From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 38A04333456; Tue, 21 Oct 2025 11:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761047142; cv=none; b=h8rwezb8ncwFDVOu+z6MqjMeG6LCbgyz98fSMqTi54IZHZWbWxCTRHkjX3BKGmyA17hgdstr78ktprUJ9EHkTkzv5syKsO6Td9KQWK3D1rZe512NYgRSzwtF8vj82zAzBrPcBYgXM5BWHQ/jJrK41AFhXCnd4/bVG27Q+fqx2Mk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761047142; c=relaxed/simple; bh=RDvCp753eytqBU6RSu1QM6e320xY8EyidsVLpCI0zLo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=UhA4zotpcu4o3GLWcTvWFHoZvhd8l3jdu7jvhDcimBYcHv/m4SoI7lmff0Af+y6UgOU6fNnYaiRlkhGNEJegEeRV02Z0fNTcB1SwuGBnjA7AaxB0JoYkNOklULWQJD57ED1Bmv7wyVOF5MeBwXRImqiWBGY4Hu3Pps/fA/sAlNA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O5BqrqdX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="O5BqrqdX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 411ABC4CEF1; Tue, 21 Oct 2025 11:45:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761047142; bh=RDvCp753eytqBU6RSu1QM6e320xY8EyidsVLpCI0zLo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=O5BqrqdXnTmUGJzOG5lohLFAXA4oN5CTfBe83OTWFxEvNFNaqgvy6agZsDoNDtKGB HQbNwaKZJ7MssB7MEwYoM6ZdS0h8PzWbBR1UUgc+wTxekM3K60IDmzPO3Hf3utdTK0 qvDH6vJMCJSgbVenWQEINAp5EUTxzYqBaUREp3pTCPXgEtYTkkW1ESATukXV2OoGt5 unNIjlky69JJBGN+b8Iyu1ndvRsGQZR6TvqRoO+uklZxNq9lf4y0YCfZNZWiUye+eu oIjIyTnMXnVYHUzy5a3ftavPAj+c+66MEC2n46682MT34AnfQAfvehjtMFf0p+AEOD hwP9kBFXHH8yA== From: Christian Brauner Date: Tue, 21 Oct 2025 13:43:27 +0200 Subject: [PATCH RFC DRAFT 21/50] selftests/namespaces: third active reference count tests Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251021-work-namespace-nstree-listns-v1-21-ad44261a8a5b@kernel.org> References: <20251021-work-namespace-nstree-listns-v1-0-ad44261a8a5b@kernel.org> In-Reply-To: <20251021-work-namespace-nstree-listns-v1-0-ad44261a8a5b@kernel.org> To: linux-fsdevel@vger.kernel.org, Josef Bacik , Jeff Layton Cc: Jann Horn , Mike Yuan , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , Lennart Poettering , Daan De Meyer , Aleksa Sarai , Amir Goldstein , Tejun Heo , Johannes Weiner , Thomas Gleixner , Alexander Viro , Jan Kara , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, Eric Dumazet , Jakub Kicinski , netdev@vger.kernel.org, Arnd Bergmann , Christian Brauner X-Mailer: b4 0.15-dev-96507 X-Developer-Signature: v=1; a=openpgp-sha256; l=3662; i=brauner@kernel.org; h=from:subject:message-id; bh=RDvCp753eytqBU6RSu1QM6e320xY8EyidsVLpCI0zLo=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWR8L3y7hHPfry/5lgY3mPptW09ZrXz+68E72X6j57r9L V1rvve+7ihlYRDjYpAVU2RxaDcJl1vOU7HZKFMDZg4rE8gQBi5OAZhInAIjw/50c4k/R6fIakXu Pcn2P9yZn3tS3wZmd/138nlNn04+Xsrwz140IOEl69cXtl9W9382yGy66yasfTNx9mHZxH9JVrN Z2QE= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Test that a namespace remains active while a process is using it, even after the creating process exits. Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 128 +++++++++++++++++++++ 1 file changed, 128 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index f628b4a4a927..63233f22517a 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -160,4 +160,132 @@ TEST(ns_inactive_after_exit) } } +/* + * Test that a namespace remains active while a process is using it, + * even after the creating process exits. + */ +TEST(ns_active_with_multiple_processes) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + int syncpipe[2]; + pid_t pid1, pid2; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + char sync_byte; + + /* Create pipes for communication */ + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(pipe(syncpipe), 0); + + pid1 = fork(); + ASSERT_GE(pid1, 0); + + if (pid1 == 0) { + /* First child - creates namespace */ + close(pipefd[0]); + close(syncpipe[1]); + + /* Create new network namespace */ + ret = unshare(CLONE_NEWNET); + if (ret < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + /* Open and get handle */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + /* Send handle to parent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + + /* Wait for signal before exiting */ + read(syncpipe[0], &sync_byte, 1); + close(syncpipe[0]); + exit(0); + } + + /* Parent reads handle */ + close(pipefd[1]); + ret = read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + ASSERT_GT(ret, 0); + + handle = (struct file_handle *)buf; + + /* Create second child that will keep namespace active */ + pid2 = fork(); + ASSERT_GE(pid2, 0); + + if (pid2 == 0) { + /* Second child - reopens the namespace */ + close(syncpipe[0]); + close(syncpipe[1]); + + /* Open the namespace via handle */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (fd < 0) { + exit(1); + } + + /* Join the namespace */ + ret = setns(fd, CLONE_NEWNET); + close(fd); + if (ret < 0) { + exit(1); + } + + /* Sleep to keep namespace active */ + sleep(1); + exit(0); + } + + /* Let second child enter the namespace */ + usleep(100000); /* 100ms */ + + /* Signal first child to exit */ + close(syncpipe[0]); + sync_byte = 'X'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + + /* Wait for first child */ + waitpid(pid1, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + + /* Namespace should still be active because second child is using it */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (fd < 0) { + /* If this fails, second child might not have entered namespace yet */ + TH_LOG("Warning: Could not reopen namespace (errno=%d)", errno); + } else { + close(fd); + } + + /* Wait for second child */ + waitpid(pid2, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); +} + TEST_HARNESS_MAIN -- 2.47.3