fix(jwe-decrypt): reject malformed tokens instead of returning 500 - #13844
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fix(jwe-decrypt): reject malformed tokens instead of returning 500#13844AlinsRan wants to merge 1 commit into
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A crafted JWE token makes the plugin throw a Lua error, so the request fails with 500 instead of the 400 the plugin already returns for invalid tokens: - a header segment that decodes to JSON `null` yields the truthy `cjson.null` userdata, and a scalar yields a number, so reading `kid` from it throws - an iv, ciphertext or tag that is not valid base64url decodes to nil, so `aes:new()` returns nil and calling `decrypt()` on it throws The consumer secret has the same problem: when data encryption is enabled the schema check cannot validate it, so a secret that is not valid base64url is accepted and `get_secret()` returns nil at request time. And when the check does run, `#base64.decode_base64url(secret)` throws on such a secret rather than reporting a schema error. Validate the decoded header, the token segments and the secret, and check the `aes:new()` return value, so all of these end up in the existing 400 response.
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Description
A crafted JWE token makes
jwe-decryptthrow a Lua error, so the request ends with a 500 instead of the 400 the plugin already returns for invalid tokens:core.json.decode()and only checked for truthiness. A header ofnulldecodes to the truthycjson.nulluserdata and a JSON scalar decodes to a number, sojwe_obj.header_obj.kidthrows:iv,ciphertextortagthat is not valid base64url decodes to nil.aes:new()then returnsnil, "iv is needed", and callingdecrypt()on it throws:Both are reachable with a single request against any route using the plugin, e.g.
The consumer secret has the same shape of problem.
check_schema()skips the length check when data encryption is enabled — which is the default — so asecretthat is not valid base64url is accepted, andget_secret()returns nil at request time, again ending in a 500. When the check does run (data_encryption.enable_encrypt_fields: false),#base64.decode_base64url(conf.secret)throws on such a secret instead of reporting a schema error.This PR validates the decoded header, the token segments and the secret, and checks the
aes:new()return value, so all of these paths end in the 400 the plugin already returns.Checklist
Tests: 5 new blocks in
t/plugin/jwe-decrypt.tcover thenullheader, a scalar header, invalid base64url token segments, a consumer secret that cannot be decoded at request time, and the schema error for a non-base64url secret. All five fail on master and pass with this change. No documentation change is needed: the plugin already documents 400 for an invalid token, and this only stops the malformed cases from escaping as 500.