Commit 7f204a7d authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller

selftests: net: Add SO_REUSEADDR test to check if 4-tuples are fully utilized.

This commit adds a test to check if we can fully utilize 4-tuples for
connect() when all ephemeral ports are exhausted.

The test program changes the local port range to use only one port and binds
two sockets with or without SO_REUSEADDR and SO_REUSEPORT, and with the same
EUID or with different EUIDs, then do listen().

We should be able to bind only one socket having both SO_REUSEADDR and
SO_REUSEPORT per EUID, which restriction is to prevent unintentional
listen().
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 33575921
......@@ -23,3 +23,4 @@ so_txtime
tcp_fastopen_backup_key
nettest
fin_ack_lat
reuseaddr_ports_exhausted
\ No newline at end of file
......@@ -12,6 +12,7 @@ TEST_PROGS += udpgro_bench.sh udpgro.sh test_vxlan_under_vrf.sh reuseport_addr_a
TEST_PROGS += test_vxlan_fdb_changelink.sh so_txtime.sh ipv6_flowlabel.sh
TEST_PROGS += tcp_fastopen_backup_key.sh fcnal-test.sh l2tp.sh traceroute.sh
TEST_PROGS += fin_ack_lat.sh
TEST_PROGS += reuseaddr_ports_exhausted.sh
TEST_PROGS_EXTENDED := in_netns.sh
TEST_GEN_FILES = socket nettest
TEST_GEN_FILES += psock_fanout psock_tpacket msg_zerocopy reuseport_addr_any
......@@ -22,6 +23,7 @@ TEST_GEN_FILES += tcp_fastopen_backup_key
TEST_GEN_FILES += fin_ack_lat
TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa
TEST_GEN_PROGS += reuseport_dualstack reuseaddr_conflict tls
TEST_GEN_FILES += reuseaddr_ports_exhausted
KSFT_KHDR_INSTALL := 1
include ../lib.mk
......
// SPDX-License-Identifier: GPL-2.0-only
/*
* Check if we can fully utilize 4-tuples for connect().
*
* Rules to bind sockets to the same port when all ephemeral ports are
* exhausted.
*
* 1. if there are TCP_LISTEN sockets on the port, fail to bind.
* 2. if there are sockets without SO_REUSEADDR, fail to bind.
* 3. if SO_REUSEADDR is disabled, fail to bind.
* 4. if SO_REUSEADDR is enabled and SO_REUSEPORT is disabled,
* succeed to bind.
* 5. if SO_REUSEADDR and SO_REUSEPORT are enabled and
* there is no socket having the both options and the same EUID,
* succeed to bind.
* 6. fail to bind.
*
* Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
*/
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include "../kselftest_harness.h"
struct reuse_opts {
int reuseaddr[2];
int reuseport[2];
};
struct reuse_opts unreusable_opts[12] = {
{0, 0, 0, 0},
{0, 0, 0, 1},
{0, 0, 1, 0},
{0, 0, 1, 1},
{0, 1, 0, 0},
{0, 1, 0, 1},
{0, 1, 1, 0},
{0, 1, 1, 1},
{1, 0, 0, 0},
{1, 0, 0, 1},
{1, 0, 1, 0},
{1, 0, 1, 1},
};
struct reuse_opts reusable_opts[4] = {
{1, 1, 0, 0},
{1, 1, 0, 1},
{1, 1, 1, 0},
{1, 1, 1, 1},
};
int bind_port(struct __test_metadata *_metadata, int reuseaddr, int reuseport)
{
struct sockaddr_in local_addr;
int len = sizeof(local_addr);
int fd, ret;
fd = socket(AF_INET, SOCK_STREAM, 0);
ASSERT_NE(-1, fd) TH_LOG("failed to open socket.");
ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuseaddr, sizeof(int));
ASSERT_EQ(0, ret) TH_LOG("failed to setsockopt: SO_REUSEADDR.");
ret = setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &reuseport, sizeof(int));
ASSERT_EQ(0, ret) TH_LOG("failed to setsockopt: SO_REUSEPORT.");
local_addr.sin_family = AF_INET;
local_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
local_addr.sin_port = 0;
if (bind(fd, (struct sockaddr *)&local_addr, len) == -1) {
close(fd);
return -1;
}
return fd;
}
TEST(reuseaddr_ports_exhausted_unreusable)
{
struct reuse_opts *opts;
int i, j, fd[2];
for (i = 0; i < 12; i++) {
opts = &unreusable_opts[i];
for (j = 0; j < 2; j++)
fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]);
ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind.");
EXPECT_EQ(-1, fd[1]) TH_LOG("should fail to bind.");
for (j = 0; j < 2; j++)
if (fd[j] != -1)
close(fd[j]);
}
}
TEST(reuseaddr_ports_exhausted_reusable_same_euid)
{
struct reuse_opts *opts;
int i, j, fd[2];
for (i = 0; i < 4; i++) {
opts = &reusable_opts[i];
for (j = 0; j < 2; j++)
fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]);
ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind.");
if (opts->reuseport[0] && opts->reuseport[1]) {
EXPECT_EQ(-1, fd[1]) TH_LOG("should fail to bind because both sockets succeed to be listened.");
} else {
EXPECT_NE(-1, fd[1]) TH_LOG("should succeed to bind to connect to different destinations.");
}
for (j = 0; j < 2; j++)
if (fd[j] != -1)
close(fd[j]);
}
}
TEST(reuseaddr_ports_exhausted_reusable_different_euid)
{
struct reuse_opts *opts;
int i, j, ret, fd[2];
uid_t euid[2] = {10, 20};
for (i = 0; i < 4; i++) {
opts = &reusable_opts[i];
for (j = 0; j < 2; j++) {
ret = seteuid(euid[j]);
ASSERT_EQ(0, ret) TH_LOG("failed to seteuid: %d.", euid[j]);
fd[j] = bind_port(_metadata, opts->reuseaddr[j], opts->reuseport[j]);
ret = seteuid(0);
ASSERT_EQ(0, ret) TH_LOG("failed to seteuid: 0.");
}
ASSERT_NE(-1, fd[0]) TH_LOG("failed to bind.");
EXPECT_NE(-1, fd[1]) TH_LOG("should succeed to bind because one socket can be bound in each euid.");
if (fd[1] != -1) {
ret = listen(fd[0], 5);
ASSERT_EQ(0, ret) TH_LOG("failed to listen.");
ret = listen(fd[1], 5);
EXPECT_EQ(-1, ret) TH_LOG("should fail to listen because only one uid reserves the port in TCP_LISTEN.");
}
for (j = 0; j < 2; j++)
if (fd[j] != -1)
close(fd[j]);
}
}
TEST_HARNESS_MAIN
#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
#
# Run tests when all ephemeral ports are exhausted.
#
# Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
set +x
set -e
readonly NETNS="ns-$(mktemp -u XXXXXX)"
setup() {
ip netns add "${NETNS}"
ip -netns "${NETNS}" link set lo up
ip netns exec "${NETNS}" \
sysctl -w net.ipv4.ip_local_port_range="32768 32768" \
> /dev/null 2>&1
ip netns exec "${NETNS}" \
sysctl -w net.ipv4.ip_autobind_reuse=1 > /dev/null 2>&1
}
cleanup() {
ip netns del "${NETNS}"
}
trap cleanup EXIT
setup
do_test() {
ip netns exec "${NETNS}" ./reuseaddr_ports_exhausted
}
do_test
echo "tests done"
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