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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394
|
From: Zdenek Zambersky <zzambers@redhat.com>
Date: Thu, 6 May 2021 13:50:20 +0200
Subject: Added support for RSA client authentication with SHA-2
Source: https://github.com/net-ssh/net-ssh/pull/838
Backported-By: Antonio Terceiro <terceiro@debian.org>
---
lib/net/ssh/authentication/certificate.rb | 4 +-
lib/net/ssh/authentication/ed25519.rb | 2 +-
lib/net/ssh/authentication/key_manager.rb | 22 ++++++--
lib/net/ssh/authentication/methods/abstract.rb | 10 ++++
lib/net/ssh/authentication/methods/publickey.rb | 66 ++++++++++++++++++-----
lib/net/ssh/authentication/session.rb | 5 +-
lib/net/ssh/transport/openssl.rb | 16 ++++--
test/authentication/methods/test_publickey.rb | 71 ++++++++++++++++++++++---
test/authentication/test_session.rb | 6 ++-
9 files changed, 169 insertions(+), 33 deletions(-)
diff --git a/lib/net/ssh/authentication/certificate.rb b/lib/net/ssh/authentication/certificate.rb
index 82e37e9..95b01ff 100644
--- a/lib/net/ssh/authentication/certificate.rb
+++ b/lib/net/ssh/authentication/certificate.rb
@@ -65,8 +65,8 @@ module Net
).to_s
end
- def ssh_do_sign(data)
- key.ssh_do_sign(data)
+ def ssh_do_sign(data, sig_alg = nil)
+ key.ssh_do_sign(data, sig_alg)
end
def ssh_do_verify(sig, data)
diff --git a/lib/net/ssh/authentication/ed25519.rb b/lib/net/ssh/authentication/ed25519.rb
index 0c5530c..1989d1f 100644
--- a/lib/net/ssh/authentication/ed25519.rb
+++ b/lib/net/ssh/authentication/ed25519.rb
@@ -167,7 +167,7 @@ module Net
PubKey.new(@pk)
end
- def ssh_do_sign(data)
+ def ssh_do_sign(data, sig_alg = nil)
@sign_key.sign(data)
end
diff --git a/lib/net/ssh/authentication/key_manager.rb b/lib/net/ssh/authentication/key_manager.rb
index 242d5d5..3624550 100644
--- a/lib/net/ssh/authentication/key_manager.rb
+++ b/lib/net/ssh/authentication/key_manager.rb
@@ -159,7 +159,7 @@ module Net
# Regardless of the identity's origin or who does the signing, this
# will always return the signature in an SSH2-specified "signature
# blob" format.
- def sign(identity, data)
+ def sign(identity, data, sig_alg = nil)
info = known_identities[identity] or raise KeyManagerError, "the given identity is unknown to the key manager"
if info[:key].nil? && info[:from] == :file
@@ -171,13 +171,27 @@ module Net
end
if info[:key]
- return Net::SSH::Buffer.from(:string, identity.ssh_signature_type,
- :mstring, info[:key].ssh_do_sign(data.to_s)).to_s
+ if sig_alg.nil?
+ signed = info[:key].ssh_do_sign(data.to_s)
+ sig_alg = identity.ssh_signature_type
+ else
+ signed = info[:key].ssh_do_sign(data.to_s, sig_alg)
+ end
+ return Net::SSH::Buffer.from(:string, sig_alg,
+ :mstring, signed).to_s
end
if info[:from] == :agent
raise KeyManagerError, "the agent is no longer available" unless agent
- return agent.sign(info[:identity], data.to_s)
+
+ case sig_alg
+ when "rsa-sha2-512"
+ return agent.sign(info[:identity], data.to_s, Net::SSH::Authentication::Agent::SSH_AGENT_RSA_SHA2_512)
+ when "rsa-sha2-256"
+ return agent.sign(info[:identity], data.to_s, Net::SSH::Authentication::Agent::SSH_AGENT_RSA_SHA2_256)
+ else
+ return agent.sign(info[:identity], data.to_s)
+ end
end
raise KeyManagerError, "[BUG] can't determine identity origin (#{info.inspect})"
diff --git a/lib/net/ssh/authentication/methods/abstract.rb b/lib/net/ssh/authentication/methods/abstract.rb
index bcddd4f..8ec4d22 100644
--- a/lib/net/ssh/authentication/methods/abstract.rb
+++ b/lib/net/ssh/authentication/methods/abstract.rb
@@ -21,12 +21,22 @@ module Net
# this.
attr_reader :key_manager
+ # So far only affects algorithms used for rsa keys, but can be
+ # extended to other keys, e.g after reading of
+ # PubkeyAcceptedAlgorithms option from ssh_config file is implemented.
+ attr_reader :pubkey_algorithms
+
# Instantiates a new authentication method.
def initialize(session, options={})
@session = session
@key_manager = options[:key_manager]
@options = options
@prompt = options[:password_prompt]
+ @pubkey_algorithms = options[:pubkey_algorithms] \
+ || %w[rsa-sha2-256-cert-v01@openssh.com
+ ssh-rsa-cert-v01@openssh.com
+ rsa-sha2-256
+ ssh-rsa]
self.logger = session.logger
end
diff --git a/lib/net/ssh/authentication/methods/publickey.rb b/lib/net/ssh/authentication/methods/publickey.rb
index bff9ffd..7e9e422 100644
--- a/lib/net/ssh/authentication/methods/publickey.rb
+++ b/lib/net/ssh/authentication/methods/publickey.rb
@@ -27,41 +27,40 @@ module Net
# Builds a packet that contains the request formatted for sending
# a public-key request to the server.
- def build_request(pub_key, username, next_service, has_sig)
+ def build_request(pub_key, username, next_service, alg, has_sig)
blob = Net::SSH::Buffer.new
blob.write_key pub_key
userauth_request(username, next_service, "publickey", has_sig,
- pub_key.ssh_type, blob.to_s)
+ alg, blob.to_s)
end
# Builds and sends a request formatted for a public-key
# authentication request.
- def send_request(pub_key, username, next_service, signature=nil)
- msg = build_request(pub_key, username, next_service, !signature.nil?)
+ def send_request(pub_key, username, next_service, alg, signature = nil)
+ msg = build_request(pub_key, username, next_service, alg,
+ !signature.nil?)
msg.write_string(signature) if signature
send_message(msg)
end
- # Attempts to perform public-key authentication for the given
- # username, with the given identity (public key). Returns +true+ if
- # successful, or +false+ otherwise.
- def authenticate_with(identity, next_service, username)
+ def authenticate_with_alg(identity, next_service, username, alg, sig_alg = nil)
debug { "trying publickey (#{identity.fingerprint})" }
- send_request(identity, username, next_service)
+ send_request(identity, username, next_service, alg)
message = session.next_message
case message.type
when USERAUTH_PK_OK
- buffer = build_request(identity, username, next_service, true)
+ buffer = build_request(identity, username, next_service, alg,
+ true)
sig_data = Net::SSH::Buffer.new
sig_data.write_string(session_id)
sig_data.append(buffer.to_s)
- sig_blob = key_manager.sign(identity, sig_data)
+ sig_blob = key_manager.sign(identity, sig_data, sig_alg)
- send_request(identity, username, next_service, sig_blob.to_s)
+ send_request(identity, username, next_service, alg, sig_blob.to_s)
message = session.next_message
case message.type
@@ -89,6 +88,49 @@ module Net
raise Net::SSH::Exception, "unexpected reply to USERAUTH_REQUEST: #{message.type} (#{message.inspect})"
end
end
+
+ # Attempts to perform public-key authentication for the given
+ # username, with the given identity (public key). Returns +true+ if
+ # successful, or +false+ otherwise.
+ def authenticate_with(identity, next_service, username)
+ type = identity.ssh_type
+ if type == "ssh-rsa"
+ pubkey_algorithms.each do |pk_alg|
+ case pk_alg
+ when "rsa-sha2-512", "rsa-sha2-256", "ssh-rsa"
+ if authenticate_with_alg(identity, next_service, username, pk_alg, pk_alg)
+ # success
+ return true
+ end
+ end
+ end
+ elsif type == "ssh-rsa-cert-v01@openssh.com"
+ pubkey_algorithms.each do |pk_alg|
+ case pk_alg
+ when "rsa-sha2-512-cert-v01@openssh.com"
+ if authenticate_with_alg(identity, next_service, username, pk_alg, "rsa-sha2-512")
+ # success
+ return true
+ end
+ when "rsa-sha2-256-cert-v01@openssh.com"
+ if authenticate_with_alg(identity, next_service, username, pk_alg, "rsa-sha2-256")
+ # success
+ return true
+ end
+ when "ssh-rsa-cert-v01@openssh.com"
+ if authenticate_with_alg(identity, next_service, username, pk_alg)
+ # success
+ return true
+ end
+ end
+ end
+ elsif authenticate_with_alg(identity, next_service, username, type)
+ # success
+ return true
+ end
+ # failure
+ return false
+ end
end
end
diff --git a/lib/net/ssh/authentication/session.rb b/lib/net/ssh/authentication/session.rb
index dfc5c06..a524c52 100644
--- a/lib/net/ssh/authentication/session.rb
+++ b/lib/net/ssh/authentication/session.rb
@@ -77,7 +77,10 @@ module Net
debug { "trying #{name}" }
begin
auth_class = Methods.const_get(name.split(/\W+/).map { |p| p.capitalize }.join)
- method = auth_class.new(self, key_manager: key_manager, password_prompt: options[:password_prompt])
+ method = auth_class.new(self,
+ key_manager: key_manager, password_prompt: options[:password_prompt],
+ pubkey_algorithms: options[:pubkey_algorithms] || nil)
+
rescue NameError
debug {"Mechanism #{name} was requested, but isn't a known type. Ignoring it."}
next
diff --git a/lib/net/ssh/transport/openssl.rb b/lib/net/ssh/transport/openssl.rb
index d2d7117..3f10b02 100644
--- a/lib/net/ssh/transport/openssl.rb
+++ b/lib/net/ssh/transport/openssl.rb
@@ -68,8 +68,16 @@ module OpenSSL
end
# Returns the signature for the given data.
- def ssh_do_sign(data)
- sign(OpenSSL::Digest::SHA1.new, data)
+ def ssh_do_sign(data, sig_alg = nil)
+ digester =
+ if sig_alg == "rsa-sha2-512"
+ OpenSSL::Digest::SHA512.new
+ elsif sig_alg == "rsa-sha2-256"
+ OpenSSL::Digest::SHA256.new
+ else
+ OpenSSL::Digest::SHA1.new
+ end
+ sign(digester, data)
end
end
@@ -105,7 +113,7 @@ module OpenSSL
end
# Signs the given data.
- def ssh_do_sign(data)
+ def ssh_do_sign(data, sig_alg = nil)
sig = sign(OpenSSL::Digest::SHA1.new, data)
a1sig = OpenSSL::ASN1.decode(sig)
@@ -218,7 +226,7 @@ module OpenSSL
end
# Returns the signature for the given data.
- def ssh_do_sign(data)
+ def ssh_do_sign(data, sig_alg = nil)
digest = digester.digest(data)
sig = dsa_sign_asn1(digest)
a1sig = OpenSSL::ASN1.decode(sig)
diff --git a/test/authentication/methods/test_publickey.rb b/test/authentication/methods/test_publickey.rb
index 8f2cc73..05510f2 100644
--- a/test/authentication/methods/test_publickey.rb
+++ b/test/authentication/methods/test_publickey.rb
@@ -105,6 +105,50 @@ module Authentication
assert subject.authenticate("ssh-connection", "jamis")
end
+ def test_authenticate_rsa_sha2
+ key_manager.expects(:sign).with(&signature_parameters_with_alg(keys.first, "rsa-sha2-256")).returns("sig-one")
+
+ transport.expect do |t, packet|
+ assert_equal USERAUTH_REQUEST, packet.type
+ assert verify_userauth_request_packet(packet, keys.first, false, "rsa-sha2-256")
+ t.return(USERAUTH_PK_OK, :string, "rsa-sha2-256", :string, Net::SSH::Buffer.from(:key, keys.first))
+
+ t.expect do |t2, packet2|
+ assert_equal USERAUTH_REQUEST, packet2.type
+ assert verify_userauth_request_packet(packet2, keys.first, true, "rsa-sha2-256")
+ assert_equal "sig-one", packet2.read_string
+ t2.return(USERAUTH_SUCCESS)
+ end
+ end
+
+ assert subject(pubkey_algorithms: %w[rsa-sha2-256]).authenticate("ssh-connection", "jamis")
+ end
+
+ def test_authenticate_rsa_sha2_fallback
+ key_manager.expects(:sign).with(&signature_parameters(keys.first)).returns("sig-one")
+
+ transport.expect do |t, packet|
+ assert_equal USERAUTH_REQUEST, packet.type
+ assert verify_userauth_request_packet(packet, keys.first, false, "rsa-sha2-256")
+ t.return(USERAUTH_FAILURE, :string, "publickey")
+
+ t.expect do |t2, packet2|
+ assert_equal USERAUTH_REQUEST, packet2.type
+ assert verify_userauth_request_packet(packet2, keys.first, false)
+ t2.return(USERAUTH_PK_OK, :string, keys.first.ssh_type, :string, Net::SSH::Buffer.from(:key, keys.first))
+
+ t2.expect do |t3, packet3|
+ assert_equal USERAUTH_REQUEST, packet3.type
+ assert verify_userauth_request_packet(packet3, keys.first, true)
+ assert_equal "sig-one", packet3.read_string
+ t3.return(USERAUTH_SUCCESS)
+ end
+ end
+ end
+
+ assert subject(pubkey_algorithms: %w[rsa-sha2-256 ssh-rsa]).authenticate("ssh-connection", "jamis")
+ end
+
private
def signature_parameters(key)
@@ -117,13 +161,25 @@ module Authentication
end
end
- def verify_userauth_request_packet(packet, key, has_sig)
- packet.read_string == "jamis" && # user-name
- packet.read_string == "ssh-connection" && # next service
- packet.read_string == "publickey" && # auth-method
- packet.read_bool == has_sig && # whether a signature is appended
- packet.read_string == key.ssh_type && # ssh key type
- packet.read_buffer.read_key.to_blob == key.to_blob # key
+ def signature_parameters_with_alg(key, alg)
+ Proc.new do |given_key, data, given_alg|
+ next false unless given_key.to_blob == key.to_blob
+ next false unless given_alg == alg
+
+ buffer = Net::SSH::Buffer.new(data)
+ buffer.read_string == "abcxyz123" && # session-id
+ buffer.read_byte == USERAUTH_REQUEST && # type
+ verify_userauth_request_packet(buffer, key, true, alg)
+ end
+ end
+
+ def verify_userauth_request_packet(packet, key, has_sig, alg = nil)
+ packet.read_string == "jamis" && # user-name
+ packet.read_string == "ssh-connection" && # next service
+ packet.read_string == "publickey" && # auth-method
+ packet.read_bool == has_sig && # whether a signature is appended
+ packet.read_string == (alg || key.ssh_type) && # ssh key type
+ packet.read_buffer.read_key.to_blob == key.to_blob # key
end
@@keys = nil
@@ -141,6 +197,7 @@ module Authentication
def subject(options={})
options[:key_manager] = key_manager(options) unless options.key?(:key_manager)
+ options[:pubkey_algorithms] = %w[ssh-rsa] unless options.key?(:pubkey_algorithms)
@subject ||= Net::SSH::Authentication::Methods::Publickey.new(session(options), options)
end
end
diff --git a/test/authentication/test_session.rb b/test/authentication/test_session.rb
index db37467..19b9f8a 100644
--- a/test/authentication/test_session.rb
+++ b/test/authentication/test_session.rb
@@ -168,8 +168,10 @@ module Authentication
private
- def session(options={})
- @session ||= Net::SSH::Authentication::Session.new(transport(options), options)
+ def session(options = {})
+ session_opts = options.clone
+ session_opts[:pubkey_algorithms] = %w[ssh-rsa]
+ @session ||= Net::SSH::Authentication::Session.new(transport(options), session_opts)
end
def transport(options={})
|