| 1 |
# Copyright 1999-2011 Gentoo Foundation
|
| 2 |
# Distributed under the terms of the GNU General Public License v2
|
| 3 |
# $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.13 2011/07/03 21:17:10 blueness Exp $
|
| 4 |
|
| 5 |
# @ECLASS: pax-utils.eclass
|
| 6 |
# @MAINTAINER:
|
| 7 |
# Maintained by
|
| 8 |
# The Gentoo Linux Hardened Team <hardened@gentoo.org>
|
| 9 |
# Original Author
|
| 10 |
# Kevin F. Quinn <kevquinn@gentoo.org>
|
| 11 |
# Modifications for bug #365825, @ ECLASS markup
|
| 12 |
# Anthony G. Basile <blueness@gentoo.org>
|
| 13 |
# @BLURB: functions to provide pax markings
|
| 14 |
# @DESCRIPTION:
|
| 15 |
# This eclass provides support for manipulating PaX markings on ELF binaries,
|
| 16 |
# wrapping the use of the paxctl and scanelf utilities. It decides which to
|
| 17 |
# use depending on what is installed on the build host, preferring paxctl to
|
| 18 |
# scanelf. If paxctl is not installed, we fall back to scanelf since it is
|
| 19 |
# always present. However, currently scanelf doesn't do all that paxctl can.
|
| 20 |
#
|
| 21 |
# To control what markings are made, set PAX_MARKINGS in /etc/make.conf to
|
| 22 |
# contain either "PT" or "none". If PAX_MARKINGS is set to "PT", and the
|
| 23 |
# necessary utility is installed, the PT_PAX_FLAGS markings will be made. If
|
| 24 |
# PAX_MARKINGS is set to "none", no markings will be made.
|
| 25 |
|
| 26 |
inherit eutils
|
| 27 |
|
| 28 |
# Default to PT markings.
|
| 29 |
PAX_MARKINGS=${PAX_MARKINGS:="PT"}
|
| 30 |
|
| 31 |
# @FUNCTION: pax-mark
|
| 32 |
# @USAGE: <flags> {<ELF files>}
|
| 33 |
# @RETURN: Shell true if we succeed, shell false otherwise
|
| 34 |
# @DESCRIPTION:
|
| 35 |
# Marks <ELF files> with provided PaX <flags>
|
| 36 |
#
|
| 37 |
# Flags are passed directly to the utilities unchanged. Possible flags at the
|
| 38 |
# time of writing, taken from /sbin/paxctl, are:
|
| 39 |
#
|
| 40 |
# p: disable PAGEEXEC P: enable PAGEEXEC
|
| 41 |
# e: disable EMUTRMAP E: enable EMUTRMAP
|
| 42 |
# m: disable MPROTECT M: enable MPROTECT
|
| 43 |
# r: disable RANDMMAP R: enable RANDMMAP
|
| 44 |
# s: disable SEGMEXEC S: enable SEGMEXEC
|
| 45 |
#
|
| 46 |
# Default flags are 'PeMRS', which are the most restrictive settings. Refer
|
| 47 |
# to http://pax.grsecurity.net/ for details on what these flags are all about.
|
| 48 |
# Do not use the obsolete flag 'x'/'X' which has been deprecated.
|
| 49 |
#
|
| 50 |
# Please confirm any relaxation of restrictions with the Gentoo Hardened team.
|
| 51 |
# Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on
|
| 52 |
# the bug report.
|
| 53 |
pax-mark() {
|
| 54 |
local f flags fail=0 failures="" zero_load_alignment
|
| 55 |
# Ignore '-' characters - in particular so that it doesn't matter if
|
| 56 |
# the caller prefixes with -
|
| 57 |
flags=${1//-}
|
| 58 |
shift
|
| 59 |
# Try paxctl, then scanelf. paxctl is preferred.
|
| 60 |
if type -p paxctl > /dev/null && has PT ${PAX_MARKINGS}; then
|
| 61 |
# Try paxctl, the upstream supported tool.
|
| 62 |
elog "PT PaX marking -${flags}"
|
| 63 |
_pax_list_files elog "$@"
|
| 64 |
for f in "$@"; do
|
| 65 |
# First, try modifying the existing PAX_FLAGS header
|
| 66 |
paxctl -q${flags} "${f}" && continue
|
| 67 |
# Second, try stealing the (unused under PaX) PT_GNU_STACK header
|
| 68 |
paxctl -qc${flags} "${f}" && continue
|
| 69 |
# Third, try pulling the base down a page, to create space and
|
| 70 |
# insert a PT_GNU_STACK header (works on ET_EXEC)
|
| 71 |
paxctl -qC${flags} "${f}" && continue
|
| 72 |
#
|
| 73 |
# prelink is masked on hardened so we wont use this method.
|
| 74 |
# We're working on a new utiity to try to do the same safely. See
|
| 75 |
# http://git.overlays.gentoo.org/gitweb/?p=proj/elfix.git;a=summary
|
| 76 |
#
|
| 77 |
# Fourth - check if it loads to 0 (probably an ET_DYN) and if so,
|
| 78 |
# try rebasing with prelink first to give paxctl some space to
|
| 79 |
# grow downwards into.
|
| 80 |
#if type -p objdump > /dev/null && type -p prelink > /dev/null; then
|
| 81 |
# zero_load_alignment=$(objdump -p "${f}" | \
|
| 82 |
# grep -E '^[[:space:]]*LOAD[[:space:]]*off[[:space:]]*0x0+[[:space:]]' | \
|
| 83 |
# sed -e 's/.*align\(.*\)/\1/')
|
| 84 |
# if [[ ${zero_load_alignment} != "" ]]; then
|
| 85 |
# prelink -r $(( 2*(${zero_load_alignment}) )) &&
|
| 86 |
# paxctl -qC${flags} "${f}" && continue
|
| 87 |
# fi
|
| 88 |
#fi
|
| 89 |
fail=1
|
| 90 |
failures="${failures} ${f}"
|
| 91 |
done
|
| 92 |
elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
|
| 93 |
# Try scanelf, the Gentoo swiss-army knife ELF utility
|
| 94 |
# Currently this sets PT if it can, no option to control what it does.
|
| 95 |
elog "Fallback PaX marking -${flags}"
|
| 96 |
_pax_list_files elog "$@"
|
| 97 |
scanelf -Xxz ${flags} "$@"
|
| 98 |
elif [[ ${PAX_MARKINGS} != "none" ]]; then
|
| 99 |
# Out of options!
|
| 100 |
failures="$*"
|
| 101 |
fail=1
|
| 102 |
fi
|
| 103 |
if [[ ${fail} == 1 ]]; then
|
| 104 |
ewarn "Failed to set PaX markings -${flags} for:"
|
| 105 |
_pax_list_files ewarn ${failures}
|
| 106 |
ewarn "Executables may be killed by PaX kernels."
|
| 107 |
fi
|
| 108 |
return ${fail}
|
| 109 |
}
|
| 110 |
|
| 111 |
# @FUNCTION: list-paxables
|
| 112 |
# @USAGE: {<files>}
|
| 113 |
# @RETURN: Subset of {<files>} which are ELF executables or shared objects
|
| 114 |
# @DESCRIPTION:
|
| 115 |
# Print to stdout all of the <files> that are suitable to have PaX flag
|
| 116 |
# markings, i.e., filter out the ELF executables or shared objects from a list
|
| 117 |
# of files. This is useful for passing wild-card lists to pax-mark, although
|
| 118 |
# in general it is preferable for ebuilds to list precisely which ELFS are to
|
| 119 |
# be marked. Often not all the ELF installed by a package need remarking.
|
| 120 |
# @EXAMPLE:
|
| 121 |
# pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
|
| 122 |
list-paxables() {
|
| 123 |
file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//'
|
| 124 |
}
|
| 125 |
|
| 126 |
# @FUNCTION: host-is-pax
|
| 127 |
# @RETURN: Shell true if the build process is PaX enabled, shell false otherwise
|
| 128 |
# @DESCRIPTION:
|
| 129 |
# This is intended for use where the build process must be modified conditionally
|
| 130 |
# depending on whether the host is PaX enabled or not. It is not intedened to
|
| 131 |
# determine whether the final binaries need PaX markings. Note: if procfs is
|
| 132 |
# not mounted on /proc, this returns shell false (e.g. Gentoo/FBSD).
|
| 133 |
host-is-pax() {
|
| 134 |
grep -qs ^PaX: /proc/self/status
|
| 135 |
}
|
| 136 |
|
| 137 |
|
| 138 |
# INTERNAL FUNCTIONS
|
| 139 |
# ------------------
|
| 140 |
#
|
| 141 |
# These functions are for use internally by the eclass - do not use
|
| 142 |
# them elsewhere as they are not supported (i.e. they may be removed
|
| 143 |
# or their function may change arbitratily).
|
| 144 |
|
| 145 |
# Display a list of things, one per line, indented a bit, using the
|
| 146 |
# display command in $1.
|
| 147 |
_pax_list_files() {
|
| 148 |
local f cmd
|
| 149 |
cmd=$1
|
| 150 |
shift
|
| 151 |
for f in "$@"; do
|
| 152 |
${cmd} " ${f}"
|
| 153 |
done
|
| 154 |
}
|
| 155 |
|
Parent Directory
| 
Revision Log