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Add hidesu program.

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This is a test program, this will probably be integrated into su daemon.
This hides su by bind-mounting something (/system) over /sbin, so that
there is no /sbin/su binary.
Usage:
hidesu /proc/<one pid of the namespace>/ns/mnt

This uses the fact that when a program wants access to /sdcard, zygote
does this using mount namespaces, so every program accessing /sdcard
will be in a custom mount namespace, that can be modified.
This commit is contained in:
Pierre-Hugues Husson 2016-09-27 00:08:18 +02:00 committed by topjohnwu
parent 2d6fb1c45e
commit e1279c29c2
2 changed files with 31 additions and 0 deletions
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9
jni/Android.mk
View File

@ -2,6 +2,15 @@ my_path := $(call my-dir)
LOCAL_PATH := $(my_path) LOCAL_PATH := $(my_path)
include $(CLEAR_VARS)
LOCAL_MODULE := hidesu
LOCAL_MODULE_TAGS := optional
LOCAL_FORCE_STATIC_EXECUTABLE := true
LOCAL_LDFLAGS := -static
LOCAL_STATIC_LIBRARIES := libc libcutils
LOCAL_SRC_FILES := hidesu.c
include $(BUILD_EXECUTABLE)
include $(CLEAR_VARS) include $(CLEAR_VARS)
LOCAL_MODULE := bootimgtools LOCAL_MODULE := bootimgtools
LOCAL_MODULE_TAGS := optional LOCAL_MODULE_TAGS := optional

22
jni/hidesu.c Normal file
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@ -0,0 +1,22 @@
#define _GNU_SOURCE
#include <sched.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/mount.h>
#include <sys/syscall.h>
int main(int argc, char **argv) {
if(argc != 2) exit(5);
int fd = open(argv[1], O_RDONLY);
if(fd == -1) exit(2);
//TODO: Fix non arm platforms
#define SYS_setns 375
int res = syscall(SYS_setns, fd, 0);
if(res == -1) exit(3);
//XXX: What to mount to /sbin...?
res = mount("/system", "/sbin", "bind", MS_BIND, "");
if(res == -1) exit(4);
exit(0);
}