/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include #include #include #include #include "env-util.h" #include "errno-util.h" #include "in-addr-util.h" #include "macro.h" #include "nss-util.h" #include "resolved-def.h" #include "signal-util.h" #include "string-util.h" #include "strv.h" #include "varlink.h" static JsonDispatchFlags json_dispatch_flags = 0; static void setup_logging(void) { log_parse_environment_variables(); if (DEBUG_LOGGING) json_dispatch_flags = JSON_LOG; } static void setup_logging_once(void) { static pthread_once_t once = PTHREAD_ONCE_INIT; assert_se(pthread_once(&once, setup_logging) == 0); } #define NSS_ENTRYPOINT_BEGIN \ BLOCK_SIGNALS(NSS_SIGNALS_BLOCK); \ setup_logging_once() NSS_GETHOSTBYNAME_PROTOTYPES(resolve); NSS_GETHOSTBYADDR_PROTOTYPES(resolve); static bool error_shall_fallback(const char *error_id) { /* The Varlink errors where we shall signal "please fallback" back to the NSS stack, so that some * fallback module can be loaded. (These are mostly all Varlink-internal errors, as apparently we * then were unable to even do IPC with systemd-resolved.) */ return STR_IN_SET(error_id, VARLINK_ERROR_DISCONNECTED, VARLINK_ERROR_TIMEOUT, VARLINK_ERROR_PROTOCOL, VARLINK_ERROR_INTERFACE_NOT_FOUND, VARLINK_ERROR_METHOD_NOT_FOUND, VARLINK_ERROR_METHOD_NOT_IMPLEMENTED); } static bool error_shall_try_again(const char *error_id) { /* The Varlink errors where we shall signal "can't answer now but might be able to later" back to the * NSS stack. These are all errors that indicate lack of configuration or network problems. */ return STR_IN_SET(error_id, "io.systemd.Resolve.NoNameServers", "io.systemd.Resolve.QueryTimedOut", "io.systemd.Resolve.MaxAttemptsReached", "io.systemd.Resolve.NetworkDown"); } static int connect_to_resolved(Varlink **ret) { _cleanup_(varlink_unrefp) Varlink *link = NULL; int r; r = varlink_connect_address(&link, "/run/systemd/resolve/io.systemd.Resolve"); if (r < 0) return r; r = varlink_set_relative_timeout(link, SD_RESOLVED_QUERY_TIMEOUT_USEC); if (r < 0) return r; *ret = TAKE_PTR(link); return 0; } static uint32_t ifindex_to_scopeid(int family, const void *a, int ifindex) { struct in6_addr in6; if (family != AF_INET6 || ifindex == 0) return 0; /* Some apps can't deal with the scope ID attached to non-link-local addresses. Hence, let's suppress that. */ assert(sizeof(in6) == FAMILY_ADDRESS_SIZE(AF_INET6)); memcpy(&in6, a, sizeof(struct in6_addr)); return in6_addr_is_link_local(&in6) ? ifindex : 0; } static int json_dispatch_ifindex(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata) { int *ifi = userdata; int64_t t; assert(variant); assert(ifi); if (!json_variant_is_integer(variant)) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not an integer.", strna(name)); t = json_variant_integer(variant); if (t > INT_MAX) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is out of bounds for an interface index.", strna(name)); *ifi = (int) t; return 0; } static int json_dispatch_family(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata) { int *family = userdata; int64_t t; assert(variant); assert(family); if (!json_variant_is_integer(variant)) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not an integer.", strna(name)); t = json_variant_integer(variant); if (t < 0 || t > INT_MAX) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not a valid family.", strna(name)); *family = (int) t; return 0; } typedef struct ResolveHostnameReply { JsonVariant *addresses; char *name; uint64_t flags; } ResolveHostnameReply; static void resolve_hostname_reply_destroy(ResolveHostnameReply *p) { assert(p); json_variant_unref(p->addresses); free(p->name); } static const JsonDispatch resolve_hostname_reply_dispatch_table[] = { { "addresses", JSON_VARIANT_ARRAY, json_dispatch_variant, offsetof(ResolveHostnameReply, addresses), JSON_MANDATORY }, { "name", JSON_VARIANT_STRING, json_dispatch_string, offsetof(ResolveHostnameReply, name), 0 }, { "flags", JSON_VARIANT_UNSIGNED, json_dispatch_uint64, offsetof(ResolveHostnameReply, flags), 0 }, {} }; typedef struct AddressParameters { int ifindex; int family; union in_addr_union address; size_t address_size; } AddressParameters; static int json_dispatch_address(const char *name, JsonVariant *variant, JsonDispatchFlags flags, void *userdata) { AddressParameters *p = userdata; union in_addr_union buf = {}; JsonVariant *i; size_t n, k = 0; assert(variant); assert(p); if (!json_variant_is_array(variant)) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is not an array.", strna(name)); n = json_variant_elements(variant); if (!IN_SET(n, 4, 16)) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "JSON field '%s' is array of unexpected size.", strna(name)); JSON_VARIANT_ARRAY_FOREACH(i, variant) { int64_t b; if (!json_variant_is_integer(i)) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "Element %zu of JSON field '%s' is not an integer.", k, strna(name)); b = json_variant_integer(i); if (b < 0 || b > 0xff) return json_log(variant, flags, SYNTHETIC_ERRNO(EINVAL), "Element %zu of JSON field '%s' is out of range 0…255.", k, strna(name)); buf.bytes[k++] = (uint8_t) b; } p->address = buf; p->address_size = k; return 0; } static const JsonDispatch address_parameters_dispatch_table[] = { { "ifindex", JSON_VARIANT_INTEGER, json_dispatch_ifindex, offsetof(AddressParameters, ifindex), 0 }, { "family", JSON_VARIANT_INTEGER, json_dispatch_family, offsetof(AddressParameters, family), JSON_MANDATORY }, { "address", JSON_VARIANT_ARRAY, json_dispatch_address, 0, JSON_MANDATORY }, {} }; static uint64_t query_flag( const char *name, const int value, uint64_t flag) { int r; r = getenv_bool_secure(name); if (r >= 0) return r == value ? flag : 0; if (r != -ENXIO) log_debug_errno(r, "Failed to parse $%s, ignoring.", name); return 0; } static uint64_t query_flags(void) { /* Allow callers to turn off validation, synthetization, caching, etc., when we resolve via * nss-resolve. */ return query_flag("SYSTEMD_NSS_RESOLVE_VALIDATE", 0, SD_RESOLVED_NO_VALIDATE) | query_flag("SYSTEMD_NSS_RESOLVE_SYNTHESIZE", 0, SD_RESOLVED_NO_SYNTHESIZE) | query_flag("SYSTEMD_NSS_RESOLVE_CACHE", 0, SD_RESOLVED_NO_CACHE) | query_flag("SYSTEMD_NSS_RESOLVE_ZONE", 0, SD_RESOLVED_NO_ZONE) | query_flag("SYSTEMD_NSS_RESOLVE_TRUST_ANCHOR", 0, SD_RESOLVED_NO_TRUST_ANCHOR) | query_flag("SYSTEMD_NSS_RESOLVE_NETWORK", 0, SD_RESOLVED_NO_NETWORK); } enum nss_status _nss_resolve_gethostbyname4_r( const char *name, struct gaih_addrtuple **pat, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp) { _cleanup_(varlink_unrefp) Varlink *link = NULL; _cleanup_(json_variant_unrefp) JsonVariant *cparams = NULL; _cleanup_(resolve_hostname_reply_destroy) ResolveHostnameReply p = {}; JsonVariant *rparams, *entry; int r; PROTECT_ERRNO; NSS_ENTRYPOINT_BEGIN; assert(name); assert(pat); assert(buffer); assert(errnop); assert(h_errnop); r = connect_to_resolved(&link); if (r < 0) goto fail; r = json_build(&cparams, JSON_BUILD_OBJECT( JSON_BUILD_PAIR("name", JSON_BUILD_STRING(name)), JSON_BUILD_PAIR("flags", JSON_BUILD_UNSIGNED(query_flags())))); if (r < 0) goto fail; /* Return NSS_STATUS_UNAVAIL when communication with systemd-resolved fails, allowing falling * back to other nss modules. Treat all other error conditions as NOTFOUND. This includes * DNSSEC errors and suchlike. (We don't use UNAVAIL in this case so that the nsswitch.conf * configuration can distinguish such executed but negative replies from complete failure to * talk to resolved). */ const char *error_id; r = varlink_call(link, "io.systemd.Resolve.ResolveHostname", cparams, &rparams, &error_id, NULL); if (r < 0) goto fail; if (!isempty(error_id)) { if (error_shall_try_again(error_id)) goto try_again; if (error_shall_fallback(error_id)) goto fail; goto not_found; } r = json_dispatch(rparams, resolve_hostname_reply_dispatch_table, NULL, json_dispatch_flags, &p); if (r < 0) goto fail; if (json_variant_is_blank_object(p.addresses)) goto not_found; size_t n_addresses = 0; JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) { AddressParameters q = {}; r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q); if (r < 0) goto fail; if (!IN_SET(q.family, AF_INET, AF_INET6)) continue; if (q.address_size != FAMILY_ADDRESS_SIZE(q.family)) { r = -EINVAL; goto fail; } n_addresses++; } const char *canonical = p.name ?: name; size_t l = strlen(canonical); size_t idx, ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * n_addresses; if (buflen < ms) { UNPROTECT_ERRNO; *errnop = ERANGE; *h_errnop = NETDB_INTERNAL; return NSS_STATUS_TRYAGAIN; } /* First, append name */ char *r_name = buffer; memcpy(r_name, canonical, l + 1); idx = ALIGN(l + 1); /* Second, append addresses */ struct gaih_addrtuple *r_tuple = NULL, *r_tuple_first = (struct gaih_addrtuple*) (buffer + idx); JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) { AddressParameters q = {}; r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q); if (r < 0) goto fail; if (!IN_SET(q.family, AF_INET, AF_INET6)) continue; r_tuple = (struct gaih_addrtuple*) (buffer + idx); r_tuple->next = (struct gaih_addrtuple*) ((char*) r_tuple + ALIGN(sizeof(struct gaih_addrtuple))); r_tuple->name = r_name; r_tuple->family = q.family; r_tuple->scopeid = ifindex_to_scopeid(q.family, &q.address, q.ifindex); memcpy(r_tuple->addr, &q.address, q.address_size); idx += ALIGN(sizeof(struct gaih_addrtuple)); } assert(r_tuple); /* We had at least one address, so r_tuple must be set */ r_tuple->next = NULL; /* Override last next pointer */ assert(idx == ms); if (*pat) **pat = *r_tuple_first; else *pat = r_tuple_first; 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; fail: UNPROTECT_ERRNO; *errnop = -r; *h_errnop = NO_RECOVERY; return NSS_STATUS_UNAVAIL; not_found: *h_errnop = HOST_NOT_FOUND; return NSS_STATUS_NOTFOUND; try_again: UNPROTECT_ERRNO; *errnop = -r; *h_errnop = TRY_AGAIN; return NSS_STATUS_TRYAGAIN; } enum nss_status _nss_resolve_gethostbyname3_r( const char *name, int af, struct hostent *result, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp, char **canonp) { _cleanup_(varlink_unrefp) Varlink *link = NULL; _cleanup_(json_variant_unrefp) JsonVariant *cparams = NULL; _cleanup_(resolve_hostname_reply_destroy) ResolveHostnameReply p = {}; JsonVariant *rparams, *entry; int r; PROTECT_ERRNO; NSS_ENTRYPOINT_BEGIN; assert(name); assert(result); assert(buffer); assert(errnop); assert(h_errnop); if (af == AF_UNSPEC) af = AF_INET; if (!IN_SET(af, AF_INET, AF_INET6)) { r = -EAFNOSUPPORT; goto fail; } r = connect_to_resolved(&link); if (r < 0) goto fail; r = json_build(&cparams, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("name", JSON_BUILD_STRING(name)), JSON_BUILD_PAIR("family", JSON_BUILD_INTEGER(af)), JSON_BUILD_PAIR("flags", JSON_BUILD_UNSIGNED(query_flags())))); if (r < 0) goto fail; const char *error_id; r = varlink_call(link, "io.systemd.Resolve.ResolveHostname", cparams, &rparams, &error_id, NULL); if (r < 0) goto fail; if (!isempty(error_id)) { if (error_shall_try_again(error_id)) goto try_again; if (error_shall_fallback(error_id)) goto fail; goto not_found; } r = json_dispatch(rparams, resolve_hostname_reply_dispatch_table, NULL, json_dispatch_flags, &p); if (r < 0) goto fail; if (json_variant_is_blank_object(p.addresses)) goto not_found; size_t n_addresses = 0; JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) { AddressParameters q = {}; r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q); if (r < 0) goto fail; if (!IN_SET(q.family, AF_INET, AF_INET6)) continue; if (q.address_size != FAMILY_ADDRESS_SIZE(q.family)) { r = -EINVAL; goto fail; } n_addresses++; } const char *canonical = p.name ?: name; size_t alen = FAMILY_ADDRESS_SIZE(af); size_t l = strlen(canonical); size_t idx, ms = ALIGN(l + 1) + n_addresses * ALIGN(alen) + (n_addresses + 2) * sizeof(char*); if (buflen < ms) { UNPROTECT_ERRNO; *errnop = ERANGE; *h_errnop = NETDB_INTERNAL; return NSS_STATUS_TRYAGAIN; } /* First, append name */ char *r_name = buffer; memcpy(r_name, canonical, l+1); idx = ALIGN(l+1); /* Second, create empty aliases array */ char *r_aliases = buffer + idx; ((char**) r_aliases)[0] = NULL; idx += sizeof(char*); /* Third, append addresses */ char *r_addr = buffer + idx; size_t i = 0; JSON_VARIANT_ARRAY_FOREACH(entry, p.addresses) { AddressParameters q = {}; r = json_dispatch(entry, address_parameters_dispatch_table, NULL, json_dispatch_flags, &q); if (r < 0) goto fail; if (q.family != af) continue; if (q.address_size != alen) { r = -EINVAL; goto fail; } memcpy(r_addr + i*ALIGN(alen), &q.address, alen); i++; } assert(i == n_addresses); idx += n_addresses * ALIGN(alen); /* Fourth, append address pointer array */ char *r_addr_list = buffer + idx; for (i = 0; i < n_addresses; i++) ((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen); ((char**) r_addr_list)[i] = NULL; idx += (n_addresses + 1) * sizeof(char*); 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; fail: UNPROTECT_ERRNO; *errnop = -r; *h_errnop = NO_RECOVERY; return NSS_STATUS_UNAVAIL; not_found: *h_errnop = HOST_NOT_FOUND; return NSS_STATUS_NOTFOUND; try_again: UNPROTECT_ERRNO; *errnop = -r; *h_errnop = TRY_AGAIN; return NSS_STATUS_TRYAGAIN; } typedef struct ResolveAddressReply { JsonVariant *names; uint64_t flags; } ResolveAddressReply; static void resolve_address_reply_destroy(ResolveAddressReply *p) { assert(p); json_variant_unref(p->names); } static const JsonDispatch resolve_address_reply_dispatch_table[] = { { "names", JSON_VARIANT_ARRAY, json_dispatch_variant, offsetof(ResolveAddressReply, names), JSON_MANDATORY }, { "flags", JSON_VARIANT_UNSIGNED, json_dispatch_uint64, offsetof(ResolveAddressReply, flags), 0 }, {} }; typedef struct NameParameters { int ifindex; char *name; } NameParameters; static void name_parameters_destroy(NameParameters *p) { assert(p); free(p->name); } static const JsonDispatch name_parameters_dispatch_table[] = { { "ifindex", JSON_VARIANT_INTEGER, json_dispatch_ifindex, offsetof(NameParameters, ifindex), 0 }, { "name", JSON_VARIANT_STRING, json_dispatch_string, offsetof(NameParameters, name), JSON_MANDATORY }, {} }; enum nss_status _nss_resolve_gethostbyaddr2_r( const void* addr, socklen_t len, int af, struct hostent *result, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp) { _cleanup_(varlink_unrefp) Varlink *link = NULL; _cleanup_(json_variant_unrefp) JsonVariant *cparams = NULL; _cleanup_(resolve_address_reply_destroy) ResolveAddressReply p = {}; JsonVariant *rparams, *entry; int r; PROTECT_ERRNO; NSS_ENTRYPOINT_BEGIN; assert(addr); assert(result); 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)) { r = -EINVAL; goto fail; } r = connect_to_resolved(&link); if (r < 0) goto fail; r = json_build(&cparams, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("address", JSON_BUILD_BYTE_ARRAY(addr, len)), JSON_BUILD_PAIR("family", JSON_BUILD_INTEGER(af)), JSON_BUILD_PAIR("flags", JSON_BUILD_UNSIGNED(query_flags())))); if (r < 0) goto fail; const char* error_id; r = varlink_call(link, "io.systemd.Resolve.ResolveAddress", cparams, &rparams, &error_id, NULL); if (r < 0) goto fail; if (!isempty(error_id)) { if (error_shall_try_again(error_id)) goto try_again; if (error_shall_fallback(error_id)) goto fail; goto not_found; } r = json_dispatch(rparams, resolve_address_reply_dispatch_table, NULL, json_dispatch_flags, &p); if (r < 0) goto fail; if (json_variant_is_blank_object(p.names)) goto not_found; size_t ms = 0, idx; JSON_VARIANT_ARRAY_FOREACH(entry, p.names) { _cleanup_(name_parameters_destroy) NameParameters q = {}; r = json_dispatch(entry, name_parameters_dispatch_table, NULL, json_dispatch_flags, &q); if (r < 0) goto fail; ms += ALIGN(strlen(q.name) + 1); } size_t n_names = json_variant_elements(p.names); ms += ALIGN(len) + /* the address */ 2 * sizeof(char*) + /* pointer to the address, plus trailing NULL */ n_names * sizeof(char*); /* pointers to aliases, plus trailing NULL */ if (buflen < ms) { UNPROTECT_ERRNO; *errnop = ERANGE; *h_errnop = NETDB_INTERNAL; return NSS_STATUS_TRYAGAIN; } /* First, place address */ char *r_addr = buffer; memcpy(r_addr, addr, len); idx = ALIGN(len); /* Second, place address list */ char *r_addr_list = buffer + idx; ((char**) r_addr_list)[0] = r_addr; ((char**) r_addr_list)[1] = NULL; idx += sizeof(char*) * 2; /* Third, reserve space for the aliases array, plus trailing NULL */ char *r_aliases = buffer + idx; idx += sizeof(char*) * n_names; /* Fourth, place aliases */ char *r_name = buffer + idx; size_t i = 0; JSON_VARIANT_ARRAY_FOREACH(entry, p.names) { _cleanup_(name_parameters_destroy) NameParameters q = {}; r = json_dispatch(entry, name_parameters_dispatch_table, NULL, json_dispatch_flags, &q); if (r < 0) goto fail; size_t l = strlen(q.name); char *z = buffer + idx; memcpy(z, q.name, l + 1); if (i > 0) ((char**) r_aliases)[i - 1] = z; i++; idx += ALIGN(l + 1); } ((char**) r_aliases)[n_names - 1] = NULL; assert(idx == ms); result->h_name = r_name; result->h_aliases = (char**) r_aliases; result->h_addrtype = af; result->h_length = len; result->h_addr_list = (char**) r_addr_list; 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; fail: UNPROTECT_ERRNO; *errnop = -r; *h_errnop = NO_RECOVERY; return NSS_STATUS_UNAVAIL; not_found: *h_errnop = HOST_NOT_FOUND; return NSS_STATUS_NOTFOUND; try_again: UNPROTECT_ERRNO; *errnop = -r; *h_errnop = TRY_AGAIN; return NSS_STATUS_TRYAGAIN; } NSS_GETHOSTBYNAME_FALLBACKS(resolve); NSS_GETHOSTBYADDR_FALLBACKS(resolve);