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1# Copyright 1999-2006 Gentoo Foundation 1# Copyright 1999-2011 Gentoo Foundation
2# Distributed under the terms of the GNU General Public License v2 2# Distributed under the terms of the GNU General Public License v2
3# $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.7 2007/05/07 09:24:16 kevquinn Exp $ 3# $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.18 2012/04/06 18:03:54 blueness Exp $
4 4
5# Author: 5# @ECLASS: pax-utils.eclass
6# @MAINTAINER:
7# The Gentoo Linux Hardened Team <hardened@gentoo.org>
8# @AUTHOR:
6# Kevin F. Quinn <kevquinn@gentoo.org> 9# Original Author: Kevin F. Quinn <kevquinn@gentoo.org>
10# Modifications for bug #365825, @ ECLASS markup: Anthony G. Basile <blueness@gentoo.org>
11# @BLURB: functions to provide pax markings
12# @DESCRIPTION:
13# This eclass provides support for manipulating PaX markings on ELF binaries,
14# wrapping the use of the paxctl and scanelf utilities. It decides which to
15# use depending on what is installed on the build host, preferring paxctl to
16# scanelf. If paxctl is not installed, we fall back to scanelf since it is
17# always present. However, currently scanelf doesn't do all that paxctl can.
7# 18#
8# This eclass provides support for manipulating PaX markings on ELF 19# To control what markings are made, set PAX_MARKINGS in /etc/make.conf to
9# binaries, wrapping the use of the chpaxi, paxctl and scanelf utilities. 20# contain either "PT" or "none". If PAX_MARKINGS is set to "PT", and the
10# Currently it decides which to use depending on what is installed on the 21# necessary utility is installed, the PT_PAX_FLAGS markings will be made. If
11# build host; this may change in the future to use a control variable 22# PAX_MARKINGS is set to "none", no markings will be made.
12# (which would also mean modifying DEPEND to bring in sys-apps/paxctl etc). 23
24if [[ ${___ECLASS_ONCE_PAX_UTILS} != "recur -_+^+_- spank" ]] ; then
25___ECLASS_ONCE_PAX_UTILS="recur -_+^+_- spank"
26
27# Default to PT markings.
28PAX_MARKINGS=${PAX_MARKINGS:="PT"}
29
30# @FUNCTION: pax-mark
31# @USAGE: <flags> {<ELF files>}
32# @RETURN: Shell true if we succeed, shell false otherwise
33# @DESCRIPTION:
34# Marks <ELF files> with provided PaX <flags>
13# 35#
14#
15# CONTROL
16# -------
17#
18# To control what markings are set, assign PAX_MARKINGS in
19# /etc/make.conf to contain the strings "EI" and/or "PT".
20# If EI is present in PAX_MARKINGS (and the chpax utility
21# is present), the legacy 'chpax' style markings will be
22# set. If PT is present in PAX_MARKINGS (and the paxctl
23# utility is present), the 'paxctl' markings will be set.
24# Default is to try to do both. Set it to "NONE" to prevent
25# any markings being made.
26#
27#
28# PROVIDED FUNCTIONS
29# ------------------
30#
31#### pax-mark <flags> {<ELF files>}
32# Marks files <files> with provided PaX flags <flags>
33#
34# Please confirm any relaxation of restrictions with the
35# Gentoo Hardened team; either ask on the gentoo-hardened
36# mailing list, or CC/assign hardened@g.o on a bug.
37#
38# Flags are passed directly to the utilities unchanged. Possible 36# Flags are passed directly to the utilities unchanged. Possible flags at the
39# flags at the time of writing, taken from /sbin/paxctl, are: 37# time of writing, taken from /sbin/paxctl, are:
40# 38#
41# p: disable PAGEEXEC P: enable PAGEEXEC 39# p: disable PAGEEXEC P: enable PAGEEXEC
42# e: disable EMUTRMAP E: enable EMUTRMAP 40# e: disable EMUTRMAP E: enable EMUTRMAP
43# m: disable MPROTECT M: enable MPROTECT 41# m: disable MPROTECT M: enable MPROTECT
44# r: disable RANDMMAP R: enable RANDMMAP 42# r: disable RANDMMAP R: enable RANDMMAP
45# s: disable SEGMEXEC S: enable SEGMEXEC 43# s: disable SEGMEXEC S: enable SEGMEXEC
46# 44#
47# Default flags are 'PeMRS', which are the most restrictive 45# Default flags are 'PeMRS', which are the most restrictive settings. Refer
48# settings. Refer to http://pax.grsecurity.net/ for details 46# to http://pax.grsecurity.net/ for details on what these flags are all about.
49# on what these flags are all about. There is an obsolete 47# Do not use the obsolete flag 'x'/'X' which has been deprecated.
50# flag 'x'/'X' which has been removed from PaX.
51# 48#
52# If chpax is not installed, the legacy EI flags (which are 49# Please confirm any relaxation of restrictions with the Gentoo Hardened team.
53# not strip-safe, and strictly speaking violate the ELF spec) 50# Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on
54# will not be set. If paxctl is not installed, it falls back 51# the bug report.
55# to scanelf. scanelf is always present, but currently doesn't
56# quite do all that paxctl can do.
57# Returns fail if one or more files could not be marked.
58#
59#
60#### list-paxables {<files>}
61# Prints to stdout all of <files> that are suitable to having PaX
62# flags (i.e. filter to just ELF files). Useful for passing wild-card
63# lists of files to pax-mark, although in general it is preferable
64# for ebuilds to list precisely which executables are to be marked.
65# Use like:
66# pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
67#
68#
69#### host-is-pax
70# Returns true if the host has a PaX-enabled kernel, false otherwise.
71# Intended for use where the build process must be modified conditionally
72# in order to satisfy PaX. Note; it is _not_ intended to indicate
73# whether the final executables should satisfy PaX - executables should
74# always be marked appropriately even if they're only going to be
75# installed on a non-PaX system.
76
77inherit eutils
78
79# Default to both EI and PT markings.
80PAX_MARKINGS=${PAX_MARKINGS:="EI PT"}
81
82# pax-mark <flags> {<ELF files>}
83pax-mark() { 52pax-mark() {
84 local f flags fail=0 failures="" zero_load_alignment 53 local f flags fail=0 failures="" zero_load_alignment
85 # Ignore '-' characters - in particular so that it doesn't matter if 54 # Ignore '-' characters - in particular so that it doesn't matter if
86 # the caller prefixes with - 55 # the caller prefixes with -
87 flags=${1//-} 56 flags=${1//-}
88 shift 57 shift
89 # Try chpax, for (deprecated) EI legacy marking.
90 if type -p chpax > /dev/null && hasq EI ${PAX_MARKINGS}; then
91 elog "Legacy EI PaX marking -${flags}"
92 _pax_list_files elog "$@"
93 for f in "$@"; do
94 chpax -${flags} "${f}" && continue
95 fail=1
96 failures="${failures} ${f}"
97 done
98 fi
99 # Try paxctl, then scanelf - paxctl takes precedence 58 # Try paxctl, then scanelf. paxctl is preferred.
100 # over scanelf.
101 if type -p paxctl > /dev/null && hasq PT ${PAX_MARKINGS}; then 59 if type -p paxctl > /dev/null && has PT ${PAX_MARKINGS}; then
102 # Try paxctl, the upstream supported tool. 60 # Try paxctl, the upstream supported tool.
103 elog "PT PaX marking -${flags}" 61 einfo "PT PaX marking -${flags}"
104 _pax_list_files elog "$@" 62 _pax_list_files einfo "$@"
105 for f in "$@"; do 63 for f in "$@"; do
106 # First, try modifying the existing PAX_FLAGS header 64 # First, try modifying the existing PAX_FLAGS header
107 paxctl -q${flags} "${f}" && continue 65 paxctl -q${flags} "${f}" && continue
108 # Second, try stealing the (unused under PaX) PT_GNU_STACK header 66 # Second, try stealing the (unused under PaX) PT_GNU_STACK header
109 paxctl -qc${flags} "${f}" && continue 67 paxctl -qc${flags} "${f}" && continue
110 # Third, try pulling the base down a page, to create space and 68 # Third, try pulling the base down a page, to create space and
111 # insert a PT_GNU_STACK header (works on ET_EXEC) 69 # insert a PT_GNU_STACK header (works on ET_EXEC)
112 paxctl -qC${flags} "${f}" && continue 70 paxctl -qC${flags} "${f}" && continue
71 #
72 # prelink is masked on hardened so we wont use this method.
73 # We're working on a new utiity to try to do the same safely. See
74 # http://git.overlays.gentoo.org/gitweb/?p=proj/elfix.git;a=summary
75 #
113 # Fourth - check if it loads to 0 (probably an ET_DYN) and if so, 76 # Fourth - check if it loads to 0 (probably an ET_DYN) and if so,
114 # try rebasing with prelink first to give paxctl some space to 77 # try rebasing with prelink first to give paxctl some space to
115 # grow downwards into. 78 # grow downwards into.
116 if type -p objdump > /dev/null && type -p prelink > /dev/null; then 79 #if type -p objdump > /dev/null && type -p prelink > /dev/null; then
117 zero_load_alignment=$(objdump -p "${f}" | \ 80 # zero_load_alignment=$(objdump -p "${f}" | \
118 grep -E '^[[:space:]]*LOAD[[:space:]]*off[[:space:]]*0x0+[[:space:]]' | \ 81 # grep -E '^[[:space:]]*LOAD[[:space:]]*off[[:space:]]*0x0+[[:space:]]' | \
119 sed -e 's/.*align\(.*\)/\1/') 82 # sed -e 's/.*align\(.*\)/\1/')
120 if [[ ${zero_load_alignment} != "" ]]; then 83 # if [[ ${zero_load_alignment} != "" ]]; then
121 prelink -r $(( 2*(${zero_load_alignment}) )) && 84 # prelink -r $(( 2*(${zero_load_alignment}) )) &&
122 paxctl -qC${flags} "${f}" && continue 85 # paxctl -qC${flags} "${f}" && continue
123 fi 86 # fi
124 fi 87 #fi
125 fail=1 88 fail=1
126 failures="${failures} ${f}" 89 failures="${failures} ${f}"
127 done 90 done
128 elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then 91 elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
129 # Try scanelf, the Gentoo swiss-army knife ELF utility 92 # Try scanelf, the Gentoo swiss-army knife ELF utility
130 # Currently this sets EI and PT if it can, no option to 93 # Currently this sets PT if it can, no option to control what it does.
131 # control what it does.
132 elog "Fallback PaX marking -${flags}" 94 einfo "Fallback PaX marking -${flags}"
133 _pax_list_files elog "$@" 95 _pax_list_files einfo "$@"
134 scanelf -Xxz ${flags} "$@" 96 scanelf -Xxz ${flags} "$@"
135 elif [[ ${PAX_MARKINGS} != "none" ]]; then 97 elif [[ ${PAX_MARKINGS} != "none" ]]; then
136 # Out of options! 98 # Out of options!
137 failures="$*" 99 failures="$*"
138 fail=1 100 fail=1
143 ewarn "Executables may be killed by PaX kernels." 105 ewarn "Executables may be killed by PaX kernels."
144 fi 106 fi
145 return ${fail} 107 return ${fail}
146} 108}
147 109
148# list-paxables {<files>} 110# @FUNCTION: list-paxables
111# @USAGE: {<files>}
112# @RETURN: Subset of {<files>} which are ELF executables or shared objects
113# @DESCRIPTION:
114# Print to stdout all of the <files> that are suitable to have PaX flag
115# markings, i.e., filter out the ELF executables or shared objects from a list
116# of files. This is useful for passing wild-card lists to pax-mark, although
117# in general it is preferable for ebuilds to list precisely which ELFS are to
118# be marked. Often not all the ELF installed by a package need remarking.
119# @EXAMPLE:
120# pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
149list-paxables() { 121list-paxables() {
150 file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//' 122 file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//'
151} 123}
152 124
153# host-is-pax 125# @FUNCTION: host-is-pax
126# @RETURN: Shell true if the build process is PaX enabled, shell false otherwise
127# @DESCRIPTION:
128# This is intended for use where the build process must be modified conditionally
129# depending on whether the host is PaX enabled or not. It is not intedened to
130# determine whether the final binaries need PaX markings. Note: if procfs is
154# Note: if procfs is not on /proc, this returns False (e.g. Gentoo/FBSD). 131# not mounted on /proc, this returns shell false (e.g. Gentoo/FBSD).
155host-is-pax() { 132host-is-pax() {
156 grep -qs ^PaX: /proc/self/status 133 grep -qs ^PaX: /proc/self/status
157} 134}
158 135
159 136
173 for f in "$@"; do 150 for f in "$@"; do
174 ${cmd} " ${f}" 151 ${cmd} " ${f}"
175 done 152 done
176} 153}
177 154
155fi

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