/* $OpenBSD: x509_verify.c,v 1.59 2022/06/28 16:05:42 beck Exp $ */ /* * Copyright (c) 2020-2021 Bob Beck * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* x509_verify - inspired by golang's crypto/x509.Verify */ #include #include #include #include #include #include #include #include #include "x509_internal.h" #include "x509_issuer_cache.h" static int x509_verify_cert_valid(struct x509_verify_ctx *ctx, X509 *cert, struct x509_verify_chain *current_chain); static int x509_verify_cert_hostname(struct x509_verify_ctx *ctx, X509 *cert, char *name); static void x509_verify_build_chains(struct x509_verify_ctx *ctx, X509 *cert, struct x509_verify_chain *current_chain, int full_chain, char *name); static int x509_verify_cert_error(struct x509_verify_ctx *ctx, X509 *cert, size_t depth, int error, int ok); static void x509_verify_chain_free(struct x509_verify_chain *chain); /* * Parse an asn1 to a representable time_t as per RFC 5280 rules. * Returns -1 if that can't be done for any reason. */ time_t x509_verify_asn1_time_to_time_t(const ASN1_TIME *atime, int notAfter) { struct tm tm = { 0 }; int type; type = ASN1_time_parse(atime->data, atime->length, &tm, atime->type); if (type == -1) return -1; /* RFC 5280 section 4.1.2.5 */ if (tm.tm_year < 150 && type != V_ASN1_UTCTIME) return -1; if (tm.tm_year >= 150 && type != V_ASN1_GENERALIZEDTIME) return -1; if (notAfter) { /* * If we are a completely broken operating system with a * 32 bit time_t, and we have been told this is a notAfter * date, limit the date to a 32 bit representable value. */ if (!ASN1_time_tm_clamp_notafter(&tm)) return -1; } /* * Defensively fail if the time string is not representable as * a time_t. A time_t must be sane if you care about times after * Jan 19 2038. */ return timegm(&tm); } /* * Cache certificate hash, and values parsed out of an X509. * called from cache_extensions() */ void x509_verify_cert_info_populate(X509 *cert) { /* * Parse and save the cert times, or remember that they * are unacceptable/unparsable. */ cert->not_before = x509_verify_asn1_time_to_time_t(X509_get_notBefore(cert), 0); cert->not_after = x509_verify_asn1_time_to_time_t(X509_get_notAfter(cert), 1); } struct x509_verify_chain * x509_verify_chain_new(void) { struct x509_verify_chain *chain; if ((chain = calloc(1, sizeof(*chain))) == NULL) goto err; if ((chain->certs = sk_X509_new_null()) == NULL) goto err; if ((chain->cert_errors = calloc(X509_VERIFY_MAX_CHAIN_CERTS, sizeof(int))) == NULL) goto err; if ((chain->names = x509_constraints_names_new(X509_VERIFY_MAX_CHAIN_NAMES)) == NULL) goto err; return chain; err: x509_verify_chain_free(chain); return NULL; } static void x509_verify_chain_clear(struct x509_verify_chain *chain) { sk_X509_pop_free(chain->certs, X509_free); chain->certs = NULL; free(chain->cert_errors); chain->cert_errors = NULL; x509_constraints_names_free(chain->names); chain->names = NULL; } static void x509_verify_chain_free(struct x509_verify_chain *chain) { if (chain == NULL) return; x509_verify_chain_clear(chain); free(chain); } static struct x509_verify_chain * x509_verify_chain_dup(struct x509_verify_chain *chain) { struct x509_verify_chain *new_chain; if ((new_chain = calloc(1, sizeof(*chain))) == NULL) goto err; if ((new_chain->certs = X509_chain_up_ref(chain->certs)) == NULL) goto err; if ((new_chain->cert_errors = calloc(X509_VERIFY_MAX_CHAIN_CERTS, sizeof(int))) == NULL) goto err; memcpy(new_chain->cert_errors, chain->cert_errors, X509_VERIFY_MAX_CHAIN_CERTS * sizeof(int)); if ((new_chain->names = x509_constraints_names_dup(chain->names)) == NULL) goto err; return(new_chain); err: x509_verify_chain_free(new_chain); return NULL; } static int x509_verify_chain_append(struct x509_verify_chain *chain, X509 *cert, int *error) { int verify_err = X509_V_ERR_UNSPECIFIED; size_t idx; if (!x509_constraints_extract_names(chain->names, cert, sk_X509_num(chain->certs) == 0, &verify_err)) { *error = verify_err; return 0; } X509_up_ref(cert); if (!sk_X509_push(chain->certs, cert)) { X509_free(cert); *error = X509_V_ERR_OUT_OF_MEM; return 0; } idx = sk_X509_num(chain->certs) - 1; chain->cert_errors[idx] = *error; /* * We've just added the issuer for the previous certificate, * clear its error if appropriate. */ if (idx > 1 && chain->cert_errors[idx - 1] == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY) chain->cert_errors[idx - 1] = X509_V_OK; return 1; } static X509 * x509_verify_chain_last(struct x509_verify_chain *chain) { int last; if (chain->certs == NULL) return NULL; if ((last = sk_X509_num(chain->certs) - 1) < 0) return NULL; return sk_X509_value(chain->certs, last); } X509 * x509_verify_chain_leaf(struct x509_verify_chain *chain) { if (chain->certs == NULL) return NULL; return sk_X509_value(chain->certs, 0); } static void x509_verify_ctx_reset(struct x509_verify_ctx *ctx) { size_t i; for (i = 0; i < ctx->chains_count; i++) x509_verify_chain_free(ctx->chains[i]); sk_X509_pop_free(ctx->saved_error_chain, X509_free); ctx->saved_error = 0; ctx->saved_error_depth = 0; ctx->error = 0; ctx->error_depth = 0; ctx->chains_count = 0; ctx->sig_checks = 0; ctx->check_time = NULL; } static void x509_verify_ctx_clear(struct x509_verify_ctx *ctx) { x509_verify_ctx_reset(ctx); sk_X509_pop_free(ctx->intermediates, X509_free); free(ctx->chains); } static int x509_verify_cert_cache_extensions(X509 *cert) { if (!(cert->ex_flags & EXFLAG_SET)) { CRYPTO_w_lock(CRYPTO_LOCK_X509); x509v3_cache_extensions(cert); CRYPTO_w_unlock(CRYPTO_LOCK_X509); } if (cert->ex_flags & EXFLAG_INVALID) return 0; return (cert->ex_flags & EXFLAG_SET); } static int x509_verify_cert_self_signed(X509 *cert) { return (cert->ex_flags & EXFLAG_SS) ? 1 : 0; } /* XXX beck - clean up this mess of is_root */ static int x509_verify_check_chain_end(X509 *cert, int full_chain) { if (full_chain) return x509_verify_cert_self_signed(cert); return 1; } static int x509_verify_check_legacy_chain_end(struct x509_verify_ctx *ctx, X509 *cert, int full_chain) { if (X509_check_trust(cert, ctx->xsc->param->trust, 0) != X509_TRUST_TRUSTED) return 0; return x509_verify_check_chain_end(cert, full_chain); } static int x509_verify_ctx_cert_is_root(struct x509_verify_ctx *ctx, X509 *cert, int full_chain) { X509 *match = NULL; int i; if (!x509_verify_cert_cache_extensions(cert)) return 0; /* Check by lookup if we have a legacy xsc */ if (ctx->xsc != NULL) { if ((match = x509_vfy_lookup_cert_match(ctx->xsc, cert)) != NULL) { X509_free(match); return x509_verify_check_legacy_chain_end(ctx, cert, full_chain); } } else { /* Check the provided roots */ for (i = 0; i < sk_X509_num(ctx->roots); i++) { if (X509_cmp(sk_X509_value(ctx->roots, i), cert) == 0) return x509_verify_check_chain_end(cert, full_chain); } } return 0; } static int x509_verify_ctx_set_xsc_chain(struct x509_verify_ctx *ctx, struct x509_verify_chain *chain, int set_error, int is_trusted) { size_t num_untrusted; int i; if (ctx->xsc == NULL) return 1; /* * XXX num_untrusted is the number of untrusted certs at the * bottom of the chain. This works now since we stop at the first * trusted cert. This will need fixing once we allow more than one * trusted certificate. */ num_untrusted = sk_X509_num(chain->certs); if (is_trusted && num_untrusted > 0) num_untrusted--; ctx->xsc->num_untrusted = num_untrusted; sk_X509_pop_free(ctx->xsc->chain, X509_free); ctx->xsc->chain = X509_chain_up_ref(chain->certs); if (ctx->xsc->chain == NULL) return x509_verify_cert_error(ctx, NULL, 0, X509_V_ERR_OUT_OF_MEM, 0); if (set_error) { ctx->xsc->error = X509_V_OK; ctx->xsc->error_depth = 0; for (i = 0; i < sk_X509_num(chain->certs); i++) { if (chain->cert_errors[i] != X509_V_OK) { ctx->xsc->error = chain->cert_errors[i]; ctx->xsc->error_depth = i; break; } } } return 1; } /* * Save the error state and unvalidated chain off of the xsc for * later. */ static int x509_verify_ctx_save_xsc_error(struct x509_verify_ctx *ctx) { if (ctx->xsc != NULL && ctx->xsc->chain != NULL) { sk_X509_pop_free(ctx->saved_error_chain, X509_free); ctx->saved_error_chain = X509_chain_up_ref(ctx->xsc->chain); if (ctx->saved_error_chain == NULL) return x509_verify_cert_error(ctx, NULL, 0, X509_V_ERR_OUT_OF_MEM, 0); ctx->saved_error = ctx->xsc->error; ctx->saved_error_depth = ctx->xsc->error_depth; } return 1; } /* * Restore the saved error state and unvalidated chain to the xsc * if we do not have a validated chain. */ static int x509_verify_ctx_restore_xsc_error(struct x509_verify_ctx *ctx) { if (ctx->xsc != NULL && ctx->chains_count == 0 && ctx->saved_error_chain != NULL) { sk_X509_pop_free(ctx->xsc->chain, X509_free); ctx->xsc->chain = X509_chain_up_ref(ctx->saved_error_chain); if (ctx->xsc->chain == NULL) return x509_verify_cert_error(ctx, NULL, 0, X509_V_ERR_OUT_OF_MEM, 0); ctx->xsc->error = ctx->saved_error; ctx->xsc->error_depth = ctx->saved_error_depth; } return 1; } /* Perform legacy style validation of a chain */ static int x509_verify_ctx_validate_legacy_chain(struct x509_verify_ctx *ctx, struct x509_verify_chain *chain, size_t depth) { int ret = 0, trust; if (ctx->xsc == NULL) return 1; /* * If we have a legacy xsc, choose a validated chain, and * apply the extensions, revocation, and policy checks just * like the legacy code did. We do this here instead of as * building the chains to more easily support the callback and * the bewildering array of VERIFY_PARAM knobs that are there * for the fiddling. */ /* These may be set in one of the following calls. */ ctx->xsc->error = X509_V_OK; ctx->xsc->error_depth = 0; if (!x509_verify_ctx_set_xsc_chain(ctx, chain, 0, 1)) goto err; /* * Call the legacy code to walk the chain and check trust * in the legacy way to handle partial chains and get the * callback fired correctly. */ trust = x509_vfy_check_trust(ctx->xsc); if (trust == X509_TRUST_REJECTED) goto err; /* callback was called in x509_vfy_check_trust */ if (trust != X509_TRUST_TRUSTED) { /* NOTREACHED */ goto err; /* should not happen if we get in here - abort? */ } /* * XXX currently this duplicates some work done in chain * build, but we keep it here until we have feature parity */ if (!x509_vfy_check_chain_extensions(ctx->xsc)) goto err; #ifndef OPENSSL_NO_RFC3779 if (!X509v3_asid_validate_path(ctx->xsc)) goto err; if (!X509v3_addr_validate_path(ctx->xsc)) goto err; #endif if (!x509_vfy_check_security_level(ctx->xsc)) goto err; if (!x509_constraints_chain(ctx->xsc->chain, &ctx->xsc->error, &ctx->xsc->error_depth)) { X509 *cert = sk_X509_value(ctx->xsc->chain, depth); if (!x509_verify_cert_error(ctx, cert, ctx->xsc->error_depth, ctx->xsc->error, 0)) goto err; } if (!x509_vfy_check_revocation(ctx->xsc)) goto err; if (!x509_vfy_check_policy(ctx->xsc)) goto err; ret = 1; err: /* * The above checks may have set ctx->xsc->error and * ctx->xsc->error_depth - save these for later on. */ if (ctx->xsc->error != X509_V_OK) { if (ctx->xsc->error_depth < 0 || ctx->xsc->error_depth >= X509_VERIFY_MAX_CHAIN_CERTS) return 0; chain->cert_errors[ctx->xsc->error_depth] = ctx->xsc->error; ctx->error_depth = ctx->xsc->error_depth; } return ret; } /* Add a validated chain to our list of valid chains */ static int x509_verify_ctx_add_chain(struct x509_verify_ctx *ctx, struct x509_verify_chain *chain, char *name) { size_t depth; X509 *last = x509_verify_chain_last(chain); X509 *leaf = x509_verify_chain_leaf(chain); depth = sk_X509_num(chain->certs); if (depth > 0) depth--; if (ctx->chains_count >= ctx->max_chains) return x509_verify_cert_error(ctx, last, depth, X509_V_ERR_CERT_CHAIN_TOO_LONG, 0); /* Clear a get issuer failure for a root certificate. */ if (chain->cert_errors[depth] == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY) chain->cert_errors[depth] = X509_V_OK; if (!x509_verify_ctx_validate_legacy_chain(ctx, chain, depth)) return 0; /* * In the non-legacy code, extensions and purpose are dealt * with as the chain is built. * * The non-legacy api returns multiple chains but does not do * any revocation checking (it must be done by the caller on * any chain they wish to use) */ if ((ctx->chains[ctx->chains_count] = x509_verify_chain_dup(chain)) == NULL) { return x509_verify_cert_error(ctx, last, depth, X509_V_ERR_OUT_OF_MEM, 0); } if (!x509_verify_cert_valid(ctx, leaf, NULL)) return 0; if (!x509_verify_cert_hostname(ctx, leaf, name)) return 0; ctx->chains_count++; ctx->error = X509_V_OK; ctx->error_depth = depth; return 1; } static int x509_verify_potential_parent(struct x509_verify_ctx *ctx, X509 *parent, X509 *child) { if (!x509_verify_cert_cache_extensions(parent)) return 0; if (ctx->xsc != NULL) return (ctx->xsc->check_issued(ctx->xsc, child, parent)); /* XXX key usage */ return X509_check_issued(child, parent) != X509_V_OK; } static int x509_verify_parent_signature(X509 *parent, X509 *child, int *error) { EVP_PKEY *pkey; int cached; int ret = 0; /* Use cached value if we have it */ if ((cached = x509_issuer_cache_find(parent->hash, child->hash)) >= 0) return cached; /* Check signature. Did parent sign child? */ if ((pkey = X509_get_pubkey(parent)) == NULL) { *error = X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY; return 0; } if (X509_verify(child, pkey) <= 0) *error = X509_V_ERR_CERT_SIGNATURE_FAILURE; else ret = 1; /* Add result to cache */ x509_issuer_cache_add(parent->hash, child->hash, ret); EVP_PKEY_free(pkey); return ret; } static int x509_verify_consider_candidate(struct x509_verify_ctx *ctx, X509 *cert, int is_root_cert, X509 *candidate, struct x509_verify_chain *current_chain, int full_chain, char *name) { int depth = sk_X509_num(current_chain->certs); struct x509_verify_chain *new_chain; int i; /* Fail if the certificate is already in the chain */ for (i = 0; i < sk_X509_num(current_chain->certs); i++) { if (X509_cmp(sk_X509_value(current_chain->certs, i), candidate) == 0) return 0; } if (ctx->sig_checks++ > X509_VERIFY_MAX_SIGCHECKS) { /* don't allow callback to override safety check */ (void) x509_verify_cert_error(ctx, candidate, depth, X509_V_ERR_CERT_CHAIN_TOO_LONG, 0); return 0; } if (!x509_verify_parent_signature(candidate, cert, &ctx->error)) { if (!x509_verify_cert_error(ctx, candidate, depth, ctx->error, 0)) return 0; } if (!x509_verify_cert_valid(ctx, candidate, current_chain)) return 0; /* candidate is good, add it to a copy of the current chain */ if ((new_chain = x509_verify_chain_dup(current_chain)) == NULL) { x509_verify_cert_error(ctx, candidate, depth, X509_V_ERR_OUT_OF_MEM, 0); return 0; } if (!x509_verify_chain_append(new_chain, candidate, &ctx->error)) { x509_verify_cert_error(ctx, candidate, depth, ctx->error, 0); x509_verify_chain_free(new_chain); return 0; } /* * If candidate is a trusted root, we have a validated chain, * so we save it. Otherwise, recurse until we find a root or * give up. */ if (is_root_cert) { if (!x509_verify_ctx_set_xsc_chain(ctx, new_chain, 0, 1)) { x509_verify_chain_free(new_chain); return 0; } if (!x509_verify_ctx_add_chain(ctx, new_chain, name)) { x509_verify_chain_free(new_chain); return 0; } goto done; } x509_verify_build_chains(ctx, candidate, new_chain, full_chain, name); done: x509_verify_chain_free(new_chain); return 1; } static int x509_verify_cert_error(struct x509_verify_ctx *ctx, X509 *cert, size_t depth, int error, int ok) { ctx->error = error; ctx->error_depth = depth; if (ctx->xsc != NULL) { ctx->xsc->error = error; ctx->xsc->error_depth = depth; ctx->xsc->current_cert = cert; return ctx->xsc->verify_cb(ok, ctx->xsc); } return ok; } static void x509_verify_build_chains(struct x509_verify_ctx *ctx, X509 *cert, struct x509_verify_chain *current_chain, int full_chain, char *name) { X509 *candidate; int i, depth, count, ret, is_root; /* * If we are finding chains with an xsc, just stop after we have * one chain, there's no point in finding more, it just exercises * the potentially buggy callback processing in the calling software. */ if (ctx->xsc != NULL && ctx->chains_count > 0) return; depth = sk_X509_num(current_chain->certs); if (depth > 0) depth--; if (depth >= ctx->max_depth && !x509_verify_cert_error(ctx, cert, depth, X509_V_ERR_CERT_CHAIN_TOO_LONG, 0)) return; count = ctx->chains_count; ctx->error = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY; ctx->error_depth = depth; if (ctx->saved_error != 0) ctx->error = ctx->saved_error; if (ctx->saved_error_depth != 0) ctx->error_depth = ctx->saved_error_depth; if (ctx->xsc != NULL) { /* * Long ago experiments at Muppet labs resulted in a * situation where software not only sees these errors * but forced developers to expect them in certain cases. * so we must mimic this awfulness for the legacy case. */ if (cert->ex_flags & EXFLAG_SS) ctx->error = (depth == 0) ? X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN; } /* Check for legacy mode roots */ if (ctx->xsc != NULL) { if ((ret = ctx->xsc->get_issuer(&candidate, ctx->xsc, cert)) < 0) { x509_verify_cert_error(ctx, cert, depth, X509_V_ERR_STORE_LOOKUP, 0); return; } if (ret > 0) { if (x509_verify_potential_parent(ctx, candidate, cert)) { is_root = x509_verify_check_legacy_chain_end( ctx, candidate, full_chain); x509_verify_consider_candidate(ctx, cert, is_root, candidate, current_chain, full_chain, name); } X509_free(candidate); } } else { /* Check to see if we have a trusted root issuer. */ for (i = 0; i < sk_X509_num(ctx->roots); i++) { candidate = sk_X509_value(ctx->roots, i); if (x509_verify_potential_parent(ctx, candidate, cert)) { is_root = x509_verify_check_chain_end(candidate, full_chain); x509_verify_consider_candidate(ctx, cert, is_root, candidate, current_chain, full_chain, name); } } } /* Check intermediates after checking roots */ if (ctx->intermediates != NULL) { for (i = 0; i < sk_X509_num(ctx->intermediates); i++) { candidate = sk_X509_value(ctx->intermediates, i); if (x509_verify_potential_parent(ctx, candidate, cert)) { x509_verify_consider_candidate(ctx, cert, 0, candidate, current_chain, full_chain, name); } } } if (ctx->chains_count > count) { if (ctx->xsc != NULL) { ctx->xsc->error = X509_V_OK; ctx->xsc->error_depth = depth; ctx->xsc->current_cert = cert; } } else if (ctx->error_depth == depth) { if (!x509_verify_ctx_set_xsc_chain(ctx, current_chain, 0, 0)) return; } } static int x509_verify_cert_hostname(struct x509_verify_ctx *ctx, X509 *cert, char *name) { char *candidate; size_t len; if (name == NULL) { if (ctx->xsc != NULL) { int ret; if ((ret = x509_vfy_check_id(ctx->xsc)) == 0) ctx->error = ctx->xsc->error; return ret; } return 1; } if ((candidate = strdup(name)) == NULL) { ctx->error = X509_V_ERR_OUT_OF_MEM; goto err; } if ((len = strlen(candidate)) < 1) { ctx->error = X509_V_ERR_UNSPECIFIED; /* XXX */ goto err; } /* IP addresses may be written in [ ]. */ if (candidate[0] == '[' && candidate[len - 1] == ']') { candidate[len - 1] = '\0'; if (X509_check_ip_asc(cert, candidate + 1, 0) <= 0) { ctx->error = X509_V_ERR_IP_ADDRESS_MISMATCH; goto err; } } else { int flags = 0; if (ctx->xsc == NULL) flags = X509_CHECK_FLAG_NEVER_CHECK_SUBJECT; if (X509_check_host(cert, candidate, len, flags, NULL) <= 0) { ctx->error = X509_V_ERR_HOSTNAME_MISMATCH; goto err; } } free(candidate); return 1; err: free(candidate); return x509_verify_cert_error(ctx, cert, 0, ctx->error, 0); } static int x509_verify_set_check_time(struct x509_verify_ctx *ctx) { if (ctx->xsc != NULL) { if (ctx->xsc->param->flags & X509_V_FLAG_USE_CHECK_TIME) { ctx->check_time = &ctx->xsc->param->check_time; return 1; } if (ctx->xsc->param->flags & X509_V_FLAG_NO_CHECK_TIME) return 0; } ctx->check_time = NULL; return 1; } static int x509_verify_cert_times(X509 *cert, time_t *cmp_time, int *error) { time_t when; if (cmp_time == NULL) when = time(NULL); else when = *cmp_time; if (cert->not_before == -1) { *error = X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD; return 0; } if (when < cert->not_before) { *error = X509_V_ERR_CERT_NOT_YET_VALID; return 0; } if (cert->not_after == -1) { *error = X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD; return 0; } if (when > cert->not_after) { *error = X509_V_ERR_CERT_HAS_EXPIRED; return 0; } return 1; } static int x509_verify_validate_constraints(X509 *cert, struct x509_verify_chain *current_chain, int *error) { struct x509_constraints_names *excluded = NULL; struct x509_constraints_names *permitted = NULL; int err = X509_V_ERR_UNSPECIFIED; if (current_chain == NULL) return 1; if (cert->nc != NULL) { if ((permitted = x509_constraints_names_new( X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { err = X509_V_ERR_OUT_OF_MEM; goto err; } if ((excluded = x509_constraints_names_new( X509_VERIFY_MAX_CHAIN_CONSTRAINTS)) == NULL) { err = X509_V_ERR_OUT_OF_MEM; goto err; } if (!x509_constraints_extract_constraints(cert, permitted, excluded, &err)) goto err; if (!x509_constraints_check(current_chain->names, permitted, excluded, &err)) goto err; x509_constraints_names_free(excluded); x509_constraints_names_free(permitted); } return 1; err: *error = err; x509_constraints_names_free(excluded); x509_constraints_names_free(permitted); return 0; } static int x509_verify_cert_extensions(struct x509_verify_ctx *ctx, X509 *cert, int need_ca) { if (!x509_verify_cert_cache_extensions(cert)) { ctx->error = X509_V_ERR_UNSPECIFIED; return 0; } if (ctx->xsc != NULL) return 1; /* legacy is checked after chain is built */ if (cert->ex_flags & EXFLAG_CRITICAL) { ctx->error = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION; return 0; } /* No we don't care about v1, netscape, and other ancient silliness */ if (need_ca && (!(cert->ex_flags & EXFLAG_BCONS) && (cert->ex_flags & EXFLAG_CA))) { ctx->error = X509_V_ERR_INVALID_CA; return 0; } if (ctx->purpose > 0 && X509_check_purpose(cert, ctx->purpose, need_ca)) { ctx->error = X509_V_ERR_INVALID_PURPOSE; return 0; } /* XXX support proxy certs later in new api */ if (ctx->xsc == NULL && cert->ex_flags & EXFLAG_PROXY) { ctx->error = X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED; return 0; } return 1; } /* Validate that cert is a possible candidate to append to current_chain */ static int x509_verify_cert_valid(struct x509_verify_ctx *ctx, X509 *cert, struct x509_verify_chain *current_chain) { X509 *issuer_candidate; int should_be_ca = current_chain != NULL; size_t depth = 0; if (current_chain != NULL) depth = sk_X509_num(current_chain->certs); if (!x509_verify_cert_extensions(ctx, cert, should_be_ca)) return 0; if (should_be_ca) { issuer_candidate = x509_verify_chain_last(current_chain); if (issuer_candidate != NULL && !X509_check_issued(issuer_candidate, cert)) if (!x509_verify_cert_error(ctx, cert, depth, X509_V_ERR_SUBJECT_ISSUER_MISMATCH, 0)) return 0; } if (x509_verify_set_check_time(ctx)) { if (!x509_verify_cert_times(cert, ctx->check_time, &ctx->error)) { if (!x509_verify_cert_error(ctx, cert, depth, ctx->error, 0)) return 0; } } if (!x509_verify_validate_constraints(cert, current_chain, &ctx->error) && !x509_verify_cert_error(ctx, cert, depth, ctx->error, 0)) return 0; return 1; } struct x509_verify_ctx * x509_verify_ctx_new_from_xsc(X509_STORE_CTX *xsc) { struct x509_verify_ctx *ctx; size_t max_depth; if (xsc == NULL) return NULL; if ((ctx = x509_verify_ctx_new(NULL)) == NULL) return NULL; ctx->xsc = xsc; if (xsc->untrusted && (ctx->intermediates = X509_chain_up_ref(xsc->untrusted)) == NULL) goto err; max_depth = X509_VERIFY_MAX_CHAIN_CERTS; if (xsc->param->depth > 0 && xsc->param->depth < X509_VERIFY_MAX_CHAIN_CERTS) max_depth = xsc->param->depth; if (!x509_verify_ctx_set_max_depth(ctx, max_depth)) goto err; return ctx; err: x509_verify_ctx_free(ctx); return NULL; } /* Public API */ struct x509_verify_ctx * x509_verify_ctx_new(STACK_OF(X509) *roots) { struct x509_verify_ctx *ctx; if ((ctx = calloc(1, sizeof(struct x509_verify_ctx))) == NULL) return NULL; if (roots != NULL) { if ((ctx->roots = X509_chain_up_ref(roots)) == NULL) goto err; } else { if ((ctx->roots = sk_X509_new_null()) == NULL) goto err; } ctx->max_depth = X509_VERIFY_MAX_CHAIN_CERTS; ctx->max_chains = X509_VERIFY_MAX_CHAINS; ctx->max_sigs = X509_VERIFY_MAX_SIGCHECKS; if ((ctx->chains = calloc(X509_VERIFY_MAX_CHAINS, sizeof(*ctx->chains))) == NULL) goto err; return ctx; err: x509_verify_ctx_free(ctx); return NULL; } void x509_verify_ctx_free(struct x509_verify_ctx *ctx) { if (ctx == NULL) return; sk_X509_pop_free(ctx->roots, X509_free); x509_verify_ctx_clear(ctx); free(ctx); } int x509_verify_ctx_set_max_depth(struct x509_verify_ctx *ctx, size_t max) { if (max < 1 || max > X509_VERIFY_MAX_CHAIN_CERTS) return 0; ctx->max_depth = max; return 1; } int x509_verify_ctx_set_max_chains(struct x509_verify_ctx *ctx, size_t max) { if (max < 1 || max > X509_VERIFY_MAX_CHAINS) return 0; ctx->max_chains = max; return 1; } int x509_verify_ctx_set_max_signatures(struct x509_verify_ctx *ctx, size_t max) { if (max < 1 || max > 100000) return 0; ctx->max_sigs = max; return 1; } int x509_verify_ctx_set_purpose(struct x509_verify_ctx *ctx, int purpose) { if (purpose < X509_PURPOSE_MIN || purpose > X509_PURPOSE_MAX) return 0; ctx->purpose = purpose; return 1; } int x509_verify_ctx_set_intermediates(struct x509_verify_ctx *ctx, STACK_OF(X509) *intermediates) { if ((ctx->intermediates = X509_chain_up_ref(intermediates)) == NULL) return 0; return 1; } const char * x509_verify_ctx_error_string(struct x509_verify_ctx *ctx) { return X509_verify_cert_error_string(ctx->error); } size_t x509_verify_ctx_error_depth(struct x509_verify_ctx *ctx) { return ctx->error_depth; } STACK_OF(X509) * x509_verify_ctx_chain(struct x509_verify_ctx *ctx, size_t i) { if (i >= ctx->chains_count) return NULL; return ctx->chains[i]->certs; } size_t x509_verify(struct x509_verify_ctx *ctx, X509 *leaf, char *name) { struct x509_verify_chain *current_chain; int retry_chain_build, full_chain = 0; if (ctx->roots == NULL || ctx->max_depth == 0) { ctx->error = X509_V_ERR_INVALID_CALL; goto err; } if (ctx->xsc != NULL) { if (leaf != NULL || name != NULL) { ctx->error = X509_V_ERR_INVALID_CALL; goto err; } leaf = ctx->xsc->cert; /* XXX */ full_chain = 1; if (ctx->xsc->param->flags & X509_V_FLAG_PARTIAL_CHAIN) full_chain = 0; /* * XXX * The legacy code expects the top level cert to be * there, even if we didn't find a chain. So put it * there, we will clobber it later if we find a valid * chain. */ if ((ctx->xsc->chain = sk_X509_new_null()) == NULL) { ctx->error = X509_V_ERR_OUT_OF_MEM; goto err; } if (!X509_up_ref(leaf)) { ctx->error = X509_V_ERR_OUT_OF_MEM; goto err; } if (!sk_X509_push(ctx->xsc->chain, leaf)) { X509_free(leaf); ctx->error = X509_V_ERR_OUT_OF_MEM; goto err; } ctx->xsc->error_depth = 0; ctx->xsc->current_cert = leaf; } if ((current_chain = x509_verify_chain_new()) == NULL) { ctx->error = X509_V_ERR_OUT_OF_MEM; goto err; } /* * Add the leaf to the chain and try to build chains from it. * Note that unlike Go's verifier, we have not yet checked * anything about the leaf, This is intentional, so that we * report failures in chain building before we report problems * with the leaf. */ if (!x509_verify_chain_append(current_chain, leaf, &ctx->error)) { x509_verify_chain_free(current_chain); goto err; } do { retry_chain_build = 0; if (x509_verify_ctx_cert_is_root(ctx, leaf, full_chain)) { if (!x509_verify_ctx_add_chain(ctx, current_chain, name)) { x509_verify_chain_free(current_chain); goto err; } } else { x509_verify_build_chains(ctx, leaf, current_chain, full_chain, name); if (full_chain && ctx->chains_count == 0) { /* * Save the error state from the xsc * at this point to put back on the * xsc in case we do not find a chain * that is trusted but not a full * chain to a self signed root. This * is because the unvalidated chain is * used by the autochain batshittery * on failure and will be needed for * that. */ ctx->xsc->error_depth = ctx->error_depth; if (!x509_verify_ctx_save_xsc_error(ctx)) { x509_verify_chain_free(current_chain); goto err; } full_chain = 0; retry_chain_build = 1; } } } while (retry_chain_build); x509_verify_chain_free(current_chain); /* * Do the new verifier style return, where we don't have an xsc * that allows a crazy callback to turn invalid things into valid. */ if (ctx->xsc == NULL) { /* * Safety net: * We could not find a validated chain, and for some reason do not * have an error set. */ if (ctx->chains_count == 0 && ctx->error == X509_V_OK) ctx->error = X509_V_ERR_UNSPECIFIED; /* * If we are not using an xsc, and have no possibility for the * crazy OpenSSL callback API changing the results of * validation steps (because the callback can make validation * proceed in the presence of invalid certs), any chains we * have here are correctly built and verified. */ if (ctx->chains_count > 0) ctx->error = X509_V_OK; return ctx->chains_count; } /* * Otherwise we are doing compatibility with an xsc, which means that we * will have one chain, which might actually be a bogus chain because * the callback told us to ignore errors and proceed to build an invalid * chain. Possible return values from this include returning 1 with an * invalid chain and a value of xsc->error != X509_V_OK (It's tradition * that makes it ok). */ if (ctx->chains_count > 0) { /* * The chain we have using an xsc might not be a verified chain * if the callback perverted things while we built it to ignore * failures and proceed with chain building. We put this chain * and the error associated with it on the xsc. */ if (!x509_verify_ctx_set_xsc_chain(ctx, ctx->chains[0], 1, 1)) goto err; /* * Call the callback for completion up our built * chain. The callback could still tell us to * fail. Since this chain might exist as the result of * callback doing perversions, we could still return * "success" with something other than X509_V_OK set * as the error. */ if (!x509_vfy_callback_indicate_completion(ctx->xsc)) goto err; } else { /* * We did not find a chain. Bring back the failure * case we wanted to the xsc if we saved one. If we * did not we should have just the leaf on the xsc. */ if (!x509_verify_ctx_restore_xsc_error(ctx)) goto err; /* * Safety net, ensure we have an error set in the * failing case. */ if (ctx->xsc->error == X509_V_OK) { if (ctx->error == X509_V_OK) ctx->error = X509_V_ERR_UNSPECIFIED; ctx->xsc->error = ctx->error; } /* * Let the callback override the return value * at depth 0 if it chooses to */ return ctx->xsc->verify_cb(0, ctx->xsc); } /* We only ever find one chain in compat mode with an xsc. */ return 1; err: if (ctx->error == X509_V_OK) ctx->error = X509_V_ERR_UNSPECIFIED; if (ctx->xsc != NULL) { if (ctx->xsc->error == X509_V_OK) ctx->xsc->error = X509_V_ERR_UNSPECIFIED; ctx->error = ctx->xsc->error; } return 0; }