Restrict UI theme file loader to JSON files under the theme config dir#1391
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TristanInSec wants to merge 1 commit into
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Restrict UI theme file loader to JSON files under the theme config dir#1391TristanInSec wants to merge 1 commit into
TristanInSec wants to merge 1 commit into
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extractUITheme accepts a path value that originates from the POST /updateTheme HTTP handler, and currently passes it straight to __non_webpack_require__. Because require() can load both .json and .js modules from anywhere on the filesystem, the handler is effectively a general-purpose file loader whose output is exposed back to the UI via window.CDAP_UI_THEME. Replace the require-based loader with a narrower implementation: - resolveAllowedThemePath() canonicalises the supplied path (handling the existing server/ and config/ relative-path shortcuts) and rejects anything whose resolved location is not inside one of the UI theme config directories. - The resolver enforces a .json extension, so the loader can no longer be pointed at a .js module. - Loading switches from __non_webpack_require__ to fs.readFileSync + JSON.parse, so non-JSON contents cannot be executed even if the path check were ever weakened. The public extractUITheme signature and return shape are unchanged, so the two callers (extractUIThemeWrapper and the /updateTheme handler) keep working with the legitimate theme paths (config/themes/light.json, server/config/themes/default.json, etc.).
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Hi @chtyim @ajainarayanan, friendly ping on this security fix and the related #1392, #1393, #1394. CLA is passing, happy to make any changes needed. Thanks! |
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Summary
server/uiThemeWrapper.jscurrently loads the UI theme file by passing the caller-supplied path straight to__non_webpack_require__. ThePOST /updateThemehandler inserver/express.jsfeeds this function a path taken from the request body, so the effective contract is "load any file reachable byrequire()and expose its contents to the UI throughwindow.CDAP_UI_THEME".This PR narrows that contract:
resolveAllowedThemePath()helper canonicalises the supplied path (keeping the existingserver/andconfig/relative-path shortcuts) and refuses to return anything that does not resolve to a location inside one of the UI theme config directories..jsonextension. The resolver rejects paths with any other extension, so the loader can no longer be pointed at a.jsmodule.require()tofs.readFileSync+JSON.parse. Even if the allowlist check were ever weakened, the loaded file is no longer executed as a Node module.The exported
extractUITheme(cdapConfig, uiThemePath)signature and return shape are unchanged; the two existing callers (extractUIThemeWrapperand the/updateThemeexpress handler) continue to work with the legitimate theme paths shipped inserver/config/themes/(default.json,light.json).Testing
I exercised the new resolver in isolation against the server's
config/themesdirectory and confirmed:config/themes/light.jsonserver/config/themes/../../../etc/passwd/etc/cdap/conf/cdap-site.jsonconfig/themes/evil.jsconfig/themes/../../etc/passwd.json''default.jsonandlight.jsoncontinue to load identically to the previous implementation.