Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a377ff0d authored by Jorge Lucangeli Obes's avatar Jorge Lucangeli Obes
Browse files

run-as: Use Minijail for privilege dropping. 

Arguably, we don't need a ScopedMinijail for a program that only execs,
but I'd rather keep the code consistent and have all uses of Minijail
be good examples.

Bug: 30156807

Change-Id: I08a968835e0f3e2afcd5e7736626edbed658cde2
parent ddbcecec

run-as/Android.mk

+2 −2
Original line number Diff line number Diff line 
LOCAL_PATH:= $(call my-dir)



include $(CLEAR_VARS)

LOCAL_CFLAGS := -Werror

LOCAL_CFLAGS := -Wall -Werror

LOCAL_MODULE := run-as

LOCAL_SHARED_LIBRARIES := libselinux libpackagelistparser

LOCAL_SHARED_LIBRARIES := libselinux libpackagelistparser libminijail

LOCAL_SRC_FILES := run-as.cpp

include $(BUILD_EXECUTABLE)

run-as/run-as.cpp

+7 −25
Original line number Diff line number Diff line
@@ -25,6 +25,9 @@ 
#include <sys/types.h>

#include <unistd.h>



#include <libminijail.h>

#include <scoped_minijail.h>



#include <packagelistparser/packagelistparser.h>

#include <private/android_filesystem_config.h>

#include <selinux/android.h>
@@ -136,19 +139,6 @@ int main(int argc, char* argv[]) { 
    error(1, 0, "only 'shell' or 'root' users can run this program");

  }



  __user_cap_header_struct capheader;

  __user_cap_data_struct capdata[2];

  memset(&capheader, 0, sizeof(capheader));

  memset(&capdata, 0, sizeof(capdata));

  capheader.version = _LINUX_CAPABILITY_VERSION_3;

  capdata[CAP_TO_INDEX(CAP_SETUID)].effective |= CAP_TO_MASK(CAP_SETUID);

  capdata[CAP_TO_INDEX(CAP_SETGID)].effective |= CAP_TO_MASK(CAP_SETGID);

  capdata[CAP_TO_INDEX(CAP_SETUID)].permitted |= CAP_TO_MASK(CAP_SETUID);

  capdata[CAP_TO_INDEX(CAP_SETGID)].permitted |= CAP_TO_MASK(CAP_SETGID);

  if (capset(&capheader, &capdata[0]) == -1) {

    error(1, errno, "couldn't set capabilities");

  }



  char* pkgname = argv[1];

  int cmd_argv_offset = 2;
@@ -201,18 +191,10 @@ int main(int argc, char* argv[]) { 
  // same time to avoid nasty surprises.

  uid_t uid = userAppId;

  uid_t gid = userAppId;

  if (setresgid(gid, gid, gid) == -1) {

    error(1, errno, "setresgid failed");

  }

  if (setresuid(uid, uid, uid) == -1) {

    error(1, errno, "setresuid failed");

  }



  // Required if caller has uid and gid all non-zero.

  memset(&capdata, 0, sizeof(capdata));

  if (capset(&capheader, &capdata[0]) == -1) {

    error(1, errno, "couldn't clear all capabilities");

  }

  ScopedMinijail j(minijail_new());

  minijail_change_uid(j.get(), uid);

  minijail_change_gid(j.get(), gid);

  minijail_enter(j.get());



  if (selinux_android_setcontext(uid, 0, info.seinfo, pkgname) < 0) {

    error(1, errno, "couldn't set SELinux security context");