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OCPBUGS-87205: Strip X-SSL-Client-* headers for plain HTTP #787

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OCPBUGS-87205: Strip X-SSL-Client-* headers for plain HTTP #787

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2e0ec41
OCPBUGS-86718: Strip X-SSL-Client-* headers for plain HTTP
bentito Jun 4, 2026
ef98dff
Rename env var to ROUTER_MUTUAL_TLS_HEADER_FILTER
bentito Jun 4, 2026
fca5221
Expand list of stripped X-SSL-Client-* headers
bentito Jun 4, 2026
861e7c2
Update images/router/haproxy/conf/haproxy-config.template
bentito Jun 4, 2026
d180c82
OCPBUGS-87205: fix comments on template
rikatz Jun 8, 2026
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53 changes: 53 additions & 0 deletions images/router/haproxy/conf/haproxy-config.template
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Original file line number Diff line number Diff line change
Expand Up @@ -273,6 +273,23 @@ frontend public
# Strip off Proxy headers to prevent HTTpoxy (https://httpoxy.org/)
http-request del-header Proxy

# Strip off X-SSL* headers for plain HTTP if not explicitly disabled.
# This prevents unauthenticated spoofing of mutual TLS client identities.
{{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}

@Miciah Miciah Jun 8, 2026

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The indentation of these Go template stanzas is inconsistent with surrounding Go template stanzas, but the template already has similar inconsistencies elsewhere; we can fix them all up in a follow-up.

http-request del-header X-SSL
http-request del-header X-SSL-Client-CN
http-request del-header X-SSL-Client-DER
http-request del-header X-SSL-Client-DN
http-request del-header X-SSL-Client-NotAfter
http-request del-header X-SSL-Client-NotBefore
http-request del-header X-SSL-Client-SHA1
http-request del-header X-SSL-Client-Serial
http-request del-header X-SSL-Client-Subject

@Miciah Miciah Jun 8, 2026

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Where is X-SSL-Client-Subject added? Why does it need to be deleted?

@rikatz rikatz Jun 8, 2026

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While we don't set them on router, I think it is a valid deletion. This header can also be used for authentication, in case some day we decide to add it to router passing to backend by a customer request we can run on a problem of forgetting to remove it

@Miciah Miciah Jun 9, 2026

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It seems arbitrary. Why not also add http-request del-header X-SSL-Client-Chain-DER or http-request del-header X-SSL-Client-Used or other arbitrary things that an application could theoretically use or HAProxy could theoretically set?

http-request del-header X-SSL-Client-Verify
http-request del-header X-SSL-Client-Version
http-request del-header X-SSL-Issuer
{{- end }}

# DNS labels are case insensitive (RFC 4343), we need to convert the hostname into lowercase
# before matching, or any requests containing uppercase characters will never match.
http-request set-header Host %[req.hdr(Host),lower]
Expand Down Expand Up @@ -390,6 +407,24 @@ frontend fe_sni
# Strip off Proxy headers to prevent HTTpoxy (https://httpoxy.org/)
http-request del-header Proxy

# Strip off X-SSL* headers if not explicitly disabled.
# This prevents unauthenticated spoofing of mutual TLS client identities
# when mutual TLS is not enabled and so the headers are not set below.
{{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}
http-request del-header X-SSL
http-request del-header X-SSL-Client-CN
http-request del-header X-SSL-Client-DER
http-request del-header X-SSL-Client-DN
http-request del-header X-SSL-Client-NotAfter
http-request del-header X-SSL-Client-NotBefore
http-request del-header X-SSL-Client-SHA1
http-request del-header X-SSL-Client-Serial
http-request del-header X-SSL-Client-Subject
http-request del-header X-SSL-Client-Verify
http-request del-header X-SSL-Client-Version
http-request del-header X-SSL-Issuer
{{- end }}

# DNS labels are case insensitive (RFC 4343), we need to convert the hostname into lowercase
# before matching, or any requests containing uppercase characters will never match.
http-request set-header Host %[req.hdr(Host),lower]
Expand Down Expand Up @@ -505,6 +540,24 @@ frontend fe_no_sni
# Strip off Proxy headers to prevent HTTpoxy (https://httpoxy.org/)
http-request del-header Proxy

# Strip off X-SSL* headers if not explicitly disabled.
# This prevents unauthenticated spoofing of mutual TLS client identities
# when mutual TLS is not enabled and so the headers are not set below.
{{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}
http-request del-header X-SSL
http-request del-header X-SSL-Client-CN
http-request del-header X-SSL-Client-DER
http-request del-header X-SSL-Client-DN
http-request del-header X-SSL-Client-NotAfter
http-request del-header X-SSL-Client-NotBefore
http-request del-header X-SSL-Client-SHA1
http-request del-header X-SSL-Client-Serial
http-request del-header X-SSL-Client-Subject
http-request del-header X-SSL-Client-Verify
http-request del-header X-SSL-Client-Version
http-request del-header X-SSL-Issuer
{{- end }}

# DNS labels are case insensitive (RFC 4343), we need to convert the hostname into lowercase
# before matching, or any requests containing uppercase characters will never match.
http-request set-header Host %[req.hdr(Host),lower]
Expand Down