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# Copyright 1999-2013 Gentoo Foundation
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# Distributed under the terms of the GNU General Public License v2
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# $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.20 2013/04/09 23:43:53 zorry Exp $
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# @ECLASS: pax-utils.eclass
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# @MAINTAINER:
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# The Gentoo Linux Hardened Team <hardened@gentoo.org>
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# @AUTHOR:
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# Original Author: Kevin F. Quinn <kevquinn@gentoo.org>
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# Modifications for bug #365825, @ ECLASS markup: Anthony G. Basile <blueness@gentoo.org>
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# Modifications for bug #431092: Anthony G. Basile <blueness@gentoo.org>
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# @BLURB: functions to provide pax markings
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# @DESCRIPTION:
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#
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# This eclass provides support for manipulating PaX markings on ELF binaries,
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# whether the system is using legacy PT_PAX markings or the newer XATTR_PAX.
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# The eclass wraps the use of paxctl-ng, paxctl, set/getattr and scanelf utilities,
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# deciding which to use depending on what's installed on the build host, and
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# whether we're working with PT_PAX, XATTR_PAX or both.
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#
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# To control what markings are made, set PAX_MARKINGS in /etc/portage/make.conf
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# to contain either "PT", "XT" or "none". The default is to attempt both
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# PT_PAX and XATTR_PAX.
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if [[ ${___ECLASS_ONCE_PAX_UTILS} != "recur -_+^+_- spank" ]] ; then
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___ECLASS_ONCE_PAX_UTILS="recur -_+^+_- spank"
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# @ECLASS-VARIABLE: PAX_MARKINGS
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# @DESCRIPTION:
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# Control which markings are made:
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# PT = PT_PAX markings, XT = XATTR_PAX markings
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# Default to PT markings.
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PAX_MARKINGS=${PAX_MARKINGS:="PT"}
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# @FUNCTION: pax-mark
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# @USAGE: <flags> {<ELF files>}
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# @RETURN: Shell true if we succeed, shell false otherwise
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# @DESCRIPTION:
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# Marks <ELF files> with provided PaX <flags>
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#
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# Flags are passed directly to the utilities unchanged
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#
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# p: disable PAGEEXEC P: enable PAGEEXEC
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# e: disable EMUTRAMP E: enable EMUTRAMP
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# m: disable MPROTECT M: enable MPROTECT
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# r: disable RANDMMAP R: enable RANDMMAP
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# s: disable SEGMEXEC S: enable SEGMEXEC
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#
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# Default flags are 'PeMRS', which are the most restrictive settings. Refer
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# to http://pax.grsecurity.net/ for details on what these flags are all about.
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#
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# Please confirm any relaxation of restrictions with the Gentoo Hardened team.
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# Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on
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# the bug report.
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pax-mark() {
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local f # loop over paxables
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local flags # pax flags
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local pt_fail=0 pt_failures="" # record PT_PAX failures
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local xt_fail=0 xt_failures="" # record xattr PAX marking failures
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local ret=0 # overal return code of this function
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# Only the actual PaX flags and z are accepted
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# 1. The leading '-' is optional
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# 2. -C -c only make sense for paxctl, but are unnecessary
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# because we progressively do -q -qc -qC
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# 3. z is allowed for the default
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flags="${1//[!zPpEeMmRrSs]}"
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[[ "${flags}" ]] || return 0
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shift
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# z = default. For XATTR_PAX, the default is no xattr field at all
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local dodefault=""
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[[ "${flags//[!z]}" ]] && dodefault="yes"
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if has PT ${PAX_MARKINGS}; then
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#First try paxctl -> this might try to create/convert program headers
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if type -p paxctl > /dev/null; then
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einfo "PT PaX marking -${flags} with paxctl"
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_pax_list_files einfo "$@"
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for f in "$@"; do
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# First, try modifying the existing PAX_FLAGS header
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paxctl -q${flags} "${f}" && continue
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# Second, try creating a PT_PAX header (works on ET_EXEC)
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# Even though this is less safe, most exes need it, eg bug #463170
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paxctl -qC${flags} "${f}" && continue
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# Third, try stealing the (unused under PaX) PT_GNU_STACK header
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paxctl -qc${flags} "${f}" && continue
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pt_fail=1
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pt_failures="${pt_failures} ${f}"
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done
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#Next try paxctl-ng -> this will not create/convert any program headers
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elif type -p paxctl-ng > /dev/null && paxctl-ng -L ; then
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einfo "PT PaX marking -${flags} with paxctl-ng"
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flags="${flags//z}"
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_pax_list_files einfo "$@"
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for f in "$@"; do
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[[ ${dodefault} == "yes" ]] && paxctl-ng -L -z "${f}"
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[[ "${flags}" ]] || continue
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paxctl-ng -L -${flags} "${f}" && continue
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pt_fail=1
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pt_failures="${pt_failures} ${f}"
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done
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#Finally fall back on scanelf
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elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
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einfo "Fallback PaX marking -${flags} with scanelf"
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_pax_list_files einfo "$@"
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scanelf -Xxz ${flags} "$@"
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#We failed to set PT_PAX flags
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elif [[ ${PAX_MARKINGS} != "none" ]]; then
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pt_failures="$*"
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pt_fail=1
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fi
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if [[ ${pt_fail} == 1 ]]; then
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elog "Failed to set PT_PAX markings -${flags} for:"
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_pax_list_files elog ${pt_failures}
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ret=1
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fi
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fi
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if has XT ${PAX_MARKINGS}; then
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flags="${flags//z}"
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#First try paxctl-ng
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if type -p paxctl-ng > /dev/null && paxctl-ng -l ; then
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einfo "XT PaX marking -${flags} with paxctl-ng"
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_pax_list_files einfo "$@"
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for f in "$@"; do
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[[ ${dodefault} == "yes" ]] && paxctl-ng -d "${f}"
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[[ "${flags}" ]] || continue
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paxctl-ng -l -${flags} "${f}" && continue
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xt_fail=1
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xt_failures="${tx_failures} ${f}"
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done
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#Next try setfattr
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elif type -p setfattr > /dev/null; then
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[[ "${flags//[!Ee]}" ]] || flags+="e" # bug 447150
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einfo "XT PaX marking -${flags} with setfattr"
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_pax_list_files einfo "$@"
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for f in "$@"; do
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[[ ${dodefault} == "yes" ]] && setfattr -x "user.pax.flags" "${f}"
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setfattr -n "user.pax.flags" -v "${flags}" "${f}" && continue
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xt_fail=1
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xt_failures="${tx_failures} ${f}"
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done
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#We failed to set XATTR_PAX flags
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elif [[ ${PAX_MARKINGS} != "none" ]]; then
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xt_failures="$*"
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xt_fail=1
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fi
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if [[ ${xt_fail} == 1 ]]; then
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elog "Failed to set XATTR_PAX markings -${flags} for:"
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_pax_list_files elog ${xt_failures}
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ret=1
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fi
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fi
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# [[ ${ret} == 1 ]] && elog "Executables may be killed by PaX kernels."
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return ${ret}
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}
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# @FUNCTION: list-paxables
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# @USAGE: {<files>}
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# @RETURN: Subset of {<files>} which are ELF executables or shared objects
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# @DESCRIPTION:
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# Print to stdout all of the <files> that are suitable to have PaX flag
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# markings, i.e., filter out the ELF executables or shared objects from a list
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# of files. This is useful for passing wild-card lists to pax-mark, although
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# in general it is preferable for ebuilds to list precisely which ELFS are to
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# be marked. Often not all the ELF installed by a package need remarking.
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# @EXAMPLE:
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# pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
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list-paxables() {
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file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//'
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}
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# @FUNCTION: host-is-pax
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# @RETURN: Shell true if the build process is PaX enabled, shell false otherwise
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# @DESCRIPTION:
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# This is intended for use where the build process must be modified conditionally
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# depending on whether the host is PaX enabled or not. It is not intedened to
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# determine whether the final binaries need PaX markings. Note: if procfs is
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# not mounted on /proc, this returns shell false (e.g. Gentoo/FBSD).
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host-is-pax() {
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grep -qs ^PaX: /proc/self/status
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}
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# INTERNAL FUNCTIONS
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# ------------------
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#
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# These functions are for use internally by the eclass - do not use
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# them elsewhere as they are not supported (i.e. they may be removed
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# or their function may change arbitratily).
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# Display a list of things, one per line, indented a bit, using the
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# display command in $1.
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_pax_list_files() {
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local f cmd
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cmd=$1
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shift
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for f in "$@"; do
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${cmd} " ${f}"
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done
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}
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fi
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