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Diffstat (limited to 'toolkit/components/resistfingerprinting/docs')
| -rw-r--r-- | toolkit/components/resistfingerprinting/docs/implementation.rst | 78 | ||||
| -rw-r--r-- | toolkit/components/resistfingerprinting/docs/index.rst | 8 |
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diff --git a/toolkit/components/resistfingerprinting/docs/implementation.rst b/toolkit/components/resistfingerprinting/docs/implementation.rst new file mode 100644 index 0000000000..9e8a7491d4 --- /dev/null +++ b/toolkit/components/resistfingerprinting/docs/implementation.rst @@ -0,0 +1,78 @@ +========================= +Implementation +========================= + +Checking if an object should resist fingerprinting is ideally done by referencing the `Document's ShouldResistFingerprinting <https://searchfox.org/mozilla-central/search?q=symbol:_ZNK7mozilla3dom8Document26ShouldResistFingerprintingENS_9RFPTargetE&redirect=false>`_ method. This is both fast and correct. In certain other situations, you may need to call some of the ``nsContentUtils::ShouldResistFingerprinting`` functions. When doing so, you should avoid calling either of the functions marked *dangerous*. + +As you can see in the callgraph below, directly calling a *dangerous* function will skip some of the checks that occur further up-stack. + +.. mermaid:: + + graph TD + SRFP["ShouldResistFingerprinting()"] + click SRFP href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils26ShouldResistFingerprintingEN7mozilla9RFPTargetE&redirect=false" + + SRGP_GO["ShouldResistFingerprinting(nsIGlobalObject* aGlobalObject"] + click SRGP_GO href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils26ShouldResistFingerprintingEP15nsIGlobalObjectN7mozilla9RFPTargetE&redirect=false" + + GO_SRFP["nsIGlobalObject*::ShouldResistFingerprinting()"] + click GO_SRFP href "https://searchfox.org/mozilla-central/search?q=symbol:_ZNK15nsIGlobalObject26ShouldResistFingerprintingEN7mozilla9RFPTargetE&redirect=false" + + Doc_SRFP["Document::ShouldResistFingerprinting()<br />System Principal Check"] + click Doc_SRFP href "https://searchfox.org/mozilla-central/search?q=symbol:_ZNK7mozilla3dom8Document26ShouldResistFingerprintingENS_9RFPTargetE&redirect=false" + + SRFP_char["ShouldResistFingerprinting(const char*)"] + click SRFP_char href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils26ShouldResistFingerprintingEPKcN7mozilla9RFPTargetE&redirect=false" + + SRFP_callertype_go["ShouldResistFingerprinting(CallerType, nsIGlobalObject*)<br />System Principal Check"] + click SRFP_callertype_go href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils26ShouldResistFingerprintingEN7mozilla3dom10CallerTypeEP15nsIGlobalObjectNS0_9RFPTargetE&redirect=false" + + SRFP_docshell["ShouldResistFingerprinting(nsIDocShell*)"] + click SRFP_docshell href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils26ShouldResistFingerprintingEP11nsIDocShellN7mozilla9RFPTargetE&redirect=false" + + SRFP_channel["ShouldResistFingerprinting(nsIChannel*)<br />ETPSaysShouldNotResistFingerprinting Check<br />CookieJarSettingsSaysShouldResistFingerprinting Check"] + click SRFP_channel href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils26ShouldResistFingerprintingEP10nsIChannelN7mozilla9RFPTargetE&redirect=false" + + SRFP_uri["ShouldResistFingerprinting_dangerous(nsIURI*, OriginAttributes)<br />PBM Check<br />Scheme (inc WebExtension) Check<br />About Page Check<br />URI & Partition Key Exempt Check"] + click SRFP_uri href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils36ShouldResistFingerprinting_dangerousEP6nsIURIRKN7mozilla16OriginAttributesEPKcNS2_9RFPTargetE&redirect=false" + + SRFP_principal["ShouldResistFingerprinting_dangerous(nsIPrincipal*)<br />System Principal Check<br />PBM Check<br />Scheme Check<br />About Page Check<br />Web Extension Principal Check<br />URI & Partition Key Exempt Check"] + click SRFP_principal href "https://searchfox.org/mozilla-central/search?q=symbol:_ZN14nsContentUtils36ShouldResistFingerprinting_dangerousEP12nsIPrincipalPKcN7mozilla9RFPTargetE&redirect=false" + + + + + SRFP_principal --> |null| SRFP_char + + SRFP_uri --> |null| SRFP_char + + SRFP_channel -->|null| SRFP_char + SRFP_channel --> |Document Load| SRFP_uri + SRFP_channel --> |Subresource Load| SRFP_principal + + SRFP_docshell -->|null| SRFP_char + SRFP_docshell --> Doc_SRFP + + SRFP_callertype_go --> SRGP_GO + SRFP_char --> SRFP + SRGP_GO -->|null| SRFP_char + SRGP_GO --> GO_SRFP + + GO_SRFP --> |innerWindow, outerWindow| Doc_SRFP + Doc_SRFP --> SRFP_channel + + +Exemptions and Targets +~~~~~~~~~~~~~~~~~~~~~~ + +Fingerprinting Resistance takes into account many things to determine if we should alter behavior: + +* Whether we are the System Principal +* Whether we are a Web Extension +* Whether Fingerprinting Resistance is applied to all browsing modes or only Private Browsing Mode +* Whether the specific site you are visiting has been granted an exemption (taking into account the framing page) +* Whether the specific **activity** is granted an exemption + +All callsites for ``ShouldResistFingerprinting`` take a (currently) optional ``RFPTarget`` value, which defaults to ``Unknown``. While arguments such as ``Document`` or ``nsIChannel`` provide context for the first four exemptions above, the Target provides context for the final one. A Target is a Web API or an activity - such as a Pointer Event, the Screen Orientation, or plugging a gamepad into your computer (and therefore producing a `gamepadconnected event <https://www.w3.org/TR/gamepad/#event-gamepadconnected>`_). Most Targets correlate strongly to a specific Web API, but not all do: for example whether or not to automatically reject Canvas extraction requests from third parties is a separate Target from prompting to reject canvas extraction. + +In some situations we may *not* alter our behavior for a certain activity - this could be based on the fingerprinting resistance mode you are using, or per-site overrides to correct breakage. Targets are defined `RFPTargets.inc <https://searchfox.org/mozilla-central/source/toolkit/components/resistfingerprinting/RFPTargets.inc>`_. diff --git a/toolkit/components/resistfingerprinting/docs/index.rst b/toolkit/components/resistfingerprinting/docs/index.rst new file mode 100644 index 0000000000..57bb24beac --- /dev/null +++ b/toolkit/components/resistfingerprinting/docs/index.rst @@ -0,0 +1,8 @@ +========================= +Fingerprinting Resistance +========================= + +.. toctree:: + :maxdepth: 1 + + implementation |