diff options
Diffstat (limited to '')
-rw-r--r-- | fs/afs/addr_list.c | 404 |
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; +} |