From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org
Subject: [PATCH 05/24] devtmpfs: open code ksys_chdir and ksys_chroot
Date: Tue, 21 Jul 2020 18:27:59 +0200 [thread overview]
Message-ID: <20200721162818.197315-6-hch@lst.de> (raw)
In-Reply-To: <20200721162818.197315-1-hch@lst.de>
devtmpfs is the only non-early init caller of ksys_chdir and ksys_chroot
with kernel pointers. Just open code the two operations which only
really need a single path lookup anyway in devtmpfs_setup instead.
The open coded verson doesn't need any of the stale dentry revalidation
logic from the full blown version as those can't happen on tmpfs and
ramfs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/base/devtmpfs.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 5e8d677ee783bc..f798d3976b4052 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -25,6 +25,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kthread.h>
+#include <linux/fs_struct.h>
#include <uapi/linux/mount.h>
#include "base.h"
@@ -393,6 +394,7 @@ static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
static int devtmpfs_setup(void *p)
{
+ struct path path;
int err;
err = ksys_unshare(CLONE_NEWNS);
@@ -401,8 +403,16 @@ static int devtmpfs_setup(void *p)
err = devtmpfs_do_mount("/");
if (err)
goto out;
- ksys_chdir("/.."); /* will traverse into overmounted root */
- ksys_chroot(".");
+
+ /* traverse into overmounted root and then chroot to it */
+ if (!kern_path("/..", LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path) &&
+ !inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR) &&
+ ns_capable(current_user_ns(), CAP_SYS_CHROOT) &&
+ !security_path_chroot(&path)) {
+ set_fs_pwd(current->fs, &path);
+ set_fs_root(current->fs, &path);
+ }
+ path_put(&path);
out:
*(int *)p = err;
complete(&setup_done);
--
2.27.0
next prev parent reply other threads:[~2020-07-21 16:30 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 16:27 add file system helpers that take kernel pointers for the init code v2 Christoph Hellwig
2020-07-21 16:27 ` [PATCH 01/24] fs: refactor do_mount Christoph Hellwig
2020-07-21 16:27 ` [PATCH 02/24] fs: refactor ksys_umount Christoph Hellwig
2020-07-21 16:27 ` [PATCH 03/24] fs: push the getname from do_rmdir into the callers Christoph Hellwig
2020-07-21 16:27 ` [PATCH 04/24] devtmpfs: open code do_mount Christoph Hellwig
2020-07-21 16:27 ` Christoph Hellwig [this message]
2020-07-21 16:49 ` [PATCH 05/24] devtmpfs: open code ksys_chdir and ksys_chroot Linus Torvalds
2020-07-21 17:16 ` Al Viro
2020-07-21 18:26 ` Christoph Hellwig
2020-07-21 16:28 ` [PATCH 06/24] md: open code vfs_stat in md_setup_drive Christoph Hellwig
2020-07-21 16:55 ` Al Viro
2020-07-21 18:27 ` Christoph Hellwig
2020-07-22 7:44 ` Al Viro
2020-07-22 14:05 ` Christoph Hellwig
2020-07-21 16:28 ` [PATCH 07/24] init: initialize ramdisk_execute_command at compile time Christoph Hellwig
2020-07-21 16:28 ` [PATCH 08/24] init: move the prepare_namespace prototype to init/do_mounts.h Christoph Hellwig
2020-07-21 16:28 ` [PATCH 09/24] init: mark create_dev as __init Christoph Hellwig
2020-07-21 16:28 ` [PATCH 10/24] init: open code ksys_umount in handle_initrd Christoph Hellwig
2020-07-21 16:28 ` [PATCH 11/24] init: open code do_utimes in do_utime Christoph Hellwig
2020-07-21 16:28 ` [PATCH 12/24] init: add an init_mount helper Christoph Hellwig
2020-07-21 16:58 ` Al Viro
2020-07-21 16:28 ` [PATCH 13/24] init: add an init_unlink helper Christoph Hellwig
2020-07-21 17:12 ` Al Viro
2020-07-21 16:28 ` [PATCH 14/24] init: add an init_rmdir helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 15/24] init: add an init_chdir helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 16/24] init: add an init_chroot helper Christoph Hellwig
2020-07-21 17:10 ` Al Viro
2020-07-21 16:28 ` [PATCH 17/24] init: add an init_chown helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 18/24] init: add an init_chmod helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 19/24] init: add an init_eaccess helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 20/24] init: add an init_link helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 21/24] init: add an init_symlink helper Christoph Hellwig
2020-07-21 17:00 ` Al Viro
2020-07-21 16:28 ` [PATCH 22/24] init: add an init_mkdir helper Christoph Hellwig
2020-07-21 16:28 ` [PATCH 23/24] init: add an init_mknod helper Christoph Hellwig
2020-07-21 17:02 ` Al Viro
2020-07-21 16:28 ` [PATCH 24/24] init: add an init_lstat helper Christoph Hellwig
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