linux-kernel - Re: [PATCH 12/14] NFS: Client implementation of Labeled-NFS

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Date:	Fri, 5 Dec 2008 20:39:13 +1100 (EST)
From:	James Morris <jmorris@...ei.org>
To:	"David P. Quigley" <dpquigl@...ho.nsa.gov>
cc:	hch@...radead.org, viro@...iv.linux.org.uk, casey@...aufler-ca.com,
	sds@...ho.nsa.gov, "Matthew N. Dodd" <matthew.dodd@...rta.com>,
	trond.myklebust@....uio.no, bfields@...ldses.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov,
	labeled-nfs@...ux-nfs.org
Subject: Re: [PATCH 12/14] NFS: Client implementation of Labeled-NFS

On Wed, 26 Nov 2008, David P. Quigley wrote:

> +#ifdef CONFIG_NFS_V4_SECURITY_LABEL
> +	if (((nd->flags & LOOKUP_CREATE) != 0) &&
> +	      nfs_server_capable(dir, NFS_CAP_SECURITY_LABEL)) {
> +		status = security_dentry_init_security(dentry,
> +				sattr->ia_mode, &l.label, &l.len);
> +		/* XXX: should this be more fatal? */
> +		if (status == 0)
> +			label = &l;
> +	}
> +#endif

Per the comment, it seems this function should fail and propagate an error 
if status != 0.

> +	memset(&fattr, 0, sizeof(struct nfs_fattr));
> +	nfs_fattr_alloc(&fattr, GFP_KERNEL);

Need to check the return value.

> +	nfs_fattr_alloc(&fattr, GFP_KERNEL);

Ditto.

> +static int decode_attr_security_label(struct xdr_stream *xdr, uint32_t *bitmap, void **ctx, __u32 *ctxlen)
> +{
> +	__u32 len;
> +	__be32 *p;
> +	int rc = 0;
> +
> +	if (unlikely(bitmap[1] & (FATTR4_WORD1_SECURITY_LABEL - 1U)))
> +		return -EIO;
> +	if (likely(bitmap[1] & FATTR4_WORD1_SECURITY_LABEL)) {
> +		READ_BUF(4);
> +		READ32(len);
> +		READ_BUF(len);
> +		if (len < XDR_MAX_NETOBJ) {
> +			if (*ctx != NULL) {
> +				if (*ctxlen < len) {
> +					printk(KERN_ERR
> +						"%s(): ctxlen %d < len %d\n",
> +						__func__, *ctxlen, len);
> +					/* rc = -ENOMEM; */
> +					*ctx = NULL;	/* leak */

Shouldn't the function stop processing and return an error?

> +				} else {
> +					memcpy(*ctx, p, len);
> +				}
> +			}
> +			*ctxlen = len;
> +		} else
> +			printk(KERN_WARNING "%s: label too long (%u)!\n",
> +					__FUNCTION__, len);
> +		bitmap[1] &= ~FATTR4_WORD1_SECURITY_LABEL;
> +	}
> +	return rc;
> +}
> +



-- 
James Morris
<jmorris@...ei.org>
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