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selftests: netfilter: Test nf_tables audit logging
Compare NETFILTER_CFG type audit logs emitted from kernel upon ruleset modifications against expected output. Signed-off-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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‎tools/testing/selftests/netfilter/.gitignore‎

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# SPDX-License-Identifier: GPL-2.0-only
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nf-queue
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connect_close
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audit_logread

‎tools/testing/selftests/netfilter/Makefile‎

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@@ -6,13 +6,13 @@ TEST_PROGS := nft_trans_stress.sh nft_fib.sh nft_nat.sh bridge_brouter.sh \
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nft_concat_range.sh nft_conntrack_helper.sh \
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nft_queue.sh nft_meta.sh nf_nat_edemux.sh \
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ipip-conntrack-mtu.sh conntrack_tcp_unreplied.sh \
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conntrack_vrf.sh nft_synproxy.sh rpath.sh
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conntrack_vrf.sh nft_synproxy.sh rpath.sh nft_audit.sh
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HOSTPKG_CONFIG := pkg-config
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CFLAGS += $(shell $(HOSTPKG_CONFIG) --cflags libmnl 2>/dev/null)
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LDLIBS += $(shell $(HOSTPKG_CONFIG) --libs libmnl 2>/dev/null || echo -lmnl)
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TEST_GEN_FILES = nf-queue connect_close
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TEST_GEN_FILES = nf-queue connect_close audit_logread
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include ../lib.mk

‎tools/testing/selftests/netfilter/audit_logread.c‎

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// SPDX-License-Identifier: GPL-2.0
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#define _GNU_SOURCE
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <signal.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <unistd.h>
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#include <linux/audit.h>
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#include <linux/netlink.h>
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static int fd;
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#define MAX_AUDIT_MESSAGE_LENGTH 8970
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struct audit_message {
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struct nlmsghdr nlh;
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union {
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struct audit_status s;
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char data[MAX_AUDIT_MESSAGE_LENGTH];
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} u;
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};
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int audit_recv(int fd, struct audit_message *rep)
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{
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struct sockaddr_nl addr;
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socklen_t addrlen = sizeof(addr);
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int ret;
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do {
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ret = recvfrom(fd, rep, sizeof(*rep), 0,
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(struct sockaddr *)&addr, &addrlen);
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} while (ret < 0 && errno == EINTR);
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if (ret < 0 ||
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addrlen != sizeof(addr) ||
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addr.nl_pid != 0 ||
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rep->nlh.nlmsg_type == NLMSG_ERROR) /* short-cut for now */
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return -1;
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return ret;
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}
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int audit_send(int fd, uint16_t type, uint32_t key, uint32_t val)
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{
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static int seq = 0;
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struct audit_message msg = {
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.nlh = {
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.nlmsg_len = NLMSG_SPACE(sizeof(msg.u.s)),
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.nlmsg_type = type,
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.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
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.nlmsg_seq = ++seq,
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},
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.u.s = {
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.mask = key,
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.enabled = key == AUDIT_STATUS_ENABLED ? val : 0,
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.pid = key == AUDIT_STATUS_PID ? val : 0,
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}
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};
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struct sockaddr_nl addr = {
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.nl_family = AF_NETLINK,
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};
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int ret;
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do {
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ret = sendto(fd, &msg, msg.nlh.nlmsg_len, 0,
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(struct sockaddr *)&addr, sizeof(addr));
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} while (ret < 0 && errno == EINTR);
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if (ret != (int)msg.nlh.nlmsg_len)
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return -1;
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return 0;
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}
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int audit_set(int fd, uint32_t key, uint32_t val)
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{
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struct audit_message rep = { 0 };
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int ret;
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ret = audit_send(fd, AUDIT_SET, key, val);
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if (ret)
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return ret;
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ret = audit_recv(fd, &rep);
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if (ret < 0)
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return ret;
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return 0;
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}
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int readlog(int fd)
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{
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struct audit_message rep = { 0 };
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int ret = audit_recv(fd, &rep);
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const char *sep = "";
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char *k, *v;
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if (ret < 0)
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return ret;
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if (rep.nlh.nlmsg_type != AUDIT_NETFILTER_CFG)
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return 0;
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/* skip the initial "audit(...): " part */
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strtok(rep.u.data, " ");
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while ((k = strtok(NULL, "="))) {
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v = strtok(NULL, " ");
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/* these vary and/or are uninteresting, ignore */
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if (!strcmp(k, "pid") ||
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!strcmp(k, "comm") ||
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!strcmp(k, "subj"))
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continue;
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/* strip the varying sequence number */
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if (!strcmp(k, "table"))
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*strchrnul(v, ':') = '\0';
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printf("%s%s=%s", sep, k, v);
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sep = " ";
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}
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if (*sep) {
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printf("\n");
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fflush(stdout);
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}
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return 0;
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}
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void cleanup(int sig)
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{
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audit_set(fd, AUDIT_STATUS_ENABLED, 0);
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close(fd);
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if (sig)
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exit(0);
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}
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int main(int argc, char **argv)
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{
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struct sigaction act = {
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.sa_handler = cleanup,
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};
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fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_AUDIT);
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if (fd < 0) {
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perror("Can't open netlink socket");
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return -1;
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}
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if (sigaction(SIGTERM, &act, NULL) < 0 ||
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sigaction(SIGINT, &act, NULL) < 0) {
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perror("Can't set signal handler");
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close(fd);
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return -1;
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}
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audit_set(fd, AUDIT_STATUS_ENABLED, 1);
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audit_set(fd, AUDIT_STATUS_PID, getpid());
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while (1)
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readlog(fd);
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}

‎tools/testing/selftests/netfilter/config‎

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@@ -6,3 +6,4 @@ CONFIG_NFT_REDIR=m
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CONFIG_NFT_MASQ=m
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CONFIG_NFT_FLOW_OFFLOAD=m
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CONFIG_NF_CT_NETLINK=m
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CONFIG_AUDIT=y

‎tools/testing/selftests/netfilter/nft_audit.sh‎

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#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0
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#
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# Check that audit logs generated for nft commands are as expected.
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SKIP_RC=4
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RC=0
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nft --version >/dev/null 2>&1 || {
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echo "SKIP: missing nft tool"
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exit $SKIP_RC
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}
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logfile=$(mktemp)
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echo "logging into $logfile"
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./audit_logread >"$logfile" &
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logread_pid=$!
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trap 'kill $logread_pid; rm -f $logfile' EXIT
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exec 3<"$logfile"
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do_test() { # (cmd, log)
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echo -n "testing for cmd: $1 ... "
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cat <&3 >/dev/null
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$1 >/dev/null || exit 1
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sleep 0.1
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res=$(diff -a -u <(echo "$2") - <&3)
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[ $? -eq 0 ] && { echo "OK"; return; }
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echo "FAIL"
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echo "$res"
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((RC++))
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}
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nft flush ruleset
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for table in t1 t2; do
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do_test "nft add table $table" \
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"table=$table family=2 entries=1 op=nft_register_table"
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do_test "nft add chain $table c1" \
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"table=$table family=2 entries=1 op=nft_register_chain"
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do_test "nft add chain $table c2; add chain $table c3" \
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"table=$table family=2 entries=2 op=nft_register_chain"
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cmd="add rule $table c1 counter"
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do_test "nft $cmd" \
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"table=$table family=2 entries=1 op=nft_register_rule"
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do_test "nft $cmd; $cmd" \
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"table=$table family=2 entries=2 op=nft_register_rule"
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cmd=""
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sep=""
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for chain in c2 c3; do
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for i in {1..3}; do
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cmd+="$sep add rule $table $chain counter"
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sep=";"
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done
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done
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do_test "nft $cmd" \
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"table=$table family=2 entries=6 op=nft_register_rule"
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done
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do_test 'nft reset rules t1 c2' \
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'table=t1 family=2 entries=3 op=nft_reset_rule'
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do_test 'nft reset rules table t1' \
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'table=t1 family=2 entries=3 op=nft_reset_rule
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table=t1 family=2 entries=3 op=nft_reset_rule
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table=t1 family=2 entries=3 op=nft_reset_rule'
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do_test 'nft reset rules' \
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'table=t1 family=2 entries=3 op=nft_reset_rule
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table=t1 family=2 entries=3 op=nft_reset_rule
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table=t1 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=3 op=nft_reset_rule'
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for ((i = 0; i < 500; i++)); do
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echo "add rule t2 c3 counter accept comment \"rule $i\""
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done | do_test 'nft -f -' \
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'table=t2 family=2 entries=500 op=nft_register_rule'
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do_test 'nft reset rules t2 c3' \
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'table=t2 family=2 entries=189 op=nft_reset_rule
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table=t2 family=2 entries=188 op=nft_reset_rule
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table=t2 family=2 entries=126 op=nft_reset_rule'
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do_test 'nft reset rules t2' \
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'table=t2 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=186 op=nft_reset_rule
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table=t2 family=2 entries=188 op=nft_reset_rule
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table=t2 family=2 entries=129 op=nft_reset_rule'
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do_test 'nft reset rules' \
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'table=t1 family=2 entries=3 op=nft_reset_rule
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table=t1 family=2 entries=3 op=nft_reset_rule
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table=t1 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=3 op=nft_reset_rule
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table=t2 family=2 entries=180 op=nft_reset_rule
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table=t2 family=2 entries=188 op=nft_reset_rule
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table=t2 family=2 entries=135 op=nft_reset_rule'
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exit $RC

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