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Message-Id: <20080215223738.F4FABDE9@kernel>
Date: Fri, 15 Feb 2008 14:37:38 -0800
From: Dave Hansen <haveblue@...ibm.com>
To: linux-kernel@...r.kernel.org
Cc: hch@....de, miklos@...redi.hu, akpm@...l.org,
Dave Hansen <haveblue@...ibm.com>
Subject: [PATCH 13/30] r/o bind mounts: elevate write count for xattr_permission() callers
This basically audits the callers of xattr_permission(), which calls
permission() and can perform writes to the filesystem.
Acked-by: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Dave Hansen <haveblue@...ibm.com>
Signed-off-by: Andrew Morton <akpm@...ux-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 2008-02-15 13:25:49.000000000 -0800
+++ linux-2.6.git-dave/fs/nfsd/nfs4proc.c 2008-02-15 13:25:49.000000000 -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 2008-02-15 13:25:49.000000000 -0800
+++ linux-2.6.git-dave/fs/xattr.c 2008-02-15 13:25:49.000000000 -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.path.mnt);
+ if (error)
+ return error;
error = setxattr(nd.path.dentry, name, value, size, flags);
+ mnt_drop_write(nd.path.mnt);
path_put(&nd.path);
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.path.mnt);
+ if (error)
+ return error;
error = setxattr(nd.path.dentry, name, value, size, flags);
+ mnt_drop_write(nd.path.mnt);
path_put(&nd.path);
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;
}
_
--
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