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, 10 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 8ee2fbadc..3c9f901cb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -184,6 +184,15 @@ AS_IF([test "x$enable_contrib_install" = "xno"],
 )
 AC_SUBST(HAVE_CONTRIB_INSTALL)
 
+HAVE_SELINUX=""
+AC_ARG_ENABLE([selinux],
+    AS_HELP_STRING([--enable-selinux], [SELinux labeling support]))
+AS_IF([test "x$enable_selinux" = "xyes"], [
+        HAVE_SELINUX="-DHAVE_SELINUX"
+        EXTRA_LDFLAGS+=" -lselinux "
+        AC_SUBST(HAVE_SELINUX)
+])
+
 # checking pthread library
 AC_CHECK_LIB([pthread], [main], [], AC_MSG_ERROR([*** POSIX thread support not installed ***]))
 AC_CHECK_HEADER(pthread.h,,AC_MSG_ERROR([*** POSIX thread support not installed ***]))
@@ -223,5 +232,6 @@ 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