initial

src/zap-args.c

@@ -0,0 +1,63 @@
+/*
+ * gcc -Wall -O2 -fpic -shared -o zap-args.so zap-args.c -ldl
+ *
+ * LD_PRELOAD=./zap-args.so exec -a syslogd nmap -T0 10.0.0.1/24
+ */
+#define _GNU_SOURCE 
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <dlfcn.h>
+
+typedef int (*pfi)(int, char **, char **);
+static pfi real_main;
+
+/*
+ * Copy original argv to new location and delete original location
+ * so that 'ps alxww' wont have anything to display.
+ */
+char **copyargs(int argc, char** argv){
+    char **newargv = malloc((argc+1)*sizeof(*argv));
+    char *from,*to;
+    int i,len;
+
+    for(i = 0; i<argc; i++){
+        from = argv[i];
+        len = strlen(from)+1;
+        to = malloc(len);
+        memcpy(to,from,len);
+	// Zap the old args but not the programm name
+	if (i >= 1)
+	        memset(from,'\0',len);
+        newargv[i] = to;
+        argv[i] = 0;
+    }
+    newargv[argc] = 0;
+    return newargv;
+}
+
+static int mymain(int argc, char** argv, char** env) {
+    return real_main(argc, copyargs(argc,argv), env);
+}
+
+int __libc_start_main(pfi main, int argc,
+                      char **ubp_av, void (*init) (void),
+                      void (*fini)(void),
+                      void (*rtld_fini)(void), void (*stack_end)){
+    static int (*real___libc_start_main)() = NULL;
+
+    if (!real___libc_start_main) {
+        char *error;
+        real___libc_start_main = dlsym(RTLD_NEXT, "__libc_start_main");
+        if ((error = dlerror()) != NULL) {
+            fprintf(stderr, "%s\n", error);
+            exit(1);
+        }
+    }
+    real_main = main;
+    return real___libc_start_main(mymain, argc, ubp_av, init, fini,
+            rtld_fini, stack_end);
+}
+