
 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 = rcu_dereference(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         mutex_lock(&nf_log_mutex);
 175         list_for_each_entry(t, &nf_loggers_l[*pos], list[*pos]) {
 176                 ret = seq_printf(s, "%s", t->name);
 177                 if (ret < 0) {
 178                         mutex_unlock(&nf_log_mutex);
 179                         return ret;
 180                 }
 181                 if (&t->list[*pos] != nf_loggers_l[*pos].prev) {
 182                         ret = seq_printf(s, ",");
 183                         if (ret < 0) {
 184                                 mutex_unlock(&nf_log_mutex);
 185                                 return ret;
 186                         }
 187                 }
 188         }
 189         mutex_unlock(&nf_log_mutex);
 190
 191         return seq_printf(s, ")\n");
 192 }
 193
 194 static const struct seq_operations nflog_seq_ops = {
 195         .start  = seq_start,
 196         .next   = seq_next,
 197         .stop   = seq_stop,
 198         .show   = seq_show,
 199 };
 200
 201 static int nflog_open(struct inode *inode, struct file *file)
 202 {
 203         return seq_open(file, &nflog_seq_ops);
 204 }
 205
 206 static const struct file_operations nflog_file_ops = {
 207         .owner   = THIS_MODULE,
 208         .open    = nflog_open,
 209         .read    = seq_read,
 210         .llseek  = seq_lseek,
 211         .release = seq_release,
 212 };
 213
 214
 215 #endif /* PROC_FS */
 216
 217 #ifdef CONFIG_SYSCTL
 218 static struct ctl_path nf_log_sysctl_path[] = {
 219         { .procname = "net", .ctl_name = CTL_NET, },
 220         { .procname = "netfilter", .ctl_name = NET_NETFILTER, },
 221         { .procname = "nf_log", .ctl_name = CTL_UNNUMBERED, },
 222         { }
 223 };
 224
 225 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
 226 static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 227 static struct ctl_table_header *nf_log_dir_header;
 228
 229 static int nf_log_proc_dostring(ctl_table *table, int write,
 230                          void __user *buffer, size_t *lenp, loff_t *ppos)
 231 {
 232         const struct nf_logger *logger;
 233         char buf[NFLOGGER_NAME_LEN];
 234         size_t size = *lenp;
 235         int r = 0;
 236         int tindex = (unsigned long)table->extra1;
 237
 238         if (write) {
 239                 if (size > sizeof(buf))
 240                         size = sizeof(buf);
 241                 if (copy_from_user(buf, buffer, size))
 242                         return -EFAULT;
 243
 244                 if (!strcmp(buf, "NONE")) {
 245                         nf_log_unbind_pf(tindex);
 246                         return 0;
 247                 }
 248                 mutex_lock(&nf_log_mutex);
 249                 logger = __find_logger(tindex, buf);
 250                 if (logger == NULL) {
 251                         mutex_unlock(&nf_log_mutex);
 252                         return -ENOENT;
 253                 }
 254                 rcu_assign_pointer(nf_loggers[tindex], logger);
 255                 mutex_unlock(&nf_log_mutex);
 256         } else {
 257                 mutex_lock(&nf_log_mutex);
 258                 logger = nf_loggers[tindex];
 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].ctl_name = CTL_UNNUMBERED;
 277                 nf_log_sysctl_table[i].procname =
 278                         nf_log_sysctl_fnames[i-NFPROTO_UNSPEC];
 279                 nf_log_sysctl_table[i].data = NULL;
 280                 nf_log_sysctl_table[i].maxlen =
 281                         NFLOGGER_NAME_LEN * sizeof(char);
 282                 nf_log_sysctl_table[i].mode = 0644;
 283                 nf_log_sysctl_table[i].proc_handler = nf_log_proc_dostring;
 284                 nf_log_sysctl_table[i].extra1 = (void *)(unsigned long) i;
 285         }
 286
 287         nf_log_dir_header = register_sysctl_paths(nf_log_sysctl_path,
 288                                        nf_log_sysctl_table);
 289         if (!nf_log_dir_header)
 290                 return -ENOMEM;
 291
 292         return 0;
 293 }
 294 #else
 295 static __init int netfilter_log_sysctl_init(void)
 296 {
 297         return 0;
 298 }
 299 #endif /* CONFIG_SYSCTL */
 300
 301 int __init netfilter_log_init(void)
 302 {
 303         int i, r;
 304 #ifdef CONFIG_PROC_FS
 305         if (!proc_create("nf_log", S_IRUGO,
 306                          proc_net_netfilter, &nflog_file_ops))
 307                 return -1;
 308 #endif
 309
 310         /* Errors will trigger panic, unroll on error is unnecessary. */
 311         r = netfilter_log_sysctl_init();
 312         if (r < 0)
 313                 return r;
 314
 315         for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
 316                 INIT_LIST_HEAD(&(nf_loggers_l[i]));
 317
 318         return 0;
 319 }