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dropbear: fix hardening flags during configure 

compiler complains about messed up CFLAGS in build log:
  <command-line>: warning: "_FORTIFY_SOURCE" redefined
  <command-line>: note: this is the location of the previous definition

and then linker fails:
  mips-openwrt-linux-musl-gcc [...] -o dropbearmulti [...]
  collect2: fatal error: ld terminated with signal 11 [Segmentation fault]
  compilation terminated.
  /staging_dir/toolchain-mips_24kc_gcc-8.2.0_musl/mips-openwrt-linux-musl/bin/ld: /tmp/cc27zORz.ltrans0.ltrans.o: relocation R_MIPS_HI16 against `cipher_descriptor' can not be used when making a shared object; recompile with -fPIC
  /staging_dir/toolchain-mips_24kc_gcc-8.2.0_musl/mips-openwrt-linux-musl/bin/ld: /tmp/cc27zORz.ltrans1.ltrans.o: relocation R_MIPS_HI16 against `ses' can not be used when making a shared object; recompile with -fPIC
  /staging_dir/toolchain-mips_24kc_gcc-8.2.0_musl/mips-openwrt-linux-musl/bin/ld: /tmp/cc27zORz.ltrans2.ltrans.o: relocation R_MIPS_HI16 against `cipher_descriptor' can not be used when making a shared object; recompile with -fPIC
  /staging_dir/toolchain-mips_24kc_gcc-8.2.0_musl/mips-openwrt-linux-musl/bin/ld: BFD (GNU Binutils) 2.31.1 assertion fail elfxx-mips.c:6550
  [...]
  /staging_dir/toolchain-mips_24kc_gcc-8.2.0_musl/mips-openwrt-linux-musl/bin/ld: BFD (GNU Binutils) 2.31.1 assertion fail elfxx-mips.c:6550
  make[3]: *** [Makefile:198: dropbearmulti] Error 1
  make[3]: *** Deleting file 'dropbearmulti'
  make[3]: Leaving directory '/build_dir/target-mips_24kc_musl/dropbear-2018.76'
  make[2]: *** [Makefile:158: /build_dir/target-mips_24kc_musl/dropbear-2018.76/.built] Error 2
  make[2]: Leaving directory '/package/network/services/dropbear'

This FTBFS issue was caused by hardening flags set up by dropbear's configure script.

By default, Dropbear offers hardening via CFLAGS and LDFLAGS,
but this may break or confuse OpenWrt settings.

Remove most Dropbear's hardening settings in favour of precise build,
but preserve Spectre v2 mitigations:
* -mfunction-return=thunk
* -mindirect-branch=thunk

Signed-off-by: Konstantin Demin <rockdrilla@gmail.com>
openwrt-19.07
Konstantin Demin 2019-03-25 21:40:59 +03:00 committed by Hans Dedecker
parent a1099edf32
commit 9c3bfd0906
1 changed files with 56 additions and 0 deletions
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56
package/network/services/dropbear/patches/900-configure-hardening.patch Normal file
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@ -0,0 +1,56 @@
--- a/configure.ac
+++ b/configure.ac
@@ -70,53 +70,6 @@ AC_ARG_ENABLE(harden,
if test "$hardenbuild" -eq 1; then
AC_MSG_NOTICE(Checking for available hardened build flags:)
- # relocation flags don't make sense for static builds
- if test "$STATIC" -ne 1; then
- # pie
- DB_TRYADDCFLAGS([-fPIE])
-
- OLDLDFLAGS="$LDFLAGS"
- TESTFLAGS="-Wl,-pie"
- LDFLAGS="$LDFLAGS $TESTFLAGS"
- AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
- [AC_MSG_NOTICE([Setting $TESTFLAGS])],
- [
- LDFLAGS="$OLDLDFLAGS"
- TESTFLAGS="-pie"
- LDFLAGS="$LDFLAGS $TESTFLAGS"
- AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
- [AC_MSG_NOTICE([Setting $TESTFLAGS])],
- [AC_MSG_NOTICE([Not setting $TESTFLAGS]); LDFLAGS="$OLDLDFLAGS" ]
- )
- ]
- )
- # readonly elf relocation sections (relro)
- OLDLDFLAGS="$LDFLAGS"
- TESTFLAGS="-Wl,-z,now -Wl,-z,relro"
- LDFLAGS="$LDFLAGS $TESTFLAGS"
- AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
- [AC_MSG_NOTICE([Setting $TESTFLAGS])],
- [AC_MSG_NOTICE([Not setting $TESTFLAGS]); LDFLAGS="$OLDLDFLAGS" ]
- )
- fi # non-static
- # stack protector. -strong is good but only in gcc 4.9 or later
- OLDCFLAGS="$CFLAGS"
- TESTFLAGS="-fstack-protector-strong"
- CFLAGS="$CFLAGS $TESTFLAGS"
- AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])],
- [AC_MSG_NOTICE([Setting $TESTFLAGS])],
- [
- CFLAGS="$OLDCFLAGS"
- TESTFLAGS="-fstack-protector --param=ssp-buffer-size=4"
- CFLAGS="$CFLAGS $TESTFLAGS"
- AC_COMPILE_IFELSE([AC_LANG_PROGRAM([])],
- [AC_MSG_NOTICE([Setting $TESTFLAGS])],
- [AC_MSG_NOTICE([Not setting $TESTFLAGS]); CFLAGS="$OLDCFLAGS" ]
- )
- ]
- )
- # FORTIFY_SOURCE
- DB_TRYADDCFLAGS([-D_FORTIFY_SOURCE=2])
# Spectre v2 mitigations
DB_TRYADDCFLAGS([-mfunction-return=thunk])