diff options
author | Matt Caswell <matt@openssl.org> | 2015-06-25 09:47:15 +0100 |
---|---|---|
committer | Matt Caswell <matt@openssl.org> | 2015-07-07 22:52:36 +0100 |
commit | b3b1eb5735c5b3d566a9fc3bf745bf716a29afa0 (patch) | |
tree | 846d4d4e6a3e9a7e164f869893fcff81f211965b /crypto/x509 | |
parent | d42d1004332f40c1098946b0804791fd3da3e378 (diff) |
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/x509')
-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 a0083b552d..2e4c54b816 100644 --- a/crypto/x509/x509_vfy.c +++ b/crypto/x509/x509_vfy.c @@ -162,6 +162,14 @@ 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; @@ -169,15 +177,13 @@ 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 |