diff options
Diffstat (limited to 'src/ctnl.c')
| -rw-r--r-- | src/ctnl.c | 524 |
1 files changed, 524 insertions, 0 deletions
diff --git a/src/ctnl.c b/src/ctnl.c new file mode 100644 index 0000000..10b5f4c --- /dev/null +++ b/src/ctnl.c @@ -0,0 +1,524 @@ +/* + * (C) 2006-2012 by Pablo Neira Ayuso <pablo@netfilter.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + * Part of this code has been sponsored by Vyatta Inc. <http://www.vyatta.com> + */ + +#include "conntrackd.h" +#include "netlink.h" +#include "filter.h" +#include "log.h" +#include "alarm.h" +#include "fds.h" +#include "traffic_stats.h" +#include "process.h" +#include "origin.h" +#include "date.h" +#include "internal.h" + +#include <errno.h> +#include <signal.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/wait.h> +#include <string.h> +#include <time.h> +#include <fcntl.h> + +void ctnl_kill(void) +{ + if (!(CONFIG(flags) & CTD_POLL)) + nfct_close(STATE(event)); + + nfct_close(STATE(resync)); + nfct_close(STATE(get)); + origin_unregister(STATE(flush)); + nfct_close(STATE(flush)); + + if (STATE(us_filter)) + ct_filter_destroy(STATE(us_filter)); + STATE(mode)->kill(); + + if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) { + nfct_close(STATE(dump)); + } +} + +static void local_flush_master(void) +{ + STATE(stats).nl_kernel_table_flush++; + dlog(LOG_NOTICE, "flushing kernel conntrack table"); + + /* fork a child process that performs the flush operation, + * meanwhile the parent process handles events. */ + if (fork_process_new(CTD_PROC_FLUSH, CTD_PROC_F_EXCL, + NULL, NULL) == 0) { + nl_flush_conntrack_table_selective(); + exit(EXIT_SUCCESS); + } +} + +static void local_resync_master(void) +{ + if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) { + STATE(stats).nl_kernel_table_resync++; + dlog(LOG_NOTICE, "resync with master conntrack table"); + nl_dump_conntrack_table(STATE(dump)); + } else { + dlog(LOG_NOTICE, "resync is unsupported in this mode"); + } +} + +static void local_exp_flush_master(void) +{ + if (!(CONFIG(flags) & CTD_EXPECT)) + return; + + STATE(stats).nl_kernel_table_flush++; + dlog(LOG_NOTICE, "flushing kernel expect table"); + + /* fork a child process that performs the flush operation, + * meanwhile the parent process handles events. */ + if (fork_process_new(CTD_PROC_FLUSH, CTD_PROC_F_EXCL, + NULL, NULL) == 0) { + nl_flush_expect_table(STATE(flush)); + exit(EXIT_SUCCESS); + } +} + +static void local_exp_resync_master(void) +{ + if (!(CONFIG(flags) & CTD_EXPECT)) + return; + + if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) { + STATE(stats).nl_kernel_table_resync++; + dlog(LOG_NOTICE, "resync with master expect table"); + nl_dump_expect_table(STATE(dump)); + } else { + dlog(LOG_NOTICE, "resync is unsupported in this mode"); + } +} + +int ctnl_local(int fd, int type, void *data) +{ + int ret = LOCAL_RET_OK; + + switch(type) { + case CT_FLUSH_MASTER: + local_flush_master(); + break; + case CT_RESYNC_MASTER: + local_resync_master(); + break; + case EXP_FLUSH_MASTER: + local_exp_flush_master(); + break; + case EXP_RESYNC_MASTER: + local_exp_resync_master(); + break; + case ALL_FLUSH_MASTER: + local_flush_master(); + local_exp_flush_master(); + break; + case ALL_RESYNC_MASTER: + local_resync_master(); + local_exp_resync_master(); + break; + } + + ret = STATE(mode)->local(fd, type, data); + if (ret == LOCAL_RET_ERROR) { + STATE(stats).local_unknown_request++; + return LOCAL_RET_ERROR; + } + return ret; +} + +static void do_overrun_resync_alarm(struct alarm_block *a, void *data) +{ + nl_send_resync(STATE(resync)); + STATE(stats).nl_kernel_table_resync++; +} + +static void do_polling_alarm(struct alarm_block *a, void *data) +{ + if (STATE(mode)->internal->ct.purge) + STATE(mode)->internal->ct.purge(); + + if (STATE(mode)->internal->exp.purge) + STATE(mode)->internal->exp.purge(); + + nl_send_resync(STATE(resync)); + if (CONFIG(flags) & CTD_EXPECT) + nl_send_expect_resync(STATE(resync)); + + add_alarm(&STATE(polling_alarm), CONFIG(poll_kernel_secs), 0); +} + +static int event_handler(const struct nlmsghdr *nlh, + enum nf_conntrack_msg_type type, + struct nf_conntrack *ct, + void *data) +{ + int origin_type; + + STATE(stats).nl_events_received++; + + /* skip user-space filtering if already do it in the kernel */ + if (ct_filter_conntrack(ct, !CONFIG(filter_from_kernelspace))) { + STATE(stats).nl_events_filtered++; + goto out; + } + + origin_type = origin_find(nlh); + + switch(type) { + case NFCT_T_NEW: + STATE(mode)->internal->ct.new(ct, origin_type); + break; + case NFCT_T_UPDATE: + STATE(mode)->internal->ct.upd(ct, origin_type); + break; + case NFCT_T_DESTROY: + if (STATE(mode)->internal->ct.del(ct, origin_type)) + update_traffic_stats(ct); + break; + default: + STATE(stats).nl_events_unknown_type++; + break; + } + +out: + /* we reset the iteration limiter in the main select loop. */ + if (STATE(event_iterations_limit)-- <= 0) + return NFCT_CB_STOP; + else + return NFCT_CB_CONTINUE; +} + +static int exp_event_handler(const struct nlmsghdr *nlh, + enum nf_conntrack_msg_type type, + struct nf_expect *exp, + void *data) +{ + int origin_type; + const struct nf_conntrack *master = + nfexp_get_attr(exp, ATTR_EXP_MASTER); + + STATE(stats).nl_events_received++; + + if (!exp_filter_find(STATE(exp_filter), exp)) { + STATE(stats).nl_events_filtered++; + goto out; + } + if (ct_filter_master(master)) + return NFCT_CB_CONTINUE; + + origin_type = origin_find(nlh); + + switch(type) { + case NFCT_T_NEW: + STATE(mode)->internal->exp.new(exp, origin_type); + break; + case NFCT_T_UPDATE: + STATE(mode)->internal->exp.upd(exp, origin_type); + break; + case NFCT_T_DESTROY: + STATE(mode)->internal->exp.del(exp, origin_type); + break; + default: + STATE(stats).nl_events_unknown_type++; + break; + } + +out: + /* we reset the iteration limiter in the main select loop. */ + if (STATE(event_iterations_limit)-- <= 0) + return NFCT_CB_STOP; + else + return NFCT_CB_CONTINUE; +} + +static int dump_handler(enum nf_conntrack_msg_type type, + struct nf_conntrack *ct, + void *data) +{ + if (ct_filter_conntrack(ct, 1)) + return NFCT_CB_CONTINUE; + + switch(type) { + case NFCT_T_UPDATE: + STATE(mode)->internal->ct.populate(ct); + break; + default: + STATE(stats).nl_dump_unknown_type++; + break; + } + return NFCT_CB_CONTINUE; +} + +static int exp_dump_handler(enum nf_conntrack_msg_type type, + struct nf_expect *exp, void *data) +{ + const struct nf_conntrack *master = + nfexp_get_attr(exp, ATTR_EXP_MASTER); + + if (!exp_filter_find(STATE(exp_filter), exp)) + return NFCT_CB_CONTINUE; + + if (ct_filter_master(master)) + return NFCT_CB_CONTINUE; + + switch(type) { + case NFCT_T_UPDATE: + STATE(mode)->internal->exp.populate(exp); + break; + default: + STATE(stats).nl_dump_unknown_type++; + break; + } + return NFCT_CB_CONTINUE; +} + +static int get_handler(enum nf_conntrack_msg_type type, + struct nf_conntrack *ct, + void *data) +{ + if (ct_filter_conntrack(ct, 1)) + return NFCT_CB_CONTINUE; + + STATE(get_retval) = 1; + return NFCT_CB_CONTINUE; +} + +static int exp_get_handler(enum nf_conntrack_msg_type type, + struct nf_expect *exp, void *data) +{ + const struct nf_conntrack *master = + nfexp_get_attr(exp, ATTR_EXP_MASTER); + + if (!exp_filter_find(STATE(exp_filter), exp)) + return NFCT_CB_CONTINUE; + + if (ct_filter_master(master)) + return NFCT_CB_CONTINUE; + + STATE(get_retval) = 1; + return NFCT_CB_CONTINUE; +} + +/* we have received an event from ctnetlink */ +static void event_cb(void *data) +{ + int ret; + + ret = nfct_catch(STATE(event)); + /* reset event iteration limit counter */ + STATE(event_iterations_limit) = CONFIG(event_iterations_limit); + if (ret == -1) { + switch(errno) { + case ENOBUFS: + /* We have hit ENOBUFS, it's likely that we are + * losing events. Two possible situations may + * trigger this error: + * + * 1) The netlink receiver buffer is too small: + * increasing the netlink buffer size should + * be enough. However, some event messages + * got lost. We have to resync ourselves + * with the kernel table conntrack table to + * resolve the inconsistency. + * + * 2) The receiver is too slow to process the + * netlink messages so that the queue gets + * full quickly. This generally happens + * if the system is under heavy workload + * (busy CPU). In this case, increasing the + * size of the netlink receiver buffer + * would not help anymore since we would + * be delaying the overrun. Moreover, we + * should avoid resynchronizations. We + * should do our best here and keep + * replicating as much states as possible. + * If workload lowers at some point, + * we resync ourselves. + */ + nl_resize_socket_buffer(STATE(event)); + if (CONFIG(nl_overrun_resync) > 0 && + STATE(mode)->internal->flags & INTERNAL_F_RESYNC) { + add_alarm(&STATE(resync_alarm), + CONFIG(nl_overrun_resync),0); + } + STATE(stats).nl_catch_event_failed++; + STATE(stats).nl_overrun++; + break; + case ENOENT: + /* + * We received a message from another + * netfilter subsystem that we are not + * interested in. Just ignore it. + */ + break; + case EAGAIN: + /* No more events to receive, try later. */ + break; + default: + STATE(stats).nl_catch_event_failed++; + break; + } + } +} + +/* we previously requested a resync due to buffer overrun. */ +static void resync_cb(void *data) +{ + nfct_catch(STATE(resync)); + if (STATE(mode)->internal->ct.purge) + STATE(mode)->internal->ct.purge(); +} + +static void poll_cb(void *data) +{ + nfct_catch(STATE(resync)); +} + +int ctnl_init(void) +{ + if (CONFIG(flags) & CTD_STATS_MODE) + STATE(mode) = &stats_mode; + else if (CONFIG(flags) & CTD_SYNC_MODE) + STATE(mode) = &sync_mode; + else { + fprintf(stderr, "WARNING: No running mode specified. " + "Defaulting to statistics mode.\n"); + CONFIG(flags) |= CTD_STATS_MODE; + STATE(mode) = &stats_mode; + } + + /* Initialization */ + if (STATE(mode)->init() == -1) { + dlog(LOG_ERR, "initialization failed"); + return -1; + } + + /* resynchronize (like 'dump' socket) but it also purges old entries */ + STATE(resync) = nfct_open(CONFIG(netlink).subsys_id, 0); + if (STATE(resync)== NULL) { + dlog(LOG_ERR, "can't open netlink handler: %s", + strerror(errno)); + dlog(LOG_ERR, "no ctnetlink kernel support?"); + return -1; + } + nfct_callback_register(STATE(resync), + NFCT_T_ALL, + STATE(mode)->internal->ct.resync, + NULL); + if (CONFIG(flags) & CTD_POLL) { + register_fd(nfct_fd(STATE(resync)), poll_cb, + NULL, STATE(fds)); + } else { + register_fd(nfct_fd(STATE(resync)), resync_cb, + NULL, STATE(fds)); + } + fcntl(nfct_fd(STATE(resync)), F_SETFL, O_NONBLOCK); + + if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) { + STATE(dump) = nfct_open(CONFIG(netlink).subsys_id, 0); + if (STATE(dump) == NULL) { + dlog(LOG_ERR, "can't open netlink handler: %s", + strerror(errno)); + dlog(LOG_ERR, "no ctnetlink kernel support?"); + return -1; + } + nfct_callback_register(STATE(dump), NFCT_T_ALL, + dump_handler, NULL); + + if (CONFIG(flags) & CTD_EXPECT) { + nfexp_callback_register(STATE(dump), NFCT_T_ALL, + exp_dump_handler, NULL); + } + + if (nl_dump_conntrack_table(STATE(dump)) == -1) { + dlog(LOG_ERR, "can't get kernel conntrack table"); + return -1; + } + + if (CONFIG(flags) & CTD_EXPECT) { + if (nl_dump_expect_table(STATE(dump)) == -1) { + dlog(LOG_ERR, "can't get kernel " + "expect table"); + return -1; + } + } + } + + STATE(get) = nfct_open(CONFIG(netlink).subsys_id, 0); + if (STATE(get) == NULL) { + dlog(LOG_ERR, "can't open netlink handler: %s", + strerror(errno)); + dlog(LOG_ERR, "no ctnetlink kernel support?"); + return -1; + } + nfct_callback_register(STATE(get), NFCT_T_ALL, get_handler, NULL); + + if (CONFIG(flags) & CTD_EXPECT) { + nfexp_callback_register(STATE(get), NFCT_T_ALL, + exp_get_handler, NULL); + } + + STATE(flush) = nfct_open(CONFIG(netlink).subsys_id, 0); + if (STATE(flush) == NULL) { + dlog(LOG_ERR, "cannot open flusher handler"); + return -1; + } + /* register this handler as the origin of a flush operation */ + origin_register(STATE(flush), CTD_ORIGIN_FLUSH); + + if (CONFIG(flags) & CTD_POLL) { + init_alarm(&STATE(polling_alarm), NULL, do_polling_alarm); + add_alarm(&STATE(polling_alarm), CONFIG(poll_kernel_secs), 0); + dlog(LOG_NOTICE, "running in polling mode"); + } else { + init_alarm(&STATE(resync_alarm), NULL, do_overrun_resync_alarm); + /* + * The last nfct handler that we register is the event handler. + * The reason to do this is that we may receive events while + * populating the internal cache. Thus, we hit ENOBUFS + * prematurely. However, if we open the event handler before + * populating the internal cache, we may still lose events + * that have occured during the population. + */ + STATE(event) = nl_init_event_handler(); + if (STATE(event) == NULL) { + dlog(LOG_ERR, "can't open netlink handler: %s", + strerror(errno)); + dlog(LOG_ERR, "no ctnetlink kernel support?"); + return -1; + } + nfct_callback_register2(STATE(event), NFCT_T_ALL, + event_handler, NULL); + + if (CONFIG(flags) & CTD_EXPECT) { + nfexp_callback_register2(STATE(event), NFCT_T_ALL, + exp_event_handler, NULL); + } + register_fd(nfct_fd(STATE(event)), event_cb, NULL, STATE(fds)); + } + + return 0; +} |