diff options
author | Matt Caswell <matt@openssl.org> | 2015-06-25 09:47:15 +0100 |
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committer | Matt Caswell <matt@openssl.org> | 2015-07-07 21:57:11 +0100 |
commit | aae41f8c54257d9fa6904d3a9aa09c5db6cefd0d (patch) | |
tree | dfdf107f25fc6355b6427091b8a178854c091d3b /crypto | |
parent | 593e9c638c58e1a510c519db0d024527113330f3 (diff) | |
download | openssl-aae41f8c54257d9fa6904d3a9aa09c5db6cefd0d.tar.gz |
Reject calls to X509_verify_cert that have not been reinitialised
The function X509_verify_cert checks the value of |ctx->chain| at the
beginning, and if it is NULL then it initialises it, along with the value
of ctx->untrusted. The normal way to use X509_verify_cert() is to first
call X509_STORE_CTX_init(); then set up various parameters etc; then call
X509_verify_cert(); then check the results; and finally call
X509_STORE_CTX_cleanup(). The initial call to X509_STORE_CTX_init() sets
|ctx->chain| to NULL. The only place in the OpenSSL codebase where
|ctx->chain| is set to anything other than a non NULL value is in
X509_verify_cert itself. Therefore the only ways that |ctx->chain| could be
non NULL on entry to X509_verify_cert is if one of the following occurs:
1) An application calls X509_verify_cert() twice without re-initialising
in between.
2) An application reaches inside the X509_STORE_CTX structure and changes
the value of |ctx->chain| directly.
With regards to the second of these, we should discount this - it should
not be supported to allow this.
With regards to the first of these, the documentation is not exactly
crystal clear, but the implication is that you must call
X509_STORE_CTX_init() before each call to X509_verify_cert(). If you fail
to do this then, at best, the results would be undefined.
Calling X509_verify_cert() with |ctx->chain| set to a non NULL value is
likely to have unexpected results, and could be dangerous. This commit
changes the behaviour of X509_verify_cert() so that it causes an error if
|ctx->chain| is anything other than NULL (because this indicates that we
have not been initialised properly). It also clarifies the associated
documentation. This is a follow up commit to CVE-2015-1793.
Reviewed-by: Stephen Henson <steve@openssl.org>
Diffstat (limited to 'crypto')
-rw-r--r-- | crypto/x509/x509_vfy.c | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c index 7a7fc59e77..7222113c68 100644 --- a/crypto/x509/x509_vfy.c +++ b/crypto/x509/x509_vfy.c @@ -193,6 +193,14 @@ int X509_verify_cert(X509_STORE_CTX *ctx) X509err(X509_F_X509_VERIFY_CERT, X509_R_NO_CERT_SET_FOR_US_TO_VERIFY); return -1; } + if (ctx->chain != NULL) { + /* + * This X509_STORE_CTX has already been used to verify a cert. We + * cannot do another one. + */ + X509err(X509_F_X509_VERIFY_CERT, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); + return -1; + } cb = ctx->verify_cb; @@ -200,15 +208,13 @@ int X509_verify_cert(X509_STORE_CTX *ctx) * first we make sure the chain we are going to build is present and that * the first entry is in place */ - if (ctx->chain == NULL) { - if (((ctx->chain = sk_X509_new_null()) == NULL) || - (!sk_X509_push(ctx->chain, ctx->cert))) { - X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE); - goto end; - } - CRYPTO_add(&ctx->cert->references, 1, CRYPTO_LOCK_X509); - ctx->last_untrusted = 1; + if (((ctx->chain = sk_X509_new_null()) == NULL) || + (!sk_X509_push(ctx->chain, ctx->cert))) { + X509err(X509_F_X509_VERIFY_CERT, ERR_R_MALLOC_FAILURE); + goto end; } + CRYPTO_add(&ctx->cert->references, 1, CRYPTO_LOCK_X509); + ctx->last_untrusted = 1; /* We use a temporary STACK so we can chop and hack at it */ if (ctx->untrusted != NULL |