spnego_gssapi: implement TLS channel bindings for openssl #13098
Conversation
Foorack
force-pushed
the
openssl-spnego-channel-binding
branch
from
a0d34ca
to
7acadc0
Compare
|
"Linux / hyper" CI failed during |
lib/vtls/openssl.c
Outdated
| algo_type = EVP_sha256(); | ||
| } | ||
| else { | ||
| algo_type = EVP_get_digestbynid(algo_nid); | ||
| if(!algo_type) { | ||
| algo_name = OBJ_nid2sn(algo_nid); | ||
| failf(data, "Could not find digest algorithm %s (NID %d)", | ||
| algo_name ? algo_name : "(null)", algo_nid); | ||
| return CURLE_SSL_INVALIDCERTSTATUS; | ||
| } | ||
| } | ||
|
|
||
| if(!X509_digest(cert, algo_type, buf, &length)) { | ||
| failf(data, "X509_digest() failed"); | ||
| return CURLE_SSL_INVALIDCERTSTATUS; | ||
| } | ||
|
|
||
| *binding = malloc(sizeof(prefix) - 1 + length); | ||
| if(!*binding) | ||
| return CURLE_OUT_OF_MEMORY; | ||
| memcpy(*binding, prefix, sizeof(prefix) - 1); | ||
| memcpy(*binding + sizeof(prefix) - 1, buf, length); | ||
| *len = sizeof(prefix) - 1 + length; | ||
|
|
||
| return CURLE_OK; | ||
| #else | ||
| /* No X509_get_signature_nid support */ | ||
| (void)data; /* unused */ | ||
| (void)sockindex; /* unused */ | ||
| *binding = NULL; | ||
| *len = 0; | ||
| return CURLE_OK; | ||
| #endif | ||
| } |
There was a problem hiding this comment.
Would it be possible to avoid APIs that perform implicit fetching?
There was a problem hiding this comment.
Hello @DemiMarie! Sorry, but what do you mean by "implicit fetching"? Do you have an alternative API in mind?
There was a problem hiding this comment.
Hi @DemiMarie 👋 Please let me know if there is any outstanding requested changes on this; either if you have any alternative API's in mind, or if I can mark this conversation as resolved.
There was a problem hiding this comment.
“Implicit fetching” means calls like EVP_sha256(), as opposed to explicitly looking up the algorithm in a provider.
Foorack
force-pushed
the
openssl-spnego-channel-binding
branch
from
7acadc0
to
5b8c0eb
Compare
|
Rebased to bring PR up-to-date with master due to time passed. Minor changes
|
Foorack
force-pushed
the
openssl-spnego-channel-binding
branch
from
43c7a44
to
d916f49
Compare
Channel Bindings are used to tie the session context to a specific TLS channel. This is to provide additional proof of valid identity, mitigating authentication relay attacks. Major web servers have the ability to require (None/Accept/Require) GSSAPI channel binding, rendering Curl unable to connect to such websites unless support for channel bindings is implemented. IIS calls this feature Extended Protection (EPA), which is used in Enterprise environments using Kerberos for authentication. This change require krb5 >= 1.19, otherwise channel bindings won't be forwarded through SPNEGO. Co-Authored-By: Steffen Kieß <[email protected]>
Foorack
force-pushed
the
openssl-spnego-channel-binding
branch
from
d916f49
to
d776382
Compare
| return CURLE_SSL_INVALIDCERTSTATUS; | ||
| } | ||
| } | ||
|
|
||
| #if OPENSSL_VERSION_NUMBER >= 0x30000000L | ||
| algo_type = EVP_MD_fetch(NULL, algo_name, NULL); |
There was a problem hiding this comment.
It’s best to cache the result of this, for performance reasons.
Channel Bindings are used to tie the session context to a specific TLS channel. This is to provide additional proof of valid identity, mitigating authentication relay attacks.
Major web servers have the ability to require (None/Accept/Require) GSSAPI channel binding, rendering Curl unable to connect to such websites unless support for channel bindings is implemented.
IIS calls this feature Extended Protection (EPA), which is used in Enterprise environments using Kerberos for authentication.
This change require krb5 >= 1.19, otherwise channel bindings won't be forwarded through SPNEGO.