Modify create_file_perms and create_dir_perms so it doesn't have
the "link" permission. This permission controls whether hard links
are allowed or not on the given file label. Hard links are a common
source of security bugs, and isn't something we want to support by
default.
Get rid of link_file_perms and move the necessary permissions into
create_file_perms and create_dir_perms. Nobody is using this macro,
so it's pointless to keep it around.
Get rid of unlink on directories. It returns EISDIR if you attempt to
do it, independent of SELinux permissions.
SELinux domains which have a need for hard linking for a particular
file type can add it back to their permission set on an as-needed basis.
Add a compile time assertion (neverallow rule) for untrusted_app.
It's particularly dangerous for untrusted_app to ever have hard
link capabilities, and the neverallow rule will prevent regressions.
Bug: 19953790
Change-Id: I5e9493d2bf5da460d074f0bc5ad8ba7c14dec6e0
There is some overlap between socket rules in app.te and the net.te rules,
but they aren't quite identical since not all app domains presently include
the net_domain() macro and because the rules in app.te allow more permissions
for netlink_route_socket and allow rawip_socket permissions for ping.
The current app.te rules prevent one from ever creating a non-networked app
domain. Resolve this overlap by:
1) Adding the missing permissions allowed by app.te to net.te for
netlink_route_socket and rawip_socket.
2) Adding net_domain() calls to all existing app domains that do not already
have it.
3) Deleting the redundant socket rules from app.te.
Then we'll have no effective change in what is allowed for apps but
allow one to define app domains in the future that are not allowed
network access.
Also cleanup net.te to use the create_socket_perms macro rather than *
and add macros for stream socket permissions.
Change-Id: I6e80d65b0ccbd48bd2b7272c083a4473e2b588a9
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
