1 files changed, 404 insertions, 0 deletions

diff --git a/fs/afs/addr_list.c b/fs/afs/addr_list.c
new file mode 100644
index 000000000..de1ae0bea
--- /dev/null
+++ b/fs/afs/addr_list.c
@@ -0,0 +1,404 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Server address list management
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#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))
+		kfree_rcu(alist, rcu);
+}
+
+/*
+ * 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(cell->net->net, "afsdb", cell->name, cell->name_len,
+			"srv=1", &result, _expiry, true);
+	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;
+}