Add support for SELinux labeling

Running `firejail --noprofile --private-bin=bash,ls ls -1Za /usr/bin`
shows that the SELinux labels are not correct:
```
user_u:object_r:user_tmpfs_t:s0 .
     system_u:object_r:usr_t:s0 ..
user_u:object_r:user_tmpfs_t:s0 bash
user_u:object_r:user_tmpfs_t:s0 ls
```

After fixing this:
```
       system_u:object_r:bin_t:s0 .
       system_u:object_r:usr_t:s0 ..
system_u:object_r:shell_exec_t:s0 bash
       system_u:object_r:bin_t:s0 ls
```

Most copied files and created directories should now have correct
labels (bind mounted objects keep their labels). This is useful to
avoid having to change the SELinux rules when using Firejail.

1 files changed, 18 insertions, 0 deletions

diff --git a/configure b/configure
index 94f719710..53ea8f19d 100755
--- a/configure
+++ b/configure
@@ -628,6 +628,7 @@ HAVE_SECCOMP_H
 EGREP
 GREP
 CPP
+HAVE_SELINUX
 HAVE_CONTRIB_INSTALL
 HAVE_GCOV
 BUSYBOX_WORKAROUND
@@ -721,6 +722,7 @@ enable_fatal_warnings
 enable_busybox_workaround
 enable_gcov
 enable_contrib_install
+enable_selinux
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1365,6 +1367,7 @@ Optional Features:
   --enable-gcov           Gcov instrumentation
   --enable-contrib-install
                           install contrib scripts
+  --enable-selinux        SELinux labeling support
 
 Some influential environment variables:
   CC          C compiler command
@@ -3695,6 +3698,20 @@ else
 fi
 
 
+HAVE_SELINUX=""
+# Check whether --enable-selinux was given.
+if test "${enable_selinux+set}" = set; then :
+  enableval=$enable_selinux;
+fi
+
+if test "x$enable_selinux" = "xyes"; then :
+
+        HAVE_SELINUX="-DHAVE_SELINUX"
+        EXTRA_LDFLAGS+=" -lselinux "
+
+
+fi
+
 # checking pthread library
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -lpthread" >&5
 $as_echo_n "checking for main in -lpthread... " >&6; }
@@ -5364,5 +5381,6 @@ echo "   EXTRA_CFLAGS: $EXTRA_CFLAGS"
 echo "   fatal warnings: $HAVE_FATAL_WARNINGS"
 echo "   Gcov instrumentation: $HAVE_GCOV"
 echo "   Install contrib scripts: $HAVE_CONTRIB_INSTALL"
+echo "   SELinux labeling support: $HAVE_SELINUX"
 echo "   Install as a SUID executable: $HAVE_SUID"
 echo