From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from picard.linux.it (picard.linux.it [213.254.12.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3E06AC5DF81 for ; Thu, 20 Aug 2026 07:47:25 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 818F63CE107 for ; Thu, 20 Aug 2026 09:47:23 +0200 (CEST) Received: from in-7.smtp.seeweb.it (in-7.smtp.seeweb.it [217.194.8.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1) server-digest SHA384) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id BCA753CE356 for ; Thu, 20 Aug 2026 09:45:02 +0200 (CEST) Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-7.smtp.seeweb.it (Postfix) with ESMTPS id C412C200250 for ; Thu, 20 Aug 2026 09:45:01 +0200 (CEST) Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 26E653EF2; Thu, 20 Aug 2026 07:44:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1787211897; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ChS46TFZYG6EIzGsCmOEJz0Ti3RK28G4/m5aHgUK8eQ=; b=nNvQNAQ8lsA9SP8c6EqaR/mXLik8ATawnUupdhZXZWtgIiyqHXo4t0Y6dDgnaSkltgZtFB rpKojCfeEah0cL7pTfHZM2gK9/AxeU152jBstnSPQ8oOBdbaABzuixiSTnYorLEPyxZwQr bYKWQJX1yoOOxyY6FHT06IT7VHRQCD8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1787211897; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ChS46TFZYG6EIzGsCmOEJz0Ti3RK28G4/m5aHgUK8eQ=; b=neHHC+C3s52DeZRV5tVzcYZK3iQJvHwFOyuDdrYm88s2Cq3sF8c5/CGB3/uNtX4qb8ra4F R3w9AwgnaTPdE8Bg== Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=IFFGYIlv; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=b+ayt+Xd DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1787211893; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ChS46TFZYG6EIzGsCmOEJz0Ti3RK28G4/m5aHgUK8eQ=; b=IFFGYIlvZ+8DUeORR9ix9hDzTZTKa1T420cRGMMuiZBJc+YUJEpkVjTJqxR7GnK0JFAuHg 3MRNJ2L8Htb17csYjYiKHgHnq2lIkJIZw5noLwS5lPagYhDsI8RuUPfYUWhjFDr+xG+Ijq J9wPvEZ5Ag1wE2PvZcPEhvjDekN2vhM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1787211893; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ChS46TFZYG6EIzGsCmOEJz0Ti3RK28G4/m5aHgUK8eQ=; b=b+ayt+XdZ+Ce9sQpkacGTy//1mbGP2t2ku12T3kI4muaf7oaCufqJ2eGgIc3JvuQkfJXfC YyzzL+muWtTcvOCg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id D8C6C3684; Thu, 20 Aug 2026 07:44:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id sBLUMW6whmr3YgAAD6G6ig (envelope-from ); Thu, 20 Aug 2026 07:44:46 +0000 From: Andrea Cervesato Date: Thu, 20 Aug 2026 09:44:52 +0200 MIME-Version: 1.0 Message-Id: <20260820-fchroot-v2-12-062ed20957a0@suse.com> References: <20260820-fchroot-v2-0-062ed20957a0@suse.com> In-Reply-To: <20260820-fchroot-v2-0-062ed20957a0@suse.com> To: Linux Test Project X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1787211883; l=3691; i=andrea.cervesato@suse.com; s=20251210; h=from:subject:message-id; bh=IfBpVCYc+BUTq916ryWmd/eYSrixxLxDKWAeVldtrGo=; b=syw/cM6CO2LWtHyajTvGV8OzOKteo4g48y/OiJJ2slct5XFHNU9ePHpZa0wc4D4p0epESDQiz YMiwC7anh4rDoWCiqmo0PhJGcXw6V9yS2SWJ85cBVplDo4uzkQwDgls X-Developer-Key: i=andrea.cervesato@suse.com; a=ed25519; pk=zKY+6GCauOiuHNZ//d8PQ/UL4jFCTKbXrzXAOQSLevI= X-Rspamd-Action: no action X-Rspamd-Queue-Id: 26E653EF2 X-Spamd-Result: default: False [-5.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; DWL_DNSWL_LOW(-1.00)[suse.de:dkim]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,suse.com:mid,suse.de:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Virus-Scanned: clamav-milter 1.0.9 at in-7.smtp.seeweb.it X-Virus-Status: Clean Subject: [LTP] [PATCH STAGING v2 12/16] fchroot09: test setns escape from failfs root X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" From: Andrea Cervesato Verify that entering failfs with fchroot() is hard to undo: a process inside counts as chrooted, so the remaining way out is a pre-opened mount namespace fd. setns() into it resets both the root and the working directory. Signed-off-by: Andrea Cervesato --- runtest/staging | 1 + testcases/kernel/syscalls/fchroot/.gitignore | 1 + testcases/kernel/syscalls/fchroot/fchroot09.c | 87 +++++++++++++++++++++++++++ 3 files changed, 89 insertions(+) diff --git a/runtest/staging b/runtest/staging index 8dfe95c4a..23f6c6a20 100644 --- a/runtest/staging +++ b/runtest/staging @@ -8,3 +8,4 @@ fchroot05 fchroot05 fchroot06 fchroot06 fchroot07 fchroot07 fchroot08 fchroot08 +fchroot09 fchroot09 diff --git a/testcases/kernel/syscalls/fchroot/.gitignore b/testcases/kernel/syscalls/fchroot/.gitignore index c099b4b3a..e803fa2b7 100644 --- a/testcases/kernel/syscalls/fchroot/.gitignore +++ b/testcases/kernel/syscalls/fchroot/.gitignore @@ -6,3 +6,4 @@ fchroot05 fchroot06 fchroot07 fchroot08 +fchroot09 diff --git a/testcases/kernel/syscalls/fchroot/fchroot09.c b/testcases/kernel/syscalls/fchroot/fchroot09.c new file mode 100644 index 000000000..adcc47352 --- /dev/null +++ b/testcases/kernel/syscalls/fchroot/fchroot09.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2026 SUSE LLC Andrea Cervesato + */ + +/*\ + * Test that :manpage:`setns(2)` escapes the failfs root. + * + * Entering failfs with :manpage:`fchroot(2)` is hard to undo: a process + * inside counts as chrooted, so :manpage:`chroot(2)` and fchroot() back + * out require ``CAP_SYS_CHROOT``. The remaining way out is a pre-opened mount + * namespace file descriptor: setns() into it resets both the root and the + * working directory. + * + * Root is required because entering failfs requires ``CAP_SYS_CHROOT`` and + * :manpage:`setns(2)` into the mount namespace requires ``CAP_SYS_ADMIN``. + * + * The test runs in a forked child so the root of the parent process is + * left untouched. + */ + +#define _GNU_SOURCE +#include +#include +#include "tst_test.h" +#include "lapi/fcntl.h" +#include "lapi/sched.h" +#include "lapi/setns.h" +#include "lapi/syscalls.h" + +#define ABSDIR "abs" + +static void run(void) +{ + if (SAFE_FORK()) + return; + + struct stat realroot, realcwd, st; + int nsfd; + + SAFE_STAT("/", &realroot); + SAFE_STAT(".", &realcwd); + nsfd = SAFE_OPEN("/proc/self/ns/mnt", O_RDONLY); + + TST_EXP_PASS(tst_syscall(__NR_fchroot, FD_FAILFS_ROOT, 0), + "fchroot() with the FD_FAILFS_ROOT sentinel"); + + TST_EXP_FAIL2(open(ABSDIR, O_PATH), EOPNOTSUPP, + "absolute lookup after entering failfs"); + + TST_EXP_PASS(setns(nsfd, CLONE_NEWNS), + "setns() back into the mount namespace"); + + SAFE_CLOSE(nsfd); + + SAFE_STAT("/", &st); + TST_EXP_EXPR(st.st_dev == realroot.st_dev && + st.st_ino == realroot.st_ino, + "root restored after setns()"); + + SAFE_STAT(tst_tmpdir_path(), &st); + TST_EXP_EXPR(st.st_dev == realcwd.st_dev && + st.st_ino == realcwd.st_ino, + "working directory restored after setns()"); + + exit(0); +} + +static void setup(void) +{ + char *tmpdir; + char abs_path[PATH_MAX]; + + tmpdir = tst_tmpdir_path(); + snprintf(abs_path, sizeof(abs_path), "%s/%s", tmpdir, "target"); + + SAFE_TOUCH("target", 0644, NULL); + SAFE_SYMLINK(abs_path, ABSDIR); +} + +static struct tst_test test = { + .test_all = run, + .setup = setup, + .needs_root = 1, + .forks_child = 1, + .needs_tmpdir = 1, +}; -- 2.51.0 -- Mailing list info: https://lists.linux.it/listinfo/ltp