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Commit c96f53e2 authored by Jorge Lucangeli Obes's avatar Jorge Lucangeli Obes
Browse files

Use Minijail for privilege dropping. 

Having so many copies of privilege-dropping code leads to errors.
De-duplicate this code and use Minijail for it.

Bug: 30156807

Change-Id: I36c85962b913a12efe5648a23cbacc5bcbb3853c
parent a17427cb

sdcard/Android.mk

+1 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ include $(CLEAR_VARS) 
LOCAL_SRC_FILES := sdcard.cpp fuse.cpp

LOCAL_MODULE := sdcard

LOCAL_CFLAGS := -Wall -Wno-unused-parameter -Werror

LOCAL_SHARED_LIBRARIES := libbase liblog libcutils libpackagelistparser

LOCAL_SHARED_LIBRARIES := libbase liblog libcutils libminijail libpackagelistparser



LOCAL_SANITIZE := integer

LOCAL_CLANG := true

sdcard/sdcard.cpp

+14 −10
Original line number Diff line number Diff line
@@ -36,6 +36,9 @@ 
#include <cutils/multiuser.h>

#include <packagelistparser/packagelistparser.h>



#include <libminijail.h>

#include <scoped_minijail.h>



#include <private/android_filesystem_config.h>



// README
@@ -204,6 +207,15 @@ static int fuse_setup(struct fuse* fuse, gid_t gid, mode_t mask) { 
    return 0;

}



static void drop_privs(uid_t uid, gid_t gid) {

    ScopedMinijail j(minijail_new());

    minijail_set_supplementary_gids(j.get(), sizeof(kGroups) / sizeof(kGroups[0]), kGroups);

    minijail_change_gid(j.get(), gid);

    minijail_change_uid(j.get(), uid);

    /* minijail_enter() will abort if priv-dropping fails. */

    minijail_enter(j.get());

}



static void* start_handler(void* data) {

    struct fuse_handler* handler = static_cast<fuse_handler*>(data);

    handle_fuse_requests(handler);
@@ -299,16 +311,8 @@ static void run(const char* source_path, const char* label, uid_t uid, 
        }

    }



    /* Drop privs. */

    if (setgroups(sizeof(kGroups) / sizeof(kGroups[0]), kGroups) < 0) {

        PLOG(FATAL) << "cannot setgroups";

    }

    if (setgid(gid) < 0) {

        PLOG(FATAL) << "cannot setgid";

    }

    if (setuid(uid) < 0) {

        PLOG(FATAL) << "cannot setuid";

    }

    // Will abort if priv-dropping fails.

    drop_privs(uid, gid);



    if (multi_user) {

        fs_prepare_dir(global.obb_path, 0775, uid, gid);