// 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_swn_reg_info {
        int id;
        unsigned int ref_count;
        const char *net_name;
        const char *share_name;
        bool net_name_notify;
        bool share_name_notify;
        bool ip_notify;
};

static void cifs_swn_snapshot_reg(struct cifs_swn_reg *swnreg,
                                  struct cifs_swn_reg_info *info)
{
        info->id = swnreg->id;
        info->ref_count = kref_read(&swnreg->ref_count);
        info->net_name = swnreg->net_name;
        info->share_name = swnreg->share_name;
        info->net_name_notify = swnreg->net_name_notify;
        info->share_name_notify = swnreg->share_name_notify;
        info->ip_notify = swnreg->ip_notify;
}

static int cifs_swn_dup_reg(struct cifs_swn_reg *swnreg,
                            struct cifs_swn_reg_info *info)
{
        cifs_swn_snapshot_reg(swnreg, info);

        info->net_name = kstrdup(swnreg->net_name, GFP_KERNEL);
        if (!info->net_name)
                return -ENOMEM;

        info->share_name = kstrdup(swnreg->share_name, GFP_KERNEL);
        if (!info->share_name) {
                kfree(info->net_name);
                return -ENOMEM;
        }

        return 0;
}

static void cifs_swn_free_reg_info(struct cifs_swn_reg_info *info)
{
        kfree(info->net_name);
        kfree(info->share_name);
}

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_info *swnreg,
                                          struct cifs_tcon *tcon)
{
        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 (tcon->ses->server->use_swn_dstaddr)
                addr = &tcon->ses->server->swn_dstaddr;
        else
                addr = &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(tcon->ses->server, tcon->ses->sectype);
        switch (authtype) {
        case Kerberos:
                ret = cifs_swn_auth_info_krb(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(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_info *swnreg,
                                            struct cifs_tcon *tcon)
{
        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),
                        &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;
}

/*
 * Allocation-free mirror of extract_hostname() + extract_sharename() from
 * fs/smb/client/unc.c.  Those helpers kmalloc(GFP_KERNEL); this runs under
 * cifs_tcp_ses_lock and tcon->tc_lock, both spinlocks, so we mirror their
 * parsing in place against the caller's stable net_name/share_name strings.
 * Keep in sync with unc.c.
 */
static bool cifs_swn_tcon_matches(struct cifs_tcon *tcon,
                                  const char *net_name,
                                  const char *share_name)
{
        const char *unc = tcon->tree_name;
        const char *host, *share, *delim;
        size_t host_len, share_len;

        if (!tcon->use_witness)
                return false;

        /* extract_hostname: require strlen(unc) >= 3 */
        if (strnlen(unc, 3) < 3)
                return false;
        /* extract_hostname: skip all leading '\' characters */
        for (host = unc; *host == '\\'; host++)
                ;
        if (!*host)
                return false;
        delim = strchr(host, '\\');
        if (!delim)
                return false;
        host_len = delim - host;
        if (strlen(net_name) != host_len ||
            strncasecmp(host, net_name, host_len))
                return false;

        /* extract_sharename: start at unc + 2, then first '\' onward */
        share = unc + 2;
        delim = strchr(share, '\\');
        if (!delim)
                return false;
        share = delim + 1;
        share_len = strlen(share);

        return strlen(share_name) == share_len &&
               !strncasecmp(share, share_name, share_len);
}

/*
 * One SWN registration id represents one net/share name pair.  Multiple
 * mounted tcons can therefore share the id.  Pick a live representative at
 * use time instead of caching the first tcon pointer in the registration.
 */
static struct cifs_tcon *cifs_swn_get_tcon(struct cifs_swn_reg_info *swnreg)
{
        struct TCP_Server_Info *server;
        struct cifs_ses *ses;
        struct cifs_tcon *tcon;

        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
                list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
                        list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
                                spin_lock(&tcon->tc_lock);
                                if (tcon->status == TID_EXITING ||
                                    !cifs_swn_tcon_matches(tcon, swnreg->net_name,
                                                           swnreg->share_name)) {
                                        spin_unlock(&tcon->tc_lock);
                                        continue;
                                }
                                ++tcon->tc_count;
                                trace_smb3_tcon_ref(tcon->debug_id,
                                                    tcon->tc_count,
                                                    netfs_trace_tcon_ref_get_swn_notify);
                                spin_unlock(&tcon->tc_lock);
                                spin_unlock(&cifs_tcp_ses_lock);
                                return tcon;
                        }
                }
        }
        spin_unlock(&cifs_tcp_ses_lock);
        return NULL;
}

/*
 * 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
 * exist.
 */
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_KERNEL);
        if (reg == NULL) {
                ret = -ENOMEM;
                goto fail_unlock;
        }

        kref_init(&reg->ref_count);

        reg->id = idr_alloc(&cifs_swnreg_idr, reg, 1, 0, GFP_KERNEL);
        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);
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);

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

static void cifs_put_swn_reg_locked(struct cifs_swn_reg *swnreg,
                                    struct cifs_tcon *tcon)
{
        if (kref_read(&swnreg->ref_count) == 1) {
                struct cifs_swn_reg_info swnreg_info;
                int ret;

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

        kref_put(&swnreg->ref_count, cifs_swn_reg_release);
}

static int cifs_swn_resource_state_changed(struct cifs_tcon *tcon, 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(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(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_tcon *tcon, 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(tcon, addr);
}

int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info)
{
        struct cifs_swn_reg *swnreg;
        struct cifs_swn_reg_info swnreg_info;
        struct cifs_tcon *tcon;
        char name[256];
        int type;
        int ret = 0;

        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);
                if (swnreg == NULL) {
                        mutex_unlock(&cifs_swnreg_idr_mutex);
                        cifs_dbg(FYI, "%s: registration id %d not found\n", __func__, swnreg_id);
                        return -EINVAL;
                }
                ret = cifs_swn_dup_reg(swnreg, &swnreg_info);
                mutex_unlock(&cifs_swnreg_idr_mutex);
                if (ret)
                        return ret;
        } else {
                cifs_dbg(FYI, "%s: missing registration id attribute\n", __func__);
                return -EINVAL;
        }

        tcon = cifs_swn_get_tcon(&swnreg_info);
        if (!tcon) {
                cifs_dbg(FYI, "%s: registration id %d has no live tcon\n",
                         __func__, swnreg_info.id);
                ret = -ENODEV;
                goto free_info;
        }

        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__);
                ret = -EINVAL;
                goto out;
        }

        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__);
                        ret = -EINVAL;
                        goto out;
                }
                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__);
                        ret = -EINVAL;
                        goto out;
                }
                ret = cifs_swn_resource_state_changed(tcon, name, state);
                break;
        }
        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__);
                        ret = -EINVAL;
                        goto out;
                }
                ret = cifs_swn_client_move(tcon, &addr);
                break;
        }
        default:
                cifs_dbg(FYI, "%s: unknown notification type %d\n", __func__, type);
                break;
        }

out:
        cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_swn_notify);
free_info:
        cifs_swn_free_reg_info(&swnreg_info);
        return ret;
}

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

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

        cifs_swn_snapshot_reg(swnreg, &swnreg_info);
        ret = cifs_swn_send_register_message(&swnreg_info, tcon);
        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);
        }

        cifs_put_swn_reg_locked(swnreg, tcon);
        mutex_unlock(&cifs_swnreg_idr_mutex);

        return 0;
}

/*
 * Snapshot one registration under cifs_swnreg_idr_mutex and return.  Callers
 * intentionally do the per-registration network/genlmsg work without the
 * mutex held, both to keep the critical section short and to avoid nesting
 * cifs_swnreg_idr_mutex inside the higher tc_lock when a live tcon is then
 * pinned for the send.
 */
static int cifs_swn_get_next_reg_info(int *id, struct cifs_swn_reg_info *info)
{
        struct cifs_swn_reg *swnreg;
        int ret = 0;

        mutex_lock(&cifs_swnreg_idr_mutex);
        swnreg = idr_get_next(&cifs_swnreg_idr, id);
        if (swnreg) {
                ret = cifs_swn_dup_reg(swnreg, info);
                if (!ret) {
                        *id = swnreg->id + 1;
                        ret = 1;
                }
        }
        mutex_unlock(&cifs_swnreg_idr_mutex);

        return ret;
}

void cifs_swn_dump(struct seq_file *m)
{
        struct cifs_swn_reg_info swnreg_info;
        struct cifs_tcon *tcon;
        struct sockaddr_in *sa;
        struct sockaddr_in6 *sa6;
        int id = 0;
        int ret;

        seq_puts(m, "Witness registrations:");

        while ((ret = cifs_swn_get_next_reg_info(&id, &swnreg_info)) > 0) {
                seq_printf(m, "\nId: %u Refs: %u Network name: '%s'%s Share name: '%s'%s Ip address: ",
                           swnreg_info.id, swnreg_info.ref_count,
                           swnreg_info.net_name, swnreg_info.net_name_notify ? "(y)" : "(n)",
                           swnreg_info.share_name, swnreg_info.share_name_notify ? "(y)" : "(n)");

                tcon = cifs_swn_get_tcon(&swnreg_info);
                if (!tcon) {
                        seq_puts(m, "(no live tcon)");
                        goto next;
                }

                switch (tcon->ses->server->dstaddr.ss_family) {
                case AF_INET:
                        sa = (struct sockaddr_in *)&tcon->ses->server->dstaddr;
                        seq_printf(m, "%pI4", &sa->sin_addr.s_addr);
                        break;
                case AF_INET6:
                        sa6 = (struct sockaddr_in6 *)&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)");
                }
                cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_swn_notify);
next:
                seq_printf(m, "%s", swnreg_info.ip_notify ? "(y)" : "(n)");
                cifs_swn_free_reg_info(&swnreg_info);
        }
        if (ret < 0)
                seq_printf(m, "\nFailed to snapshot witness registration: %d", ret);
        seq_puts(m, "\n");
}

void cifs_swn_check(void)
{
        struct cifs_swn_reg_info swnreg_info;
        struct cifs_tcon *tcon;
        int id = 0;
        int ret;

        while ((ret = cifs_swn_get_next_reg_info(&id, &swnreg_info)) > 0) {
                tcon = cifs_swn_get_tcon(&swnreg_info);
                if (!tcon) {
                        cifs_dbg(FYI, "%s: registration id %d has no live tcon\n",
                                 __func__, swnreg_info.id);
                        goto free_info;
                }

                ret = cifs_swn_send_register_message(&swnreg_info, tcon);
                if (ret < 0)
                        cifs_dbg(FYI, "%s: Failed to send register message: %d\n", __func__, ret);
                cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_swn_notify);
free_info:
                cifs_swn_free_reg_info(&swnreg_info);
        }
        if (ret < 0)
                cifs_dbg(FYI, "%s: Failed to snapshot registration: %d\n", __func__, ret);
}