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https://github.com/torvalds/linux
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Phonet: emit errors when a packet cannot be delivered locally
When there is no listener socket for a received packet, send an error back to the sender. Signed-off-by: Remi Denis-Courmont <remi.denis-courmont@nokia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -45,6 +45,38 @@ struct phonethdr {
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__u8 pn_sobj;
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} __attribute__((packed));
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/* Common Phonet payload header */
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struct phonetmsg {
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__u8 pn_trans_id; /* transaction ID */
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__u8 pn_msg_id; /* message type */
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union {
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struct {
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__u8 pn_submsg_id; /* message subtype */
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__u8 pn_data[5];
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} base;
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struct {
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__u16 pn_e_res_id; /* extended resource ID */
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__u8 pn_e_submsg_id; /* message subtype */
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__u8 pn_e_data[3];
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} ext;
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} pn_msg_u;
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};
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#define PN_COMMON_MESSAGE 0xF0
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#define PN_PREFIX 0xE0 /* resource for extended messages */
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#define pn_submsg_id pn_msg_u.base.pn_submsg_id
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#define pn_e_submsg_id pn_msg_u.ext.pn_e_submsg_id
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#define pn_e_res_id pn_msg_u.ext.pn_e_res_id
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#define pn_data pn_msg_u.base.pn_data
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#define pn_e_data pn_msg_u.ext.pn_e_data
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/* data for unreachable errors */
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#define PN_COMM_SERVICE_NOT_IDENTIFIED_RESP 0x01
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#define PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP 0x14
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#define pn_orig_msg_id pn_data[0]
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#define pn_status pn_data[1]
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#define pn_e_orig_msg_id pn_e_data[0]
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#define pn_e_status pn_e_data[1]
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/* Phonet socket address structure */
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struct sockaddr_pn {
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sa_family_t spn_family;
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@ -60,6 +60,11 @@ static inline struct phonethdr *pn_hdr(struct sk_buff *skb)
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return (struct phonethdr *)skb_network_header(skb);
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}
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static inline struct phonetmsg *pn_msg(struct sk_buff *skb)
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{
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return (struct phonetmsg *)skb_transport_header(skb);
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}
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/*
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* Get the other party's sockaddr from received skb. The skb begins
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* with a Phonet header.
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@ -132,7 +132,7 @@ EXPORT_SYMBOL(phonet_header_ops);
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* Prepends an ISI header and sends a datagram.
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*/
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static int pn_send(struct sk_buff *skb, struct net_device *dev,
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u16 dst, u16 src, u8 res)
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u16 dst, u16 src, u8 res, u8 irq)
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{
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struct phonethdr *ph;
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int err;
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@ -163,7 +163,10 @@ static int pn_send(struct sk_buff *skb, struct net_device *dev,
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skb_reset_mac_header(skb);
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skb->pkt_type = PACKET_LOOPBACK;
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skb_orphan(skb);
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netif_rx_ni(skb);
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if (irq)
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netif_rx(skb);
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else
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netif_rx_ni(skb);
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err = 0;
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} else {
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err = dev_hard_header(skb, dev, ntohs(skb->protocol),
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@ -181,6 +184,19 @@ static int pn_send(struct sk_buff *skb, struct net_device *dev,
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return err;
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}
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static int pn_raw_send(const void *data, int len, struct net_device *dev,
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u16 dst, u16 src, u8 res)
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{
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struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
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if (skb == NULL)
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return -ENOMEM;
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skb_reserve(skb, MAX_PHONET_HEADER);
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__skb_put(skb, len);
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skb_copy_to_linear_data(skb, data, len);
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return pn_send(skb, dev, dst, src, res, 1);
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}
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/*
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* Create a Phonet header for the skb and send it out. Returns
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* non-zero error code if failed. The skb is freed then.
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@ -211,7 +227,7 @@ int pn_skb_send(struct sock *sk, struct sk_buff *skb,
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src = pn_object(saddr, pn_obj(src));
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err = pn_send(skb, dev, pn_sockaddr_get_object(target),
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src, pn_sockaddr_get_resource(target));
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src, pn_sockaddr_get_resource(target), 0);
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dev_put(dev);
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return err;
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@ -223,6 +239,73 @@ int pn_skb_send(struct sock *sk, struct sk_buff *skb,
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}
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EXPORT_SYMBOL(pn_skb_send);
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/* Do not send an error message in response to an error message */
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static inline int can_respond(struct sk_buff *skb)
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{
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const struct phonethdr *ph;
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const struct phonetmsg *pm;
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u8 submsg_id;
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if (!pskb_may_pull(skb, 3))
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return 0;
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ph = pn_hdr(skb);
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if (phonet_address_get(skb->dev, ph->pn_rdev) != ph->pn_rdev)
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return 0; /* we are not the destination */
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if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
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return 0;
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ph = pn_hdr(skb); /* re-acquires the pointer */
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pm = pn_msg(skb);
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if (pm->pn_msg_id != PN_COMMON_MESSAGE)
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return 1;
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submsg_id = (ph->pn_res == PN_PREFIX)
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? pm->pn_e_submsg_id : pm->pn_submsg_id;
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if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
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pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
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return 1;
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return 0;
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}
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static int send_obj_unreachable(struct sk_buff *rskb)
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{
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const struct phonethdr *oph = pn_hdr(rskb);
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const struct phonetmsg *opm = pn_msg(rskb);
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struct phonetmsg resp;
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memset(&resp, 0, sizeof(resp));
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resp.pn_trans_id = opm->pn_trans_id;
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resp.pn_msg_id = PN_COMMON_MESSAGE;
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if (oph->pn_res == PN_PREFIX) {
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resp.pn_e_res_id = opm->pn_e_res_id;
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resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
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resp.pn_e_orig_msg_id = opm->pn_msg_id;
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resp.pn_e_status = 0;
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} else {
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resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
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resp.pn_orig_msg_id = opm->pn_msg_id;
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resp.pn_status = 0;
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}
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return pn_raw_send(&resp, sizeof(resp), rskb->dev,
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pn_object(oph->pn_sdev, oph->pn_sobj),
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pn_object(oph->pn_rdev, oph->pn_robj),
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oph->pn_res);
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}
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static int send_reset_indications(struct sk_buff *rskb)
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{
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struct phonethdr *oph = pn_hdr(rskb);
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static const u8 data[4] = {
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0x00 /* trans ID */, 0x10 /* subscribe msg */,
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0x00 /* subscription count */, 0x00 /* dummy */
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};
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return pn_raw_send(data, sizeof(data), rskb->dev,
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pn_object(oph->pn_sdev, 0x00),
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pn_object(oph->pn_rdev, oph->pn_robj), 0x10);
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}
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/* packet type functions */
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/*
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@ -260,8 +343,13 @@ static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
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goto out; /* currently, we cannot be device 0 */
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sk = pn_find_sock_by_sa(&sa);
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if (sk == NULL)
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if (sk == NULL) {
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if (can_respond(skb)) {
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send_obj_unreachable(skb);
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send_reset_indications(skb);
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}
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goto out;
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}
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/* Push data to the socket (or other sockets connected to it). */
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return sk_receive_skb(sk, skb, 0);
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