2 * Bouncer -- A Daemon for Turning Away Mischievous Guests
4 * (c) 2016 Martin Mares <mj@ucw.cz>
10 #include <ucw/clists.h>
13 #include <ucw/mainloop.h>
15 #include <ucw/string.h>
18 #include <arpa/inet.h>
21 #include <sys/types.h>
22 #include <sys/socket.h>
28 #include <libipset/data.h>
29 #include <libipset/session.h>
30 #include <libipset/types.h>
32 /*** Internal representation of IPv4/IPv6 addresses ***/
34 // In network byte order, IPv4 represented as ::ffff:1.2.3.4
39 #define ADDR_BUFSIZE 64
40 #define AFMT(_a) ({ char *_buf = alloca(ADDR_BUFSIZE); addr_format(_buf, _a); _buf; })
42 static bool addr_is_v4(struct addr addr)
44 return !addr.a[0] && !addr.a[1] && addr.a[2] == htonl(0xffff);
47 static void addr_format(char *buf, struct addr addr)
53 in4.s_addr = addr.a[3];
54 ok = inet_ntop(AF_INET, &in4, buf, ADDR_BUFSIZE);
59 memcpy(&in6, &addr, sizeof(addr));
60 ok = inet_ntop(AF_INET6, &in6, buf, ADDR_BUFSIZE);
63 snprintf(buf, ADDR_BUFSIZE, "<error %d>", errno);
66 static bool addr_parse(struct addr *addr, const char *src)
71 if (inet_pton(AF_INET, src, &a4))
73 addr->a[0] = addr->a[1] = 0;
74 addr->a[2] = htonl(0xffff);
75 addr->a[3] = a4.s_addr;
78 else if (inet_pton(AF_INET6, src, &a6))
80 memcpy(&addr, &a6, 16);
87 /*** Configuration ***/
89 static char *listen_on = "/var/run/bouncer.sock";
90 static uns max_failures = ~0U;
91 static uns max_suspect_time = 86400;
92 static uns max_banned_time = 86400;
93 static uns max_suspects = ~0U;
94 static uns max_banned = ~0U;
95 static char *ipv4_set;
96 static char *ipv6_set;
97 static char *config_log_stream;
99 static struct cf_section bouncer_cf = {
101 CF_STRING("ListenOn", &listen_on),
102 CF_UNS("MaxSuspects", &max_suspects),
103 CF_UNS("MaxBanned", &max_banned),
104 CF_UNS("MaxSuspectTime", &max_suspect_time),
105 CF_UNS("MaxBannedTime", &max_banned_time),
106 CF_UNS("MaxFailures", &max_failures),
107 CF_STRING("IPv4Set", &ipv4_set),
108 CF_STRING("IPv6Set", &ipv6_set),
109 CF_STRING("LogStream", &config_log_stream),
114 /*** An interface to IP sets ***/
116 static struct ipset_session *is_sess;
118 static const char *trim_eol(const char *msg)
120 int len = strlen(msg);
121 if (!len || msg[len-1] != '\n')
125 char *x = xstrdup(msg);
131 static void is_die(const char *when)
133 const char *warn = ipset_session_warning(is_sess);
135 msg(L_WARN, "%s: %s", when, trim_eol(warn));
137 const char *err = ipset_session_error(is_sess);
138 die("%s: %s", when, err ? trim_eol(err) : "Unknown error");
141 static void is_err(const char *when)
143 const char *warn = ipset_session_warning(is_sess);
145 msg(L_WARN, "%s: %s", when, trim_eol(warn));
147 const char *err = ipset_session_error(is_sess);
148 msg(L_ERROR, "%s: %s", when, err ? trim_eol(err) : "Unknown error");
150 ipset_session_report_reset(is_sess);
153 static void is_init(void)
157 is_sess = ipset_session_init(printf);
159 die("Unable to initialize ipset session");
162 static bool is_setup(char *set)
167 if (ipset_parse_setname(is_sess, IPSET_SETNAME, set) < 0)
168 is_die("ipset_parse_setname");
172 static void is_flush(char *set)
177 if (ipset_cmd(is_sess, IPSET_CMD_FLUSH, 0) < 0)
178 return is_err("IPSET_CMD_FLUSH");
181 static bool is_modify(bool add, struct addr addr)
183 int cmd = add ? IPSET_CMD_ADD : IPSET_CMD_DEL;
184 char *set = addr_is_v4(addr) ? ipv4_set : ipv6_set;
188 if (ipset_envopt_parse(is_sess, IPSET_ENV_EXIST, NULL) < 0)
189 is_die("IPSET_ENV_EXIST");
191 const struct ipset_type *is_type = ipset_type_get(is_sess, cmd);
193 is_die("ipset_type_get");
195 if (is_type->dimension != 1)
196 die("Invalid ipset dimension %d", is_type->dimension);
198 char buf[ADDR_BUFSIZE];
199 addr_format(buf, addr);
200 if (ipset_parse_elem(is_sess, 0, buf) < 0)
202 is_err("ipset_parse_elem");
206 if (ipset_cmd(is_sess, cmd, 0) < 0)
208 is_err(add ? "IPSET_CMD_ADD" : "IPSET_CMD_DEL");
215 /*** Handling of login failures ***/
217 struct culprit_node {
218 cnode n; // In either suspect_list or banned_list
225 timestamp_t last_fail; // Not updated when banned
228 #define HASH_NODE struct culprit_node
229 #define HASH_PREFIX(x) culprit_##x
230 #define HASH_KEY_MEMORY addr_bytes
231 #define HASH_KEY_SIZE 16
232 #define HASH_WANT_LOOKUP
233 #define HASH_WANT_REMOVE
234 #define HASH_USE_AUTO_ELTPOOL 1000
235 #define HASH_ZERO_FILL
236 #define HASH_LOOKUP_DETECT_NEW
237 #include <ucw/hashtable.h>
239 static clist suspect_list, banned_list;
240 static uns num_suspects, num_banned;
241 static struct main_timer cleanup_timer;
243 static void cleanup_list(clist *list, uns *counter, timestamp_t max_time, uns max_count, timestamp_t *next)
245 timestamp_t now = main_get_now();
249 struct culprit_node *c = clist_head(list);
253 timestamp_t expire_in = c->last_fail + max_time;
254 if (*counter > max_count)
256 static timestamp_t last_overflow_warning;
257 if (last_overflow_warning + 60000 < now)
259 last_overflow_warning = now;
261 msg(L_WARN, "Too many bans, dropping some. Try increasing MaxBanned.");
263 msg(L_WARN, "Too many suspects, dropping some. Try increasing MaxSuspects.");
270 *next = MIN(*next, expire_in);
276 msg(L_INFO, "Unbanning %s", AFMT(c->addr));
277 is_modify(0, c->addr);
280 msg(L_DEBUG, "Suspect %s: acquitted", AFMT(c->addr));
288 static void culprit_cleanup(void)
290 timestamp_t next_cleanup = main_get_now() + (timestamp_t)3600 * 1000;
291 cleanup_list(&suspect_list, &num_suspects, (timestamp_t)max_suspect_time * 1000, max_suspects, &next_cleanup);
292 cleanup_list(&banned_list, &num_banned, (timestamp_t)max_banned_time * 1000, max_banned, &next_cleanup);
293 timer_add(&cleanup_timer, next_cleanup);
296 static void handle_failed_login(struct addr addr, int cnt)
299 timestamp_t now = main_get_now();
301 struct culprit_node *c = culprit_lookup((byte *) &addr, &is_new);
307 clist_add_tail(&suspect_list, &c->n);
309 msg(L_DEBUG, "Suspect %s: new, failures=%u", AFMT(addr), c->fail_count);
314 c->fail_count += cnt;
316 clist_add_tail(&suspect_list, &c->n);
317 msg(L_DEBUG, "Suspect %s: failures=%u", AFMT(addr), c->fail_count);
320 if (!c->banned && c->fail_count >= max_failures)
322 msg(L_INFO, "Banning %s: failures=%u", AFMT(addr), c->fail_count);
326 clist_add_tail(&banned_list, &c->n);
328 is_modify(1, c->addr);
334 static void culprit_timer(struct main_timer *tm UNUSED)
339 static void fail_init(void)
342 clist_init(&suspect_list);
343 clist_init(&banned_list);
344 cleanup_timer.handler = culprit_timer;
347 /*** Parsing of log messages ***/
349 static bool check_next(char **pp, char *want)
361 static void parse_failure(char *p, int cnt)
363 DBG("Parse 4: <%s> cnt=%d", p, cnt);
376 while (*p && *p != ' ' && *p != '=')
383 while (*p && *p != ' ')
390 DBG("Parse KV: %s=<%s>", key, val);
391 if (!strcmp(key, "rhost"))
395 // Act on the message
397 if (addr_parse(&addr, rhost))
398 handle_failed_login(addr, cnt);
400 msg(L_WARN, "Unable to parse address %s", rhost);
403 static void process_msg(char *line)
405 DBG("Parse: <%s>", line);
409 // 2016-11-04T17:18:54.825821+01:00 sshd[6733]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=1.2.3.4
410 // 2016-11-05T12:49:52.418880+01:00 sshd[16271]: PAM 2 more authentication failures; logname= uid=0 euid=0 tty=ssh ruser= rhost=116.31.116.26 user=root
412 // We shall start with 32 non-spaces
413 for (int i=0; i<32; i++)
419 DBG("Parse 1: <%s>", p);
421 // Space, something, colon, space
424 while (*p && *p != ' ' && *p != ':')
426 if (!check_next(&p, ": "))
428 DBG("Parse 2: <%s>", p);
430 // pam_unix(something), colon, space
431 if (check_next(&p, "pam_unix("))
440 if (!check_next(&p, ": "))
442 DBG("Parse 3: <%s>", p);
444 if (!check_next(&p, "authentication failure; "))
450 // "PAM <n> more authentication failures;"
451 if (check_next(&p, "PAM "))
453 if (!(*p >= '0' && *p <= '9'))
456 while (*p >= '0' && *p <= '9')
459 if (!check_next(&p, " more authentication failures; "))
462 parse_failure(p, cnt);
466 /*** Socket for receiving messages from rsyslog ***/
468 struct main_file sk_file;
470 static int sk_read(struct main_file *mf)
473 int len = recv(mf->fd, line, sizeof(line), MSG_TRUNC);
476 if (errno == EINTR || errno == EAGAIN)
481 if (len >= (int) sizeof(line))
483 msg(L_WARN, "Truncated message received (length=%d)", len);
484 len = sizeof(line) - 1;
488 if (len > 0 && line[len-1] == '\n')
490 if (len > 0 && line[len-1] == '\r')
497 static void sk_init(void)
500 mode_t old_umask = umask(0077);
503 if ((fd = socket(PF_UNIX, SOCK_DGRAM, 0)) < 0)
504 die("Cannot create PF_UNIX socket: %m");
506 struct sockaddr_un sa = { .sun_family = AF_UNIX };
507 strcpy(sa.sun_path, listen_on);
508 if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
509 die("Cannot bind socket %s: %m", listen_on);
512 sk_file.read_handler = sk_read;
520 static struct opt_section options = {
522 OPT_HELP("Bouncer -- A Daemon for Turning Away Mischievous Guests"),
524 OPT_HELP("Options:"),
531 int main(int argc UNUSED, char **argv)
533 cf_def_file = "config"; // FIXME
534 cf_declare_section("Bouncer", &bouncer_cf, 0);
535 opt_parse(&options, argv+1);
537 if (config_log_stream)
538 log_configured(config_log_stream);
548 msg(L_INFO, "Starting");