From patchwork Thu Aug 22 04:39:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13772654 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (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 434251CAA6 for ; Thu, 22 Aug 2024 04:39:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724301577; cv=none; b=snokEXg+b7eaA4+Ck2fqLZngpCGfyKh0wmQPQ3/eOI0U5mjwIxjsI+c5bxoYjMJyiRytNKc6tniUngRt1CatIG8PFxqR4E8estkgVxDEeHi/di3AZTneTnTsh5AIeUNrCbYwlVaD85qHSyQOT2bp1STjVkMKSXLWBeleYWzzC9w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724301577; c=relaxed/simple; bh=si1+5ckOBPzI1ghXUuFTsZOYlXHhTyB/XUwwp/ozvcI=; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=e9P2qDvqBDDT+4ooSBTRGhIsbJovrqhmrzTSMb67XdPVjD9ftQNcpazccY6PKgJPkqAIicM6SWTsHVhxeS+WyHCN9zQOrz1CUjwaatgq0M2Rw6tDocN6wpgi/PsKnh1riXmubwOUnJuILOAsYk9Cq1NeUYMPg/8ggk5eCH11Sgo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=R0YXP83E; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="R0YXP83E" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:Content-Type:MIME-Version: Message-ID:Subject:To:From:Date:Reply-To:Cc:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To:References; bh=AA4WaTEkNjbjrZGfNu4KV2H8PXXj+NYazaOW4bROYjE=; b=R0YXP83Ems8aowdPQLXqMLRTEr UMg28z+t/0ETQKuqxL8mNjw9KyQLxq2PH3M7MQtRJ1lXWGsTD0qGFi6Ru2FNHNFZwz505w4925L33 /VDw2NTIup6D+mbmt8Ot482GSUdW86XLKUn9vKTYVtFfJv6p0J1y+h2Vi1GdkRanZwrXo8H6miWoZ TT7mRW8a7eaVptD34V8BBhIYRrjoJ5VXepW8dYdK+hlU5KwOAlP8ttYWVy+e65oqcRN/bb209hoFp LobdO8fZsri+6bnlBQ+pL5Kbt4K9d32OYtoH+7IrIimaxX+T2/5ZiingxDiA2pDnWNR9+7O+4FcId 7X1yDzfg==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.98 #2 (Red Hat Linux)) id 1sgzbg-00000003z5d-32D3 for linux-kselftest@vger.kernel.org; Thu, 22 Aug 2024 04:39:32 +0000 Date: Thu, 22 Aug 2024 05:39:32 +0100 From: Al Viro To: linux-kselftest@vger.kernel.org Subject: [PATCH] test coverage for dup_fd() failure handling in unshare_fd() Message-ID: <20240822043932.GT504335@ZenIV> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Sender: Al Viro At some point there'd been a dumb braino during the dup_fd() calling conventions change; caught by smatch and immediately fixed. The trouble is, there had been no test coverage for the dup_fd() failure handling - neither in kselftests nor in LTP. Fortunately, it can be triggered on stock kernel - ENOMEM would require fault injection, but EMFILE can be had with sysctl alone (fs.nr_open). Signed-off-by: Al Viro --- diff --git a/tools/testing/selftests/core/Makefile b/tools/testing/selftests/core/Makefile index ce262d097269..8e99f87f5d7c 100644 --- a/tools/testing/selftests/core/Makefile +++ b/tools/testing/selftests/core/Makefile @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only CFLAGS += -g $(KHDR_INCLUDES) -TEST_GEN_PROGS := close_range_test +TEST_GEN_PROGS := close_range_test unshare_test include ../lib.mk diff --git a/tools/testing/selftests/core/unshare_test.c b/tools/testing/selftests/core/unshare_test.c new file mode 100644 index 000000000000..7fec9dfb1b0e --- /dev/null +++ b/tools/testing/selftests/core/unshare_test.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../kselftest_harness.h" +#include "../clone3/clone3_selftests.h" + +TEST(unshare_EMFILE) +{ + pid_t pid; + int status; + struct __clone_args args = { + .flags = CLONE_FILES, + .exit_signal = SIGCHLD, + }; + int fd; + ssize_t n, n2; + static char buf[512], buf2[512]; + struct rlimit rlimit; + int nr_open; + + fd = open("/proc/sys/fs/nr_open", O_RDWR); + ASSERT_GE(fd, 0); + + n = read(fd, buf, sizeof(buf)); + ASSERT_GT(n, 0); + ASSERT_EQ(buf[n - 1], '\n'); + + ASSERT_EQ(sscanf(buf, "%d", &nr_open), 1); + + ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlimit)); + + /* bump fs.nr_open */ + n2 = sprintf(buf2, "%d\n", nr_open + 1024); + lseek(fd, 0, SEEK_SET); + write(fd, buf2, n2); + + /* bump ulimit -n */ + rlimit.rlim_cur = nr_open + 1024; + rlimit.rlim_max = nr_open + 1024; + EXPECT_EQ(0, setrlimit(RLIMIT_NOFILE, &rlimit)) { + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + exit(EXIT_FAILURE); + } + + /* get a descriptor past the old fs.nr_open */ + EXPECT_GE(dup2(2, nr_open + 64), 0) { + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + exit(EXIT_FAILURE); + } + + /* get descriptor table shared */ + pid = sys_clone3(&args, sizeof(args)); + EXPECT_GE(pid, 0) { + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + exit(EXIT_FAILURE); + } + + if (pid == 0) { + int err; + + /* restore fs.nr_open */ + lseek(fd, 0, SEEK_SET); + write(fd, buf, n); + /* ... and now unshare(CLONE_FILES) must fail with EMFILE */ + err = unshare(CLONE_FILES); + EXPECT_EQ(err, -1) + exit(EXIT_FAILURE); + EXPECT_EQ(errno, EMFILE) + exit(EXIT_FAILURE); + exit(EXIT_SUCCESS); + } + + EXPECT_EQ(waitpid(pid, &status, 0), pid); + EXPECT_EQ(true, WIFEXITED(status)); + EXPECT_EQ(0, WEXITSTATUS(status)); +} + +TEST_HARNESS_MAIN