// SPDX-License-Identifier: GPL-2.0-or-later
/*******************************************************************************
 * This file contains main functions related to iSCSI Parameter negotiation.
 *
 * (c) Copyright 2007-2013 Datera, Inc.
 *
 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
 *
 ******************************************************************************/

#include <linux/ctype.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <net/sock.h>
#include <trace/events/sock.h>
#include <scsi/iscsi_proto.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/iscsi/iscsi_transport.h>

#include <target/iscsi/iscsi_target_core.h>
#include "iscsi_target_parameters.h"
#include "iscsi_target_login.h"
#include "iscsi_target_nego.h"
#include "iscsi_target_tpg.h"
#include "iscsi_target_util.h"
#include "iscsi_target.h"
#include "iscsi_target_auth.h"

#define MAX_LOGIN_PDUS  7

void convert_null_to_semi(char *buf, int len)
{
        int i;

        for (i = 0; i < len; i++)
                if (buf[i] == '\0')
                        buf[i] = ';';
}

static int strlen_semi(char *buf)
{
        int i = 0;

        while (buf[i] != '\0') {
                if (buf[i] == ';')
                        return i;
                i++;
        }

        return -1;
}

int extract_param(
        const char *in_buf,
        const char *pattern,
        unsigned int max_length,
        char *out_buf,
        unsigned char *type)
{
        char *ptr;
        int len;

        if (!in_buf || !pattern || !out_buf || !type)
                return -EINVAL;

        ptr = strstr(in_buf, pattern);
        if (!ptr)
                return -ENOENT;

        ptr = strstr(ptr, "=");
        if (!ptr)
                return -EINVAL;

        ptr += 1;
        if (*ptr == '0' && (*(ptr+1) == 'x' || *(ptr+1) == 'X')) {
                ptr += 2; /* skip 0x */
                *type = HEX;
        } else if (*ptr == '0' && (*(ptr+1) == 'b' || *(ptr+1) == 'B')) {
                ptr += 2; /* skip 0b */
                *type = BASE64;
        } else
                *type = DECIMAL;

        len = strlen_semi(ptr);
        if (len < 0)
                return -EINVAL;

        if (len >= max_length) {
                pr_err("Length of input: %d exceeds max_length:"
                        " %d\n", len, max_length);
                return -EINVAL;
        }
        memcpy(out_buf, ptr, len);
        out_buf[len] = '\0';

        return 0;
}

static struct iscsi_node_auth *iscsi_get_node_auth(struct iscsit_conn *conn)
{
        struct iscsi_portal_group *tpg;
        struct iscsi_node_acl *nacl;
        struct se_node_acl *se_nacl;

        if (conn->sess->sess_ops->SessionType)
                return &iscsit_global->discovery_acl.node_auth;

        se_nacl = conn->sess->se_sess->se_node_acl;
        if (!se_nacl) {
                pr_err("Unable to locate struct se_node_acl for CHAP auth\n");
                return NULL;
        }

        if (se_nacl->dynamic_node_acl) {
                tpg = to_iscsi_tpg(se_nacl->se_tpg);
                return &tpg->tpg_demo_auth;
        }

        nacl = to_iscsi_nacl(se_nacl);

        return &nacl->node_auth;
}

static u32 iscsi_handle_authentication(
        struct iscsit_conn *conn,
        char *in_buf,
        char *out_buf,
        int in_length,
        int *out_length,
        unsigned char *authtype)
{
        struct iscsi_node_auth *auth;

        auth = iscsi_get_node_auth(conn);
        if (!auth)
                return -1;

        if (strstr("CHAP", authtype))
                strcpy(conn->sess->auth_type, "CHAP");
        else
                strcpy(conn->sess->auth_type, NONE);

        if (strstr("None", authtype))
                return 1;
        else if (strstr("CHAP", authtype))
                return chap_main_loop(conn, auth, in_buf, out_buf,
                                &in_length, out_length);
        /* SRP, SPKM1, SPKM2 and KRB5 are unsupported */
        return 2;
}

static void iscsi_remove_failed_auth_entry(struct iscsit_conn *conn)
{
        kfree(conn->auth_protocol);
}

int iscsi_target_check_login_request(
        struct iscsit_conn *conn,
        struct iscsi_login *login)
{
        int req_csg, req_nsg;
        u32 payload_length;
        struct iscsi_login_req *login_req;

        login_req = (struct iscsi_login_req *) login->req;
        payload_length = ntoh24(login_req->dlength);

        switch (login_req->opcode & ISCSI_OPCODE_MASK) {
        case ISCSI_OP_LOGIN:
                break;
        default:
                pr_err("Received unknown opcode 0x%02x.\n",
                                login_req->opcode & ISCSI_OPCODE_MASK);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if ((login_req->flags & ISCSI_FLAG_LOGIN_CONTINUE) &&
            (login_req->flags & ISCSI_FLAG_LOGIN_TRANSIT)) {
                pr_err("Login request has both ISCSI_FLAG_LOGIN_CONTINUE"
                        " and ISCSI_FLAG_LOGIN_TRANSIT set, protocol error.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        req_csg = ISCSI_LOGIN_CURRENT_STAGE(login_req->flags);
        req_nsg = ISCSI_LOGIN_NEXT_STAGE(login_req->flags);

        if (req_csg != login->current_stage) {
                pr_err("Initiator unexpectedly changed login stage"
                        " from %d to %d, login failed.\n", login->current_stage,
                        req_csg);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if ((req_nsg == 2) || (req_csg >= 2) ||
           ((login_req->flags & ISCSI_FLAG_LOGIN_TRANSIT) &&
            (req_nsg <= req_csg))) {
                pr_err("Illegal login_req->flags Combination, CSG: %d,"
                        " NSG: %d, ISCSI_FLAG_LOGIN_TRANSIT: %d.\n", req_csg,
                        req_nsg, (login_req->flags & ISCSI_FLAG_LOGIN_TRANSIT));
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if ((login_req->max_version != login->version_max) ||
            (login_req->min_version != login->version_min)) {
                pr_err("Login request changed Version Max/Min"
                        " unexpectedly to 0x%02x/0x%02x, protocol error\n",
                        login_req->max_version, login_req->min_version);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if (memcmp(login_req->isid, login->isid, 6) != 0) {
                pr_err("Login request changed ISID unexpectedly,"
                                " protocol error.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if (login_req->itt != login->init_task_tag) {
                pr_err("Login request changed ITT unexpectedly to"
                        " 0x%08x, protocol error.\n", login_req->itt);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if (payload_length > MAX_KEY_VALUE_PAIRS) {
                pr_err("Login request payload exceeds default"
                        " MaxRecvDataSegmentLength: %u, protocol error.\n",
                                MAX_KEY_VALUE_PAIRS);
                return -1;
        }

        return 0;
}
EXPORT_SYMBOL(iscsi_target_check_login_request);

static int iscsi_target_check_first_request(
        struct iscsit_conn *conn,
        struct iscsi_login *login)
{
        struct iscsi_param *param = NULL;
        struct se_node_acl *se_nacl;

        login->first_request = 0;

        list_for_each_entry(param, &conn->param_list->param_list, p_list) {
                if (!strncmp(param->name, SESSIONTYPE, 11)) {
                        if (!IS_PSTATE_ACCEPTOR(param)) {
                                pr_err("SessionType key not received"
                                        " in first login request.\n");
                                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                        ISCSI_LOGIN_STATUS_MISSING_FIELDS);
                                return -1;
                        }
                        if (!strncmp(param->value, DISCOVERY, 9))
                                return 0;
                }

                if (!strncmp(param->name, INITIATORNAME, 13)) {
                        if (!IS_PSTATE_ACCEPTOR(param)) {
                                if (!login->leading_connection)
                                        continue;

                                pr_err("InitiatorName key not received"
                                        " in first login request.\n");
                                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                        ISCSI_LOGIN_STATUS_MISSING_FIELDS);
                                return -1;
                        }

                        /*
                         * For non-leading connections, double check that the
                         * received InitiatorName matches the existing session's
                         * struct iscsi_node_acl.
                         */
                        if (!login->leading_connection) {
                                se_nacl = conn->sess->se_sess->se_node_acl;
                                if (!se_nacl) {
                                        pr_err("Unable to locate"
                                                " struct se_node_acl\n");
                                        iscsit_tx_login_rsp(conn,
                                                        ISCSI_STATUS_CLS_INITIATOR_ERR,
                                                        ISCSI_LOGIN_STATUS_TGT_NOT_FOUND);
                                        return -1;
                                }

                                if (strcmp(param->value,
                                                se_nacl->initiatorname)) {
                                        pr_err("Incorrect"
                                                " InitiatorName: %s for this"
                                                " iSCSI Initiator Node.\n",
                                                param->value);
                                        iscsit_tx_login_rsp(conn,
                                                        ISCSI_STATUS_CLS_INITIATOR_ERR,
                                                        ISCSI_LOGIN_STATUS_TGT_NOT_FOUND);
                                        return -1;
                                }
                        }
                }
        }

        return 0;
}

static int iscsi_target_do_tx_login_io(struct iscsit_conn *conn, struct iscsi_login *login)
{
        u32 padding = 0;
        struct iscsi_login_rsp *login_rsp;

        login_rsp = (struct iscsi_login_rsp *) login->rsp;

        login_rsp->opcode               = ISCSI_OP_LOGIN_RSP;
        hton24(login_rsp->dlength, login->rsp_length);
        memcpy(login_rsp->isid, login->isid, 6);
        login_rsp->tsih                 = cpu_to_be16(login->tsih);
        login_rsp->itt                  = login->init_task_tag;
        login_rsp->statsn               = cpu_to_be32(conn->stat_sn++);
        login_rsp->exp_cmdsn            = cpu_to_be32(conn->sess->exp_cmd_sn);
        login_rsp->max_cmdsn            = cpu_to_be32((u32) atomic_read(&conn->sess->max_cmd_sn));

        pr_debug("Sending Login Response, Flags: 0x%02x, ITT: 0x%08x,"
                " ExpCmdSN; 0x%08x, MaxCmdSN: 0x%08x, StatSN: 0x%08x, Length:"
                " %u\n", login_rsp->flags, (__force u32)login_rsp->itt,
                ntohl(login_rsp->exp_cmdsn), ntohl(login_rsp->max_cmdsn),
                ntohl(login_rsp->statsn), login->rsp_length);

        padding = ((-login->rsp_length) & 3);
        /*
         * Before sending the last login response containing the transition
         * bit for full-feature-phase, go ahead and start up TX/RX threads
         * now to avoid potential resource allocation failures after the
         * final login response has been sent.
         */
        if (login->login_complete) {
                int rc = iscsit_start_kthreads(conn);
                if (rc) {
                        iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                            ISCSI_LOGIN_STATUS_NO_RESOURCES);
                        return -1;
                }
        }

        if (conn->conn_transport->iscsit_put_login_tx(conn, login,
                                        login->rsp_length + padding) < 0)
                goto err;

        login->rsp_length               = 0;

        return 0;

err:
        if (login->login_complete) {
                if (conn->rx_thread && conn->rx_thread_active) {
                        send_sig(SIGINT, conn->rx_thread, 1);
                        complete(&conn->rx_login_comp);
                        kthread_stop(conn->rx_thread);
                }
                if (conn->tx_thread && conn->tx_thread_active) {
                        send_sig(SIGINT, conn->tx_thread, 1);
                        kthread_stop(conn->tx_thread);
                }
                spin_lock(&iscsit_global->ts_bitmap_lock);
                bitmap_release_region(iscsit_global->ts_bitmap, conn->bitmap_id,
                                      get_order(1));
                spin_unlock(&iscsit_global->ts_bitmap_lock);
        }
        return -1;
}

static void iscsi_target_sk_data_ready(struct sock *sk)
{
        struct iscsit_conn *conn = sk->sk_user_data;
        bool rc;

        trace_sk_data_ready(sk);
        pr_debug("Entering iscsi_target_sk_data_ready: conn: %p\n", conn);

        write_lock_bh(&sk->sk_callback_lock);
        if (!sk->sk_user_data) {
                write_unlock_bh(&sk->sk_callback_lock);
                return;
        }
        if (!test_bit(LOGIN_FLAGS_READY, &conn->login_flags)) {
                write_unlock_bh(&sk->sk_callback_lock);
                pr_debug("Got LOGIN_FLAGS_READY=0, conn: %p >>>>\n", conn);
                return;
        }
        if (test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags)) {
                write_unlock_bh(&sk->sk_callback_lock);
                pr_debug("Got LOGIN_FLAGS_CLOSED=1, conn: %p >>>>\n", conn);
                return;
        }
        if (test_and_set_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags)) {
                write_unlock_bh(&sk->sk_callback_lock);
                pr_debug("Got LOGIN_FLAGS_READ_ACTIVE=1, conn: %p >>>>\n", conn);
                if (iscsi_target_sk_data_ready == conn->orig_data_ready)
                        return;
                conn->orig_data_ready(sk);
                return;
        }

        rc = schedule_delayed_work(&conn->login_work, 0);
        if (!rc) {
                pr_debug("iscsi_target_sk_data_ready, schedule_delayed_work"
                         " got false\n");
        }
        write_unlock_bh(&sk->sk_callback_lock);
}

static void iscsi_target_sk_state_change(struct sock *);

static void iscsi_target_set_sock_callbacks(struct iscsit_conn *conn)
{
        struct sock *sk;

        if (!conn->sock)
                return;

        sk = conn->sock->sk;
        pr_debug("Entering iscsi_target_set_sock_callbacks: conn: %p\n", conn);

        write_lock_bh(&sk->sk_callback_lock);
        sk->sk_user_data = conn;
        conn->orig_data_ready = sk->sk_data_ready;
        conn->orig_state_change = sk->sk_state_change;
        sk->sk_data_ready = iscsi_target_sk_data_ready;
        sk->sk_state_change = iscsi_target_sk_state_change;
        write_unlock_bh(&sk->sk_callback_lock);

        sk->sk_sndtimeo = TA_LOGIN_TIMEOUT * HZ;
        sk->sk_rcvtimeo = TA_LOGIN_TIMEOUT * HZ;
}

static void iscsi_target_restore_sock_callbacks(struct iscsit_conn *conn)
{
        struct sock *sk;

        if (!conn->sock)
                return;

        sk = conn->sock->sk;
        pr_debug("Entering iscsi_target_restore_sock_callbacks: conn: %p\n", conn);

        write_lock_bh(&sk->sk_callback_lock);
        if (!sk->sk_user_data) {
                write_unlock_bh(&sk->sk_callback_lock);
                return;
        }
        sk->sk_user_data = NULL;
        sk->sk_data_ready = conn->orig_data_ready;
        sk->sk_state_change = conn->orig_state_change;
        write_unlock_bh(&sk->sk_callback_lock);

        sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
        sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;
}

static int iscsi_target_do_login(struct iscsit_conn *, struct iscsi_login *);

static bool __iscsi_target_sk_check_close(struct sock *sk)
{
        if (sk->sk_state == TCP_CLOSE_WAIT || sk->sk_state == TCP_CLOSE) {
                pr_debug("__iscsi_target_sk_check_close: TCP_CLOSE_WAIT|TCP_CLOSE,"
                        "returning TRUE\n");
                return true;
        }
        return false;
}

static bool iscsi_target_sk_check_close(struct iscsit_conn *conn)
{
        bool state = false;

        if (conn->sock) {
                struct sock *sk = conn->sock->sk;

                read_lock_bh(&sk->sk_callback_lock);
                state = (__iscsi_target_sk_check_close(sk) ||
                         test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags));
                read_unlock_bh(&sk->sk_callback_lock);
        }
        return state;
}

static bool iscsi_target_sk_check_flag(struct iscsit_conn *conn, unsigned int flag)
{
        bool state = false;

        if (conn->sock) {
                struct sock *sk = conn->sock->sk;

                read_lock_bh(&sk->sk_callback_lock);
                state = test_bit(flag, &conn->login_flags);
                read_unlock_bh(&sk->sk_callback_lock);
        }
        return state;
}

static bool iscsi_target_sk_check_and_clear(struct iscsit_conn *conn, unsigned int flag)
{
        bool state = false;

        if (conn->sock) {
                struct sock *sk = conn->sock->sk;

                write_lock_bh(&sk->sk_callback_lock);
                state = (__iscsi_target_sk_check_close(sk) ||
                         test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags));
                if (!state)
                        clear_bit(flag, &conn->login_flags);
                write_unlock_bh(&sk->sk_callback_lock);
        }
        return state;
}

static void iscsi_target_login_drop(struct iscsit_conn *conn, struct iscsi_login *login)
{
        bool zero_tsih = login->zero_tsih;

        iscsi_remove_failed_auth_entry(conn);
        iscsi_target_nego_release(conn);
        iscsi_target_login_sess_out(conn, zero_tsih, true);
}

static void iscsi_target_do_login_rx(struct work_struct *work)
{
        struct iscsit_conn *conn = container_of(work,
                                struct iscsit_conn, login_work.work);
        struct iscsi_login *login = conn->login;
        struct iscsi_np *np = login->np;
        struct iscsi_portal_group *tpg = conn->tpg;
        struct iscsi_tpg_np *tpg_np = conn->tpg_np;
        int rc, zero_tsih = login->zero_tsih;
        bool state;

        pr_debug("entering iscsi_target_do_login_rx, conn: %p, %s:%d\n",
                        conn, current->comm, current->pid);

        spin_lock(&conn->login_worker_lock);
        set_bit(LOGIN_FLAGS_WORKER_RUNNING, &conn->login_flags);
        spin_unlock(&conn->login_worker_lock);
        /*
         * If iscsi_target_do_login_rx() has been invoked by ->sk_data_ready()
         * before initial PDU processing in iscsi_target_start_negotiation()
         * has completed, go ahead and retry until it's cleared.
         *
         * Otherwise if the TCP connection drops while this is occurring,
         * iscsi_target_start_negotiation() will detect the failure, call
         * cancel_delayed_work_sync(&conn->login_work), and cleanup the
         * remaining iscsi connection resources from iscsi_np process context.
         */
        if (iscsi_target_sk_check_flag(conn, LOGIN_FLAGS_INITIAL_PDU)) {
                schedule_delayed_work(&conn->login_work, msecs_to_jiffies(10));
                return;
        }

        spin_lock(&tpg->tpg_state_lock);
        state = (tpg->tpg_state == TPG_STATE_ACTIVE);
        spin_unlock(&tpg->tpg_state_lock);

        if (!state) {
                pr_debug("iscsi_target_do_login_rx: tpg_state != TPG_STATE_ACTIVE\n");
                goto err;
        }

        if (iscsi_target_sk_check_close(conn)) {
                pr_debug("iscsi_target_do_login_rx, TCP state CLOSE\n");
                goto err;
        }

        allow_signal(SIGINT);
        rc = iscsit_set_login_timer_kworker(conn, current);
        if (rc < 0) {
                /* The login timer has already expired */
                pr_debug("iscsi_target_do_login_rx, login failed\n");
                goto err;
        }

        rc = conn->conn_transport->iscsit_get_login_rx(conn, login);
        flush_signals(current);

        if (rc < 0)
                goto err;

        pr_debug("iscsi_target_do_login_rx after rx_login_io, %p, %s:%d\n",
                        conn, current->comm, current->pid);

        /*
         * LOGIN_FLAGS_READ_ACTIVE is cleared so that sk_data_ready
         * could be triggered again after this.
         *
         * LOGIN_FLAGS_WRITE_ACTIVE is cleared after we successfully
         * process a login PDU, so that sk_state_chage can do login
         * cleanup as needed if the socket is closed. If a delayed work is
         * ongoing (LOGIN_FLAGS_WRITE_ACTIVE or LOGIN_FLAGS_READ_ACTIVE),
         * sk_state_change will leave the cleanup to the delayed work or
         * it will schedule a delayed work to do cleanup.
         */
        if (conn->sock) {
                struct sock *sk = conn->sock->sk;

                write_lock_bh(&sk->sk_callback_lock);
                if (!test_bit(LOGIN_FLAGS_INITIAL_PDU, &conn->login_flags)) {
                        clear_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags);
                        set_bit(LOGIN_FLAGS_WRITE_ACTIVE, &conn->login_flags);
                }
                write_unlock_bh(&sk->sk_callback_lock);
        }

        rc = iscsi_target_do_login(conn, login);
        if (rc < 0) {
                goto err;
        } else if (!rc) {
                if (iscsi_target_sk_check_and_clear(conn,
                                                    LOGIN_FLAGS_WRITE_ACTIVE))
                        goto err;

                /*
                 * Set the login timer thread pointer to NULL to prevent the
                 * login process from getting stuck if the initiator
                 * stops sending data.
                 */
                rc = iscsit_set_login_timer_kworker(conn, NULL);
                if (rc < 0)
                        goto err;
        } else if (rc == 1) {
                iscsit_stop_login_timer(conn);
                cancel_delayed_work(&conn->login_work);
                iscsi_target_nego_release(conn);
                iscsi_post_login_handler(np, conn, zero_tsih);
                iscsit_deaccess_np(np, tpg, tpg_np);
        }
        return;

err:
        iscsi_target_restore_sock_callbacks(conn);
        iscsit_stop_login_timer(conn);
        cancel_delayed_work(&conn->login_work);
        iscsi_target_login_drop(conn, login);
        iscsit_deaccess_np(np, tpg, tpg_np);
}

static void iscsi_target_sk_state_change(struct sock *sk)
{
        struct iscsit_conn *conn;
        void (*orig_state_change)(struct sock *);
        bool state;

        pr_debug("Entering iscsi_target_sk_state_change\n");

        write_lock_bh(&sk->sk_callback_lock);
        conn = sk->sk_user_data;
        if (!conn) {
                write_unlock_bh(&sk->sk_callback_lock);
                return;
        }
        orig_state_change = conn->orig_state_change;

        if (!test_bit(LOGIN_FLAGS_READY, &conn->login_flags)) {
                pr_debug("Got LOGIN_FLAGS_READY=0 sk_state_change conn: %p\n",
                         conn);
                write_unlock_bh(&sk->sk_callback_lock);
                orig_state_change(sk);
                return;
        }
        state = __iscsi_target_sk_check_close(sk);
        pr_debug("__iscsi_target_sk_close_change: state: %d\n", state);

        if (test_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags) ||
            test_bit(LOGIN_FLAGS_WRITE_ACTIVE, &conn->login_flags)) {
                pr_debug("Got LOGIN_FLAGS_{READ|WRITE}_ACTIVE=1"
                         " sk_state_change conn: %p\n", conn);
                if (state)
                        set_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags);
                write_unlock_bh(&sk->sk_callback_lock);
                orig_state_change(sk);
                return;
        }
        if (test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags)) {
                pr_debug("Got LOGIN_FLAGS_CLOSED=1 sk_state_change conn: %p\n",
                         conn);
                write_unlock_bh(&sk->sk_callback_lock);
                orig_state_change(sk);
                return;
        }
        /*
         * If the TCP connection has dropped, go ahead and set LOGIN_FLAGS_CLOSED,
         * but only queue conn->login_work -> iscsi_target_do_login_rx()
         * processing if LOGIN_FLAGS_INITIAL_PDU has already been cleared.
         *
         * When iscsi_target_do_login_rx() runs, iscsi_target_sk_check_close()
         * will detect the dropped TCP connection from delayed workqueue context.
         *
         * If LOGIN_FLAGS_INITIAL_PDU is still set, which means the initial
         * iscsi_target_start_negotiation() is running, iscsi_target_do_login()
         * via iscsi_target_sk_check_close() or iscsi_target_start_negotiation()
         * via iscsi_target_sk_check_and_clear() is responsible for detecting the
         * dropped TCP connection in iscsi_np process context, and cleaning up
         * the remaining iscsi connection resources.
         */
        if (state) {
                pr_debug("iscsi_target_sk_state_change got failed state\n");
                set_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags);
                state = test_bit(LOGIN_FLAGS_INITIAL_PDU, &conn->login_flags);
                write_unlock_bh(&sk->sk_callback_lock);

                orig_state_change(sk);

                if (!state)
                        schedule_delayed_work(&conn->login_work, 0);
                return;
        }
        write_unlock_bh(&sk->sk_callback_lock);

        orig_state_change(sk);
}

/*
 *      NOTE: We check for existing sessions or connections AFTER the initiator
 *      has been successfully authenticated in order to protect against faked
 *      ISID/TSIH combinations.
 */
static int iscsi_target_check_for_existing_instances(
        struct iscsit_conn *conn,
        struct iscsi_login *login)
{
        if (login->checked_for_existing)
                return 0;

        login->checked_for_existing = 1;

        if (!login->tsih)
                return iscsi_check_for_session_reinstatement(conn);
        else
                return iscsi_login_post_auth_non_zero_tsih(conn, login->cid,
                                login->initial_exp_statsn);
}

static int iscsi_target_do_authentication(
        struct iscsit_conn *conn,
        struct iscsi_login *login)
{
        int authret;
        u32 payload_length;
        struct iscsi_param *param;
        struct iscsi_login_req *login_req;
        struct iscsi_login_rsp *login_rsp;

        login_req = (struct iscsi_login_req *) login->req;
        login_rsp = (struct iscsi_login_rsp *) login->rsp;
        payload_length = ntoh24(login_req->dlength);

        param = iscsi_find_param_from_key(AUTHMETHOD, conn->param_list);
        if (!param)
                return -1;

        authret = iscsi_handle_authentication(
                        conn,
                        login->req_buf,
                        login->rsp_buf,
                        payload_length,
                        &login->rsp_length,
                        param->value);
        switch (authret) {
        case 0:
                pr_debug("Received OK response"
                " from LIO Authentication, continuing.\n");
                break;
        case 1:
                pr_debug("iSCSI security negotiation"
                        " completed successfully.\n");
                login->auth_complete = 1;
                if ((login_req->flags & ISCSI_FLAG_LOGIN_NEXT_STAGE1) &&
                    (login_req->flags & ISCSI_FLAG_LOGIN_TRANSIT)) {
                        login_rsp->flags |= (ISCSI_FLAG_LOGIN_NEXT_STAGE1 |
                                             ISCSI_FLAG_LOGIN_TRANSIT);
                        login->current_stage = 1;
                }
                return iscsi_target_check_for_existing_instances(
                                conn, login);
        case 2:
                pr_err("Security negotiation"
                        " failed.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_AUTH_FAILED);
                return -1;
        default:
                pr_err("Received unknown error %d from LIO"
                                " Authentication\n", authret);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                ISCSI_LOGIN_STATUS_TARGET_ERROR);
                return -1;
        }

        return 0;
}

bool iscsi_conn_auth_required(struct iscsit_conn *conn)
{
        struct iscsi_node_acl *nacl;
        struct se_node_acl *se_nacl;

        if (conn->sess->sess_ops->SessionType) {
                /*
                 * For SessionType=Discovery
                 */
                return conn->tpg->tpg_attrib.authentication;
        }
        /*
         * For SessionType=Normal
         */
        se_nacl = conn->sess->se_sess->se_node_acl;
        if (!se_nacl) {
                pr_debug("Unknown ACL is trying to connect\n");
                return true;
        }

        if (se_nacl->dynamic_node_acl) {
                pr_debug("Dynamic ACL %s is trying to connect\n",
                         se_nacl->initiatorname);
                return conn->tpg->tpg_attrib.authentication;
        }

        pr_debug("Known ACL %s is trying to connect\n",
                 se_nacl->initiatorname);

        nacl = to_iscsi_nacl(se_nacl);
        if (nacl->node_attrib.authentication == NA_AUTHENTICATION_INHERITED)
                return conn->tpg->tpg_attrib.authentication;

        return nacl->node_attrib.authentication;
}

static int iscsi_target_handle_csg_zero(
        struct iscsit_conn *conn,
        struct iscsi_login *login)
{
        int ret;
        u32 payload_length;
        struct iscsi_param *param;
        struct iscsi_login_req *login_req;
        struct iscsi_login_rsp *login_rsp;

        login_req = (struct iscsi_login_req *) login->req;
        login_rsp = (struct iscsi_login_rsp *) login->rsp;
        payload_length = ntoh24(login_req->dlength);

        param = iscsi_find_param_from_key(AUTHMETHOD, conn->param_list);
        if (!param)
                return -1;

        ret = iscsi_decode_text_input(
                        PHASE_SECURITY|PHASE_DECLARATIVE,
                        SENDER_INITIATOR|SENDER_RECEIVER,
                        login->req_buf,
                        payload_length,
                        conn);
        if (ret < 0)
                return -1;

        if (ret > 0) {
                if (login->auth_complete) {
                        pr_err("Initiator has already been"
                                " successfully authenticated, but is still"
                                " sending %s keys.\n", param->value);
                        iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                        ISCSI_LOGIN_STATUS_INIT_ERR);
                        return -1;
                }

                goto do_auth;
        } else if (!payload_length) {
                pr_err("Initiator sent zero length security payload,"
                       " login failed\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                    ISCSI_LOGIN_STATUS_AUTH_FAILED);
                return -1;
        }

        if (login->first_request)
                if (iscsi_target_check_first_request(conn, login) < 0)
                        return -1;

        ret = iscsi_encode_text_output(
                        PHASE_SECURITY|PHASE_DECLARATIVE,
                        SENDER_TARGET,
                        login->rsp_buf,
                        &login->rsp_length,
                        conn->param_list,
                        conn->tpg->tpg_attrib.login_keys_workaround);
        if (ret < 0)
                return -1;

        if (!iscsi_check_negotiated_keys(conn->param_list)) {
                bool auth_required = iscsi_conn_auth_required(conn);

                if (auth_required) {
                        if (!strncmp(param->value, NONE, 4)) {
                                pr_err("Initiator sent AuthMethod=None but"
                                       " Target is enforcing iSCSI Authentication,"
                                       " login failed.\n");
                                iscsit_tx_login_rsp(conn,
                                                ISCSI_STATUS_CLS_INITIATOR_ERR,
                                                ISCSI_LOGIN_STATUS_AUTH_FAILED);
                                return -1;
                        }

                        if (!login->auth_complete)
                                return 0;

                        if (strncmp(param->value, NONE, 4) &&
                            !login->auth_complete)
                                return 0;
                }

                if ((login_req->flags & ISCSI_FLAG_LOGIN_NEXT_STAGE1) &&
                    (login_req->flags & ISCSI_FLAG_LOGIN_TRANSIT)) {
                        login_rsp->flags |= ISCSI_FLAG_LOGIN_NEXT_STAGE1 |
                                            ISCSI_FLAG_LOGIN_TRANSIT;
                        login->current_stage = 1;
                }
        }

        return 0;
do_auth:
        return iscsi_target_do_authentication(conn, login);
}

static bool iscsi_conn_authenticated(struct iscsit_conn *conn,
                                     struct iscsi_login *login)
{
        if (!iscsi_conn_auth_required(conn))
                return true;

        if (login->auth_complete)
                return true;

        return false;
}

static int iscsi_target_handle_csg_one(struct iscsit_conn *conn, struct iscsi_login *login)
{
        int ret;
        u32 payload_length;
        struct iscsi_login_req *login_req;
        struct iscsi_login_rsp *login_rsp;

        login_req = (struct iscsi_login_req *) login->req;
        login_rsp = (struct iscsi_login_rsp *) login->rsp;
        payload_length = ntoh24(login_req->dlength);

        ret = iscsi_decode_text_input(
                        PHASE_OPERATIONAL|PHASE_DECLARATIVE,
                        SENDER_INITIATOR|SENDER_RECEIVER,
                        login->req_buf,
                        payload_length,
                        conn);
        if (ret < 0) {
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if (login->first_request)
                if (iscsi_target_check_first_request(conn, login) < 0)
                        return -1;

        if (iscsi_target_check_for_existing_instances(conn, login) < 0)
                return -1;

        ret = iscsi_encode_text_output(
                        PHASE_OPERATIONAL|PHASE_DECLARATIVE,
                        SENDER_TARGET,
                        login->rsp_buf,
                        &login->rsp_length,
                        conn->param_list,
                        conn->tpg->tpg_attrib.login_keys_workaround);
        if (ret < 0) {
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_INIT_ERR);
                return -1;
        }

        if (!iscsi_conn_authenticated(conn, login)) {
                pr_err("Initiator is requesting CSG: 1, has not been"
                       " successfully authenticated, and the Target is"
                       " enforcing iSCSI Authentication, login failed.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_AUTH_FAILED);
                return -1;
        }

        if (!iscsi_check_negotiated_keys(conn->param_list))
                if ((login_req->flags & ISCSI_FLAG_LOGIN_NEXT_STAGE3) &&
                    (login_req->flags & ISCSI_FLAG_LOGIN_TRANSIT))
                        login_rsp->flags |= ISCSI_FLAG_LOGIN_NEXT_STAGE3 |
                                            ISCSI_FLAG_LOGIN_TRANSIT;

        return 0;
}

/*
 * RETURN VALUE:
 *
 *  1 = Login successful
 * -1 = Login failed
 *  0 = More PDU exchanges required
 */
static int iscsi_target_do_login(struct iscsit_conn *conn, struct iscsi_login *login)
{
        int pdu_count = 0;
        struct iscsi_login_req *login_req;
        struct iscsi_login_rsp *login_rsp;

        login_req = (struct iscsi_login_req *) login->req;
        login_rsp = (struct iscsi_login_rsp *) login->rsp;

        while (1) {
                if (++pdu_count > MAX_LOGIN_PDUS) {
                        pr_err("MAX_LOGIN_PDUS count reached.\n");
                        iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                        ISCSI_LOGIN_STATUS_TARGET_ERROR);
                        return -1;
                }

                switch (ISCSI_LOGIN_CURRENT_STAGE(login_req->flags)) {
                case 0:
                        login_rsp->flags &= ~ISCSI_FLAG_LOGIN_CURRENT_STAGE_MASK;
                        if (iscsi_target_handle_csg_zero(conn, login) < 0)
                                return -1;
                        break;
                case 1:
                        login_rsp->flags |= ISCSI_FLAG_LOGIN_CURRENT_STAGE1;
                        if (iscsi_target_handle_csg_one(conn, login) < 0)
                                return -1;
                        if (login_rsp->flags & ISCSI_FLAG_LOGIN_TRANSIT) {
                                /*
                                 * Check to make sure the TCP connection has not
                                 * dropped asynchronously while session reinstatement
                                 * was occurring in this kthread context, before
                                 * transitioning to full feature phase operation.
                                 */
                                if (iscsi_target_sk_check_close(conn))
                                        return -1;

                                login->tsih = conn->sess->tsih;
                                login->login_complete = 1;
                                iscsi_target_restore_sock_callbacks(conn);
                                if (iscsi_target_do_tx_login_io(conn,
                                                login) < 0)
                                        return -1;
                                return 1;
                        }
                        break;
                default:
                        pr_err("Illegal CSG: %d received from"
                                " Initiator, protocol error.\n",
                                ISCSI_LOGIN_CURRENT_STAGE(login_req->flags));
                        break;
                }

                if (iscsi_target_do_tx_login_io(conn, login) < 0)
                        return -1;

                if (login_rsp->flags & ISCSI_FLAG_LOGIN_TRANSIT) {
                        login_rsp->flags &= ~ISCSI_FLAG_LOGIN_TRANSIT;
                        login_rsp->flags &= ~ISCSI_FLAG_LOGIN_NEXT_STAGE_MASK;
                }
                break;
        }

        return 0;
}

static void iscsi_initiatorname_tolower(
        char *param_buf)
{
        char *c;
        u32 iqn_size = strlen(param_buf), i;

        for (i = 0; i < iqn_size; i++) {
                c = &param_buf[i];
                if (!isupper(*c))
                        continue;

                *c = tolower(*c);
        }
}

/*
 * Processes the first Login Request..
 */
int iscsi_target_locate_portal(
        struct iscsi_np *np,
        struct iscsit_conn *conn,
        struct iscsi_login *login)
{
        char *i_buf = NULL, *s_buf = NULL, *t_buf = NULL;
        char *tmpbuf, *start = NULL, *end = NULL, *key, *value;
        struct iscsit_session *sess = conn->sess;
        struct iscsi_tiqn *tiqn;
        struct iscsi_tpg_np *tpg_np = NULL;
        struct iscsi_login_req *login_req;
        struct se_node_acl *se_nacl;
        u32 payload_length, queue_depth = 0;
        int sessiontype = 0, ret = 0, tag_num, tag_size;

        INIT_DELAYED_WORK(&conn->login_work, iscsi_target_do_login_rx);
        iscsi_target_set_sock_callbacks(conn);

        login->np = np;
        conn->tpg = NULL;

        login_req = (struct iscsi_login_req *) login->req;
        payload_length = ntoh24(login_req->dlength);

        tmpbuf = kmemdup_nul(login->req_buf, payload_length, GFP_KERNEL);
        if (!tmpbuf) {
                pr_err("Unable to allocate memory for tmpbuf.\n");
                return -1;
        }

        start = tmpbuf;
        end = (start + payload_length);

        /*
         * Locate the initial keys expected from the Initiator node in
         * the first login request in order to progress with the login phase.
         */
        while (start < end) {
                if (iscsi_extract_key_value(start, &key, &value) < 0) {
                        ret = -1;
                        goto out;
                }

                if (!strncmp(key, "InitiatorName", 13))
                        i_buf = value;
                else if (!strncmp(key, "SessionType", 11))
                        s_buf = value;
                else if (!strncmp(key, "TargetName", 10))
                        t_buf = value;

                start += strlen(key) + strlen(value) + 2;
        }
        /*
         * See 5.3.  Login Phase.
         */
        if (!i_buf) {
                pr_err("InitiatorName key not received"
                        " in first login request.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                        ISCSI_LOGIN_STATUS_MISSING_FIELDS);
                ret = -1;
                goto out;
        }
        /*
         * Convert the incoming InitiatorName to lowercase following
         * RFC-3720 3.2.6.1. section c) that says that iSCSI IQNs
         * are NOT case sensitive.
         */
        iscsi_initiatorname_tolower(i_buf);

        if (!s_buf) {
                if (!login->leading_connection)
                        goto get_target;

                pr_err("SessionType key not received"
                        " in first login request.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                        ISCSI_LOGIN_STATUS_MISSING_FIELDS);
                ret = -1;
                goto out;
        }

        /*
         * Use default portal group for discovery sessions.
         */
        sessiontype = strncmp(s_buf, DISCOVERY, 9);
        if (!sessiontype) {
                if (!login->leading_connection)
                        goto get_target;

                sess->sess_ops->SessionType = 1;

                /*
                 * Serialize access across the discovery struct iscsi_portal_group to
                 * process login attempt.
                 */
                conn->tpg = iscsit_global->discovery_tpg;
                if (iscsit_access_np(np, conn->tpg) < 0) {
                        iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                ISCSI_LOGIN_STATUS_SVC_UNAVAILABLE);
                        conn->tpg = NULL;
                        ret = -1;
                        goto out;
                }
                ret = 0;
                goto alloc_tags;
        }

get_target:
        if (!t_buf) {
                pr_err("TargetName key not received"
                        " in first login request while"
                        " SessionType=Normal.\n");
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                        ISCSI_LOGIN_STATUS_MISSING_FIELDS);
                ret = -1;
                goto out;
        }

        /*
         * Locate Target IQN from Storage Node.
         */
        tiqn = iscsit_get_tiqn_for_login(t_buf);
        if (!tiqn) {
                pr_err("Unable to locate Target IQN: %s in"
                        " Storage Node\n", t_buf);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                ISCSI_LOGIN_STATUS_SVC_UNAVAILABLE);
                ret = -1;
                goto out;
        }
        pr_debug("Located Storage Object: %s\n", tiqn->tiqn);

        /*
         * Locate Target Portal Group from Storage Node.
         */
        conn->tpg = iscsit_get_tpg_from_np(tiqn, np, &tpg_np);
        if (!conn->tpg) {
                pr_err("Unable to locate Target Portal Group"
                                " on %s\n", tiqn->tiqn);
                iscsit_put_tiqn_for_login(tiqn);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                ISCSI_LOGIN_STATUS_SVC_UNAVAILABLE);
                ret = -1;
                goto out;
        }
        conn->tpg_np = tpg_np;
        pr_debug("Located Portal Group Object: %hu\n", conn->tpg->tpgt);

        /*
         * Serialize access across the struct iscsi_portal_group to
         * process login attempt.
         */
        if (iscsit_access_np(np, conn->tpg) < 0) {
                kref_put(&tpg_np->tpg_np_kref, iscsit_login_kref_put);
                iscsit_put_tiqn_for_login(tiqn);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                ISCSI_LOGIN_STATUS_SVC_UNAVAILABLE);
                conn->tpg = NULL;
                ret = -1;
                goto out;
        }

        /*
         * conn->sess->node_acl will be set when the referenced
         * struct iscsit_session is located from received ISID+TSIH in
         * iscsi_login_non_zero_tsih_s2().
         */
        if (!login->leading_connection) {
                ret = 0;
                goto out;
        }

        /*
         * This value is required in iscsi_login_zero_tsih_s2()
         */
        sess->sess_ops->SessionType = 0;

        /*
         * Locate incoming Initiator IQN reference from Storage Node.
         */
        sess->se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
                        &conn->tpg->tpg_se_tpg, i_buf);
        if (!sess->se_sess->se_node_acl) {
                pr_err("iSCSI Initiator Node: %s is not authorized to"
                        " access iSCSI target portal group: %hu.\n",
                                i_buf, conn->tpg->tpgt);
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
                                ISCSI_LOGIN_STATUS_TGT_FORBIDDEN);
                ret = -1;
                goto out;
        }
        se_nacl = sess->se_sess->se_node_acl;
        queue_depth = se_nacl->queue_depth;
        /*
         * Setup pre-allocated tags based upon allowed per NodeACL CmdSN
         * depth for non immediate commands, plus extra tags for immediate
         * commands.
         *
         * Also enforce a ISCSIT_MIN_TAGS to prevent unnecessary contention
         * in per-cpu-ida tag allocation logic + small queue_depth.
         */
alloc_tags:
        tag_num = max_t(u32, ISCSIT_MIN_TAGS, queue_depth);
        tag_num = (tag_num * 2) + ISCSIT_EXTRA_TAGS;
        tag_size = sizeof(struct iscsit_cmd) + conn->conn_transport->priv_size;

        ret = transport_alloc_session_tags(sess->se_sess, tag_num, tag_size);
        if (ret < 0) {
                iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                    ISCSI_LOGIN_STATUS_NO_RESOURCES);
                ret = -1;
        }
out:
        kfree(tmpbuf);
        return ret;
}

int iscsi_target_start_negotiation(
        struct iscsi_login *login,
        struct iscsit_conn *conn)
{
        int ret;

        if (conn->sock) {
                struct sock *sk = conn->sock->sk;

                write_lock_bh(&sk->sk_callback_lock);
                set_bit(LOGIN_FLAGS_READY, &conn->login_flags);
                set_bit(LOGIN_FLAGS_INITIAL_PDU, &conn->login_flags);
                write_unlock_bh(&sk->sk_callback_lock);
        }
        /*
         * If iscsi_target_do_login returns zero to signal more PDU
         * exchanges are required to complete the login, go ahead and
         * clear LOGIN_FLAGS_INITIAL_PDU but only if the TCP connection
         * is still active.
         *
         * Otherwise if TCP connection dropped asynchronously, go ahead
         * and perform connection cleanup now.
         */
        ret = iscsi_target_do_login(conn, login);
        if (!ret) {
                spin_lock(&conn->login_worker_lock);

                if (iscsi_target_sk_check_and_clear(conn, LOGIN_FLAGS_INITIAL_PDU))
                        ret = -1;
                else if (!test_bit(LOGIN_FLAGS_WORKER_RUNNING, &conn->login_flags)) {
                        if (iscsit_set_login_timer_kworker(conn, NULL) < 0) {
                                /*
                                 * The timeout has expired already.
                                 * Schedule login_work to perform the cleanup.
                                 */
                                schedule_delayed_work(&conn->login_work, 0);
                        }
                }

                spin_unlock(&conn->login_worker_lock);
        }

        if (ret < 0) {
                iscsi_target_restore_sock_callbacks(conn);
                iscsi_remove_failed_auth_entry(conn);
        }
        if (ret != 0) {
                iscsit_stop_login_timer(conn);
                cancel_delayed_work_sync(&conn->login_work);
                iscsi_target_nego_release(conn);
        }

        return ret;
}

void iscsi_target_nego_release(struct iscsit_conn *conn)
{
        struct iscsi_login *login = conn->conn_login;

        if (!login)
                return;

        kfree(login->req_buf);
        kfree(login->rsp_buf);
        kfree(login);

        conn->conn_login = NULL;
}