diff options
| author | David Benjamin <davidben@google.com> | 2017-09-18 16:51:56 -0400 |
|---|---|---|
| committer | Andy Polyakov <appro@openssl.org> | 2017-09-22 22:00:55 +0200 |
| commit | 8545051c3652bce7bb962afcb6879c4a6288bc67 (patch) | |
| tree | 03f47ed1bb5c20496f6ed891540e0490265791df /crypto/x509/x509_vfy.c | |
| parent | 79b4444d81e2b9f21c60d7bf6511200e3e41d6fd (diff) | |
Guard against DoS in name constraints handling.
This guards against the name constraints check consuming large amounts
of CPU time when certificates in the presented chain contain an
excessive number of names (specifically subject email names or subject
alternative DNS names) and/or name constraints.
Name constraints checking compares the names presented in a certificate
against the name constraints included in a certificate higher up in the
chain using two nested for loops.
Move the name constraints check so that it happens after signature
verification so peers cannot exploit this using a chain with invalid
signatures. Also impose a hard limit on the number of name constraints
check loop iterations to further mitigate the issue.
Thanks to NCC for finding this issue. Fix written by Martin Kreichgauer.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Andy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4393)
Diffstat (limited to 'crypto/x509/x509_vfy.c')
| -rw-r--r-- | crypto/x509/x509_vfy.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c index fd297e2082..d4a5f3a6ba 100644 --- a/crypto/x509/x509_vfy.c +++ b/crypto/x509/x509_vfy.c @@ -217,7 +217,6 @@ static int verify_chain(X509_STORE_CTX *ctx) if ((ok = build_chain(ctx)) == 0 || (ok = check_chain_extensions(ctx)) == 0 || (ok = check_auth_level(ctx)) == 0 || - (ok = check_name_constraints(ctx)) == 0 || (ok = check_id(ctx)) == 0 || 1) X509_get_pubkey_parameters(NULL, ctx->chain); if (ok == 0 || (ok = ctx->check_revocation(ctx)) == 0) @@ -235,6 +234,9 @@ static int verify_chain(X509_STORE_CTX *ctx) if (!ok) return ok; + if ((ok = check_name_constraints(ctx)) == 0) + return ok; + #ifndef OPENSSL_NO_RFC3779 /* RFC 3779 path validation, now that CRL check has been done */ if ((ok = X509v3_asid_validate_path(ctx)) == 0) |