add support for add/remove CA Certificates via cloud-config (LP: #915232)

LP: #915232

1 files changed, 88 insertions, 0 deletions

diff --git a/cloudinit/CloudConfig/cc_ca_certs.py b/cloudinit/CloudConfig/cc_ca_certs.py
new file mode 100644
index 00000000..c18821f9
--- /dev/null
+++ b/cloudinit/CloudConfig/cc_ca_certs.py
@@ -0,0 +1,88 @@
+# vi: ts=4 expandtab
+#
+#    Author: Mike Milner <mike.milner@canonical.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+import os
+from subprocess import check_call
+from cloudinit.util import (write_file, get_cfg_option_list_or_str,
+                            delete_dir_contents)
+
+CA_CERT_PATH = "/usr/share/ca-certificates/"
+CA_CERT_FILENAME = "cloud-init-ca-certs.crt"
+CA_CERT_CONFIG = "/etc/ca-certificates.conf"
+CA_CERT_SYSTEM_PATH = "/etc/ssl/certs/"
+
+
+def update_ca_certs():
+    """
+    Updates the CA certificate cache on the current machine.
+    """
+    check_call(["update-ca-certificates"])
+
+
+def add_ca_certs(certs):
+    """
+    Adds certificates to the system. To actually apply the new certificates
+    you must also call L{update_ca_certs}.
+
+    @param certs: A list of certificate strings.
+    """
+    if certs:
+        cert_file_contents = "\n".join(certs)
+        cert_file_fullpath = os.path.join(CA_CERT_PATH, CA_CERT_FILENAME)
+        write_file(cert_file_fullpath, cert_file_contents, mode=0644)
+        # Append cert filename to CA_CERT_CONFIG file.
+        write_file(CA_CERT_CONFIG, "\n%s" % CA_CERT_FILENAME, omode="a")
+
+
+def remove_default_ca_certs():
+    """
+    Removes all default trusted CA certificates from the system. To actually
+    apply the change you must also call L{update_ca_certs}.
+    """
+    delete_dir_contents(CA_CERT_PATH)
+    delete_dir_contents(CA_CERT_SYSTEM_PATH)
+    write_file(CA_CERT_CONFIG, "", mode=0644)
+
+
+def handle(_name, cfg, _cloud, log, _args):
+    """
+    Call to handle ca-cert sections in cloud-config file.
+
+    @param name: The module name "ca-cert" from cloud.cfg
+    @param cfg: A nested dict containing the entire cloud config contents.
+    @param cloud: The L{CloudInit} object in use.
+    @param log: Pre-initialized Python logger object to use for logging.
+    @param args: Any module arguments from cloud.cfg
+    """
+    # If there isn't a ca-certs section in the configuration don't do anything
+    if "ca-certs" not in cfg:
+        return
+    ca_cert_cfg = cfg['ca-certs']
+
+    # If there is a remove-defaults option set to true, remove the system
+    # default trusted CA certs first.
+    if ca_cert_cfg.get("remove-defaults", False):
+        log.debug("removing default certificates")
+        remove_default_ca_certs()
+
+    # If we are given any new trusted CA certs to add, add them.
+    if "trusted" in ca_cert_cfg:
+        trusted_certs = get_cfg_option_list_or_str(ca_cert_cfg, "trusted")
+        if trusted_certs:
+            log.debug("adding %d certificates" % len(trusted_certs))
+            add_ca_certs(trusted_certs)
+
+    # Update the system with the new cert configuration.
+    update_ca_certs()