Merge pull request #2192 from brauner/2018-02-26/enable_pam_flag

configure: add --enable-pam

configure.ac

@@ -607,6 +607,43 @@ else
 fi
 AM_CONDITIONAL([IS_BIONIC], [test "x$is_bionic" = "xyes"])
 
+# Configuration examples
+AC_ARG_ENABLE([pam],
+	[AC_HELP_STRING([--enable-pam], [enable pam module [default=no]])],
+	[], [enable_pam=no])
+AM_CONDITIONAL([ENABLE_PAM], [test "x$enable_pam" = "xyes"])
+
+AM_COND_IF([ENABLE_PAM],
+	[AC_ARG_WITH(
+		[pamdir],
+		[AS_HELP_STRING([--with-pamdir=PATH],[Specify the directory where PAM modules are stored,
+							or "none" if PAM modules are not to be built])],
+		[pamdir="${withval}"],
+		[
+			if test "${prefix}" = "/usr"; then
+				pamdir="/lib${libdir##*/lib}/security"
+			else
+				pamdir="\$(libdir)/security"
+			fi
+		]
+	)])
+
+AM_CONDITIONAL([HAVE_PAM], [test x"$pamdir" != "xnone"])
+AM_COND_IF([ENABLE_PAM],
+	[if test "z$pamdir" != "znone"; then
+		AC_ARG_VAR([PAM_CFLAGS], [C compiler flags for pam])
+		AC_ARG_VAR([PAM_LIBS], [linker flags for pam])
+		AC_CHECK_LIB(
+			[pam],
+			[pam_authenticate],
+			[PAM_LIBS="-lpam"],
+			[AC_MSG_ERROR([*** libpam not found.])
+			])
+
+		AC_SUBST(PAM_LIBS)
+		AC_SUBST([pamdir])
+	fi])
+
 # Some systems lack PR_CAPBSET_DROP definition => HAVE_DECL_PR_CAPBSET_DROP
 AC_CHECK_DECLS([PR_CAPBSET_DROP], [], [], [#include <sys/prctl.h>])
 
@@ -927,6 +964,10 @@ Security features:
  - seccomp: $enable_seccomp
  - SELinux: $enable_selinux
 
+PAM:
+ - PAM module: $enable_pam
+ - cgroup PAM module: $pamdir
+
 Bindings:
  - lua: $enable_lua
  - python3: $enable_python