Kernel commit 3ba4bf5f1e2c ("selinux: add a map permission check for
mmap") added a map permission check on mmap so that we can
distinguish memory mapped access (since it has different implications
for revocation).  The purpose of a separate map permission check on
mmap(2) is to permit policy to prohibit memory mapping of specific
files for which we need to ensure that every access is revalidated,
particularly useful for scenarios where we expect the file to be
relabeled at runtime in order to reflect state changes (e.g.
cross-domain solution, assured pipeline without data copying).

system/sepolicy commit 4397f082 added
the map permission to common file macros, to ensure that file access
would continue working even in the presence of a newer kernel. However,
that change did not affect socket access.

Certain socket classes, such as AF_NETLINK and AF_PACKET, also support
mmap operations. This change adds the map permission to rw_socket_perms,
to ensure continued support for newer kernels.

This technically allows mmap even in cases where the socket family
doesn't support it (such as TCP and UDP sockets), but granting it
is harmless in those cases.

In particular, this fixes a bug in clatd, where the following error
would occur:

  10-01 13:59:03.182 7129 7129 I clatd : Starting clat version 1.4 on rmnet0 netid=100 mark=0xf0064
  10-01 13:59:03.195 7129 7129 I auditd : type=1400 audit(0.0:18): avc: denied { map } for comm="clatd" path="socket:[52802]" dev="sockfs" ino=52802 scontext=u:r:clatd:s0 tcontext=u:r:clatd:s0 tclass=packet_socket permissive=0
  10-01 13:59:03.195 7129 7129 W clatd : type=1400 audit(0.0:18): avc: denied { map } for path="socket:[52802]" dev="sockfs" ino=52802 scontext=u:r:clatd:s0 tcontext=u:r:clatd:s0 tclass=packet_socket permissive=0
  10-01 13:59:03.199 7129 7129 F clatd : mmap 1048576 failed: Permission denied

Test: policy compiles
Bug: 117791876
Change-Id: I39f286d577b4a2160037ef271517ae8a3839b49b