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#!/usr/bin/python3
# resources for cffi:
# http://eli.thegreenplace.net/2013/03/09/python-ffi-with-ctypes-and-cffi
import cffi
import os
import time
import pwd
pid = os.getpid()
print('pid:', pid)
ffi = cffi.FFI()
libc = ffi.dlopen('libc.so.6')
libcap = ffi.dlopen('libcap.so.2')
ffi.cdef('''
typedef struct _cap_struct *cap_t;
typedef int cap_value_t;
typedef enum {
CAP_EFFECTIVE=0,
CAP_PERMITTED=1,
CAP_INHERITABLE=2
} cap_flag_t;
typedef enum {
CAP_CLEAR=0,
CAP_SET=1
} cap_flag_value_t;
int prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
cap_t cap_get_proc(void);
int cap_set_flag(cap_t cap_p, cap_flag_t flag, int ncap,
const cap_value_t *caps, cap_flag_value_t value);
cap_t cap_init(void);
int cap_free(void *obj_d);
int cap_set_proc(cap_t cap_p);
''')
PR_SET_KEEPCAPS = 8
PR_SET_NAME = 15
CAP_EFFECTIVE = 0
CAP_PERMITTED = 1
CAP_INHERITABLE = 2
CAP_CLEAR = 0
CAP_SET = 1
# generated list with command line below:
# sed -n 's/^#define \(CAP_.*\)\s\+\([0-9]\+\).*$/\1 = \2/p' \
# /usr/include/linux/capability.h
CAP_CHOWN = 0
CAP_DAC_OVERRIDE = 1
CAP_DAC_READ_SEARCH = 2
CAP_FOWNER = 3
CAP_FSETID = 4
CAP_KILL = 5
CAP_SETGID = 6
CAP_SETUID = 7
CAP_SETPCAP = 8
CAP_LINUX_IMMUTABLE = 9
CAP_NET_BIND_SERVICE = 10
CAP_NET_BROADCAST = 11
CAP_NET_ADMIN = 12
CAP_NET_RAW = 13
CAP_IPC_LOCK = 14
CAP_IPC_OWNER = 15
CAP_SYS_MODULE = 16
CAP_SYS_RAWIO = 17
CAP_SYS_CHROOT = 18
CAP_SYS_PTRACE = 19
CAP_SYS_PACCT = 20
CAP_SYS_ADMIN = 21
CAP_SYS_BOOT = 22
CAP_SYS_NICE = 23
CAP_SYS_RESOURCE = 24
CAP_SYS_TIME = 25
CAP_SYS_TTY_CONFIG = 26
CAP_MKNOD = 27
CAP_LEASE = 28
CAP_AUDIT_WRITE = 29
CAP_AUDIT_CONTROL = 30
CAP_SETFCAP = 31
CAP_MAC_OVERRIDE = 32
CAP_MAC_ADMIN = 33
CAP_SYSLOG = 34
CAP_WAKE_ALARM = 35
CAP_BLOCK_SUSPEND = 36
uid, gid = 1000, 1000
print("before droping caps")
os.system("cat /proc/{}/status | grep Cap".format(pid))
cap_values = (CAP_NET_BIND_SERVICE, )
cap_values_temp = (CAP_NET_BIND_SERVICE, CAP_SETUID, CAP_SETGID)
ccap_values = ffi.new('cap_value_t[]', cap_values)
ccap_values_temp = ffi.new('cap_value_t[]', cap_values_temp)
#caps = libcap.cap_get_proc()
caps = libcap.cap_init()
print('len cap_values:', len(cap_values))
libcap.cap_set_flag(caps, CAP_PERMITTED,
len(cap_values), ccap_values, CAP_SET)
libcap.cap_set_flag(caps, CAP_PERMITTED,
len(cap_values_temp), ccap_values_temp, CAP_SET)
libcap.cap_set_flag(caps, CAP_EFFECTIVE,
len(cap_values_temp), ccap_values_temp, CAP_SET)
libcap.cap_set_proc(caps)
libcap.cap_free(caps)
print("after dropping caps")
os.system("cat /proc/{}/status | grep Cap".format(pid))
print('result:', libc.prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0))
os.setgroups(os.getgrouplist(pwd.getpwuid(uid)[0], gid))
os.setgid(gid)
os.setuid(uid)
print("after setgid/setuid/setgroups")
os.system("cat /proc/{}/status | grep Cap".format(pid))
#caps = libcap.cap_get_proc()
caps = libcap.cap_init()
libcap.cap_set_flag(caps, CAP_PERMITTED, len(cap_values), ccap_values, CAP_SET)
libcap.cap_set_flag(caps, CAP_EFFECTIVE, len(cap_values), ccap_values, CAP_SET)
libcap.cap_set_proc(caps)
libcap.cap_free(caps)
print("after regaining capabilities")
os.system("cat /proc/{}/status | grep Cap".format(pid))
time.sleep(9999)
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