From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Fri, 9 Mar 2018 02:35:20 +0000 (-0600)
Subject: misc: enable retpolines across all xfsprogs utilities
X-Git-Tag: v4.16.0-rc1~62
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1b0adc71229ba8611b06abc2bffa03babba5157d;p=thirdparty%2Fxfsprogs-dev.git

misc: enable retpolines across all xfsprogs utilities

Detect and enable retpolines for all code, to mitigate Spectre v2
(branch target injection) on x86.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

diff --git a/configure.ac b/configure.ac
index 3a0ab184a..b0d26016d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -206,6 +206,7 @@ if test "$have_threadsan" = "yes" && test "$have_addrsan" = "yes"; then
         AC_MSG_WARN([ADDRSAN and THREADSAN are not known to work together.])
 fi
 
+AC_PACKAGE_CHECK_RETPOLINE
 AC_CHECK_SIZEOF([long])
 AC_CHECK_SIZEOF([char *])
 AC_TYPE_UMODE_T
diff --git a/include/builddefs.in b/include/builddefs.in
index df76b2c16..fe05dc376 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -176,6 +176,13 @@ endif
 SANITIZER_CFLAGS += @addrsan_cflags@ @threadsan_cflags@ @ubsan_cflags@
 SANITIZER_LDFLAGS += @addrsan_ldflags@ @threadsan_ldflags@ @ubsan_ldflags@
 
+# Enable retpolines if available
+HAVE_RETPOLINE = @have_retpoline@
+ifeq ($(HAVE_RETPOLINE),yes)
+OPTIMIZER += @retpoline_cflags@
+LOADERFLAGS += @retpoline_ldflags@
+endif
+
 GCFLAGS = $(DEBUG) \
 	  -DVERSION=\"$(PKG_VERSION)\" -DLOCALEDIR=\"$(PKG_LOCALE_DIR)\"  \
 	  -DPACKAGE=\"$(PKG_NAME)\" -I$(TOPDIR)/include -I$(TOPDIR)/libxfs
diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
index 9258c271f..5a7baa1e5 100644
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -420,3 +420,25 @@ AC_DEFUN([AC_HAVE_HDIO_GETGEO],
        AC_MSG_RESULT(no))
     AC_SUBST(have_hdio_getgeo)
   ])
+
+AC_DEFUN([AC_PACKAGE_CHECK_RETPOLINE],
+  [ AC_MSG_CHECKING([if C compiler supports retpoline])
+    OLD_CFLAGS="$CFLAGS"
+    OLD_LDFLAGS="$LDFLAGS"
+    RETPOLINE_FLAGS="-mindirect-branch=thunk"
+    CFLAGS="$CFLAGS $RETPOLINE_FLAGS"
+    LDFLAGS="$LDFLAGS $RETPOLINE_FLAGS"
+    AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
+        [AC_MSG_RESULT([yes])]
+        [retpoline_cflags=$RETPOLINE_FLAGS]
+        [retpoline_ldflags=$RETPOLINE_FLAGS],
+        [AC_MSG_RESULT([no])])
+    if test -n "$retpoline_cflags"; then
+        have_retpoline=yes
+    fi
+    CFLAGS="${OLD_CFLAGS}"
+    LDFLAGS="${OLD_LDFLAGS}"
+    AC_SUBST(have_retpoline)
+    AC_SUBST(retpoline_cflags)
+    AC_SUBST(retpoline_ldflags)
+  ])