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#!/usr/bin/env python3
import os.path
import sys
# Files in /dev and /sys seem to vary between Linux systems. Thus, try a few
# candidates and use the first one that exists. What we want is a file with
# permissions root:root -rw------- that’s in a directory readable and
# executable by unprivileged users, so we know we’re testing permissions on
# the file rather than any of its containing directories. This may help for
# finding such a file in /sys:
#
# $ find /sys -type f -a -perm 600 -ls
#
sys_file = None
for f in ("/sys/devices/cpu/rdpmc",
"/sys/kernel/mm/page_idle/bitmap",
"/sys/module/nf_conntrack_ipv4/parameters/hashsize",
"/sys/kernel/slab/request_sock_TCP/red_zone"):
if (os.path.exists(f)):
sys_file = f
break
if (sys_file is None):
print("ERROR\tno test candidates in /sys exist")
sys.exit(1)
dev_file = None
for f in ("/dev/cpu_dma_latency", "/dev/mem"):
if (os.path.exists(f)):
dev_file = f
break
if (dev_file is None):
print("ERROR\tno test candidates in /dev exist")
sys.exit(1)
problem_ct = 0
for f in (dev_file, "/proc/kcore", sys_file):
try:
open(f, "rb").read(1)
print("RISK\t%s: read allowed" % f)
problem_ct += 1
except PermissionError:
print("SAFE\t%s: read not allowed" % f)
except OSError as x:
print("ERROR\t%s: exception: %s" % (f, x))
problem_ct += 1
sys.exit(problem_ct != 0)
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