Re: [PATCH 06/10] lockd: Add helper to sanity check incoming NOTIFY requests

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Sep 17, 2008 at 11:17:57AM -0500, Chuck Lever wrote:
> The NLM performs a silly test to see that incoming NOTIFY requests are
> relatively secure.  Make sure the test works for both AF_INET and AF_INET6
> addresses.

Makes sense.  (Why's the test silly?  If it prevents local users from
telling lockd to drop a client's locks, that seems good.)

--b.

> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> 
>  fs/lockd/svc4proc.c         |    6 ++----
>  fs/lockd/svcproc.c          |    6 ++----
>  include/linux/lockd/lockd.h |   41 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 45 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
> index 9e1c751..6a5ef9f 100644
> --- a/fs/lockd/svc4proc.c
> +++ b/fs/lockd/svc4proc.c
> @@ -432,11 +432,9 @@ nlm4svc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
>  {
>  	struct sockaddr_in	saddr;
>  
> -	memcpy(&saddr, svc_addr_in(rqstp), sizeof(saddr));
> -
>  	dprintk("lockd: SM_NOTIFY     called\n");
> -	if (saddr.sin_addr.s_addr != htonl(INADDR_LOOPBACK)
> -	 || ntohs(saddr.sin_port) >= 1024) {
> +
> +	if (!nlm_privileged_requester(rqstp)) {
>  		char buf[RPC_MAX_ADDRBUFLEN];
>  		printk(KERN_WARNING "lockd: rejected NSM callback from %s\n",
>  				svc_print_addr(rqstp, buf, sizeof(buf)));
> diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
> index fcb7998..62fcfdb 100644
> --- a/fs/lockd/svcproc.c
> +++ b/fs/lockd/svcproc.c
> @@ -464,11 +464,9 @@ nlmsvc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
>  {
>  	struct sockaddr_in	saddr;
>  
> -	memcpy(&saddr, svc_addr_in(rqstp), sizeof(saddr));
> -
>  	dprintk("lockd: SM_NOTIFY     called\n");
> -	if (saddr.sin_addr.s_addr != htonl(INADDR_LOOPBACK)
> -	 || ntohs(saddr.sin_port) >= 1024) {
> +
> +	if (!nlm_privileged_requester(rqstp)) {
>  		char buf[RPC_MAX_ADDRBUFLEN];
>  		printk(KERN_WARNING "lockd: rejected NSM callback from %s\n",
>  				svc_print_addr(rqstp, buf, sizeof(buf)));
> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> index 075095f..409eab4 100644
> --- a/include/linux/lockd/lockd.h
> +++ b/include/linux/lockd/lockd.h
> @@ -280,6 +280,47 @@ static inline struct inode *nlmsvc_file_inode(struct nlm_file *file)
>  	return file->f_file->f_path.dentry->d_inode;
>  }
>  
> +static inline int __nlm_privileged_request4(const struct sockaddr *sap)
> +{
> +	const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
> +	return (sin->sin_addr.s_addr == htonl(INADDR_LOOPBACK)) &&
> +			(ntohs(sin->sin_port) < 1024);
> +}
> +
> +#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
> +static inline int __nlm_privileged_request6(const struct sockaddr *sap)
> +{
> +	const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
> +	return (ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LOOPBACK) &&
> +			(ntohs(sin6->sin6_port) < 1024);
> +}
> +#else	/* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
> +static inline int __nlm_privileged_request6(const struct sockaddr *sap)
> +{
> +	return 0;
> +}
> +#endif	/* defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) */
> +
> +/*
> + * Ensure incoming requests are suitably "secure"
> + *
> + * Return TRUE if sender is local and is connecting via a privileged port;
> + * otherwise return FALSE.
> + */
> +static inline int nlm_privileged_requester(const struct svc_rqst *rqstp)
> +{
> +	const struct sockaddr *sap = svc_addr(rqstp);
> +
> +	switch (sap->sa_family) {
> +	case AF_INET:
> +		return __nlm_privileged_request4(sap);
> +	case AF_INET6:
> +		return __nlm_privileged_request6(sap);
> +	default:
> +		return 0;
> +	}
> +}
> +
>  static inline int __nlm_cmp_addr4(const struct sockaddr *sap1,
>  				  const struct sockaddr *sap2)
>  {
>