/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include #include #include "alloc-util.h" #include "errno-util.h" #include "hostname-util.h" #include "local-addresses.h" #include "macro.h" #include "nss-util.h" #include "signal-util.h" #include "socket-util.h" #include "string-util.h" /* We use 127.0.0.2 as IPv4 address. This has the advantage over * 127.0.0.1 that it can be translated back to the local hostname. For * IPv6 we use ::1 which unfortunately will not translate back to the * hostname but instead something like "localhost" or so. */ #define LOCALADDRESS_IPV4 (htobe32(0x7F000002)) #define LOCALADDRESS_IPV6 &in6addr_loopback NSS_GETHOSTBYNAME_PROTOTYPES(myhostname); NSS_GETHOSTBYADDR_PROTOTYPES(myhostname); enum nss_status _nss_myhostname_gethostbyname4_r( const char *name, struct gaih_addrtuple **pat, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp) { struct gaih_addrtuple *r_tuple, *r_tuple_prev = NULL; _cleanup_free_ struct local_address *addresses = NULL; _cleanup_free_ char *hn = NULL; const char *canonical = NULL; int n_addresses = 0; uint32_t local_address_ipv4; size_t l, idx, ms; char *r_name; PROTECT_ERRNO; BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); assert(name); assert(pat); assert(buffer); assert(errnop); assert(h_errnop); if (is_localhost(name)) { /* We respond to 'localhost', so that /etc/hosts is optional */ canonical = "localhost"; local_address_ipv4 = htobe32(INADDR_LOOPBACK); } else if (is_gateway_hostname(name)) { n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses); if (n_addresses <= 0) goto not_found; canonical = "_gateway"; } else if (is_outbound_hostname(name)) { n_addresses = local_outbounds(NULL, 0, AF_UNSPEC, &addresses); if (n_addresses <= 0) goto not_found; canonical = "_outbound"; } else { hn = gethostname_malloc(); if (!hn) { UNPROTECT_ERRNO; *errnop = ENOMEM; *h_errnop = NO_RECOVERY; return NSS_STATUS_TRYAGAIN; } /* We respond to our local hostname, our hostname suffixed with a single dot. */ if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) goto not_found; n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses); if (n_addresses < 0) n_addresses = 0; canonical = hn; local_address_ipv4 = LOCALADDRESS_IPV4; } l = strlen(canonical); ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * (n_addresses > 0 ? n_addresses : 1 + socket_ipv6_is_enabled()); if (buflen < ms) { UNPROTECT_ERRNO; *errnop = ERANGE; *h_errnop = NETDB_INTERNAL; return NSS_STATUS_TRYAGAIN; } /* First, fill in hostname */ r_name = buffer; memcpy(r_name, canonical, l+1); idx = ALIGN(l+1); assert(n_addresses >= 0); if (n_addresses == 0) { /* Second, fill in IPv6 tuple */ if (socket_ipv6_is_enabled()) { r_tuple = (struct gaih_addrtuple*) (buffer + idx); r_tuple->next = r_tuple_prev; r_tuple->name = r_name; r_tuple->family = AF_INET6; memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16); r_tuple->scopeid = 0; idx += ALIGN(sizeof(struct gaih_addrtuple)); r_tuple_prev = r_tuple; } /* Third, fill in IPv4 tuple */ r_tuple = (struct gaih_addrtuple*) (buffer + idx); r_tuple->next = r_tuple_prev; r_tuple->name = r_name; r_tuple->family = AF_INET; *(uint32_t*) r_tuple->addr = local_address_ipv4; r_tuple->scopeid = 0; idx += ALIGN(sizeof(struct gaih_addrtuple)); r_tuple_prev = r_tuple; } /* Fourth, fill actual addresses in, but in backwards order */ for (int i = n_addresses; i > 0; i--) { struct local_address *a = addresses + i - 1; r_tuple = (struct gaih_addrtuple*) (buffer + idx); r_tuple->next = r_tuple_prev; r_tuple->name = r_name; r_tuple->family = a->family; r_tuple->scopeid = a->family == AF_INET6 && in6_addr_is_link_local(&a->address.in6) ? a->ifindex : 0; memcpy(r_tuple->addr, &a->address, 16); idx += ALIGN(sizeof(struct gaih_addrtuple)); r_tuple_prev = r_tuple; } /* Verify the size matches */ assert(idx == ms); /* Nscd expects us to store the first record in **pat. */ if (*pat) **pat = *r_tuple_prev; else *pat = r_tuple_prev; if (ttlp) *ttlp = 0; /* Explicitly reset both *h_errnop and h_errno to work around * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */ *h_errnop = NETDB_SUCCESS; h_errno = 0; return NSS_STATUS_SUCCESS; not_found: *h_errnop = HOST_NOT_FOUND; return NSS_STATUS_NOTFOUND; } static enum nss_status fill_in_hostent( const char *canonical, const char *additional, int af, struct local_address *addresses, unsigned n_addresses, uint32_t local_address_ipv4, struct hostent *result, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp, char **canonp) { size_t l_canonical, l_additional, idx, ms, alen; char *r_addr, *r_name, *r_aliases, *r_alias = NULL, *r_addr_list; struct local_address *a; unsigned n, c; assert(canonical); assert(IN_SET(af, AF_INET, AF_INET6)); assert(result); assert(buffer); assert(errnop); assert(h_errnop); PROTECT_ERRNO; alen = FAMILY_ADDRESS_SIZE(af); for (a = addresses, n = 0, c = 0; n < n_addresses; a++, n++) if (af == a->family) c++; l_canonical = strlen(canonical); l_additional = strlen_ptr(additional); ms = ALIGN(l_canonical+1)+ (additional ? ALIGN(l_additional+1) : 0) + sizeof(char*) + (additional ? sizeof(char*) : 0) + (c > 0 ? c : af == AF_INET ? 1 : socket_ipv6_is_enabled()) * ALIGN(alen) + (c > 0 ? c+1 : af == AF_INET ? 2 : (unsigned) socket_ipv6_is_enabled() + 1) * sizeof(char*); if (buflen < ms) { UNPROTECT_ERRNO; *errnop = ERANGE; *h_errnop = NETDB_INTERNAL; return NSS_STATUS_TRYAGAIN; } /* First, fill in hostnames */ r_name = buffer; memcpy(r_name, canonical, l_canonical+1); idx = ALIGN(l_canonical+1); if (additional) { r_alias = buffer + idx; memcpy(r_alias, additional, l_additional+1); idx += ALIGN(l_additional+1); } /* Second, create aliases array */ r_aliases = buffer + idx; if (additional) { ((char**) r_aliases)[0] = r_alias; ((char**) r_aliases)[1] = NULL; idx += 2*sizeof(char*); } else { ((char**) r_aliases)[0] = NULL; idx += sizeof(char*); } /* Third, add addresses */ r_addr = buffer + idx; if (c > 0) { unsigned i = 0; for (a = addresses, n = 0; n < n_addresses; a++, n++) { if (af != a->family) continue; memcpy(r_addr + i*ALIGN(alen), &a->address, alen); i++; } assert(i == c); idx += c*ALIGN(alen); } else if (af == AF_INET) { *(uint32_t*) r_addr = local_address_ipv4; idx += ALIGN(alen); } else if (socket_ipv6_is_enabled()) { memcpy(r_addr, LOCALADDRESS_IPV6, 16); idx += ALIGN(alen); } /* Fourth, add address pointer array */ r_addr_list = buffer + idx; if (c > 0) { unsigned i; for (i = 0; i < c; i++) ((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen); ((char**) r_addr_list)[i] = NULL; idx += (c+1) * sizeof(char*); } else if (af == AF_INET || socket_ipv6_is_enabled()) { ((char**) r_addr_list)[0] = r_addr; ((char**) r_addr_list)[1] = NULL; idx += 2 * sizeof(char*); } else { ((char**) r_addr_list)[0] = NULL; idx += sizeof(char*); } /* Verify the size matches */ assert(idx == ms); result->h_name = r_name; result->h_aliases = (char**) r_aliases; result->h_addrtype = af; result->h_length = alen; result->h_addr_list = (char**) r_addr_list; if (ttlp) *ttlp = 0; if (canonp) *canonp = r_name; /* Explicitly reset both *h_errnop and h_errno to work around * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */ *h_errnop = NETDB_SUCCESS; h_errno = 0; return NSS_STATUS_SUCCESS; } enum nss_status _nss_myhostname_gethostbyname3_r( const char *name, int af, struct hostent *host, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp, char **canonp) { _cleanup_free_ struct local_address *addresses = NULL; const char *canonical, *additional = NULL; _cleanup_free_ char *hn = NULL; uint32_t local_address_ipv4 = 0; int n_addresses = 0; PROTECT_ERRNO; BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); assert(name); assert(host); assert(buffer); assert(errnop); assert(h_errnop); if (af == AF_UNSPEC) af = AF_INET; if (!IN_SET(af, AF_INET, AF_INET6)) { UNPROTECT_ERRNO; *errnop = EAFNOSUPPORT; *h_errnop = NO_DATA; return NSS_STATUS_UNAVAIL; } if (af == AF_INET6 && !socket_ipv6_is_enabled()) goto not_found; if (is_localhost(name)) { canonical = "localhost"; local_address_ipv4 = htobe32(INADDR_LOOPBACK); } else if (is_gateway_hostname(name)) { n_addresses = local_gateways(NULL, 0, af, &addresses); if (n_addresses <= 0) goto not_found; canonical = "_gateway"; } else if (is_outbound_hostname(name)) { n_addresses = local_outbounds(NULL, 0, af, &addresses); if (n_addresses <= 0) goto not_found; canonical = "_outbound"; } else { hn = gethostname_malloc(); if (!hn) { UNPROTECT_ERRNO; *errnop = ENOMEM; *h_errnop = NO_RECOVERY; return NSS_STATUS_TRYAGAIN; } if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) goto not_found; n_addresses = local_addresses(NULL, 0, af, &addresses); if (n_addresses < 0) n_addresses = 0; canonical = hn; additional = n_addresses <= 0 && af == AF_INET6 ? "localhost" : NULL; local_address_ipv4 = LOCALADDRESS_IPV4; } UNPROTECT_ERRNO; return fill_in_hostent( canonical, additional, af, addresses, n_addresses, local_address_ipv4, host, buffer, buflen, errnop, h_errnop, ttlp, canonp); not_found: *h_errnop = HOST_NOT_FOUND; return NSS_STATUS_NOTFOUND; } enum nss_status _nss_myhostname_gethostbyaddr2_r( const void* addr, socklen_t len, int af, struct hostent *host, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp) { const char *canonical = NULL, *additional = NULL; uint32_t local_address_ipv4 = LOCALADDRESS_IPV4; _cleanup_free_ struct local_address *addresses = NULL; _cleanup_free_ char *hn = NULL; int n_addresses = 0; struct local_address *a; bool additional_from_hostname = false; unsigned n; PROTECT_ERRNO; BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); assert(addr); assert(host); assert(buffer); assert(errnop); assert(h_errnop); if (!IN_SET(af, AF_INET, AF_INET6)) { UNPROTECT_ERRNO; *errnop = EAFNOSUPPORT; *h_errnop = NO_DATA; return NSS_STATUS_UNAVAIL; } if (len != FAMILY_ADDRESS_SIZE(af)) { UNPROTECT_ERRNO; *errnop = EINVAL; *h_errnop = NO_RECOVERY; return NSS_STATUS_UNAVAIL; } if (af == AF_INET) { if ((*(uint32_t*) addr) == LOCALADDRESS_IPV4) goto found; if ((*(uint32_t*) addr) == htobe32(INADDR_LOOPBACK)) { canonical = "localhost"; local_address_ipv4 = htobe32(INADDR_LOOPBACK); goto found; } } else { assert(af == AF_INET6); if (!socket_ipv6_is_enabled()) goto not_found; if (memcmp(addr, LOCALADDRESS_IPV6, 16) == 0) { canonical = "localhost"; additional_from_hostname = true; goto found; } } n_addresses = local_addresses(NULL, 0, af, &addresses); for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) goto found; addresses = mfree(addresses); n_addresses = local_gateways(NULL, 0, af, &addresses); for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) { canonical = "_gateway"; goto found; } not_found: *h_errnop = HOST_NOT_FOUND; return NSS_STATUS_NOTFOUND; found: if (!canonical || additional_from_hostname) { hn = gethostname_malloc(); if (!hn) { UNPROTECT_ERRNO; *errnop = ENOMEM; *h_errnop = NO_RECOVERY; return NSS_STATUS_TRYAGAIN; } if (!canonical) canonical = hn; else additional = hn; } UNPROTECT_ERRNO; return fill_in_hostent( canonical, additional, af, addresses, n_addresses, local_address_ipv4, host, buffer, buflen, errnop, h_errnop, ttlp, NULL); } NSS_GETHOSTBYNAME_FALLBACKS(myhostname); NSS_GETHOSTBYADDR_FALLBACKS(myhostname);