1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
require_relative 'openssl'
##
# S3URISigner implements AWS SigV4 for S3 Source to avoid a dependency on the aws-sdk-* gems
# More on AWS SigV4: https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
class Gem::S3URISigner
class ConfigurationError < Gem::Exception
def initialize(message)
super message
end
def to_s # :nodoc:
"#{super}"
end
end
class InstanceProfileError < Gem::Exception
def initialize(message)
super message
end
def to_s # :nodoc:
"#{super}"
end
end
attr_accessor :uri
def initialize(uri)
@uri = uri
end
##
# Signs S3 URI using query-params according to the reference: https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
def sign(expiration = 86400)
s3_config = fetch_s3_config
current_time = Time.now.utc
date_time = current_time.strftime("%Y%m%dT%H%m%SZ")
date = date_time[0,8]
credential_info = "#{date}/#{s3_config.region}/s3/aws4_request"
canonical_host = "#{uri.host}.s3.#{s3_config.region}.amazonaws.com"
query_params = generate_canonical_query_params(s3_config, date_time, credential_info, expiration)
canonical_request = generate_canonical_request(canonical_host, query_params)
string_to_sign = generate_string_to_sign(date_time, credential_info, canonical_request)
signature = generate_signature(s3_config, date, string_to_sign)
URI.parse("https://#{canonical_host}#{uri.path}?#{query_params}&X-Amz-Signature=#{signature}")
end
private
S3Config = Struct.new :access_key_id, :secret_access_key, :security_token, :region
def generate_canonical_query_params(s3_config, date_time, credential_info, expiration)
canonical_params = {}
canonical_params["X-Amz-Algorithm"] = "AWS4-HMAC-SHA256"
canonical_params["X-Amz-Credential"] = "#{s3_config.access_key_id}/#{credential_info}"
canonical_params["X-Amz-Date"] = date_time
canonical_params["X-Amz-Expires"] = expiration.to_s
canonical_params["X-Amz-SignedHeaders"] = "host"
canonical_params["X-Amz-Security-Token"] = s3_config.security_token if s3_config.security_token
# Sorting is required to generate proper signature
canonical_params.sort.to_h.map do |key, value|
"#{base64_uri_escape(key)}=#{base64_uri_escape(value)}"
end.join("&")
end
def generate_canonical_request(canonical_host, query_params)
[
"GET",
uri.path,
query_params,
"host:#{canonical_host}",
"", # empty params
"host",
"UNSIGNED-PAYLOAD",
].join("\n")
end
def generate_string_to_sign(date_time, credential_info, canonical_request)
[
"AWS4-HMAC-SHA256",
date_time,
credential_info,
OpenSSL::Digest::SHA256.hexdigest(canonical_request),
].join("\n")
end
def generate_signature(s3_config, date, string_to_sign)
date_key = OpenSSL::HMAC.digest("sha256", "AWS4" + s3_config.secret_access_key, date)
date_region_key = OpenSSL::HMAC.digest("sha256", date_key, s3_config.region)
date_region_service_key = OpenSSL::HMAC.digest("sha256", date_region_key, "s3")
signing_key = OpenSSL::HMAC.digest("sha256", date_region_service_key, "aws4_request")
OpenSSL::HMAC.hexdigest("sha256", signing_key, string_to_sign)
end
##
# Extracts S3 configuration for S3 bucket
def fetch_s3_config
return S3Config.new(uri.user, uri.password, nil, "us-east-1") if uri.user && uri.password
s3_source = Gem.configuration[:s3_source] || Gem.configuration["s3_source"]
host = uri.host
raise ConfigurationError.new("no s3_source key exists in .gemrc") unless s3_source
auth = s3_source[host] || s3_source[host.to_sym]
raise ConfigurationError.new("no key for host #{host} in s3_source in .gemrc") unless auth
provider = auth[:provider] || auth["provider"]
case provider
when "env"
id = ENV["AWS_ACCESS_KEY_ID"]
secret = ENV["AWS_SECRET_ACCESS_KEY"]
security_token = ENV["AWS_SESSION_TOKEN"]
when "instance_profile"
credentials = ec2_metadata_credentials_json
id = credentials["AccessKeyId"]
secret = credentials["SecretAccessKey"]
security_token = credentials["Token"]
else
id = auth[:id] || auth["id"]
secret = auth[:secret] || auth["secret"]
security_token = auth[:security_token] || auth["security_token"]
end
raise ConfigurationError.new("s3_source for #{host} missing id or secret") unless id && secret
region = auth[:region] || auth["region"] || "us-east-1"
S3Config.new(id, secret, security_token, region)
end
def base64_uri_escape(str)
str.gsub(/[\+\/=\n]/, BASE64_URI_TRANSLATE)
end
def ec2_metadata_credentials_json
require 'net/http'
require_relative 'request'
require_relative 'request/connection_pools'
require 'json'
iam_info = ec2_metadata_request(EC2_IAM_INFO)
# Expected format: arn:aws:iam::<id>:instance-profile/<role_name>
role_name = iam_info['InstanceProfileArn'].split('/').last
ec2_metadata_request(EC2_IAM_SECURITY_CREDENTIALS + role_name)
end
def ec2_metadata_request(url)
uri = URI(url)
@request_pool ||= create_request_pool(uri)
request = Gem::Request.new(uri, Net::HTTP::Get, nil, @request_pool)
response = request.fetch
case response
when Net::HTTPOK then
JSON.parse(response.body)
else
raise InstanceProfileError.new("Unable to fetch AWS metadata from #{uri}: #{response.message} #{response.code}")
end
end
def create_request_pool(uri)
proxy_uri = Gem::Request.proxy_uri(Gem::Request.get_proxy_from_env(uri.scheme))
certs = Gem::Request.get_cert_files
Gem::Request::ConnectionPools.new(proxy_uri, certs).pool_for(uri)
end
BASE64_URI_TRANSLATE = { "+" => "%2B", "/" => "%2F", "=" => "%3D", "\n" => "" }.freeze
EC2_IAM_INFO = "http://169.254.169.254/latest/meta-data/iam/info".freeze
EC2_IAM_SECURITY_CREDENTIALS = "http://169.254.169.254/latest/meta-data/iam/security-credentials/".freeze
end
|
