Absent Input Validation in BinaryHttpParser

//netty-incubator-codec-ohttp/codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java

public final class BinaryHttpParser {
   ...
    private static BinaryHttpRequest readRequestHead(ByteBuf in, boolean knownLength, int maxFieldSectionSize) {
        ...
        final long pathLength = getVariableLengthInteger(in, pathLengthIdx, pathLengthBytes);
        ...
        final int pathIdx = pathLengthIdx + pathLengthBytes;
        ...
/*417*/ String method = in.toString(methodIdx, (int) methodLength, StandardCharsets.US_ASCII);
/*418*/ String scheme = in.toString(schemeIdx, (int) schemeLength, StandardCharsets.US_ASCII);
/*419*/ String authority = in.toString(authorityIdx, (int) authorityLength, StandardCharsets.US_ASCII);
/*420*/ String path = in.toString(pathIdx, (int) pathLength, StandardCharsets.US_ASCII);

/*422*/ BinaryHttpRequest request = new DefaultBinaryHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.valueOf(method),
                scheme, authority, path, headers);
        in.skipBytes(sumBytes);
        return request;
    }
   ...
}

Request Method On line 422 above, the parsed method value is passed into HttpMethod.valueOf method. The return value from this is passed to the DefaultBinaryHttpRequest constructor.

Below is the code for HttpMethod.valueOf:

    public static HttpMethod valueOf(String name) {
        // fast-path
        if (name == HttpMethod.GET.name()) {
            return HttpMethod.GET;
        }
        if (name == HttpMethod.POST.name()) {
            return HttpMethod.POST;
        }
        // "slow"-path
        HttpMethod result = methodMap.get(name);
        return result != null ? result : new HttpMethod(name);
    }

If the result of methodMap.get is not null, then a new arbitrary HttpMethod instance will be returned using the provided name value.

methodMap is an instance of type EnumNameMap which is also defined within the HttpMethod class:

        EnumNameMap(Node<T>... nodes) {
            this.values = (Node[])(new Node[MathUtil.findNextPositivePowerOfTwo(nodes.length)]);
            this.valuesMask = this.values.length - 1;
            Node[] var2 = nodes;
            int var3 = nodes.length;

            for(int var4 = 0; var4 < var3; ++var4) {
                Node<T> node = var2[var4];
                int i = hashCode(node.key) & this.valuesMask;
                if (this.values[i] != null) {
                    throw new IllegalArgumentException("index " + i + " collision between values: [" + this.values[i].key + ", " + node.key + ']');
                }

                this.values[i] = node;
            }

        }

        T get(String name) {
            Node<T> node = this.values[hashCode(name) & this.valuesMask];
            return node != null && node.key.equals(name) ? node.value : null;
        }

Note that EnumNameMap.get() returns a boolean value, which is not null. Therefore, any arbitrary http verb used within a BinaryHttpRequest will yield a valid HttpMethod object. When the HttpMethod object is constructed, the name is checked for whitespace and similar characters. Therefore, we cannot perform complete injection attacks using the HTTP verb alone. However, when combined with the other input validation issues, such as that in the path field, we can construct somewhat arbitrary data blobs that satisfy text-based protocol message formats.

Impact

Method is partially validated while other values are not validated at all. Software that relies on netty to apply input validation for binary HTTP data may be vulnerable to various injection and protocol based attacks.