// 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); }