VPP-899: Run VPP under SELinux

Add an SELinux profile such that VPP can run under SELinux on RPM based
platforms. The SELinux Policy is currently only implemented for RPM
packages, specifically, Fedora, CentOS and RHEL. Doxygen User
Documentation has been included (selinux_doc.md). Once some discussion
on file locations has completed (see vpp-devlist), updates to the Debug
CLI documentation will also need to be updated.

Additional changes:
Patch Set 2:
- Rework selinux_doc.md such that each line is only 80 characters
  instead of each sentence on a line. Made additonal minor chnages
  to the text.
- Update vHost Debug CLI documentation to reflex new socket location.
  Cleaned up some text from when I originally wrote it, to better
  reflex proper use.
- Update exec Debug CLI documentation to be more inline with suggested
  helptext, added text regarding recommended script file location.
- For Debian builds, create the /var/log/vpp/ directory. I don't use
  Debian very much, so please pay extra attention to
  build-data/platforms.mk and build-root/deb/debian/.gitignore.
- Per discussion on VPP call, changed the default log location to
  /var/log/vpp/vpp.log.
- Changed the socket location for vHost in AutoConfig to
  /var/run/vpp/.
Patch Set 3:
- Update selinux_doc.md based on comments.

Change-Id: I400520dc33f1ca51012d09ef8fe5a7b7b96c631e
Signed-off-by: Billy McFall <bmcfall@redhat.com>

1 files changed, 294 insertions, 0 deletions

diff --git a/extras/selinux/selinux_doc.md b/extras/selinux/selinux_doc.md
new file mode 100644
index 00000000000..e71bd658286
--- /dev/null
+++ b/extras/selinux/selinux_doc.md
@@ -0,0 +1,294 @@
+# SELinux - VPP Custom SELinux Policy    {#selinux_doc}
+
+## Overview
+
+Security-enhanced Linux (SELinux) is a security feature in the Linux kernel. At
+a very high level, SELinux implements mandatory access controls (MAC), as
+opposed to discretionary access control (DAC) implemented in standard Linux. MAC
+defines how processes can interact with other system components (Files,
+Directories, Other Processes, Pipes, Sockets, Network Ports). Each system
+component is assigned a label, and then the SELinux Policy defines which labels
+and which actions on each label a process is able to perform. The VPP Custom
+SELinux Policy defines the actions VPP is allowed to perform on which labels.
+
+The VPP Custom SELinux Policy is intended to be installed on RPM based platforms
+(tested on CentOS 7 and RHEL 7). Though SELinux can run on Debian platforms, it
+typically is not and therefore is not currently being built for Debian.
+
+The VPP Custom SELinux Policy does not enable or disable SELinux, only allows
+VPP to run when SELinux is enabled. A fresh install of either Fedora, CentOS or
+RHEL will have SELinux enabled by default. To determine if SELinux is enabled on
+a given system and enable it if needed, run:
+
+```
+   $ getenforce
+   Permissive
+
+   $ sudo setenforce 1
+
+   $ getenforce
+   Enforcing
+```
+
+To make the change persistent, modify the following file to set
+`SELINUX=enforcing`:
+
+```
+   $ sudo vi /etc/selinux/config
+   :
+   # This file controls the state of SELinux on the system.
+   # SELINUX= can take one of these three values:
+   #     enforcing - SELinux security policy is enforced.
+   #     permissive - SELinux prints warnings instead of enforcing.
+   #     disabled - No SELinux policy is loaded.
+   SELINUX=enforcing
+   :
+```
+
+## Installation
+
+To install VPP, see the installation instructions on the VPP Wiki
+(https://wiki.fd.io/view/VPP/Installing_VPP_binaries_from_packages). The VPP
+Custom SELinux Policy is packaged in its own RPM starting in 18.04,
+`vpp-selinux-policy-<VERSION>-<RELEASE>.rpm`. It is packaged and installed along
+with the other VPP RPMs.
+
+### Fresh Install of VPP
+
+If VPP has never been installed on a system, then starting in 18.04, the VPP
+Custom SELinux Policy will be installed with the other RPMs and all the system
+components managed by VPP will be labeled properly.
+
+### Fix SELinux Labels for VPP
+In the case where the VPP Custom Policy is being installed for the first time,
+either because VPP has been upgraded or packages were removed and then
+reinstalled, several directories and files will not not be properly labeled. The
+labels on these files will need to be fixed for VPP to run properly with SELinux
+enabled. After the VPP Custom SELinux Policy is installed, run the following
+commands to fix the labels. If VPP is already running, make sure to restart
+VPP after the labels are fixed. This change is persistent for the life of the
+file. Once the VPP Custom Policy is installed on the system, subsequent files
+created by VPP will be labeled properly. This is only to fix files created by
+VPP prior to the VPP Custom Policy being installed.
+
+```
+  $ sudo restorecon -Rv /etc/vpp/
+  $ sudo restorecon -Rv /usr/lib/vpp_api_test_plugins/
+  $ sudo restorecon -Rv /usr/lib/vpp_plugins/
+  $ sudo restorecon -Rv /usr/share/vpp/
+  $ sudo restorecon -Rv /var/run/vpp/
+
+  $ sudo chcon -t vpp_tmp_t /tmp/vpp_*
+  $ sudo chcon -t vpp_var_run_t /var/run/.vpp_*
+```
+
+**NOTE:** Because the VPP APIs allow custom filenames in certain scenarios, the
+above commands may not handle all files. Inspect your system and correct any
+files that are mislabeled. For example, to verify all VPP files in `/tmp/` are
+labeled properly, run:
+
+```
+  $ sudo ls -alZ /tmp/
+```
+
+Any files not properly labeled with `vpp_tmp_t`, run:
+
+```
+  $ sudo chcon -t vpp_tmp_t /tmp/<filename>
+```
+
+## VPP Files
+
+### Recommended Default File Directories
+
+Documentation in the VPP Wiki (https://wiki.fd.io/view/VPP/) and doxygen
+generated documentation have examples with files located in certain directories.
+Some of the recommend file locations have been moved to satisfy SELinux. Most of
+the documentation has been updated, but links to older documentation still exist
+and there may have been instances that were missed. Use the file locations
+described below to allow SELinux to properly label the given files.
+
+File locations that have changed:
+* VPP Debug CLI Script Files
+* vHost Sockets
+* VPP Log Files
+
+#### VPP Debug CLI Script Files
+
+The VPP Debug CLI, `vppctl`, allows a sequence of CLI commands to be read from a
+file and executed. To avoid from having to grant VPP access to all of `/tmp/` and
+possibly `/home/` sub-directories, it is recommended that any VPP Debug CLI script
+files be placed in a common directory such as `/usr/share/vpp/`.
+
+For example:
+```
+$ cat /usr/share/vpp/scripts/gigup.txt
+set interface state GigabitEthernet0/8/0 up
+set interface state GigabitEthernet0/9/0 up
+```
+
+To execute:
+```
+$ vppctl exec /usr/share/vpp/scripts/gigup.txt
+```
+Or
+```
+$ vppctl
+    _______    _        _   _____  ___
+ __/ __/ _ \  (_)__    | | / / _ \/ _ \
+ _/ _// // / / / _ \   | |/ / ___/ ___/
+ /_/ /____(_)_/\___/   |___/_/  /_/
+
+vpp# exec /usr/share/vpp/scripts/gigup.txt
+vpp# quit
+
+```
+
+If the file is not labeled properly, you will see something similar to:
+```
+$ vppctl exec /home/<user>/dev/vpp/scripts/vppctl/gigup.txt
+exec: failed to open `/home/<user>/dev/vpp/scripts/vppctl/gigup.txt': Permission denied
+
+$ ls -alZ
+drwxrwxr-x. <user> <user> unconfined_u:object_r:user_home_t:s0 .
+drwxrwxr-x. <user> <user> unconfined_u:object_r:user_home_t:s0 ..
+-rw-r--r--. <user> <user> unconfined_u:object_r:user_home_t:s0 gigup.txt
+```
+
+##### Original Documentation
+
+Some of the original documentation showed script files being executed out of
+`/tmp/`. Convenience also may lead to script files being placed in
+`/home/<user>/` subdirectories. If a file is generated by the VPP process in
+`/tmp/`, for example a trace file or pcap file, it will get properly labeled
+with the SELinux label `vpp_tmp_t`. When a file is created, unless a rule is in
+place for the process that created it, the file will inherit the SELinux label
+of the parent directory. So if a user creates a file themselves in `/tmp/`, it
+will get the SELinux label `tmp_t`, which VPP does not have permission to
+access. Therefore it is recommended that script files are located as described
+above.
+
+#### vHost Sockets
+
+vHost sockets are created from VPP perspective in either Server or Client mode.
+In Server mode, the socket name is provided to VPP and VPP creates the socket.
+In Client mode, the socket name is provided to VPP and the hypervisor creates
+the socket. In order for VPP and hypervisor to share the socket resource with
+SELinux enabled, a rule in the VPP Custom SELinux Policy has been added. This
+rules allows processes with the `svirt_t` label (the hypervisor) to access
+sockets with the `vpp_var_run_t` label. As such, when SELinux is enabled,
+vHost sockets should be created in the directory `/var/run/vpp/`.
+
+##### Original Documentation
+
+Some of the original documentation showed vHost sockets being created in the
+directory `/tmp/`. To work properly with SELinux enabled, vHost sockets should be
+created as described above.
+
+#### VPP Log Files
+
+The VPP log file location is set by updating the `/etc/vpp/startup.conf` file:
+
+```
+vi /etc/vpp/startup.conf
+unix {
+:
+  log /var/log/vpp/vpp.log
+:
+}
+
+```
+
+By moving the log file to `/var/log/vpp/`, it will get the label `vpp_log_t`,
+which indicates that the files are log files so they benefit from the
+associated rules (for example granting rights to logrotate so that it can
+manipulate them).
+
+##### Original Documentation
+
+The default `startup.conf` file creates the VPP log file in `/tmp/vpp.log`. By
+leaving the log file in `/tmp/`, it will get the label `vpp_tmp_t`. Moving it
+to `/var/log/vpp/`, it will get the label `vpp_log_t`.
+
+### Use of Non-default File Directories
+
+VPP installs multiple files on the system.
+Some files have fixed directory and file names:
+- /etc/bash_completion.d/vppctl_completion
+- /etc/sysctl.d/80-vpp.conf
+- /usr/lib/systemd/system/vpp.service
+
+Others files have default directory and file names but the default can be
+overwritten:
+- /etc/vpp/startup.conf
+  - Can be changed via the `/usr/lib/systemd/system/vpp.service` file by
+    changing the -c option on the VPP command line:
+
+```
+ExecStart=/usr/bin/vpp -c /etc/vpp/startup.conf
+```
+
+- /run/vpp/cli.sock
+  - Can be changed via the `/etc/vpp/startup.conf` file by changing the
+    cli-listen setting:
+
+```
+unix {
+:
+  cli-listen /run/vpp/cli.sock
+:
+}
+```
+
+
+- /var/log/vpp/vpp.log
+  - Can be changed via the `/etc/vpp/startup.conf` file by changing the log
+    setting:
+
+```
+unix {
+  :
+  log /var/log/vpp/vpp.log
+  :
+}
+
+```
+
+If the directory of any VPP installed files is changed from the default, ensure
+that the proper SELiunx label is applied. The SELinux label can be determined by
+passing the -Z option to many common Linux commands:
+
+```
+ls -alZ /run/vpp/
+drwxr-xr-x. root vpp  system_u:object_r:vpp_var_run_t:s0 .
+drwxr-xr-x. root root system_u:object_r:var_run_t:s0     ..
+srwxrwxr-x. root vpp  system_u:object_r:vpp_var_run_t:s0 cli.sock
+```
+
+### VPP SELinux Types ###
+
+The following SELinux types are created by the VPP Custom SELinux Policy:
+- `vpp_t` - Applied to:
+  - VPP process and spawned threads.
+
+- `vpp_config_rw_t` - Applied to:
+  - `/etc/vpp/*`
+
+- `vpp_tmp_t` - Applied to:
+  - `/tmp/*`
+
+- `vpp_exec_t` - Applied to:
+  - `/usr/bin/*`
+
+- `vpp_lib_t` - Applied to:
+  - `/usr/lib/vpp_api_test_plugins/*`
+  - `/usr/lib/vpp_plugins/*`
+
+- `vpp_unit_file_t` - Applied to:
+  - `/usr/lib/systemd/system/vpp.*`
+
+- `vpp_log_t` - Applied to:
+  - `/var/log/vpp/*`
+
+- `vpp_var_run_t` - Applied to:
+  - `/var/run/vpp/*`