Tag Archives: Apple

cURL and libcurl

Apple’s modified CA cert handling and curl

I tweeted about me finding a change in Apple’s version of curl that I haven’t seen any public patch for. Apple otherwise hosts a whole slew of curl patches which they never discuss with us about but still make public and we can see what they did.

I was trying to help out a fellow curl user on IRC (we’re in #curl on freenode, come see us) and he was trying to understand some funny effects of running curl against a HTTPS site and he showed me the output from a “curl -v” log. The verbose log curiously was different than mine (same curl version built by myself on Linux). My conclusion was that something was different in the Apple version.

The users log said:

* About to connect() to host.example.com port 443 (#0)
*   Trying 1.2.3.4... connected
* Connected to host.example.com (1.2.3.4) port 443 (#0)
* SSLv3, TLS handshake, Client hello (1):

… while my command against the same site said:

* About to connect() to host.example.com port 443 (#0)
*   Trying 1.2.3.4... connected
* Connected to host.example.com (1.2.3.4) port 443 (#0)
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: none
* SSLv3, TLS handshake, Client hello (1):

(I’ve bolded the part my output showed that wasn’t in the mac version, the real host name and IP have been changed.)

It seems I was wrong however.

The output above is only shown if libcurl sets the CA cert path to OpenSSL and it seems the Mac version doesn’t. Somehow they get the CA certs loaded to libcurl differently.

So ok, maybe they didn’t modify curl but they certainly changed how curl uses CA certs and they did this by modifying OpenSSL and clearly their version of OpenSSL now defaults to use their CA cert bundle. The end result for me is still the same though: I have no idea how CA certs work with curl on Mac so it leaves me with the unfortunate situation where I can’t help fellow curl users when they have CA cert problems on a Mac.

It also leaves me very curious on what –cacert does exactly on the mac version of curl.

OpenSSL is patched. Apparently it now works so that if the “normal” x509 validation fails, and TrustEvaluationAgent (TEA) is enabled, it will attempt to use the TEA to validate the certificate. The apple source code to read through for this is x509_vfy_apple.c in their patched OpenSSL tree. It is also possible to skip the TEA verification thing in OpenSSL by setting an environment variable, so that we can still have curl on mac act “as default” with a command line like:

$ env OPENSSL_X509_TEA_DISABLE=1 curl https://www.example.com/

Finally: yes, curl is released under an MIT license. They’re perfectly allowed to do whichever of these actions they want. I know this, and I chose the MIT license fully aware that any company can take the code, modify it and never return any changes. I’m not arguing against anyone’s rights to do this with curl.

Thank you, friendly anonymous helper for helping me straighten out my findings!

cURL and libcurl, Security

Apple – only 391 days behind

In the curl project, we take security seriously. We work hard to make sure we don’t open up for security problems of any kind and once we fail, we work hard at analyzing the problem and coming up with a proper fix as swiftly as possible to make our “customer” as little vulnerable as possible.

Recently I’ve been surprised and slightly shocked by the fact that a lot of open source operating systems didn’t release any security upgrades to our most recent security flaw until well over a month after we first publicized the flaw. I’m not sure why they all reacted so slowly. Possibly it is because vendor-sec isn’t quite working as they were informed prior to the notification, and of course I don’t really expect many security guys to be subscribed to the curl mailing lists. Slow distros include Debian and Mandriva while Redhat did great.

Today however, I got a mail from Apple (and no, I don’t know why they send these mails to me but I guess they think I need them or something) with the subject “APPLE-SA-2010-03-29-1 Security Update 2010-002 / Mac OS X v10.6.3“. Aha! Did Apple now also finally update their curl version you might think?

They did. But they did not fix this problem. They fixed two previous problems universally known as CVE-2009-0037 and CVE-2009-2417. Look at the date of that first one. March 3, 2009. Yes, a whopping 391 days after the problem was first made public, Apple sends out the security update. Cool. At least they eventually fixed the problem…