Refactoring was required to allow for embedded certs. The existing
eap_tls_state object was changed to hold the cert types (l_queue,
l_certchain, l_key) rather than the file path, since there may not
actually be separate PEM files.
Care was taken to properly manage the memory of these objects.
Since the TLS object takes ownership when setting auth data or the
CA certs all error cases must be handled properly to free these
objects after they are loaded and in addition they must be set to
NULL so that the cleanup doesn't double free them.
If everything goes to plan, we load all the PEMs in settings_load,
provide these objects to the TLS APIs, and then NULL out the
pointers (TLS now owns this memory). If anything fails between
settings_load and l_tls_start we must free these objects.
A special format must be used to indicate that a PEM is embedded
inside the settings file. First, the l_settings format should be
followed for the PEM itself, e.g.
[@pem@my_ca_cert]
<CA Cert data>
This PEM can then be referenced by "embed:my_ca_cert", e.g.
EAP-TLS-CACert=embed:my_ca_cert
Any other value not starting with "embed:" will be treated as a file
path.
Allow users to provide a glob string that the contents of the server
certificate's subject DN should be matched against as a primitive
protection against rogue APs using certificates purchased from
commercial CAs trusted by the client. If the network uses an AP
certificate emitted by a commerical CA and the clients are configured
to trust those CAs so that the client configurations don't have to be
updated when the AP renews its certificate, this new option can be used
to check if the CN in the AP certificate's DN matches the known domain
name. This logic assumes that the commercial CAs provide enough
assurance that only the owner of the domain can buy a certificate with
that domain in the CN field.
The format of this option is similar to apple's TLSTrustedServerNames
and wpa_supplicant's domain_match/domain_suffix_match format, the exact
syntax is documented in ell/tls.c.
The Hotspot 2.0 spec introduces 'Anonymous EAP-TLS' as a new EAP method
to be used with OSEN/Hotspot. The protocol details of this aren't
relevant to this patch, but one major difference is that it uses the
expanded EAP type rather than the TLS type. Since the common TLS code
was written with only EAP_TYPE_TLS in mind the vendor ID/type cause the
EAP packet to be malformed when using the expanded EAP type.
To handle this the common TLS code now checks the EAP type, and if its
expanded we shift the payload 7 bytes further to account for the extra
header data.
Replace existing uses of memset to clear secrets with explicit_bzero to
make sure it doesn't get optimized away. This has some side effects as
documented in gcc docs but is still recommended.
In eap_secret_info_free make sure we clear both strings in the case of
EAP_SECRET_REMOTE_USER_PASSWORD secrets.
In the methods' check_settings do a more complete early check for
possible certificate / private key misconfiguration, including check
that the certificate and the private key are always present or absent
together and that they actually match each other. Do this by encrypting
and decrypting a small buffer because we have no better API for that.
Stop using l_pem_load_certificate which has been removed from ell, use
the same functions to load certificate files to validate them as those
used by the TLS implementation itself.
Check that the TLS logic has verified the server is trusted by the CA if
one was configured. This is more of an assert as ell intentionally only
allows empty certificate chains from the peer in server mode (if a CA
certficate is set) although this could be made configurable.
