linux-kernel - Re: [PATCH 1/1] security: introduce fs caps

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Date:	Tue, 14 Nov 2006 00:04:43 +0300
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	"Serge E. Hallyn" <serue@...ibm.com>
Cc:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Stephen Smalley <sds@...ho.nsa.gov>,
	James Morris <jmorris@...ei.org>,
	Chris Wright <chrisw@...s-sol.org>,
	Andrew Morton <akpm@...l.org>,
	KaiGai Kohei <kaigai@...gai.gr.jp>,
	Chris Friedhoff <chris@...edhoff.org>
Subject: Re: [PATCH 1/1] security: introduce fs caps

On Mon, Nov 13, 2006 at 10:43:26AM -0600, Serge E. Hallyn wrote:
> Quoting Alexey Dobriyan (adobriyan@...il.com):
> > On Wed, Nov 08, 2006 at 05:52:03PM -0600, Serge E. Hallyn wrote:
> > > > > +	__u32 version;
> > > > > +	__u32 effective;
> > > > > +	__u32 permitted;
> > > > > +	__u32 inheritable;
> > > > > +};
> > > > > +
> > > > > +static inline void convert_to_le(struct vfs_cap_data_struct *cap)
> > > > > +{
> > > > > +	cap->version = le32_to_cpu(cap->version);
> > > > > +	cap->effective = le32_to_cpu(cap->effective);
> > > > > +	cap->permitted = le32_to_cpu(cap->permitted);
> > > > > +	cap->inheritable = le32_to_cpu(cap->inheritable);
> > > > > +}
> > > >
> > > > This pretty much defeats sparse endian checking. You will get warnings
> > > > regardless of whether u32 or le32 are used.
> > >
> > > But I don't get any sparse warnings with make C=1.  Am I doing something
> > > wrong?
> >
> > You need (temporarily) to use CF:
> >
> > 	make C=1 CF=-D__CHECK_ENDIAN__ ...
>
> The following patch on top of the existing one eliminates the warning.
> Does it appear consistent with what you were suggesting?

> If it is ok, I'll resend the full patch.

Yes, that's it, modulo:

> --- a/include/linux/capability.h
> +++ b/include/linux/capability.h
> +#ifdef CONFIG_SECURITY_FS_CAPABILITIES

This is exportable header, so no CONFIG_*

> +#define XATTR_CAPS_SUFFIX "capability"
> +#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
> +struct vfs_cap_data_disk {
> +	__le32 version;
> +	__le32 effective;
> +	__le32 permitted;
> +	__le32 inheritable;
> +};
> +#endif
>
>  #ifdef __KERNEL__
>
>  #include <linux/spinlock.h>
>  #include <asm/current.h>
>
> +#ifdef CONFIG_SECURITY_FS_CAPABILITIES
> +struct vfs_cap_data {
> +	__u32 version;
> +	__u32 effective;
> +	__u32 permitted;
> +	__u32 inheritable;
> +};

Now you're in kernel, so you can happily use u32 without undescores.

> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -155,7 +147,8 @@ static int set_file_caps(struct linux_bi
>  {
>  	struct dentry *dentry;
>  	ssize_t rc;

> @@ -178,19 +171,19 @@ static int set_file_caps(struct linux_bi
>  		return rc;
>  	}
>
> -	if (rc != sizeof(cap_struct)) {
> +	if (rc != sizeof(dcaps)) {
>  		printk(KERN_NOTICE "%s: got wrong size for getxattr (%d)\n",
>  					__FUNCTION__, rc);

rc is ssize_t, so "%zd".

-
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