From 34fd7ba6ccc4368f87bcfc8e4ef702496e4c5655 Mon Sep 17 00:00:00 2001
From: Kevin Haubris <kevin.haubris@gmail.com>
Date: Mon, 16 May 2022 12:48:34 -0500
Subject: [PATCH] Added changes and example of building as .so file, a runner.c
 file, and how to run it for #1

---
 Makefile                     |  7 ++++++
 README.md                    |  8 ++++++
 includes/ELFRunner_include.h |  8 ++++++
 runner.c                     | 48 ++++++++++++++++++++++++++++++++++++
 src/ELFLoader.c              |  8 ++++--
 src/beacon_compatibility.c   |  3 +++
 6 files changed, 80 insertions(+), 2 deletions(-)
 create mode 100644 includes/ELFRunner_include.h
 create mode 100644 runner.c

diff --git a/Makefile b/Makefile
index 5a4bc0a..ea2b312 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,12 @@ x86_64:
 x86_64D:
 	gcc -g -DDEBUG -Wall -I ./includes/ -DTESTING_MAIN $(SOURCES) -ldl -o ELFLoaderD.out
 
+x86_64so:
+	gcc -shared -fPIC -fvisibility=hidden -DLIBRARY -Wall -I ./includes/ -DTESTING_MAIN $(SOURCES) -ldl -o libELFLoader.so
+
+x86_64runner:
+	gcc -I ./includes/ runner.c -o runner.out -L . -lELFLoader
+
 x86_64_bsd:
 	gcc -Wall -I ./includes/ -DTESTING_MAIN $(SOURCES) -o ELFLoader_bsd.out
 
@@ -124,4 +130,5 @@ clean:
 	rm -f ./SA/src/*.o
 	rm -f testobjects/*.o
 	rm -f ELFLoader_public
+	rm -f libELFLoader.so
 .PHONY: x86_64 x86_64D test2_dup test2 test clean
diff --git a/README.md b/README.md
index a4da826..32f6320 100644
--- a/README.md
+++ b/README.md
@@ -115,3 +115,11 @@ This is the generic example that doesn't take any arguments.
 ```
 ./ELFLoader.out SA/src/uname.o
 ```
+
+### Runner and Library Example
+
+```
+make x86_64so
+make x86_64runner
+LD_LIBRARY_PATH=. ./runner.out ./SA/src/env.o
+```
diff --git a/includes/ELFRunner_include.h b/includes/ELFRunner_include.h
new file mode 100644
index 0000000..b273279
--- /dev/null
+++ b/includes/ELFRunner_include.h
@@ -0,0 +1,8 @@
+#ifndef ELFLOADER_INCLUDE_H_
+#define ELFLOADER_INCLUDE_H_
+
+int ELFRunner(char* functionName, unsigned char* elfObjectData, unsigned int size, unsigned char* argumentdata, int argumentSize);
+char* BeaconGetOutputData(int *outsize);
+unsigned char* unhexlify(unsigned char* value, int *outlen);
+
+#endif
diff --git a/runner.c b/runner.c
new file mode 100644
index 0000000..861a157
--- /dev/null
+++ b/runner.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <ELFRunner_include.h>
+
+int main(int argc, char** argv, char** envp)
+{
+    //int (*ptr)(char*, int*);
+    unsigned char* buf = NULL;
+    int size = 0;
+    FILE* elf = NULL;
+    int checkcode = 0;
+    char* outputdata = NULL;
+    char* argumentdata = NULL;
+    int argumentdatalen = 0;
+    int outputdataLen = 0;
+
+    if (argc < 2){
+        printf("%s ./path/to/objectfile.o\n", argv[0]);
+        return 0;
+    }
+    elf = fopen(argv[1], "rb");
+    if (elf == NULL){
+        printf("ERROR: File doesn't exist\n");
+        return 0;
+    }
+    fseek(elf, 0, SEEK_END);
+    size = ftell(elf);
+    fseek(elf, 0, SEEK_SET);
+    buf = calloc(size, 1);
+    if (buf == NULL){
+        return 0;
+    }
+    (void)fread(buf, 1, size, elf);
+    argumentdata = (char*)unhexlify((unsigned char*)argv[2], &argumentdatalen);
+    checkcode = ELFRunner("go", buf, size, (unsigned char*)argumentdata, argumentdatalen );
+    if (checkcode == 0){
+        outputdata = BeaconGetOutputData(&outputdataLen);
+        printf("Output data : %s\n", outputdata);
+        free(outputdata);
+    }
+
+
+    free(buf);
+    fclose(elf);
+    return 0;
+}
+
diff --git a/src/ELFLoader.c b/src/ELFLoader.c
index f39c954..65ac0e4 100644
--- a/src/ELFLoader.c
+++ b/src/ELFLoader.c
@@ -14,7 +14,9 @@
 #include "ELFLoader.h"
 #include "beacon_compatibility.h"
 
-
+#ifdef LIBRARY
+__attribute__ ((visibility ("default")))
+#endif
 unsigned char* unhexlify(unsigned char* value, int *outlen){
     unsigned char* retval = NULL;
     char byteval[3] = {0};
@@ -48,7 +50,9 @@ errcase:
     return retval;
 }
 
-
+#ifdef LIBRARY
+__attribute__ ((visibility ("default")))
+#endif
 int ELFRunner(char* functionName, unsigned char* elfObjectData, unsigned int size, unsigned char* argumentdata, int argumentSize){
 #if defined(__amd64__) || defined(__x86_64__) || defined(__i386__) || (defined(DEBUG) && defined(ELFRUNNERTEST))
     ELFInfo_t elfinfo;
diff --git a/src/beacon_compatibility.c b/src/beacon_compatibility.c
index 93fc1b0..a7cc43e 100644
--- a/src/beacon_compatibility.c
+++ b/src/beacon_compatibility.c
@@ -318,6 +318,9 @@ int BeaconIsAdmin(void){
     return 0;
 }
 
+#ifdef LIBRARY
+__attribute__ ((visibility ("default")))
+#endif
 char* BeaconGetOutputData(int *outsize){
     char* outdata = beacon_compatibility_output;
     *outsize = beacon_compatibility_size;