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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9134EC433ED for ; Tue, 21 Jul 2020 16:28:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69C6A22482 for ; Tue, 21 Jul 2020 16:28:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ST3g9v0B" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730450AbgGUQ2w (ORCPT ); Tue, 21 Jul 2020 12:28:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730023AbgGUQ2u (ORCPT ); Tue, 21 Jul 2020 12:28:50 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 481ADC061794; Tue, 21 Jul 2020 09:28:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=rLxcfdL2zVDL0b0Nzk8JqYM0sd8pftMXzm0dy6UrVug=; b=ST3g9v0BuSSi2OKz/gs7aY7Dxb 43xy05rogt18zI8To1tLR665ayv7kEMPeLc6YUUZcvU/el8DRoF2UMDwNopsOFdRRiiOzWkgsU9Be /+dYT2rtimbVJKy+pGdXoF7bNRxnWQcqapd7hhkSQ6rv4ZFQ62qkAukYQKKCVs59OwA+iX+ErbRv7 Vo6W09Ad+GiKMMwk4YLwFC6YRibdviRURmSqQkG9B9ltfDjMSlt6MaT664xxzlm83Y/U/coqrmiCe /dR+tWeXV7XpBkgSIIo/aMsAPbhuppEq0ekULlCh29JhK8sfIpDWfAiNXjcF/yBqGA9+MRZHuwvFz Eez4HGXQ==; Received: from [2001:4bb8:18c:2acc:5b1c:6483:bd6d:e406] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jxv8H-0007VI-2Y; Tue, 21 Jul 2020 16:28:45 +0000 From: Christoph Hellwig To: Al Viro , Linus Torvalds Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH 16/24] init: add an init_chroot helper Date: Tue, 21 Jul 2020 18:28:10 +0200 Message-Id: <20200721162818.197315-17-hch@lst.de> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200721162818.197315-1-hch@lst.de> References: <20200721162818.197315-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Add a simple helper to chroot with a kernel space file name and switch the early init code over to it. Remove the now unused ksys_chroot. Signed-off-by: Christoph Hellwig --- fs/open.c | 7 +------ include/linux/syscalls.h | 2 -- init/do_mounts.c | 2 +- init/do_mounts.h | 1 + init/do_mounts_initrd.c | 4 ++-- init/fs.c | 23 +++++++++++++++++++++++ 6 files changed, 28 insertions(+), 11 deletions(-) diff --git a/fs/open.c b/fs/open.c index 723e0ac898935e..f62f4752bb436d 100644 --- a/fs/open.c +++ b/fs/open.c @@ -530,7 +530,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd) return error; } -int ksys_chroot(const char __user *filename) +SYSCALL_DEFINE1(chroot, const char __user *, filename) { struct path path; int error; @@ -563,11 +563,6 @@ int ksys_chroot(const char __user *filename) return error; } -SYSCALL_DEFINE1(chroot, const char __user *, filename) -{ - return ksys_chroot(filename); -} - static int chmod_common(const struct path *path, umode_t mode) { struct inode *inode = path->dentry->d_inode; diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 31fa67fb9894b3..e89d62e944dc0e 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1235,8 +1235,6 @@ asmlinkage long sys_ni_syscall(void); * Instead, use one of the functions which work equivalently, such as * the ksys_xyzyyz() functions prototyped below. */ - -int ksys_chroot(const char __user *filename); ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count); int ksys_fchown(unsigned int fd, uid_t user, gid_t group); ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count); diff --git a/init/do_mounts.c b/init/do_mounts.c index cc08ed7b44e764..c8ccdc80ffcdd5 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -629,7 +629,7 @@ void __init prepare_namespace(void) out: devtmpfs_mount(); init_mount(".", "/", NULL, MS_MOVE, NULL); - ksys_chroot("."); + init_chroot("."); } static bool is_tmpfs; diff --git a/init/do_mounts.h b/init/do_mounts.h index c82fcb27575877..810b37ce1db882 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -12,6 +12,7 @@ int __init init_mount(const char *dev_name, const char *dir_name, const char *type_page, unsigned long flags, void *data_page); int __init init_chdir(const char *filename); +int __init init_chroot(const char *filename); int __init init_unlink(const char *pathname); int __init init_rmdir(const char *pathname); diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index ef214a78e7ee49..697d45e4aa8c87 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -64,7 +64,7 @@ static int __init init_linuxrc(struct subprocess_info *info, struct cred *new) /* move initrd over / and chdir/chroot in initrd root */ init_chdir("/root"); init_mount(".", "/", NULL, MS_MOVE, NULL); - ksys_chroot("."); + init_chroot("."); ksys_setsid(); return 0; } @@ -102,7 +102,7 @@ static void __init handle_initrd(void) /* move initrd to rootfs' /old */ init_mount("..", ".", NULL, MS_MOVE, NULL); /* switch root and cwd back to / of rootfs */ - ksys_chroot(".."); + init_chroot(".."); if (new_decode_dev(real_root_dev) == Root_RAM0) { init_chdir("/old"); diff --git a/init/fs.c b/init/fs.c index f3d8da00662572..af55e6d40357dc 100644 --- a/init/fs.c +++ b/init/fs.c @@ -36,6 +36,29 @@ int __init init_chdir(const char *filename) return error; } +int __init init_chroot(const char *filename) +{ + struct path path; + int error; + + error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path); + if (error) + return error; + error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); + if (error) + goto dput_and_out; + error = -EPERM; + if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT)) + goto dput_and_out; + error = security_path_chroot(&path); + if (error) + goto dput_and_out; + set_fs_root(current->fs, &path); +dput_and_out: + path_put(&path); + return error; +} + int __init init_unlink(const char *pathname) { return do_unlinkat(AT_FDCWD, getname_kernel(pathname)); -- 2.27.0