// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/net.h>
#include <linux/compat.h>
#include <net/compat.h>
#include <linux/io_uring.h>

#include <uapi/linux/io_uring.h>

#include "filetable.h"
#include "io_uring.h"
#include "kbuf.h"
#include "alloc_cache.h"
#include "net.h"
#include "notif.h"
#include "rsrc.h"
#include "zcrx.h"

struct io_shutdown {
        struct file                     *file;
        int                             how;
};

struct io_accept {
        struct file                     *file;
        struct sockaddr __user          *addr;
        int __user                      *addr_len;
        int                             flags;
        int                             iou_flags;
        u32                             file_slot;
        unsigned long                   nofile;
};

struct io_socket {
        struct file                     *file;
        int                             domain;
        int                             type;
        int                             protocol;
        int                             flags;
        u32                             file_slot;
        unsigned long                   nofile;
};

struct io_connect {
        struct file                     *file;
        struct sockaddr __user          *addr;
        int                             addr_len;
        bool                            in_progress;
        bool                            seen_econnaborted;
};

struct io_bind {
        struct file                     *file;
        int                             addr_len;
};

struct io_listen {
        struct file                     *file;
        int                             backlog;
};

struct io_sr_msg {
        struct file                     *file;
        union {
                struct compat_msghdr __user     *umsg_compat;
                struct user_msghdr __user       *umsg;
                void __user                     *buf;
        };
        int                             len;
        unsigned                        done_io;
        unsigned                        msg_flags;
        unsigned                        nr_multishot_loops;
        u16                             flags;
        /* initialised and used only by !msg send variants */
        u16                             buf_group;
        /* per-invocation mshot limit */
        unsigned                        mshot_len;
        /* overall mshot byte limit */
        unsigned                        mshot_total_len;
        void __user                     *msg_control;
        /* used only for send zerocopy */
        struct io_kiocb                 *notif;
};

/*
 * The UAPI flags are the lower 8 bits, as that's all sqe->ioprio will hold
 * anyway. Use the upper 8 bits for internal uses.
 */
enum sr_retry_flags {
        IORING_RECV_RETRY       = (1U << 15),
        IORING_RECV_PARTIAL_MAP = (1U << 14),
        IORING_RECV_MSHOT_CAP   = (1U << 13),
        IORING_RECV_MSHOT_LIM   = (1U << 12),
        IORING_RECV_MSHOT_DONE  = (1U << 11),

        IORING_RECV_RETRY_CLEAR = IORING_RECV_RETRY | IORING_RECV_PARTIAL_MAP,
        IORING_RECV_NO_RETRY    = IORING_RECV_RETRY | IORING_RECV_PARTIAL_MAP |
                                  IORING_RECV_MSHOT_CAP | IORING_RECV_MSHOT_DONE,
};

/*
 * Number of times we'll try and do receives if there's more data. If we
 * exceed this limit, then add us to the back of the queue and retry from
 * there. This helps fairness between flooding clients.
 */
#define MULTISHOT_MAX_RETRY     32

struct io_recvzc {
        struct file                     *file;
        u16                             flags;
        u32                             len;
        struct io_zcrx_ifq              *ifq;
};

static int io_sg_from_iter_iovec(struct sk_buff *skb,
                                 struct iov_iter *from, size_t length);
static int io_sg_from_iter(struct sk_buff *skb,
                           struct iov_iter *from, size_t length);

int io_shutdown_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_shutdown *shutdown = io_kiocb_to_cmd(req, struct io_shutdown);

        if (unlikely(sqe->off || sqe->addr || sqe->rw_flags ||
                     sqe->buf_index || sqe->splice_fd_in))
                return -EINVAL;

        shutdown->how = READ_ONCE(sqe->len);
        req->flags |= REQ_F_FORCE_ASYNC;
        return 0;
}

int io_shutdown(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_shutdown *shutdown = io_kiocb_to_cmd(req, struct io_shutdown);
        struct socket *sock;
        int ret;

        WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK);

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        ret = __sys_shutdown_sock(sock, shutdown->how);
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}

static bool io_net_retry(struct socket *sock, int flags)
{
        if (!(flags & MSG_WAITALL))
                return false;
        return sock->type == SOCK_STREAM || sock->type == SOCK_SEQPACKET;
}

static void io_netmsg_iovec_free(struct io_async_msghdr *kmsg)
{
        if (kmsg->vec.iovec)
                io_vec_free(&kmsg->vec);
}

static void io_netmsg_recycle(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_async_msghdr *hdr = req->async_data;

        /* can't recycle, ensure we free the iovec if we have one */
        if (unlikely(issue_flags & IO_URING_F_UNLOCKED)) {
                io_netmsg_iovec_free(hdr);
                return;
        }

        /* Let normal cleanup path reap it if we fail adding to the cache */
        io_alloc_cache_vec_kasan(&hdr->vec);
        if (hdr->vec.nr > IO_VEC_CACHE_SOFT_CAP)
                io_vec_free(&hdr->vec);

        if (io_alloc_cache_put(&req->ctx->netmsg_cache, hdr))
                io_req_async_data_clear(req, REQ_F_NEED_CLEANUP);
}

static struct io_async_msghdr *io_msg_alloc_async(struct io_kiocb *req)
{
        struct io_ring_ctx *ctx = req->ctx;
        struct io_async_msghdr *hdr;

        hdr = io_uring_alloc_async_data(&ctx->netmsg_cache, req);
        if (!hdr)
                return NULL;

        /* If the async data was cached, we might have an iov cached inside. */
        if (hdr->vec.iovec)
                req->flags |= REQ_F_NEED_CLEANUP;
        return hdr;
}

static inline void io_mshot_prep_retry(struct io_kiocb *req,
                                       struct io_async_msghdr *kmsg)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);

        req->flags &= ~REQ_F_BL_EMPTY;
        sr->done_io = 0;
        sr->flags &= ~IORING_RECV_RETRY_CLEAR;
        sr->len = sr->mshot_len;
}

static int io_net_import_vec(struct io_kiocb *req, struct io_async_msghdr *iomsg,
                             const struct iovec __user *uiov, unsigned uvec_seg,
                             int ddir)
{
        struct iovec *iov;
        int ret, nr_segs;

        if (iomsg->vec.iovec) {
                nr_segs = iomsg->vec.nr;
                iov = iomsg->vec.iovec;
        } else {
                nr_segs = 1;
                iov = &iomsg->fast_iov;
        }

        ret = __import_iovec(ddir, uiov, uvec_seg, nr_segs, &iov,
                             &iomsg->msg.msg_iter, io_is_compat(req->ctx));
        if (unlikely(ret < 0))
                return ret;

        if (iov) {
                req->flags |= REQ_F_NEED_CLEANUP;
                io_vec_reset_iovec(&iomsg->vec, iov, iomsg->msg.msg_iter.nr_segs);
        }
        return 0;
}

static int io_compat_msg_copy_hdr(struct io_kiocb *req,
                                  struct io_async_msghdr *iomsg,
                                  struct compat_msghdr *msg, int ddir,
                                  struct sockaddr __user **save_addr)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct compat_iovec __user *uiov;
        int ret;

        if (copy_from_user(msg, sr->umsg_compat, sizeof(*msg)))
                return -EFAULT;

        ret = __get_compat_msghdr(&iomsg->msg, msg, save_addr);
        if (ret)
                return ret;

        uiov = compat_ptr(msg->msg_iov);
        if (req->flags & REQ_F_BUFFER_SELECT) {
                if (msg->msg_iovlen == 0) {
                        sr->len = 0;
                } else if (msg->msg_iovlen > 1) {
                        return -EINVAL;
                } else {
                        struct compat_iovec tmp_iov;

                        if (copy_from_user(&tmp_iov, uiov, sizeof(tmp_iov)))
                                return -EFAULT;
                        sr->len = tmp_iov.iov_len;
                }
        }
        return 0;
}

static int io_copy_msghdr_from_user(struct user_msghdr *msg,
                                    struct user_msghdr __user *umsg)
{
        if (!user_access_begin(umsg, sizeof(*umsg)))
                return -EFAULT;
        unsafe_get_user(msg->msg_name, &umsg->msg_name, ua_end);
        unsafe_get_user(msg->msg_namelen, &umsg->msg_namelen, ua_end);
        unsafe_get_user(msg->msg_iov, &umsg->msg_iov, ua_end);
        unsafe_get_user(msg->msg_iovlen, &umsg->msg_iovlen, ua_end);
        unsafe_get_user(msg->msg_control, &umsg->msg_control, ua_end);
        unsafe_get_user(msg->msg_controllen, &umsg->msg_controllen, ua_end);
        user_access_end();
        return 0;
ua_end:
        user_access_end();
        return -EFAULT;
}

static int io_msg_copy_hdr(struct io_kiocb *req, struct io_async_msghdr *iomsg,
                           struct user_msghdr *msg, int ddir,
                           struct sockaddr __user **save_addr)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct user_msghdr __user *umsg = sr->umsg;
        int ret;

        iomsg->msg.msg_name = &iomsg->addr;
        iomsg->msg.msg_iter.nr_segs = 0;

        if (io_is_compat(req->ctx)) {
                struct compat_msghdr cmsg;

                ret = io_compat_msg_copy_hdr(req, iomsg, &cmsg, ddir, save_addr);
                if (ret)
                        return ret;

                memset(msg, 0, sizeof(*msg));
                msg->msg_namelen = cmsg.msg_namelen;
                msg->msg_controllen = cmsg.msg_controllen;
                msg->msg_iov = compat_ptr(cmsg.msg_iov);
                msg->msg_iovlen = cmsg.msg_iovlen;
                return 0;
        }

        ret = io_copy_msghdr_from_user(msg, umsg);
        if (unlikely(ret))
                return ret;

        msg->msg_flags = 0;

        ret = __copy_msghdr(&iomsg->msg, msg, save_addr);
        if (ret)
                return ret;

        if (req->flags & REQ_F_BUFFER_SELECT) {
                if (msg->msg_iovlen == 0) {
                        sr->len = 0;
                } else if (msg->msg_iovlen > 1) {
                        return -EINVAL;
                } else {
                        struct iovec __user *uiov = msg->msg_iov;
                        struct iovec tmp_iov;

                        if (copy_from_user(&tmp_iov, uiov, sizeof(tmp_iov)))
                                return -EFAULT;
                        sr->len = tmp_iov.iov_len;
                }
        }
        return 0;
}

void io_sendmsg_recvmsg_cleanup(struct io_kiocb *req)
{
        struct io_async_msghdr *io = req->async_data;

        io_netmsg_iovec_free(io);
}

static int io_send_setup(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        void __user *addr;
        u16 addr_len;
        int ret;

        sr->buf = u64_to_user_ptr(READ_ONCE(sqe->addr));

        if (READ_ONCE(sqe->__pad3[0]))
                return -EINVAL;

        kmsg->msg.msg_name = NULL;
        kmsg->msg.msg_namelen = 0;
        kmsg->msg.msg_control = NULL;
        kmsg->msg.msg_controllen = 0;
        kmsg->msg.msg_ubuf = NULL;

        addr = u64_to_user_ptr(READ_ONCE(sqe->addr2));
        addr_len = READ_ONCE(sqe->addr_len);
        if (addr) {
                ret = move_addr_to_kernel(addr, addr_len, &kmsg->addr);
                if (unlikely(ret < 0))
                        return ret;
                kmsg->msg.msg_name = &kmsg->addr;
                kmsg->msg.msg_namelen = addr_len;
        }
        if (sr->flags & IORING_RECVSEND_FIXED_BUF) {
                if (sr->flags & IORING_SEND_VECTORIZED)
                        return -EINVAL;
                req->flags |= REQ_F_IMPORT_BUFFER;
                return 0;
        }
        if (req->flags & REQ_F_BUFFER_SELECT)
                return 0;

        if (sr->flags & IORING_SEND_VECTORIZED)
                return io_net_import_vec(req, kmsg, sr->buf, sr->len, ITER_SOURCE);

        return import_ubuf(ITER_SOURCE, sr->buf, sr->len, &kmsg->msg.msg_iter);
}

static int io_sendmsg_setup(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct user_msghdr msg;
        int ret;

        sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
        ret = io_msg_copy_hdr(req, kmsg, &msg, ITER_SOURCE, NULL);
        if (unlikely(ret))
                return ret;
        /* save msg_control as sys_sendmsg() overwrites it */
        sr->msg_control = kmsg->msg.msg_control_user;

        if (sr->flags & IORING_RECVSEND_FIXED_BUF) {
                kmsg->msg.msg_iter.nr_segs = msg.msg_iovlen;
                return io_prep_reg_iovec(req, &kmsg->vec, msg.msg_iov,
                                         msg.msg_iovlen);
        }
        if (req->flags & REQ_F_BUFFER_SELECT)
                return 0;
        return io_net_import_vec(req, kmsg, msg.msg_iov, msg.msg_iovlen, ITER_SOURCE);
}

#define SENDMSG_FLAGS (IORING_RECVSEND_POLL_FIRST | IORING_RECVSEND_BUNDLE | IORING_SEND_VECTORIZED)

int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);

        sr->done_io = 0;
        sr->len = READ_ONCE(sqe->len);
        if (unlikely(sr->len < 0))
                return -EINVAL;
        sr->flags = READ_ONCE(sqe->ioprio);
        if (sr->flags & ~SENDMSG_FLAGS)
                return -EINVAL;
        sr->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL;
        if (sr->msg_flags & MSG_DONTWAIT)
                req->flags |= REQ_F_NOWAIT;
        if (req->flags & REQ_F_BUFFER_SELECT)
                sr->buf_group = req->buf_index;
        if (sr->flags & IORING_RECVSEND_BUNDLE) {
                if (req->opcode == IORING_OP_SENDMSG)
                        return -EINVAL;
                sr->msg_flags |= MSG_WAITALL;
                req->flags |= REQ_F_MULTISHOT;
        }

        if (io_is_compat(req->ctx))
                sr->msg_flags |= MSG_CMSG_COMPAT;

        if (unlikely(!io_msg_alloc_async(req)))
                return -ENOMEM;
        if (req->opcode != IORING_OP_SENDMSG)
                return io_send_setup(req, sqe);
        if (unlikely(sqe->addr2 || sqe->file_index))
                return -EINVAL;
        return io_sendmsg_setup(req, sqe);
}

static void io_req_msg_cleanup(struct io_kiocb *req,
                               unsigned int issue_flags)
{
        io_netmsg_recycle(req, issue_flags);
}

/*
 * For bundle completions, we need to figure out how many segments we consumed.
 * A bundle could be using a single ITER_UBUF if that's all we mapped, or it
 * could be using an ITER_IOVEC. If the latter, then if we consumed all of
 * the segments, then it's a trivial questiont o answer. If we have residual
 * data in the iter, then loop the segments to figure out how much we
 * transferred.
 */
static int io_bundle_nbufs(struct io_async_msghdr *kmsg, int ret)
{
        struct iovec *iov;
        int nbufs;

        /* no data is always zero segments, and a ubuf is always 1 segment */
        if (ret <= 0)
                return 0;
        if (iter_is_ubuf(&kmsg->msg.msg_iter))
                return 1;

        iov = kmsg->vec.iovec;
        if (!iov)
                iov = &kmsg->fast_iov;

        /* if all data was transferred, it's basic pointer math */
        if (!iov_iter_count(&kmsg->msg.msg_iter))
                return iter_iov(&kmsg->msg.msg_iter) - iov;

        /* short transfer, count segments */
        nbufs = 0;
        do {
                int this_len = min_t(int, iov[nbufs].iov_len, ret);

                nbufs++;
                ret -= this_len;
        } while (ret);

        return nbufs;
}

static int io_net_kbuf_recyle(struct io_kiocb *req, struct io_buffer_list *bl,
                              struct io_async_msghdr *kmsg, int len)
{
        req->flags |= REQ_F_BL_NO_RECYCLE;
        if (req->flags & REQ_F_BUFFERS_COMMIT)
                io_kbuf_commit(req, bl, len, io_bundle_nbufs(kmsg, len));
        return IOU_RETRY;
}

static inline bool io_send_finish(struct io_kiocb *req,
                                  struct io_async_msghdr *kmsg,
                                  struct io_br_sel *sel)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        bool bundle_finished = sel->val <= 0;
        unsigned int cflags;

        if (!(sr->flags & IORING_RECVSEND_BUNDLE)) {
                cflags = io_put_kbuf(req, sel->val, sel->buf_list);
                goto finish;
        }

        cflags = io_put_kbufs(req, sel->val, sel->buf_list, io_bundle_nbufs(kmsg, sel->val));

        /*
         * Don't start new bundles if the buffer list is empty, or if the
         * current operation needed to go through polling to complete.
         */
        if (bundle_finished || req->flags & (REQ_F_BL_EMPTY | REQ_F_POLLED))
                goto finish;

        /*
         * Fill CQE for this receive and see if we should keep trying to
         * receive from this socket.
         */
        if (io_req_post_cqe(req, sel->val, cflags | IORING_CQE_F_MORE)) {
                io_mshot_prep_retry(req, kmsg);
                return false;
        }

        /* Otherwise stop bundle and use the current result. */
finish:
        io_req_set_res(req, sel->val, cflags);
        sel->val = IOU_COMPLETE;
        return true;
}

int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct socket *sock;
        unsigned flags;
        int min_ret = 0;
        int ret;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        if (!(req->flags & REQ_F_POLLED) &&
            (sr->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        flags = sr->msg_flags;
        if (issue_flags & IO_URING_F_NONBLOCK)
                flags |= MSG_DONTWAIT;
        if (flags & MSG_WAITALL)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);

        kmsg->msg.msg_control_user = sr->msg_control;

        ret = __sys_sendmsg_sock(sock, &kmsg->msg, flags);

        if (ret < min_ret) {
                if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
                        return -EAGAIN;
                if (ret > 0 && io_net_retry(sock, flags)) {
                        kmsg->msg.msg_controllen = 0;
                        kmsg->msg.msg_control = NULL;
                        sr->done_io += ret;
                        return -EAGAIN;
                }
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        }
        io_req_msg_cleanup(req, issue_flags);
        if (ret >= 0)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}

static int io_send_select_buffer(struct io_kiocb *req, unsigned int issue_flags,
                                 struct io_br_sel *sel, struct io_async_msghdr *kmsg)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct buf_sel_arg arg = {
                .iovs = &kmsg->fast_iov,
                .max_len = min_not_zero(sr->len, INT_MAX),
                .nr_iovs = 1,
                .buf_group = sr->buf_group,
        };
        int ret;

        if (kmsg->vec.iovec) {
                arg.nr_iovs = kmsg->vec.nr;
                arg.iovs = kmsg->vec.iovec;
                arg.mode = KBUF_MODE_FREE;
        }

        if (!(sr->flags & IORING_RECVSEND_BUNDLE))
                arg.nr_iovs = 1;
        else
                arg.mode |= KBUF_MODE_EXPAND;

        ret = io_buffers_select(req, &arg, sel, issue_flags);
        if (unlikely(ret < 0))
                return ret;

        if (arg.iovs != &kmsg->fast_iov && arg.iovs != kmsg->vec.iovec) {
                kmsg->vec.nr = ret;
                kmsg->vec.iovec = arg.iovs;
                req->flags |= REQ_F_NEED_CLEANUP;
        }
        sr->len = arg.out_len;

        if (ret == 1) {
                sr->buf = arg.iovs[0].iov_base;
                ret = import_ubuf(ITER_SOURCE, sr->buf, sr->len,
                                        &kmsg->msg.msg_iter);
                if (unlikely(ret))
                        return ret;
        } else {
                iov_iter_init(&kmsg->msg.msg_iter, ITER_SOURCE,
                                arg.iovs, ret, arg.out_len);
        }

        return 0;
}

int io_send(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct io_br_sel sel = { };
        struct socket *sock;
        unsigned flags;
        int min_ret = 0;
        int ret;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        if (!(req->flags & REQ_F_POLLED) &&
            (sr->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        flags = sr->msg_flags;
        if (issue_flags & IO_URING_F_NONBLOCK)
                flags |= MSG_DONTWAIT;

retry_bundle:
        sel.buf_list = NULL;
        if (io_do_buffer_select(req)) {
                ret = io_send_select_buffer(req, issue_flags, &sel, kmsg);
                if (ret)
                        return ret;
        }

        /*
         * If MSG_WAITALL is set, or this is a bundle send, then we need
         * the full amount. If just bundle is set, if we do a short send
         * then we complete the bundle sequence rather than continue on.
         */
        if (flags & MSG_WAITALL || sr->flags & IORING_RECVSEND_BUNDLE)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);

        flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
        kmsg->msg.msg_flags = flags;
        ret = sock_sendmsg(sock, &kmsg->msg);
        if (ret < min_ret) {
                if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
                        return -EAGAIN;

                if (ret > 0 && io_net_retry(sock, flags)) {
                        sr->len -= ret;
                        sr->buf += ret;
                        sr->done_io += ret;
                        return io_net_kbuf_recyle(req, sel.buf_list, kmsg, ret);
                }
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        }
        if (ret >= 0)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;

        sel.val = ret;
        if (!io_send_finish(req, kmsg, &sel))
                goto retry_bundle;

        io_req_msg_cleanup(req, issue_flags);
        return sel.val;
}

static int io_recvmsg_mshot_prep(struct io_kiocb *req,
                                 struct io_async_msghdr *iomsg,
                                 int namelen, size_t controllen)
{
        if ((req->flags & (REQ_F_APOLL_MULTISHOT|REQ_F_BUFFER_SELECT)) ==
                          (REQ_F_APOLL_MULTISHOT|REQ_F_BUFFER_SELECT)) {
                int hdr;

                if (unlikely(namelen < 0))
                        return -EOVERFLOW;
                if (check_add_overflow(sizeof(struct io_uring_recvmsg_out),
                                        namelen, &hdr))
                        return -EOVERFLOW;
                if (check_add_overflow(hdr, controllen, &hdr))
                        return -EOVERFLOW;

                iomsg->namelen = namelen;
                iomsg->controllen = controllen;
                return 0;
        }

        return 0;
}

static int io_recvmsg_copy_hdr(struct io_kiocb *req,
                               struct io_async_msghdr *iomsg)
{
        struct user_msghdr msg;
        int ret;

        ret = io_msg_copy_hdr(req, iomsg, &msg, ITER_DEST, &iomsg->uaddr);
        if (unlikely(ret))
                return ret;

        if (!(req->flags & REQ_F_BUFFER_SELECT)) {
                ret = io_net_import_vec(req, iomsg, msg.msg_iov, msg.msg_iovlen,
                                        ITER_DEST);
                if (unlikely(ret))
                        return ret;
        }
        return io_recvmsg_mshot_prep(req, iomsg, msg.msg_namelen,
                                        msg.msg_controllen);
}

static int io_recvmsg_prep_setup(struct io_kiocb *req)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg;

        kmsg = io_msg_alloc_async(req);
        if (unlikely(!kmsg))
                return -ENOMEM;

        if (req->opcode == IORING_OP_RECV) {
                kmsg->msg.msg_name = NULL;
                kmsg->msg.msg_namelen = 0;
                kmsg->msg.msg_inq = 0;
                kmsg->msg.msg_control = NULL;
                kmsg->msg.msg_get_inq = 1;
                kmsg->msg.msg_controllen = 0;
                kmsg->msg.msg_iocb = NULL;
                kmsg->msg.msg_ubuf = NULL;

                if (req->flags & REQ_F_BUFFER_SELECT)
                        return 0;
                return import_ubuf(ITER_DEST, sr->buf, sr->len,
                                   &kmsg->msg.msg_iter);
        }

        return io_recvmsg_copy_hdr(req, kmsg);
}

#define RECVMSG_FLAGS (IORING_RECVSEND_POLL_FIRST | IORING_RECV_MULTISHOT | \
                        IORING_RECVSEND_BUNDLE)

int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);

        sr->done_io = 0;

        if (unlikely(sqe->addr2))
                return -EINVAL;

        sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
        sr->len = READ_ONCE(sqe->len);
        if (unlikely(sr->len < 0))
                return -EINVAL;
        sr->flags = READ_ONCE(sqe->ioprio);
        if (sr->flags & ~RECVMSG_FLAGS)
                return -EINVAL;
        sr->msg_flags = READ_ONCE(sqe->msg_flags);
        if (sr->msg_flags & MSG_DONTWAIT)
                req->flags |= REQ_F_NOWAIT;
        if (sr->msg_flags & MSG_ERRQUEUE)
                req->flags |= REQ_F_CLEAR_POLLIN;
        if (req->flags & REQ_F_BUFFER_SELECT)
                sr->buf_group = req->buf_index;
        sr->mshot_total_len = sr->mshot_len = 0;
        if (sr->flags & IORING_RECV_MULTISHOT) {
                if (!(req->flags & REQ_F_BUFFER_SELECT))
                        return -EINVAL;
                if (sr->msg_flags & MSG_WAITALL)
                        return -EINVAL;
                if (req->opcode == IORING_OP_RECV) {
                        sr->mshot_len = sr->len;
                        sr->mshot_total_len = READ_ONCE(sqe->optlen);
                        if (sr->mshot_total_len)
                                sr->flags |= IORING_RECV_MSHOT_LIM;
                } else if (sqe->optlen) {
                        return -EINVAL;
                }
                req->flags |= REQ_F_APOLL_MULTISHOT;
        } else if (sqe->optlen) {
                return -EINVAL;
        }

        if (sr->flags & IORING_RECVSEND_BUNDLE) {
                if (req->opcode == IORING_OP_RECVMSG)
                        return -EINVAL;
        }

        if (io_is_compat(req->ctx))
                sr->msg_flags |= MSG_CMSG_COMPAT;

        sr->nr_multishot_loops = 0;
        return io_recvmsg_prep_setup(req);
}

/* bits to clear in old and inherit in new cflags on bundle retry */
#define CQE_F_MASK      (IORING_CQE_F_SOCK_NONEMPTY|IORING_CQE_F_MORE)

/*
 * Finishes io_recv and io_recvmsg.
 *
 * Returns true if it is actually finished, or false if it should run
 * again (for multishot).
 */
static inline bool io_recv_finish(struct io_kiocb *req,
                                  struct io_async_msghdr *kmsg,
                                  struct io_br_sel *sel, bool mshot_finished,
                                  unsigned issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        unsigned int cflags = 0;

        if (kmsg->msg.msg_inq > 0)
                cflags |= IORING_CQE_F_SOCK_NONEMPTY;

        if (sel->val > 0 && sr->flags & IORING_RECV_MSHOT_LIM) {
                /*
                 * If sr->len hits zero, the limit has been reached. Mark
                 * mshot as finished, and flag MSHOT_DONE as well to prevent
                 * a potential bundle from being retried.
                 */
                sr->mshot_total_len -= min_t(int, sel->val, sr->mshot_total_len);
                if (!sr->mshot_total_len) {
                        sr->flags |= IORING_RECV_MSHOT_DONE;
                        mshot_finished = true;
                }
        }

        if (sr->flags & IORING_RECVSEND_BUNDLE) {
                size_t this_ret = sel->val - sr->done_io;

                cflags |= io_put_kbufs(req, this_ret, sel->buf_list, io_bundle_nbufs(kmsg, this_ret));
                if (sr->flags & IORING_RECV_RETRY)
                        cflags = req->cqe.flags | (cflags & CQE_F_MASK);
                if (sr->mshot_len && sel->val >= sr->mshot_len)
                        sr->flags |= IORING_RECV_MSHOT_CAP;
                /* bundle with no more immediate buffers, we're done */
                if (req->flags & REQ_F_BL_EMPTY)
                        goto finish;
                /*
                 * If more is available AND it was a full transfer, retry and
                 * append to this one
                 */
                if (!(sr->flags & IORING_RECV_NO_RETRY) &&
                    kmsg->msg.msg_inq > 1 && this_ret > 0 &&
                    !iov_iter_count(&kmsg->msg.msg_iter)) {
                        req->cqe.flags = cflags & ~CQE_F_MASK;
                        sr->len = kmsg->msg.msg_inq;
                        sr->done_io += this_ret;
                        sr->flags |= IORING_RECV_RETRY;
                        return false;
                }
        } else {
                cflags |= io_put_kbuf(req, sel->val, sel->buf_list);
        }

        /*
         * Fill CQE for this receive and see if we should keep trying to
         * receive from this socket.
         */
        if ((req->flags & REQ_F_APOLL_MULTISHOT) && !mshot_finished &&
            io_req_post_cqe(req, sel->val, cflags | IORING_CQE_F_MORE)) {
                sel->val = IOU_RETRY;
                io_mshot_prep_retry(req, kmsg);
                /* Known not-empty or unknown state, retry */
                if (cflags & IORING_CQE_F_SOCK_NONEMPTY || kmsg->msg.msg_inq < 0) {
                        if (sr->nr_multishot_loops++ < MULTISHOT_MAX_RETRY &&
                            !(sr->flags & IORING_RECV_MSHOT_CAP)) {
                                return false;
                        }
                        /* mshot retries exceeded, force a requeue */
                        sr->nr_multishot_loops = 0;
                        sr->flags &= ~IORING_RECV_MSHOT_CAP;
                        if (issue_flags & IO_URING_F_MULTISHOT)
                                sel->val = IOU_REQUEUE;
                }
                return true;
        }

        /* Finish the request / stop multishot. */
finish:
        io_req_set_res(req, sel->val, cflags);
        sel->val = IOU_COMPLETE;
        io_req_msg_cleanup(req, issue_flags);
        return true;
}

static int io_recvmsg_prep_multishot(struct io_async_msghdr *kmsg,
                                     struct io_sr_msg *sr, void __user **buf,
                                     size_t *len)
{
        unsigned long ubuf = (unsigned long) *buf;
        unsigned long hdr;

        hdr = sizeof(struct io_uring_recvmsg_out) + kmsg->namelen +
                kmsg->controllen;
        if (*len < hdr)
                return -EFAULT;

        if (kmsg->controllen) {
                unsigned long control = ubuf + hdr - kmsg->controllen;

                kmsg->msg.msg_control_user = (void __user *) control;
                kmsg->msg.msg_controllen = kmsg->controllen;
        }

        sr->buf = *buf; /* stash for later copy */
        *buf = (void __user *) (ubuf + hdr);
        kmsg->payloadlen = *len = *len - hdr;
        return 0;
}

struct io_recvmsg_multishot_hdr {
        struct io_uring_recvmsg_out msg;
        struct sockaddr_storage addr;
};

static int io_recvmsg_multishot(struct socket *sock, struct io_sr_msg *io,
                                struct io_async_msghdr *kmsg,
                                unsigned int flags, bool *finished)
{
        int err;
        int copy_len;
        struct io_recvmsg_multishot_hdr hdr;

        if (kmsg->namelen)
                kmsg->msg.msg_name = &hdr.addr;
        kmsg->msg.msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
        kmsg->msg.msg_namelen = 0;

        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;

        err = sock_recvmsg(sock, &kmsg->msg, flags);
        *finished = err <= 0;
        if (err < 0)
                return err;

        hdr.msg = (struct io_uring_recvmsg_out) {
                .controllen = kmsg->controllen - kmsg->msg.msg_controllen,
                .flags = kmsg->msg.msg_flags & ~MSG_CMSG_COMPAT
        };

        hdr.msg.payloadlen = err;
        if (err > kmsg->payloadlen)
                err = kmsg->payloadlen;

        copy_len = sizeof(struct io_uring_recvmsg_out);
        if (kmsg->msg.msg_namelen > kmsg->namelen)
                copy_len += kmsg->namelen;
        else
                copy_len += kmsg->msg.msg_namelen;

        /*
         *      "fromlen shall refer to the value before truncation.."
         *                      1003.1g
         */
        hdr.msg.namelen = kmsg->msg.msg_namelen;

        /* ensure that there is no gap between hdr and sockaddr_storage */
        BUILD_BUG_ON(offsetof(struct io_recvmsg_multishot_hdr, addr) !=
                     sizeof(struct io_uring_recvmsg_out));
        if (copy_to_user(io->buf, &hdr, copy_len)) {
                *finished = true;
                return -EFAULT;
        }

        return sizeof(struct io_uring_recvmsg_out) + kmsg->namelen +
                        kmsg->controllen + err;
}

int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct io_br_sel sel = { };
        struct socket *sock;
        unsigned flags;
        int ret, min_ret = 0;
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
        bool mshot_finished = true;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        if (!(req->flags & REQ_F_POLLED) &&
            (sr->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        flags = sr->msg_flags;
        if (force_nonblock)
                flags |= MSG_DONTWAIT;

retry_multishot:
        sel.buf_list = NULL;
        if (io_do_buffer_select(req)) {
                size_t len = sr->len;

                sel = io_buffer_select(req, &len, sr->buf_group, issue_flags);
                if (!sel.addr)
                        return -ENOBUFS;

                if (req->flags & REQ_F_APOLL_MULTISHOT) {
                        ret = io_recvmsg_prep_multishot(kmsg, sr, &sel.addr, &len);
                        if (ret) {
                                io_kbuf_recycle(req, sel.buf_list, issue_flags);
                                return ret;
                        }
                }

                iov_iter_ubuf(&kmsg->msg.msg_iter, ITER_DEST, sel.addr, len);
        }

        kmsg->msg.msg_get_inq = 1;
        kmsg->msg.msg_inq = -1;
        if (req->flags & REQ_F_APOLL_MULTISHOT) {
                ret = io_recvmsg_multishot(sock, sr, kmsg, flags,
                                           &mshot_finished);
        } else {
                /* disable partial retry for recvmsg with cmsg attached */
                if (flags & MSG_WAITALL && !kmsg->msg.msg_controllen)
                        min_ret = iov_iter_count(&kmsg->msg.msg_iter);

                ret = __sys_recvmsg_sock(sock, &kmsg->msg, sr->umsg,
                                         kmsg->uaddr, flags);
        }

        if (ret < min_ret) {
                if (ret == -EAGAIN && force_nonblock) {
                        io_kbuf_recycle(req, sel.buf_list, issue_flags);
                        return IOU_RETRY;
                }
                if (ret > 0 && io_net_retry(sock, flags)) {
                        sr->done_io += ret;
                        return io_net_kbuf_recyle(req, sel.buf_list, kmsg, ret);
                }
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        } else if ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
                req_set_fail(req);
        }

        if (ret > 0)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;
        else
                io_kbuf_recycle(req, sel.buf_list, issue_flags);

        sel.val = ret;
        if (!io_recv_finish(req, kmsg, &sel, mshot_finished, issue_flags))
                goto retry_multishot;

        return sel.val;
}

static int io_recv_buf_select(struct io_kiocb *req, struct io_async_msghdr *kmsg,
                              struct io_br_sel *sel, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        int ret;

        /*
         * If the ring isn't locked, then don't use the peek interface
         * to grab multiple buffers as we will lock/unlock between
         * this selection and posting the buffers.
         */
        if (!(issue_flags & IO_URING_F_UNLOCKED) &&
            sr->flags & IORING_RECVSEND_BUNDLE) {
                struct buf_sel_arg arg = {
                        .iovs = &kmsg->fast_iov,
                        .nr_iovs = 1,
                        .mode = KBUF_MODE_EXPAND,
                        .buf_group = sr->buf_group,
                };

                if (kmsg->vec.iovec) {
                        arg.nr_iovs = kmsg->vec.nr;
                        arg.iovs = kmsg->vec.iovec;
                        arg.mode |= KBUF_MODE_FREE;
                }

                if (sel->val)
                        arg.max_len = sel->val;
                else if (kmsg->msg.msg_inq > 1)
                        arg.max_len = min_not_zero(sel->val, (ssize_t) kmsg->msg.msg_inq);

                /* if mshot limited, ensure we don't go over */
                if (sr->flags & IORING_RECV_MSHOT_LIM)
                        arg.max_len = min_not_zero(arg.max_len, sr->mshot_total_len);
                ret = io_buffers_peek(req, &arg, sel);
                if (unlikely(ret < 0))
                        return ret;

                if (arg.iovs != &kmsg->fast_iov && arg.iovs != kmsg->vec.iovec) {
                        kmsg->vec.nr = ret;
                        kmsg->vec.iovec = arg.iovs;
                        req->flags |= REQ_F_NEED_CLEANUP;
                }
                if (arg.partial_map)
                        sr->flags |= IORING_RECV_PARTIAL_MAP;

                /* special case 1 vec, can be a fast path */
                if (ret == 1) {
                        sr->buf = arg.iovs[0].iov_base;
                        sr->len = arg.iovs[0].iov_len;
                        goto map_ubuf;
                }
                iov_iter_init(&kmsg->msg.msg_iter, ITER_DEST, arg.iovs, ret,
                                arg.out_len);
        } else {
                size_t len = sel->val;

                *sel = io_buffer_select(req, &len, sr->buf_group, issue_flags);
                if (!sel->addr)
                        return -ENOBUFS;
                sr->buf = sel->addr;
                sr->len = len;
map_ubuf:
                ret = import_ubuf(ITER_DEST, sr->buf, sr->len,
                                  &kmsg->msg.msg_iter);
                if (unlikely(ret))
                        return ret;
        }

        return 0;
}

int io_recv(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct io_br_sel sel;
        struct socket *sock;
        unsigned flags;
        int ret, min_ret = 0;
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
        bool mshot_finished;

        if (!(req->flags & REQ_F_POLLED) &&
            (sr->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        flags = sr->msg_flags;
        if (force_nonblock)
                flags |= MSG_DONTWAIT;

retry_multishot:
        sel.buf_list = NULL;
        if (io_do_buffer_select(req)) {
                sel.val = sr->len;
                ret = io_recv_buf_select(req, kmsg, &sel, issue_flags);
                if (unlikely(ret < 0)) {
                        kmsg->msg.msg_inq = -1;
                        goto out_free;
                }
                sr->buf = NULL;
        }

        kmsg->msg.msg_flags = 0;
        kmsg->msg.msg_inq = -1;

        if (flags & MSG_WAITALL)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);

        ret = sock_recvmsg(sock, &kmsg->msg, flags);
        if (ret < min_ret) {
                if (ret == -EAGAIN && force_nonblock) {
                        io_kbuf_recycle(req, sel.buf_list, issue_flags);
                        return IOU_RETRY;
                }
                if (ret > 0 && io_net_retry(sock, flags)) {
                        sr->len -= ret;
                        sr->buf += ret;
                        sr->done_io += ret;
                        return io_net_kbuf_recyle(req, sel.buf_list, kmsg, ret);
                }
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        } else if ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
out_free:
                req_set_fail(req);
        }

        mshot_finished = ret <= 0;
        if (ret > 0)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;
        else
                io_kbuf_recycle(req, sel.buf_list, issue_flags);

        sel.val = ret;
        if (!io_recv_finish(req, kmsg, &sel, mshot_finished, issue_flags))
                goto retry_multishot;

        return sel.val;
}

int io_recvzc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_recvzc *zc = io_kiocb_to_cmd(req, struct io_recvzc);
        unsigned ifq_idx;

        if (unlikely(sqe->addr2 || sqe->addr || sqe->addr3))
                return -EINVAL;

        ifq_idx = READ_ONCE(sqe->zcrx_ifq_idx);
        zc->ifq = xa_load(&req->ctx->zcrx_ctxs, ifq_idx);
        if (!zc->ifq)
                return -EINVAL;

        zc->len = READ_ONCE(sqe->len);
        zc->flags = READ_ONCE(sqe->ioprio);
        if (READ_ONCE(sqe->msg_flags))
                return -EINVAL;
        if (zc->flags & ~(IORING_RECVSEND_POLL_FIRST | IORING_RECV_MULTISHOT))
                return -EINVAL;
        /* multishot required */
        if (!(zc->flags & IORING_RECV_MULTISHOT))
                return -EINVAL;
        /* All data completions are posted as aux CQEs. */
        req->flags |= REQ_F_APOLL_MULTISHOT;

        return 0;
}

int io_recvzc(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_recvzc *zc = io_kiocb_to_cmd(req, struct io_recvzc);
        struct socket *sock;
        unsigned int len;
        int ret;

        if (!(req->flags & REQ_F_POLLED) &&
            (zc->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        len = zc->len;
        ret = io_zcrx_recv(req, zc->ifq, sock, 0, issue_flags, &zc->len);
        if (len && zc->len == 0) {
                io_req_set_res(req, 0, 0);

                return IOU_COMPLETE;
        }
        if (unlikely(ret <= 0) && ret != -EAGAIN) {
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                if (ret == IOU_REQUEUE)
                        return IOU_REQUEUE;

                req_set_fail(req);
                io_req_set_res(req, ret, 0);
                return IOU_COMPLETE;
        }
        return IOU_RETRY;
}

void io_send_zc_cleanup(struct io_kiocb *req)
{
        struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *io = req->async_data;

        if (req_has_async_data(req))
                io_netmsg_iovec_free(io);
        if (zc->notif) {
                io_notif_flush(zc->notif);
                zc->notif = NULL;
        }
}

#define IO_ZC_FLAGS_COMMON (IORING_RECVSEND_POLL_FIRST | IORING_RECVSEND_FIXED_BUF)
#define IO_ZC_FLAGS_VALID  (IO_ZC_FLAGS_COMMON | IORING_SEND_ZC_REPORT_USAGE | \
                                IORING_SEND_VECTORIZED)

int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_ring_ctx *ctx = req->ctx;
        struct io_async_msghdr *iomsg;
        struct io_kiocb *notif;
        int ret;

        zc->done_io = 0;

        if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))
                return -EINVAL;
        /* we don't support IOSQE_CQE_SKIP_SUCCESS just yet */
        if (req->flags & REQ_F_CQE_SKIP)
                return -EINVAL;

        notif = zc->notif = io_alloc_notif(ctx);
        if (!notif)
                return -ENOMEM;
        notif->cqe.user_data = req->cqe.user_data;
        notif->cqe.res = 0;
        notif->cqe.flags = IORING_CQE_F_NOTIF;
        req->flags |= REQ_F_NEED_CLEANUP | REQ_F_POLL_NO_LAZY;

        zc->flags = READ_ONCE(sqe->ioprio);
        if (unlikely(zc->flags & ~IO_ZC_FLAGS_COMMON)) {
                if (zc->flags & ~IO_ZC_FLAGS_VALID)
                        return -EINVAL;
                if (zc->flags & IORING_SEND_ZC_REPORT_USAGE) {
                        struct io_notif_data *nd = io_notif_to_data(notif);

                        nd->zc_report = true;
                        nd->zc_used = false;
                        nd->zc_copied = false;
                }
        }

        zc->len = READ_ONCE(sqe->len);
        zc->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL | MSG_ZEROCOPY;
        req->buf_index = READ_ONCE(sqe->buf_index);
        if (zc->msg_flags & MSG_DONTWAIT)
                req->flags |= REQ_F_NOWAIT;

        if (io_is_compat(req->ctx))
                zc->msg_flags |= MSG_CMSG_COMPAT;

        iomsg = io_msg_alloc_async(req);
        if (unlikely(!iomsg))
                return -ENOMEM;

        if (req->opcode == IORING_OP_SEND_ZC) {
                ret = io_send_setup(req, sqe);
        } else {
                if (unlikely(sqe->addr2 || sqe->file_index))
                        return -EINVAL;
                ret = io_sendmsg_setup(req, sqe);
        }
        if (unlikely(ret))
                return ret;

        if (!(zc->flags & IORING_RECVSEND_FIXED_BUF)) {
                iomsg->msg.sg_from_iter = io_sg_from_iter_iovec;
                return io_notif_account_mem(zc->notif, iomsg->msg.msg_iter.count);
        }
        iomsg->msg.sg_from_iter = io_sg_from_iter;
        return 0;
}

static int io_sg_from_iter_iovec(struct sk_buff *skb,
                                 struct iov_iter *from, size_t length)
{
        skb_zcopy_downgrade_managed(skb);
        return zerocopy_fill_skb_from_iter(skb, from, length);
}

static int io_sg_from_iter(struct sk_buff *skb,
                           struct iov_iter *from, size_t length)
{
        struct skb_shared_info *shinfo = skb_shinfo(skb);
        int frag = shinfo->nr_frags;
        int ret = 0;
        struct bvec_iter bi;
        ssize_t copied = 0;
        unsigned long truesize = 0;

        if (!frag)
                shinfo->flags |= SKBFL_MANAGED_FRAG_REFS;
        else if (unlikely(!skb_zcopy_managed(skb)))
                return zerocopy_fill_skb_from_iter(skb, from, length);

        bi.bi_size = min(from->count, length);
        bi.bi_bvec_done = from->iov_offset;
        bi.bi_idx = 0;

        while (bi.bi_size && frag < MAX_SKB_FRAGS) {
                struct bio_vec v = mp_bvec_iter_bvec(from->bvec, bi);

                copied += v.bv_len;
                truesize += PAGE_ALIGN(v.bv_len + v.bv_offset);
                __skb_fill_page_desc_noacc(shinfo, frag++, v.bv_page,
                                           v.bv_offset, v.bv_len);
                bvec_iter_advance_single(from->bvec, &bi, v.bv_len);
        }
        if (bi.bi_size)
                ret = -EMSGSIZE;

        shinfo->nr_frags = frag;
        from->bvec += bi.bi_idx;
        from->nr_segs -= bi.bi_idx;
        from->count -= copied;
        from->iov_offset = bi.bi_bvec_done;

        skb->data_len += copied;
        skb->len += copied;
        skb->truesize += truesize;
        return ret;
}

static int io_send_zc_import(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;

        WARN_ON_ONCE(!(sr->flags & IORING_RECVSEND_FIXED_BUF));

        sr->notif->buf_index = req->buf_index;
        return io_import_reg_buf(sr->notif, &kmsg->msg.msg_iter,
                                (u64)(uintptr_t)sr->buf, sr->len,
                                ITER_SOURCE, issue_flags);
}

int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct socket *sock;
        unsigned msg_flags;
        int ret, min_ret = 0;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;
        if (!test_bit(SOCK_SUPPORT_ZC, &sock->flags))
                return -EOPNOTSUPP;

        if (!(req->flags & REQ_F_POLLED) &&
            (zc->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        if (req->flags & REQ_F_IMPORT_BUFFER) {
                req->flags &= ~REQ_F_IMPORT_BUFFER;
                ret = io_send_zc_import(req, issue_flags);
                if (unlikely(ret))
                        return ret;
        }

        msg_flags = zc->msg_flags;
        if (issue_flags & IO_URING_F_NONBLOCK)
                msg_flags |= MSG_DONTWAIT;
        if (msg_flags & MSG_WAITALL)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);
        msg_flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;

        kmsg->msg.msg_flags = msg_flags;
        kmsg->msg.msg_ubuf = &io_notif_to_data(zc->notif)->uarg;
        ret = sock_sendmsg(sock, &kmsg->msg);

        if (unlikely(ret < min_ret)) {
                if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
                        return -EAGAIN;

                if (ret > 0 && io_net_retry(sock, kmsg->msg.msg_flags)) {
                        zc->done_io += ret;
                        return -EAGAIN;
                }
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        }

        if (ret >= 0)
                ret += zc->done_io;
        else if (zc->done_io)
                ret = zc->done_io;

        /*
         * If we're in io-wq we can't rely on tw ordering guarantees, defer
         * flushing notif to io_send_zc_cleanup()
         */
        if (!(issue_flags & IO_URING_F_UNLOCKED)) {
                io_notif_flush(zc->notif);
                zc->notif = NULL;
                io_req_msg_cleanup(req, 0);
        }
        io_req_set_res(req, ret, IORING_CQE_F_MORE);
        return IOU_COMPLETE;
}

int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
        struct io_async_msghdr *kmsg = req->async_data;
        struct socket *sock;
        unsigned flags;
        int ret, min_ret = 0;

        if (req->flags & REQ_F_IMPORT_BUFFER) {
                unsigned uvec_segs = kmsg->msg.msg_iter.nr_segs;
                int ret;

                sr->notif->buf_index = req->buf_index;
                ret = io_import_reg_vec(ITER_SOURCE, &kmsg->msg.msg_iter,
                                        sr->notif, &kmsg->vec, uvec_segs,
                                        issue_flags);
                if (unlikely(ret))
                        return ret;
                req->flags &= ~REQ_F_IMPORT_BUFFER;
        }

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;
        if (!test_bit(SOCK_SUPPORT_ZC, &sock->flags))
                return -EOPNOTSUPP;

        if (!(req->flags & REQ_F_POLLED) &&
            (sr->flags & IORING_RECVSEND_POLL_FIRST))
                return -EAGAIN;

        flags = sr->msg_flags;
        if (issue_flags & IO_URING_F_NONBLOCK)
                flags |= MSG_DONTWAIT;
        if (flags & MSG_WAITALL)
                min_ret = iov_iter_count(&kmsg->msg.msg_iter);

        kmsg->msg.msg_control_user = sr->msg_control;
        kmsg->msg.msg_ubuf = &io_notif_to_data(sr->notif)->uarg;
        ret = __sys_sendmsg_sock(sock, &kmsg->msg, flags);

        if (unlikely(ret < min_ret)) {
                if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
                        return -EAGAIN;

                if (ret > 0 && io_net_retry(sock, flags)) {
                        sr->done_io += ret;
                        return -EAGAIN;
                }
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        }

        if (ret >= 0)
                ret += sr->done_io;
        else if (sr->done_io)
                ret = sr->done_io;

        /*
         * If we're in io-wq we can't rely on tw ordering guarantees, defer
         * flushing notif to io_send_zc_cleanup()
         */
        if (!(issue_flags & IO_URING_F_UNLOCKED)) {
                io_notif_flush(sr->notif);
                sr->notif = NULL;
                io_req_msg_cleanup(req, 0);
        }
        io_req_set_res(req, ret, IORING_CQE_F_MORE);
        return IOU_COMPLETE;
}

void io_sendrecv_fail(struct io_kiocb *req)
{
        struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);

        if (sr->done_io)
                req->cqe.res = sr->done_io;

        if ((req->flags & REQ_F_NEED_CLEANUP) &&
            (req->opcode == IORING_OP_SEND_ZC || req->opcode == IORING_OP_SENDMSG_ZC))
                req->cqe.flags |= IORING_CQE_F_MORE;
}

#define ACCEPT_FLAGS    (IORING_ACCEPT_MULTISHOT | IORING_ACCEPT_DONTWAIT | \
                         IORING_ACCEPT_POLL_FIRST)

int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_accept *accept = io_kiocb_to_cmd(req, struct io_accept);

        if (sqe->len || sqe->buf_index)
                return -EINVAL;

        accept->addr = u64_to_user_ptr(READ_ONCE(sqe->addr));
        accept->addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr2));
        accept->flags = READ_ONCE(sqe->accept_flags);
        accept->nofile = rlimit(RLIMIT_NOFILE);
        accept->iou_flags = READ_ONCE(sqe->ioprio);
        if (accept->iou_flags & ~ACCEPT_FLAGS)
                return -EINVAL;

        accept->file_slot = READ_ONCE(sqe->file_index);
        if (accept->file_slot) {
                if (accept->flags & SOCK_CLOEXEC)
                        return -EINVAL;
                if (accept->iou_flags & IORING_ACCEPT_MULTISHOT &&
                    accept->file_slot != IORING_FILE_INDEX_ALLOC)
                        return -EINVAL;
        }
        if (accept->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
                return -EINVAL;
        if (SOCK_NONBLOCK != O_NONBLOCK && (accept->flags & SOCK_NONBLOCK))
                accept->flags = (accept->flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
        if (accept->iou_flags & IORING_ACCEPT_MULTISHOT)
                req->flags |= REQ_F_APOLL_MULTISHOT;
        if (accept->iou_flags & IORING_ACCEPT_DONTWAIT)
                req->flags |= REQ_F_NOWAIT;
        return 0;
}

int io_accept(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_accept *accept = io_kiocb_to_cmd(req, struct io_accept);
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
        bool fixed = !!accept->file_slot;
        struct proto_accept_arg arg = {
                .flags = force_nonblock ? O_NONBLOCK : 0,
        };
        struct file *file;
        unsigned cflags;
        int ret, fd;

        if (!(req->flags & REQ_F_POLLED) &&
            accept->iou_flags & IORING_ACCEPT_POLL_FIRST)
                return -EAGAIN;

retry:
        if (!fixed) {
                fd = __get_unused_fd_flags(accept->flags, accept->nofile);
                if (unlikely(fd < 0))
                        return fd;
        }
        arg.err = 0;
        arg.is_empty = -1;
        file = do_accept(req->file, &arg, accept->addr, accept->addr_len,
                         accept->flags);
        if (IS_ERR(file)) {
                if (!fixed)
                        put_unused_fd(fd);
                ret = PTR_ERR(file);
                if (ret == -EAGAIN && force_nonblock &&
                    !(accept->iou_flags & IORING_ACCEPT_DONTWAIT))
                        return IOU_RETRY;

                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
        } else if (!fixed) {
                fd_install(fd, file);
                ret = fd;
        } else {
                ret = io_fixed_fd_install(req, issue_flags, file,
                                                accept->file_slot);
        }

        cflags = 0;
        if (!arg.is_empty)
                cflags |= IORING_CQE_F_SOCK_NONEMPTY;

        if (ret >= 0 && (req->flags & REQ_F_APOLL_MULTISHOT) &&
            io_req_post_cqe(req, ret, cflags | IORING_CQE_F_MORE)) {
                if (cflags & IORING_CQE_F_SOCK_NONEMPTY || arg.is_empty == -1)
                        goto retry;
                return IOU_RETRY;
        }

        io_req_set_res(req, ret, cflags);
        if (ret < 0)
                req_set_fail(req);
        return IOU_COMPLETE;
}

void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req)
{
        struct io_socket *sock = io_kiocb_to_cmd(req, struct io_socket);

        bctx->socket.family = sock->domain;
        bctx->socket.type = sock->type;
        bctx->socket.protocol = sock->protocol;
}

int io_socket_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_socket *sock = io_kiocb_to_cmd(req, struct io_socket);

        if (sqe->addr || sqe->rw_flags || sqe->buf_index)
                return -EINVAL;

        sock->domain = READ_ONCE(sqe->fd);
        sock->type = READ_ONCE(sqe->off);
        sock->protocol = READ_ONCE(sqe->len);
        sock->file_slot = READ_ONCE(sqe->file_index);
        sock->nofile = rlimit(RLIMIT_NOFILE);

        sock->flags = sock->type & ~SOCK_TYPE_MASK;
        if (sock->file_slot && (sock->flags & SOCK_CLOEXEC))
                return -EINVAL;
        if (sock->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
                return -EINVAL;
        return 0;
}

int io_socket(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_socket *sock = io_kiocb_to_cmd(req, struct io_socket);
        bool fixed = !!sock->file_slot;
        struct file *file;
        int ret, fd;

        if (!fixed) {
                fd = __get_unused_fd_flags(sock->flags, sock->nofile);
                if (unlikely(fd < 0))
                        return fd;
        }
        file = __sys_socket_file(sock->domain, sock->type, sock->protocol);
        if (IS_ERR(file)) {
                if (!fixed)
                        put_unused_fd(fd);
                ret = PTR_ERR(file);
                if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
                        return -EAGAIN;
                if (ret == -ERESTARTSYS)
                        ret = -EINTR;
                req_set_fail(req);
        } else if (!fixed) {
                fd_install(fd, file);
                ret = fd;
        } else {
                ret = io_fixed_fd_install(req, issue_flags, file,
                                            sock->file_slot);
        }
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}

int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_connect *conn = io_kiocb_to_cmd(req, struct io_connect);
        struct io_async_msghdr *io;

        if (sqe->len || sqe->buf_index || sqe->rw_flags || sqe->splice_fd_in)
                return -EINVAL;

        conn->addr = u64_to_user_ptr(READ_ONCE(sqe->addr));
        conn->addr_len =  READ_ONCE(sqe->addr2);
        conn->in_progress = conn->seen_econnaborted = false;

        io = io_msg_alloc_async(req);
        if (unlikely(!io))
                return -ENOMEM;

        return move_addr_to_kernel(conn->addr, conn->addr_len, &io->addr);
}

int io_connect(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_connect *connect = io_kiocb_to_cmd(req, struct io_connect);
        struct io_async_msghdr *io = req->async_data;
        unsigned file_flags;
        int ret;
        bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;

        if (connect->in_progress) {
                struct poll_table_struct pt = { ._key = EPOLLERR };

                if (vfs_poll(req->file, &pt) & EPOLLERR)
                        goto get_sock_err;
        }

        file_flags = force_nonblock ? O_NONBLOCK : 0;

        ret = __sys_connect_file(req->file, &io->addr, connect->addr_len,
                                 file_flags);
        if ((ret == -EAGAIN || ret == -EINPROGRESS || ret == -ECONNABORTED)
            && force_nonblock) {
                if (ret == -EINPROGRESS) {
                        connect->in_progress = true;
                } else if (ret == -ECONNABORTED) {
                        if (connect->seen_econnaborted)
                                goto out;
                        connect->seen_econnaborted = true;
                }
                return -EAGAIN;
        }
        if (connect->in_progress) {
                /*
                 * At least bluetooth will return -EBADFD on a re-connect
                 * attempt, and it's (supposedly) also valid to get -EISCONN
                 * which means the previous result is good. For both of these,
                 * grab the sock_error() and use that for the completion.
                 */
                if (ret == -EBADFD || ret == -EISCONN) {
get_sock_err:
                        ret = sock_error(sock_from_file(req->file)->sk);
                }
        }
        if (ret == -ERESTARTSYS)
                ret = -EINTR;
out:
        if (ret < 0)
                req_set_fail(req);
        io_req_msg_cleanup(req, issue_flags);
        io_req_set_res(req, ret, 0);
        return IOU_COMPLETE;
}

int io_bind_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_bind *bind = io_kiocb_to_cmd(req, struct io_bind);
        struct sockaddr __user *uaddr;
        struct io_async_msghdr *io;

        if (sqe->len || sqe->buf_index || sqe->rw_flags || sqe->splice_fd_in)
                return -EINVAL;

        uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
        bind->addr_len =  READ_ONCE(sqe->addr2);

        io = io_msg_alloc_async(req);
        if (unlikely(!io))
                return -ENOMEM;
        return move_addr_to_kernel(uaddr, bind->addr_len, &io->addr);
}

int io_bind(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_bind *bind = io_kiocb_to_cmd(req, struct io_bind);
        struct io_async_msghdr *io = req->async_data;
        struct socket *sock;
        int ret;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        ret = __sys_bind_socket(sock, &io->addr, bind->addr_len);
        if (ret < 0)
                req_set_fail(req);
        io_req_set_res(req, ret, 0);
        return 0;
}

int io_listen_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
        struct io_listen *listen = io_kiocb_to_cmd(req, struct io_listen);

        if (sqe->addr || sqe->buf_index || sqe->rw_flags || sqe->splice_fd_in || sqe->addr2)
                return -EINVAL;

        listen->backlog = READ_ONCE(sqe->len);
        return 0;
}

int io_listen(struct io_kiocb *req, unsigned int issue_flags)
{
        struct io_listen *listen = io_kiocb_to_cmd(req, struct io_listen);
        struct socket *sock;
        int ret;

        sock = sock_from_file(req->file);
        if (unlikely(!sock))
                return -ENOTSOCK;

        ret = __sys_listen_socket(sock, listen->backlog);
        if (ret < 0)
                req_set_fail(req);
        io_req_set_res(req, ret, 0);
        return 0;
}

void io_netmsg_cache_free(const void *entry)
{
        struct io_async_msghdr *kmsg = (struct io_async_msghdr *) entry;

        io_vec_free(&kmsg->vec);
        kfree(kmsg);
}