Re: [RFC][PATCH 2/3] ext2: Enable atomic inode security labeling

[Dave Kleikamp <shaggy@austin.ibm.com>]

On Fri, 2005-07-08 at 09:55 -0400, Stephen Smalley wrote:
> This patch modifies ext2 to call the inode_init_security LSM hook to
> obtain the security attribute for a newly created inode and to set the
> resulting attribute on the new inode.  This parallels the existing
> processing for setting ACLs on newly created inodes.
> 
> Please let me know if you have any comments or suggestions for improvement.
> 
>  fs/ext2/ialloc.c         |    5 +++++
>  fs/ext2/xattr.h          |    1 +
>  fs/ext2/xattr_security.c |   22 ++++++++++++++++++++++
>  3 files changed, 28 insertions(+)
> 
> diff -X /home/sds/dontdiff -rup linux-2.6.13.clean/fs/ext2/ialloc.c linux-2.6.13/fs/ext2/ialloc.c
> --- linux-2.6.13.clean/fs/ext2/ialloc.c	2005-06-17 15:48:29.000000000 -0400
> +++ linux-2.6.13/fs/ext2/ialloc.c	2005-07-06 10:55:37.000000000 -0400
> @@ -614,6 +614,11 @@ got:
>  		DQUOT_FREE_INODE(inode);
>  		goto fail2;
>  	}
> +	err = ext2_init_security(inode,dir);

Won't this be unresolved if CONFIG_EXT2_FS_SECURITY is unset?
xattr_security.c won't be compiled at all.  The ext3 patch has the same
problem.

BTW, I'm working on a patch for jfs.  It's a little more complicated
since jfs's xattr code creates a transaction down in the lower level
code.  I'm going to have to restructure it so the caller creates the
transaction and passes down the tid.

> +	if (err) {
> +		DQUOT_FREE_INODE(inode);
> +		goto fail2;
> +	}
>  	mark_inode_dirty(inode);
>  	ext2_debug("allocating inode %lu\n", inode->i_ino);
>  	ext2_preread_inode(inode);
> diff -X /home/sds/dontdiff -rup linux-2.6.13.clean/fs/ext2/xattr.h linux-2.6.13/fs/ext2/xattr.h
> --- linux-2.6.13.clean/fs/ext2/xattr.h	2005-06-17 15:48:29.000000000 -0400
> +++ linux-2.6.13/fs/ext2/xattr.h	2005-07-06 10:55:37.000000000 -0400
> @@ -64,6 +64,7 @@ extern struct xattr_handler ext2_xattr_s
>  
>  extern ssize_t ext2_listxattr(struct dentry *, char *, size_t);
>  
> +extern int ext2_init_security(struct inode *inode, struct inode *dir);
>  extern int ext2_xattr_get(struct inode *, int, const char *, void *, size_t);
>  extern int ext2_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
>  
> diff -X /home/sds/dontdiff -rup linux-2.6.13.clean/fs/ext2/xattr_security.c linux-2.6.13/fs/ext2/xattr_security.c
> --- linux-2.6.13.clean/fs/ext2/xattr_security.c	2005-06-17 15:48:29.000000000 -0400
> +++ linux-2.6.13/fs/ext2/xattr_security.c	2005-07-06 10:56:20.000000000 -0400
> @@ -8,6 +8,7 @@
>  #include <linux/fs.h>
>  #include <linux/smp_lock.h>
>  #include <linux/ext2_fs.h>
> +#include <linux/security.h>
>  #include "xattr.h"
>  
>  static size_t
> @@ -45,6 +46,27 @@ ext2_xattr_security_set(struct inode *in
>  			      value, size, flags);
>  }
>  
> +int
> +ext2_init_security(struct inode *inode, struct inode *dir)
> +{
> +	int err;
> +	size_t len;
> +	void *value;
> +	char *name;
> +
> +	err = security_inode_init_security(inode, dir, &name, &value, &len);
> +	if (err) {
> +		if (err == -EOPNOTSUPP)
> +			return 0;
> +		return err;
> +	}
> +	err = ext2_xattr_set(inode, EXT2_XATTR_INDEX_SECURITY, 
> +			     name, value, len, 0);
> +	kfree(name);
> +	kfree(value);
> +	return err;
> +}
> +
>  struct xattr_handler ext2_xattr_security_handler = {
>  	.prefix	= XATTR_SECURITY_PREFIX,
>  	.list	= ext2_xattr_security_list,
> 
-- 
David Kleikamp
IBM Linux Technology Center



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