[PATCH v8 2/3] Teach SELinux about anonymous inodes

[Stephen Smalley]

On Thu, Aug 27, 2020 at 2:35 AM Lokesh Gidra <lokeshgidra at google.com> wrote:
>
> From: Daniel Colascione <dancol at google.com>
>
> This change uses the anon_inodes and LSM infrastructure introduced in
> the previous patch to give SELinux the ability to control
> anonymous-inode files that are created using the new anon_inode_getfd_secure()
> function.
>
> A SELinux policy author detects and controls these anonymous inodes by
> adding a name-based type_transition rule that assigns a new security
> type to anonymous-inode files created in some domain. The name used
> for the name-based transition is the name associated with the
> anonymous inode for file listings --- e.g., "[userfaultfd]" or
> "[perf_event]".
>
> Example:
>
> type uffd_t;
> type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]";
> allow sysadm_t uffd_t:anon_inode { create };
>
> (The next patch in this series is necessary for making userfaultfd
> support this new interface.  The example above is just
> for exposition.)
>
> Signed-off-by: Daniel Colascione <dancol at google.com>
> Acked-by: Casey Schaufler <casey at schaufler-ca.com>
> Acked-by: Stephen Smalley <stephen.smalley.work at gmail.com>
> Cc: Al Viro <viro at zeniv.linux.org.uk>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> ---
>  security/selinux/hooks.c            | 53 +++++++++++++++++++++++++++++
>  security/selinux/include/classmap.h |  2 ++
>  2 files changed, 55 insertions(+)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index a340986aa92e..b83f56e5ef40 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2926,6 +2926,58 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
>         return 0;
>  }
>
> +static int selinux_inode_init_security_anon(struct inode *inode,
> +                                           const struct qstr *name,
> +                                           const struct inode *context_inode)
> +{
> +       const struct task_security_struct *tsec = selinux_cred(current_cred());
> +       struct common_audit_data ad;
> +       struct inode_security_struct *isec;
> +       int rc;
> +
> +       if (unlikely(!selinux_state.initialized))

This should use selinux_initialized(&selinux_state) instead.