// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015, Sony Mobile Communications Inc.
 * Copyright (c) 2013, The Linux Foundation. All rights reserved.
 */
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/qrtr.h>
#include <linux/termios.h>      /* For TIOCINQ/OUTQ */
#include <linux/spinlock.h>
#include <linux/wait.h>

#include <net/sock.h>

#include "qrtr.h"

#define QRTR_PROTO_VER_1 1
#define QRTR_PROTO_VER_2 3

/* auto-bind range */
#define QRTR_MIN_EPH_SOCKET 0x4000
#define QRTR_MAX_EPH_SOCKET 0x7fff
#define QRTR_EPH_PORT_RANGE \
                XA_LIMIT(QRTR_MIN_EPH_SOCKET, QRTR_MAX_EPH_SOCKET)

#define QRTR_PORT_CTRL_LEGACY 0xffff

/**
 * struct qrtr_hdr_v1 - (I|R)PCrouter packet header version 1
 * @version: protocol version
 * @type: packet type; one of QRTR_TYPE_*
 * @src_node_id: source node
 * @src_port_id: source port
 * @confirm_rx: boolean; whether a resume-tx packet should be send in reply
 * @size: length of packet, excluding this header
 * @dst_node_id: destination node
 * @dst_port_id: destination port
 */
struct qrtr_hdr_v1 {
        __le32 version;
        __le32 type;
        __le32 src_node_id;
        __le32 src_port_id;
        __le32 confirm_rx;
        __le32 size;
        __le32 dst_node_id;
        __le32 dst_port_id;
} __packed;

/**
 * struct qrtr_hdr_v2 - (I|R)PCrouter packet header later versions
 * @version: protocol version
 * @type: packet type; one of QRTR_TYPE_*
 * @flags: bitmask of QRTR_FLAGS_*
 * @optlen: length of optional header data
 * @size: length of packet, excluding this header and optlen
 * @src_node_id: source node
 * @src_port_id: source port
 * @dst_node_id: destination node
 * @dst_port_id: destination port
 */
struct qrtr_hdr_v2 {
        u8 version;
        u8 type;
        u8 flags;
        u8 optlen;
        __le32 size;
        __le16 src_node_id;
        __le16 src_port_id;
        __le16 dst_node_id;
        __le16 dst_port_id;
};

#define QRTR_FLAGS_CONFIRM_RX   BIT(0)

struct qrtr_cb {
        u32 src_node;
        u32 src_port;
        u32 dst_node;
        u32 dst_port;

        u8 type;
        u8 confirm_rx;
};

#define QRTR_HDR_MAX_SIZE max_t(size_t, sizeof(struct qrtr_hdr_v1), \
                                        sizeof(struct qrtr_hdr_v2))

struct qrtr_sock {
        /* WARNING: sk must be the first member */
        struct sock sk;
        struct sockaddr_qrtr us;
        struct sockaddr_qrtr peer;
};

static inline struct qrtr_sock *qrtr_sk(struct sock *sk)
{
        BUILD_BUG_ON(offsetof(struct qrtr_sock, sk) != 0);
        return container_of(sk, struct qrtr_sock, sk);
}

static unsigned int qrtr_local_nid = 1;

/* for node ids */
static RADIX_TREE(qrtr_nodes, GFP_ATOMIC);
static DEFINE_SPINLOCK(qrtr_nodes_lock);
/* broadcast list */
static LIST_HEAD(qrtr_all_nodes);
/* lock for qrtr_all_nodes and node reference */
static DEFINE_MUTEX(qrtr_node_lock);

/* local port allocation management */
static DEFINE_XARRAY_ALLOC(qrtr_ports);

/**
 * struct qrtr_node - endpoint node
 * @ep_lock: lock for endpoint management and callbacks
 * @ep: endpoint
 * @ref: reference count for node
 * @nid: node id
 * @qrtr_tx_flow: xarray of qrtr_tx_flow, keyed by node << 32 | port
 * @qrtr_tx_lock: lock for qrtr_tx_flow inserts
 * @rx_queue: receive queue
 * @item: list item for broadcast list
 */
struct qrtr_node {
        struct mutex ep_lock;
        struct qrtr_endpoint *ep;
        struct kref ref;
        unsigned int nid;

        struct xarray qrtr_tx_flow;
        struct mutex qrtr_tx_lock; /* for qrtr_tx_flow */

        struct sk_buff_head rx_queue;
        struct list_head item;
};

/**
 * struct qrtr_tx_flow - tx flow control
 * @resume_tx: waiters for a resume tx from the remote
 * @pending: number of waiting senders
 * @tx_failed: indicates that a message with confirm_rx flag was lost
 */
struct qrtr_tx_flow {
        struct wait_queue_head resume_tx;
        int pending;
        int tx_failed;
};

#define QRTR_TX_FLOW_HIGH       10
#define QRTR_TX_FLOW_LOW        5

static int qrtr_local_enqueue(struct qrtr_node *node, struct sk_buff *skb,
                              int type, struct sockaddr_qrtr *from,
                              struct sockaddr_qrtr *to);
static int qrtr_bcast_enqueue(struct qrtr_node *node, struct sk_buff *skb,
                              int type, struct sockaddr_qrtr *from,
                              struct sockaddr_qrtr *to);
static struct qrtr_sock *qrtr_port_lookup(int port);
static void qrtr_port_put(struct qrtr_sock *ipc);

/* Release node resources and free the node.
 *
 * Do not call directly, use qrtr_node_release.  To be used with
 * kref_put_mutex.  As such, the node mutex is expected to be locked on call.
 */
static void __qrtr_node_release(struct kref *kref)
{
        struct qrtr_node *node = container_of(kref, struct qrtr_node, ref);
        struct radix_tree_iter iter;
        struct qrtr_tx_flow *flow;
        unsigned long flags;
        void __rcu **slot;
        unsigned long index;

        spin_lock_irqsave(&qrtr_nodes_lock, flags);
        /* If the node is a bridge for other nodes, there are possibly
         * multiple entries pointing to our released node, delete them all.
         */
        radix_tree_for_each_slot(slot, &qrtr_nodes, &iter, 0) {
                if (*slot == node)
                        radix_tree_iter_delete(&qrtr_nodes, &iter, slot);
        }
        spin_unlock_irqrestore(&qrtr_nodes_lock, flags);

        list_del(&node->item);
        mutex_unlock(&qrtr_node_lock);

        skb_queue_purge(&node->rx_queue);

        /* Free tx flow counters */
        xa_for_each(&node->qrtr_tx_flow, index, flow)
                kfree(flow);
        xa_destroy(&node->qrtr_tx_flow);
        kfree(node);
}

/* Increment reference to node. */
static struct qrtr_node *qrtr_node_acquire(struct qrtr_node *node)
{
        if (node)
                kref_get(&node->ref);
        return node;
}

/* Decrement reference to node and release as necessary. */
static void qrtr_node_release(struct qrtr_node *node)
{
        if (!node)
                return;
        kref_put_mutex(&node->ref, __qrtr_node_release, &qrtr_node_lock);
}

/**
 * qrtr_tx_resume() - reset flow control counter
 * @node:       qrtr_node that the QRTR_TYPE_RESUME_TX packet arrived on
 * @skb:        resume_tx packet
 */
static void qrtr_tx_resume(struct qrtr_node *node, struct sk_buff *skb)
{
        struct qrtr_ctrl_pkt *pkt = (struct qrtr_ctrl_pkt *)skb->data;
        u64 remote_node = le32_to_cpu(pkt->client.node);
        u32 remote_port = le32_to_cpu(pkt->client.port);
        struct qrtr_tx_flow *flow;
        unsigned long key;

        key = remote_node << 32 | remote_port;

        flow = xa_load(&node->qrtr_tx_flow, key);
        if (flow) {
                spin_lock(&flow->resume_tx.lock);
                flow->pending = 0;
                spin_unlock(&flow->resume_tx.lock);
                wake_up_interruptible_all(&flow->resume_tx);
        }

        consume_skb(skb);
}

/**
 * qrtr_tx_wait() - flow control for outgoing packets
 * @node:       qrtr_node that the packet is to be send to
 * @dest_node:  node id of the destination
 * @dest_port:  port number of the destination
 * @type:       type of message
 *
 * The flow control scheme is based around the low and high "watermarks". When
 * the low watermark is passed the confirm_rx flag is set on the outgoing
 * message, which will trigger the remote to send a control message of the type
 * QRTR_TYPE_RESUME_TX to reset the counter. If the high watermark is hit
 * further transmision should be paused.
 *
 * Return: 1 if confirm_rx should be set, 0 otherwise or errno failure
 */
static int qrtr_tx_wait(struct qrtr_node *node, int dest_node, int dest_port,
                        int type)
{
        unsigned long key = (u64)dest_node << 32 | dest_port;
        struct qrtr_tx_flow *flow;
        int confirm_rx = 0;
        int ret;

        /* Never set confirm_rx on non-data packets */
        if (type != QRTR_TYPE_DATA)
                return 0;

        mutex_lock(&node->qrtr_tx_lock);
        flow = xa_load(&node->qrtr_tx_flow, key);
        if (!flow) {
                flow = kzalloc_obj(*flow);
                if (flow) {
                        init_waitqueue_head(&flow->resume_tx);
                        if (xa_err(xa_store(&node->qrtr_tx_flow, key, flow,
                                            GFP_KERNEL))) {
                                kfree(flow);
                                flow = NULL;
                        }
                }
        }
        mutex_unlock(&node->qrtr_tx_lock);

        /* Set confirm_rx if we where unable to find and allocate a flow */
        if (!flow)
                return 1;

        spin_lock_irq(&flow->resume_tx.lock);
        ret = wait_event_interruptible_locked_irq(flow->resume_tx,
                                                  flow->pending < QRTR_TX_FLOW_HIGH ||
                                                  flow->tx_failed ||
                                                  !node->ep);
        if (ret < 0) {
                confirm_rx = ret;
        } else if (!node->ep) {
                confirm_rx = -EPIPE;
        } else if (flow->tx_failed) {
                flow->tx_failed = 0;
                confirm_rx = 1;
        } else {
                flow->pending++;
                confirm_rx = flow->pending == QRTR_TX_FLOW_LOW;
        }
        spin_unlock_irq(&flow->resume_tx.lock);

        return confirm_rx;
}

/**
 * qrtr_tx_flow_failed() - flag that tx of confirm_rx flagged messages failed
 * @node:       qrtr_node that the packet is to be send to
 * @dest_node:  node id of the destination
 * @dest_port:  port number of the destination
 *
 * Signal that the transmission of a message with confirm_rx flag failed. The
 * flow's "pending" counter will keep incrementing towards QRTR_TX_FLOW_HIGH,
 * at which point transmission would stall forever waiting for the resume TX
 * message associated with the dropped confirm_rx message.
 * Work around this by marking the flow as having a failed transmission and
 * cause the next transmission attempt to be sent with the confirm_rx.
 */
static void qrtr_tx_flow_failed(struct qrtr_node *node, int dest_node,
                                int dest_port)
{
        unsigned long key = (u64)dest_node << 32 | dest_port;
        struct qrtr_tx_flow *flow;

        flow = xa_load(&node->qrtr_tx_flow, key);
        if (flow) {
                spin_lock_irq(&flow->resume_tx.lock);
                flow->tx_failed = 1;
                spin_unlock_irq(&flow->resume_tx.lock);
        }
}

/* Pass an outgoing packet socket buffer to the endpoint driver. */
static int qrtr_node_enqueue(struct qrtr_node *node, struct sk_buff *skb,
                             int type, struct sockaddr_qrtr *from,
                             struct sockaddr_qrtr *to)
{
        struct qrtr_hdr_v1 *hdr;
        size_t len = skb->len;
        int rc, confirm_rx;

        confirm_rx = qrtr_tx_wait(node, to->sq_node, to->sq_port, type);
        if (confirm_rx < 0) {
                kfree_skb(skb);
                return confirm_rx;
        }

        hdr = skb_push(skb, sizeof(*hdr));
        hdr->version = cpu_to_le32(QRTR_PROTO_VER_1);
        hdr->type = cpu_to_le32(type);
        hdr->src_node_id = cpu_to_le32(from->sq_node);
        hdr->src_port_id = cpu_to_le32(from->sq_port);
        if (to->sq_port == QRTR_PORT_CTRL) {
                hdr->dst_node_id = cpu_to_le32(node->nid);
                hdr->dst_port_id = cpu_to_le32(QRTR_PORT_CTRL);
        } else {
                hdr->dst_node_id = cpu_to_le32(to->sq_node);
                hdr->dst_port_id = cpu_to_le32(to->sq_port);
        }

        hdr->size = cpu_to_le32(len);
        hdr->confirm_rx = !!confirm_rx;

        rc = skb_put_padto(skb, ALIGN(len, 4) + sizeof(*hdr));

        if (!rc) {
                mutex_lock(&node->ep_lock);
                rc = -ENODEV;
                if (node->ep)
                        rc = node->ep->xmit(node->ep, skb);
                else
                        kfree_skb(skb);
                mutex_unlock(&node->ep_lock);
        }
        /* Need to ensure that a subsequent message carries the otherwise lost
         * confirm_rx flag if we dropped this one */
        if (rc && confirm_rx)
                qrtr_tx_flow_failed(node, to->sq_node, to->sq_port);

        return rc;
}

/* Lookup node by id.
 *
 * callers must release with qrtr_node_release()
 */
static struct qrtr_node *qrtr_node_lookup(unsigned int nid)
{
        struct qrtr_node *node;
        unsigned long flags;

        mutex_lock(&qrtr_node_lock);
        spin_lock_irqsave(&qrtr_nodes_lock, flags);
        node = radix_tree_lookup(&qrtr_nodes, nid);
        node = qrtr_node_acquire(node);
        spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
        mutex_unlock(&qrtr_node_lock);

        return node;
}

/* Assign node id to node.
 *
 * This is mostly useful for automatic node id assignment, based on
 * the source id in the incoming packet.
 */
static void qrtr_node_assign(struct qrtr_node *node, unsigned int nid)
{
        unsigned long flags;

        if (nid == QRTR_EP_NID_AUTO)
                return;

        spin_lock_irqsave(&qrtr_nodes_lock, flags);
        radix_tree_insert(&qrtr_nodes, nid, node);
        if (node->nid == QRTR_EP_NID_AUTO)
                node->nid = nid;
        spin_unlock_irqrestore(&qrtr_nodes_lock, flags);
}

/**
 * qrtr_endpoint_post() - post incoming data
 * @ep: endpoint handle
 * @data: data pointer
 * @len: size of data in bytes
 *
 * Return: 0 on success; negative error code on failure
 */
int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
{
        struct qrtr_node *node = ep->node;
        const struct qrtr_hdr_v1 *v1;
        const struct qrtr_hdr_v2 *v2;
        struct qrtr_sock *ipc;
        struct sk_buff *skb;
        struct qrtr_cb *cb;
        size_t size;
        unsigned int ver;
        size_t hdrlen;

        if (len == 0 || len & 3)
                return -EINVAL;

        skb = __netdev_alloc_skb(NULL, len, GFP_ATOMIC | __GFP_NOWARN);
        if (!skb)
                return -ENOMEM;

        cb = (struct qrtr_cb *)skb->cb;

        /* Version field in v1 is little endian, so this works for both cases */
        ver = *(u8*)data;

        switch (ver) {
        case QRTR_PROTO_VER_1:
                if (len < sizeof(*v1))
                        goto err;
                v1 = data;
                hdrlen = sizeof(*v1);

                cb->type = le32_to_cpu(v1->type);
                cb->src_node = le32_to_cpu(v1->src_node_id);
                cb->src_port = le32_to_cpu(v1->src_port_id);
                cb->confirm_rx = !!v1->confirm_rx;
                cb->dst_node = le32_to_cpu(v1->dst_node_id);
                cb->dst_port = le32_to_cpu(v1->dst_port_id);

                size = le32_to_cpu(v1->size);
                break;
        case QRTR_PROTO_VER_2:
                if (len < sizeof(*v2))
                        goto err;
                v2 = data;
                hdrlen = sizeof(*v2) + v2->optlen;

                cb->type = v2->type;
                cb->confirm_rx = !!(v2->flags & QRTR_FLAGS_CONFIRM_RX);
                cb->src_node = le16_to_cpu(v2->src_node_id);
                cb->src_port = le16_to_cpu(v2->src_port_id);
                cb->dst_node = le16_to_cpu(v2->dst_node_id);
                cb->dst_port = le16_to_cpu(v2->dst_port_id);

                if (cb->src_port == (u16)QRTR_PORT_CTRL)
                        cb->src_port = QRTR_PORT_CTRL;
                if (cb->dst_port == (u16)QRTR_PORT_CTRL)
                        cb->dst_port = QRTR_PORT_CTRL;

                size = le32_to_cpu(v2->size);
                break;
        default:
                pr_err("qrtr: Invalid version %d\n", ver);
                goto err;
        }

        if (cb->dst_port == QRTR_PORT_CTRL_LEGACY)
                cb->dst_port = QRTR_PORT_CTRL;

        if (!size || len != ALIGN(size, 4) + hdrlen)
                goto err;

        if ((cb->type == QRTR_TYPE_NEW_SERVER ||
             cb->type == QRTR_TYPE_RESUME_TX) &&
            size < sizeof(struct qrtr_ctrl_pkt))
                goto err;

        if (cb->dst_port != QRTR_PORT_CTRL && cb->type != QRTR_TYPE_DATA &&
            cb->type != QRTR_TYPE_RESUME_TX)
                goto err;

        skb_put_data(skb, data + hdrlen, size);

        qrtr_node_assign(node, cb->src_node);

        if (cb->type == QRTR_TYPE_NEW_SERVER) {
                /* Remote node endpoint can bridge other distant nodes */
                const struct qrtr_ctrl_pkt *pkt;

                pkt = data + hdrlen;
                qrtr_node_assign(node, le32_to_cpu(pkt->server.node));
        }

        if (cb->type == QRTR_TYPE_RESUME_TX) {
                qrtr_tx_resume(node, skb);
        } else {
                ipc = qrtr_port_lookup(cb->dst_port);
                if (!ipc)
                        goto err;

                if (sock_queue_rcv_skb(&ipc->sk, skb)) {
                        qrtr_port_put(ipc);
                        goto err;
                }

                qrtr_port_put(ipc);
        }

        return 0;

err:
        kfree_skb(skb);
        return -EINVAL;

}
EXPORT_SYMBOL_GPL(qrtr_endpoint_post);

/**
 * qrtr_alloc_ctrl_packet() - allocate control packet skb
 * @pkt: reference to qrtr_ctrl_pkt pointer
 * @flags: the type of memory to allocate
 *
 * Returns newly allocated sk_buff, or NULL on failure
 *
 * This function allocates a sk_buff large enough to carry a qrtr_ctrl_pkt and
 * on success returns a reference to the control packet in @pkt.
 */
static struct sk_buff *qrtr_alloc_ctrl_packet(struct qrtr_ctrl_pkt **pkt,
                                              gfp_t flags)
{
        const int pkt_len = sizeof(struct qrtr_ctrl_pkt);
        struct sk_buff *skb;

        skb = alloc_skb(QRTR_HDR_MAX_SIZE + pkt_len, flags);
        if (!skb)
                return NULL;

        skb_reserve(skb, QRTR_HDR_MAX_SIZE);
        *pkt = skb_put_zero(skb, pkt_len);

        return skb;
}

/**
 * qrtr_endpoint_register() - register a new endpoint
 * @ep: endpoint to register
 * @nid: desired node id; may be QRTR_EP_NID_AUTO for auto-assignment
 * Return: 0 on success; negative error code on failure
 *
 * The specified endpoint must have the xmit function pointer set on call.
 */
int qrtr_endpoint_register(struct qrtr_endpoint *ep, unsigned int nid)
{
        struct qrtr_node *node;

        if (!ep || !ep->xmit)
                return -EINVAL;

        node = kzalloc_obj(*node);
        if (!node)
                return -ENOMEM;

        kref_init(&node->ref);
        mutex_init(&node->ep_lock);
        skb_queue_head_init(&node->rx_queue);
        node->nid = QRTR_EP_NID_AUTO;
        node->ep = ep;

        xa_init(&node->qrtr_tx_flow);
        mutex_init(&node->qrtr_tx_lock);

        qrtr_node_assign(node, nid);

        mutex_lock(&qrtr_node_lock);
        list_add(&node->item, &qrtr_all_nodes);
        mutex_unlock(&qrtr_node_lock);
        ep->node = node;

        return 0;
}
EXPORT_SYMBOL_GPL(qrtr_endpoint_register);

/**
 * qrtr_endpoint_unregister - unregister endpoint
 * @ep: endpoint to unregister
 */
void qrtr_endpoint_unregister(struct qrtr_endpoint *ep)
{
        struct qrtr_node *node = ep->node;
        struct sockaddr_qrtr src = {AF_QIPCRTR, node->nid, QRTR_PORT_CTRL};
        struct sockaddr_qrtr dst = {AF_QIPCRTR, qrtr_local_nid, QRTR_PORT_CTRL};
        struct radix_tree_iter iter;
        struct qrtr_ctrl_pkt *pkt;
        struct qrtr_tx_flow *flow;
        struct sk_buff *skb;
        unsigned long flags;
        unsigned long index;
        void __rcu **slot;

        mutex_lock(&node->ep_lock);
        node->ep = NULL;
        mutex_unlock(&node->ep_lock);

        /* Notify the local controller about the event */
        spin_lock_irqsave(&qrtr_nodes_lock, flags);
        radix_tree_for_each_slot(slot, &qrtr_nodes, &iter, 0) {
                if (*slot != node)
                        continue;
                src.sq_node = iter.index;
                skb = qrtr_alloc_ctrl_packet(&pkt, GFP_ATOMIC);
                if (skb) {
                        pkt->cmd = cpu_to_le32(QRTR_TYPE_BYE);
                        qrtr_local_enqueue(NULL, skb, QRTR_TYPE_BYE, &src, &dst);
                }
        }
        spin_unlock_irqrestore(&qrtr_nodes_lock, flags);

        /* Wake up any transmitters waiting for resume-tx from the node */
        mutex_lock(&node->qrtr_tx_lock);
        xa_for_each(&node->qrtr_tx_flow, index, flow)
                wake_up_interruptible_all(&flow->resume_tx);
        mutex_unlock(&node->qrtr_tx_lock);

        qrtr_node_release(node);
        ep->node = NULL;
}
EXPORT_SYMBOL_GPL(qrtr_endpoint_unregister);

/* Lookup socket by port.
 *
 * Callers must release with qrtr_port_put()
 */
static struct qrtr_sock *qrtr_port_lookup(int port)
{
        struct qrtr_sock *ipc;

        if (port == QRTR_PORT_CTRL)
                port = 0;

        rcu_read_lock();
        ipc = xa_load(&qrtr_ports, port);
        if (ipc)
                sock_hold(&ipc->sk);
        rcu_read_unlock();

        return ipc;
}

/* Release acquired socket. */
static void qrtr_port_put(struct qrtr_sock *ipc)
{
        sock_put(&ipc->sk);
}

/* Remove port assignment. */
static void qrtr_port_remove(struct qrtr_sock *ipc)
{
        struct qrtr_ctrl_pkt *pkt;
        struct sk_buff *skb;
        int port = ipc->us.sq_port;
        struct sockaddr_qrtr to;

        to.sq_family = AF_QIPCRTR;
        to.sq_node = QRTR_NODE_BCAST;
        to.sq_port = QRTR_PORT_CTRL;

        skb = qrtr_alloc_ctrl_packet(&pkt, GFP_KERNEL);
        if (skb) {
                pkt->cmd = cpu_to_le32(QRTR_TYPE_DEL_CLIENT);
                pkt->client.node = cpu_to_le32(ipc->us.sq_node);
                pkt->client.port = cpu_to_le32(ipc->us.sq_port);

                skb_set_owner_w(skb, &ipc->sk);
                qrtr_bcast_enqueue(NULL, skb, QRTR_TYPE_DEL_CLIENT, &ipc->us,
                                   &to);
        }

        if (port == QRTR_PORT_CTRL)
                port = 0;

        __sock_put(&ipc->sk);

        xa_erase(&qrtr_ports, port);

        /* Ensure that if qrtr_port_lookup() did enter the RCU read section we
         * wait for it to up increment the refcount */
        synchronize_rcu();
}

/* Assign port number to socket.
 *
 * Specify port in the integer pointed to by port, and it will be adjusted
 * on return as necesssary.
 *
 * Port may be:
 *   0: Assign ephemeral port in [QRTR_MIN_EPH_SOCKET, QRTR_MAX_EPH_SOCKET]
 *   <QRTR_MIN_EPH_SOCKET: Specified; requires CAP_NET_ADMIN
 *   >QRTR_MIN_EPH_SOCKET: Specified; available to all
 */
static int qrtr_port_assign(struct qrtr_sock *ipc, int *port)
{
        int rc;

        if (!*port) {
                rc = xa_alloc(&qrtr_ports, port, ipc, QRTR_EPH_PORT_RANGE,
                                GFP_KERNEL);
        } else if (*port < QRTR_MIN_EPH_SOCKET && !capable(CAP_NET_ADMIN)) {
                rc = -EACCES;
        } else if (*port == QRTR_PORT_CTRL) {
                rc = xa_insert(&qrtr_ports, 0, ipc, GFP_KERNEL);
        } else {
                rc = xa_insert(&qrtr_ports, *port, ipc, GFP_KERNEL);
        }

        if (rc == -EBUSY)
                return -EADDRINUSE;
        else if (rc < 0)
                return rc;

        sock_hold(&ipc->sk);

        return 0;
}

/* Reset all non-control ports */
static void qrtr_reset_ports(void)
{
        struct qrtr_sock *ipc;
        unsigned long index;

        rcu_read_lock();
        xa_for_each_start(&qrtr_ports, index, ipc, 1) {
                sock_hold(&ipc->sk);
                ipc->sk.sk_err = ENETRESET;
                sk_error_report(&ipc->sk);
                sock_put(&ipc->sk);
        }
        rcu_read_unlock();
}

/* Bind socket to address.
 *
 * Socket should be locked upon call.
 */
static int __qrtr_bind(struct socket *sock,
                       const struct sockaddr_qrtr *addr, int zapped)
{
        struct qrtr_sock *ipc = qrtr_sk(sock->sk);
        struct sock *sk = sock->sk;
        int port;
        int rc;

        /* rebinding ok */
        if (!zapped && addr->sq_port == ipc->us.sq_port)
                return 0;

        port = addr->sq_port;
        rc = qrtr_port_assign(ipc, &port);
        if (rc)
                return rc;

        /* unbind previous, if any */
        if (!zapped)
                qrtr_port_remove(ipc);
        ipc->us.sq_port = port;

        sock_reset_flag(sk, SOCK_ZAPPED);

        /* Notify all open ports about the new controller */
        if (port == QRTR_PORT_CTRL)
                qrtr_reset_ports();

        return 0;
}

/* Auto bind to an ephemeral port. */
static int qrtr_autobind(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct sockaddr_qrtr addr;

        if (!sock_flag(sk, SOCK_ZAPPED))
                return 0;

        addr.sq_family = AF_QIPCRTR;
        addr.sq_node = qrtr_local_nid;
        addr.sq_port = 0;

        return __qrtr_bind(sock, &addr, 1);
}

/* Bind socket to specified sockaddr. */
static int qrtr_bind(struct socket *sock, struct sockaddr_unsized *saddr, int len)
{
        DECLARE_SOCKADDR(struct sockaddr_qrtr *, addr, saddr);
        struct qrtr_sock *ipc = qrtr_sk(sock->sk);
        struct sock *sk = sock->sk;
        int rc;

        if (len < sizeof(*addr) || addr->sq_family != AF_QIPCRTR)
                return -EINVAL;

        if (addr->sq_node != ipc->us.sq_node)
                return -EINVAL;

        lock_sock(sk);
        rc = __qrtr_bind(sock, addr, sock_flag(sk, SOCK_ZAPPED));
        release_sock(sk);

        return rc;
}

/* Queue packet to local peer socket. */
static int qrtr_local_enqueue(struct qrtr_node *node, struct sk_buff *skb,
                              int type, struct sockaddr_qrtr *from,
                              struct sockaddr_qrtr *to)
{
        struct qrtr_sock *ipc;
        struct qrtr_cb *cb;

        ipc = qrtr_port_lookup(to->sq_port);
        if (!ipc || &ipc->sk == skb->sk) { /* do not send to self */
                if (ipc)
                        qrtr_port_put(ipc);
                kfree_skb(skb);
                return -ENODEV;
        }

        cb = (struct qrtr_cb *)skb->cb;
        cb->src_node = from->sq_node;
        cb->src_port = from->sq_port;

        if (sock_queue_rcv_skb(&ipc->sk, skb)) {
                qrtr_port_put(ipc);
                kfree_skb(skb);
                return -ENOSPC;
        }

        qrtr_port_put(ipc);

        return 0;
}

/* Queue packet for broadcast. */
static int qrtr_bcast_enqueue(struct qrtr_node *node, struct sk_buff *skb,
                              int type, struct sockaddr_qrtr *from,
                              struct sockaddr_qrtr *to)
{
        struct sk_buff *skbn;

        mutex_lock(&qrtr_node_lock);
        list_for_each_entry(node, &qrtr_all_nodes, item) {
                skbn = pskb_copy(skb, GFP_KERNEL);
                if (!skbn)
                        break;
                skb_set_owner_w(skbn, skb->sk);
                qrtr_node_enqueue(node, skbn, type, from, to);
        }
        mutex_unlock(&qrtr_node_lock);

        qrtr_local_enqueue(NULL, skb, type, from, to);

        return 0;
}

static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
{
        DECLARE_SOCKADDR(struct sockaddr_qrtr *, addr, msg->msg_name);
        int (*enqueue_fn)(struct qrtr_node *, struct sk_buff *, int,
                          struct sockaddr_qrtr *, struct sockaddr_qrtr *);
        __le32 qrtr_type = cpu_to_le32(QRTR_TYPE_DATA);
        struct qrtr_sock *ipc = qrtr_sk(sock->sk);
        struct sock *sk = sock->sk;
        struct qrtr_node *node;
        struct sk_buff *skb;
        size_t plen;
        u32 type;
        int rc;

        if (msg->msg_flags & ~(MSG_DONTWAIT))
                return -EINVAL;

        if (len > 65535)
                return -EMSGSIZE;

        lock_sock(sk);

        if (addr) {
                if (msg->msg_namelen < sizeof(*addr)) {
                        release_sock(sk);
                        return -EINVAL;
                }

                if (addr->sq_family != AF_QIPCRTR) {
                        release_sock(sk);
                        return -EINVAL;
                }

                rc = qrtr_autobind(sock);
                if (rc) {
                        release_sock(sk);
                        return rc;
                }
        } else if (sk->sk_state == TCP_ESTABLISHED) {
                addr = &ipc->peer;
        } else {
                release_sock(sk);
                return -ENOTCONN;
        }

        node = NULL;
        if (addr->sq_node == QRTR_NODE_BCAST) {
                if (addr->sq_port != QRTR_PORT_CTRL &&
                    qrtr_local_nid != QRTR_NODE_BCAST) {
                        release_sock(sk);
                        return -ENOTCONN;
                }
                enqueue_fn = qrtr_bcast_enqueue;
        } else if (addr->sq_node == ipc->us.sq_node) {
                enqueue_fn = qrtr_local_enqueue;
        } else {
                node = qrtr_node_lookup(addr->sq_node);
                if (!node) {
                        release_sock(sk);
                        return -ECONNRESET;
                }
                enqueue_fn = qrtr_node_enqueue;
        }

        plen = (len + 3) & ~3;
        skb = sock_alloc_send_skb(sk, plen + QRTR_HDR_MAX_SIZE,
                                  msg->msg_flags & MSG_DONTWAIT, &rc);
        if (!skb) {
                rc = -ENOMEM;
                goto out_node;
        }

        skb_reserve(skb, QRTR_HDR_MAX_SIZE);

        rc = memcpy_from_msg(skb_put(skb, len), msg, len);
        if (rc) {
                kfree_skb(skb);
                goto out_node;
        }

        if (ipc->us.sq_port == QRTR_PORT_CTRL) {
                if (len < 4) {
                        rc = -EINVAL;
                        kfree_skb(skb);
                        goto out_node;
                }

                /* control messages already require the type as 'command' */
                skb_copy_bits(skb, 0, &qrtr_type, 4);
        }

        type = le32_to_cpu(qrtr_type);
        rc = enqueue_fn(node, skb, type, &ipc->us, addr);
        if (rc >= 0)
                rc = len;

out_node:
        qrtr_node_release(node);
        release_sock(sk);

        return rc;
}

static int qrtr_send_resume_tx(struct qrtr_cb *cb)
{
        struct sockaddr_qrtr remote = { AF_QIPCRTR, cb->src_node, cb->src_port };
        struct sockaddr_qrtr local = { AF_QIPCRTR, cb->dst_node, cb->dst_port };
        struct qrtr_ctrl_pkt *pkt;
        struct qrtr_node *node;
        struct sk_buff *skb;
        int ret;

        node = qrtr_node_lookup(remote.sq_node);
        if (!node)
                return -EINVAL;

        skb = qrtr_alloc_ctrl_packet(&pkt, GFP_KERNEL);
        if (!skb)
                return -ENOMEM;

        pkt->cmd = cpu_to_le32(QRTR_TYPE_RESUME_TX);
        pkt->client.node = cpu_to_le32(cb->dst_node);
        pkt->client.port = cpu_to_le32(cb->dst_port);

        ret = qrtr_node_enqueue(node, skb, QRTR_TYPE_RESUME_TX, &local, &remote);

        qrtr_node_release(node);

        return ret;
}

static int qrtr_recvmsg(struct socket *sock, struct msghdr *msg,
                        size_t size, int flags)
{
        DECLARE_SOCKADDR(struct sockaddr_qrtr *, addr, msg->msg_name);
        struct sock *sk = sock->sk;
        struct sk_buff *skb;
        struct qrtr_cb *cb;
        int copied, rc;

        lock_sock(sk);

        if (sock_flag(sk, SOCK_ZAPPED)) {
                release_sock(sk);
                return -EADDRNOTAVAIL;
        }

        skb = skb_recv_datagram(sk, flags, &rc);
        if (!skb) {
                release_sock(sk);
                return rc;
        }
        cb = (struct qrtr_cb *)skb->cb;

        copied = skb->len;
        if (copied > size) {
                copied = size;
                msg->msg_flags |= MSG_TRUNC;
        }

        rc = skb_copy_datagram_msg(skb, 0, msg, copied);
        if (rc < 0)
                goto out;
        rc = copied;

        if (addr) {
                /* There is an anonymous 2-byte hole after sq_family,
                 * make sure to clear it.
                 */
                memset(addr, 0, sizeof(*addr));

                addr->sq_family = AF_QIPCRTR;
                addr->sq_node = cb->src_node;
                addr->sq_port = cb->src_port;
                msg->msg_namelen = sizeof(*addr);
        }

out:
        if (cb->confirm_rx)
                qrtr_send_resume_tx(cb);

        skb_free_datagram(sk, skb);
        release_sock(sk);

        return rc;
}

static int qrtr_connect(struct socket *sock, struct sockaddr_unsized *saddr,
                        int len, int flags)
{
        DECLARE_SOCKADDR(struct sockaddr_qrtr *, addr, saddr);
        struct qrtr_sock *ipc = qrtr_sk(sock->sk);
        struct sock *sk = sock->sk;
        int rc;

        if (len < sizeof(*addr) || addr->sq_family != AF_QIPCRTR)
                return -EINVAL;

        lock_sock(sk);

        sk->sk_state = TCP_CLOSE;
        sock->state = SS_UNCONNECTED;

        rc = qrtr_autobind(sock);
        if (rc) {
                release_sock(sk);
                return rc;
        }

        ipc->peer = *addr;
        sock->state = SS_CONNECTED;
        sk->sk_state = TCP_ESTABLISHED;

        release_sock(sk);

        return 0;
}

static int qrtr_getname(struct socket *sock, struct sockaddr *saddr,
                        int peer)
{
        struct qrtr_sock *ipc = qrtr_sk(sock->sk);
        struct sockaddr_qrtr qaddr;
        struct sock *sk = sock->sk;

        lock_sock(sk);
        if (peer) {
                if (sk->sk_state != TCP_ESTABLISHED) {
                        release_sock(sk);
                        return -ENOTCONN;
                }

                qaddr = ipc->peer;
        } else {
                qaddr = ipc->us;
        }
        release_sock(sk);

        qaddr.sq_family = AF_QIPCRTR;

        memcpy(saddr, &qaddr, sizeof(qaddr));

        return sizeof(qaddr);
}

static int qrtr_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        struct qrtr_sock *ipc = qrtr_sk(sock->sk);
        struct sock *sk = sock->sk;
        struct sockaddr_qrtr *sq;
        struct sk_buff *skb;
        struct ifreq ifr;
        long len = 0;
        int rc = 0;

        lock_sock(sk);

        switch (cmd) {
        case TIOCOUTQ:
                len = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
                if (len < 0)
                        len = 0;
                rc = put_user(len, (int __user *)argp);
                break;
        case TIOCINQ:
                skb = skb_peek(&sk->sk_receive_queue);
                if (skb)
                        len = skb->len;
                rc = put_user(len, (int __user *)argp);
                break;
        case SIOCGIFADDR:
                if (get_user_ifreq(&ifr, NULL, argp)) {
                        rc = -EFAULT;
                        break;
                }

                sq = (struct sockaddr_qrtr *)&ifr.ifr_addr;
                *sq = ipc->us;
                if (put_user_ifreq(&ifr, argp)) {
                        rc = -EFAULT;
                        break;
                }
                break;
        case SIOCADDRT:
        case SIOCDELRT:
        case SIOCSIFADDR:
        case SIOCGIFDSTADDR:
        case SIOCSIFDSTADDR:
        case SIOCGIFBRDADDR:
        case SIOCSIFBRDADDR:
        case SIOCGIFNETMASK:
        case SIOCSIFNETMASK:
                rc = -EINVAL;
                break;
        default:
                rc = -ENOIOCTLCMD;
                break;
        }

        release_sock(sk);

        return rc;
}

static int qrtr_release(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct qrtr_sock *ipc;

        if (!sk)
                return 0;

        lock_sock(sk);

        ipc = qrtr_sk(sk);
        sk->sk_shutdown = SHUTDOWN_MASK;
        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_state_change(sk);

        sock_set_flag(sk, SOCK_DEAD);
        sock_orphan(sk);
        sock->sk = NULL;

        if (!sock_flag(sk, SOCK_ZAPPED))
                qrtr_port_remove(ipc);

        skb_queue_purge(&sk->sk_receive_queue);

        release_sock(sk);
        sock_put(sk);

        return 0;
}

static const struct proto_ops qrtr_proto_ops = {
        .owner          = THIS_MODULE,
        .family         = AF_QIPCRTR,
        .bind           = qrtr_bind,
        .connect        = qrtr_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = sock_no_accept,
        .listen         = sock_no_listen,
        .sendmsg        = qrtr_sendmsg,
        .recvmsg        = qrtr_recvmsg,
        .getname        = qrtr_getname,
        .ioctl          = qrtr_ioctl,
        .gettstamp      = sock_gettstamp,
        .poll           = datagram_poll,
        .shutdown       = sock_no_shutdown,
        .release        = qrtr_release,
        .mmap           = sock_no_mmap,
};

static struct proto qrtr_proto = {
        .name           = "QIPCRTR",
        .owner          = THIS_MODULE,
        .obj_size       = sizeof(struct qrtr_sock),
};

static int qrtr_create(struct net *net, struct socket *sock,
                       int protocol, int kern)
{
        struct qrtr_sock *ipc;
        struct sock *sk;

        if (sock->type != SOCK_DGRAM)
                return -EPROTOTYPE;

        sk = sk_alloc(net, AF_QIPCRTR, GFP_KERNEL, &qrtr_proto, kern);
        if (!sk)
                return -ENOMEM;

        sock_set_flag(sk, SOCK_ZAPPED);

        sock_init_data(sock, sk);
        sock->ops = &qrtr_proto_ops;

        ipc = qrtr_sk(sk);
        ipc->us.sq_family = AF_QIPCRTR;
        ipc->us.sq_node = qrtr_local_nid;
        ipc->us.sq_port = 0;

        return 0;
}

static const struct net_proto_family qrtr_family = {
        .owner  = THIS_MODULE,
        .family = AF_QIPCRTR,
        .create = qrtr_create,
};

static int __init qrtr_proto_init(void)
{
        int rc;

        rc = proto_register(&qrtr_proto, 1);
        if (rc)
                return rc;

        rc = sock_register(&qrtr_family);
        if (rc)
                goto err_proto;

        rc = qrtr_ns_init();
        if (rc)
                goto err_sock;

        return 0;

err_sock:
        sock_unregister(qrtr_family.family);
err_proto:
        proto_unregister(&qrtr_proto);
        return rc;
}
postcore_initcall(qrtr_proto_init);

static void __exit qrtr_proto_fini(void)
{
        qrtr_ns_remove();
        sock_unregister(qrtr_family.family);
        proto_unregister(&qrtr_proto);
}
module_exit(qrtr_proto_fini);

MODULE_DESCRIPTION("Qualcomm IPC-router driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_NETPROTO(PF_QIPCRTR);