Subject: Re: [PATCH] Phonet: set the pipe handle using setsockopt

From: Rémi Denis-Courmont <[email-masked]>
Date: Mon, 14 Nov 2011 11:29:58 +0200

Le Lundi 14 Novembre 2011 13:23:30 ext Hemant Vilas RAMDASI a écrit :
> From: Dinesh Kumar Sharma <[email-masked]>
> 
> This provides flexibility to set the pipe handle
> using setsockopt. The pipe can be enabled (if disabled) later
> using ioctl.
> 
> Signed-off-by: Hemant Ramdasi <[email-masked]>
> Signed-off-by: Dinesh Kumar Sharma <[email-masked]>
> ---
>  include/linux/phonet.h |    3 +
>  net/phonet/pep.c       |  105
> +++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 98
> insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/phonet.h b/include/linux/phonet.h
> index 6fb1384..4c00551 100644
> --- a/include/linux/phonet.h
> +++ b/include/linux/phonet.h
> @@ -37,6 +37,8 @@
>  #define PNPIPE_ENCAP		1
>  #define PNPIPE_IFINDEX		2
>  #define PNPIPE_HANDLE		3
> +#define PNPIPE_ENABLE		4
> +#define PNPIPE_INITSTATE	5
> 
>  #define PNADDR_ANY		0
>  #define PNADDR_BROADCAST	0xFC
> @@ -180,6 +182,7 @@ static inline __u8 pn_sockaddr_get_resource(const struct
> sockaddr_pn *spn) /* Phonet device ioctl requests */
>  #ifdef __KERNEL__
>  #define SIOCPNGAUTOCONF		(SIOCDEVPRIVATE + 0)
> +#define SIOPNPIPE_ENABLE	_IO(SIOCPNGAUTOCONF,   1)

Does this even work? I am not an expert on this, but I would think that 
device-private controls are routed to the network device, not the socket. In 
any case, it does not seem right.

> 
>  struct if_phonet_autoconf {
>  	uint8_t device;
> diff --git a/net/phonet/pep.c b/net/phonet/pep.c
> index f17fd84..48339b9 100644
> --- a/net/phonet/pep.c
> +++ b/net/phonet/pep.c
> @@ -533,6 +533,29 @@ static int pep_connresp_rcv(struct sock *sk, struct
> sk_buff *skb) return pipe_handler_send_created_ind(sk);
>  }
> 
> +static int pep_enableresp_rcv(struct sock *sk, struct sk_buff *skb)
> +{
> +	struct pnpipehdr *hdr = pnp_hdr(skb);
> +
> +	if (hdr->error_code != PN_PIPE_NO_ERROR)
> +		return -ECONNREFUSED;
> +
> +	return pep_indicate(sk, PNS_PIPE_ENABLED_IND, 0 /* sub-blocks */,
> +		NULL, 0, GFP_ATOMIC);
> +
> +}
> +
> +static void pipe_start_flow_control(struct sock *sk)
> +{
> +	struct pep_sock *pn = pep_sk(sk);
> +
> +	if (!pn_flow_safe(pn->tx_fc)) {
> +		atomic_set(&pn->tx_credits, 1);
> +		sk->sk_write_space(sk);
> +	}
> +	pipe_grant_credits(sk, GFP_ATOMIC);
> +}
> +
>  /* Queue an skb to an actively connected sock.
>   * Socket lock must be held. */
>  static int pipe_handler_do_rcv(struct sock *sk, struct sk_buff *skb)
> @@ -578,13 +601,25 @@ static int pipe_handler_do_rcv(struct sock *sk, struct
> sk_buff *skb) sk->sk_state = TCP_CLOSE_WAIT;
>  			break;
>  		}
> +		if (pn->init_enable == PN_PIPE_DISABLE)
> +			sk->sk_state = TCP_SYN_RECV;
> +		else {
> +			sk->sk_state = TCP_ESTABLISHED;
> +			pipe_start_flow_control(sk);
> +		}
> +		break;
> 
> -		sk->sk_state = TCP_ESTABLISHED;
> -		if (!pn_flow_safe(pn->tx_fc)) {
> -			atomic_set(&pn->tx_credits, 1);
> -			sk->sk_write_space(sk);
> +	case PNS_PEP_ENABLE_RESP:
> +		if (sk->sk_state != TCP_SYN_SENT)
> +			break;
> +
> +		if (pep_enableresp_rcv(sk, skb)) {
> +			sk->sk_state = TCP_CLOSE_WAIT;
> +			break;
>  		}
> -		pipe_grant_credits(sk, GFP_ATOMIC);
> +
> +		sk->sk_state = TCP_ESTABLISHED;
> +		pipe_start_flow_control(sk);
>  		break;
> 
>  	case PNS_PEP_DISCONNECT_RESP:
> @@ -863,14 +898,31 @@ static int pep_sock_connect(struct sock *sk, struct
> sockaddr *addr, int len) int err;
>  	u8 data[4] = { 0 /* sub-blocks */, PAD, PAD, PAD };
> 
> -	pn->pipe_handle = 1; /* anything but INVALID_HANDLE */
> +	if (pn->pipe_handle == PN_PIPE_INVALID_HANDLE)
> +		pn->pipe_handle = 1; /* anything but INVALID_HANDLE */
> +
>  	err = pipe_handler_request(sk, PNS_PEP_CONNECT_REQ,
> -					PN_PIPE_ENABLE, data, 4);
> -	if (err) {
> -		pn->pipe_handle = PN_PIPE_INVALID_HANDLE;

The current backlog functions assume that pipe_handle = PN_PIPE_INVALID_HANDLE 
if the socket is not yet connected. That's why the old code would clear the 
pipe_handle always on error.

So it is not that simple.

> +				pn->init_enable, data, 4);
> +	if (err)
>  		return err;
> -	}
> +
> +	sk->sk_state = TCP_SYN_SENT;
> +
> +	return 0;
> +}
> +
> +static int pep_sock_enable(struct sock *sk, struct sockaddr *addr, int len)
> +{
> +	int err;
> +
> +	err = pipe_handler_request(sk, PNS_PEP_ENABLE_REQ, PAD,
> +				NULL, 0);
> +
> +	if (err)
> +		return err;
> +
>  	sk->sk_state = TCP_SYN_SENT;
> +
>  	return 0;
>  }
> 
> @@ -894,6 +946,16 @@ static int pep_ioctl(struct sock *sk, int cmd, unsigned
> long arg) answ = 0;
>  		release_sock(sk);
>  		return put_user(answ, (int __user *)arg);
> +		break;
> +
> +	case SIOPNPIPE_ENABLE:
> +		if (sk->sk_state == TCP_SYN_SENT)
> +			return -EBUSY;
> +		else if (sk->sk_state == TCP_ESTABLISHED)
> +			return -EISCONN;
> +		else
> +			return pep_sock_enable(sk, NULL, 0);
> +		break;
>  	}

I strongly suspect insufficient locking here.

> 
>  	return -ENOIOCTLCMD;
> @@ -959,6 +1021,18 @@ static int pep_setsockopt(struct sock *sk, int level,
> int optname, }
>  		goto out_norel;
> 
> +	case PNPIPE_HANDLE:
> +		if ((sk->sk_state == TCP_CLOSE) &&
> +			(val >= 0) && (val < PN_PIPE_INVALID_HANDLE))
> +			pn->pipe_handle = val;
> +		else
> +			err = -EINVAL;
> +		break;

Same problem regarding pipe_handle as above.

> +
> +	case PNPIPE_INITSTATE:
> +		pn->init_enable = !!val;
> +		break;
> +
>  	default:
>  		err = -ENOPROTOOPT;
>  	}
> @@ -994,6 +1068,17 @@ static int pep_getsockopt(struct sock *sk, int level,
> int optname, return -EINVAL;
>  		break;
> 
> +	case PNPIPE_ENABLE:
> +		if (sk->sk_state == TCP_ESTABLISHED)
> +			val = 1;
> +		else
> +			val = 0;
> +		break;

Do you still need this read-only option?

> +
> +	case PNPIPE_INITSTATE:
> +		val = pn->init_enable;
> +		break;
> +
>  	default:
>  		return -ENOPROTOOPT;
>  	}
-- 
Rémi Denis-Courmont
http://www.remlab.net/