selinux-refpolicy/support/genhomedircon.py
Christian Göttsche 627a453910 genhomedircon: improve error messages for min uid search
Only grep if the files exist.
grep returns 1 on no match, check against 1 instead of 256.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
2021-01-31 21:53:33 +01:00

324 lines
10 KiB
Python

#!/usr/bin/env python3
# Copyright (C) 2004 Tresys Technology, LLC
# see file 'COPYING' for use and warranty information
#
# genhomedircon - this script is used to generate file context
# configuration entries for user home directories based on their
# default roles and is run when building the policy. Specifically, we
# replace HOME_ROOT, HOME_DIR, and ROLE macros in .fc files with
# generic and user-specific values.
#
# Based off original script by Dan Walsh, <dwalsh@redhat.com>
#
# ASSUMPTIONS:
#
# The file CONTEXTDIR/files/homedir_template exists. This file is used to
# set up the home directory context for each real user.
#
# If a user has more than one role in CONTEXTDIR/local.users, genhomedircon uses
# the first role in the list.
#
# If a user is not listed in CONTEXTDIR/local.users, he will default to user_u, role user
#
# "Real" users (as opposed to system users) are those whose UID is greater than
# or equal STARTING_UID (usually 500) and whose login is not a member of
# EXCLUDE_LOGINS. Users who are explicitly defined in CONTEXTDIR/local.users
# are always "real" (including root, in the default configuration).
#
#
# Old ASSUMPTIONS:
#
# If a user has more than one role in FILECONTEXTDIR/users, genhomedircon uses
# the first role in the list.
#
# If a user is not listed in FILECONTEXTDIR/users, genhomedircon assumes that
# the user's home dir will be found in one of the HOME_ROOTs.
#
# "Real" users (as opposed to system users) are those whose UID is greater than
# or equal STARTING_UID (usually 500) and whose login is not a member of
# EXCLUDE_LOGINS. Users who are explicitly defined in FILECONTEXTDIR/users
# are always "real" (including root, in the default configuration).
#
import sys, pwd, getopt, re, os
from subprocess import getstatusoutput
EXCLUDE_LOGINS=["/sbin/nologin", "/bin/false"]
def getStartingUID():
starting_uid = 99999
rc=getstatusoutput("grep -h '^UID_MIN' /etc/login.defs")
if rc[0] == 0:
uid_min = re.sub("^UID_MIN[^0-9]*", "", rc[1])
#stip any comment from the end of the line
uid_min = uid_min.split("#")[0]
uid_min = uid_min.strip()
if int(uid_min) < starting_uid:
starting_uid = int(uid_min)
rc=getstatusoutput("grep -h '^LU_UIDNUMBER' /etc/libuser.conf")
if rc[0] == 0:
lu_uidnumber = re.sub("^LU_UIDNUMBER[^0-9]*", "", rc[1])
#stip any comment from the end of the line
lu_uidnumber = re.sub("[ \t].*", "", lu_uidnumber)
lu_uidnumber = lu_uidnumber.split("#")[0]
lu_uidnumber = lu_uidnumber.strip()
if int(lu_uidnumber) < starting_uid:
starting_uid = int(lu_uidnumber)
if starting_uid == 99999:
starting_uid = 500
return starting_uid
def getDefaultHomeDir():
ret = []
if os.path.isfile('/etc/default/useradd'):
rc=getstatusoutput("grep -h '^HOME' /etc/default/useradd")
if rc[0] == 0:
homedir = rc[1].split("=")[1]
homedir = homedir.split("#")[0]
homedir = homedir.strip()
if not homedir in ret:
ret.append(homedir)
else:
#rc[0] == 1 means the file was there, we read it, but the grep didn't match
if rc[0] != 1:
sys.stderr.write("(%d): %s\n" % (rc[0], rc[1]))
sys.stderr.write("You do not have access to /etc/default/useradd HOME=\n")
sys.stderr.flush()
if os.path.isfile('/etc/libuser.conf'):
rc=getstatusoutput("grep -h '^LU_HOMEDIRECTORY' /etc/libuser.conf")
if rc[0] == 0:
homedir = rc[1].split("=")[1]
homedir = homedir.split("#")[0]
homedir = homedir.strip()
if not homedir in ret:
ret.append(homedir)
else:
#rc[0] == 1 means the file was there, we read it, but the grep didn't match
if rc[0] != 1:
sys.stderr.write("(%d): %s\n" % (rc[0], rc[1]))
sys.stderr.write("You do not have access to /etc/libuser.conf LU_HOMEDIRECTORY=\n")
sys.stderr.flush()
if ret == []:
ret.append("/home")
return ret
def getSELinuxType(directory):
rc=getstatusoutput("grep ^SELINUXTYPE= %s/config" % directory)
if rc[0]==0:
return rc[1].split("=")[-1].strip()
return "targeted"
def usage(error = ""):
if error != "":
sys.stderr.write("%s\n" % error)
sys.stderr.write("Usage: %s [ -d selinuxdir ] [-n | --nopasswd] [-t selinuxtype ]\n" % sys.argv[0])
sys.stderr.flush()
sys.exit(1)
def warning(warning = ""):
sys.stderr.write("%s\n" % warning)
sys.stderr.flush()
def errorExit(error):
sys.stderr.write("%s exiting for: " % sys.argv[0])
sys.stderr.write("%s\n" % error)
sys.stderr.flush()
sys.exit(1)
class selinuxConfig:
def __init__(self, selinuxdir="/etc/selinux", setype="targeted", usepwd=1):
self.setype=setype
self.selinuxdir=selinuxdir +"/"
self.contextdir="/contexts"
self.filecontextdir=self.contextdir+"/files"
self.usepwd=usepwd
def getFileContextDir(self):
return self.selinuxdir+self.setype+self.filecontextdir
def getFileContextFile(self):
return self.getFileContextDir()+"/file_contexts"
def getHomeDirTemplate(self):
return self.getFileContextDir()+"/homedir_template"
def getHomeRootContext(self, homedir):
rc=getstatusoutput("grep HOME_ROOT %s | sed -e \"s|^HOME_ROOT|%s|\"" % ( self.getHomeDirTemplate(), homedir))
if rc[0] != 0:
errorExit("sed error (" + str(rc[0]) + "): " + rc[1])
return rc[1]+"\n"
def getUsersFile(self):
return self.selinuxdir+self.setype+"/users/local.users"
def getSystemUsersFile(self):
return self.selinuxdir+self.setype+"/users/system.users"
def heading(self):
ret = "\n#\n#\n# User-specific file contexts, generated via %s\n" % sys.argv[0]
ret += "# edit %s to change file_context\n#\n#\n" % self.getUsersFile()
return ret
def getUsers(self):
users=""
rc = getstatusoutput('grep "^user" %s' % self.getSystemUsersFile())
if rc[0] == 0:
users+=rc[1]+"\n"
rc = getstatusoutput("grep ^user %s" % self.getUsersFile())
if rc[0] == 0:
users+=rc[1]
udict = {}
if users != "":
ulist = users.split("\n")
for u in ulist:
user = u.split()
try:
if len(user)==0 or user[1] == "user_u" or user[1] == "system_u":
continue
# !!! chooses first role in the list to use in the file context !!!
role = user[3]
if role == "{":
role = user[4]
role = role.split("_r")[0]
pwdentry = pwd.getpwnam(user[1])
home = pwdentry[5]
if home == "/":
continue
prefs = {}
prefs["role"] = role
prefs["home"] = home
prefs["name"] = pwdentry[0]
prefs["uid"] = pwdentry[2]
udict[user[1]] = prefs
except KeyError:
sys.stderr.write("The user \"%s\" is not present in the passwd file, skipping...\n" % user[1])
return udict
def getHomeDirContext(self, seuser, home, role, username, userid):
ret = "\n\n#\n# Context for user %s\n#\n\n" % seuser
rc = getstatusoutput("grep -E '^HOME_DIR|%%{USERID}|%%{USERNAME}' %s | sed"
" -e 's|HOME_DIR|%s|'"
" -e 's|ROLE|%s|'"
" -e 's|system_u|%s|'"
" -e 's|%%{USERID}|%s|'"
" -e 's|%%{USERNAME}|%s|'"
% (self.getHomeDirTemplate(), home, role, seuser, userid, username))
if rc[0] != 0:
errorExit("sed error (" + str(rc[0]) + "): " + rc[1])
return ret + rc[1] + "\n"
def genHomeDirContext(self):
users = self.getUsers()
ret=""
# Fill in HOME and ROLE for users that are defined
for u in users:
ret += self.getHomeDirContext (u, users[u]["home"], users[u]["role"], users[u]["name"], users[u]["uid"])
return ret+"\n"
def checkExists(self, home):
if getstatusoutput("grep -E '^%s[^[:alnum:]_-]' %s" % (home, self.getFileContextFile()))[0] == 0:
return 0
#this works by grepping the file_contexts for
# 1. ^/ makes sure this is not a comment
# 2. prints only the regex in the first column first cut on \t then on space
rc=getstatusoutput("grep \"^/\" %s | cut -f 1 | cut -f 1 -d \" \" " % self.getFileContextFile() )
if rc[0] == 0:
prefix_regex = rc[1].split("\n")
else:
sys.stderr.write("%s\n" % rc[1])
sys.stderr.write("You do not have access to grep/cut/the file contexts\n")
sys.stderr.flush()
exists=1
for regex in prefix_regex:
#match a trailing (/*)? which is actually a bug in rpc_pipefs
regex = re.sub(r"\(/\*\)\?$", "", regex)
#match a trailing .+
regex = re.sub(r"\.+$", "", regex)
#match a trailing .*
regex = re.sub(r"\.\*$", "", regex)
#strip a (/.*)? which matches anything trailing to a /*$ which matches trailing /'s
regex = re.sub(r"\(\/\.\*\)\?", "", regex)
regex = regex + "/*$"
if re.search(regex, home, 0):
exists = 0
break
if exists == 1:
return 1
return 0
def getHomeDirs(self):
homedirs = []
homedirs = homedirs + getDefaultHomeDir()
starting_uid=getStartingUID()
if self.usepwd==0:
return homedirs
ulist = pwd.getpwall()
for u in ulist:
if u[2] >= starting_uid and \
not u[6] in EXCLUDE_LOGINS and \
u[5] != "/" and \
u[5].count("/") > 1:
homedir = u[5][:u[5].rfind("/")]
if not homedir in homedirs:
if self.checkExists(homedir)==0:
warning("%s is already defined in %s,\n%s will not create a new context." % (homedir, self.getFileContextFile(), sys.argv[0]))
else:
homedirs.append(homedir)
homedirs.sort()
return homedirs
def genoutput(self):
ret= self.heading()
for h in self.getHomeDirs():
ret += self.getHomeDirContext ("user_u" , h+'/[^/]+', "user", "[^/]+", "[0-9]+")
ret += self.getHomeRootContext(h)
ret += self.genHomeDirContext()
return ret
def write(self):
try:
fd = open(self.getFileContextDir()+"/file_contexts.homedirs", "w")
fd.write(self.genoutput())
fd.close()
except IOError as error:
sys.stderr.write("%s: %s\n" % ( sys.argv[0], error ))
#
# This script will generate home dir file context
# based off the homedir_template file, entries in the password file, and
#
try:
usepwd=1
directory="/etc/selinux"
setype=None
gopts, cmds = getopt.getopt(sys.argv[1:], 'nd:t:', ['help',
'type=',
'nopasswd',
'dir='])
for o,a in gopts:
if o in ('--type', '-t'):
setype=a
if o in ('--nopasswd', '-n'):
usepwd=0
if o in ('--dir', '-d'):
directory=a
if o == '--help':
usage()
if setype is None:
setype=getSELinuxType(directory)
if len(cmds) != 0:
usage()
selconf=selinuxConfig(directory, setype, usepwd)
selconf.write()
except Exception as error:
errorExit(error)