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From:   Matthieu Baerts <matthieu.baerts@tessares.net>
Date:   Thu, 08 Jun 2023 18:38:51 +0200
Subject: [PATCH net 09/14] selftests: mptcp: sockopt: relax expected
 returned size
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Message-Id: <20230608-upstream-net-20230608-mptcp-selftests-support-old-kernels-part-2-v1-9-20997a6fd841@tessares.net>
References: <20230608-upstream-net-20230608-mptcp-selftests-support-old-kernels-part-2-v1-0-20997a6fd841@tessares.net>
In-Reply-To: <20230608-upstream-net-20230608-mptcp-selftests-support-old-kernels-part-2-v1-0-20997a6fd841@tessares.net>
To:     mptcp@lists.linux.dev, Mat Martineau <martineau@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Shuah Khan <shuah@kernel.org>,
        Davide Caratti <dcaratti@redhat.com>,
        Dmytro Shytyi <dmytro@shytyi.net>,
        Menglong Dong <imagedong@tencent.com>,
        Geliang Tang <geliang.tang@suse.com>,
        Kishen Maloor <kishen.maloor@intel.com>
Cc:     Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
        Matthieu Baerts <matthieu.baerts@tessares.net>,
        stable@vger.kernel.org
Precedence: bulk

Selftests are supposed to run on any kernels, including the old ones not
supporting all MPTCP features.

One of them is the getsockopt(SOL_MPTCP) to get info about the MPTCP
connections introduced by commit 55c42fa7fa33 ("mptcp: add MPTCP_INFO
getsockopt") and the following ones.

We cannot guess in advance which sizes the kernel will returned: older
kernel can returned smaller sizes, e.g. recently the tcp_info structure
has been modified in commit 71fc704768f6 ("tcp: add rcv_wnd and
plb_rehash to TCP_INFO") where a new field has been added.

The userspace can also expect a smaller size if it is compiled with old
uAPI kernel headers.

So for these sizes, we can only check if they are above a certain
threshold, 0 for the moment. We can also only compared sizes with the
ones set by the kernel.

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/368
Fixes: ce9979129a0b ("selftests: mptcp: add mptcp getsockopt test cases")
Cc: stable@vger.kernel.org
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
 tools/testing/selftests/net/mptcp/mptcp_sockopt.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
index ae61f39556ca..b35148edbf02 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
@@ -87,6 +87,10 @@ struct so_state {
 	uint64_t tcpi_rcv_delta;
 };
 
+#ifndef MIN
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
 static void die_perror(const char *msg)
 {
 	perror(msg);
@@ -349,13 +353,14 @@ static void do_getsockopt_tcp_info(struct so_state *s, int fd, size_t r, size_t
 			xerror("getsockopt MPTCP_TCPINFO (tries %d, %m)");
 
 		assert(olen <= sizeof(ti));
-		assert(ti.d.size_user == ti.d.size_kernel);
-		assert(ti.d.size_user == sizeof(struct tcp_info));
+		assert(ti.d.size_kernel > 0);
+		assert(ti.d.size_user ==
+		       MIN(ti.d.size_kernel, sizeof(struct tcp_info)));
 		assert(ti.d.num_subflows == 1);
 
 		assert(olen > (socklen_t)sizeof(struct mptcp_subflow_data));
 		olen -= sizeof(struct mptcp_subflow_data);
-		assert(olen == sizeof(struct tcp_info));
+		assert(olen == ti.d.size_user);
 
 		if (ti.ti[0].tcpi_bytes_sent == w &&
 		    ti.ti[0].tcpi_bytes_received == r)
@@ -401,13 +406,14 @@ static void do_getsockopt_subflow_addrs(int fd)
 		die_perror("getsockopt MPTCP_SUBFLOW_ADDRS");
 
 	assert(olen <= sizeof(addrs));
-	assert(addrs.d.size_user == addrs.d.size_kernel);
-	assert(addrs.d.size_user == sizeof(struct mptcp_subflow_addrs));
+	assert(addrs.d.size_kernel > 0);
+	assert(addrs.d.size_user ==
+	       MIN(addrs.d.size_kernel, sizeof(struct mptcp_subflow_addrs)));
 	assert(addrs.d.num_subflows == 1);
 
 	assert(olen > (socklen_t)sizeof(struct mptcp_subflow_data));
 	olen -= sizeof(struct mptcp_subflow_data);
-	assert(olen == sizeof(struct mptcp_subflow_addrs));
+	assert(olen == addrs.d.size_user);
 
 	llen = sizeof(local);
 	ret = getsockname(fd, (struct sockaddr *)&local, &llen);

-- 
2.40.1