[RFC PATCH liburing v1 2/3] configure: Introduce '--use-libc' option

[Ammar Faizi]

Currently, when compiling liburing on x86, x86-64, and aarch64
architectures, the resulting binary lacks the linkage with the standard
C library (libc).

To address the concerns raised by Linux distribution package maintainers
regarding security, it is necessary to enable the linkage of libc to
liburing. Especially right now, when the security of io_uring is being
scrutinized. By incorporating the '--use-libc' option, developers can
now enhance the overall hardening of liburing by utilizing compiler
features such as the stack protector and address sanitizer.

Link: https://security.googleblog.com/2023/06/learnings-from-kctf-vrps-42-linux.html
Link: https://lore.kernel.org/io-uring/20230621100447.GD2667602@fedora
Link: https://lore.kernel.org/io-uring/ZJLkXC7QffsoCnpu@xxxxxxxxxxxxxxxxxxx
Cc: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
Cc: Guillem Jover <guillem@xxxxxxxxxxx>
Co-authored-by: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxxxx>
Signed-off-by: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxxxx>
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
---
 configure | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/configure b/configure
index a16ffca83d678364..46afb7285a1ea8d0 100755
--- a/configure
+++ b/configure
@@ -26,6 +26,8 @@ for opt do
   ;;
   --cxx=*) cxx="$optarg"
   ;;
+  --use-libc) use_libc=yes
+  ;;
   *)
     echo "ERROR: unknown option $opt"
     echo "Try '$0 --help' for more information"
@@ -73,6 +75,7 @@ Options: [defaults in brackets after descriptions]
   --datadir=PATH           install shared data in PATH [$datadir]
   --cc=CMD                 use CMD as the C compiler
   --cxx=CMD                use CMD as the C++ compiler
+  --use-libc               use libc for liburing (useful for hardening)
 EOF
 exit 0
 fi
@@ -382,10 +385,13 @@ fi
 print_config "NVMe uring command support" "$nvme_uring_cmd"
 
 #############################################################################
-#
-# Currently, CONFIG_NOLIBC is only enabled on x86-64, x86 (32-bit) and aarch64.
-#
-cat > $TMPC << EOF
+liburing_nolibc="no"
+if test "$use_libc" != "yes"; then
+
+  #
+  # Currently, CONFIG_NOLIBC only supports x86-64, x86 (32-bit) and aarch64.
+  #
+  cat > $TMPC << EOF
 int main(void){
 #if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__)
   return 0;
@@ -394,10 +400,13 @@ int main(void){
 #endif
 }
 EOF
-if compile_prog "" "" "nolibc support"; then
-  liburing_nolibc="yes"
+
+  if compile_prog "" "" "nolibc"; then
+    liburing_nolibc="yes"
+  fi
 fi
-print_config "nolibc support" "$liburing_nolibc";
+
+print_config "nolibc" "$liburing_nolibc";
 #############################################################################
 
 ####################################################
-- 
Ammar Faizi