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

From: Daniel Colascione <redacted>

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 <redacted>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@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))