fs/afs/vl_list.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* AFS vlserver list management.
  *
  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */

 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include "internal.h"

 struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
 					unsigned short port)
 {
 	struct afs_vlserver *vlserver;

 	vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
 			   GFP_KERNEL);
 	if (vlserver) {
 		refcount_set(&vlserver->ref, 1);
 		rwlock_init(&vlserver->lock);
 		init_waitqueue_head(&vlserver->probe_wq);
 		spin_lock_init(&vlserver->probe_lock);
 		vlserver->rtt = UINT_MAX;
 		vlserver->name_len = name_len;
 		vlserver->port = port;
 		memcpy(vlserver->name, name, name_len);
 	}
 	return vlserver;
 }

 static void afs_vlserver_rcu(struct rcu_head *rcu)
 {
 	struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);

 	afs_put_addrlist(rcu_access_pointer(vlserver->addresses));
 	kfree_rcu(vlserver, rcu);
 }

 void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
 {
 	if (vlserver &&
 	    refcount_dec_and_test(&vlserver->ref))
 		call_rcu(&vlserver->rcu, afs_vlserver_rcu);
 }

 struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
 {
 	struct afs_vlserver_list *vllist;

 	vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
 	if (vllist) {
 		refcount_set(&vllist->ref, 1);
 		rwlock_init(&vllist->lock);
 	}

 	return vllist;
 }

 void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
 {
 	if (vllist) {
 		if (refcount_dec_and_test(&vllist->ref)) {
 			int i;

 			for (i = 0; i < vllist->nr_servers; i++) {
 				afs_put_vlserver(net, vllist->servers[i].server);
 			}
 			kfree_rcu(vllist, rcu);
 		}
 	}
 }

 static u16 afs_extract_le16(const u8 **_b)
 {
 	u16 val;

 	val  = (u16)*(*_b)++ << 0;
 	val |= (u16)*(*_b)++ << 8;
 	return val;
 }

 /*
  * Build a VL server address list from a DNS queried server list.
  */
 static struct afs_addr_list *afs_extract_vl_addrs(const u8 **_b, const u8 *end,
 						  u8 nr_addrs, u16 port)
 {
 	struct afs_addr_list *alist;
 	const u8 *b = *_b;
 	int ret = -EINVAL;

 	alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE, port);
 	if (!alist)
 		return ERR_PTR(-ENOMEM);
 	if (nr_addrs == 0)
 		return alist;

 	for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
 		struct dns_server_list_v1_address hdr;
 		__be32 x[4];

 		hdr.address_type = *b++;

 		switch (hdr.address_type) {
 		case DNS_ADDRESS_IS_IPV4:
 			if (end - b < 4) {
 				_leave(" = -EINVAL [short inet]");
 				goto error;
 			}
 			memcpy(x, b, 4);
 			afs_merge_fs_addr4(alist, x[0], port);
 			b += 4;
 			break;

 		case DNS_ADDRESS_IS_IPV6:
 			if (end - b < 16) {
 				_leave(" = -EINVAL [short inet6]");
 				goto error;
 			}
 			memcpy(x, b, 16);
 			afs_merge_fs_addr6(alist, x, port);
 			b += 16;
 			break;

 		default:
 			_leave(" = -EADDRNOTAVAIL [unknown af %u]",
 			       hdr.address_type);
 			ret = -EADDRNOTAVAIL;
 			goto error;
 		}
 	}

 	/* Start with IPv6 if available. */
 	if (alist->nr_ipv4 < alist->nr_addrs)
 		alist->preferred = alist->nr_ipv4;

 	*_b = b;
 	return alist;

 error:
 	*_b = b;
 	afs_put_addrlist(alist);
 	return ERR_PTR(ret);
 }

 /*
  * Build a VL server list from a DNS queried server list.
  */
 struct afs_vlserver_list *afs_extract_vlserver_list(struct afs_cell *cell,
 						    const void *buffer,
 						    size_t buffer_size)
 {
 	const struct dns_server_list_v1_header *hdr = buffer;
 	struct dns_server_list_v1_server bs;
 	struct afs_vlserver_list *vllist, *previous;
 	struct afs_addr_list *addrs;
 	struct afs_vlserver *server;
 	const u8 *b = buffer, *end = buffer + buffer_size;
 	int ret = -ENOMEM, nr_servers, i, j;

 	_enter("");

 	/* Check that it's a server list, v1 */
 	if (end - b < sizeof(*hdr) ||
 	    hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST ||
 	    hdr->hdr.version != 1) {
 		pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
 			  hdr->hdr.content, hdr->hdr.version, end - b);
 		ret = -EDESTADDRREQ;
 		goto dump;
 	}

 	nr_servers = hdr->nr_servers;

 	vllist = afs_alloc_vlserver_list(nr_servers);
 	if (!vllist)
 		return ERR_PTR(-ENOMEM);

 	vllist->source = (hdr->source < NR__dns_record_source) ?
 		hdr->source : NR__dns_record_source;
 	vllist->status = (hdr->status < NR__dns_lookup_status) ?
 		hdr->status : NR__dns_lookup_status;

 	read_lock(&cell->vl_servers_lock);
 	previous = afs_get_vlserverlist(
 		rcu_dereference_protected(cell->vl_servers,
 					  lockdep_is_held(&cell->vl_servers_lock)));
 	read_unlock(&cell->vl_servers_lock);

 	b += sizeof(*hdr);
 	while (end - b >= sizeof(bs)) {
 		bs.name_len	= afs_extract_le16(&b);
 		bs.priority	= afs_extract_le16(&b);
 		bs.weight	= afs_extract_le16(&b);
 		bs.port		= afs_extract_le16(&b);
 		bs.source	= *b++;
 		bs.status	= *b++;
 		bs.protocol	= *b++;
 		bs.nr_addrs	= *b++;

 		_debug("extract %u %u %u %u %u %u %*.*s",
 		       bs.name_len, bs.priority, bs.weight,
 		       bs.port, bs.protocol, bs.nr_addrs,
 		       bs.name_len, bs.name_len, b);

 		if (end - b < bs.name_len)
 			break;

 		ret = -EPROTONOSUPPORT;
 		if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
 			bs.protocol = DNS_SERVER_PROTOCOL_UDP;
 		} else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
 			_leave(" = [proto %u]", bs.protocol);
 			goto error;
 		}

 		if (bs.port == 0)
 			bs.port = AFS_VL_PORT;
 		if (bs.source > NR__dns_record_source)
 			bs.source = NR__dns_record_source;
 		if (bs.status > NR__dns_lookup_status)
 			bs.status = NR__dns_lookup_status;

 		/* See if we can update an old server record */
 		server = NULL;
 		for (i = 0; i < previous->nr_servers; i++) {
 			struct afs_vlserver *p = previous->servers[i].server;

 			if (p->name_len == bs.name_len &&
 			    p->port == bs.port &&
 			    strncasecmp(b, p->name, bs.name_len) == 0) {
 				server = afs_get_vlserver(p);
 				break;
 			}
 		}

 		if (!server) {
 			ret = -ENOMEM;
 			server = afs_alloc_vlserver(b, bs.name_len, bs.port);
 			if (!server)
 				goto error;
 		}

 		b += bs.name_len;

 		/* Extract the addresses - note that we can't skip this as we
 		 * have to advance the payload pointer.
 		 */
 		addrs = afs_extract_vl_addrs(&b, end, bs.nr_addrs, bs.port);
 		if (IS_ERR(addrs)) {
 			ret = PTR_ERR(addrs);
 			goto error_2;
 		}

 		if (vllist->nr_servers >= nr_servers) {
 			_debug("skip %u >= %u", vllist->nr_servers, nr_servers);
 			afs_put_addrlist(addrs);
 			afs_put_vlserver(cell->net, server);
 			continue;
 		}

 		addrs->source = bs.source;
 		addrs->status = bs.status;

 		if (addrs->nr_addrs == 0) {
 			afs_put_addrlist(addrs);
 			if (!rcu_access_pointer(server->addresses)) {
 				afs_put_vlserver(cell->net, server);
 				continue;
 			}
 		} else {
 			struct afs_addr_list *old = addrs;

 			write_lock(&server->lock);
 			old = rcu_replace_pointer(server->addresses, old,
 						  lockdep_is_held(&server->lock));
 			write_unlock(&server->lock);
 			afs_put_addrlist(old);
 		}


 		/* TODO: Might want to check for duplicates */

 		/* Insertion-sort by priority and weight */
 		for (j = 0; j < vllist->nr_servers; j++) {
 			if (bs.priority < vllist->servers[j].priority)
 				break; /* Lower preferable */
 			if (bs.priority == vllist->servers[j].priority &&
 			    bs.weight > vllist->servers[j].weight)
 				break; /* Higher preferable */
 		}

 		if (j < vllist->nr_servers) {
 			memmove(vllist->servers + j + 1,
 				vllist->servers + j,
 				(vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
 		}

 		clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);

 		vllist->servers[j].priority = bs.priority;
 		vllist->servers[j].weight = bs.weight;
 		vllist->servers[j].server = server;
 		vllist->nr_servers++;
 	}

 	if (b != end) {
 		_debug("parse error %zd", b - end);
 		goto error;
 	}

 	afs_put_vlserverlist(cell->net, previous);
 	_leave(" = ok [%u]", vllist->nr_servers);
 	return vllist;

 error_2:
 	afs_put_vlserver(cell->net, server);
 error:
 	afs_put_vlserverlist(cell->net, vllist);
 	afs_put_vlserverlist(cell->net, previous);
 dump:
 	if (ret != -ENOMEM) {
 		printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
 		print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
 	}
 	return ERR_PTR(ret);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* AFS vlserver list management.
	*
	* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*/

	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include "internal.h"

	struct afs_vlserver afs_alloc_vlserver(const char name, size_t name_len,
	unsigned short port)
	{
	struct afs_vlserver *vlserver;

	vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
	GFP_KERNEL);
	if (vlserver) {
	refcount_set(&vlserver->ref, 1);
	rwlock_init(&vlserver->lock);
	init_waitqueue_head(&vlserver->probe_wq);
	spin_lock_init(&vlserver->probe_lock);
	vlserver->rtt = UINT_MAX;
	vlserver->name_len = name_len;
	vlserver->port = port;
	memcpy(vlserver->name, name, name_len);
	}
	return vlserver;
	}

	static void afs_vlserver_rcu(struct rcu_head *rcu)
	{
	struct afs_vlserver *vlserver = container_of(rcu, struct afs_vlserver, rcu);

	afs_put_addrlist(rcu_access_pointer(vlserver->addresses));
	kfree_rcu(vlserver, rcu);
	}

	void afs_put_vlserver(struct afs_net net, struct afs_vlserver vlserver)
	{
	if (vlserver &&
	refcount_dec_and_test(&vlserver->ref))
	call_rcu(&vlserver->rcu, afs_vlserver_rcu);
	}

	struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
	{
	struct afs_vlserver_list *vllist;

	vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
	if (vllist) {
	refcount_set(&vllist->ref, 1);
	rwlock_init(&vllist->lock);
	}

	return vllist;
	}

	void afs_put_vlserverlist(struct afs_net net, struct afs_vlserver_list vllist)
	{
	if (vllist) {
	if (refcount_dec_and_test(&vllist->ref)) {
	int i;

	for (i = 0; i < vllist->nr_servers; i++) {
	afs_put_vlserver(net, vllist->servers[i].server);
	}
	kfree_rcu(vllist, rcu);
	}
	}
	}

	static u16 afs_extract_le16(const u8 **_b)
	{
	u16 val;

	val = (u16)(_b)++ << 0;
	val \|= (u16)(_b)++ << 8;
	return val;
	}

	/*
	* Build a VL server address list from a DNS queried server list.
	*/
	static struct afs_addr_list afs_extract_vl_addrs(const u8 _b, const u8 end,
	u8 nr_addrs, u16 port)
	{
	struct afs_addr_list *alist;
	const u8 b = _b;
	int ret = -EINVAL;

	alist = afs_alloc_addrlist(nr_addrs, VL_SERVICE, port);
	if (!alist)
	return ERR_PTR(-ENOMEM);
	if (nr_addrs == 0)
	return alist;

	for (; nr_addrs > 0 && end - b >= nr_addrs; nr_addrs--) {
	struct dns_server_list_v1_address hdr;
	__be32 x[4];

	hdr.address_type = *b++;

	switch (hdr.address_type) {
	case DNS_ADDRESS_IS_IPV4:
	if (end - b < 4) {
	_leave(" = -EINVAL [short inet]");
	goto error;
	}
	memcpy(x, b, 4);
	afs_merge_fs_addr4(alist, x[0], port);
	b += 4;
	break;

	case DNS_ADDRESS_IS_IPV6:
	if (end - b < 16) {
	_leave(" = -EINVAL [short inet6]");
	goto error;
	}
	memcpy(x, b, 16);
	afs_merge_fs_addr6(alist, x, port);
	b += 16;
	break;

	default:
	_leave(" = -EADDRNOTAVAIL [unknown af %u]",
	hdr.address_type);
	ret = -EADDRNOTAVAIL;
	goto error;
	}
	}

	/* Start with IPv6 if available. */
	if (alist->nr_ipv4 < alist->nr_addrs)
	alist->preferred = alist->nr_ipv4;

	*_b = b;
	return alist;

	error:
	*_b = b;
	afs_put_addrlist(alist);
	return ERR_PTR(ret);
	}

	/*
	* Build a VL server list from a DNS queried server list.
	*/
	struct afs_vlserver_list afs_extract_vlserver_list(struct afs_cell cell,
	const void *buffer,
	size_t buffer_size)
	{
	const struct dns_server_list_v1_header *hdr = buffer;
	struct dns_server_list_v1_server bs;
	struct afs_vlserver_list vllist, previous;
	struct afs_addr_list *addrs;
	struct afs_vlserver *server;
	const u8 b = buffer, end = buffer + buffer_size;
	int ret = -ENOMEM, nr_servers, i, j;

	_enter("");

	/* Check that it's a server list, v1 */
	if (end - b < sizeof(*hdr) \|\|
	hdr->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST \|\|
	hdr->hdr.version != 1) {
	pr_notice("kAFS: Got DNS record [%u,%u] len %zu\n",
	hdr->hdr.content, hdr->hdr.version, end - b);
	ret = -EDESTADDRREQ;
	goto dump;
	}

	nr_servers = hdr->nr_servers;

	vllist = afs_alloc_vlserver_list(nr_servers);
	if (!vllist)
	return ERR_PTR(-ENOMEM);

	vllist->source = (hdr->source < NR__dns_record_source) ?
	hdr->source : NR__dns_record_source;
	vllist->status = (hdr->status < NR__dns_lookup_status) ?
	hdr->status : NR__dns_lookup_status;

	read_lock(&cell->vl_servers_lock);
	previous = afs_get_vlserverlist(
	rcu_dereference_protected(cell->vl_servers,
	lockdep_is_held(&cell->vl_servers_lock)));
	read_unlock(&cell->vl_servers_lock);

	b += sizeof(*hdr);
	while (end - b >= sizeof(bs)) {
	bs.name_len = afs_extract_le16(&b);
	bs.priority = afs_extract_le16(&b);
	bs.weight = afs_extract_le16(&b);
	bs.port = afs_extract_le16(&b);
	bs.source = *b++;
	bs.status = *b++;
	bs.protocol = *b++;
	bs.nr_addrs = *b++;

	_debug("extract %u %u %u %u %u %u %.s",
	bs.name_len, bs.priority, bs.weight,
	bs.port, bs.protocol, bs.nr_addrs,
	bs.name_len, bs.name_len, b);

	if (end - b < bs.name_len)
	break;

	ret = -EPROTONOSUPPORT;
	if (bs.protocol == DNS_SERVER_PROTOCOL_UNSPECIFIED) {
	bs.protocol = DNS_SERVER_PROTOCOL_UDP;
	} else if (bs.protocol != DNS_SERVER_PROTOCOL_UDP) {
	_leave(" = [proto %u]", bs.protocol);
	goto error;
	}

	if (bs.port == 0)
	bs.port = AFS_VL_PORT;
	if (bs.source > NR__dns_record_source)
	bs.source = NR__dns_record_source;
	if (bs.status > NR__dns_lookup_status)
	bs.status = NR__dns_lookup_status;

	/* See if we can update an old server record */
	server = NULL;
	for (i = 0; i < previous->nr_servers; i++) {
	struct afs_vlserver *p = previous->servers[i].server;

	if (p->name_len == bs.name_len &&
	p->port == bs.port &&
	strncasecmp(b, p->name, bs.name_len) == 0) {
	server = afs_get_vlserver(p);
	break;
	}
	}

	if (!server) {
	ret = -ENOMEM;
	server = afs_alloc_vlserver(b, bs.name_len, bs.port);
	if (!server)
	goto error;
	}

	b += bs.name_len;

	/* Extract the addresses - note that we can't skip this as we
	* have to advance the payload pointer.
	*/
	addrs = afs_extract_vl_addrs(&b, end, bs.nr_addrs, bs.port);
	if (IS_ERR(addrs)) {
	ret = PTR_ERR(addrs);
	goto error_2;
	}

	if (vllist->nr_servers >= nr_servers) {
	_debug("skip %u >= %u", vllist->nr_servers, nr_servers);
	afs_put_addrlist(addrs);
	afs_put_vlserver(cell->net, server);
	continue;
	}

	addrs->source = bs.source;
	addrs->status = bs.status;

	if (addrs->nr_addrs == 0) {
	afs_put_addrlist(addrs);
	if (!rcu_access_pointer(server->addresses)) {
	afs_put_vlserver(cell->net, server);
	continue;
	}
	} else {
	struct afs_addr_list *old = addrs;

	write_lock(&server->lock);
	old = rcu_replace_pointer(server->addresses, old,
	lockdep_is_held(&server->lock));
	write_unlock(&server->lock);
	afs_put_addrlist(old);
	}


	/* TODO: Might want to check for duplicates */

	/* Insertion-sort by priority and weight */
	for (j = 0; j < vllist->nr_servers; j++) {
	if (bs.priority < vllist->servers[j].priority)
	break; /* Lower preferable */
	if (bs.priority == vllist->servers[j].priority &&
	bs.weight > vllist->servers[j].weight)
	break; /* Higher preferable */
	}

	if (j < vllist->nr_servers) {
	memmove(vllist->servers + j + 1,
	vllist->servers + j,
	(vllist->nr_servers - j) * sizeof(struct afs_vlserver_entry));
	}

	clear_bit(AFS_VLSERVER_FL_PROBED, &server->flags);

	vllist->servers[j].priority = bs.priority;
	vllist->servers[j].weight = bs.weight;
	vllist->servers[j].server = server;
	vllist->nr_servers++;
	}

	if (b != end) {
	_debug("parse error %zd", b - end);
	goto error;
	}

	afs_put_vlserverlist(cell->net, previous);
	_leave(" = ok [%u]", vllist->nr_servers);
	return vllist;

	error_2:
	afs_put_vlserver(cell->net, server);
	error:
	afs_put_vlserverlist(cell->net, vllist);
	afs_put_vlserverlist(cell->net, previous);
	dump:
	if (ret != -ENOMEM) {
	printk(KERN_DEBUG "DNS: at %zu\n", (const void *)b - buffer);
	print_hex_dump_bytes("DNS: ", DUMP_PREFIX_NONE, buffer, buffer_size);
	}
	return ERR_PTR(ret);
	}