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415 lines
15 KiB
415 lines
15 KiB
7 years ago
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Adapted version of
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commit 999eaa241212d3952ddff39a99d0d55a74e3639e
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Author: Lorenzo Colitti <lorenzo@google.com>
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Date: Thu Mar 16 16:55:02 2017 +0900
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iptables-restore: support acquiring the lock.
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Currently, ip[6]tables-restore does not perform any locking, so it
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is not safe to use concurrently with ip[6]tables.
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This patch makes ip[6]tables-restore wait for the lock if -w
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was specified. Arguments to -w and -W are supported in the same
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was as they are in ip[6]tables.
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The lock is not acquired on startup. Instead, it is acquired when
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a new table handle is created (on encountering '*') and released
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when the table is committed (COMMIT). This makes it possible to
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keep long-running iptables-restore processes in the background
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(for example, reading commands from a pipe opened by a system
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management daemon) and simultaneously run iptables commands.
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If -w is not specified, then the command proceeds without taking
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the lock.
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Tested as follows:
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1. Run iptables-restore -w, and check that iptables commands work
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with or without -w.
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2. Type "*filter" into the iptables-restore input. Verify that
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a) ip[6]tables commands without -w fail with "another app is
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currently holding the xtables lock...".
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b) ip[6]tables commands with "-w 2" fail after 2 seconds.
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c) ip[6]tables commands with "-w" hang until "COMMIT" is
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typed into the iptables-restore window.
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3. With the lock held by an ip6tables-restore process:
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strace -e flock /tmp/iptables/sbin/iptables-restore -w 1 -W 100000
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shows 11 calls to flock and fails.
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4. Run an iptables-restore with -w and one without -w, and check:
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a) Type "*filter" in the first and then the second, and the
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second exits with an error.
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b) Type "*filter" in the second and "*filter" "-S" "COMMIT"
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into the first. The rules are listed only when the first
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copy sees "COMMIT".
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Signed-off-by: Narayan Kamath <narayan@google.com>
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Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
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Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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diff -up iptables-1.4.21/iptables/ip6tables.c.restore_support_acquiring_the_lock iptables-1.4.21/iptables/ip6tables.c
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--- iptables-1.4.21/iptables/ip6tables.c.restore_support_acquiring_the_lock 2017-04-05 14:55:52.561008864 +0200
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+++ iptables-1.4.21/iptables/ip6tables.c 2017-04-05 14:55:52.564008888 +0200
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@@ -1767,7 +1767,7 @@ int do_command6(int argc, char *argv[],
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generic_opt_check(command, cs.options);
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/* Attempt to acquire the xtables lock */
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- if (!restore && !xtables_lock(wait, &wait_interval)) {
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+ if (!restore && xtables_lock(wait, &wait_interval) == XT_LOCK_BUSY) {
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fprintf(stderr, "Another app is currently holding the xtables lock. ");
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if (wait == 0)
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fprintf(stderr, "Perhaps you want to use the -w option?\n");
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diff -up iptables-1.4.21/iptables/ip6tables-restore.c.restore_support_acquiring_the_lock iptables-1.4.21/iptables/ip6tables-restore.c
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--- iptables-1.4.21/iptables/ip6tables-restore.c.restore_support_acquiring_the_lock 2013-11-22 12:18:13.000000000 +0100
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+++ iptables-1.4.21/iptables/ip6tables-restore.c 2017-04-05 14:58:41.513393942 +0200
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@@ -15,6 +15,7 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include "ip6tables.h"
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+#include "xshared.h"
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#include "xtables.h"
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#include "libiptc/libip6tc.h"
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#include "ip6tables-multi.h"
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@@ -25,18 +26,24 @@
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#define DEBUGP(x, args...)
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#endif
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-static int binary = 0, counters = 0, verbose = 0, noflush = 0;
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+static int binary = 0, counters = 0, verbose = 0, noflush = 0, wait = 0;
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+
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+static struct timeval wait_interval = {
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+ .tv_sec = 1,
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+};
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/* Keeping track of external matches and targets. */
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static const struct option options[] = {
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- {.name = "binary", .has_arg = false, .val = 'b'},
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- {.name = "counters", .has_arg = false, .val = 'c'},
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- {.name = "verbose", .has_arg = false, .val = 'v'},
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- {.name = "test", .has_arg = false, .val = 't'},
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- {.name = "help", .has_arg = false, .val = 'h'},
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- {.name = "noflush", .has_arg = false, .val = 'n'},
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- {.name = "modprobe", .has_arg = true, .val = 'M'},
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- {.name = "table", .has_arg = true, .val = 'T'},
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+ {.name = "binary", .has_arg = 0, .val = 'b'},
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+ {.name = "counters", .has_arg = 0, .val = 'c'},
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+ {.name = "verbose", .has_arg = 0, .val = 'v'},
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+ {.name = "test", .has_arg = 0, .val = 't'},
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+ {.name = "help", .has_arg = 0, .val = 'h'},
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+ {.name = "noflush", .has_arg = 0, .val = 'n'},
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+ {.name = "modprobe", .has_arg = 1, .val = 'M'},
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+ {.name = "table", .has_arg = 1, .val = 'T'},
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+ {.name = "wait", .has_arg = 2, .val = 'w'},
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+ {.name = "wait-interval", .has_arg = 2, .val = 'W'},
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{NULL},
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};
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@@ -44,14 +51,16 @@ static void print_usage(const char *name
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static void print_usage(const char *name, const char *version)
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{
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- fprintf(stderr, "Usage: %s [-b] [-c] [-v] [-t] [-h]\n"
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+ fprintf(stderr, "Usage: %s [-b] [-c] [-v] [-t] [-h] [-w secs] [-W usecs]\n"
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" [ --binary ]\n"
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" [ --counters ]\n"
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" [ --verbose ]\n"
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" [ --test ]\n"
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" [ --help ]\n"
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+ " [ --wait=<seconds>\n"
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+ " [ --wait-interval=<usecs>\n"
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" [ --noflush ]\n"
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- " [ --modprobe=<command>]\n", name);
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+ " [ --modprobe=<command>]\n", name);
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exit(1);
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}
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@@ -182,7 +191,7 @@ int ip6tables_restore_main(int argc, cha
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{
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struct xtc_handle *handle = NULL;
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char buffer[10240];
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- int c;
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+ int c, lock;
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char curtable[XT_TABLE_MAXNAMELEN + 1];
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FILE *in;
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int in_table = 0, testing = 0;
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@@ -190,6 +199,7 @@ int ip6tables_restore_main(int argc, cha
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const struct xtc_ops *ops = &ip6tc_ops;
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line = 0;
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+ lock = XT_LOCK_NOT_ACQUIRED;
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ip6tables_globals.program_name = "ip6tables-restore";
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c = xtables_init_all(&ip6tables_globals, NFPROTO_IPV6);
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@@ -204,7 +214,7 @@ int ip6tables_restore_main(int argc, cha
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init_extensions6();
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#endif
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- while ((c = getopt_long(argc, argv, "bcvthnM:T:", options, NULL)) != -1) {
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+ while ((c = getopt_long(argc, argv, "bcvthnwWM:T:", options, NULL)) != -1) {
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switch (c) {
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case 'b':
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binary = 1;
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@@ -225,6 +235,12 @@ int ip6tables_restore_main(int argc, cha
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case 'n':
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noflush = 1;
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break;
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+ case 'w':
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+ wait = parse_wait_time(argc, argv);
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+ break;
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+ case 'W':
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+ parse_wait_interval(argc, argv, &wait_interval);
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+ break;
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case 'M':
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xtables_modprobe_program = optarg;
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break;
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@@ -269,8 +285,23 @@ int ip6tables_restore_main(int argc, cha
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DEBUGP("Not calling commit, testing\n");
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ret = 1;
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}
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+
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+ /* Done with the current table, release the lock. */
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+ if (lock >= 0) {
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+ xtables_unlock(lock);
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+ lock = XT_LOCK_NOT_ACQUIRED;
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+ }
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+
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in_table = 0;
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} else if ((buffer[0] == '*') && (!in_table)) {
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+ /* Acquire a lock before we create a new table handle */
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+ lock = xtables_lock(wait, &wait_interval);
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+ if (lock == XT_LOCK_BUSY) {
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+ fprintf(stderr, "Another app is currently holding the xtables lock. "
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+ "Perhaps you want to use the -w option?\n");
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+ exit(RESOURCE_PROBLEM);
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+ }
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+
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/* New table */
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char *table;
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diff -up iptables-1.4.21/iptables/iptables.c.restore_support_acquiring_the_lock iptables-1.4.21/iptables/iptables.c
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--- iptables-1.4.21/iptables/iptables.c.restore_support_acquiring_the_lock 2017-04-05 14:55:52.562008872 +0200
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+++ iptables-1.4.21/iptables/iptables.c 2017-04-05 14:55:52.564008888 +0200
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@@ -1754,7 +1754,7 @@ int do_command4(int argc, char *argv[],
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generic_opt_check(command, cs.options);
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/* Attempt to acquire the xtables lock */
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- if (!restore && !xtables_lock(wait, &wait_interval)) {
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+ if (!restore && xtables_lock(wait, &wait_interval) == XT_LOCK_BUSY) {
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fprintf(stderr, "Another app is currently holding the xtables lock. ");
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if (wait == 0)
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fprintf(stderr, "Perhaps you want to use the -w option?\n");
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diff -up iptables-1.4.21/iptables/iptables-restore.c.restore_support_acquiring_the_lock iptables-1.4.21/iptables/iptables-restore.c
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--- iptables-1.4.21/iptables/iptables-restore.c.restore_support_acquiring_the_lock 2013-11-22 12:18:13.000000000 +0100
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+++ iptables-1.4.21/iptables/iptables-restore.c 2017-04-05 15:00:17.389179935 +0200
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@@ -12,6 +12,7 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include "iptables.h"
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+#include "xshared.h"
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#include "xtables.h"
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#include "libiptc/libiptc.h"
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#include "iptables-multi.h"
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@@ -22,18 +23,24 @@
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#define DEBUGP(x, args...)
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#endif
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-static int binary = 0, counters = 0, verbose = 0, noflush = 0;
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+static int binary = 0, counters = 0, verbose = 0, noflush = 0, wait = 0;
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+
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+static struct timeval wait_interval = {
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+ .tv_sec = 1,
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+};
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/* Keeping track of external matches and targets. */
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static const struct option options[] = {
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- {.name = "binary", .has_arg = false, .val = 'b'},
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- {.name = "counters", .has_arg = false, .val = 'c'},
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- {.name = "verbose", .has_arg = false, .val = 'v'},
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- {.name = "test", .has_arg = false, .val = 't'},
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- {.name = "help", .has_arg = false, .val = 'h'},
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- {.name = "noflush", .has_arg = false, .val = 'n'},
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- {.name = "modprobe", .has_arg = true, .val = 'M'},
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- {.name = "table", .has_arg = true, .val = 'T'},
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+ {.name = "binary", .has_arg = 0, .val = 'b'},
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+ {.name = "counters", .has_arg = 0, .val = 'c'},
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+ {.name = "verbose", .has_arg = 0, .val = 'v'},
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+ {.name = "test", .has_arg = 0, .val = 't'},
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+ {.name = "help", .has_arg = 0, .val = 'h'},
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+ {.name = "noflush", .has_arg = 0, .val = 'n'},
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+ {.name = "modprobe", .has_arg = 1, .val = 'M'},
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+ {.name = "table", .has_arg = 1, .val = 'T'},
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+ {.name = "wait", .has_arg = 2, .val = 'w'},
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+ {.name = "wait-interval", .has_arg = 2, .val = 'W'},
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{NULL},
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};
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@@ -43,15 +50,17 @@ static void print_usage(const char *name
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static void print_usage(const char *name, const char *version)
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{
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- fprintf(stderr, "Usage: %s [-b] [-c] [-v] [-t] [-h]\n"
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+ fprintf(stderr, "Usage: %s [-b] [-c] [-v] [-t] [-h] [-W usecs]\n"
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" [ --binary ]\n"
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" [ --counters ]\n"
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" [ --verbose ]\n"
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" [ --test ]\n"
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" [ --help ]\n"
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" [ --noflush ]\n"
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+ " [ --wait=<seconds>\n"
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+ " [ --wait-interval=<usecs>\n"
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" [ --table=<TABLE> ]\n"
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- " [ --modprobe=<command>]\n", name);
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+ " [ --modprobe=<command>]\n", name);
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exit(1);
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}
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@@ -182,7 +191,7 @@ iptables_restore_main(int argc, char *ar
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{
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struct xtc_handle *handle = NULL;
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char buffer[10240];
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- int c;
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+ int c, lock;
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char curtable[XT_TABLE_MAXNAMELEN + 1];
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FILE *in;
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int in_table = 0, testing = 0;
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@@ -190,6 +199,7 @@ iptables_restore_main(int argc, char *ar
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const struct xtc_ops *ops = &iptc_ops;
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line = 0;
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+ lock = XT_LOCK_NOT_ACQUIRED;
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iptables_globals.program_name = "iptables-restore";
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c = xtables_init_all(&iptables_globals, NFPROTO_IPV4);
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@@ -204,7 +214,7 @@ iptables_restore_main(int argc, char *ar
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init_extensions4();
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#endif
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- while ((c = getopt_long(argc, argv, "bcvthnM:T:", options, NULL)) != -1) {
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+ while ((c = getopt_long(argc, argv, "bcvthnwWM:T:", options, NULL)) != -1) {
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switch (c) {
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case 'b':
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binary = 1;
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@@ -225,6 +235,12 @@ iptables_restore_main(int argc, char *ar
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case 'n':
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noflush = 1;
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break;
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+ case 'w':
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+ wait = parse_wait_time(argc, argv);
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+ break;
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+ case 'W':
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+ parse_wait_interval(argc, argv, &wait_interval);
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+ break;
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case 'M':
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xtables_modprobe_program = optarg;
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break;
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|
|
@@ -269,8 +285,23 @@ iptables_restore_main(int argc, char *ar
|
||
|
|
DEBUGP("Not calling commit, testing\n");
|
||
|
|
ret = 1;
|
||
|
|
}
|
||
|
|
+
|
||
|
|
+ /* Done with the current table, release the lock. */
|
||
|
|
+ if (lock >= 0) {
|
||
|
|
+ xtables_unlock(lock);
|
||
|
|
+ lock = XT_LOCK_NOT_ACQUIRED;
|
||
|
|
+ }
|
||
|
|
+
|
||
|
|
in_table = 0;
|
||
|
|
} else if ((buffer[0] == '*') && (!in_table)) {
|
||
|
|
+ /* Acquire a lock before we create a new table handle */
|
||
|
|
+ lock = xtables_lock(wait, &wait_interval);
|
||
|
|
+ if (lock == XT_LOCK_BUSY) {
|
||
|
|
+ fprintf(stderr, "Another app is currently holding the xtables lock. "
|
||
|
|
+ "Perhaps you want to use the -w option?\n");
|
||
|
|
+ exit(RESOURCE_PROBLEM);
|
||
|
|
+ }
|
||
|
|
+
|
||
|
|
/* New table */
|
||
|
|
char *table;
|
||
|
|
|
||
|
|
diff -up iptables-1.4.21/iptables/xshared.c.restore_support_acquiring_the_lock iptables-1.4.21/iptables/xshared.c
|
||
|
|
--- iptables-1.4.21/iptables/xshared.c.restore_support_acquiring_the_lock 2017-04-05 14:55:52.562008872 +0200
|
||
|
|
+++ iptables-1.4.21/iptables/xshared.c 2017-04-05 14:55:52.565008896 +0200
|
||
|
|
@@ -246,7 +246,7 @@ void xs_init_match(struct xtables_match
|
||
|
|
match->init(match->m);
|
||
|
|
}
|
||
|
|
|
||
|
|
-bool xtables_lock(int wait, struct timeval *wait_interval)
|
||
|
|
+int xtables_lock(int wait, struct timeval *wait_interval)
|
||
|
|
{
|
||
|
|
struct timeval time_left, wait_time;
|
||
|
|
int fd, i = 0;
|
||
|
|
@@ -256,22 +256,22 @@ bool xtables_lock(int wait, struct timev
|
||
|
|
|
||
|
|
fd = open(XT_LOCK_NAME, O_CREAT, 0600);
|
||
|
|
if (fd < 0)
|
||
|
|
- return true;
|
||
|
|
+ return XT_LOCK_UNSUPPORTED;
|
||
|
|
|
||
|
|
if (wait == -1) {
|
||
|
|
if (flock(fd, LOCK_EX) == 0)
|
||
|
|
- return true;
|
||
|
|
+ return fd;
|
||
|
|
|
||
|
|
fprintf(stderr, "Can't lock %s: %s\n", XT_LOCK_NAME,
|
||
|
|
strerror(errno));
|
||
|
|
- return false;
|
||
|
|
+ return XT_LOCK_BUSY;
|
||
|
|
}
|
||
|
|
|
||
|
|
while (1) {
|
||
|
|
if (flock(fd, LOCK_EX | LOCK_NB) == 0)
|
||
|
|
- return true;
|
||
|
|
+ return fd;
|
||
|
|
else if (timercmp(&time_left, wait_interval, <))
|
||
|
|
- return false;
|
||
|
|
+ return XT_LOCK_BUSY;
|
||
|
|
|
||
|
|
if (++i % 10 == 0) {
|
||
|
|
fprintf(stderr, "Another app is currently holding the xtables lock; "
|
||
|
|
@@ -285,6 +285,12 @@ bool xtables_lock(int wait, struct timev
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
+void xtables_unlock(int lock)
|
||
|
|
+{
|
||
|
|
+ if (lock >= 0)
|
||
|
|
+ close(lock);
|
||
|
|
+}
|
||
|
|
+
|
||
|
|
int parse_wait_time(int argc, char *argv[])
|
||
|
|
{
|
||
|
|
int wait = -1;
|
||
|
|
diff -up iptables-1.4.21/iptables/xshared.h.restore_support_acquiring_the_lock iptables-1.4.21/iptables/xshared.h
|
||
|
|
--- iptables-1.4.21/iptables/xshared.h.restore_support_acquiring_the_lock 2017-04-05 14:55:52.562008872 +0200
|
||
|
|
+++ iptables-1.4.21/iptables/xshared.h 2017-04-05 14:55:52.565008896 +0200
|
||
|
|
@@ -84,7 +84,28 @@ extern struct xtables_match *load_proto(
|
||
|
|
extern int subcmd_main(int, char **, const struct subcommand *);
|
||
|
|
extern void xs_init_target(struct xtables_target *);
|
||
|
|
extern void xs_init_match(struct xtables_match *);
|
||
|
|
-bool xtables_lock(int wait, struct timeval *wait_interval);
|
||
|
|
+
|
||
|
|
+/**
|
||
|
|
+ * Values for the iptables lock.
|
||
|
|
+ *
|
||
|
|
+ * A value >= 0 indicates the lock filedescriptor. Other values are:
|
||
|
|
+ *
|
||
|
|
+ * XT_LOCK_UNSUPPORTED : The system does not support locking, execution will
|
||
|
|
+ * proceed lockless.
|
||
|
|
+ *
|
||
|
|
+ * XT_LOCK_BUSY : The lock was held by another process. xtables_lock only
|
||
|
|
+ * returns this value when |wait| == false. If |wait| == true, xtables_lock
|
||
|
|
+ * will not return unless the lock has been acquired.
|
||
|
|
+ *
|
||
|
|
+ * XT_LOCK_NOT_ACQUIRED : We have not yet attempted to acquire the lock.
|
||
|
|
+ */
|
||
|
|
+enum {
|
||
|
|
+ XT_LOCK_BUSY = -1,
|
||
|
|
+ XT_LOCK_UNSUPPORTED = -2,
|
||
|
|
+ XT_LOCK_NOT_ACQUIRED = -3,
|
||
|
|
+};
|
||
|
|
+extern int xtables_lock(int wait, struct timeval *tv);
|
||
|
|
+extern void xtables_unlock(int lock);
|
||
|
|
|
||
|
|
int parse_wait_time(int argc, char *argv[]);
|
||
|
|
void parse_wait_interval(int argc, char *argv[], struct timeval *wait_interval);
|