On Tue 13-08-19 07:55:06, Mark Salyzyn wrote:
...
> diff --git a/fs/xattr.c b/fs/xattr.c
> index 90dd78f0eb27..71f887518d6f 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
...
> ssize_t
> __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
> - void *value, size_t size)
> + void *value, size_t size, int flags)
> {
> const struct xattr_handler *handler;
> -
> - handler = xattr_resolve_name(inode, &name);
> - if (IS_ERR(handler))
> - return PTR_ERR(handler);
> - if (!handler->get)
> - return -EOPNOTSUPP;
> - return handler->get(handler, dentry, inode, name, value, size);
> -}
> -EXPORT_SYMBOL(__vfs_getxattr);
> -
> -ssize_t
> -vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
> -{
> - struct inode *inode = dentry->d_inode;
> int error;
>
> + if (flags & XATTR_NOSECURITY)
> + goto nolsm;
Hum, is it OK for XATTR_NOSECURITY to skip even the xattr_permission()
check? I understand that for reads of security xattrs it actually does not
matter in practice but conceptually that seems wrong to me as
XATTR_NOSECURITY is supposed to skip just security-module checks to avoid
recursion AFAIU.
> diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h
> index c1395b5bd432..1216d777d210 100644
> --- a/include/uapi/linux/xattr.h
> +++ b/include/uapi/linux/xattr.h
> @@ -17,8 +17,9 @@
> #if __UAPI_DEF_XATTR
> #define __USE_KERNEL_XATTR_DEFS
>
> -#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */
> -#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */
> +#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */
> +#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */
> +#define XATTR_NOSECURITY 0x4 /* get value, do not involve security check */
> #endif
It seems confusing to export XATTR_NOSECURITY definition to userspace when
that is kernel-internal flag. I'd just define it in include/linux/xattr.h
somewhere from the top of flags space (like 0x40000000).
Otherwise the patch looks OK to me (cannot really comment on the security
module aspect of this whole thing though).
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
