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selftests/net: Repair RST passive reset selftest

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Currently, the test is racy and seems to not pass anymore.

In order to rectify it, aim on TCP_TW_RST.
Doesn't seem way too good with this sleep() part, but it seems as
a reasonable compromise for the test. There is a plan in-line comment on
how-to improve it, going to do it on the top, at this moment I want it
to run on netdev/patchwork selftests dashboard.

It also slightly changes tcp_ao-lib in order to get SO_ERROR propagated
to test_client_verify() return value.

Fixes: c6df7b2361 ("selftests/net: Add TCP-AO RST test")
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20240130-tcp-ao-test-key-mgmt-v2-3-d190430a6c60@arista.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Dmitry Safonov 2024-01-30 03:51:54 +00:00 committed by Jakub Kicinski
parent 384aa16d37
commit 6caf3adcc8
2 changed files with 98 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
tools/testing/selftests/net/tcp_ao/lib/sock.c
View File

@ -62,7 +62,9 @@ int test_wait_fd(int sk, time_t sec, bool write)
return -ETIMEDOUT;
}
if (getsockopt(sk, SOL_SOCKET, SO_ERROR, &ret, &slen) || ret)
if (getsockopt(sk, SOL_SOCKET, SO_ERROR, &ret, &slen))
return -errno;
if (ret)
return -ret;
return 0;
}
@ -584,9 +586,11 @@ int test_client_verify(int sk, const size_t msg_len, const size_t nr,
{
size_t buf_sz = msg_len * nr;
char *buf = alloca(buf_sz);
ssize_t ret;
randomize_buffer(buf, buf_sz);
if (test_client_loop(sk, buf, buf_sz, msg_len, timeout_sec) != buf_sz)
return -1;
return 0;
ret = test_client_loop(sk, buf, buf_sz, msg_len, timeout_sec);
if (ret < 0)
return (int)ret;
return ret != buf_sz ? -1 : 0;
}

138
tools/testing/selftests/net/tcp_ao/rst.c
View File

@ -1,10 +1,33 @@
// SPDX-License-Identifier: GPL-2.0
/* Author: Dmitry Safonov <dima@arista.com> */
/*
* The test checks that both active and passive reset have correct TCP-AO
* signature. An "active" reset (abort) here is procured from closing
* listen() socket with non-accepted connections in the queue:
* inet_csk_listen_stop() => inet_child_forget() =>
* => tcp_disconnect() => tcp_send_active_reset()
*
* The passive reset is quite hard to get on established TCP connections.
* It could be procured from non-established states, but the synchronization
* part from userspace in order to reliably get RST seems uneasy.
* So, instead it's procured by corrupting SEQ number on TIMED-WAIT state.
*
* It's important to test both passive and active RST as they go through
* different code-paths:
* - tcp_send_active_reset() makes no-data skb, sends it with tcp_transmit_skb()
* - tcp_v*_send_reset() create their reply skbs and send them with
* ip_send_unicast_reply()
*
* In both cases TCP-AO signatures have to be correct, which is verified by
* (1) checking that the TCP-AO connection was reset and (2) TCP-AO counters.
*
* Author: Dmitry Safonov <dima@arista.com>
*/
#include <inttypes.h>
#include "../../../../include/linux/kernel.h"
#include "aolib.h"
const size_t quota = 1000;
const size_t packet_sz = 100;
/*
* Backlog == 0 means 1 connection in queue, see:
* commit 64a146513f8f ("[NET]: Revert incorrect accept queue...")
@ -59,26 +82,6 @@ static void close_forced(int sk)
close(sk);
}
static int test_wait_for_exception(int sk, time_t sec)
{
struct timeval tv = { .tv_sec = sec };
struct timeval *ptv = NULL;
fd_set efds;
int ret;
FD_ZERO(&efds);
FD_SET(sk, &efds);
if (sec)
ptv = &tv;
errno = 0;
ret = select(sk + 1, NULL, NULL, &efds, ptv);
if (ret < 0)
return -errno;
return ret ? sk : 0;
}
static void test_server_active_rst(unsigned int port)
{
struct tcp_ao_counters cnt1, cnt2;
@ -155,17 +158,16 @@ static void test_server_passive_rst(unsigned int port)
test_fail("server returned %zd", bytes);
}
synchronize_threads(); /* 3: chekpoint/restore the connection */
synchronize_threads(); /* 3: checkpoint the client */
synchronize_threads(); /* 4: close the server, creating twsk */
if (test_get_tcp_ao_counters(sk, &ao2))
test_error("test_get_tcp_ao_counters()");
synchronize_threads(); /* 4: terminate server + send more on client */
bytes = test_server_run(sk, quota, TEST_RETRANSMIT_SEC);
close(sk);
synchronize_threads(); /* 5: restore the socket, send more data */
test_tcp_ao_counters_cmp("passive RST server", &ao1, &ao2, TEST_CNT_GOOD);
synchronize_threads(); /* 5: verified => closed */
close(sk);
synchronize_threads(); /* 6: server exits */
}
static void *server_fn(void *arg)
@ -284,7 +286,7 @@ static void test_client_active_rst(unsigned int port)
test_error("test_wait_fds(): %d", err);
synchronize_threads(); /* 3: close listen socket */
if (test_client_verify(sk[0], 100, quota / 100, TEST_TIMEOUT_SEC))
if (test_client_verify(sk[0], packet_sz, quota / packet_sz, TEST_TIMEOUT_SEC))
test_fail("Failed to send data on connected socket");
else
test_ok("Verified established tcp connection");
@ -323,7 +325,6 @@ static void test_client_passive_rst(unsigned int port)
struct tcp_sock_state img;
sockaddr_af saddr;
int sk, err;
socklen_t slen = sizeof(err);
sk = socket(test_family, SOCK_STREAM, IPPROTO_TCP);
if (sk < 0)
@ -337,18 +338,51 @@ static void test_client_passive_rst(unsigned int port)
test_error("failed to connect()");
synchronize_threads(); /* 2: accepted => send data */
if (test_client_verify(sk, 100, quota / 100, TEST_TIMEOUT_SEC))
if (test_client_verify(sk, packet_sz, quota / packet_sz, TEST_TIMEOUT_SEC))
test_fail("Failed to send data on connected socket");
else
test_ok("Verified established tcp connection");
synchronize_threads(); /* 3: chekpoint/restore the connection */
synchronize_threads(); /* 3: checkpoint the client */
test_enable_repair(sk);
test_sock_checkpoint(sk, &img, &saddr);
test_ao_checkpoint(sk, &ao_img);
test_kill_sk(sk);
test_disable_repair(sk);
img.out.seq += quota;
synchronize_threads(); /* 4: close the server, creating twsk */
/*
* The "corruption" in SEQ has to be small enough to fit into TCP
* window, see tcp_timewait_state_process() for out-of-window
* segments.
*/
img.out.seq += 5; /* 5 is more noticeable in tcpdump than 1 */
/*
* FIXME: This is kind-of ugly and dirty, but it works.
*
* At this moment, the server has close'ed(sk).
* The passive RST that is being targeted here is new data after
* half-duplex close, see tcp_timewait_state_process() => TCP_TW_RST
*
* What is needed here is:
* (1) wait for FIN from the server
* (2) make sure that the ACK from the client went out
* (3) make sure that the ACK was received and processed by the server
*
* Otherwise, the data that will be sent from "repaired" socket
* post SEQ corruption may get to the server before it's in
* TCP_FIN_WAIT2.
*
* (1) is easy with select()/poll()
* (2) is possible by polling tcpi_state from TCP_INFO
* (3) is quite complex: as server's socket was already closed,
* probably the way to do it would be tcp-diag.
*/
sleep(TEST_RETRANSMIT_SEC);
synchronize_threads(); /* 5: restore the socket, send more data */
test_kill_sk(sk);
sk = socket(test_family, SOCK_STREAM, IPPROTO_TCP);
if (sk < 0)
@ -366,25 +400,33 @@ static void test_client_passive_rst(unsigned int port)
test_disable_repair(sk);
test_sock_state_free(&img);
synchronize_threads(); /* 4: terminate server + send more on client */
if (test_client_verify(sk, 100, quota / 100, 2 * TEST_TIMEOUT_SEC))
test_ok("client connection broken post-seq-adjust");
/*
* This is how "passive reset" is acquired in this test from TCP_TW_RST:
*
* IP 10.0.254.1.7011 > 10.0.1.1.59772: Flags [P.], seq 901:1001, ack 1001, win 249,
* options [tcp-ao keyid 100 rnextkeyid 100 mac 0x10217d6c36a22379086ef3b1], length 100
* IP 10.0.254.1.7011 > 10.0.1.1.59772: Flags [F.], seq 1001, ack 1001, win 249,
* options [tcp-ao keyid 100 rnextkeyid 100 mac 0x104ffc99b98c10a5298cc268], length 0
* IP 10.0.1.1.59772 > 10.0.254.1.7011: Flags [.], ack 1002, win 251,
* options [tcp-ao keyid 100 rnextkeyid 100 mac 0xe496dd4f7f5a8a66873c6f93,nop,nop,sack 1 {1001:1002}], length 0
* IP 10.0.1.1.59772 > 10.0.254.1.7011: Flags [P.], seq 1006:1106, ack 1001, win 251,
* options [tcp-ao keyid 100 rnextkeyid 100 mac 0x1b5f3330fb23fbcd0c77d0ca], length 100
* IP 10.0.254.1.7011 > 10.0.1.1.59772: Flags [R], seq 3215596252, win 0,
* options [tcp-ao keyid 100 rnextkeyid 100 mac 0x0bcfbbf497bce844312304b2], length 0
*/
err = test_client_verify(sk, packet_sz, quota / packet_sz, 2 * TEST_TIMEOUT_SEC);
/* Make sure that the connection was reset, not timeouted */
if (err && err == -ECONNRESET)
test_ok("client sock was passively reset post-seq-adjust");
else if (err)
test_fail("client sock was not reset post-seq-adjust: %d", err);
else
test_fail("client connection still works post-seq-adjust");
test_wait_for_exception(sk, TEST_TIMEOUT_SEC);
if (getsockopt(sk, SOL_SOCKET, SO_ERROR, &err, &slen))
test_error("getsockopt()");
if (err != ECONNRESET && err != EPIPE)
test_fail("client connection was not reset: %d", err);
else
test_ok("client connection was reset");
test_fail("client sock is yet connected post-seq-adjust");
if (test_get_tcp_ao_counters(sk, &ao2))
test_error("test_get_tcp_ao_counters()");
synchronize_threads(); /* 5: verified => closed */
synchronize_threads(); /* 6: server exits */
close(sk);
test_tcp_ao_counters_cmp("client passive RST", &ao1, &ao2, TEST_CNT_GOOD);
}
@ -410,6 +452,6 @@ static void *client_fn(void *arg)
int main(int argc, char *argv[])
{
test_init(15, server_fn, client_fn);
test_init(14, server_fn, client_fn);
return 0;
}