LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Dave Hansen <haveblue@us.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: hch@lst.de, viro@ZenIV.linux.org.uk, viro@ftp.linux.org.uk,
	miklos@szeredi.hu, Dave Hansen <haveblue@us.ibm.com>
Subject: [RFC][PATCH 13/30] r/o bind mounts: elevate write count for xattr_permission() callers
Date: Fri, 08 Feb 2008 14:27:04 -0800	[thread overview]
Message-ID: <20080208222704.28940418@kernel> (raw)
In-Reply-To: <20080208222641.6024A7CC@kernel>


This basically audits the callers of xattr_permission(), which calls
permission() and can perform writes to the filesystem.

Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 linux-2.6.git-dave/fs/nfsd/nfs4proc.c |    7 ++++++-
 linux-2.6.git-dave/fs/xattr.c         |   16 ++++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff -puN fs/nfsd/nfs4proc.c~r-o-bind-mounts-elevate-mount-count-for-extended-attributes fs/nfsd/nfs4proc.c
--- linux-2.6.git/fs/nfsd/nfs4proc.c~r-o-bind-mounts-elevate-mount-count-for-extended-attributes	2008-02-08 13:04:51.000000000 -0800
+++ linux-2.6.git-dave/fs/nfsd/nfs4proc.c	2008-02-08 13:04:51.000000000 -0800
@@ -658,14 +658,19 @@ nfsd4_setattr(struct svc_rqst *rqstp, st
 			return status;
 		}
 	}
+	status = mnt_want_write(cstate->current_fh.fh_export->ex_mnt);
+	if (status)
+		return status;
 	status = nfs_ok;
 	if (setattr->sa_acl != NULL)
 		status = nfsd4_set_nfs4_acl(rqstp, &cstate->current_fh,
 					    setattr->sa_acl);
 	if (status)
-		return status;
+		goto out;
 	status = nfsd_setattr(rqstp, &cstate->current_fh, &setattr->sa_iattr,
 				0, (time_t)0);
+out:
+	mnt_drop_write(cstate->current_fh.fh_export->ex_mnt);
 	return status;
 }
 
diff -puN fs/xattr.c~r-o-bind-mounts-elevate-mount-count-for-extended-attributes fs/xattr.c
--- linux-2.6.git/fs/xattr.c~r-o-bind-mounts-elevate-mount-count-for-extended-attributes	2008-02-08 13:04:51.000000000 -0800
+++ linux-2.6.git-dave/fs/xattr.c	2008-02-08 13:04:51.000000000 -0800
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/file.h>
 #include <linux/xattr.h>
+#include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
@@ -32,8 +33,6 @@ xattr_permission(struct inode *inode, co
 	 * filesystem  or on an immutable / append-only inode.
 	 */
 	if (mask & MAY_WRITE) {
-		if (IS_RDONLY(inode))
-			return -EROFS;
 		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 			return -EPERM;
 	}
@@ -262,7 +261,11 @@ sys_setxattr(char __user *path, char __u
 	error = user_path_walk(path, &nd);
 	if (error)
 		return error;
+	error = mnt_want_write(nd.mnt);
+	if (error)
+		return error;
 	error = setxattr(nd.dentry, name, value, size, flags);
+	mnt_drop_write(nd.mnt);
 	path_release(&nd);
 	return error;
 }
@@ -277,7 +280,11 @@ sys_lsetxattr(char __user *path, char __
 	error = user_path_walk_link(path, &nd);
 	if (error)
 		return error;
+	error = mnt_want_write(nd.mnt);
+	if (error)
+		return error;
 	error = setxattr(nd.dentry, name, value, size, flags);
+	mnt_drop_write(nd.mnt);
 	path_release(&nd);
 	return error;
 }
@@ -293,9 +300,14 @@ sys_fsetxattr(int fd, char __user *name,
 	f = fget(fd);
 	if (!f)
 		return error;
+	error = mnt_want_write(f->f_vfsmnt);
+	if (error)
+		goto out_fput;
 	dentry = f->f_path.dentry;
 	audit_inode(NULL, dentry);
 	error = setxattr(dentry, name, value, size, flags);
+	mnt_drop_write(f->f_vfsmnt);
+out_fput:
 	fput(f);
 	return error;
 }
_

  parent reply	other threads:[~2008-02-08 22:33 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-08 22:26 [RFC][PATCH 00/30] Read-only bind mounts (-mm resend) Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 01/30] reiserfs: eliminate private use of struct file in xattr Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 02/30] hppfs pass vfsmount to dentry_open() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 03/30] check for null vfsmount in dentry_open() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 04/30] fix up new filp allocators Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 05/30] do namei_flags calculation inside open_namei() Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 06/30] make open_namei() return a filp Dave Hansen
2008-02-09  5:09   ` Christoph Hellwig
2008-02-08 22:26 ` [RFC][PATCH 07/30] r/o bind mounts: stub functions Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 08/30] r/o bind mounts: create helper to drop file write access Dave Hansen
2008-02-08 22:26 ` [RFC][PATCH 09/30] r/o bind mounts: drop write during emergency remount Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 10/30] r/o bind mounts: elevate write count for vfs_rmdir() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 11/30] r/o bind mounts: elevate write count for callers of vfs_mkdir() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 12/30] r/o bind mounts: elevate mnt_writers for unlink callers Dave Hansen
2008-02-08 22:27 ` Dave Hansen [this message]
2008-02-08 22:27 ` [RFC][PATCH 14/30] r/o bind mounts: elevate write count for ncp_ioctl() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 15/30] r/o bind mounts: write counts for time functions Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 16/30] r/o bind mounts: elevate write count for do_utimes() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 17/30] r/o bind mounts: write count for file_update_time() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 18/30] r/o bind mounts: write counts for link/symlink Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 19/30] r/o bind mounts: elevate write count for ioctls() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 20/30] r/o bind mounts: elevate write count for open()s Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 21/30] r/o bind mounts: get write access for vfs_rename() callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 22/30] r/o bind mounts: elevate write count for chmod/chown callers Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 23/30] r/o bind mounts: write counts for truncate() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 24/30] r/o bind mounts: elevate count for xfs timestamp updates Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 25/30] r/o bind mounts: make access() use new r/o helper Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 26/30] r/o bind mounts: check mnt instead of superblock directly Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 27/30] r/o bind mounts: get callers of vfs_mknod/create() Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 28/30] r/o bind mounts: track numbers of writers to mounts Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 29/30] r/o bind mounts: honor mount writer counts at remount Dave Hansen
2008-02-08 22:27 ` [RFC][PATCH 30/30] r/o bind mounts: debugging for missed calls Dave Hansen
2008-02-09  6:39 ` [RFC][PATCH 00/30] Read-only bind mounts (-mm resend) Christoph Hellwig
2008-02-09  7:57 ` Al Viro
2008-02-12  5:06 ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20080208222704.28940418@kernel \
    --to=haveblue@us.ibm.com \
    --cc=hch@lst.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=miklos@szeredi.hu \
    --cc=viro@ZenIV.linux.org.uk \
    --cc=viro@ftp.linux.org.uk \
    --subject='Re: [RFC][PATCH 13/30] r/o bind mounts: elevate write count for xattr_permission() callers' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).