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#
# Author:: Christopher Brown (<cb@opscode.com>)
# Copyright:: Copyright (c) 2009 Opscode, Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
require 'ostruct'
require 'net/http'
require 'mixlib/authentication'
require 'mixlib/authentication/signedheaderauth'
module Mixlib
module Authentication
class SignatureVerification
include Mixlib::Authentication::SignedHeaderAuth
attr_reader :hashed_body, :timestamp, :http_method, :user_id
# Takes the request, boils down the pieces we are interested in,
# looks up the user, generates a signature, and compares to
# the signature in the request
# ====Headers
#
# X-Ops-Sign: algorithm=sha256;version=1.0;
# X-Ops-UserId: <user_id>
# X-Ops-Timestamp:
# X-Ops-Content-Hash:
# X-Ops-Authorization-#{line_number}
def authenticate_user_request(request, user_lookup, time_skew=(15*60))
Mixlib::Authentication::Log.debug "Initializing header auth : #{request.inspect}"
headers ||= request.env.inject({ }) { |memo, kv| memo[$2.gsub(/\-/,"_").downcase.to_sym] = kv[1] if kv[0] =~ /^(HTTP_)(.*)/; memo }
digester = Mixlib::Authentication::Digester.new
begin
@allowed_time_skew = time_skew # in seconds
@http_method = request.method.to_s
@signing_description = headers[:x_ops_sign].chomp
@user_id = headers[:x_ops_userid].chomp
@timestamp = headers[:x_ops_timestamp].chomp
@host = headers[:host].chomp
@content_hash = headers[:x_ops_content_hash].chomp
@user_secret = user_lookup
# The authorization header is a Base64-encoded version of an RSA signature.
# The client sent it on multiple header lines, starting at index 1 -
# X-Ops-Authorization-1, X-Ops-Authorization-2, etc. Pull them out and
# concatenate.
# if there are 11 headers, the sort breaks - it becomes lexicographic sort rather than numeric [cb]
@request_signature = headers.find_all { |h| h[0].to_s =~ /^x_ops_authorization_/ }.sort { |x,y| x.to_s <=> y.to_s}.map { |i| i[1] }.join("\n")
Mixlib::Authentication::Log.debug "Reconstituted request signature: #{@request_signature}"
# The request signature is based on any file attached, if any. Otherwise
# it's based on the body of the request.
# TODO: tim: 2009-12-28: It'd be nice to remove this special case, and
# always hash the entire request body. In the file case it would just be
# expanded multipart text - the entire body of the POST.
#
# Pull out any file that was attached to this request, using multipart
# form uploads.
# Depending on the server we're running in, multipart form uploads are
# handed to us differently.
# - In Passenger (Cookbooks Community Site), the File is handed to us
# directly in the params hash. The name is whatever the client used,
# its value is therefore a File or Tempfile.
# e.g. request['file_param'] = File
#
# - In Merb (Chef server), the File is wrapped. The original parameter
# name used for the file is used, but its value is a Hash. Within
# the hash is a name/value pair named 'file' which actually
# contains the Tempfile instance.
# e.g. request['file_param'] = { :file => Tempfile }
file_param = request.params.values.find { |value| value.respond_to?(:read) }
# No file_param; we're running in Merb, or it's just not there..
if file_param.nil?
hash_param = request.params.values.find { |value| value.respond_to?(:has_key?) } # Hash responds to :has_key? .
if !hash_param.nil?
file_param = hash_param.values.find { |value| value.respond_to?(:read) } # File/Tempfile responds to :read.
end
end
# Any file that's included in the request is hashed if it's there. Otherwise,
# we hash the body.
if file_param
Mixlib::Authentication::Log.debug "Digesting file_param: '#{file_param.inspect}'"
@hashed_body = digester.hash_file(file_param)
else
body = request.raw_post
Mixlib::Authentication::Log.debug "Digesting body: '#{body}'"
@hashed_body = digester.hash_body(body)
end
Mixlib::Authentication::Log.debug "Authenticating user : #{user_id}, User secret is : #{@user_secret}, Request signature is :\n#{@request_signature}, Hashed Body is : #{@hashed_body}"
#BUGBUG Not doing anything with the signing description yet [cb]
parse_signing_description
candidate_block = canonicalize_request
request_decrypted_block = @user_secret.public_decrypt(Base64.decode64(@request_signature))
signatures_match = (request_decrypted_block == candidate_block)
timeskew_is_acceptable = timestamp_within_bounds?(Time.parse(timestamp), Time.now)
hashes_match = @content_hash == hashed_body
rescue StandardError=>se
raise StandardError,"Failed to authenticate user request. Most likely missing a necessary header: #{se.message}", se.backtrace
end
Mixlib::Authentication::Log.debug "Candidate Block is: '#{candidate_block}'\nRequest decrypted block is: '#{request_decrypted_block}'\nCandidate content hash is: #{hashed_body}\nRequest Content Hash is: '#{@content_hash}'\nSignatures match: #{signatures_match}, Allowed Time Skew: #{timeskew_is_acceptable}, Hashes match?: #{hashes_match}\n"
if signatures_match and timeskew_is_acceptable and hashes_match
OpenStruct.new(:name=>user_id)
else
nil
end
end
private
# Compare the request timestamp with boundary time
#
#
# ====Parameters
# time1<Time>:: minuend
# time2<Time>:: subtrahend
#
def timestamp_within_bounds?(time1, time2)
time_diff = (time2-time1).abs
is_allowed = (time_diff < @allowed_time_skew)
Mixlib::Authentication::Log.debug "Request time difference: #{time_diff}, within #{@allowed_time_skew} seconds? : #{!!is_allowed}"
is_allowed
end
end
end
end
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