fix: Panics when passing a malformed GitSession #3058
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kolesnikovae
approved these changes
Feb 29, 2024
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IV size (nonce) size is determined in the oauth2-proxy (uses the standard size 12) and ideally should be verified at decryption inside the library (e.g., here), – it's very unlikely that it will change, so I think it's ok to do it on our side. OTOH, I'm not sure if we benefit from use of oauth2-proxy dependency
cyriltovena
reviewed
Feb 29, 2024
| func decryptToken(encodedText string, key []byte) (*oauth2.Token, error) { | ||
| encryptedData, err := base64.StdEncoding.DecodeString(encodedText) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| if len(encryptedData) < gcmNonceSize { |
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I suspect we need to recover panic in this function or above too just in case ?
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Yeah, we should. Shouldn't all recoverable panics get caught by the grpc handler? Why doesn't this happen today?
Co-authored-by: Christian Simon <simon@swine.de>
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If a carefully chosen
GitSessionis passed to the backend, it causes an out of range panic and crash. This isn't ideal as attackers will have a way to continually crash queriers.If
GitSessionis a valid base64 encoding which, when decoded, results in a cipher text less than the chose GCM Cipher nonce size, the decryption subroutine will try split the cipher text into two parts, a "nonce" part and a "rest" part. if the cipher text is shorter than the "nonce" part, it panics.See: https://github.com/oauth2-proxy/oauth2-proxy/blob/e3dc927e570700ae598425344cf07073965bd19c/pkg/encryption/cipher.go#L124-L125
As far as I can tell, the nonce size is always 12, though I don't know how reliably we can depend on this.