fs/cifs/cifs_swn.c - linux - Git at Google

 // 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 == NULL) {
 		ret = -ENOMEM;
 		goto fail;
 	}

 	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);
 fail:
 	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->treeName);
 	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->treeName, ret);
 		return ERR_PTR(-EINVAL);
 	}

 	share_name = extract_sharename(tcon->treeName);
 	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->treeName, 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);
 		mutex_unlock(&cifs_swnreg_idr_mutex);
 		return reg;
 	} else if (PTR_ERR(reg) != -EEXIST) {
 		mutex_unlock(&cifs_swnreg_idr_mutex);
 		return reg;
 	}

 	reg = kmalloc(sizeof(struct cifs_swn_reg), GFP_ATOMIC);
 	if (reg == NULL) {
 		mutex_unlock(&cifs_swnreg_idr_mutex);
 		return ERR_PTR(-ENOMEM);
 	}

 	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->treeName);
 	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->treeName);
 	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;

 	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);
 	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);
 }
	// 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 == NULL) {
	ret = -ENOMEM;
	goto fail;
	}

	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);
	fail:
	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->treeName);
	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->treeName, ret);
	return ERR_PTR(-EINVAL);
	}

	share_name = extract_sharename(tcon->treeName);
	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->treeName, 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);
	mutex_unlock(&cifs_swnreg_idr_mutex);
	return reg;
	} else if (PTR_ERR(reg) != -EEXIST) {
	mutex_unlock(&cifs_swnreg_idr_mutex);
	return reg;
	}

	reg = kmalloc(sizeof(struct cifs_swn_reg), GFP_ATOMIC);
	if (reg == NULL) {
	mutex_unlock(&cifs_swnreg_idr_mutex);
	return ERR_PTR(-ENOMEM);
	}

	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->treeName);
	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->treeName);
	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;

	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);
	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);
	}