// SPDX-License-Identifier: GPL-2.0
/*
 * Ceph msgr2 protocol implementation
 *
 * Copyright (C) 2020 Ilya Dryomov <idryomov@gmail.com>
 */

#include <linux/ceph/ceph_debug.h>

#include <crypto/aead.h>
#include <crypto/algapi.h>  /* for crypto_memneq() */
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <linux/bvec.h>
#include <linux/crc32c.h>
#include <linux/net.h>
#include <linux/scatterlist.h>
#include <linux/socket.h>
#include <linux/sched/mm.h>
#include <net/sock.h>
#include <net/tcp.h>

#include <linux/ceph/ceph_features.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/libceph.h>
#include <linux/ceph/messenger.h>

#include "crypto.h"  /* for CEPH_KEY_LEN and CEPH_MAX_CON_SECRET_LEN */

#define FRAME_TAG_HELLO                 1
#define FRAME_TAG_AUTH_REQUEST          2
#define FRAME_TAG_AUTH_BAD_METHOD       3
#define FRAME_TAG_AUTH_REPLY_MORE       4
#define FRAME_TAG_AUTH_REQUEST_MORE     5
#define FRAME_TAG_AUTH_DONE             6
#define FRAME_TAG_AUTH_SIGNATURE        7
#define FRAME_TAG_CLIENT_IDENT          8
#define FRAME_TAG_SERVER_IDENT          9
#define FRAME_TAG_IDENT_MISSING_FEATURES 10
#define FRAME_TAG_SESSION_RECONNECT     11
#define FRAME_TAG_SESSION_RESET         12
#define FRAME_TAG_SESSION_RETRY         13
#define FRAME_TAG_SESSION_RETRY_GLOBAL  14
#define FRAME_TAG_SESSION_RECONNECT_OK  15
#define FRAME_TAG_WAIT                  16
#define FRAME_TAG_MESSAGE               17
#define FRAME_TAG_KEEPALIVE2            18
#define FRAME_TAG_KEEPALIVE2_ACK        19
#define FRAME_TAG_ACK                   20

#define FRAME_LATE_STATUS_ABORTED       0x1
#define FRAME_LATE_STATUS_COMPLETE      0xe
#define FRAME_LATE_STATUS_ABORTED_MASK  0xf

#define IN_S_HANDLE_PREAMBLE            1
#define IN_S_HANDLE_CONTROL             2
#define IN_S_HANDLE_CONTROL_REMAINDER   3
#define IN_S_PREPARE_READ_DATA          4
#define IN_S_PREPARE_READ_DATA_CONT     5
#define IN_S_HANDLE_EPILOGUE            6
#define IN_S_FINISH_SKIP                7

#define OUT_S_QUEUE_DATA                1
#define OUT_S_QUEUE_DATA_CONT           2
#define OUT_S_QUEUE_ENC_PAGE            3
#define OUT_S_QUEUE_ZEROS               4
#define OUT_S_FINISH_MESSAGE            5
#define OUT_S_GET_NEXT                  6

#define CTRL_BODY(p)    ((void *)(p) + CEPH_PREAMBLE_LEN)
#define FRONT_PAD(p)    ((void *)(p) + CEPH_EPILOGUE_SECURE_LEN)
#define MIDDLE_PAD(p)   (FRONT_PAD(p) + CEPH_GCM_BLOCK_LEN)
#define DATA_PAD(p)     (MIDDLE_PAD(p) + CEPH_GCM_BLOCK_LEN)

#define CEPH_MSG_FLAGS (MSG_DONTWAIT | MSG_NOSIGNAL)

static int do_recvmsg(struct socket *sock, struct iov_iter *it)
{
        struct msghdr msg = { .msg_flags = CEPH_MSG_FLAGS };
        int ret;

        msg.msg_iter = *it;
        while (iov_iter_count(it)) {
                ret = sock_recvmsg(sock, &msg, msg.msg_flags);
                if (ret <= 0) {
                        if (ret == -EAGAIN)
                                ret = 0;
                        return ret;
                }

                iov_iter_advance(it, ret);
        }

        WARN_ON(msg_data_left(&msg));
        return 1;
}

/*
 * Read as much as possible.
 *
 * Return:
 *   1 - done, nothing (else) to read
 *   0 - socket is empty, need to wait
 *  <0 - error
 */
static int ceph_tcp_recv(struct ceph_connection *con)
{
        int ret;

        dout("%s con %p %s %zu\n", __func__, con,
             iov_iter_is_discard(&con->v2.in_iter) ? "discard" : "need",
             iov_iter_count(&con->v2.in_iter));
        ret = do_recvmsg(con->sock, &con->v2.in_iter);
        dout("%s con %p ret %d left %zu\n", __func__, con, ret,
             iov_iter_count(&con->v2.in_iter));
        return ret;
}

static int do_sendmsg(struct socket *sock, struct iov_iter *it)
{
        struct msghdr msg = { .msg_flags = CEPH_MSG_FLAGS };
        int ret;

        msg.msg_iter = *it;
        while (iov_iter_count(it)) {
                ret = sock_sendmsg(sock, &msg);
                if (ret <= 0) {
                        if (ret == -EAGAIN)
                                ret = 0;
                        return ret;
                }

                iov_iter_advance(it, ret);
        }

        WARN_ON(msg_data_left(&msg));
        return 1;
}

static int do_try_sendpage(struct socket *sock, struct iov_iter *it)
{
        struct msghdr msg = { .msg_flags = CEPH_MSG_FLAGS };
        struct bio_vec bv;
        int ret;

        if (WARN_ON(!iov_iter_is_bvec(it)))
                return -EINVAL;

        while (iov_iter_count(it)) {
                /* iov_iter_iovec() for ITER_BVEC */
                bv.bv_page = it->bvec->bv_page;
                bv.bv_offset = it->bvec->bv_offset + it->iov_offset;
                bv.bv_len = min(iov_iter_count(it),
                                it->bvec->bv_len - it->iov_offset);

                /*
                 * sendpage cannot properly handle pages with
                 * page_count == 0, we need to fall back to sendmsg if
                 * that's the case.
                 *
                 * Same goes for slab pages: skb_can_coalesce() allows
                 * coalescing neighboring slab objects into a single frag
                 * which triggers one of hardened usercopy checks.
                 */
                if (sendpage_ok(bv.bv_page)) {
                        ret = sock->ops->sendpage(sock, bv.bv_page,
                                                  bv.bv_offset, bv.bv_len,
                                                  CEPH_MSG_FLAGS);
                } else {
                        iov_iter_bvec(&msg.msg_iter, WRITE, &bv, 1, bv.bv_len);
                        ret = sock_sendmsg(sock, &msg);
                }
                if (ret <= 0) {
                        if (ret == -EAGAIN)
                                ret = 0;
                        return ret;
                }

                iov_iter_advance(it, ret);
        }

        return 1;
}

/*
 * Write as much as possible.  The socket is expected to be corked,
 * so we don't bother with MSG_MORE/MSG_SENDPAGE_NOTLAST here.
 *
 * Return:
 *   1 - done, nothing (else) to write
 *   0 - socket is full, need to wait
 *  <0 - error
 */
static int ceph_tcp_send(struct ceph_connection *con)
{
        int ret;

        dout("%s con %p have %zu try_sendpage %d\n", __func__, con,
             iov_iter_count(&con->v2.out_iter), con->v2.out_iter_sendpage);
        if (con->v2.out_iter_sendpage)
                ret = do_try_sendpage(con->sock, &con->v2.out_iter);
        else
                ret = do_sendmsg(con->sock, &con->v2.out_iter);
        dout("%s con %p ret %d left %zu\n", __func__, con, ret,
             iov_iter_count(&con->v2.out_iter));
        return ret;
}

static void add_in_kvec(struct ceph_connection *con, void *buf, int len)
{
        BUG_ON(con->v2.in_kvec_cnt >= ARRAY_SIZE(con->v2.in_kvecs));
        WARN_ON(!iov_iter_is_kvec(&con->v2.in_iter));

        con->v2.in_kvecs[con->v2.in_kvec_cnt].iov_base = buf;
        con->v2.in_kvecs[con->v2.in_kvec_cnt].iov_len = len;
        con->v2.in_kvec_cnt++;

        con->v2.in_iter.nr_segs++;
        con->v2.in_iter.count += len;
}

static void reset_in_kvecs(struct ceph_connection *con)
{
        WARN_ON(iov_iter_count(&con->v2.in_iter));

        con->v2.in_kvec_cnt = 0;
        iov_iter_kvec(&con->v2.in_iter, READ, con->v2.in_kvecs, 0, 0);
}

static void set_in_bvec(struct ceph_connection *con, const struct bio_vec *bv)
{
        WARN_ON(iov_iter_count(&con->v2.in_iter));

        con->v2.in_bvec = *bv;
        iov_iter_bvec(&con->v2.in_iter, READ, &con->v2.in_bvec, 1, bv->bv_len);
}

static void set_in_skip(struct ceph_connection *con, int len)
{
        WARN_ON(iov_iter_count(&con->v2.in_iter));

        dout("%s con %p len %d\n", __func__, con, len);
        iov_iter_discard(&con->v2.in_iter, READ, len);
}

static void add_out_kvec(struct ceph_connection *con, void *buf, int len)
{
        BUG_ON(con->v2.out_kvec_cnt >= ARRAY_SIZE(con->v2.out_kvecs));
        WARN_ON(!iov_iter_is_kvec(&con->v2.out_iter));
        WARN_ON(con->v2.out_zero);

        con->v2.out_kvecs[con->v2.out_kvec_cnt].iov_base = buf;
        con->v2.out_kvecs[con->v2.out_kvec_cnt].iov_len = len;
        con->v2.out_kvec_cnt++;

        con->v2.out_iter.nr_segs++;
        con->v2.out_iter.count += len;
}

static void reset_out_kvecs(struct ceph_connection *con)
{
        WARN_ON(iov_iter_count(&con->v2.out_iter));
        WARN_ON(con->v2.out_zero);

        con->v2.out_kvec_cnt = 0;

        iov_iter_kvec(&con->v2.out_iter, WRITE, con->v2.out_kvecs, 0, 0);
        con->v2.out_iter_sendpage = false;
}

static void set_out_bvec(struct ceph_connection *con, const struct bio_vec *bv,
                         bool zerocopy)
{
        WARN_ON(iov_iter_count(&con->v2.out_iter));
        WARN_ON(con->v2.out_zero);

        con->v2.out_bvec = *bv;
        con->v2.out_iter_sendpage = zerocopy;
        iov_iter_bvec(&con->v2.out_iter, WRITE, &con->v2.out_bvec, 1,
                      con->v2.out_bvec.bv_len);
}

static void set_out_bvec_zero(struct ceph_connection *con)
{
        WARN_ON(iov_iter_count(&con->v2.out_iter));
        WARN_ON(!con->v2.out_zero);

        con->v2.out_bvec.bv_page = ceph_zero_page;
        con->v2.out_bvec.bv_offset = 0;
        con->v2.out_bvec.bv_len = min(con->v2.out_zero, (int)PAGE_SIZE);
        con->v2.out_iter_sendpage = true;
        iov_iter_bvec(&con->v2.out_iter, WRITE, &con->v2.out_bvec, 1,
                      con->v2.out_bvec.bv_len);
}

static void out_zero_add(struct ceph_connection *con, int len)
{
        dout("%s con %p len %d\n", __func__, con, len);
        con->v2.out_zero += len;
}

static void *alloc_conn_buf(struct ceph_connection *con, int len)
{
        void *buf;

        dout("%s con %p len %d\n", __func__, con, len);

        if (WARN_ON(con->v2.conn_buf_cnt >= ARRAY_SIZE(con->v2.conn_bufs)))
                return NULL;

        buf = ceph_kvmalloc(len, GFP_NOIO);
        if (!buf)
                return NULL;

        con->v2.conn_bufs[con->v2.conn_buf_cnt++] = buf;
        return buf;
}

static void free_conn_bufs(struct ceph_connection *con)
{
        while (con->v2.conn_buf_cnt)
                kvfree(con->v2.conn_bufs[--con->v2.conn_buf_cnt]);
}

static void add_in_sign_kvec(struct ceph_connection *con, void *buf, int len)
{
        BUG_ON(con->v2.in_sign_kvec_cnt >= ARRAY_SIZE(con->v2.in_sign_kvecs));

        con->v2.in_sign_kvecs[con->v2.in_sign_kvec_cnt].iov_base = buf;
        con->v2.in_sign_kvecs[con->v2.in_sign_kvec_cnt].iov_len = len;
        con->v2.in_sign_kvec_cnt++;
}

static void clear_in_sign_kvecs(struct ceph_connection *con)
{
        con->v2.in_sign_kvec_cnt = 0;
}

static void add_out_sign_kvec(struct ceph_connection *con, void *buf, int len)
{
        BUG_ON(con->v2.out_sign_kvec_cnt >= ARRAY_SIZE(con->v2.out_sign_kvecs));

        con->v2.out_sign_kvecs[con->v2.out_sign_kvec_cnt].iov_base = buf;
        con->v2.out_sign_kvecs[con->v2.out_sign_kvec_cnt].iov_len = len;
        con->v2.out_sign_kvec_cnt++;
}

static void clear_out_sign_kvecs(struct ceph_connection *con)
{
        con->v2.out_sign_kvec_cnt = 0;
}

static bool con_secure(struct ceph_connection *con)
{
        return con->v2.con_mode == CEPH_CON_MODE_SECURE;
}

static int front_len(const struct ceph_msg *msg)
{
        return le32_to_cpu(msg->hdr.front_len);
}

static int middle_len(const struct ceph_msg *msg)
{
        return le32_to_cpu(msg->hdr.middle_len);
}

static int data_len(const struct ceph_msg *msg)
{
        return le32_to_cpu(msg->hdr.data_len);
}

static bool need_padding(int len)
{
        return !IS_ALIGNED(len, CEPH_GCM_BLOCK_LEN);
}

static int padded_len(int len)
{
        return ALIGN(len, CEPH_GCM_BLOCK_LEN);
}

static int padding_len(int len)
{
        return padded_len(len) - len;
}

/* preamble + control segment */
static int head_onwire_len(int ctrl_len, bool secure)
{
        int head_len;
        int rem_len;

        if (secure) {
                head_len = CEPH_PREAMBLE_SECURE_LEN;
                if (ctrl_len > CEPH_PREAMBLE_INLINE_LEN) {
                        rem_len = ctrl_len - CEPH_PREAMBLE_INLINE_LEN;
                        head_len += padded_len(rem_len) + CEPH_GCM_TAG_LEN;
                }
        } else {
                head_len = CEPH_PREAMBLE_PLAIN_LEN;
                if (ctrl_len)
                        head_len += ctrl_len + CEPH_CRC_LEN;
        }
        return head_len;
}

/* front, middle and data segments + epilogue */
static int __tail_onwire_len(int front_len, int middle_len, int data_len,
                             bool secure)
{
        if (!front_len && !middle_len && !data_len)
                return 0;

        if (!secure)
                return front_len + middle_len + data_len +
                       CEPH_EPILOGUE_PLAIN_LEN;

        return padded_len(front_len) + padded_len(middle_len) +
               padded_len(data_len) + CEPH_EPILOGUE_SECURE_LEN;
}

static int tail_onwire_len(const struct ceph_msg *msg, bool secure)
{
        return __tail_onwire_len(front_len(msg), middle_len(msg),
                                 data_len(msg), secure);
}

/* head_onwire_len(sizeof(struct ceph_msg_header2), false) */
#define MESSAGE_HEAD_PLAIN_LEN  (CEPH_PREAMBLE_PLAIN_LEN +              \
                                 sizeof(struct ceph_msg_header2) +      \
                                 CEPH_CRC_LEN)

static const int frame_aligns[] = {
        sizeof(void *),
        sizeof(void *),
        sizeof(void *),
        PAGE_SIZE
};

/*
 * Discards trailing empty segments, unless there is just one segment.
 * A frame always has at least one (possibly empty) segment.
 */
static int calc_segment_count(const int *lens, int len_cnt)
{
        int i;

        for (i = len_cnt - 1; i >= 0; i--) {
                if (lens[i])
                        return i + 1;
        }

        return 1;
}

static void init_frame_desc(struct ceph_frame_desc *desc, int tag,
                            const int *lens, int len_cnt)
{
        int i;

        memset(desc, 0, sizeof(*desc));

        desc->fd_tag = tag;
        desc->fd_seg_cnt = calc_segment_count(lens, len_cnt);
        BUG_ON(desc->fd_seg_cnt > CEPH_FRAME_MAX_SEGMENT_COUNT);
        for (i = 0; i < desc->fd_seg_cnt; i++) {
                desc->fd_lens[i] = lens[i];
                desc->fd_aligns[i] = frame_aligns[i];
        }
}

/*
 * Preamble crc covers everything up to itself (28 bytes) and
 * is calculated and verified irrespective of the connection mode
 * (i.e. even if the frame is encrypted).
 */
static void encode_preamble(const struct ceph_frame_desc *desc, void *p)
{
        void *crcp = p + CEPH_PREAMBLE_LEN - CEPH_CRC_LEN;
        void *start = p;
        int i;

        memset(p, 0, CEPH_PREAMBLE_LEN);

        ceph_encode_8(&p, desc->fd_tag);
        ceph_encode_8(&p, desc->fd_seg_cnt);
        for (i = 0; i < desc->fd_seg_cnt; i++) {
                ceph_encode_32(&p, desc->fd_lens[i]);
                ceph_encode_16(&p, desc->fd_aligns[i]);
        }

        put_unaligned_le32(crc32c(0, start, crcp - start), crcp);
}

static int decode_preamble(void *p, struct ceph_frame_desc *desc)
{
        void *crcp = p + CEPH_PREAMBLE_LEN - CEPH_CRC_LEN;
        u32 crc, expected_crc;
        int i;

        crc = crc32c(0, p, crcp - p);
        expected_crc = get_unaligned_le32(crcp);
        if (crc != expected_crc) {
                pr_err("bad preamble crc, calculated %u, expected %u\n",
                       crc, expected_crc);
                return -EBADMSG;
        }

        memset(desc, 0, sizeof(*desc));

        desc->fd_tag = ceph_decode_8(&p);
        desc->fd_seg_cnt = ceph_decode_8(&p);
        if (desc->fd_seg_cnt < 1 ||
            desc->fd_seg_cnt > CEPH_FRAME_MAX_SEGMENT_COUNT) {
                pr_err("bad segment count %d\n", desc->fd_seg_cnt);
                return -EINVAL;
        }
        for (i = 0; i < desc->fd_seg_cnt; i++) {
                desc->fd_lens[i] = ceph_decode_32(&p);
                desc->fd_aligns[i] = ceph_decode_16(&p);
        }

        /*
         * This would fire for FRAME_TAG_WAIT (it has one empty
         * segment), but we should never get it as client.
         */
        if (!desc->fd_lens[desc->fd_seg_cnt - 1]) {
                pr_err("last segment empty\n");
                return -EINVAL;
        }

        if (desc->fd_lens[0] > CEPH_MSG_MAX_CONTROL_LEN) {
                pr_err("control segment too big %d\n", desc->fd_lens[0]);
                return -EINVAL;
        }
        if (desc->fd_lens[1] > CEPH_MSG_MAX_FRONT_LEN) {
                pr_err("front segment too big %d\n", desc->fd_lens[1]);
                return -EINVAL;
        }
        if (desc->fd_lens[2] > CEPH_MSG_MAX_MIDDLE_LEN) {
                pr_err("middle segment too big %d\n", desc->fd_lens[2]);
                return -EINVAL;
        }
        if (desc->fd_lens[3] > CEPH_MSG_MAX_DATA_LEN) {
                pr_err("data segment too big %d\n", desc->fd_lens[3]);
                return -EINVAL;
        }

        return 0;
}

static void encode_epilogue_plain(struct ceph_connection *con, bool aborted)
{
        con->v2.out_epil.late_status = aborted ? FRAME_LATE_STATUS_ABORTED :
                                                 FRAME_LATE_STATUS_COMPLETE;
        cpu_to_le32s(&con->v2.out_epil.front_crc);
        cpu_to_le32s(&con->v2.out_epil.middle_crc);
        cpu_to_le32s(&con->v2.out_epil.data_crc);
}

static void encode_epilogue_secure(struct ceph_connection *con, bool aborted)
{
        memset(&con->v2.out_epil, 0, sizeof(con->v2.out_epil));
        con->v2.out_epil.late_status = aborted ? FRAME_LATE_STATUS_ABORTED :
                                                 FRAME_LATE_STATUS_COMPLETE;
}

static int decode_epilogue(void *p, u32 *front_crc, u32 *middle_crc,
                           u32 *data_crc)
{
        u8 late_status;

        late_status = ceph_decode_8(&p);
        if ((late_status & FRAME_LATE_STATUS_ABORTED_MASK) !=
                        FRAME_LATE_STATUS_COMPLETE) {
                /* we should never get an aborted message as client */
                pr_err("bad late_status 0x%x\n", late_status);
                return -EINVAL;
        }

        if (front_crc && middle_crc && data_crc) {
                *front_crc = ceph_decode_32(&p);
                *middle_crc = ceph_decode_32(&p);
                *data_crc = ceph_decode_32(&p);
        }

        return 0;
}

static void fill_header(struct ceph_msg_header *hdr,
                        const struct ceph_msg_header2 *hdr2,
                        int front_len, int middle_len, int data_len,
                        const struct ceph_entity_name *peer_name)
{
        hdr->seq = hdr2->seq;
        hdr->tid = hdr2->tid;
        hdr->type = hdr2->type;
        hdr->priority = hdr2->priority;
        hdr->version = hdr2->version;
        hdr->front_len = cpu_to_le32(front_len);
        hdr->middle_len = cpu_to_le32(middle_len);
        hdr->data_len = cpu_to_le32(data_len);
        hdr->data_off = hdr2->data_off;
        hdr->src = *peer_name;
        hdr->compat_version = hdr2->compat_version;
        hdr->reserved = 0;
        hdr->crc = 0;
}

static void fill_header2(struct ceph_msg_header2 *hdr2,
                         const struct ceph_msg_header *hdr, u64 ack_seq)
{
        hdr2->seq = hdr->seq;
        hdr2->tid = hdr->tid;
        hdr2->type = hdr->type;
        hdr2->priority = hdr->priority;
        hdr2->version = hdr->version;
        hdr2->data_pre_padding_len = 0;
        hdr2->data_off = hdr->data_off;
        hdr2->ack_seq = cpu_to_le64(ack_seq);
        hdr2->flags = 0;
        hdr2->compat_version = hdr->compat_version;
        hdr2->reserved = 0;
}

static int verify_control_crc(struct ceph_connection *con)
{
        int ctrl_len = con->v2.in_desc.fd_lens[0];
        u32 crc, expected_crc;

        WARN_ON(con->v2.in_kvecs[0].iov_len != ctrl_len);
        WARN_ON(con->v2.in_kvecs[1].iov_len != CEPH_CRC_LEN);

        crc = crc32c(-1, con->v2.in_kvecs[0].iov_base, ctrl_len);
        expected_crc = get_unaligned_le32(con->v2.in_kvecs[1].iov_base);
        if (crc != expected_crc) {
                pr_err("bad control crc, calculated %u, expected %u\n",
                       crc, expected_crc);
                return -EBADMSG;
        }

        return 0;
}

static int verify_epilogue_crcs(struct ceph_connection *con, u32 front_crc,
                                u32 middle_crc, u32 data_crc)
{
        if (front_len(con->in_msg)) {
                con->in_front_crc = crc32c(-1, con->in_msg->front.iov_base,
                                           front_len(con->in_msg));
        } else {
                WARN_ON(!middle_len(con->in_msg) && !data_len(con->in_msg));
                con->in_front_crc = -1;
        }

        if (middle_len(con->in_msg))
                con->in_middle_crc = crc32c(-1,
                                            con->in_msg->middle->vec.iov_base,
                                            middle_len(con->in_msg));
        else if (data_len(con->in_msg))
                con->in_middle_crc = -1;
        else
                con->in_middle_crc = 0;

        if (!data_len(con->in_msg))
                con->in_data_crc = 0;

        dout("%s con %p msg %p crcs %u %u %u\n", __func__, con, con->in_msg,
             con->in_front_crc, con->in_middle_crc, con->in_data_crc);

        if (con->in_front_crc != front_crc) {
                pr_err("bad front crc, calculated %u, expected %u\n",
                       con->in_front_crc, front_crc);
                return -EBADMSG;
        }
        if (con->in_middle_crc != middle_crc) {
                pr_err("bad middle crc, calculated %u, expected %u\n",
                       con->in_middle_crc, middle_crc);
                return -EBADMSG;
        }
        if (con->in_data_crc != data_crc) {
                pr_err("bad data crc, calculated %u, expected %u\n",
                       con->in_data_crc, data_crc);
                return -EBADMSG;
        }

        return 0;
}

static int setup_crypto(struct ceph_connection *con,
                        const u8 *session_key, int session_key_len,
                        const u8 *con_secret, int con_secret_len)
{
        unsigned int noio_flag;
        int ret;

        dout("%s con %p con_mode %d session_key_len %d con_secret_len %d\n",
             __func__, con, con->v2.con_mode, session_key_len, con_secret_len);
        WARN_ON(con->v2.hmac_tfm || con->v2.gcm_tfm || con->v2.gcm_req);

        if (con->v2.con_mode != CEPH_CON_MODE_CRC &&
            con->v2.con_mode != CEPH_CON_MODE_SECURE) {
                pr_err("bad con_mode %d\n", con->v2.con_mode);
                return -EINVAL;
        }

        if (!session_key_len) {
                WARN_ON(con->v2.con_mode != CEPH_CON_MODE_CRC);
                WARN_ON(con_secret_len);
                return 0;  /* auth_none */
        }

        noio_flag = memalloc_noio_save();
        con->v2.hmac_tfm = crypto_alloc_shash("hmac(sha256)", 0, 0);
        memalloc_noio_restore(noio_flag);
        if (IS_ERR(con->v2.hmac_tfm)) {
                ret = PTR_ERR(con->v2.hmac_tfm);
                con->v2.hmac_tfm = NULL;
                pr_err("failed to allocate hmac tfm context: %d\n", ret);
                return ret;
        }

        WARN_ON((unsigned long)session_key &
                crypto_shash_alignmask(con->v2.hmac_tfm));
        ret = crypto_shash_setkey(con->v2.hmac_tfm, session_key,
                                  session_key_len);
        if (ret) {
                pr_err("failed to set hmac key: %d\n", ret);
                return ret;
        }

        if (con->v2.con_mode == CEPH_CON_MODE_CRC) {
                WARN_ON(con_secret_len);
                return 0;  /* auth_x, plain mode */
        }

        if (con_secret_len < CEPH_GCM_KEY_LEN + 2 * CEPH_GCM_IV_LEN) {
                pr_err("con_secret too small %d\n", con_secret_len);
                return -EINVAL;
        }

        noio_flag = memalloc_noio_save();
        con->v2.gcm_tfm = crypto_alloc_aead("gcm(aes)", 0, 0);
        memalloc_noio_restore(noio_flag);
        if (IS_ERR(con->v2.gcm_tfm)) {
                ret = PTR_ERR(con->v2.gcm_tfm);
                con->v2.gcm_tfm = NULL;
                pr_err("failed to allocate gcm tfm context: %d\n", ret);
                return ret;
        }

        WARN_ON((unsigned long)con_secret &
                crypto_aead_alignmask(con->v2.gcm_tfm));
        ret = crypto_aead_setkey(con->v2.gcm_tfm, con_secret, CEPH_GCM_KEY_LEN);
        if (ret) {
                pr_err("failed to set gcm key: %d\n", ret);
                return ret;
        }

        WARN_ON(crypto_aead_ivsize(con->v2.gcm_tfm) != CEPH_GCM_IV_LEN);
        ret = crypto_aead_setauthsize(con->v2.gcm_tfm, CEPH_GCM_TAG_LEN);
        if (ret) {
                pr_err("failed to set gcm tag size: %d\n", ret);
                return ret;
        }

        con->v2.gcm_req = aead_request_alloc(con->v2.gcm_tfm, GFP_NOIO);
        if (!con->v2.gcm_req) {
                pr_err("failed to allocate gcm request\n");
                return -ENOMEM;
        }

        crypto_init_wait(&con->v2.gcm_wait);
        aead_request_set_callback(con->v2.gcm_req, CRYPTO_TFM_REQ_MAY_BACKLOG,
                                  crypto_req_done, &con->v2.gcm_wait);

        memcpy(&con->v2.in_gcm_nonce, con_secret + CEPH_GCM_KEY_LEN,
               CEPH_GCM_IV_LEN);
        memcpy(&con->v2.out_gcm_nonce,
               con_secret + CEPH_GCM_KEY_LEN + CEPH_GCM_IV_LEN,
               CEPH_GCM_IV_LEN);
        return 0;  /* auth_x, secure mode */
}

static int hmac_sha256(struct ceph_connection *con, const struct kvec *kvecs,
                       int kvec_cnt, u8 *hmac)
{
        SHASH_DESC_ON_STACK(desc, con->v2.hmac_tfm);  /* tfm arg is ignored */
        int ret;
        int i;

        dout("%s con %p hmac_tfm %p kvec_cnt %d\n", __func__, con,
             con->v2.hmac_tfm, kvec_cnt);

        if (!con->v2.hmac_tfm) {
                memset(hmac, 0, SHA256_DIGEST_SIZE);
                return 0;  /* auth_none */
        }

        desc->tfm = con->v2.hmac_tfm;
        ret = crypto_shash_init(desc);
        if (ret)
                goto out;

        for (i = 0; i < kvec_cnt; i++) {
                WARN_ON((unsigned long)kvecs[i].iov_base &
                        crypto_shash_alignmask(con->v2.hmac_tfm));
                ret = crypto_shash_update(desc, kvecs[i].iov_base,
                                          kvecs[i].iov_len);
                if (ret)
                        goto out;
        }

        ret = crypto_shash_final(desc, hmac);

out:
        shash_desc_zero(desc);
        return ret;  /* auth_x, both plain and secure modes */
}

static void gcm_inc_nonce(struct ceph_gcm_nonce *nonce)
{
        u64 counter;

        counter = le64_to_cpu(nonce->counter);
        nonce->counter = cpu_to_le64(counter + 1);
}

static int gcm_crypt(struct ceph_connection *con, bool encrypt,
                     struct scatterlist *src, struct scatterlist *dst,
                     int src_len)
{
        struct ceph_gcm_nonce *nonce;
        int ret;

        nonce = encrypt ? &con->v2.out_gcm_nonce : &con->v2.in_gcm_nonce;

        aead_request_set_ad(con->v2.gcm_req, 0);  /* no AAD */
        aead_request_set_crypt(con->v2.gcm_req, src, dst, src_len, (u8 *)nonce);
        ret = crypto_wait_req(encrypt ? crypto_aead_encrypt(con->v2.gcm_req) :
                                        crypto_aead_decrypt(con->v2.gcm_req),
                              &con->v2.gcm_wait);
        if (ret)
                return ret;

        gcm_inc_nonce(nonce);
        return 0;
}

static void get_bvec_at(struct ceph_msg_data_cursor *cursor,
                        struct bio_vec *bv)
{
        struct page *page;
        size_t off, len;

        WARN_ON(!cursor->total_resid);

        /* skip zero-length data items */
        while (!cursor->resid)
                ceph_msg_data_advance(cursor, 0);

        /* get a piece of data, cursor isn't advanced */
        page = ceph_msg_data_next(cursor, &off, &len, NULL);

        bv->bv_page = page;
        bv->bv_offset = off;
        bv->bv_len = len;
}

static int calc_sg_cnt(void *buf, int buf_len)
{
        int sg_cnt;

        if (!buf_len)
                return 0;

        sg_cnt = need_padding(buf_len) ? 1 : 0;
        if (is_vmalloc_addr(buf)) {
                WARN_ON(offset_in_page(buf));
                sg_cnt += PAGE_ALIGN(buf_len) >> PAGE_SHIFT;
        } else {
                sg_cnt++;
        }

        return sg_cnt;
}

static int calc_sg_cnt_cursor(struct ceph_msg_data_cursor *cursor)
{
        int data_len = cursor->total_resid;
        struct bio_vec bv;
        int sg_cnt;

        if (!data_len)
                return 0;

        sg_cnt = need_padding(data_len) ? 1 : 0;
        do {
                get_bvec_at(cursor, &bv);
                sg_cnt++;

                ceph_msg_data_advance(cursor, bv.bv_len);
        } while (cursor->total_resid);

        return sg_cnt;
}

static void init_sgs(struct scatterlist **sg, void *buf, int buf_len, u8 *pad)
{
        void *end = buf + buf_len;
        struct page *page;
        int len;
        void *p;

        if (!buf_len)
                return;

        if (is_vmalloc_addr(buf)) {
                p = buf;
                do {
                        page = vmalloc_to_page(p);
                        len = min_t(int, end - p, PAGE_SIZE);
                        WARN_ON(!page || !len || offset_in_page(p));
                        sg_set_page(*sg, page, len, 0);
                        *sg = sg_next(*sg);
                        p += len;
                } while (p != end);
        } else {
                sg_set_buf(*sg, buf, buf_len);
                *sg = sg_next(*sg);
        }

        if (need_padding(buf_len)) {
                sg_set_buf(*sg, pad, padding_len(buf_len));
                *sg = sg_next(*sg);
        }
}

static void init_sgs_cursor(struct scatterlist **sg,
                            struct ceph_msg_data_cursor *cursor, u8 *pad)
{
        int data_len = cursor->total_resid;
        struct bio_vec bv;

        if (!data_len)
                return;

        do {
                get_bvec_at(cursor, &bv);
                sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset);
                *sg = sg_next(*sg);

                ceph_msg_data_advance(cursor, bv.bv_len);
        } while (cursor->total_resid);

        if (need_padding(data_len)) {
                sg_set_buf(*sg, pad, padding_len(data_len));
                *sg = sg_next(*sg);
        }
}

static int setup_message_sgs(struct sg_table *sgt, struct ceph_msg *msg,
                             u8 *front_pad, u8 *middle_pad, u8 *data_pad,
                             void *epilogue, bool add_tag)
{
        struct ceph_msg_data_cursor cursor;
        struct scatterlist *cur_sg;
        int sg_cnt;
        int ret;

        if (!front_len(msg) && !middle_len(msg) && !data_len(msg))
                return 0;

        sg_cnt = 1;  /* epilogue + [auth tag] */
        if (front_len(msg))
                sg_cnt += calc_sg_cnt(msg->front.iov_base,
                                      front_len(msg));
        if (middle_len(msg))
                sg_cnt += calc_sg_cnt(msg->middle->vec.iov_base,
                                      middle_len(msg));
        if (data_len(msg)) {
                ceph_msg_data_cursor_init(&cursor, msg, data_len(msg));
                sg_cnt += calc_sg_cnt_cursor(&cursor);
        }

        ret = sg_alloc_table(sgt, sg_cnt, GFP_NOIO);
        if (ret)
                return ret;

        cur_sg = sgt->sgl;
        if (front_len(msg))
                init_sgs(&cur_sg, msg->front.iov_base, front_len(msg),
                         front_pad);
        if (middle_len(msg))
                init_sgs(&cur_sg, msg->middle->vec.iov_base, middle_len(msg),
                         middle_pad);
        if (data_len(msg)) {
                ceph_msg_data_cursor_init(&cursor, msg, data_len(msg));
                init_sgs_cursor(&cur_sg, &cursor, data_pad);

        }

        WARN_ON(!sg_is_last(cur_sg));
        sg_set_buf(cur_sg, epilogue,
                   CEPH_GCM_BLOCK_LEN + (add_tag ? CEPH_GCM_TAG_LEN : 0));
        return 0;
}

static int decrypt_preamble(struct ceph_connection *con)
{
        struct scatterlist sg;

        sg_init_one(&sg, con->v2.in_buf, CEPH_PREAMBLE_SECURE_LEN);
        return gcm_crypt(con, false, &sg, &sg, CEPH_PREAMBLE_SECURE_LEN);
}

static int decrypt_control_remainder(struct ceph_connection *con)
{
        int ctrl_len = con->v2.in_desc.fd_lens[0];
        int rem_len = ctrl_len - CEPH_PREAMBLE_INLINE_LEN;
        int pt_len = padding_len(rem_len) + CEPH_GCM_TAG_LEN;
        struct scatterlist sgs[2];

        WARN_ON(con->v2.in_kvecs[0].iov_len != rem_len);
        WARN_ON(con->v2.in_kvecs[1].iov_len != pt_len);

        sg_init_table(sgs, 2);
        sg_set_buf(&sgs[0], con->v2.in_kvecs[0].iov_base, rem_len);
        sg_set_buf(&sgs[1], con->v2.in_buf, pt_len);

        return gcm_crypt(con, false, sgs, sgs,
                         padded_len(rem_len) + CEPH_GCM_TAG_LEN);
}

static int decrypt_message(struct ceph_connection *con)
{
        struct sg_table sgt = {};
        int ret;

        ret = setup_message_sgs(&sgt, con->in_msg, FRONT_PAD(con->v2.in_buf),
                        MIDDLE_PAD(con->v2.in_buf), DATA_PAD(con->v2.in_buf),
                        con->v2.in_buf, true);
        if (ret)
                goto out;

        ret = gcm_crypt(con, false, sgt.sgl, sgt.sgl,
                        tail_onwire_len(con->in_msg, true));

out:
        sg_free_table(&sgt);
        return ret;
}

static int prepare_banner(struct ceph_connection *con)
{
        int buf_len = CEPH_BANNER_V2_LEN + 2 + 8 + 8;
        void *buf, *p;

        buf = alloc_conn_buf(con, buf_len);
        if (!buf)
                return -ENOMEM;

        p = buf;
        ceph_encode_copy(&p, CEPH_BANNER_V2, CEPH_BANNER_V2_LEN);
        ceph_encode_16(&p, sizeof(u64) + sizeof(u64));
        ceph_encode_64(&p, CEPH_MSGR2_SUPPORTED_FEATURES);
        ceph_encode_64(&p, CEPH_MSGR2_REQUIRED_FEATURES);
        WARN_ON(p != buf + buf_len);

        add_out_kvec(con, buf, buf_len);
        add_out_sign_kvec(con, buf, buf_len);
        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
        return 0;
}

/*
 * base:
 *   preamble
 *   control body (ctrl_len bytes)
 *   space for control crc
 *
 * extdata (optional):
 *   control body (extdata_len bytes)
 *
 * Compute control crc and gather base and extdata into:
 *
 *   preamble
 *   control body (ctrl_len + extdata_len bytes)
 *   control crc
 *
 * Preamble should already be encoded at the start of base.
 */
static void prepare_head_plain(struct ceph_connection *con, void *base,
                               int ctrl_len, void *extdata, int extdata_len,
                               bool to_be_signed)
{
        int base_len = CEPH_PREAMBLE_LEN + ctrl_len + CEPH_CRC_LEN;
        void *crcp = base + base_len - CEPH_CRC_LEN;
        u32 crc;

        crc = crc32c(-1, CTRL_BODY(base), ctrl_len);
        if (extdata_len)
                crc = crc32c(crc, extdata, extdata_len);
        put_unaligned_le32(crc, crcp);

        if (!extdata_len) {
                add_out_kvec(con, base, base_len);
                if (to_be_signed)
                        add_out_sign_kvec(con, base, base_len);
                return;
        }

        add_out_kvec(con, base, crcp - base);
        add_out_kvec(con, extdata, extdata_len);
        add_out_kvec(con, crcp, CEPH_CRC_LEN);
        if (to_be_signed) {
                add_out_sign_kvec(con, base, crcp - base);
                add_out_sign_kvec(con, extdata, extdata_len);
                add_out_sign_kvec(con, crcp, CEPH_CRC_LEN);
        }
}

static int prepare_head_secure_small(struct ceph_connection *con,
                                     void *base, int ctrl_len)
{
        struct scatterlist sg;
        int ret;

        /* inline buffer padding? */
        if (ctrl_len < CEPH_PREAMBLE_INLINE_LEN)
                memset(CTRL_BODY(base) + ctrl_len, 0,
                       CEPH_PREAMBLE_INLINE_LEN - ctrl_len);

        sg_init_one(&sg, base, CEPH_PREAMBLE_SECURE_LEN);
        ret = gcm_crypt(con, true, &sg, &sg,
                        CEPH_PREAMBLE_SECURE_LEN - CEPH_GCM_TAG_LEN);
        if (ret)
                return ret;

        add_out_kvec(con, base, CEPH_PREAMBLE_SECURE_LEN);
        return 0;
}

/*
 * base:
 *   preamble
 *   control body (ctrl_len bytes)
 *   space for padding, if needed
 *   space for control remainder auth tag
 *   space for preamble auth tag
 *
 * Encrypt preamble and the inline portion, then encrypt the remainder
 * and gather into:
 *
 *   preamble
 *   control body (48 bytes)
 *   preamble auth tag
 *   control body (ctrl_len - 48 bytes)
 *   zero padding, if needed
 *   control remainder auth tag
 *
 * Preamble should already be encoded at the start of base.
 */
static int prepare_head_secure_big(struct ceph_connection *con,
                                   void *base, int ctrl_len)
{
        int rem_len = ctrl_len - CEPH_PREAMBLE_INLINE_LEN;
        void *rem = CTRL_BODY(base) + CEPH_PREAMBLE_INLINE_LEN;
        void *rem_tag = rem + padded_len(rem_len);
        void *pmbl_tag = rem_tag + CEPH_GCM_TAG_LEN;
        struct scatterlist sgs[2];
        int ret;

        sg_init_table(sgs, 2);
        sg_set_buf(&sgs[0], base, rem - base);
        sg_set_buf(&sgs[1], pmbl_tag, CEPH_GCM_TAG_LEN);
        ret = gcm_crypt(con, true, sgs, sgs, rem - base);
        if (ret)
                return ret;

        /* control remainder padding? */
        if (need_padding(rem_len))
                memset(rem + rem_len, 0, padding_len(rem_len));

        sg_init_one(&sgs[0], rem, pmbl_tag - rem);
        ret = gcm_crypt(con, true, sgs, sgs, rem_tag - rem);
        if (ret)
                return ret;

        add_out_kvec(con, base, rem - base);
        add_out_kvec(con, pmbl_tag, CEPH_GCM_TAG_LEN);
        add_out_kvec(con, rem, pmbl_tag - rem);
        return 0;
}

static int __prepare_control(struct ceph_connection *con, int tag,
                             void *base, int ctrl_len, void *extdata,
                             int extdata_len, bool to_be_signed)
{
        int total_len = ctrl_len + extdata_len;
        struct ceph_frame_desc desc;
        int ret;

        dout("%s con %p tag %d len %d (%d+%d)\n", __func__, con, tag,
             total_len, ctrl_len, extdata_len);

        /* extdata may be vmalloc'ed but not base */
        if (WARN_ON(is_vmalloc_addr(base) || !ctrl_len))
                return -EINVAL;

        init_frame_desc(&desc, tag, &total_len, 1);
        encode_preamble(&desc, base);

        if (con_secure(con)) {
                if (WARN_ON(extdata_len || to_be_signed))
                        return -EINVAL;

                if (ctrl_len <= CEPH_PREAMBLE_INLINE_LEN)
                        /* fully inlined, inline buffer may need padding */
                        ret = prepare_head_secure_small(con, base, ctrl_len);
                else
                        /* partially inlined, inline buffer is full */
                        ret = prepare_head_secure_big(con, base, ctrl_len);
                if (ret)
                        return ret;
        } else {
                prepare_head_plain(con, base, ctrl_len, extdata, extdata_len,
                                   to_be_signed);
        }

        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
        return 0;
}

static int prepare_control(struct ceph_connection *con, int tag,
                           void *base, int ctrl_len)
{
        return __prepare_control(con, tag, base, ctrl_len, NULL, 0, false);
}

static int prepare_hello(struct ceph_connection *con)
{
        void *buf, *p;
        int ctrl_len;

        ctrl_len = 1 + ceph_entity_addr_encoding_len(&con->peer_addr);
        buf = alloc_conn_buf(con, head_onwire_len(ctrl_len, false));
        if (!buf)
                return -ENOMEM;

        p = CTRL_BODY(buf);
        ceph_encode_8(&p, CEPH_ENTITY_TYPE_CLIENT);
        ceph_encode_entity_addr(&p, &con->peer_addr);
        WARN_ON(p != CTRL_BODY(buf) + ctrl_len);

        return __prepare_control(con, FRAME_TAG_HELLO, buf, ctrl_len,
                                 NULL, 0, true);
}

/* so that head_onwire_len(AUTH_BUF_LEN, false) is 512 */
#define AUTH_BUF_LEN    (512 - CEPH_CRC_LEN - CEPH_PREAMBLE_PLAIN_LEN)

static int prepare_auth_request(struct ceph_connection *con)
{
        void *authorizer, *authorizer_copy;
        int ctrl_len, authorizer_len;
        void *buf;
        int ret;

        ctrl_len = AUTH_BUF_LEN;
        buf = alloc_conn_buf(con, head_onwire_len(ctrl_len, false));
        if (!buf)
                return -ENOMEM;

        mutex_unlock(&con->mutex);
        ret = con->ops->get_auth_request(con, CTRL_BODY(buf), &ctrl_len,
                                         &authorizer, &authorizer_len);
        mutex_lock(&con->mutex);
        if (con->state != CEPH_CON_S_V2_HELLO) {
                dout("%s con %p state changed to %d\n", __func__, con,
                     con->state);
                return -EAGAIN;
        }

        dout("%s con %p get_auth_request ret %d\n", __func__, con, ret);
        if (ret)
                return ret;

        authorizer_copy = alloc_conn_buf(con, authorizer_len);
        if (!authorizer_copy)
                return -ENOMEM;

        memcpy(authorizer_copy, authorizer, authorizer_len);

        return __prepare_control(con, FRAME_TAG_AUTH_REQUEST, buf, ctrl_len,
                                 authorizer_copy, authorizer_len, true);
}

static int prepare_auth_request_more(struct ceph_connection *con,
                                     void *reply, int reply_len)
{
        int ctrl_len, authorizer_len;
        void *authorizer;
        void *buf;
        int ret;

        ctrl_len = AUTH_BUF_LEN;
        buf = alloc_conn_buf(con, head_onwire_len(ctrl_len, false));
        if (!buf)
                return -ENOMEM;

        mutex_unlock(&con->mutex);
        ret = con->ops->handle_auth_reply_more(con, reply, reply_len,
                                               CTRL_BODY(buf), &ctrl_len,
                                               &authorizer, &authorizer_len);
        mutex_lock(&con->mutex);
        if (con->state != CEPH_CON_S_V2_AUTH) {
                dout("%s con %p state changed to %d\n", __func__, con,
                     con->state);
                return -EAGAIN;
        }

        dout("%s con %p handle_auth_reply_more ret %d\n", __func__, con, ret);
        if (ret)
                return ret;

        return __prepare_control(con, FRAME_TAG_AUTH_REQUEST_MORE, buf,
                                 ctrl_len, authorizer, authorizer_len, true);
}

static int prepare_auth_signature(struct ceph_connection *con)
{
        void *buf;
        int ret;

        buf = alloc_conn_buf(con, head_onwire_len(SHA256_DIGEST_SIZE,
                                                  con_secure(con)));
        if (!buf)
                return -ENOMEM;

        ret = hmac_sha256(con, con->v2.in_sign_kvecs, con->v2.in_sign_kvec_cnt,
                          CTRL_BODY(buf));
        if (ret)
                return ret;

        return prepare_control(con, FRAME_TAG_AUTH_SIGNATURE, buf,
                               SHA256_DIGEST_SIZE);
}

static int prepare_client_ident(struct ceph_connection *con)
{
        struct ceph_entity_addr *my_addr = &con->msgr->inst.addr;
        struct ceph_client *client = from_msgr(con->msgr);
        u64 global_id = ceph_client_gid(client);
        void *buf, *p;
        int ctrl_len;

        WARN_ON(con->v2.server_cookie);
        WARN_ON(con->v2.connect_seq);
        WARN_ON(con->v2.peer_global_seq);

        if (!con->v2.client_cookie) {
                do {
                        get_random_bytes(&con->v2.client_cookie,
                                         sizeof(con->v2.client_cookie));
                } while (!con->v2.client_cookie);
                dout("%s con %p generated cookie 0x%llx\n", __func__, con,
                     con->v2.client_cookie);
        } else {
                dout("%s con %p cookie already set 0x%llx\n", __func__, con,
                     con->v2.client_cookie);
        }

        dout("%s con %p my_addr %s/%u peer_addr %s/%u global_id %llu global_seq %llu features 0x%llx required_features 0x%llx cookie 0x%llx\n",
             __func__, con, ceph_pr_addr(my_addr), le32_to_cpu(my_addr->nonce),
             ceph_pr_addr(&con->peer_addr), le32_to_cpu(con->peer_addr.nonce),
             global_id, con->v2.global_seq, client->supported_features,
             client->required_features, con->v2.client_cookie);

        ctrl_len = 1 + 4 + ceph_entity_addr_encoding_len(my_addr) +
                   ceph_entity_addr_encoding_len(&con->peer_addr) + 6 * 8;
        buf = alloc_conn_buf(con, head_onwire_len(ctrl_len, con_secure(con)));
        if (!buf)
                return -ENOMEM;

        p = CTRL_BODY(buf);
        ceph_encode_8(&p, 2);  /* addrvec marker */
        ceph_encode_32(&p, 1);  /* addr_cnt */
        ceph_encode_entity_addr(&p, my_addr);
        ceph_encode_entity_addr(&p, &con->peer_addr);
        ceph_encode_64(&p, global_id);
        ceph_encode_64(&p, con->v2.global_seq);
        ceph_encode_64(&p, client->supported_features);
        ceph_encode_64(&p, client->required_features);
        ceph_encode_64(&p, 0);  /* flags */
        ceph_encode_64(&p, con->v2.client_cookie);
        WARN_ON(p != CTRL_BODY(buf) + ctrl_len);

        return prepare_control(con, FRAME_TAG_CLIENT_IDENT, buf, ctrl_len);
}

static int prepare_session_reconnect(struct ceph_connection *con)
{
        struct ceph_entity_addr *my_addr = &con->msgr->inst.addr;
        void *buf, *p;
        int ctrl_len;

        WARN_ON(!con->v2.client_cookie);
        WARN_ON(!con->v2.server_cookie);
        WARN_ON(!con->v2.connect_seq);
        WARN_ON(!con->v2.peer_global_seq);

        dout("%s con %p my_addr %s/%u client_cookie 0x%llx server_cookie 0x%llx global_seq %llu connect_seq %llu in_seq %llu\n",
             __func__, con, ceph_pr_addr(my_addr), le32_to_cpu(my_addr->nonce),
             con->v2.client_cookie, con->v2.server_cookie, con->v2.global_seq,
             con->v2.connect_seq, con->in_seq);

        ctrl_len = 1 + 4 + ceph_entity_addr_encoding_len(my_addr) + 5 * 8;
        buf = alloc_conn_buf(con, head_onwire_len(ctrl_len, con_secure(con)));
        if (!buf)
                return -ENOMEM;

        p = CTRL_BODY(buf);
        ceph_encode_8(&p, 2);  /* entity_addrvec_t marker */
        ceph_encode_32(&p, 1);  /* my_addrs len */
        ceph_encode_entity_addr(&p, my_addr);
        ceph_encode_64(&p, con->v2.client_cookie);
        ceph_encode_64(&p, con->v2.server_cookie);
        ceph_encode_64(&p, con->v2.global_seq);
        ceph_encode_64(&p, con->v2.connect_seq);
        ceph_encode_64(&p, con->in_seq);
        WARN_ON(p != CTRL_BODY(buf) + ctrl_len);

        return prepare_control(con, FRAME_TAG_SESSION_RECONNECT, buf, ctrl_len);
}

static int prepare_keepalive2(struct ceph_connection *con)
{
        struct ceph_timespec *ts = CTRL_BODY(con->v2.out_buf);
        struct timespec64 now;

        ktime_get_real_ts64(&now);
        dout("%s con %p timestamp %lld.%09ld\n", __func__, con, now.tv_sec,
             now.tv_nsec);

        ceph_encode_timespec64(ts, &now);

        reset_out_kvecs(con);
        return prepare_control(con, FRAME_TAG_KEEPALIVE2, con->v2.out_buf,
                               sizeof(struct ceph_timespec));
}

static int prepare_ack(struct ceph_connection *con)
{
        void *p;

        dout("%s con %p in_seq_acked %llu -> %llu\n", __func__, con,
             con->in_seq_acked, con->in_seq);
        con->in_seq_acked = con->in_seq;

        p = CTRL_BODY(con->v2.out_buf);
        ceph_encode_64(&p, con->in_seq_acked);

        reset_out_kvecs(con);
        return prepare_control(con, FRAME_TAG_ACK, con->v2.out_buf, 8);
}

static void prepare_epilogue_plain(struct ceph_connection *con, bool aborted)
{
        dout("%s con %p msg %p aborted %d crcs %u %u %u\n", __func__, con,
             con->out_msg, aborted, con->v2.out_epil.front_crc,
             con->v2.out_epil.middle_crc, con->v2.out_epil.data_crc);

        encode_epilogue_plain(con, aborted);
        add_out_kvec(con, &con->v2.out_epil, CEPH_EPILOGUE_PLAIN_LEN);
}

/*
 * For "used" empty segments, crc is -1.  For unused (trailing)
 * segments, crc is 0.
 */
static void prepare_message_plain(struct ceph_connection *con)
{
        struct ceph_msg *msg = con->out_msg;

        prepare_head_plain(con, con->v2.out_buf,
                           sizeof(struct ceph_msg_header2), NULL, 0, false);

        if (!front_len(msg) && !middle_len(msg)) {
                if (!data_len(msg)) {
                        /*
                         * Empty message: once the head is written,
                         * we are done -- there is no epilogue.
                         */
                        con->v2.out_state = OUT_S_FINISH_MESSAGE;
                        return;
                }

                con->v2.out_epil.front_crc = -1;
                con->v2.out_epil.middle_crc = -1;
                con->v2.out_state = OUT_S_QUEUE_DATA;
                return;
        }

        if (front_len(msg)) {
                con->v2.out_epil.front_crc = crc32c(-1, msg->front.iov_base,
                                                    front_len(msg));
                add_out_kvec(con, msg->front.iov_base, front_len(msg));
        } else {
                /* middle (at least) is there, checked above */
                con->v2.out_epil.front_crc = -1;
        }

        if (middle_len(msg)) {
                con->v2.out_epil.middle_crc =
                        crc32c(-1, msg->middle->vec.iov_base, middle_len(msg));
                add_out_kvec(con, msg->middle->vec.iov_base, middle_len(msg));
        } else {
                con->v2.out_epil.middle_crc = data_len(msg) ? -1 : 0;
        }

        if (data_len(msg)) {
                con->v2.out_state = OUT_S_QUEUE_DATA;
        } else {
                con->v2.out_epil.data_crc = 0;
                prepare_epilogue_plain(con, false);
                con->v2.out_state = OUT_S_FINISH_MESSAGE;
        }
}

/*
 * Unfortunately the kernel crypto API doesn't support streaming
 * (piecewise) operation for AEAD algorithms, so we can't get away
 * with a fixed size buffer and a couple sgs.  Instead, we have to
 * allocate pages for the entire tail of the message (currently up
 * to ~32M) and two sgs arrays (up to ~256K each)...
 */
static int prepare_message_secure(struct ceph_connection *con)
{
        void *zerop = page_address(ceph_zero_page);
        struct sg_table enc_sgt = {};
        struct sg_table sgt = {};
        struct page **enc_pages;
        int enc_page_cnt;
        int tail_len;
        int ret;

        ret = prepare_head_secure_small(con, con->v2.out_buf,
                                        sizeof(struct ceph_msg_header2));
        if (ret)
                return ret;

        tail_len = tail_onwire_len(con->out_msg, true);
        if (!tail_len) {
                /*
                 * Empty message: once the head is written,
                 * we are done -- there is no epilogue.
                 */
                con->v2.out_state = OUT_S_FINISH_MESSAGE;
                return 0;
        }

        encode_epilogue_secure(con, false);
        ret = setup_message_sgs(&sgt, con->out_msg, zerop, zerop, zerop,
                                &con->v2.out_epil, false);
        if (ret)
                goto out;

        enc_page_cnt = calc_pages_for(0, tail_len);
        enc_pages = ceph_alloc_page_vector(enc_page_cnt, GFP_NOIO);
        if (IS_ERR(enc_pages)) {
                ret = PTR_ERR(enc_pages);
                goto out;
        }

        WARN_ON(con->v2.out_enc_pages || con->v2.out_enc_page_cnt);
        con->v2.out_enc_pages = enc_pages;
        con->v2.out_enc_page_cnt = enc_page_cnt;
        con->v2.out_enc_resid = tail_len;
        con->v2.out_enc_i = 0;

        ret = sg_alloc_table_from_pages(&enc_sgt, enc_pages, enc_page_cnt,
                                        0, tail_len, GFP_NOIO);
        if (ret)
                goto out;

        ret = gcm_crypt(con, true, sgt.sgl, enc_sgt.sgl,
                        tail_len - CEPH_GCM_TAG_LEN);
        if (ret)
                goto out;

        dout("%s con %p msg %p sg_cnt %d enc_page_cnt %d\n", __func__, con,
             con->out_msg, sgt.orig_nents, enc_page_cnt);
        con->v2.out_state = OUT_S_QUEUE_ENC_PAGE;

out:
        sg_free_table(&sgt);
        sg_free_table(&enc_sgt);
        return ret;
}

static int prepare_message(struct ceph_connection *con)
{
        int lens[] = {
                sizeof(struct ceph_msg_header2),
                front_len(con->out_msg),
                middle_len(con->out_msg),
                data_len(con->out_msg)
        };
        struct ceph_frame_desc desc;
        int ret;

        dout("%s con %p msg %p logical %d+%d+%d+%d\n", __func__, con,
             con->out_msg, lens[0], lens[1], lens[2], lens[3]);

        if (con->in_seq > con->in_seq_acked) {
                dout("%s con %p in_seq_acked %llu -> %llu\n", __func__, con,
                     con->in_seq_acked, con->in_seq);
                con->in_seq_acked = con->in_seq;
        }

        reset_out_kvecs(con);
        init_frame_desc(&desc, FRAME_TAG_MESSAGE, lens, 4);
        encode_preamble(&desc, con->v2.out_buf);
        fill_header2(CTRL_BODY(con->v2.out_buf), &con->out_msg->hdr,
                     con->in_seq_acked);

        if (con_secure(con)) {
                ret = prepare_message_secure(con);
                if (ret)
                        return ret;
        } else {
                prepare_message_plain(con);
        }

        ceph_con_flag_set(con, CEPH_CON_F_WRITE_PENDING);
        return 0;
}

static int prepare_read_banner_prefix(struct ceph_connection *con)
{
        void *buf;

        buf = alloc_conn_buf(con, CEPH_BANNER_V2_PREFIX_LEN);
        if (!buf)
                return -ENOMEM;

        reset_in_kvecs(con);
        add_in_kvec(con, buf, CEPH_BANNER_V2_PREFIX_LEN);
        add_in_sign_kvec(con, buf, CEPH_BANNER_V2_PREFIX_LEN);
        con->state = CEPH_CON_S_V2_BANNER_PREFIX;
        return 0;
}

static int prepare_read_banner_payload(struct ceph_connection *con,
                                       int payload_len)
{
        void *buf;

        buf = alloc_conn_buf(con, payload_len);
        if (!buf)
                return -ENOMEM;

        reset_in_kvecs(con);
        add_in_kvec(con, buf, payload_len);
        add_in_sign_kvec(con, buf, payload_len);
        con->state = CEPH_CON_S_V2_BANNER_PAYLOAD;
        return 0;
}

static void prepare_read_preamble(struct ceph_connection *con)
{
        reset_in_kvecs(con);
        add_in_kvec(con, con->v2.in_buf,
                    con_secure(con) ? CEPH_PREAMBLE_SECURE_LEN :
                                      CEPH_PREAMBLE_PLAIN_LEN);
        con->v2.in_state = IN_S_HANDLE_PREAMBLE;
}

static int prepare_read_control(struct ceph_connection *con)
{
        int ctrl_len = con->v2.in_desc.fd_lens[0];
        int head_len;
        void *buf;

        reset_in_kvecs(con);
        if (con->state == CEPH_CON_S_V2_HELLO ||
            con->state == CEPH_CON_S_V2_AUTH) {
                head_len = head_onwire_len(ctrl_len, false);
                buf = alloc_conn_buf(con, head_len);
                if (!buf)
                        return -ENOMEM;

                /* preserve preamble */
                memcpy(buf, con->v2.in_buf, CEPH_PREAMBLE_LEN);

                add_in_kvec(con, CTRL_BODY(buf), ctrl_len);
                add_in_kvec(con, CTRL_BODY(buf) + ctrl_len, CEPH_CRC_LEN);
                add_in_sign_kvec(con, buf, head_len);
        } else {
                if (ctrl_len > CEPH_PREAMBLE_INLINE_LEN) {
                        buf = alloc_conn_buf(con, ctrl_len);
                        if (!buf)
                                return -ENOMEM;

                        add_in_kvec(con, buf, ctrl_len);
                } else {
                        add_in_kvec(con, CTRL_BODY(con->v2.in_buf), ctrl_len);
                }
                add_in_kvec(con, con->v2.in_buf, CEPH_CRC_LEN);
        }
        con->v2.in_state = IN_S_HANDLE_CONTROL;
        return 0;
}

static int prepare_read_control_remainder(struct ceph_connection *con)
{
        int ctrl_len = con->v2.in_desc.fd_lens[0];
        int rem_len = ctrl_len - CEPH_PREAMBLE_INLINE_LEN;
        void *buf;

        buf = alloc_conn_buf(con, ctrl_len);
        if (!buf)
                return -ENOMEM;

        memcpy(buf, CTRL_BODY(con->v2.in_buf), CEPH_PREAMBLE_INLINE_LEN);

        reset_in_kvecs(con);
        add_in_kvec(con, buf + CEPH_PREAMBLE_INLINE_LEN, rem_len);
        add_in_kvec(con, con->v2.in_buf,
                    padding_len(rem_len) + CEPH_GCM_TAG_LEN);
        con->v2.in_state = IN_S_HANDLE_CONTROL_REMAINDER;
        return 0;
}

static void prepare_read_data(struct ceph_connection *con)
{
        struct bio_vec bv;

        if (!con_secure(con))
                con->in_data_crc = -1;
        ceph_msg_data_cursor_init(&con->v2.in_cursor, con->in_msg,
                                  data_len(con->in_msg));

        get_bvec_at(&con->v2.in_cursor, &bv);
        set_in_bvec(con, &bv);
        con->v2.in_state = IN_S_PREPARE_READ_DATA_CONT;
}

static void prepare_read_data_cont(struct ceph_connection *con)
{
        struct bio_vec bv;

        if (!con_secure(con))
                con->in_data_crc = ceph_crc32c_page(con->in_data_crc,
                                                    con->v2.in_bvec.bv_page,
                                                    con->v2.in_bvec.bv_offset,
                                                    con->v2.in_bvec.bv_len);

        ceph_msg_data_advance(&con->v2.in_cursor, con->v2.in_bvec.bv_len);
        if (con->v2.in_cursor.total_resid) {
                get_bvec_at(&con->v2.in_cursor, &bv);
                set_in_bvec(con, &bv);
                WARN_ON(con->v2.in_state != IN_S_PREPARE_READ_DATA_CONT);
                return;
        }

        /*
         * We've read all data.  Prepare to read data padding (if any)
         * and epilogue.
         */
        reset_in_kvecs(con);
        if (con_secure(con)) {
                if (need_padding(data_len(con->in_msg)))
                        add_in_kvec(con, DATA_PAD(con->v2.in_buf),
                                    padding_len(data_len(con->in_msg)));
                add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_SECURE_LEN);
        } else {
                add_in_kvec(con, con->v2.in_buf, CEPH_EPILOGUE_PLAIN_LEN);
        }
        con->v2.in_state = IN_S_HANDLE_EPILOGUE;
}

static void __finish_skip(struct ceph_connection *con)
{
        con->in_seq++;
        prepare_read_preamble(con);
}

static void prepare_skip_message(struct ceph_connection *con)
{
        struct ceph_frame_desc *desc = &con->v2.in_desc;
        int tail_len;

        dout("%s con %p %d+%d+%d\n", __func__, con, desc->fd_lens[1],
             desc->fd_lens[2], desc->fd_lens[3]);

        tail_len = __tail_onwire_len(desc->fd_lens[1], desc->fd_lens[2],
                                     desc->fd_lens[3], con_secure(con));
        if (!tail_len) {
                __finish_skip(con);
        } else {
                set_in_skip(con, tail_len);
                con->v2.in_state = IN_S_FINISH_SKIP;
        }
}

static int process_banner_prefix(struct ceph_connection *con)
{
        int payload_len;
        void *p;

        WARN_ON(con->v2.in_kvecs[0].iov_len != CEPH_BANNER_V2_PREFIX_LEN);

        p = con->v2.in_kvecs[0].iov_base;
        if (memcmp(p, CEPH_BANNER_V2, CEPH_BANNER_V2_LEN)) {
                if (!memcmp(p, CEPH_BANNER, CEPH_BANNER_LEN))
                        con->error_msg = "server is speaking msgr1 protocol";
                else
                        con->error_msg = "protocol error, bad banner";
                return -EINVAL;
        }

        p += CEPH_BANNER_V2_LEN;
        payload_len = ceph_decode_16(&p);
        dout("%s con %p payload_len %d\n", __func__, con, payload_len);

        return prepare_read_banner_payload(con, payload_len);
}

static int process_banner_payload(struct ceph_connection *con)
{
        void *end = con->v2.in_kvecs[0].iov_base + con->v2.in_kvecs[0].iov_len;
        u64 feat = CEPH_MSGR2_SUPPORTED_FEATURES;
        u64 req_feat = CEPH_MSGR2_REQUIRED_FEATURES;
        u64 server_feat, server_req_feat;
        void *p;
        int ret;

        p = con->v2.in_kvecs[0].iov_base;
        ceph_decode_64_safe(&p, end, server_feat, bad);
        ceph_decode_64_safe(&p, end, server_req_feat, bad);

        dout("%s con %p server_feat 0x%llx server_req_feat 0x%llx\n",
             __func__, con, server_feat, server_req_feat);

        if (req_feat & ~server_feat) {
                pr_err("msgr2 feature set mismatch: my required > server's supported 0x%llx, need 0x%llx\n",
                       server_feat, req_feat & ~server_feat);
                con->error_msg = "missing required protocol features";
                return -EINVAL;
        }
        if (server_req_feat & ~feat) {
                pr_err("msgr2 feature set mismatch: server's required > my supported 0x%llx, missing 0x%llx\n",
                       feat, server_req_feat & ~feat);
                con->error_msg = "missing required protocol features";
                return -EINVAL;
        }

        /* no reset_out_kvecs() as our banner may still be pending */
        ret = prepare_hello(con);
        if (ret) {
                pr_err("prepare_hello failed: %d\n", ret);
                return ret;
        }

        con->state = CEPH_CON_S_V2_HELLO;
        prepare_read_preamble(con);
        return 0;

bad:
        pr_err("failed to decode banner payload\n");
        return -EINVAL;
}

static int process_hello(struct ceph_connection *con, void *p, void *end)
{
        struct ceph_entity_addr *my_addr = &con->msgr->inst.addr;
        struct ceph_entity_addr addr_for_me;
        u8 entity_type;
        int ret;

        if (con->state != CEPH_CON_S_V2_HELLO) {
                con->error_msg = "protocol error, unexpected hello";
                return -EINVAL;
        }

        ceph_decode_8_safe(&p, end, entity_type, bad);
        ret = ceph_decode_entity_addr(&p, end, &addr_for_me);
        if (ret) {
                pr_err("failed to decode addr_for_me: %d\n", ret);
                return ret;
        }

        dout("%s con %p entity_type %d addr_for_me %s\n", __func__, con,
             entity_type, ceph_pr_addr(&addr_for_me));

        if (entity_type != con->peer_name.type) {
                pr_err("bad peer type, want %d, got %d\n",
                       con->peer_name.type, entity_type);
                con->error_msg = "wrong peer at address";
                return -EINVAL;
        }

        /*
         * Set our address to the address our first peer (i.e. monitor)
         * sees that we are connecting from.  If we are behind some sort
         * of NAT and want to be identified by some private (not NATed)
         * address, ip option should be used.
         */
        if (ceph_addr_is_blank(my_addr)) {
                memcpy(&my_addr->in_addr, &addr_for_me.in_addr,
                       sizeof(my_addr->in_addr));
                ceph_addr_set_port(my_addr, 0);
                dout("%s con %p set my addr %s, as seen by peer %s\n",
                     __func__, con, ceph_pr_addr(my_addr),
                     ceph_pr_addr(&con->peer_addr));
        } else {
                dout("%s con %p my addr already set %s\n",
                     __func__, con, ceph_pr_addr(my_addr));
        }

        WARN_ON(ceph_addr_is_blank(my_addr) || ceph_addr_port(my_addr));
        WARN_ON(my_addr->type != CEPH_ENTITY_ADDR_TYPE_ANY);
        WARN_ON(!my_addr->nonce);

        /* no reset_out_kvecs() as our hello may still be pending */
        ret = prepare_auth_request(con);
        if (ret) {
                if (ret != -EAGAIN)
                        pr_err("prepare_auth_request failed: %d\n", ret);
                return ret;
        }

        con->state = CEPH_CON_S_V2_AUTH;
        return 0;

bad:
        pr_err("failed to decode hello\n");
        return -EINVAL;
}

static int process_auth_bad_method(struct ceph_connection *con,
                                   void *p, void *end)
{
        int allowed_protos[8], allowed_modes[8];
        int allowed_proto_cnt, allowed_mode_cnt;
        int used_proto, result;
        int ret;
        int i;

        if (con->state != CEPH_CON_S_V2_AUTH) {
                con->error_msg = "protocol error, unexpected auth_bad_method";
                return -EINVAL;
        }

        ceph_decode_32_safe(&p, end, used_proto, bad);
        ceph_decode_32_safe(&p, end, result, bad);
        dout("%s con %p used_proto %d result %d\n", __func__, con, used_proto,
             result);

        ceph_decode_32_safe(&p, end, allowed_proto_cnt, bad);
        if (allowed_proto_cnt > ARRAY_SIZE(allowed_protos)) {
                pr_err("allowed_protos too big %d\n", allowed_proto_cnt);
                return -EINVAL;
        }
        for (i = 0; i < allowed_proto_cnt; i++) {
                ceph_decode_32_safe(&p, end, allowed_protos[i], bad);
                dout("%s con %p allowed_protos[%d] %d\n", __func__, con,
                     i, allowed_protos[i]);
        }

        ceph_decode_32_safe(&p, end, allowed_mode_cnt, bad);
        if (allowed_mode_cnt > ARRAY_SIZE(allowed_modes)) {
                pr_err("allowed_modes too big %d\n", allowed_mode_cnt);
                return -EINVAL;
        }
        for (i = 0; i < allowed_mode_cnt; i++) {
                ceph_decode_32_safe(&p, end, allowed_modes[i], bad);
                dout("%s con %p allowed_modes[%d] %d\n", __func__, con,
                     i, allowed_modes[i]);
        }

        mutex_unlock(&con->mutex);
        ret = con->ops->handle_auth_bad_method(con, used_proto, result,
                                               allowed_protos,
                                               allowed_proto_cnt,
                                               allowed_modes,
                                               allowed_mode_cnt);
        mutex_lock(&con->mutex);
        if (con->state != CEPH_CON_S_V2_AUTH) {
                dout("%s con %p state changed to %d\n", __func__, con,
                     con->state);
                return -EAGAIN;
        }

        dout("%s con %p handle_auth_bad_method ret %d\n", __func__, con, ret);
        return ret;

bad:

        pr_err("failed to decode auth_bad_method\n");
        return -EINVAL;
}

static int process_auth_reply_more(struct ceph_connection *con,
                                   void *p, void *end)
{
        int payload_len;
        int ret;

        if (con->state != CEPH_CON_S_V2_AUTH) {
                con->error_msg = "protocol error, unexpected auth_reply_more";
                return -EINVAL;
        }

        ceph_decode_32_safe(&p, end, payload_len, bad);
        ceph_decode_need(&p, end, payload_len, bad);

        dout("%s con %p payload_len %d\n", __func__, con, payload_len);

        reset_out_kvecs(con);
        ret = prepare_auth_request_more(con, p, payload_len);
        if (ret) {
                if (ret != -EAGAIN)
                        pr_err("prepare_auth_request_more failed: %d\n", ret);
                return ret;
        }

        return 0;

bad:
        pr_err("failed to decode auth_reply_more\n");
        return -EINVAL;
}

/*
 * Align session_key and con_secret to avoid GFP_ATOMIC allocation
 * inside crypto_shash_setkey() and crypto_aead_setkey() called from
 * setup_crypto().  __aligned(16) isn't guaranteed to work for stack
 * objects, so do it by hand.
 */
static int process_auth_done(struct ceph_connection *con, void *p, void *end)
{
        u8 session_key_buf[CEPH_KEY_LEN + 16];
        u8 con_secret_buf[CEPH_MAX_CON_SECRET_LEN + 16];
        u8 *session_key = PTR_ALIGN(&session_key_buf[0], 16);
        u8 *con_secret = PTR_ALIGN(&con_secret_buf[0], 16);
        int session_key_len, con_secret_len;
        int payload_len;
        u64 global_id;
        int ret;

        if (con->state != CEPH_CON_S_V2_AUTH) {
                con->error_msg = "protocol error, unexpected auth_done";
                return -EINVAL;
        }

        ceph_decode_64_safe(&p, end, global_id, bad);
        ceph_decode_32_safe(&p, end, con->v2.con_mode, bad);
        ceph_decode_32_safe(&p, end, payload_len, bad);

        dout("%s con %p global_id %llu con_mode %d payload_len %d\n",
             __func__, con, global_id, con->v2.con_mode, payload_len);

        mutex_unlock(&con->mutex);
        session_key_len = 0;
        con_secret_len = 0;
        ret = con->ops->handle_auth_done(con, global_id, p, payload_len,
                                         session_key, &session_key_len,
                                         con_secret, &con_secret_len);
        mutex_lock(&con->mutex);
        if (con->state != CEPH_CON_S_V2_AUTH) {
                dout("%s con %p state changed to %d\n", __func__, con,
                     con->state);
                ret = -EAGAIN;
                goto out;
        }

        dout("%s con %p handle_auth_done ret %d\n", __func__, con, ret);
        if (ret)
                goto out;

        ret = setup_crypto(con, session_key, session_key_len, con_secret,
                           con_secret_len);
        if (ret)
                goto out;

        reset_out_kvecs(con);
        ret = prepare_auth_signature(con);
        if (ret) {
                pr_err("prepare_auth_signature failed: %d\n", ret);
                goto out;
        }

        con->state = CEPH_CON_S_V2_AUTH_SIGNATURE;

out:
        memzero_explicit(session_key_buf, sizeof(session_key_buf));
        memzero_explicit(con_secret_buf, sizeof(con_secret_buf));
        return ret;

bad:
        pr_err("failed to decode auth_done\n");
        return -EINVAL;
}

static int process_auth_signature(struct ceph_connection *con,
                                  void *p, void *end)
{
        u8 hmac[SHA256_DIGEST_SIZE];
        int ret;

        if (con->state != CEPH_CON_S_V2_AUTH_SIGNATURE) {
                con->error_msg = "protocol error, unexpected auth_signature";
                return -EINVAL;
        }

        ret = hmac_sha256(con, con->v2.out_sign_kvecs,
                          con->v2.out_sign_kvec_cnt, hmac);
        if (ret)
                return ret;

        ceph_decode_need(&p, end, SHA256_DIGEST_SIZE, bad);
        if (crypto_memneq(p, hmac, SHA256_DIGEST_SIZE)) {
                con->error_msg = "integrity error, bad auth signature";
                return -EBADMSG;
        }

        dout("%s con %p auth signature ok\n", __func__, con);

        /* no reset_out_kvecs() as our auth_signature may still be pending */
        if (!con->v2.server_cookie) {
                ret = prepare_client_ident(con);
                if (ret) {
                        pr_err("prepare_client_ident failed: %d\n", ret);
                        return ret;
                }

                con->state = CEPH_CON_S_V2_SESSION_CONNECT;
        } else {
                ret = prepare_session_reconnect(con);
                if (ret) {
                        pr_err("prepare_session_reconnect failed: %d\n", ret);
                        return ret;
                }

                con->state = CEPH_CON_S_V2_SESSION_RECONNECT;
        }

        return 0;

bad:
        pr_err("failed to decode auth_signature\n");
        return -EINVAL;
}

static int process_server_ident(struct ceph_connection *con,
                                void *p, void *end)
{
        struct ceph_client *client = from_msgr(con->msgr);
        u64 features, required_features;
        struct ceph_entity_addr addr;
        u64 global_seq;
        u64 global_id;
        u64 cookie;
        u64 flags;
        int ret;

        if (con->state != CEPH_CON_S_V2_SESSION_CONNECT) {
                con->error_msg = "protocol error, unexpected server_ident";
                return -EINVAL;
        }

        ret = ceph_decode_entity_addrvec(&p, end, true, &addr);
        if (ret) {
                pr_err("failed to decode server addrs: %d\n", ret);
                return ret;
        }

        ceph_decode_64_safe(&p, end, global_id, bad);
        ceph_decode_64_safe(&p, end, global_seq, bad);
        ceph_decode_64_safe(&p, end, features, bad);
        ceph_decode_64_safe(&p, end, required_features, bad);
        ceph_decode_64_safe(&p, end, flags, bad);
        ceph_decode_64_safe(&p, end, cookie, bad);

        dout("%s con %p addr %s/%u global_id %llu global_seq %llu features 0x%llx required_features 0x%llx flags 0x%llx cookie 0x%llx\n",
             __func__, con, ceph_pr_addr(&addr), le32_to_cpu(addr.nonce),
             global_id, global_seq, features, required_features, flags, cookie);

        /* is this who we intended to talk to? */
        if (memcmp(&addr, &con->peer_addr, sizeof(con->peer_addr))) {
                pr_err("bad peer addr/nonce, want %s/%u, got %s/%u\n",
                       ceph_pr_addr(&con->peer_addr),
                       le32_to_cpu(con->peer_addr.nonce),
                       ceph_pr_addr(&addr), le32_to_cpu(addr.nonce));
                con->error_msg = "wrong peer at address";
                return -EINVAL;
        }

        if (client->required_features & ~features) {
                pr_err("RADOS feature set mismatch: my required > server's supported 0x%llx, need 0x%llx\n",
                       features, client->required_features & ~features);
                con->error_msg = "missing required protocol features";
                return -EINVAL;
        }

        /*
         * Both name->type and name->num are set in ceph_con_open() but
         * name->num may be bogus in the initial monmap.  name->type is
         * verified in handle_hello().
         */
        WARN_ON(!con->peer_name.type);
        con->peer_name.num = cpu_to_le64(global_id);
        con->v2.peer_global_seq = global_seq;
        con->peer_features = features;
        WARN_ON(required_features & ~client->supported_features);
        con->v2.server_cookie = cookie;

        if (flags & CEPH_MSG_CONNECT_LOSSY) {
                ceph_con_flag_set(con, CEPH_CON_F_LOSSYTX);
                WARN_ON(con->v2.server_cookie);
        } else {
                WARN_ON(!con->v2.server_cookie);
        }

        clear_in_sign_kvecs(con);
        clear_out_sign_kvecs(con);
        free_conn_bufs(con);
        con->delay = 0;  /* reset backoff memory */

        con->state = CEPH_CON_S_OPEN;
        con->v2.out_state = OUT_S_GET_NEXT;
        return 0;

bad:
        pr_err("failed to decode server_ident\n");
        return -EINVAL;
}

static int process_ident_missing_features(struct ceph_connection *con,
                                          void *p, void *end)
{
        struct ceph_client *client = from_msgr(con->msgr);
        u64 missing_features;

        if (con->state != CEPH_CON_S_V2_SESSION_CONNECT) {
                con->error_msg = "protocol error, unexpected ident_missing_features";
                return -EINVAL;
        }

        ceph_decode_64_safe(&p, end, missing_features, bad);
        pr_err("RADOS feature set mismatch: server's required > my supported 0x%llx, missing 0x%llx\n",
               client->supported_features, missing_features);
        con->error_msg = "missing required protocol features";
        return -EINVAL;

bad:
        pr_err("failed to decode ident_missing_features\n");
        return -EINVAL;
}

static int process_session_reconnect_ok(struct ceph_connection *con,
                                        void *p, void *end)
{
        u64 seq;

        if (con->state != CEPH_CON_S_V2_SESSION_RECONNECT) {
                con->error_msg = "protocol error, unexpected session_reconnect_ok";
                return -EINVAL;
        }

        ceph_decode_64_safe(&p, end, seq, bad);

        dout("%s con %p seq %llu\n", __func__, con, seq);
        ceph_con_discard_requeued(con, seq);

        clear_in_sign_kvecs(con);
        clear_out_sign_kvecs(con);
        free_conn_bufs(con);
        con->delay = 0;  /* reset backoff memory */

        con->state = CEPH_CON_S_OPEN;
        con->v2.out_state = OUT_S_GET_NEXT;
        return 0;

bad:
        pr_err("failed to decode session_reconnect_ok\n");
        return -EINVAL;
}

static int process_session_retry(struct ceph_connection *con,
                                 void *p, void *end)
{
        u64 connect_seq;
        int ret;

        if (con->state != CEPH_CON_S_V2_SESSION_RECONNECT) {
                con->error_msg = "protocol error, unexpected session_retry";
                return -EINVAL;
        }

        ceph_decode_64_safe(&p, end, connect_seq, bad);

        dout("%s con %p connect_seq %llu\n", __func__, con, connect_seq);
        WARN_ON(connect_seq <= con->v2.connect_seq);
        con->v2.connect_seq = connect_seq + 1;

        free_conn_bufs(con);

        reset_out_kvecs(con);
        ret = prepare_session_reconnect(con);
        if (ret) {
                pr_err("prepare_session_reconnect (cseq) failed: %d\n", ret);
                return ret;
        }

        return 0;

bad:
        pr_err("failed to decode session_retry\n");
        return -EINVAL;
}

static int process_session_retry_global(struct ceph_connection *con,
                                        void *p, void *end)
{
        u64 global_seq;
        int ret;

        if (con->state != CEPH_CON_S_V2_SESSION_RECONNECT) {
                con->error_msg = "protocol error, unexpected session_retry_global";
                return -EINVAL;
        }

        ceph_decode_64_safe(&p, end, global_seq, bad);

        dout("%s con %p global_seq %llu\n", __func__, con, global_seq);
        WARN_ON(global_seq <= con->v2.global_seq);
        con->v2.global_seq = ceph_get_global_seq(con->msgr, global_seq);

        free_conn_bufs(con);

        reset_out_kvecs(con);
        ret = prepare_session_reconnect(con);
        if (ret) {
                pr_err("prepare_session_reconnect (gseq) failed: %d\n", ret);
                return ret;
        }

        return 0;

bad:
        pr_err("failed to decode session_retry_global\n");
        return -EINVAL;
}

static int process_session_reset(struct ceph_connection *con,
                                 void *p, void *end)
{
        bool full;
        int ret;

        if (con->state != CEPH_CON_S_V2_SESSION_RECONNECT) {
                con->error_msg = "protocol error, unexpected session_reset";
                return -EINVAL;
        }

        ceph_decode_8_safe(&p, end, full, bad);
        if (!full) {
                con->error_msg = "protocol error, bad session_reset";
                return -EINVAL;
        }

        pr_info("%s%lld %s session reset\n", ENTITY_NAME(con->peer_name),
                ceph_pr_addr(&con->peer_addr));
        ceph_con_reset_session(con);

        mutex_unlock(&con->mutex);
        if (con->ops->peer_reset)
                con->ops->peer_reset(con);
        mutex_lock(&con->mutex);
        if (con->state != CEPH_CON_S_V2_SESSION_RECONNECT) {
                dout("%s con %p state changed to %d\n", __func__, con,
                     con->state);
                return -EAGAIN;
        }

        free_conn_bufs(con);

        reset_out_kvecs(con);
        ret = prepare_client_ident(con);
        if (ret) {
                pr_err("prepare_client_ident (rst) failed: %d\n", ret);
                return ret;
        }

        con->state = CEPH_CON_S_V2_SESSION_CONNECT;
        return 0;

bad:
        pr_err("failed to decode session_reset\n");
        return -EINVAL;
}

static int process_keepalive2_ack(struct ceph_connection *con,
                                  void *p, void *end)
{
        if (con->state != CEPH_CON_S_OPEN) {
                con->error_msg = "protocol error, unexpected keepalive2_ack";
                return -EINVAL;
        }

        ceph_decode_need(&p, end, sizeof(struct ceph_timespec), bad);
        ceph_decode_timespec64(&con->last_keepalive_ack, p);

        dout("%s con %p timestamp %lld.%09ld\n", __func__, con,
             con->last_keepalive_ack.tv_sec, con->last_keepalive_ack.tv_nsec);

        return 0;

bad:
        pr_err("failed to decode keepalive2_ack\n");
        return -EINVAL;
}

static int process_ack(struct ceph_connection *con, void *p, void *end)
{
        u64 seq;

        if (con->state != CEPH_CON_S_OPEN) {
                con->error_msg = "protocol error, unexpected ack";
                return -EINVAL;
        }

        ceph_decode_64_safe(&p, end, seq, bad);

        dout("%s con %p seq %llu\n", __func__, con, seq);
        ceph_con_discard_sent(con, seq);
        return 0;

bad:
        pr_err("failed to decode ack\n");
        return -EINVAL;
}

static int process_control(struct ceph_connection *con, void *p, void *end)
{
        int tag = con->v2.in_desc.fd_tag;
        int ret;

        dout("%s con %p tag %d len %d\n", __func__, con, tag, (int)(end - p));

        switch (tag) {
        case FRAME_TAG_HELLO:
                ret = process_hello(con, p, end);
                break;
        case FRAME_TAG_AUTH_BAD_METHOD:
                ret = process_auth_bad_method(con, p, end);
                break;
        case FRAME_TAG_AUTH_REPLY_MORE:
                ret = process_auth_reply_more(con, p, end);
                break;
        case FRAME_TAG_AUTH_DONE:
                ret = process_auth_done(con, p, end);
                break;
        case FRAME_TAG_AUTH_SIGNATURE:
                ret = process_auth_signature(con, p, end);
                break;
        case FRAME_TAG_SERVER_IDENT:
                ret = process_server_ident(con, p, end);
                break;
        case FRAME_TAG_IDENT_MISSING_FEATURES:
                ret = process_ident_missing_features(con, p, end);
                break;
        case FRAME_TAG_SESSION_RECONNECT_OK:
                ret = process_session_reconnect_ok(con, p, end);
                break;
        case FRAME_TAG_SESSION_RETRY:
                ret = process_session_retry(con, p, end);
                break;
        case FRAME_TAG_SESSION_RETRY_GLOBAL:
                ret = process_session_retry_global(con, p, end);
                break;
        case FRAME_TAG_SESSION_RESET:
                ret = process_session_reset(con, p, end);
                break;
        case FRAME_TAG_KEEPALIVE2_ACK:
                ret = process_keepalive2_ack(con, p, end);
                break;
        case FRAME_TAG_ACK:
                ret = process_ack(con, p, end);
                break;
        default:
                pr_err("bad tag %d\n", tag);
                con->error_msg = "protocol error, bad tag";
                return -EINVAL;
        }
        if (ret) {
                dout("%s con %p error %d\n", __func__, con, ret);
                return ret;
        }

        prepare_read_preamble(con);
        return 0;
}

/*
 * Return:
 *   1 - con->in_msg set, read message
 *   0 - skip message
 *  <0 - error
 */
static int process_message_header(struct ceph_connection *con,
                                  void *p, void *end)
{
        struct ceph_frame_desc *desc = &con->v2.in_desc;
        struct ceph_msg_header2 *hdr2 = p;
        struct ceph_msg_header hdr;
        int skip;
        int ret;
        u64 seq;

        /* verify seq# */
        seq = le64_to_cpu(hdr2->seq);
        if ((s64)seq - (s64)con->in_seq < 1) {
                pr_info("%s%lld %s skipping old message: seq %llu, expected %llu\n",
                        ENTITY_NAME(con->peer_name),
                        ceph_pr_addr(&con->peer_addr),
                        seq, con->in_seq + 1);
                return 0;
        }
        if ((s64)seq - (s64)con->in_seq > 1) {
                pr_err("bad seq %llu, expected %llu\n", seq, con->in_seq + 1);
                con->error_msg = "bad message sequence # for incoming message";
                return -EBADE;
        }

        ceph_con_discard_sent(con, le64_to_cpu(hdr2->ack_seq));

        fill_header(&hdr, hdr2, desc->fd_lens[1], desc->fd_lens[2],
                    desc->fd_lens[3], &con->peer_name);
        ret = ceph_con_in_msg_alloc(con, &hdr, &skip);
        if (ret)
                return ret;

        WARN_ON(!con->in_msg ^ skip);
        if (skip)
                return 0;

        WARN_ON(!con->in_msg);
        WARN_ON(con->in_msg->con != con);
        return 1;
}

static int process_message(struct ceph_connection *con)
{
        ceph_con_process_message(con);

        /*
         * We could have been closed by ceph_con_close() because
         * ceph_con_process_message() temporarily drops con->mutex.
         */
        if (con->state != CEPH_CON_S_OPEN) {
                dout("%s con %p state changed to %d\n", __func__, con,
                     con->state);
                return -EAGAIN;
        }

        prepare_read_preamble(con);
        return 0;
}

static int __handle_control(struct ceph_connection *con, void *p)
{
        void *end = p + con->v2.in_desc.fd_lens[0];
        struct ceph_msg *msg;
        int ret;

        if (con->v2.in_desc.fd_tag != FRAME_TAG_MESSAGE)
                return process_control(con, p, end);

        ret = process_message_header(con, p, end);
        if (ret < 0)
                return ret;
        if (ret == 0) {
                prepare_skip_message(con);
                return 0;
        }

        msg = con->in_msg;  /* set in process_message_header() */
        if (!front_len(msg) && !middle_len(msg)) {
                if (!data_len(msg))
                        return process_message(con);

                prepare_read_data(con);
                return 0;
        }

        reset_in_kvecs(con);
        if (front_len(msg)) {
                WARN_ON(front_len(msg) > msg->front_alloc_len);
                add_in_kvec(con, msg->front.iov_base, front_len(msg));
                msg->front.iov_len = front_len(msg);

                if (con_secure(con) && need_padding(front_len(msg)))
                        add_in_kvec(con, FRONT_PAD(con->v2.in_buf),
                                    padding_len(front_len(msg)));
        } else {
                msg->front.iov_len = 0;
        }
        if (middle_len(msg)) {
                WARN_ON(middle_len(msg) > msg->middle->alloc_len);
                add_in_kvec(con, msg->middle->vec.iov_base, middle_len(msg));
                msg->middle->vec.iov_len = middle_len(msg);

                if (con_secure(con) && need_padding(middle_len(msg)))
                        add_in_kvec(con, MIDDLE_PAD(con->v2.in_buf),
                                    padding_len(middle_len(msg)));
        } else if (msg->middle) {
                msg->middle->vec.iov_len = 0;
        }

        if (data_len(msg)) {
                con->v2.in_state = IN_S_PREPARE_READ_DATA;
        } else {
                add_in_kvec(con, con->v2.in_buf,
                            con_secure(con) ? CEPH_EPILOGUE_SECURE_LEN :
                                              CEPH_EPILOGUE_PLAIN_LEN);
                con->v2.in_state = IN_S_HANDLE_EPILOGUE;
        }
        return 0;
}

static int handle_preamble(struct ceph_connection *con)
{
        struct ceph_frame_desc *desc = &con->v2.in_desc;
        int ret;

        if (con_secure(con)) {
                ret = decrypt_preamble(con);
                if (ret) {
                        if (ret == -EBADMSG)
                                con->error_msg = "integrity error, bad preamble auth tag";
                        return ret;
                }
        }

        ret = decode_preamble(con->v2.in_buf, desc);
        if (ret) {
                if (ret == -EBADMSG)
                        con->error_msg = "integrity error, bad crc";
                else
                        con->error_msg = "protocol error, bad preamble";
                return ret;
        }

        dout("%s con %p tag %d seg_cnt %d %d+%d+%d+%d\n", __func__,
             con, desc->fd_tag, desc->fd_seg_cnt, desc->fd_lens[0],
             desc->fd_lens[1], desc->fd_lens[2], desc->fd_lens[3]);

        if (!con_secure(con))
                return prepare_read_control(con);

        if (desc->fd_lens[0] > CEPH_PREAMBLE_INLINE_LEN)
                return prepare_read_control_remainder(con);

        return __handle_control(con, CTRL_BODY(con->v2.in_buf));
}

static int handle_control(struct ceph_connection *con)
{
        int ctrl_len = con->v2.in_desc.fd_lens[0];
        void *buf;
        int ret;

        WARN_ON(con_secure(con));

        ret = verify_control_crc(con);
        if (ret) {
                con->error_msg = "integrity error, bad crc";
                return ret;
        }

        if (con->state == CEPH_CON_S_V2_AUTH) {
                buf = alloc_conn_buf(con, ctrl_len);
                if (!buf)
                        return -ENOMEM;

                memcpy(buf, con->v2.in_kvecs[0].iov_base, ctrl_len);
                return __handle_control(con, buf);
        }

        return __handle_control(con, con->v2.in_kvecs[0].iov_base);
}

static int handle_control_remainder(struct ceph_connection *con)
{
        int ret;

        WARN_ON(!con_secure(con));

        ret = decrypt_control_remainder(con);
        if (ret) {
                if (ret == -EBADMSG)
                        con->error_msg = "integrity error, bad control remainder auth tag";
                return ret;
        }

        return __handle_control(con, con->v2.in_kvecs[0].iov_base -
                                     CEPH_PREAMBLE_INLINE_LEN);
}

static int handle_epilogue(struct ceph_connection *con)
{
        u32 front_crc, middle_crc, data_crc;
        int ret;

        if (con_secure(con)) {
                ret = decrypt_message(con);
                if (ret) {
                        if (ret == -EBADMSG)
                                con->error_msg = "integrity error, bad epilogue auth tag";
                        return ret;
                }

                /* just late_status */
                ret = decode_epilogue(con->v2.in_buf, NULL, NULL, NULL);
                if (ret) {
                        con->error_msg = "protocol error, bad epilogue";
                        return ret;
                }
        } else {
                ret = decode_epilogue(con->v2.in_buf, &front_crc,
                                      &middle_crc, &data_crc);
                if (ret) {
                        con->error_msg = "protocol error, bad epilogue";
                        return ret;
                }

                ret = verify_epilogue_crcs(con, front_crc, middle_crc,
                                           data_crc);
                if (ret) {
                        con->error_msg = "integrity error, bad crc";
                        return ret;
                }
        }

        return process_message(con);
}

static void finish_skip(struct ceph_connection *con)
{
        dout("%s con %p\n", __func__, con);

        if (con_secure(con))
                gcm_inc_nonce(&con->v2.in_gcm_nonce);

        __finish_skip(con);
}

static int populate_in_iter(struct ceph_connection *con)
{
        int ret;

        dout("%s con %p state %d in_state %d\n", __func__, con, con->state,
             con->v2.in_state);
        WARN_ON(iov_iter_count(&con->v2.in_iter));

        if (con->state == CEPH_CON_S_V2_BANNER_PREFIX) {
                ret = process_banner_prefix(con);
        } else if (con->state == CEPH_CON_S_V2_BANNER_PAYLOAD) {
                ret = process_banner_payload(con);
        } else if ((con->state >= CEPH_CON_S_V2_HELLO &&
                    con->state <= CEPH_CON_S_V2_SESSION_RECONNECT) ||
                   con->state == CEPH_CON_S_OPEN) {
                switch (con->v2.in_state) {
                case IN_S_HANDLE_PREAMBLE:
                        ret = handle_preamble(con);
                        break;
                case IN_S_HANDLE_CONTROL:
                        ret = handle_control(con);
                        break;
                case IN_S_HANDLE_CONTROL_REMAINDER:
                        ret = handle_control_remainder(con);
                        break;
                case IN_S_PREPARE_READ_DATA:
                        prepare_read_data(con);
                        ret = 0;
                        break;
                case IN_S_PREPARE_READ_DATA_CONT:
                        prepare_read_data_cont(con);
                        ret = 0;
                        break;
                case IN_S_HANDLE_EPILOGUE:
                        ret = handle_epilogue(con);
                        break;
                case IN_S_FINISH_SKIP:
                        finish_skip(con);
                        ret = 0;
                        break;
                default:
                        WARN(1, "bad in_state %d", con->v2.in_state);
                        return -EINVAL;
                }
        } else {
                WARN(1, "bad state %d", con->state);
                return -EINVAL;
        }
        if (ret) {
                dout("%s con %p error %d\n", __func__, con, ret);
                return ret;
        }

        if (WARN_ON(!iov_iter_count(&con->v2.in_iter)))
                return -ENODATA;
        dout("%s con %p populated %zu\n", __func__, con,
             iov_iter_count(&con->v2.in_iter));
        return 1;
}

int ceph_con_v2_try_read(struct ceph_connection *con)
{
        int ret;

        dout("%s con %p state %d need %zu\n", __func__, con, con->state,
             iov_iter_count(&con->v2.in_iter));

        if (con->state == CEPH_CON_S_PREOPEN)
                return 0;

        /*
         * We should always have something pending here.  If not,
         * avoid calling populate_in_iter() as if we read something
         * (ceph_tcp_recv() would immediately return 1).
         */
        if (WARN_ON(!iov_iter_count(&con->v2.in_iter)))
                return -ENODATA;

        for (;;) {
                ret = ceph_tcp_recv(con);
                if (ret <= 0)
                        return ret;

                ret = populate_in_iter(con);
                if (ret <= 0) {
                        if (ret && ret != -EAGAIN && !con->error_msg)
                                con->error_msg = "read processing error";
                        return ret;
                }
        }
}

static void queue_data(struct ceph_connection *con)
{
        struct bio_vec bv;

        con->v2.out_epil.data_crc = -1;
        ceph_msg_data_cursor_init(&con->v2.out_cursor, con->out_msg,
                                  data_len(con->out_msg));

        get_bvec_at(&con->v2.out_cursor, &bv);
        set_out_bvec(con, &bv, true);
        con->v2.out_state = OUT_S_QUEUE_DATA_CONT;
}

static void queue_data_cont(struct ceph_connection *con)
{
        struct bio_vec bv;

        con->v2.out_epil.data_crc = ceph_crc32c_page(
                con->v2.out_epil.data_crc, con->v2.out_bvec.bv_page,
                con->v2.out_bvec.bv_offset, con->v2.out_bvec.bv_len);

        ceph_msg_data_advance(&con->v2.out_cursor, con->v2.out_bvec.bv_len);
        if (con->v2.out_cursor.total_resid) {
                get_bvec_at(&con->v2.out_cursor, &bv);
                set_out_bvec(con, &bv, true);
                WARN_ON(con->v2.out_state != OUT_S_QUEUE_DATA_CONT);
                return;
        }

        /*
         * We've written all data.  Queue epilogue.  Once it's written,
         * we are done.
         */
        reset_out_kvecs(con);
        prepare_epilogue_plain(con, false);
        con->v2.out_state = OUT_S_FINISH_MESSAGE;
}

static void queue_enc_page(struct ceph_connection *con)
{
        struct bio_vec bv;

        dout("%s con %p i %d resid %d\n", __func__, con, con->v2.out_enc_i,
             con->v2.out_enc_resid);
        WARN_ON(!con->v2.out_enc_resid);

        bv.bv_page = con->v2.out_enc_pages[con->v2.out_enc_i];
        bv.bv_offset = 0;
        bv.bv_len = min(con->v2.out_enc_resid, (int)PAGE_SIZE);

        set_out_bvec(con, &bv, false);
        con->v2.out_enc_i++;
        con->v2.out_enc_resid -= bv.bv_len;

        if (con->v2.out_enc_resid) {
                WARN_ON(con->v2.out_state != OUT_S_QUEUE_ENC_PAGE);
                return;
        }

        /*
         * We've queued the last piece of ciphertext (ending with
         * epilogue) + auth tag.  Once it's written, we are done.
         */
        WARN_ON(con->v2.out_enc_i != con->v2.out_enc_page_cnt);
        con->v2.out_state = OUT_S_FINISH_MESSAGE;
}

static void queue_zeros(struct ceph_connection *con)
{
        dout("%s con %p out_zero %d\n", __func__, con, con->v2.out_zero);

        if (con->v2.out_zero) {
                set_out_bvec_zero(con);
                con->v2.out_zero -= con->v2.out_bvec.bv_len;
                con->v2.out_state = OUT_S_QUEUE_ZEROS;
                return;
        }

        /*
         * We've zero-filled everything up to epilogue.  Queue epilogue
         * with late_status set to ABORTED and crcs adjusted for zeros.
         * Once it's written, we are done patching up for the revoke.
         */
        reset_out_kvecs(con);
        prepare_epilogue_plain(con, true);
        con->v2.out_state = OUT_S_FINISH_MESSAGE;
}

static void finish_message(struct ceph_connection *con)
{
        dout("%s con %p msg %p\n", __func__, con, con->out_msg);

        /* we end up here both plain and secure modes */
        if (con->v2.out_enc_pages) {
                WARN_ON(!con->v2.out_enc_page_cnt);
                ceph_release_page_vector(con->v2.out_enc_pages,
                                         con->v2.out_enc_page_cnt);
                con->v2.out_enc_pages = NULL;
                con->v2.out_enc_page_cnt = 0;
        }
        /* message may have been revoked */
        if (con->out_msg) {
                ceph_msg_put(con->out_msg);
                con->out_msg = NULL;
        }

        con->v2.out_state = OUT_S_GET_NEXT;
}

static int populate_out_iter(struct ceph_connection *con)
{
        int ret;

        dout("%s con %p state %d out_state %d\n", __func__, con, con->state,
             con->v2.out_state);
        WARN_ON(iov_iter_count(&con->v2.out_iter));

        if (con->state != CEPH_CON_S_OPEN) {
                WARN_ON(con->state < CEPH_CON_S_V2_BANNER_PREFIX ||
                        con->state > CEPH_CON_S_V2_SESSION_RECONNECT);
                goto nothing_pending;
        }

        switch (con->v2.out_state) {
        case OUT_S_QUEUE_DATA:
                WARN_ON(!con->out_msg);
                queue_data(con);
                goto populated;
        case OUT_S_QUEUE_DATA_CONT:
                WARN_ON(!con->out_msg);
                queue_data_cont(con);
                goto populated;
        case OUT_S_QUEUE_ENC_PAGE:
                queue_enc_page(con);
                goto populated;
        case OUT_S_QUEUE_ZEROS:
                WARN_ON(con->out_msg);  /* revoked */
                queue_zeros(con);
                goto populated;
        case OUT_S_FINISH_MESSAGE:
                finish_message(con);
                break;
        case OUT_S_GET_NEXT:
                break;
        default:
                WARN(1, "bad out_state %d", con->v2.out_state);
                return -EINVAL;