add initial version of ujail and utrace

[project/procd.git] / trace / preload.c

diff --git a/trace/preload.c b/trace/preload.c
new file mode 100644 (file)
index 0000000..99dd906
--- /dev/null
+++ b/trace/preload.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define _GNU_SOURCE
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <dlfcn.h>
+
+#include "../preload.h"
+
+#define ERROR(fmt, ...) do { \
+       fprintf(stderr,"perload-jail: "fmt, ## __VA_ARGS__); \
+       } while (0)
+
+static main_t __main__;
+
+static int __preload_main__(int argc, char **argv, char **envp)
+{
+       unsetenv("LD_PRELOAD");
+       ptrace(PTRACE_TRACEME);
+       kill(getpid(), SIGSTOP);
+
+       return (*__main__)(argc, argv, envp);
+}
+
+int __libc_start_main(main_t main,
+                       int argc,
+                       char **argv,
+                       ElfW(auxv_t) *auxvec,
+                       __typeof (main) init,
+                       void (*fini) (void),
+                       void (*rtld_fini) (void),
+                       void *stack_end)
+{
+       start_main_t __start_main__;
+
+       __start_main__ = dlsym(RTLD_NEXT, "__libc_start_main");
+       if (!__start_main__)
+               ERROR("failed to find __libc_start_main %s\n", dlerror());
+
+       __main__ = main;
+
+       return (*__start_main__)(__preload_main__, argc, argv, auxvec,
+               init, fini, rtld_fini, stack_end);
+}
+
+void __uClibc_main(main_t main,
+                       int argc,
+                       char **argv,
+                       void (*app_init)(void),
+                       void (*app_fini)(void),
+                       void (*rtld_fini)(void),
+                       void *stack_end attribute_unused)
+{
+       uClibc_main __start_main__;
+
+       __start_main__ = dlsym(RTLD_NEXT, "__uClibc_main");
+       if (!__start_main__)
+               ERROR("failed to find __uClibc_main %s\n", dlerror());
+
+       __main__ = main;
+
+       return (*__start_main__)(__preload_main__, argc, argv,
+               app_init, app_fini, rtld_fini, stack_end);
+}