ansible-test - Support RSA SHA-1 for SSH clients.

changelogs/fragments/ansible-test-container-management.yml

@@ -39,6 +39,11 @@ minor_changes:
                    adding the ``retry/never`` alias. This is useful for tests that cannot pass on a retry or are too
                    slow to make retries useful.
   - ansible-test - The ``ansible-test env`` command now detects and reports the container ID if running in a container.
+  - ansible-test - SSH connections from OpenSSH 8.8+ to CentOS 6 containers now work without additional configuration.
+                   However, clients older than OpenSSH 7.0 can no longer connect to CentOS 6 containers as a result.
+                   The container must have ``centos6`` in the image name for this work-around to be applied.
+  - ansible-test - SSH shell connections from OpenSSH 8.8+ to ansible-test provisioned network instances now work without additional configuration.
+                   However, clients older than OpenSSH 7.0 can no longer open shell sessions for ansible-test provisioned network instances as a result.
 bugfixes:
   - ansible-test - Multiple containers now work under Podman without specifying the ``--docker-network`` option.
   - ansible-test - Prevent concurrent / repeat pulls of the same container image.

test/lib/ansible_test/_internal/connections.py

@@ -34,6 +34,7 @@ from .docker_util import (
 
 from .ssh import (
     SshConnectionDetail,
+    ssh_options_to_list,
 )
 
 from .become import (
@@ -123,7 +124,7 @@ class SshConnection(Connection):
 
         self.options = ['-i', settings.identity_file]
 
-        ssh_options = dict(
+        ssh_options: dict[str, t.Union[int, str]] = dict(
             BatchMode='yes',
             StrictHostKeyChecking='no',
             UserKnownHostsFile='/dev/null',
@@ -131,8 +132,9 @@ class SshConnection(Connection):
             ServerAliveCountMax=4,
         )
 
-        for ssh_option in sorted(ssh_options):
-            self.options.extend(['-o', f'{ssh_option}={ssh_options[ssh_option]}'])
+        ssh_options.update(settings.options)
+
+        self.options.extend(ssh_options_to_list(ssh_options))
 
     def run(self,
             command: list[str],

test/lib/ansible_test/_internal/host_profiles.py

@@ -998,6 +998,10 @@ class DockerProfile(ControllerHostProfile[DockerConfig], SshTargetHostProfile[Do
             port=port,
             identity_file=SshKey(self.args).key,
             python_interpreter=self.python.path,
+            # CentOS 6 uses OpenSSH 5.3, making it incompatible with the default configuration of OpenSSH 8.8 and later clients.
+            # Since only CentOS 6 is affected, and it is only supported by ansible-core 2.12, support for RSA SHA-1 is simply hard-coded here.
+            # A substring is used to allow custom containers to work, not just the one provided with ansible-test.
+            enable_rsa_sha1='centos6' in self.config.image,
         )
 
         return [SshConnection(self.args, settings)]
@@ -1089,6 +1093,12 @@ class NetworkRemoteProfile(RemoteProfile[NetworkRemoteConfig]):
             ansible_port=connection.port,
             ansible_user=connection.username,
             ansible_ssh_private_key_file=core_ci.ssh_key.key,
+            # VyOS 1.1.8 uses OpenSSH 5.5, making it incompatible with RSA SHA-256/512 used by Paramiko 2.9 and later.
+            # IOS CSR 1000V uses an ancient SSH server, making it incompatible with RSA SHA-256/512 used by Paramiko 2.9 and later.
+            # That means all network platforms currently offered by ansible-core-ci require support for RSA SHA-1, so it is simply hard-coded here.
+            # NOTE: This option only exists in ansible-core 2.14 and later. For older ansible-core versions, use of Paramiko 2.8.x or earlier is required.
+            #       See: https://github.com/ansible/ansible/pull/78789
+            #       See: https://github.com/ansible/ansible/pull/78842
             ansible_paramiko_use_rsa_sha2_algorithms='no',
             ansible_network_os=f'{self.config.collection}.{self.config.platform}' if self.config.collection else self.config.platform,
         )
@@ -1132,6 +1142,10 @@ class NetworkRemoteProfile(RemoteProfile[NetworkRemoteConfig]):
             port=core_ci.connection.port,
             user=core_ci.connection.username,
             identity_file=core_ci.ssh_key.key,
+            # VyOS 1.1.8 uses OpenSSH 5.5, making it incompatible with the default configuration of OpenSSH 8.8 and later clients.
+            # IOS CSR 1000V uses an ancient SSH server, making it incompatible with the default configuration of OpenSSH 8.8 and later clients.
+            # That means all network platforms currently offered by ansible-core-ci require support for RSA SHA-1, so it is simply hard-coded here.
+            enable_rsa_sha1=True,
         )
 
         return [SshConnection(self.args, settings)]

test/lib/ansible_test/_internal/inventory.py

@@ -25,6 +25,10 @@ from .host_profiles import (
     WindowsRemoteProfile,
 )
 
+from .ssh import (
+    ssh_options_to_str,
+)
+
 
 def create_controller_inventory(args: EnvironmentConfig, path: str, controller_host: ControllerHostProfile) -> None:
     """Create and return inventory for use in controller-only integration tests."""
@@ -149,6 +153,7 @@ def create_posix_inventory(args: EnvironmentConfig, path: str, target_hosts: lis
             ansible_port=ssh.settings.port,
             ansible_user=ssh.settings.user,
             ansible_ssh_private_key_file=ssh.settings.identity_file,
+            ansible_ssh_extra_args=ssh_options_to_str(ssh.settings.options),
         )
 
         if ssh.become:

test/lib/ansible_test/_internal/ssh.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 import dataclasses
+import itertools
 import json
 import os
 import random
@@ -38,10 +39,40 @@ class SshConnectionDetail:
     identity_file: str
     python_interpreter: t.Optional[str] = None
     shell_type: t.Optional[str] = None
+    enable_rsa_sha1: bool = False
 
     def __post_init__(self):
         self.name = sanitize_host_name(self.name)
 
+    @property
+    def options(self) -> dict[str, str]:
+        """OpenSSH config options, which can be passed to the `ssh` CLI with the `-o` argument."""
+        options: dict[str, str] = {}
+
+        if self.enable_rsa_sha1:
+            # Newer OpenSSH clients connecting to older SSH servers must explicitly enable ssh-rsa support.
+            # OpenSSH 8.8, released on 2021-09-26, deprecated using RSA with the SHA-1 hash algorithm (ssh-rsa).
+            # OpenSSH 7.2, released on 2016-02-29, added support for using RSA with SHA-256/512 hash algorithms.
+            # See: https://www.openssh.com/txt/release-8.8
+            algorithms = '+ssh-rsa'  # append the algorithm to the default list, requires OpenSSH 7.0 or later
+
+            options.update(dict(
+                # Host key signature algorithms that the client wants to use.
+                # Available options can be found with `ssh -Q HostKeyAlgorithms` or `ssh -Q key` on older clients.
+                # This option was updated in OpenSSH 7.0, released on 2015-08-11, to support the "+" prefix.
+                # See: https://www.openssh.com/txt/release-7.0
+                HostKeyAlgorithms=algorithms,
+                # Signature algorithms that will be used for public key authentication.
+                # Available options can be found with `ssh -Q PubkeyAcceptedAlgorithms` or `ssh -Q key` on older clients.
+                # This option was added in OpenSSH 7.0, released on 2015-08-11.
+                # See: https://www.openssh.com/txt/release-7.0
+                # This option is an alias for PubkeyAcceptedAlgorithms, which was added in OpenSSH 8.5.
+                # See: https://www.openssh.com/txt/release-8.5
+                PubkeyAcceptedKeyTypes=algorithms,
+            ))
+
+        return options
+
 
 class SshProcess:
     """Wrapper around an SSH process."""
@@ -141,7 +172,7 @@ def create_ssh_command(
     if ssh.user:
         cmd.extend(['-l', ssh.user])  # user to log in as on the remote machine
 
-    ssh_options = dict(
+    ssh_options: dict[str, t.Union[int, str]] = dict(
         BatchMode='yes',
         ExitOnForwardFailure='yes',
         LogLevel='ERROR',
@@ -153,9 +184,7 @@ def create_ssh_command(
 
     ssh_options.update(options or {})
 
-    for key, value in sorted(ssh_options.items()):
-        cmd.extend(['-o', '='.join([key, str(value)])])
-
+    cmd.extend(ssh_options_to_list(ssh_options))
     cmd.extend(cli_args or [])
     cmd.append(ssh.host)
 
@@ -165,6 +194,18 @@ def create_ssh_command(
     return cmd
 
 
+def ssh_options_to_list(options: t.Union[dict[str, t.Union[int, str]], dict[str, str]]) -> list[str]:
+    """Format a dictionary of SSH options as a list suitable for passing to the `ssh` command."""
+    return list(itertools.chain.from_iterable(
+        ('-o', f'{key}={value}') for key, value in sorted(options.items())
+    ))
+
+
+def ssh_options_to_str(options: t.Union[dict[str, t.Union[int, str]], dict[str, str]]) -> str:
+    """Format a dictionary of SSH options as a string suitable for passing as `ansible_ssh_extra_args` in inventory."""
+    return shlex.join(ssh_options_to_list(options))
+
+
 def run_ssh_command(
         args: EnvironmentConfig,
         ssh: SshConnectionDetail,
@@ -245,7 +286,7 @@ def generate_ssh_inventory(ssh_connections: list[SshConnectionDetail]) -> str:
                 ansible_pipelining='yes',
                 ansible_python_interpreter=ssh.python_interpreter,
                 ansible_shell_type=ssh.shell_type,
-                ansible_ssh_extra_args='-o UserKnownHostsFile=/dev/null',  # avoid changing the test environment
+                ansible_ssh_extra_args=ssh_options_to_str(dict(UserKnownHostsFile='/dev/null', **ssh.options)),  # avoid changing the test environment
                 ansible_ssh_host_key_checking='no',
             ))) for ssh in ssh_connections),
         ),