Add HAProxy static PIE ELF

Add HAProxy static PIE ELF. Add instructions and helper scripts to build HAProxy as a static PIE ELF.

Co-authored-by: Gabriele Pappalardo <leleattolo99@gmail.com>
Co-authored-by: Alberto Zurini <alberto.zurini@gmail.com>
Co-authored-by: Federico Bertossi <livebymax@gmail.com>
Signed-off-by: Alessandro Grassi <alessandrograssi17@gmail.com>

haproxy/Makefile.patch

@@ -0,0 +1,18 @@
+--- Makefile_OLD.txt	2022-10-23 16:24:37.113951164 +0200
++++ Makefile	2022-10-23 15:25:44.686153369 +0200
+@@ -326,13 +326,13 @@
+ # These CFLAGS contain general optimization options, CPU-specific optimizations
+ # and debug flags. They may be overridden by some distributions which prefer to
+ # set all of them at once instead of playing with the CPU and DEBUG variables.
+-CFLAGS = $(ARCH_FLAGS) $(CPU_CFLAGS) $(DEBUG_CFLAGS) $(SPEC_CFLAGS)
++CFLAGS = -fPIC $(ARCH_FLAGS) $(CPU_CFLAGS) $(DEBUG_CFLAGS) $(SPEC_CFLAGS)
+
+ #### Common LDFLAGS
+ # These LDFLAGS are used as the first "ld" options, regardless of any library
+ # path or any other option. They may be changed to add any linker-specific
+ # option at the beginning of the ld command line.
+-LDFLAGS = $(ARCH_FLAGS) -g
++LDFLAGS = -static-pie $(ARCH_FLAGS) -g
+
+ #### list of all "USE_*" options. These ones must be updated if new options are
+ # added, so that the relevant options are properly added to the CFLAGS and to

haproxy/README.md

@@ -0,0 +1,27 @@
+# Build HAProxy as static PIE
+
+Build the [HAProxy](https://git.haproxy.org/): The Reliable, High Performance TCP/HTTP Load Balancer as a static PIE ELF running on Linux.
+
+## Requirements
+
+Make sure the following packages are installed:
+* gcc >= 8 (required for the `-static-pie` linking option)
+* autotools
+* GNU Make
+* zlib development files
+* OpenSSL development files
+
+For Ubuntu, run the command below to install all requirements:
+
+```
+$ sudo apt install build-essential zlib1g-dev libssl-dev
+```
+
+## Build
+
+The `HAProxy` static PIE ELF is located in the current folder.
+If you want to rebuild it, run:
+
+```
+$ ./build.sh
+```

haproxy/build.sh

@@ -0,0 +1,16 @@
+\#!/bin/bash
+
+# Clean up.
+rm -fr haproxy-git
+
+echo -n "Downloading HAProxy ... "
+git clone https://github.com/haproxy/haproxy.git haproxy-git
+echo ""
+echo -n "Building HAProxy ... "
+pushd haproxy-git > /dev/null 2>&1
+patch Makefile < ../Makefile.patch
+make TARGET=linux-glibc-legacy
+popd > /dev/null 2>&1
+
+cp haproxy-git/haproxy .
+rm -fr haproxy-git