| # Copyright 1999-2015 Gentoo Foundation |
| # Distributed under the terms of the GNU General Public License v2 |
| # $Id$ |
| |
| # @ECLASS: pax-utils.eclass |
| # @MAINTAINER: |
| # The Gentoo Linux Hardened Team <hardened@gentoo.org> |
| # @AUTHOR: |
| # Original Author: Kevin F. Quinn <kevquinn@gentoo.org> |
| # Modifications for bugs #365825, #431092, #520198, @ ECLASS markup: Anthony G. Basile <blueness@gentoo.org> |
| # @BLURB: functions to provide PaX markings for hardened kernels |
| # @DESCRIPTION: |
| # |
| # This eclass provides support for manipulating PaX markings on ELF binaries, |
| # whether the system is using legacy PT_PAX markings or the newer XATTR_PAX. |
| # The eclass wraps the use of paxctl-ng, paxctl, set/getattr and scanelf utilities, |
| # deciding which to use depending on what's installed on the build host, and |
| # whether we're working with PT_PAX, XATTR_PAX or both. |
| # |
| # To control what markings are made, set PAX_MARKINGS in /etc/portage/make.conf |
| # to contain either "PT", "XT" or "none". The default is to attempt both |
| # PT_PAX and XATTR_PAX. |
| |
| if [[ -z ${_PAX_UTILS_ECLASS} ]]; then |
| _PAX_UTILS_ECLASS=1 |
| |
| # @ECLASS-VARIABLE: PAX_MARKINGS |
| # @DESCRIPTION: |
| # Control which markings are made: |
| # PT = PT_PAX markings, XT = XATTR_PAX markings |
| # Default to PT markings. |
| PAX_MARKINGS=${PAX_MARKINGS:="PT XT"} |
| |
| # @FUNCTION: pax-mark |
| # @USAGE: <flags> <ELF files> |
| # @RETURN: Shell true if we succeed, shell false otherwise |
| # @DESCRIPTION: |
| # Marks <ELF files> with provided PaX <flags> |
| # |
| # Flags are passed directly to the utilities unchanged. |
| # |
| # @CODE |
| # p: disable PAGEEXEC P: enable PAGEEXEC |
| # e: disable EMUTRAMP E: enable EMUTRAMP |
| # m: disable MPROTECT M: enable MPROTECT |
| # r: disable RANDMMAP R: enable RANDMMAP |
| # s: disable SEGMEXEC S: enable SEGMEXEC |
| # @CODE |
| # |
| # Default flags are 'PeMRS', which are the most restrictive settings. Refer |
| # to http://pax.grsecurity.net/ for details on what these flags are all about. |
| # |
| # Please confirm any relaxation of restrictions with the Gentoo Hardened team. |
| # Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on |
| # the bug report. |
| pax-mark() { |
| local f # loop over paxables |
| local flags # pax flags |
| local ret=0 # overall return code of this function |
| |
| # Only the actual PaX flags and z are accepted |
| # 1. The leading '-' is optional |
| # 2. -C -c only make sense for paxctl, but are unnecessary |
| # because we progressively do -q -qc -qC |
| # 3. z is allowed for the default |
| |
| flags="${1//[!zPpEeMmRrSs]}" |
| [[ "${flags}" ]] || return 0 |
| shift |
| |
| # z = default. For XATTR_PAX, the default is no xattr field at all |
| local dodefault="" |
| [[ "${flags//[!z]}" ]] && dodefault="yes" |
| |
| if has PT ${PAX_MARKINGS}; then |
| # Uncomment to list all files to be marked |
| # _pax_list_files einfo "$@" |
| for f in "$@"; do |
| |
| # First try paxctl -> this might try to create/convert program headers. |
| if type -p paxctl >/dev/null; then |
| einfo "PT_PAX marking -${flags} ${f} with paxctl" |
| # First, try modifying the existing PAX_FLAGS header. |
| paxctl -q${flags} "${f}" >/dev/null 2>&1 && continue |
| # Second, try creating a PT_PAX header (works on ET_EXEC). |
| # Even though this is less safe, most exes need it. #463170 |
| paxctl -qC${flags} "${f}" >/dev/null 2>&1 && continue |
| # Third, try stealing the (unused under PaX) PT_GNU_STACK header |
| paxctl -qc${flags} "${f}" >/dev/null 2>&1 && continue |
| fi |
| |
| # Next try paxctl-ng -> this will not create/convert any program headers. |
| if type -p paxctl-ng >/dev/null && paxctl-ng -L ; then |
| einfo "PT_PAX marking -${flags} ${f} with paxctl-ng" |
| flags="${flags//z}" |
| [[ ${dodefault} == "yes" ]] && paxctl-ng -L -z "${f}" >/dev/null 2>&1 |
| [[ "${flags}" ]] || continue |
| paxctl-ng -L -${flags} "${f}" >/dev/null 2>&1 && continue |
| fi |
| |
| # Finally fall back on scanelf. |
| if type -p scanelf >/dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then |
| einfo "PT_PAX marking -${flags} ${f} with scanelf" |
| scanelf -Xxz ${flags} "$f" >/dev/null 2>&1 |
| # We failed to set PT_PAX flags. |
| elif [[ ${PAX_MARKINGS} != "none" ]]; then |
| elog "Failed to set PT_PAX markings -${flags} ${f}." |
| ret=1 |
| fi |
| done |
| fi |
| |
| if has XT ${PAX_MARKINGS}; then |
| # Uncomment to list all files to be marked |
| # _pax_list_files einfo "$@" |
| flags="${flags//z}" |
| for f in "$@"; do |
| |
| # First try paxctl-ng. |
| if type -p paxctl-ng >/dev/null && paxctl-ng -l ; then |
| einfo "XATTR_PAX marking -${flags} ${f} with paxctl-ng" |
| [[ ${dodefault} == "yes" ]] && paxctl-ng -d "${f}" >/dev/null 2>&1 |
| [[ "${flags}" ]] || continue |
| paxctl-ng -l -${flags} "${f}" >/dev/null 2>&1 && continue |
| fi |
| |
| # Next try setfattr. |
| if type -p setfattr >/dev/null; then |
| [[ "${flags//[!Ee]}" ]] || flags+="e" # bug 447150 |
| einfo "XATTR_PAX marking -${flags} ${f} with setfattr" |
| [[ ${dodefault} == "yes" ]] && setfattr -x "user.pax.flags" "${f}" >/dev/null 2>&1 |
| setfattr -n "user.pax.flags" -v "${flags}" "${f}" >/dev/null 2>&1 && continue |
| fi |
| |
| # We failed to set XATTR_PAX flags. |
| if [[ ${PAX_MARKINGS} != "none" ]]; then |
| elog "Failed to set XATTR_PAX markings -${flags} ${f}." |
| ret=1 |
| fi |
| done |
| fi |
| |
| # [[ ${ret} == 1 ]] && elog "Executables may be killed by PaX kernels." |
| |
| return ${ret} |
| } |
| |
| # @FUNCTION: list-paxables |
| # @USAGE: <files> |
| # @RETURN: Subset of <files> which are ELF executables or shared objects |
| # @DESCRIPTION: |
| # Print to stdout all of the <files> that are suitable to have PaX flag |
| # markings, i.e., filter out the ELF executables or shared objects from a list |
| # of files. This is useful for passing wild-card lists to pax-mark, although |
| # in general it is preferable for ebuilds to list precisely which ELFS are to |
| # be marked. Often not all the ELF installed by a package need remarking. |
| # @EXAMPLE: |
| # pax-mark -m $(list-paxables ${S}/{,usr/}bin/*) |
| list-paxables() { |
| file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//' |
| } |
| |
| # @FUNCTION: host-is-pax |
| # @RETURN: Shell true if the build process is PaX enabled, shell false otherwise |
| # @DESCRIPTION: |
| # This is intended for use where the build process must be modified conditionally |
| # depending on whether the host is PaX enabled or not. It is not indented to |
| # determine whether the final binaries need PaX markings. Note: if procfs is |
| # not mounted on /proc, this returns shell false (e.g. Gentoo/FreeBSD). |
| host-is-pax() { |
| grep -qs ^PaX: /proc/self/status |
| } |
| |
| |
| # INTERNAL FUNCTIONS |
| # ------------------ |
| # |
| # These functions are for use internally by the eclass - do not use |
| # them elsewhere as they are not supported (i.e. they may be removed |
| # or their function may change arbitrarily). |
| |
| # Display a list of things, one per line, indented a bit, using the |
| # display command in $1. |
| _pax_list_files() { |
| local f cmd |
| cmd=$1 |
| shift |
| for f in "$@"; do |
| ${cmd} " ${f}" |
| done |
| } |
| |
| fi |