[refpolicy] Simplifying user content: Concept.

[domg472@gmail.com (Dominick Grift)]

I would like your opinion on the following concept ( i actually have
this implemented in my branch ).

Making user content easier:

1. Three new attributes: user_home_type, user_tmp_type, user_tmpfs_type
in the user domain. (fedora already had user_home_type)

2. Modify userdom_user_home_content()
   - Attach user_home_type to userdom_user_home_content()
   - Make userdom_user_home_content files_poly_member()

3. Create userdom_?ser_tmp_content()
   - is files_tmp_file()
   - Attach user_tmp_type to userdom_user_tmp_content()
   - Make userdom_user_tmp_content() files_poly_member_tmp()

4. Modify userdom_manage_{home,tmp,tmpfs}roles
   - allow caller (userdomain) to manage and relabel
user_{home,tmp,tmpfs}_type

5. Replace where possible in userdomain; user_home_t, user_tmp_t,
user_tmpfs_t declarations:
   - userdom_user_home_content(user_home_t)
   - userdom_user_tmp_content(userdomain, user_tmp_t)
   - userdom_user_tmp_fs_content(user_tmpfs_t

6. Replace all "user" tmp and tmpfs content declarations in apps and
other modules.

Impact:

1. Simply use userdom_user_tmp_content(type) instead of
files_tmp_file(type)
files_poly_member_tmp(domain, type)
ubac_constrained(type)

or userdom_user_home_content(type) instead of
userdom_user_home_content(type)
files_poly_member(type)

or userdom_user_tmpfs_content(type) instead of
files_tmpfs_file(type)
ubac_constrained(type)

2. By attaching the declared "type" attributes to the various classes of
user content we can simplify how users can interact with this content.
User domains should be able to manage and relabel *any* user content
either owned by the user or by an user app or even system server. After
all: its user content.

3. Since only user domains should call the
userdom_manage_{home,tmp,tmpfs}_role templates we can allow the caller
permission to manage and relabel user_home_types, user_tmp_types and
user_tmpfs_types.

This way we no longer have to implicitly define policy that allows users
to interact with user content.

If the user has access to the userdom_manage_{home, tmp, tmpfs}_role
template, and if the content is declared userdom_user_{home, tmp,
tmpfs}_content, then users can automatically fully control it.

This saves a heap of policy writing.

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