Hi,

Now in the GFS2 -nmw git tree. Thanks,

Steve.

On Wed, 2008-07-02 at 21:12 +0200, Miklos Szeredi wrote:
quoted text
> This is the updated version, with the promised renames:
> 
>   gfs2_do_permission -> gfs2_permission
>   gfs2_permission -> gfs2_iop_permission
> 
> Thanks,
> Miklos
> 
> ----
> From: Miklos Szeredi <mszeredi@suse.cz>
> 
> GFS2 calls permission() to verify permissions after locks on the files
> have been taken.
> 
> For this it's sufficient to call gfs2_permission() instead.  This
> results in the following changes:
> 
>   - IS_RDONLY() check is not performed
>   - IS_IMMUTABLE() check is not performed
>   - devcgroup_inode_permission() is not called
>   - security_inode_permission() is not called
> 
> IS_RDONLY() should be unnecessary anyway, as the per-mount read-only
> flag should provide protection against read-only remounts during
> operations.  do_gfs2_set_flags() has been fixed to perform
> mnt_want_write()/mnt_drop_write() to protect against remounting
> read-only.
> 
> IS_IMMUTABLE has been added to gfs2_permission()
> 
> Repeating the security checks seems to be pointless, as they don't
> normally change, and if they do, it's independent of the filesystem
> state.
> 
> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
> ---
>  fs/gfs2/inode.c     |    6 +++---
>  fs/gfs2/inode.h     |    1 +
>  fs/gfs2/ops_file.c  |   11 +++++++++--
>  fs/gfs2/ops_inode.c |   25 +++++++++++++++++--------
>  4 files changed, 30 insertions(+), 13 deletions(-)
> 
> Index: linux-2.6/fs/gfs2/inode.c
> ===================================================================
> --- linux-2.6.orig/fs/gfs2/inode.c	2008-07-01 18:11:32.000000000 +0200
> +++ linux-2.6/fs/gfs2/inode.c	2008-07-01 19:15:59.000000000 +0200
> @@ -504,7 +504,7 @@ struct inode *gfs2_lookupi(struct inode 
>  	}
>  
>  	if (!is_root) {
> -		error = permission(dir, MAY_EXEC, NULL);
> +		error = gfs2_permission(dir, MAY_EXEC);
>  		if (error)
>  			goto out;
>  	}
> @@ -667,7 +667,7 @@ static int create_ok(struct gfs2_inode *
>  {
>  	int error;
>  
> -	error = permission(&dip->i_inode, MAY_WRITE | MAY_EXEC, NULL);
> +	error = gfs2_permission(&dip->i_inode, MAY_WRITE | MAY_EXEC);
>  	if (error)
>  		return error;
>  
> @@ -1134,7 +1134,7 @@ int gfs2_unlink_ok(struct gfs2_inode *di
>  	if (IS_APPEND(&dip->i_inode))
>  		return -EPERM;
>  
> -	error = permission(&dip->i_inode, MAY_WRITE | MAY_EXEC, NULL);
> +	error = gfs2_permission(&dip->i_inode, MAY_WRITE | MAY_EXEC);
>  	if (error)
>  		return error;
>  
> Index: linux-2.6/fs/gfs2/inode.h
> ===================================================================
> --- linux-2.6.orig/fs/gfs2/inode.h	2008-07-01 18:11:32.000000000 +0200
> +++ linux-2.6/fs/gfs2/inode.h	2008-07-01 19:15:59.000000000 +0200
> @@ -91,6 +91,7 @@ int gfs2_rmdiri(struct gfs2_inode *dip, 
>  		struct gfs2_inode *ip);
>  int gfs2_unlink_ok(struct gfs2_inode *dip, const struct qstr *name,
>  		   const struct gfs2_inode *ip);
> +int gfs2_permission(struct inode *inode, int mask);
>  int gfs2_ok_to_move(struct gfs2_inode *this, struct gfs2_inode *to);
>  int gfs2_readlinki(struct gfs2_inode *ip, char **buf, unsigned int *len);
>  int gfs2_glock_nq_atime(struct gfs2_holder *gh);
> Index: linux-2.6/fs/gfs2/ops_file.c
> ===================================================================
> --- linux-2.6.orig/fs/gfs2/ops_file.c	2008-07-01 18:11:32.000000000 +0200
> +++ linux-2.6/fs/gfs2/ops_file.c	2008-07-01 19:15:59.000000000 +0200
> @@ -15,6 +15,7 @@
>  #include <linux/uio.h>
>  #include <linux/blkdev.h>
>  #include <linux/mm.h>
> +#include <linux/mount.h>
>  #include <linux/fs.h>
>  #include <linux/gfs2_ondisk.h>
>  #include <linux/ext2_fs.h>
> @@ -220,10 +221,14 @@ static int do_gfs2_set_flags(struct file
>  	int error;
>  	u32 new_flags, flags;
>  
> -	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
> +	error = mnt_want_write(filp->f_path.mnt);
>  	if (error)
>  		return error;
>  
> +	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
> +	if (error)
> +		goto out_drop_write;
> +
>  	flags = ip->i_di.di_flags;
>  	new_flags = (flags & ~mask) | (reqflags & mask);
>  	if ((new_flags ^ flags) == 0)
> @@ -242,7 +247,7 @@ static int do_gfs2_set_flags(struct file
>  	    !capable(CAP_LINUX_IMMUTABLE))
>  		goto out;
>  	if (!IS_IMMUTABLE(inode)) {
> -		error = permission(inode, MAY_WRITE, NULL);
> +		error = gfs2_permission(inode, MAY_WRITE);
>  		if (error)
>  			goto out;
>  	}
> @@ -272,6 +277,8 @@ out_trans_end:
>  	gfs2_trans_end(sdp);
>  out:
>  	gfs2_glock_dq_uninit(&gh);
> +out_drop_write:
> +	mnt_drop_write(filp->f_path.mnt);
>  	return error;
>  }
>  
> Index: linux-2.6/fs/gfs2/ops_inode.c
> ===================================================================
> --- linux-2.6.orig/fs/gfs2/ops_inode.c	2008-07-01 18:11:32.000000000 +0200
> +++ linux-2.6/fs/gfs2/ops_inode.c	2008-07-01 19:15:59.000000000 +0200
> @@ -163,7 +163,7 @@ static int gfs2_link(struct dentry *old_
>  	if (error)
>  		goto out;
>  
> -	error = permission(dir, MAY_WRITE | MAY_EXEC, NULL);
> +	error = gfs2_permission(dir, MAY_WRITE | MAY_EXEC);
>  	if (error)
>  		goto out_gunlock;
>  
> @@ -669,7 +669,7 @@ static int gfs2_rename(struct inode *odi
>  			}
>  		}
>  	} else {
> -		error = permission(ndir, MAY_WRITE | MAY_EXEC, NULL);
> +		error = gfs2_permission(ndir, MAY_WRITE | MAY_EXEC);
>  		if (error)
>  			goto out_gunlock;
>  
> @@ -704,7 +704,7 @@ static int gfs2_rename(struct inode *odi
>  	/* Check out the dir to be renamed */
>  
>  	if (dir_rename) {
> -		error = permission(odentry->d_inode, MAY_WRITE, NULL);
> +		error = gfs2_permission(odentry->d_inode, MAY_WRITE);
>  		if (error)
>  			goto out_gunlock;
>  	}
> @@ -891,7 +891,7 @@ static void *gfs2_follow_link(struct den
>   * Returns: errno
>   */
>  
> -static int gfs2_permission(struct inode *inode, int mask, struct nameidata *nd)
> +int gfs2_permission(struct inode *inode, int mask)
>  {
>  	struct gfs2_inode *ip = GFS2_I(inode);
>  	struct gfs2_holder i_gh;
> @@ -905,13 +905,22 @@ static int gfs2_permission(struct inode 
>  		unlock = 1;
>  	}
>  
> -	error = generic_permission(inode, mask, gfs2_check_acl);
> +	if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
> +		error = -EACCES;
> +	else
> +		error = generic_permission(inode, mask, gfs2_check_acl);
>  	if (unlock)
>  		gfs2_glock_dq_uninit(&i_gh);
>  
>  	return error;
>  }
>  
> +static int gfs2_iop_permission(struct inode *inode, int mask,
> +			       struct nameidata *nd)
> +{
> +	return gfs2_permission(inode, mask);
> +}
> +
>  static int setattr_size(struct inode *inode, struct iattr *attr)
>  {
>  	struct gfs2_inode *ip = GFS2_I(inode);
> @@ -1141,7 +1150,7 @@ static int gfs2_removexattr(struct dentr
>  }
>  
>  const struct inode_operations gfs2_file_iops = {
> -	.permission = gfs2_permission,
> +	.permission = gfs2_iop_permission,
>  	.setattr = gfs2_setattr,
>  	.getattr = gfs2_getattr,
>  	.setxattr = gfs2_setxattr,
> @@ -1160,7 +1169,7 @@ const struct inode_operations gfs2_dir_i
>  	.rmdir = gfs2_rmdir,
>  	.mknod = gfs2_mknod,
>  	.rename = gfs2_rename,
> -	.permission = gfs2_permission,
> +	.permission = gfs2_iop_permission,
>  	.setattr = gfs2_setattr,
>  	.getattr = gfs2_getattr,
>  	.setxattr = gfs2_setxattr,
> @@ -1172,7 +1181,7 @@ const struct inode_operations gfs2_dir_i
>  const struct inode_operations gfs2_symlink_iops = {
>  	.readlink = gfs2_readlink,
>  	.follow_link = gfs2_follow_link,
> -	.permission = gfs2_permission,
> +	.permission = gfs2_iop_permission,
>  	.setattr = gfs2_setattr,
>  	.getattr = gfs2_getattr,
>  	.setxattr = gfs2_setxattr,

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