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Commit 8f44fcc7 authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont Committed by David S. Miller
Browse files

Phonet: fix flawed "SYN/ACK" logic 



* Do not fail if the peer supports more or less than 3 algorithms.
 * Ignore unknown congestion control algorithms instead of failing.
 * Simplify congestion algorithm negotiation (largest is best).
 * Do not use a static buffer.
 * Fix off-by-two read overflow.
 * Avoid extra memory copy (in addition to skb_copy_bits()).

The previous code really made no sense.

Signed-off-by: default avatarRémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0165d69b

include/net/phonet/pep.h

+1 −0
Original line number Diff line number Diff line
@@ -154,6 +154,7 @@ enum { 
	PN_LEGACY_FLOW_CONTROL,

	PN_ONE_CREDIT_FLOW_CONTROL,

	PN_MULTI_CREDIT_FLOW_CONTROL,

	PN_MAX_FLOW_CONTROL,

};



#define pn_flow_safe(fc) ((fc) >> 1)

net/phonet/pep.c

+47 −78
Original line number Diff line number Diff line
@@ -108,70 +108,6 @@ static int pep_reply(struct sock *sk, struct sk_buff *oskb, 
#define PAD 0x00



#ifdef CONFIG_PHONET_PIPECTRLR

static u8 pipe_negotiate_fc(u8 *host_fc, u8 *remote_fc, int len)

{

	int i, j;

	u8 base_fc, final_fc;



	for (i = 0; i < len; i++) {

		base_fc = host_fc[i];

		for (j = 0; j < len; j++) {

			if (remote_fc[j] == base_fc) {

				final_fc = base_fc;

				goto done;

			}

		}

	}

	return -EINVAL;



done:

	return final_fc;



}



static int pipe_get_flow_info(struct sock *sk, struct sk_buff *skb,

		u8 *pref_rx_fc, u8 *req_tx_fc)

{

	struct pnpipehdr *hdr;

	u8 n_sb;



	if (!pskb_may_pull(skb, sizeof(*hdr) + 4))

		return -EINVAL;



	hdr = pnp_hdr(skb);

	n_sb = hdr->data[4];



	__skb_pull(skb, sizeof(*hdr) + 4);

	while (n_sb > 0) {

		u8 type, buf[3], len = sizeof(buf);

		u8 *data = pep_get_sb(skb, &type, &len, buf);



		if (data == NULL)

			return -EINVAL;



		switch (type) {

		case PN_PIPE_SB_REQUIRED_FC_TX:

			if (len < 3 || (data[2] | data[3] | data[4]) > 3)

				break;

			req_tx_fc[0] = data[2];

			req_tx_fc[1] = data[3];

			req_tx_fc[2] = data[4];

			break;



		case PN_PIPE_SB_PREFERRED_FC_RX:

			if (len < 3 || (data[2] | data[3] | data[4]) > 3)

				break;

			pref_rx_fc[0] = data[2];

			pref_rx_fc[1] = data[3];

			pref_rx_fc[2] = data[4];

			break;



		}

		n_sb--;

	}

	return 0;

}



static int pipe_handler_send_req(struct sock *sk, u8 msg_id, gfp_t priority)

{

	int len;
@@ -661,28 +597,61 @@ static void pipe_destruct(struct sock *sk) 
}



#ifdef CONFIG_PHONET_PIPECTRLR

static u8 pipe_negotiate_fc(const u8 *fcs, unsigned n)

{

	unsigned i;

	u8 final_fc = PN_NO_FLOW_CONTROL;



	for (i = 0; i < n; i++) {

		u8 fc = fcs[i];



		if (fc > final_fc && fc < PN_MAX_FLOW_CONTROL)

			final_fc = fc;

	}

	return final_fc;

}



static int pep_connresp_rcv(struct sock *sk, struct sk_buff *skb)

{

	struct pep_sock *pn = pep_sk(sk);

	u8 host_pref_rx_fc[3] = {3, 2, 1}, host_req_tx_fc[3] = {3, 2, 1};

	u8 remote_pref_rx_fc[3], remote_req_tx_fc[3];

	u8 negotiated_rx_fc, negotiated_tx_fc;



	pipe_get_flow_info(sk, skb, remote_pref_rx_fc,

			remote_req_tx_fc);

	negotiated_tx_fc = pipe_negotiate_fc(remote_req_tx_fc,

			host_pref_rx_fc,

			sizeof(host_pref_rx_fc));

	negotiated_rx_fc = pipe_negotiate_fc(host_req_tx_fc,

			remote_pref_rx_fc,

			sizeof(host_pref_rx_fc));

	struct pnpipehdr *hdr;

	u8 n_sb;



	if (!pskb_pull(skb, sizeof(*hdr) + 4))

		return -EINVAL;



	hdr = pnp_hdr(skb);



	/* Parse sub-blocks */

	n_sb = hdr->data[4];

	while (n_sb > 0) {

		u8 type, buf[6], len = sizeof(buf);

		const u8 *data = pep_get_sb(skb, &type, &len, buf);



		if (data == NULL)

			return -EINVAL;



		switch (type) {

		case PN_PIPE_SB_REQUIRED_FC_TX:

			if (len < 2 || len < data[0])

				break;

			pn->tx_fc = pipe_negotiate_fc(data + 2, len - 2);

			break;



		case PN_PIPE_SB_PREFERRED_FC_RX:

			if (len < 2 || len < data[0])

				break;

			pn->rx_fc = pipe_negotiate_fc(data + 2, len - 2);

			break;



		}

		n_sb--;

	}



	sk->sk_state = TCP_SYN_RECV;

	sk->sk_backlog_rcv = pipe_do_rcv;

	sk->sk_destruct = pipe_destruct;

	pn->rx_credits = 0;

	pn->rx_fc = negotiated_rx_fc;

	pn->tx_fc = negotiated_tx_fc;

	sk->sk_state_change(sk);



	return pipe_handler_send_created_ind(sk, PNS_PIPE_CREATED_IND);