Motivation for this change

Fixes a bunch of CVEs. The version identifiers in the CVE descriptions are not always correct, I validated all CVEs against the source tree.

• CVE-2020-10684
  • A flaw was found in Ansible Engine, all versions 2.7.x, 2.8.x and 2.9.x prior to 2.7.17, 2.8.9 and 2.9.6 respectively, when using ansible_facts as a subkey of itself and promoting it to a variable when inject is enabled, overwriting the ansible_facts after the clean. An attacker could take advantage of this by altering the ansible_facts, such as ansible_hosts, users and any other key data which would lead into privilege escalation or code injection.
• CVE-2020-1733
  • A race condition flaw was found in Ansible Engine 2.7.17 and prior, 2.8.9 and prior, 2.9.6 and prior when running a playbook with an unprivileged become user. When Ansible needs to run a module with become user, the temporary directory is created in /var/tmp. This directory is created with "umask 77 && mkdir -p "; this operation does not fail if the directory already exists and is owned by another user. An attacker could take advantage to gain control of the become user as the target directory can be retrieved by iterating '/proc//cmdline'.
• CVE-2020-1735
  • A flaw was found in the Ansible Engine when the fetch module is used. An attacker could intercept the module, inject a new path, and then choose a new destination path on the controller node. All versions in 2.7.x, 2.8.x and 2.9.x branches are believed to be vulnerable.
• CVE-2020-1739
  • A flaw was found in Ansible 2.7.16 and prior, 2.8.8 and prior, and 2.9.5 and prior when a password is set with the argument "password" of svn module, it is used on svn command line, disclosing to other users within the same node. An attacker could take advantage by reading the cmdline file from that particular PID on the procfs.
• CVE-2020-1740
  • A flaw was found in Ansible Engine when using Ansible Vault for editing encrypted files. When a user executes "ansible-vault edit", another user on the same computer can read the old and new secret, as it is created in a temporary file with mkstemp and the returned file descriptor is closed and the method write_data is called to write the existing secret in the file. This method will delete the file before recreating it insecurely. All versions in 2.7.x, 2.8.x and 2.9.x branches are believed to be vulnerable.
     

The following CVEs are yet to be fixed:

• CVE-2020-1736 (unfixed The default permissions used by atomic_move can create files that are world readable  ansible/ansible#67794)
  • A flaw was found in Ansible Engine when a file is moved using atomic_move primitive as the file mode cannot be specified. This sets the destination files world-readable if the destination file does not exist and if the file exists, the file could be changed to have less restrictive permissions before the move. This could lead to the disclosure of sensitive data. All versions in 2.7.x, 2.8.x and 2.9.x branches are believed to be vulnerable.
• CVE-2020-1738 (unfixed, unimportant, requires remote to be compromised already package and service modules allow arbitrary modules to be executed  ansible/ansible#67796 (comment))
  • A flaw was found in Ansible Engine when the module package or service is used and the parameter 'use' is not specified. If a previous task is executed with a malicious user, the module sent can be selected by the attacker using the ansible facts file. All versions in 2.7.x, 2.8.x and 2.9.x branches are believed to be vulnerable.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.