// SPDX-License-Identifier: GPL-2.0
/*
 * Witness Service client for CIFS
 *
 * Copyright (c) 2020 Samuel Cabrero <scabrero@suse.de>
 */

#include <linux/kref.h>
#include <net/genetlink.h>
#include <uapi/linux/cifs/cifs_netlink.h>

#include "cifs_swn.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "fscache.h"
#include "cifs_debug.h"
#include "netlink.h"

static DEFINE_IDR(cifs_swnreg_idr);
static DEFINE_MUTEX(cifs_swnreg_idr_mutex);

struct cifs_swn_reg {
        int id;
        struct kref ref_count;

        const char *net_name;
        const char *share_name;
        bool net_name_notify;
        bool share_name_notify;
        bool ip_notify;

        struct cifs_tcon *tcon;
};

static int cifs_swn_auth_info_krb(struct cifs_tcon *tcon, struct sk_buff *skb)
{
        int ret;

        ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_KRB_AUTH);
        if (ret < 0)
                return ret;

        return 0;
}

static int cifs_swn_auth_info_ntlm(struct cifs_tcon *tcon, struct sk_buff *skb)
{
        int ret;

        if (tcon->ses->user_name != NULL) {
                ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_USER_NAME, tcon->ses->user_name);
                if (ret < 0)
                        return ret;
        }

        if (tcon->ses->password != NULL) {
                ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_PASSWORD, tcon->ses->password);
                if (ret < 0)
                        return ret;
        }

        if (tcon->ses->domainName != NULL) {
                ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_DOMAIN_NAME, tcon->ses->domainName);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

/*
 * Sends a register message to the userspace daemon based on the registration.
 * The authentication information to connect to the witness service is bundled
 * into the message.
 */
static int cifs_swn_send_register_message(struct cifs_swn_reg *swnreg)
{
        struct sk_buff *skb;
        struct genlmsghdr *hdr;
        enum securityEnum authtype;
        struct sockaddr_storage *addr;
        int ret;

        skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb)
                return -ENOMEM;

        hdr = genlmsg_put(skb, 0, 0, &cifs_genl_family, 0, CIFS_GENL_CMD_SWN_REGISTER);
        if (hdr == NULL) {
                ret = -ENOMEM;
                goto nlmsg_fail;
        }

        ret = nla_put_u32(skb, CIFS_GENL_ATTR_SWN_REGISTRATION_ID, swnreg->id);
        if (ret < 0)
                goto nlmsg_fail;

        ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_NET_NAME, swnreg->net_name);
        if (ret < 0)
                goto nlmsg_fail;

        ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME, swnreg->share_name);
        if (ret < 0)
                goto nlmsg_fail;

        /*
         * If there is an address stored use it instead of the server address, because we are
         * in the process of reconnecting to it after a share has been moved or we have been
         * told to switch to it (client move message). In these cases we unregister from the
         * server address and register to the new address when we receive the notification.
         */
        if (swnreg->tcon->ses->server->use_swn_dstaddr)
                addr = &swnreg->tcon->ses->server->swn_dstaddr;
        else
                addr = &swnreg->tcon->ses->server->dstaddr;

        ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage), addr);
        if (ret < 0)
                goto nlmsg_fail;

        if (swnreg->net_name_notify) {
                ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_NET_NAME_NOTIFY);
                if (ret < 0)
                        goto nlmsg_fail;
        }

        if (swnreg->share_name_notify) {
                ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME_NOTIFY);
                if (ret < 0)
                        goto nlmsg_fail;
        }

        if (swnreg->ip_notify) {
                ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_IP_NOTIFY);
                if (ret < 0)
                        goto nlmsg_fail;
        }

        authtype = cifs_select_sectype(swnreg->tcon->ses->server, swnreg->tcon->ses->sectype);
        switch (authtype) {
        case Kerberos:
                ret = cifs_swn_auth_info_krb(swnreg->tcon, skb);
                if (ret < 0) {
                        cifs_dbg(VFS, "%s: Failed to get kerberos auth info: %d\n", __func__, ret);
                        goto nlmsg_fail;
                }
                break;
        case NTLMv2:
        case RawNTLMSSP:
                ret = cifs_swn_auth_info_ntlm(swnreg->tcon, skb);
                if (ret < 0) {
                        cifs_dbg(VFS, "%s: Failed to get NTLM auth info: %d\n", __func__, ret);
                        goto nlmsg_fail;
                }
                break;
        default:
                cifs_dbg(VFS, "%s: secType %d not supported!\n", __func__, authtype);
                ret = -EINVAL;
                goto nlmsg_fail;
        }

        genlmsg_end(skb, hdr);
        genlmsg_multicast(&cifs_genl_family, skb, 0, CIFS_GENL_MCGRP_SWN, GFP_ATOMIC);

        cifs_dbg(FYI, "%s: Message to register for network name %s with id %d sent\n", __func__,
                        swnreg->net_name, swnreg->id);

        return 0;

nlmsg_fail:
        genlmsg_cancel(skb, hdr);
        nlmsg_free(skb);
        return ret;
}

/*
 * Sends an uregister message to the userspace daemon based on the registration
 */
static int cifs_swn_send_unregister_message(struct cifs_swn_reg *swnreg)
{
        struct sk_buff *skb;
        struct genlmsghdr *hdr;
        int ret;

        skb = genlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (skb == NULL)
                return -ENOMEM;

        hdr = genlmsg_put(skb, 0, 0, &cifs_genl_family, 0, CIFS_GENL_CMD_SWN_UNREGISTER);
        if (hdr == NULL) {
                ret = -ENOMEM;
                goto nlmsg_fail;
        }

        ret = nla_put_u32(skb, CIFS_GENL_ATTR_SWN_REGISTRATION_ID, swnreg->id);
        if (ret < 0)
                goto nlmsg_fail;

        ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_NET_NAME, swnreg->net_name);
        if (ret < 0)
                goto nlmsg_fail;

        ret = nla_put_string(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME, swnreg->share_name);
        if (ret < 0)
                goto nlmsg_fail;

        ret = nla_put(skb, CIFS_GENL_ATTR_SWN_IP, sizeof(struct sockaddr_storage),
                        &swnreg->tcon->ses->server->dstaddr);
        if (ret < 0)
                goto nlmsg_fail;

        if (swnreg->net_name_notify) {
                ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_NET_NAME_NOTIFY);
                if (ret < 0)
                        goto nlmsg_fail;
        }

        if (swnreg->share_name_notify) {
                ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_SHARE_NAME_NOTIFY);
                if (ret < 0)
                        goto nlmsg_fail;
        }

        if (swnreg->ip_notify) {
                ret = nla_put_flag(skb, CIFS_GENL_ATTR_SWN_IP_NOTIFY);
                if (ret < 0)
                        goto nlmsg_fail;
        }

        genlmsg_end(skb, hdr);
        genlmsg_multicast(&cifs_genl_family, skb, 0, CIFS_GENL_MCGRP_SWN, GFP_ATOMIC);

        cifs_dbg(FYI, "%s: Message to unregister for network name %s with id %d sent\n", __func__,
                        swnreg->net_name, swnreg->id);

        return 0;

nlmsg_fail:
        genlmsg_cancel(skb, hdr);
        nlmsg_free(skb);
        return ret;
}

/*
 * Try to find a matching registration for the tcon's server name and share name.
 * Calls to this function must be protected by cifs_swnreg_idr_mutex.
 * TODO Try to avoid memory allocations
 */
static struct cifs_swn_reg *cifs_find_swn_reg(struct cifs_tcon *tcon)
{
        struct cifs_swn_reg *swnreg;
        int id;
        const char *share_name;
        const char *net_name;

        net_name = extract_hostname(tcon->tree_name);
        if (IS_ERR(net_name)) {
                int ret;

                ret = PTR_ERR(net_name);
                cifs_dbg(VFS, "%s: failed to extract host name from target '%s': %d\n",
                                __func__, tcon->tree_name, ret);
                return ERR_PTR(-EINVAL);
        }

        share_name = extract_sharename(tcon->tree_name);
        if (IS_ERR(share_name)) {
                int ret;

                ret = PTR_ERR(share_name);
                cifs_dbg(VFS, "%s: failed to extract share name from target '%s': %d\n",
                                __func__, tcon->tree_name, ret);
                kfree(net_name);
                return ERR_PTR(-EINVAL);
        }

        idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
                if (strcasecmp(swnreg->net_name, net_name) != 0
                    || strcasecmp(swnreg->share_name, share_name) != 0) {
                        continue;
                }

                cifs_dbg(FYI, "Existing swn registration for %s:%s found\n", swnreg->net_name,
                                swnreg->share_name);

                kfree(net_name);
                kfree(share_name);

                return swnreg;
        }

        kfree(net_name);
        kfree(share_name);

        return ERR_PTR(-EEXIST);
}

/*
 * Get a registration for the tcon's server and share name, allocating a new one if it does not
 * exists
 */
static struct cifs_swn_reg *cifs_get_swn_reg(struct cifs_tcon *tcon)
{
        struct cifs_swn_reg *reg = NULL;
        int ret;

        mutex_lock(&cifs_swnreg_idr_mutex);

        /* Check if we are already registered for this network and share names */
        reg = cifs_find_swn_reg(tcon);
        if (!IS_ERR(reg)) {
                kref_get(&reg->ref_count);
                goto unlock;
        } else if (PTR_ERR(reg) != -EEXIST) {
                goto unlock;
        }

        reg = kmalloc_obj(struct cifs_swn_reg, GFP_ATOMIC);
        if (reg == NULL) {
                ret = -ENOMEM;
                goto fail_unlock;
        }

        kref_init(&reg->ref_count);

        reg->id = idr_alloc(&cifs_swnreg_idr, reg, 1, 0, GFP_ATOMIC);
        if (reg->id < 0) {
                cifs_dbg(FYI, "%s: failed to allocate registration id\n", __func__);
                ret = reg->id;
                goto fail;
        }

        reg->net_name = extract_hostname(tcon->tree_name);
        if (IS_ERR(reg->net_name)) {
                ret = PTR_ERR(reg->net_name);
                cifs_dbg(VFS, "%s: failed to extract host name from target: %d\n", __func__, ret);
                goto fail_idr;
        }

        reg->share_name = extract_sharename(tcon->tree_name);
        if (IS_ERR(reg->share_name)) {
                ret = PTR_ERR(reg->share_name);
                cifs_dbg(VFS, "%s: failed to extract share name from target: %d\n", __func__, ret);
                goto fail_net_name;
        }

        reg->net_name_notify = true;
        reg->share_name_notify = true;
        reg->ip_notify = (tcon->capabilities & SMB2_SHARE_CAP_SCALEOUT);

        reg->tcon = tcon;
unlock:
        mutex_unlock(&cifs_swnreg_idr_mutex);

        return reg;

fail_net_name:
        kfree(reg->net_name);
fail_idr:
        idr_remove(&cifs_swnreg_idr, reg->id);
fail:
        kfree(reg);
fail_unlock:
        mutex_unlock(&cifs_swnreg_idr_mutex);
        return ERR_PTR(ret);
}

static void cifs_swn_reg_release(struct kref *ref)
{
        struct cifs_swn_reg *swnreg = container_of(ref, struct cifs_swn_reg, ref_count);
        int ret;

        ret = cifs_swn_send_unregister_message(swnreg);
        if (ret < 0)
                cifs_dbg(VFS, "%s: Failed to send unregister message: %d\n", __func__, ret);

        idr_remove(&cifs_swnreg_idr, swnreg->id);
        kfree(swnreg->net_name);
        kfree(swnreg->share_name);
        kfree(swnreg);
}

static void cifs_put_swn_reg(struct cifs_swn_reg *swnreg)
{
        mutex_lock(&cifs_swnreg_idr_mutex);
        kref_put(&swnreg->ref_count, cifs_swn_reg_release);
        mutex_unlock(&cifs_swnreg_idr_mutex);
}

static int cifs_swn_resource_state_changed(struct cifs_swn_reg *swnreg, const char *name, int state)
{
        switch (state) {
        case CIFS_SWN_RESOURCE_STATE_UNAVAILABLE:
                cifs_dbg(FYI, "%s: resource name '%s' become unavailable\n", __func__, name);
                cifs_signal_cifsd_for_reconnect(swnreg->tcon->ses->server, true);
                break;
        case CIFS_SWN_RESOURCE_STATE_AVAILABLE:
                cifs_dbg(FYI, "%s: resource name '%s' become available\n", __func__, name);
                cifs_signal_cifsd_for_reconnect(swnreg->tcon->ses->server, true);
                break;
        case CIFS_SWN_RESOURCE_STATE_UNKNOWN:
                cifs_dbg(FYI, "%s: resource name '%s' changed to unknown state\n", __func__, name);
                break;
        }
        return 0;
}

static bool cifs_sockaddr_equal(struct sockaddr_storage *addr1, struct sockaddr_storage *addr2)
{
        if (addr1->ss_family != addr2->ss_family)
                return false;

        if (addr1->ss_family == AF_INET) {
                return (memcmp(&((const struct sockaddr_in *)addr1)->sin_addr,
                                &((const struct sockaddr_in *)addr2)->sin_addr,
                                sizeof(struct in_addr)) == 0);
        }

        if (addr1->ss_family == AF_INET6) {
                return (memcmp(&((const struct sockaddr_in6 *)addr1)->sin6_addr,
                                &((const struct sockaddr_in6 *)addr2)->sin6_addr,
                                sizeof(struct in6_addr)) == 0);
        }

        return false;
}

static int cifs_swn_store_swn_addr(const struct sockaddr_storage *new,
                                   const struct sockaddr_storage *old,
                                   struct sockaddr_storage *dst)
{
        __be16 port = cpu_to_be16(CIFS_PORT);

        if (old->ss_family == AF_INET) {
                struct sockaddr_in *ipv4 = (struct sockaddr_in *)old;

                port = ipv4->sin_port;
        } else if (old->ss_family == AF_INET6) {
                struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)old;

                port = ipv6->sin6_port;
        }

        if (new->ss_family == AF_INET) {
                struct sockaddr_in *ipv4 = (struct sockaddr_in *)new;

                ipv4->sin_port = port;
        } else if (new->ss_family == AF_INET6) {
                struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)new;

                ipv6->sin6_port = port;
        }

        *dst = *new;

        return 0;
}

static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *addr)
{
        int ret = 0;

        /* Store the reconnect address */
        cifs_server_lock(tcon->ses->server);
        if (cifs_sockaddr_equal(&tcon->ses->server->dstaddr, addr))
                goto unlock;

        ret = cifs_swn_store_swn_addr(addr, &tcon->ses->server->dstaddr,
                                      &tcon->ses->server->swn_dstaddr);
        if (ret < 0) {
                cifs_dbg(VFS, "%s: failed to store address: %d\n", __func__, ret);
                goto unlock;
        }
        tcon->ses->server->use_swn_dstaddr = true;

        /*
         * Unregister to stop receiving notifications for the old IP address.
         */
        ret = cifs_swn_unregister(tcon);
        if (ret < 0) {
                cifs_dbg(VFS, "%s: Failed to unregister for witness notifications: %d\n",
                         __func__, ret);
                goto unlock;
        }

        /*
         * And register to receive notifications for the new IP address now that we have
         * stored the new address.
         */
        ret = cifs_swn_register(tcon);
        if (ret < 0) {
                cifs_dbg(VFS, "%s: Failed to register for witness notifications: %d\n",
                         __func__, ret);
                goto unlock;
        }

        cifs_signal_cifsd_for_reconnect(tcon->ses->server, false);

unlock:
        cifs_server_unlock(tcon->ses->server);

        return ret;
}

static int cifs_swn_client_move(struct cifs_swn_reg *swnreg, struct sockaddr_storage *addr)
{
        struct sockaddr_in *ipv4 = (struct sockaddr_in *)addr;
        struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)addr;

        if (addr->ss_family == AF_INET)
                cifs_dbg(FYI, "%s: move to %pI4\n", __func__, &ipv4->sin_addr);
        else if (addr->ss_family == AF_INET6)
                cifs_dbg(FYI, "%s: move to %pI6\n", __func__, &ipv6->sin6_addr);

        return cifs_swn_reconnect(swnreg->tcon, addr);
}

int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info)
{
        struct cifs_swn_reg *swnreg;
        char name[256];
        int type;

        if (info->attrs[CIFS_GENL_ATTR_SWN_REGISTRATION_ID]) {
                int swnreg_id;

                swnreg_id = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_REGISTRATION_ID]);
                mutex_lock(&cifs_swnreg_idr_mutex);
                swnreg = idr_find(&cifs_swnreg_idr, swnreg_id);
                mutex_unlock(&cifs_swnreg_idr_mutex);
                if (swnreg == NULL) {
                        cifs_dbg(FYI, "%s: registration id %d not found\n", __func__, swnreg_id);
                        return -EINVAL;
                }
        } else {
                cifs_dbg(FYI, "%s: missing registration id attribute\n", __func__);
                return -EINVAL;
        }

        if (info->attrs[CIFS_GENL_ATTR_SWN_NOTIFICATION_TYPE]) {
                type = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_NOTIFICATION_TYPE]);
        } else {
                cifs_dbg(FYI, "%s: missing notification type attribute\n", __func__);
                return -EINVAL;
        }

        switch (type) {
        case CIFS_SWN_NOTIFICATION_RESOURCE_CHANGE: {
                int state;

                if (info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_NAME]) {
                        nla_strscpy(name, info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_NAME],
                                        sizeof(name));
                } else {
                        cifs_dbg(FYI, "%s: missing resource name attribute\n", __func__);
                        return -EINVAL;
                }
                if (info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_STATE]) {
                        state = nla_get_u32(info->attrs[CIFS_GENL_ATTR_SWN_RESOURCE_STATE]);
                } else {
                        cifs_dbg(FYI, "%s: missing resource state attribute\n", __func__);
                        return -EINVAL;
                }
                return cifs_swn_resource_state_changed(swnreg, name, state);
        }
        case CIFS_SWN_NOTIFICATION_CLIENT_MOVE: {
                struct sockaddr_storage addr;

                if (info->attrs[CIFS_GENL_ATTR_SWN_IP]) {
                        nla_memcpy(&addr, info->attrs[CIFS_GENL_ATTR_SWN_IP], sizeof(addr));
                } else {
                        cifs_dbg(FYI, "%s: missing IP address attribute\n", __func__);
                        return -EINVAL;
                }
                return cifs_swn_client_move(swnreg, &addr);
        }
        default:
                cifs_dbg(FYI, "%s: unknown notification type %d\n", __func__, type);
                break;
        }

        return 0;
}

int cifs_swn_register(struct cifs_tcon *tcon)
{
        struct cifs_swn_reg *swnreg;
        int ret;

        swnreg = cifs_get_swn_reg(tcon);
        if (IS_ERR(swnreg))
                return PTR_ERR(swnreg);

        ret = cifs_swn_send_register_message(swnreg);
        if (ret < 0) {
                cifs_dbg(VFS, "%s: Failed to send swn register message: %d\n", __func__, ret);
                /* Do not put the swnreg or return error, the echo task will retry */
        }

        return 0;
}

int cifs_swn_unregister(struct cifs_tcon *tcon)
{
        struct cifs_swn_reg *swnreg;

        mutex_lock(&cifs_swnreg_idr_mutex);

        swnreg = cifs_find_swn_reg(tcon);
        if (IS_ERR(swnreg)) {
                mutex_unlock(&cifs_swnreg_idr_mutex);
                return PTR_ERR(swnreg);
        }

        mutex_unlock(&cifs_swnreg_idr_mutex);

        cifs_put_swn_reg(swnreg);

        return 0;
}

void cifs_swn_dump(struct seq_file *m)
{
        struct cifs_swn_reg *swnreg;
        struct sockaddr_in *sa;
        struct sockaddr_in6 *sa6;
        int id;

        seq_puts(m, "Witness registrations:");

        mutex_lock(&cifs_swnreg_idr_mutex);
        idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
                seq_printf(m, "\nId: %u Refs: %u Network name: '%s'%s Share name: '%s'%s Ip address: ",
                                id, kref_read(&swnreg->ref_count),
                                swnreg->net_name, swnreg->net_name_notify ? "(y)" : "(n)",
                                swnreg->share_name, swnreg->share_name_notify ? "(y)" : "(n)");
                switch (swnreg->tcon->ses->server->dstaddr.ss_family) {
                case AF_INET:
                        sa = (struct sockaddr_in *) &swnreg->tcon->ses->server->dstaddr;
                        seq_printf(m, "%pI4", &sa->sin_addr.s_addr);
                        break;
                case AF_INET6:
                        sa6 = (struct sockaddr_in6 *) &swnreg->tcon->ses->server->dstaddr;
                        seq_printf(m, "%pI6", &sa6->sin6_addr.s6_addr);
                        if (sa6->sin6_scope_id)
                                seq_printf(m, "%%%u", sa6->sin6_scope_id);
                        break;
                default:
                        seq_puts(m, "(unknown)");
                }
                seq_printf(m, "%s", swnreg->ip_notify ? "(y)" : "(n)");
        }
        mutex_unlock(&cifs_swnreg_idr_mutex);
        seq_puts(m, "\n");
}

void cifs_swn_check(void)
{
        struct cifs_swn_reg *swnreg;
        int id;
        int ret;

        mutex_lock(&cifs_swnreg_idr_mutex);
        idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
                ret = cifs_swn_send_register_message(swnreg);
                if (ret < 0)
                        cifs_dbg(FYI, "%s: Failed to send register message: %d\n", __func__, ret);
        }
        mutex_unlock(&cifs_swnreg_idr_mutex);
}