From f4569b14c477efc28f7793246d4ad8877ed941d0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= Date: Thu, 19 Nov 2015 09:23:06 +0100 Subject: [PATCH] Fix bug checking pathlen on first intermediate Remove check on the pathLenConstraint value when looking for a parent to the EE cert, as the constraint is on the number of intermediate certs below the parent, and that number is always 0 at that point, so the constraint is always satisfied. The check was actually off-by-one, which caused valid chains to be rejected under the following conditions: - the parent certificate is not a trusted root, and - it has pathLenConstraint == 0 (max_pathlen == 1 in our representation) fixes #280 --- ChangeLog | 7 +++++++ library/x509_crt.c | 10 ---------- 2 files changed, 7 insertions(+), 10 deletions(-) diff --git a/ChangeLog b/ChangeLog index 8a736f971..6d8a5bca7 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,12 @@ mbed TLS ChangeLog (Sorted per branch, date) += mbed TLS 2.x branch + +Bugfix + * Fix bug in certificate validation that caused valid chains to be rejected + when the first intermediate certificate has pathLenConstraint=0. Found by + Nicholas Wilson. Introduced in mbed TLS 2.2.0. #280 + = mbed TLS 2.2.0 released 2015-11-04 Security diff --git a/library/x509_crt.c b/library/x509_crt.c index 91e4f50b9..6dc5ad34f 100644 --- a/library/x509_crt.c +++ b/library/x509_crt.c @@ -2253,18 +2253,8 @@ int mbedtls_x509_crt_verify_with_profile( mbedtls_x509_crt *crt, { /* Look for a parent upwards the chain */ for( parent = crt->next; parent != NULL; parent = parent->next ) - { - /* +2 because the current step is not yet accounted for - * and because max_pathlen is one higher than it should be */ - if( parent->max_pathlen > 0 && - parent->max_pathlen < 2 + pathlen ) - { - continue; - } - if( x509_crt_check_parent( crt, parent, 0, pathlen == 0 ) == 0 ) break; - } /* Are we part of the chain or at the top? */ if( parent != NULL )