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

 /* Server address list management
  *
  * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public Licence
  * as published by the Free Software Foundation; either version
  * 2 of the Licence, or (at your option) any later version.
  */

 #include <linux/slab.h>
 #include <linux/ctype.h>
 #include <linux/dns_resolver.h>
 #include <linux/inet.h>
 #include <keys/rxrpc-type.h>
 #include "internal.h"
 #include "afs_fs.h"

 /*
  * Release an address list.
  */
 void afs_put_addrlist(struct afs_addr_list *alist)
 {
 	if (alist && refcount_dec_and_test(&alist->usage))
 		call_rcu(&alist->rcu, (rcu_callback_t)kfree);
 }

 /*
  * Allocate an address list.
  */
 struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
 					 unsigned short service,
 					 unsigned short port)
 {
 	struct afs_addr_list *alist;
 	unsigned int i;

 	_enter("%u,%u,%u", nr, service, port);

 	if (nr > AFS_MAX_ADDRESSES)
 		nr = AFS_MAX_ADDRESSES;

 	alist = kzalloc(struct_size(alist, addrs, nr), GFP_KERNEL);
 	if (!alist)
 		return NULL;

 	refcount_set(&alist->usage, 1);
 	alist->max_addrs = nr;

 	for (i = 0; i < nr; i++) {
 		struct sockaddr_rxrpc *srx = &alist->addrs[i];
 		srx->srx_family			= AF_RXRPC;
 		srx->srx_service		= service;
 		srx->transport_type		= SOCK_DGRAM;
 		srx->transport_len		= sizeof(srx->transport.sin6);
 		srx->transport.sin6.sin6_family	= AF_INET6;
 		srx->transport.sin6.sin6_port	= htons(port);
 	}

 	return alist;
 }

 /*
  * Parse a text string consisting of delimited addresses.
  */
 struct afs_vlserver_list *afs_parse_text_addrs(struct afs_net *net,
 					       const char *text, size_t len,
 					       char delim,
 					       unsigned short service,
 					       unsigned short port)
 {
 	struct afs_vlserver_list *vllist;
 	struct afs_addr_list *alist;
 	const char *p, *end = text + len;
 	const char *problem;
 	unsigned int nr = 0;
 	int ret = -ENOMEM;

 	_enter("%*.*s,%c", (int)len, (int)len, text, delim);

 	if (!len) {
 		_leave(" = -EDESTADDRREQ [empty]");
 		return ERR_PTR(-EDESTADDRREQ);
 	}

 	if (delim == ':' && (memchr(text, ',', len) || !memchr(text, '.', len)))
 		delim = ',';

 	/* Count the addresses */
 	p = text;
 	do {
 		if (!*p) {
 			problem = "nul";
 			goto inval;
 		}
 		if (*p == delim)
 			continue;
 		nr++;
 		if (*p == '[') {
 			p++;
 			if (p == end) {
 				problem = "brace1";
 				goto inval;
 			}
 			p = memchr(p, ']', end - p);
 			if (!p) {
 				problem = "brace2";
 				goto inval;
 			}
 			p++;
 			if (p >= end)
 				break;
 		}

 		p = memchr(p, delim, end - p);
 		if (!p)
 			break;
 		p++;
 	} while (p < end);

 	_debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);

 	vllist = afs_alloc_vlserver_list(1);
 	if (!vllist)
 		return ERR_PTR(-ENOMEM);

 	vllist->nr_servers = 1;
 	vllist->servers[0].server = afs_alloc_vlserver("<dummy>", 7, AFS_VL_PORT);
 	if (!vllist->servers[0].server)
 		goto error_vl;

 	alist = afs_alloc_addrlist(nr, service, AFS_VL_PORT);
 	if (!alist)
 		goto error;

 	/* Extract the addresses */
 	p = text;
 	do {
 		const char *q, *stop;
 		unsigned int xport = port;
 		__be32 x[4];
 		int family;

 		if (*p == delim) {
 			p++;
 			continue;
 		}

 		if (*p == '[') {
 			p++;
 			q = memchr(p, ']', end - p);
 		} else {
 			for (q = p; q < end; q++)
 				if (*q == '+' || *q == delim)
 					break;
 		}

 		if (in4_pton(p, q - p, (u8 *)&x[0], -1, &stop)) {
 			family = AF_INET;
 		} else if (in6_pton(p, q - p, (u8 *)x, -1, &stop)) {
 			family = AF_INET6;
 		} else {
 			problem = "family";
 			goto bad_address;
 		}

 		p = q;
 		if (stop != p) {
 			problem = "nostop";
 			goto bad_address;
 		}

 		if (q < end && *q == ']')
 			p++;

 		if (p < end) {
 			if (*p == '+') {
 				/* Port number specification "+1234" */
 				xport = 0;
 				p++;
 				if (p >= end || !isdigit(*p)) {
 					problem = "port";
 					goto bad_address;
 				}
 				do {
 					xport *= 10;
 					xport += *p - '0';
 					if (xport > 65535) {
 						problem = "pval";
 						goto bad_address;
 					}
 					p++;
 				} while (p < end && isdigit(*p));
 			} else if (*p == delim) {
 				p++;
 			} else {
 				problem = "weird";
 				goto bad_address;
 			}
 		}

 		if (family == AF_INET)
 			afs_merge_fs_addr4(alist, x[0], xport);
 		else
 			afs_merge_fs_addr6(alist, x, xport);

 	} while (p < end);

 	rcu_assign_pointer(vllist->servers[0].server->addresses, alist);
 	_leave(" = [nr %u]", alist->nr_addrs);
 	return vllist;

 inval:
 	_leave(" = -EINVAL [%s %zu %*.*s]",
 	       problem, p - text, (int)len, (int)len, text);
 	return ERR_PTR(-EINVAL);
 bad_address:
 	_leave(" = -EINVAL [%s %zu %*.*s]",
 	       problem, p - text, (int)len, (int)len, text);
 	ret = -EINVAL;
 error:
 	afs_put_addrlist(alist);
 error_vl:
 	afs_put_vlserverlist(net, vllist);
 	return ERR_PTR(ret);
 }

 /*
  * Compare old and new address lists to see if there's been any change.
  * - How to do this in better than O(Nlog(N)) time?
  *   - We don't really want to sort the address list, but would rather take the
  *     list as we got it so as not to undo record rotation by the DNS server.
  */
 #if 0
 static int afs_cmp_addr_list(const struct afs_addr_list *a1,
 			     const struct afs_addr_list *a2)
 {
 }
 #endif

 /*
  * Perform a DNS query for VL servers and build a up an address list.
  */
 struct afs_vlserver_list *afs_dns_query(struct afs_cell *cell, time64_t *_expiry)
 {
 	struct afs_vlserver_list *vllist;
 	char *result = NULL;
 	int ret;

 	_enter("%s", cell->name);

 	ret = dns_query("afsdb", cell->name, cell->name_len, "srv=1",
 			&result, _expiry);
 	if (ret < 0) {
 		_leave(" = %d [dns]", ret);
 		return ERR_PTR(ret);
 	}

 	if (*_expiry == 0)
 		*_expiry = ktime_get_real_seconds() + 60;

 	if (ret > 1 && result[0] == 0)
 		vllist = afs_extract_vlserver_list(cell, result, ret);
 	else
 		vllist = afs_parse_text_addrs(cell->net, result, ret, ',',
 					      VL_SERVICE, AFS_VL_PORT);
 	kfree(result);
 	if (IS_ERR(vllist) && vllist != ERR_PTR(-ENOMEM))
 		pr_err("Failed to parse DNS data %ld\n", PTR_ERR(vllist));

 	return vllist;
 }

 /*
  * Merge an IPv4 entry into a fileserver address list.
  */
 void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
 {
 	struct sockaddr_rxrpc *srx;
 	u32 addr = ntohl(xdr);
 	int i;

 	if (alist->nr_addrs >= alist->max_addrs)
 		return;

 	for (i = 0; i < alist->nr_ipv4; i++) {
 		struct sockaddr_in *a = &alist->addrs[i].transport.sin;
 		u32 a_addr = ntohl(a->sin_addr.s_addr);
 		u16 a_port = ntohs(a->sin_port);

 		if (addr == a_addr && port == a_port)
 			return;
 		if (addr == a_addr && port < a_port)
 			break;
 		if (addr < a_addr)
 			break;
 	}

 	if (i < alist->nr_addrs)
 		memmove(alist->addrs + i + 1,
 			alist->addrs + i,
 			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));

 	srx = &alist->addrs[i];
 	srx->srx_family = AF_RXRPC;
 	srx->transport_type = SOCK_DGRAM;
 	srx->transport_len = sizeof(srx->transport.sin);
 	srx->transport.sin.sin_family = AF_INET;
 	srx->transport.sin.sin_port = htons(port);
 	srx->transport.sin.sin_addr.s_addr = xdr;
 	alist->nr_ipv4++;
 	alist->nr_addrs++;
 }

 /*
  * Merge an IPv6 entry into a fileserver address list.
  */
 void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
 {
 	struct sockaddr_rxrpc *srx;
 	int i, diff;

 	if (alist->nr_addrs >= alist->max_addrs)
 		return;

 	for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
 		struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
 		u16 a_port = ntohs(a->sin6_port);

 		diff = memcmp(xdr, &a->sin6_addr, 16);
 		if (diff == 0 && port == a_port)
 			return;
 		if (diff == 0 && port < a_port)
 			break;
 		if (diff < 0)
 			break;
 	}

 	if (i < alist->nr_addrs)
 		memmove(alist->addrs + i + 1,
 			alist->addrs + i,
 			sizeof(alist->addrs[0]) * (alist->nr_addrs - i));

 	srx = &alist->addrs[i];
 	srx->srx_family = AF_RXRPC;
 	srx->transport_type = SOCK_DGRAM;
 	srx->transport_len = sizeof(srx->transport.sin6);
 	srx->transport.sin6.sin6_family = AF_INET6;
 	srx->transport.sin6.sin6_port = htons(port);
 	memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
 	alist->nr_addrs++;
 }

 /*
  * Get an address to try.
  */
 bool afs_iterate_addresses(struct afs_addr_cursor *ac)
 {
 	unsigned long set, failed;
 	int index;

 	if (!ac->alist)
 		return false;

 	set = ac->alist->responded;
 	failed = ac->alist->failed;
 	_enter("%lx-%lx-%lx,%d", set, failed, ac->tried, ac->index);

 	ac->nr_iterations++;

 	set &= ~(failed | ac->tried);

 	if (!set)
 		return false;

 	index = READ_ONCE(ac->alist->preferred);
 	if (test_bit(index, &set))
 		goto selected;

 	index = __ffs(set);

 selected:
 	ac->index = index;
 	set_bit(index, &ac->tried);
 	ac->responded = false;
 	return true;
 }

 /*
  * Release an address list cursor.
  */
 int afs_end_cursor(struct afs_addr_cursor *ac)
 {
 	struct afs_addr_list *alist;

 	alist = ac->alist;
 	if (alist) {
 		if (ac->responded &&
 		    ac->index != alist->preferred &&
 		    test_bit(ac->alist->preferred, &ac->tried))
 			WRITE_ONCE(alist->preferred, ac->index);
 		afs_put_addrlist(alist);
 		ac->alist = NULL;
 	}

 	return ac->error;
 }
	/* Server address list management
	*
	* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public Licence
	* as published by the Free Software Foundation; either version
	* 2 of the Licence, or (at your option) any later version.
	*/

	#include <linux/slab.h>
	#include <linux/ctype.h>
	#include <linux/dns_resolver.h>
	#include <linux/inet.h>
	#include <keys/rxrpc-type.h>
	#include "internal.h"
	#include "afs_fs.h"

	/*
	* Release an address list.
	*/
	void afs_put_addrlist(struct afs_addr_list *alist)
	{
	if (alist && refcount_dec_and_test(&alist->usage))
	call_rcu(&alist->rcu, (rcu_callback_t)kfree);
	}

	/*
	* Allocate an address list.
	*/
	struct afs_addr_list *afs_alloc_addrlist(unsigned int nr,
	unsigned short service,
	unsigned short port)
	{
	struct afs_addr_list *alist;
	unsigned int i;

	_enter("%u,%u,%u", nr, service, port);

	if (nr > AFS_MAX_ADDRESSES)
	nr = AFS_MAX_ADDRESSES;

	alist = kzalloc(struct_size(alist, addrs, nr), GFP_KERNEL);
	if (!alist)
	return NULL;

	refcount_set(&alist->usage, 1);
	alist->max_addrs = nr;

	for (i = 0; i < nr; i++) {
	struct sockaddr_rxrpc *srx = &alist->addrs[i];
	srx->srx_family = AF_RXRPC;
	srx->srx_service = service;
	srx->transport_type = SOCK_DGRAM;
	srx->transport_len = sizeof(srx->transport.sin6);
	srx->transport.sin6.sin6_family = AF_INET6;
	srx->transport.sin6.sin6_port = htons(port);
	}

	return alist;
	}

	/*
	* Parse a text string consisting of delimited addresses.
	*/
	struct afs_vlserver_list afs_parse_text_addrs(struct afs_net net,
	const char *text, size_t len,
	char delim,
	unsigned short service,
	unsigned short port)
	{
	struct afs_vlserver_list *vllist;
	struct afs_addr_list *alist;
	const char p, end = text + len;
	const char *problem;
	unsigned int nr = 0;
	int ret = -ENOMEM;

	_enter("%.s,%c", (int)len, (int)len, text, delim);

	if (!len) {
	_leave(" = -EDESTADDRREQ [empty]");
	return ERR_PTR(-EDESTADDRREQ);
	}

	if (delim == ':' && (memchr(text, ',', len) \|\| !memchr(text, '.', len)))
	delim = ',';

	/* Count the addresses */
	p = text;
	do {
	if (!*p) {
	problem = "nul";
	goto inval;
	}
	if (*p == delim)
	continue;
	nr++;
	if (*p == '[') {
	p++;
	if (p == end) {
	problem = "brace1";
	goto inval;
	}
	p = memchr(p, ']', end - p);
	if (!p) {
	problem = "brace2";
	goto inval;
	}
	p++;
	if (p >= end)
	break;
	}

	p = memchr(p, delim, end - p);
	if (!p)
	break;
	p++;
	} while (p < end);

	_debug("%u/%u addresses", nr, AFS_MAX_ADDRESSES);

	vllist = afs_alloc_vlserver_list(1);
	if (!vllist)
	return ERR_PTR(-ENOMEM);

	vllist->nr_servers = 1;
	vllist->servers[0].server = afs_alloc_vlserver("<dummy>", 7, AFS_VL_PORT);
	if (!vllist->servers[0].server)
	goto error_vl;

	alist = afs_alloc_addrlist(nr, service, AFS_VL_PORT);
	if (!alist)
	goto error;

	/* Extract the addresses */
	p = text;
	do {
	const char q, stop;
	unsigned int xport = port;
	__be32 x[4];
	int family;

	if (*p == delim) {
	p++;
	continue;
	}

	if (*p == '[') {
	p++;
	q = memchr(p, ']', end - p);
	} else {
	for (q = p; q < end; q++)
	if (q == '+' \|\| q == delim)
	break;
	}

	if (in4_pton(p, q - p, (u8 *)&x[0], -1, &stop)) {
	family = AF_INET;
	} else if (in6_pton(p, q - p, (u8 *)x, -1, &stop)) {
	family = AF_INET6;
	} else {
	problem = "family";
	goto bad_address;
	}

	p = q;
	if (stop != p) {
	problem = "nostop";
	goto bad_address;
	}

	if (q < end && *q == ']')
	p++;

	if (p < end) {
	if (*p == '+') {
	/* Port number specification "+1234" */
	xport = 0;
	p++;
	if (p >= end \|\| !isdigit(*p)) {
	problem = "port";
	goto bad_address;
	}
	do {
	xport *= 10;
	xport += *p - '0';
	if (xport > 65535) {
	problem = "pval";
	goto bad_address;
	}
	p++;
	} while (p < end && isdigit(*p));
	} else if (*p == delim) {
	p++;
	} else {
	problem = "weird";
	goto bad_address;
	}
	}

	if (family == AF_INET)
	afs_merge_fs_addr4(alist, x[0], xport);
	else
	afs_merge_fs_addr6(alist, x, xport);

	} while (p < end);

	rcu_assign_pointer(vllist->servers[0].server->addresses, alist);
	_leave(" = [nr %u]", alist->nr_addrs);
	return vllist;

	inval:
	_leave(" = -EINVAL [%s %zu %.s]",
	problem, p - text, (int)len, (int)len, text);
	return ERR_PTR(-EINVAL);
	bad_address:
	_leave(" = -EINVAL [%s %zu %.s]",
	problem, p - text, (int)len, (int)len, text);
	ret = -EINVAL;
	error:
	afs_put_addrlist(alist);
	error_vl:
	afs_put_vlserverlist(net, vllist);
	return ERR_PTR(ret);
	}

	/*
	* Compare old and new address lists to see if there's been any change.
	* - How to do this in better than O(Nlog(N)) time?
	* - We don't really want to sort the address list, but would rather take the
	* list as we got it so as not to undo record rotation by the DNS server.
	*/
	#if 0
	static int afs_cmp_addr_list(const struct afs_addr_list *a1,
	const struct afs_addr_list *a2)
	{
	}
	#endif

	/*
	* Perform a DNS query for VL servers and build a up an address list.
	*/
	struct afs_vlserver_list afs_dns_query(struct afs_cell cell, time64_t *_expiry)
	{
	struct afs_vlserver_list *vllist;
	char *result = NULL;
	int ret;

	_enter("%s", cell->name);

	ret = dns_query("afsdb", cell->name, cell->name_len, "srv=1",
	&result, _expiry);
	if (ret < 0) {
	_leave(" = %d [dns]", ret);
	return ERR_PTR(ret);
	}

	if (*_expiry == 0)
	*_expiry = ktime_get_real_seconds() + 60;

	if (ret > 1 && result[0] == 0)
	vllist = afs_extract_vlserver_list(cell, result, ret);
	else
	vllist = afs_parse_text_addrs(cell->net, result, ret, ',',
	VL_SERVICE, AFS_VL_PORT);
	kfree(result);
	if (IS_ERR(vllist) && vllist != ERR_PTR(-ENOMEM))
	pr_err("Failed to parse DNS data %ld\n", PTR_ERR(vllist));

	return vllist;
	}

	/*
	* Merge an IPv4 entry into a fileserver address list.
	*/
	void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
	{
	struct sockaddr_rxrpc *srx;
	u32 addr = ntohl(xdr);
	int i;

	if (alist->nr_addrs >= alist->max_addrs)
	return;

	for (i = 0; i < alist->nr_ipv4; i++) {
	struct sockaddr_in *a = &alist->addrs[i].transport.sin;
	u32 a_addr = ntohl(a->sin_addr.s_addr);
	u16 a_port = ntohs(a->sin_port);

	if (addr == a_addr && port == a_port)
	return;
	if (addr == a_addr && port < a_port)
	break;
	if (addr < a_addr)
	break;
	}

	if (i < alist->nr_addrs)
	memmove(alist->addrs + i + 1,
	alist->addrs + i,
	sizeof(alist->addrs[0]) * (alist->nr_addrs - i));

	srx = &alist->addrs[i];
	srx->srx_family = AF_RXRPC;
	srx->transport_type = SOCK_DGRAM;
	srx->transport_len = sizeof(srx->transport.sin);
	srx->transport.sin.sin_family = AF_INET;
	srx->transport.sin.sin_port = htons(port);
	srx->transport.sin.sin_addr.s_addr = xdr;
	alist->nr_ipv4++;
	alist->nr_addrs++;
	}

	/*
	* Merge an IPv6 entry into a fileserver address list.
	*/
	void afs_merge_fs_addr6(struct afs_addr_list alist, __be32 xdr, u16 port)
	{
	struct sockaddr_rxrpc *srx;
	int i, diff;

	if (alist->nr_addrs >= alist->max_addrs)
	return;

	for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
	struct sockaddr_in6 *a = &alist->addrs[i].transport.sin6;
	u16 a_port = ntohs(a->sin6_port);

	diff = memcmp(xdr, &a->sin6_addr, 16);
	if (diff == 0 && port == a_port)
	return;
	if (diff == 0 && port < a_port)
	break;
	if (diff < 0)
	break;
	}

	if (i < alist->nr_addrs)
	memmove(alist->addrs + i + 1,
	alist->addrs + i,
	sizeof(alist->addrs[0]) * (alist->nr_addrs - i));

	srx = &alist->addrs[i];
	srx->srx_family = AF_RXRPC;
	srx->transport_type = SOCK_DGRAM;
	srx->transport_len = sizeof(srx->transport.sin6);
	srx->transport.sin6.sin6_family = AF_INET6;
	srx->transport.sin6.sin6_port = htons(port);
	memcpy(&srx->transport.sin6.sin6_addr, xdr, 16);
	alist->nr_addrs++;
	}

	/*
	* Get an address to try.
	*/
	bool afs_iterate_addresses(struct afs_addr_cursor *ac)
	{
	unsigned long set, failed;
	int index;

	if (!ac->alist)
	return false;

	set = ac->alist->responded;
	failed = ac->alist->failed;
	_enter("%lx-%lx-%lx,%d", set, failed, ac->tried, ac->index);

	ac->nr_iterations++;

	set &= ~(failed \| ac->tried);

	if (!set)
	return false;

	index = READ_ONCE(ac->alist->preferred);
	if (test_bit(index, &set))
	goto selected;

	index = __ffs(set);

	selected:
	ac->index = index;
	set_bit(index, &ac->tried);
	ac->responded = false;
	return true;
	}

	/*
	* Release an address list cursor.
	*/
	int afs_end_cursor(struct afs_addr_cursor *ac)
	{
	struct afs_addr_list *alist;

	alist = ac->alist;
	if (alist) {
	if (ac->responded &&
	ac->index != alist->preferred &&
	test_bit(ac->alist->preferred, &ac->tried))
	WRITE_ONCE(alist->preferred, ac->index);
	afs_put_addrlist(alist);
	ac->alist = NULL;
	}

	return ac->error;
	}