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Revision 1.11 - (hide annotations) (download)
Sun May 22 01:01:40 2011 UTC (3 years, 7 months ago) by blueness
Branch: MAIN
Changes since 1.10: +62 -89 lines
Removed chpax, see bug #365825

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 1.11 # $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.10 2010/03/09 10:35:33 nyhm 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     # Default to PT markings.
29     PAX_MARKINGS=${PAX_MARKINGS:="PT"}
30    
31     # @FUNCTION: pax-mark
32     # @USAGE: <flags> {<ELF files>}
33     # @RETURN: Shell true if we succeed, shell false otherwise
34     # @DESCRIPTION:
35     # Marks <ELF files> with provided PaX <flags>
36 kevquinn 1.4 #
37 blueness 1.11 # Flags are passed directly to the utilities unchanged. Possible flags at the
38     # time of writing, taken from /sbin/paxctl, are:
39 kevquinn 1.4 #
40     # p: disable PAGEEXEC P: enable PAGEEXEC
41     # e: disable EMUTRMAP E: enable EMUTRMAP
42     # m: disable MPROTECT M: enable MPROTECT
43     # r: disable RANDMMAP R: enable RANDMMAP
44     # s: disable SEGMEXEC S: enable SEGMEXEC
45     #
46 blueness 1.11 # Default flags are 'PeMRS', which are the most restrictive settings. Refer
47     # to http://pax.grsecurity.net/ for details on what these flags are all about.
48     # Do not use the obsolete flag 'x'/'X' which has been deprecated.
49     #
50     # Please confirm any relaxation of restrictions with the Gentoo Hardened team.
51     # Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on
52     # the bug report.
53 kevquinn 1.1 pax-mark() {
54 kevquinn 1.6 local f flags fail=0 failures="" zero_load_alignment
55 kevquinn 1.4 # Ignore '-' characters - in particular so that it doesn't matter if
56     # the caller prefixes with -
57 kevquinn 1.3 flags=${1//-}
58 kevquinn 1.2 shift
59 blueness 1.11 # Try paxctl, then scanelf. paxctl is preferred.
60 kevquinn 1.4 if type -p paxctl > /dev/null && hasq PT ${PAX_MARKINGS}; then
61     # Try paxctl, the upstream supported tool.
62 kevquinn 1.7 elog "PT PaX marking -${flags}"
63 kevquinn 1.5 _pax_list_files elog "$@"
64 kevquinn 1.4 for f in "$@"; do
65 kevquinn 1.6 # First, try modifying the existing PAX_FLAGS header
66 kevquinn 1.5 paxctl -q${flags} "${f}" && continue
67 kevquinn 1.6 # Second, try stealing the (unused under PaX) PT_GNU_STACK header
68 kevquinn 1.5 paxctl -qc${flags} "${f}" && continue
69 kevquinn 1.6 # Third, try pulling the base down a page, to create space and
70     # insert a PT_GNU_STACK header (works on ET_EXEC)
71 kevquinn 1.5 paxctl -qC${flags} "${f}" && continue
72 kevquinn 1.6 # Fourth - check if it loads to 0 (probably an ET_DYN) and if so,
73     # try rebasing with prelink first to give paxctl some space to
74     # grow downwards into.
75     if type -p objdump > /dev/null && type -p prelink > /dev/null; then
76     zero_load_alignment=$(objdump -p "${f}" | \
77     grep -E '^[[:space:]]*LOAD[[:space:]]*off[[:space:]]*0x0+[[:space:]]' | \
78     sed -e 's/.*align\(.*\)/\1/')
79     if [[ ${zero_load_alignment} != "" ]]; then
80     prelink -r $(( 2*(${zero_load_alignment}) )) &&
81     paxctl -qC${flags} "${f}" && continue
82     fi
83     fi
84 kevquinn 1.3 fail=1
85     failures="${failures} ${f}"
86     done
87 kevquinn 1.5 elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
88 kevquinn 1.6 # Try scanelf, the Gentoo swiss-army knife ELF utility
89 blueness 1.11 # Currently this sets PT if it can, no option to control what it does.
90 kevquinn 1.7 elog "Fallback PaX marking -${flags}"
91 kevquinn 1.5 _pax_list_files elog "$@"
92     scanelf -Xxz ${flags} "$@"
93     elif [[ ${PAX_MARKINGS} != "none" ]]; then
94 kevquinn 1.4 # Out of options!
95 kevquinn 1.3 failures="$*"
96 kevquinn 1.2 fail=1
97 kevquinn 1.1 fi
98 kevquinn 1.3 if [[ ${fail} == 1 ]]; then
99     ewarn "Failed to set PaX markings -${flags} for:"
100     _pax_list_files ewarn ${failures}
101     ewarn "Executables may be killed by PaX kernels."
102     fi
103 kevquinn 1.2 return ${fail}
104     }
105    
106 blueness 1.11 # @FUNCTION: list-paxables
107     # @USAGE: {<files>}
108     # @RETURN: Subset of {<files>} which are ELF executables or shared objects
109     # @DESCRIPTION:
110     # Print to stdout all of the <files> that are suitable to have PaX flag
111     # markings, i.e., filter out the ELF executables or shared objects from a list
112     # of files. This is useful for passing wild-card lists to pax-mark, although
113     # in general it is preferable for ebuilds to list precisely which ELFS are to
114     # be marked. Often not all the ELF installed by a package need remarking.
115     # @EXAMPLE:
116     # pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
117 kevquinn 1.4 list-paxables() {
118 kevquinn 1.6 file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//'
119 kevquinn 1.4 }
120    
121 blueness 1.11 # @FUNCTION: host-is-pax
122     # @RETURN: Shell true if the build process is PaX enabled, shell false otherwise
123     # @DESCRIPTION:
124     # This is intended for use where the build process must be modified conditionally
125     # depending on whether the host is PaX enabled or not. It is not intedened to
126     # determine whether the final binaries need PaX markings. Note: if procfs is
127     # not mounted on /proc, this returns shell false (e.g. Gentoo/FBSD).
128 kevquinn 1.2 host-is-pax() {
129 kevquinn 1.4 grep -qs ^PaX: /proc/self/status
130     }
131    
132    
133     # INTERNAL FUNCTIONS
134     # ------------------
135     #
136     # These functions are for use internally by the eclass - do not use
137     # them elsewhere as they are not supported (i.e. they may be removed
138     # or their function may change arbitratily).
139    
140     # Display a list of things, one per line, indented a bit, using the
141     # display command in $1.
142     _pax_list_files() {
143     local f cmd
144     cmd=$1
145     shift
146     for f in "$@"; do
147     ${cmd} " ${f}"
148     done
149 kevquinn 1.1 }

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