SslBump: Support bump-ssl-server-first and mimic SSL server certificates.
Summary: These changes allow Squid working in SslBump mode to peek at
the origin server certificate and mimic peeked server certificate
properties in the generated fake certificate, all prior to establishing
a secure connection with the client:
http://wiki.squid-cache.org/Features/BumpSslServerFirst
http://wiki.squid-cache.org/Features/MimicSslServerCert
The changes are required to bump intercepted SSL connections without
excessive browser warnings. The changes allow to disable bumping of some
intercepted SSL connections, forcing Squid to go into a TCP tunnel mode
for those connections.
The changes also empower end user to examine and either honor or bypass
most origin SSL server certificate errors. Prior to these changes, the
responsibility for ignoring certificate validation errors belonged
exclusively to Squid, necessarily leaving users in the dark if errors
are ignored/bypassed.
Squid can still be configured to emulate old bump-ssl-client-first
behavior. However, a manual revision of ssl_bump options is required
during upgrade because ssl_bump no longer supports an implicit "negate
the last one" rule (and it is risky to let Squid guess what the admin
true intent was or mix old- and new-style rules).
Finally, fake certificate generation has been significantly improved.
The new code guarantees that all identically configured Squids receiving
identical origin server certificates will generate identical fake
certificates, even if those Squid instances are running on different
hosts, at different times, and do not communicate with each other. Such
stable, reproducible certificates are required for distributed,
scalable, or fail-safe Squid deployment.
Overall, the changes are meant to make SslBump more powerful and safer.
The code has been tested in several independent labs.
Specific major changes are highlighted below:
Make bumping algorithm selectable using ACLs. Even though
bump-server-first is an overall better method, bumping the client first
is useful for backward compatibility and possibly for serving internal
Squid objects (such as icons inside Squid error pages). The following
example bumps special and most other requests only, using the old
bump-client-first approach for the special requests only:
ssl_bump client-first specialOnes
ssl_bump server-first mostOthers
ssl_bump none all
It allow use the old ssl_bump syntax:
ssl_bump allow/deny acl ...
but warns the user to update squid configuration.
Added sslproxy_cert_adapt squid.conf option to overwrite default mimicking
behavior when generating SSL certificates. See squid.conf.documented.
Added sslproxy_cert_sign squid.conf option to control how generated SSL
certificates are signed. See squid.conf.documented.
Added ssl::certHasExpired, ssl::certNotYetValid, ssl::certDomainMismatch,
ssl::certUntrusted, and ssl::certSelfSign predefined ACLs to squid.conf.
Do not require http[s]_port's key option to be set if cert option is given.
The fixed behavior for bumped connections now matches squid.conf docs.
Generate stable fake certificates by using signing and true certificate
hashes as the serial number and by using the configured CA private key
for all fake certificates.
Use minimal, trusted certificate for serving SSL errors to the client
instead of trying to mimic the broken true certificate (which results
in double error for the user: browser error dialog plus Squid error page).
To mimic "untrusted" true certificates, generate an untrusted CA certificate
from the configured trusted CA certificate. This both reduces configuration
effort (compared to a configuration option) and results in identical
untrusted fake certificates given identical Squid configurations.
Intelligent handling of CONNECT denials: Do not connect to origin
servers unless CONNECT is successfully authenticated. Delay errors.Added sslproxy_cert_sign squid.conf option to control how generated SSL
certificates are signed. See squid.conf.documented.
Provide '%I' error page formatting code with enough information to avoid
displaying '[unknown]' on SQUID_X509_V_ERR_DOMAIN_MISMATCH errors.
Set logged status code (%<Hs) to 200 when establishing a bumped tunnel.
Improved error detailing and logging: Forget most retried errors.
During SslBump errors, the error details are now logged with both the
initial CONNECT transaction and the first tunneled HTTP transaction.
Do not report system errors as custom Squid errors. Do not report
system errors that did not necessarily happen during the transaction
being logged.
Check SSL server certificate when reconnecting to the origin server for
bumped requests. Despite pinning, Squid maintains two separate connections
and the server may disconnect while the client is still sending requests. To
minimize deployment problems, we reconnect to the origin server but check
that its certificate (which we mimicked for the client) has not changed
much.
Forward bumped server connection-close signal to the bumped client to
improve the "dumb tunnel" appearance of the bumped SSL tunnel.
Allow bumping of CONNECT requests without allow-direct set on http_port.
Previously, that flag was required to allow bumped requests to go direct
because they were (and, sometimes, still are) considered "accelerated".
Send SNI information to the server when server-first bumping a non-IP
CONNECT request.
Better helper-to-Squid buffer size management to support large certificates.
Bypass rare OpenSSL certificate serialization failures when composing an
ssl_crtd request by generating the certificate in the Squid process.
When generating certificate CN names, strip [] surrounding host names,
assuming they are for IPv6 addresses. Bracketed CNs confuse browsers.
Disable persistent connections after client-side-detected errors. They cause
"abandoning such and such connection" warnings, stuck ConnStateData jobs, and
other problems.
HttpRequest::SetHost() must invalidate HttpRequest::canonical "cache".
Implement ssl::bump_mode logformat code to log SslBump decisions: prints "none",
"client-first", "server-first" or "-" for no ssl-bump enabled ports
Synced with trunk (trunk r12216, v3.2.0.18+)
This is a Measurement Factory project.
projects / thirdparty / squid.git / commitdiff
