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Revision 1.12 - (hide annotations) (download)
Sat Jul 2 17:03:51 2011 UTC (3 years, 4 months ago) by blueness
Branch: MAIN
Changes since 1.11: +24 -10 lines
Make dependency on pax-utils and paxctl explicit

1 blueness 1.11 # Copyright 1999-2011 Gentoo Foundation
2 kevquinn 1.1 # Distributed under the terms of the GNU General Public License v2
3 blueness 1.12 # $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.11 2011/05/22 01:01:40 blueness Exp $
4 kevquinn 1.1
5 blueness 1.11 # @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 blueness 1.12 IUSE="hardened"
29    
30     DEPEND="hardened? ( app-misc/pax-utils
31     sys-apps/paxctl )"
32    
33 blueness 1.11 # Default to PT markings.
34     PAX_MARKINGS=${PAX_MARKINGS:="PT"}
35    
36     # @FUNCTION: pax-mark
37     # @USAGE: <flags> {<ELF files>}
38     # @RETURN: Shell true if we succeed, shell false otherwise
39     # @DESCRIPTION:
40     # Marks <ELF files> with provided PaX <flags>
41 kevquinn 1.4 #
42 blueness 1.11 # Flags are passed directly to the utilities unchanged. Possible flags at the
43     # time of writing, taken from /sbin/paxctl, are:
44 kevquinn 1.4 #
45     # p: disable PAGEEXEC P: enable PAGEEXEC
46     # e: disable EMUTRMAP E: enable EMUTRMAP
47     # m: disable MPROTECT M: enable MPROTECT
48     # r: disable RANDMMAP R: enable RANDMMAP
49     # s: disable SEGMEXEC S: enable SEGMEXEC
50     #
51 blueness 1.11 # Default flags are 'PeMRS', which are the most restrictive settings. Refer
52     # to http://pax.grsecurity.net/ for details on what these flags are all about.
53     # Do not use the obsolete flag 'x'/'X' which has been deprecated.
54     #
55     # Please confirm any relaxation of restrictions with the Gentoo Hardened team.
56     # Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on
57     # the bug report.
58 kevquinn 1.1 pax-mark() {
59 blueness 1.12 # It doesn't make sense to pax-mark on non-hardened systems
60     # so we'll just do nothing.
61     use hardened || return 0;
62    
63 kevquinn 1.6 local f flags fail=0 failures="" zero_load_alignment
64 kevquinn 1.4 # Ignore '-' characters - in particular so that it doesn't matter if
65     # the caller prefixes with -
66 kevquinn 1.3 flags=${1//-}
67 kevquinn 1.2 shift
68 blueness 1.11 # Try paxctl, then scanelf. paxctl is preferred.
69 kevquinn 1.4 if type -p paxctl > /dev/null && hasq PT ${PAX_MARKINGS}; then
70     # Try paxctl, the upstream supported tool.
71 kevquinn 1.7 elog "PT PaX marking -${flags}"
72 kevquinn 1.5 _pax_list_files elog "$@"
73 kevquinn 1.4 for f in "$@"; do
74 kevquinn 1.6 # First, try modifying the existing PAX_FLAGS header
75 kevquinn 1.5 paxctl -q${flags} "${f}" && continue
76 kevquinn 1.6 # Second, try stealing the (unused under PaX) PT_GNU_STACK header
77 kevquinn 1.5 paxctl -qc${flags} "${f}" && continue
78 kevquinn 1.6 # Third, try pulling the base down a page, to create space and
79     # insert a PT_GNU_STACK header (works on ET_EXEC)
80 kevquinn 1.5 paxctl -qC${flags} "${f}" && continue
81 blueness 1.12 #
82     # prelink is masked on hardened so we wont use this method.
83     # We're working on a new utiity to try to do the same safely. See
84     # http://git.overlays.gentoo.org/gitweb/?p=proj/elfix.git;a=summary
85     #
86 kevquinn 1.6 # Fourth - check if it loads to 0 (probably an ET_DYN) and if so,
87     # try rebasing with prelink first to give paxctl some space to
88     # grow downwards into.
89 blueness 1.12 #if type -p objdump > /dev/null && type -p prelink > /dev/null; then
90     # zero_load_alignment=$(objdump -p "${f}" | \
91     # grep -E '^[[:space:]]*LOAD[[:space:]]*off[[:space:]]*0x0+[[:space:]]' | \
92     # sed -e 's/.*align\(.*\)/\1/')
93     # if [[ ${zero_load_alignment} != "" ]]; then
94     # prelink -r $(( 2*(${zero_load_alignment}) )) &&
95     # paxctl -qC${flags} "${f}" && continue
96     # fi
97     #fi
98 kevquinn 1.3 fail=1
99     failures="${failures} ${f}"
100     done
101 kevquinn 1.5 elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
102 kevquinn 1.6 # Try scanelf, the Gentoo swiss-army knife ELF utility
103 blueness 1.11 # Currently this sets PT if it can, no option to control what it does.
104 kevquinn 1.7 elog "Fallback PaX marking -${flags}"
105 kevquinn 1.5 _pax_list_files elog "$@"
106     scanelf -Xxz ${flags} "$@"
107     elif [[ ${PAX_MARKINGS} != "none" ]]; then
108 kevquinn 1.4 # Out of options!
109 kevquinn 1.3 failures="$*"
110 kevquinn 1.2 fail=1
111 kevquinn 1.1 fi
112 kevquinn 1.3 if [[ ${fail} == 1 ]]; then
113     ewarn "Failed to set PaX markings -${flags} for:"
114     _pax_list_files ewarn ${failures}
115     ewarn "Executables may be killed by PaX kernels."
116     fi
117 kevquinn 1.2 return ${fail}
118     }
119    
120 blueness 1.11 # @FUNCTION: list-paxables
121     # @USAGE: {<files>}
122     # @RETURN: Subset of {<files>} which are ELF executables or shared objects
123     # @DESCRIPTION:
124     # Print to stdout all of the <files> that are suitable to have PaX flag
125     # markings, i.e., filter out the ELF executables or shared objects from a list
126     # of files. This is useful for passing wild-card lists to pax-mark, although
127     # in general it is preferable for ebuilds to list precisely which ELFS are to
128     # be marked. Often not all the ELF installed by a package need remarking.
129     # @EXAMPLE:
130     # pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
131 kevquinn 1.4 list-paxables() {
132 kevquinn 1.6 file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//'
133 kevquinn 1.4 }
134    
135 blueness 1.11 # @FUNCTION: host-is-pax
136     # @RETURN: Shell true if the build process is PaX enabled, shell false otherwise
137     # @DESCRIPTION:
138     # This is intended for use where the build process must be modified conditionally
139     # depending on whether the host is PaX enabled or not. It is not intedened to
140     # determine whether the final binaries need PaX markings. Note: if procfs is
141     # not mounted on /proc, this returns shell false (e.g. Gentoo/FBSD).
142 kevquinn 1.2 host-is-pax() {
143 kevquinn 1.4 grep -qs ^PaX: /proc/self/status
144     }
145    
146    
147     # INTERNAL FUNCTIONS
148     # ------------------
149     #
150     # These functions are for use internally by the eclass - do not use
151     # them elsewhere as they are not supported (i.e. they may be removed
152     # or their function may change arbitratily).
153    
154     # Display a list of things, one per line, indented a bit, using the
155     # display command in $1.
156     _pax_list_files() {
157     local f cmd
158     cmd=$1
159     shift
160     for f in "$@"; do
161     ${cmd} " ${f}"
162     done
163 kevquinn 1.1 }

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