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From 2a6b3b5afb20a7856ad81b3ec3da621571c3bec3 Mon Sep 17 00:00:00 2001
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From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
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Date: Wed, 20 Oct 2021 10:41:36 +0200
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Subject: [PATCH] cc_ssh.py: fix private key group owner and permissions
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 (#1070)
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RH-Author: Emanuele Giuseppe Esposito <eesposit@redhat.com>
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RH-MergeRequest: 12: cc_ssh.py: fix private key group owner and permissions (#1070)
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RH-Commit: [1/1] b2dc9cfd18ac0a8e1e22a37b1585d22dbde11536 (eesposit/cloud-init-centos-)
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RH-Bugzilla: 2015974
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RH-Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>
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RH-Acked-by: Mohamed Gamal Morsy <mmorsy@redhat.com>
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commit ee296ced9c0a61b1484d850b807c601bcd670ec1
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Author: Emanuele Giuseppe Esposito <eesposit@redhat.com>
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Date:   Tue Oct 19 21:32:10 2021 +0200
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    cc_ssh.py: fix private key group owner and permissions (#1070)
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    When default host keys are created by sshd-keygen (/etc/ssh/ssh_host_*_key)
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    in RHEL/CentOS/Fedora, openssh it performs the following:
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    // create new keys
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    if ! $KEYGEN -q -t $KEYTYPE -f $KEY -C '' -N '' >&/dev/null; then
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            exit 1
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    fi
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    // sanitize permissions
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    /usr/bin/chgrp ssh_keys $KEY
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    /usr/bin/chmod 640 $KEY
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    /usr/bin/chmod 644 $KEY.pub
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    Note that the group ssh_keys exists only in RHEL/CentOS/Fedora.
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    Now that we disable sshd-keygen to allow only cloud-init to create
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    them, we miss the "sanitize permissions" part, where we set the group
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    owner as ssh_keys and the private key mode to 640.
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    According to https://bugzilla.redhat.com/show_bug.cgi?id=2013644#c8, failing
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    to set group ownership and permissions like openssh does makes the RHEL openscap
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    tool generate an error.
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    Signed-off-by: Emanuele Giuseppe Esposito eesposit@redhat.com
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    RHBZ: 2013644
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Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
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---
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 cloudinit/config/cc_ssh.py |  7 +++++++
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 cloudinit/util.py          | 14 ++++++++++++++
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 2 files changed, 21 insertions(+)
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diff --git a/cloudinit/config/cc_ssh.py b/cloudinit/config/cc_ssh.py
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index 05a16dbc..4e986c55 100755
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--- a/cloudinit/config/cc_ssh.py
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+++ b/cloudinit/config/cc_ssh.py
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@@ -240,6 +240,13 @@ def handle(_name, cfg, cloud, log, _args):
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                 try:
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                     out, err = subp.subp(cmd, capture=True, env=lang_c)
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                     sys.stdout.write(util.decode_binary(out))
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+
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+                    gid = util.get_group_id("ssh_keys")
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+                    if gid != -1:
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+                        # perform same "sanitize permissions" as sshd-keygen
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+                        os.chown(keyfile, -1, gid)
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+                        os.chmod(keyfile, 0o640)
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+                        os.chmod(keyfile + ".pub", 0o644)
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                 except subp.ProcessExecutionError as e:
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                     err = util.decode_binary(e.stderr).lower()
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                     if (e.exit_code == 1 and
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diff --git a/cloudinit/util.py b/cloudinit/util.py
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index 343976ad..fe37ae89 100644
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--- a/cloudinit/util.py
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+++ b/cloudinit/util.py
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@@ -1831,6 +1831,20 @@ def chmod(path, mode):
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             os.chmod(path, real_mode)
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+def get_group_id(grp_name: str) -> int:
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+    """
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+    Returns the group id of a group name, or -1 if no group exists
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+
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+    @param grp_name: the name of the group
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+    """
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+    gid = -1
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+    try:
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+        gid = grp.getgrnam(grp_name).gr_gid
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+    except KeyError:
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+        LOG.debug("Group %s is not a valid group name", grp_name)
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+    return gid
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+
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+
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 def get_permissions(path: str) -> int:
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     """
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     Returns the octal permissions of the file/folder pointed by the path,
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-- 
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2.27.0
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