hardening flags for fedora rpmbuilds

This commit sets the CGO_CFLAGS variable for hardening the Fedora rpm
binaries.

The flags used are the same as those in the official Fedora rpms.
Setting the flags in upstream spec would provide early warnings for
flag adjustments or other hardening issues.

(cherry picked from commit 21deafb)

Signed-off-by: Lokesh Mandvekar <[email protected]>

contrib/spec/podman.spec.in

@@ -380,6 +380,29 @@ tar zxf %{SOURCE1}
 %build
 mkdir _build
 pushd _build
+
+# These flags should work for all rpm distros and arches
+export CGO_CFLAGS="-O2 -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -ffat-lto-objects -fexceptions -fasynchronous-unwind-tables -fstack-protector-strong -fstack-clash-protection -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE"
+
+%if 0%{?fedora} || 0%{?rhel}
+# This flag is only present on RH-family distros
+export CGO_CFLAGS+=" -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1"
+%endif
+
+%ifnarch %{ix86}
+# Build fails on i686 with this flag
+export CGO_CFLAGS+=" -D_FILE_OFFSET_BITS=64"
+%endif
+
+%ifarch x86_64
+# Builds only on x86_64 with this flag
+export CGO_CFLAGS+=" -m64 -mtune=generic"
+%if 0%{?fedora} || 0%{?rhel} >= 8
+# Build fails on rhel7 and non-86_64 with this flag
+export CGO_CFLAGS+=" -fcf-protection"
+%endif
+%endif
+
 mkdir -p src/%{provider}.%{provider_tld}/%{project}
 ln -s ../../../../ src/%{import_path}
 popd