On Sat, Mar 13, 2021 at 09:20:32PM +0100, Tobias Heider wrote: > On Wed, Mar 03, 2021 at 05:36:12PM +0100, Theo Buehler wrote: > > On Thu, Feb 25, 2021 at 09:34:30PM +0100, Tobias Heider wrote: > > > Hi, > > > > > > while testing different x509 validator corner cases i found that a bunch > > > of > > > errors are currently not handled in libcrypto. > > > > > > In particular duplicate or undecodable extensions are ignored. > > > The diff below sets EXFLAG_INVALID whenever X509_get_ext_d2i() returns > > > an error (other than "not found") and later throws X509_V_ERR_UNSPECIFIED > > > if EXFLAG_INVALID is set. > > > > Yes, we want this in some form. Apart from the X509_vfy bit this is a > > subset of the changes in > > > > https://github.com/openssl/openssl/pull/10756 > > > > While I'd be happy to land this in a few smaller pieces, I think we want > > most of those changes. In particular, I think we want to check for > > EXFLAG_INVALID after all calls to x509v3_cache_extensions(). > > Below is an updated diff with checks for EXFLAG_INVALID after all calls > to x509v3_cache_extensions(). I agree that we should also port the other > changes but i'd rather do it in a follow-up diff.
Sure. > > > > I don't currently understand why your x509_vfy change was not done (and > > why they did not add a check to check_ca()). > > Also no idea, but they changed it again in: > https://github.com/openssl/openssl/commit/33328581b83e8e9f573f08f0e2e0d6b32d095857 I see. > With this, x509v3_cache_extensions() returns (x->ex_flags & EXFLAG_INVALID) > == 0 > and x509_check_ca() gets a check for the return value. Yes, I was going to suggest something along these lines as a follow-up. Having a void function which requires us to check for a flag is just silly. > This change also seems like something we should consider for the future imho. We need to be a bit careful due to the licensing... I don't think we want this as a public interface if we can help it. However, changing the signature of x509v3_cache_extensions() and absorbing the flag checks you add here would be great after the rest of the changes from #10756 is incorporated. ok tb > Index: x509/x509_purp.c > =================================================================== > RCS file: /cvs/src/lib/libcrypto/x509/x509_purp.c,v > retrieving revision 1.2 > diff -u -p -r1.2 x509_purp.c > --- x509/x509_purp.c 13 Sep 2020 15:06:17 -0000 1.2 > +++ x509/x509_purp.c 13 Mar 2021 19:49:01 -0000 > @@ -132,6 +132,8 @@ X509_check_purpose(X509 *x, int id, int > CRYPTO_w_lock(CRYPTO_LOCK_X509); > x509v3_cache_extensions(x); > CRYPTO_w_unlock(CRYPTO_LOCK_X509); > + if (x->ex_flags & EXFLAG_INVALID) > + return X509_V_ERR_UNSPECIFIED; > } > if (id == -1) > return 1; > @@ -421,7 +423,12 @@ setup_crldp(X509 *x) > { > int i; > > - x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL); > + x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, &i, NULL); > + if (x->crldp == NULL && i != -1) { > + x->ex_flags |= EXFLAG_INVALID; > + return; > + } > + > for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++) > setup_dp(x, sk_DIST_POINT_value(x->crldp, i)); > } > @@ -449,7 +456,7 @@ x509v3_cache_extensions(X509 *x) > x->ex_flags |= EXFLAG_V1; > > /* Handle basic constraints */ > - if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) { > + if ((bs = X509_get_ext_d2i(x, NID_basic_constraints, &i, NULL))) { > if (bs->ca) > x->ex_flags |= EXFLAG_CA; > if (bs->pathlen) { > @@ -463,10 +470,12 @@ x509v3_cache_extensions(X509 *x) > x->ex_pathlen = -1; > BASIC_CONSTRAINTS_free(bs); > x->ex_flags |= EXFLAG_BCONS; > + } else if (i != -1) { > + x->ex_flags |= EXFLAG_INVALID; > } > > /* Handle proxy certificates */ > - if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) { > + if ((pci = X509_get_ext_d2i(x, NID_proxyCertInfo, &i, NULL))) { > if (x->ex_flags & EXFLAG_CA || > X509_get_ext_by_NID(x, NID_subject_alt_name, -1) >= 0 || > X509_get_ext_by_NID(x, NID_issuer_alt_name, -1) >= 0) { > @@ -485,10 +494,12 @@ x509v3_cache_extensions(X509 *x) > x->ex_pcpathlen = -1; > PROXY_CERT_INFO_EXTENSION_free(pci); > x->ex_flags |= EXFLAG_PROXY; > + } else if (i != -1) { > + x->ex_flags |= EXFLAG_INVALID; > } > > /* Handle key usage */ > - if ((usage = X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) { > + if ((usage = X509_get_ext_d2i(x, NID_key_usage, &i, NULL))) { > if (usage->length > 0) { > x->ex_kusage = usage->data[0]; > if (usage->length > 1) > @@ -497,9 +508,12 @@ x509v3_cache_extensions(X509 *x) > x->ex_kusage = 0; > x->ex_flags |= EXFLAG_KUSAGE; > ASN1_BIT_STRING_free(usage); > + } else if (i != -1) { > + x->ex_flags |= EXFLAG_INVALID; > } > + > x->ex_xkusage = 0; > - if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) { > + if ((extusage = X509_get_ext_d2i(x, NID_ext_key_usage, &i, NULL))) { > x->ex_flags |= EXFLAG_XKUSAGE; > for (i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) { > switch (OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage, i))) > { > @@ -538,19 +552,27 @@ x509v3_cache_extensions(X509 *x) > } > } > sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free); > + } else if (i != -1) { > + x->ex_flags |= EXFLAG_INVALID; > } > > - if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) { > + if ((ns = X509_get_ext_d2i(x, NID_netscape_cert_type, &i, NULL))) { > if (ns->length > 0) > x->ex_nscert = ns->data[0]; > else > x->ex_nscert = 0; > x->ex_flags |= EXFLAG_NSCERT; > ASN1_BIT_STRING_free(ns); > + } else if (i != -1) { > + x->ex_flags |= EXFLAG_INVALID; > } > > - x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL); > - x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL); > + x->skid = X509_get_ext_d2i(x, NID_subject_key_identifier, &i, NULL); > + if (x->skid == NULL && i != -1) > + x->ex_flags |= EXFLAG_INVALID; > + x->akid = X509_get_ext_d2i(x, NID_authority_key_identifier, &i, NULL); > + if (x->skid == NULL && i != -1) > + x->ex_flags |= EXFLAG_INVALID; > > /* Does subject name match issuer? */ > if (!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x))) { > @@ -561,7 +583,9 @@ x509v3_cache_extensions(X509 *x) > x->ex_flags |= EXFLAG_SS; > } > > - x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL); > + x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, &i, NULL); > + if (x->altname == NULL && i != -1) > + x->ex_flags |= EXFLAG_INVALID; > x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL); > if (!x->nc && (i != -1)) > x->ex_flags |= EXFLAG_INVALID; > @@ -626,6 +650,8 @@ X509_check_ca(X509 *x) > CRYPTO_w_lock(CRYPTO_LOCK_X509); > x509v3_cache_extensions(x); > CRYPTO_w_unlock(CRYPTO_LOCK_X509); > + if (x->ex_flags & EXFLAG_INVALID) > + return X509_V_ERR_UNSPECIFIED; > } > > return check_ca(x); > @@ -837,7 +863,11 @@ X509_check_issued(X509 *issuer, X509 *su > X509_get_issuer_name(subject))) > return X509_V_ERR_SUBJECT_ISSUER_MISMATCH; > x509v3_cache_extensions(issuer); > + if (issuer->ex_flags & EXFLAG_INVALID) > + return X509_V_ERR_UNSPECIFIED; > x509v3_cache_extensions(subject); > + if (subject->ex_flags & EXFLAG_INVALID) > + return X509_V_ERR_UNSPECIFIED; > > if (subject->akid) { > int ret = X509_check_akid(issuer, subject->akid); > Index: x509/x509_verify.c > =================================================================== > RCS file: /cvs/src/lib/libcrypto/x509/x509_verify.c,v > retrieving revision 1.35 > diff -u -p -r1.35 x509_verify.c > --- x509/x509_verify.c 12 Mar 2021 15:53:38 -0000 1.35 > +++ x509/x509_verify.c 13 Mar 2021 19:49:01 -0000 > @@ -756,6 +756,10 @@ x509_verify_cert_extensions(struct x509_ > CRYPTO_w_lock(CRYPTO_LOCK_X509); > x509v3_cache_extensions(cert); > CRYPTO_w_unlock(CRYPTO_LOCK_X509); > + if (cert->ex_flags & EXFLAG_INVALID) { > + ctx->error = X509_V_ERR_UNSPECIFIED; > + return 0; > + } > } > > if (ctx->xsc != NULL)
