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Revision 1.10 - (hide annotations) (download)
Tue Mar 9 10:35:33 2010 UTC (4 years, 7 months ago) by nyhm
Branch: MAIN
Changes since 1.9: +2 -2 lines
fix comment

1 kevquinn 1.1 # Copyright 1999-2006 Gentoo Foundation
2     # Distributed under the terms of the GNU General Public License v2
3 nyhm 1.10 # $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.9 2008/07/07 16:54:56 betelgeuse Exp $
4 kevquinn 1.1
5     # Author:
6     # Kevin F. Quinn <kevquinn@gentoo.org>
7     #
8     # This eclass provides support for manipulating PaX markings on ELF
9 kevquinn 1.4 # binaries, wrapping the use of the chpaxi, paxctl and scanelf utilities.
10     # Currently it decides which to use depending on what is installed on the
11     # build host; this may change in the future to use a control variable
12     # (which would also mean modifying DEPEND to bring in sys-apps/paxctl etc).
13     #
14     #
15     # CONTROL
16     # -------
17     #
18     # To control what markings are set, assign PAX_MARKINGS in
19     # /etc/make.conf to contain the strings "EI" and/or "PT".
20     # If EI is present in PAX_MARKINGS (and the chpax utility
21     # is present), the legacy 'chpax' style markings will be
22     # set. If PT is present in PAX_MARKINGS (and the paxctl
23     # utility is present), the 'paxctl' markings will be set.
24 nyhm 1.10 # Default is to try to do both. Set it to "none" to prevent
25 kevquinn 1.4 # any markings being made.
26     #
27     #
28     # PROVIDED FUNCTIONS
29     # ------------------
30     #
31     #### pax-mark <flags> {<ELF files>}
32     # Marks files <files> with provided PaX flags <flags>
33     #
34     # Please confirm any relaxation of restrictions with the
35     # Gentoo Hardened team; either ask on the gentoo-hardened
36     # mailing list, or CC/assign hardened@g.o on a bug.
37     #
38     # Flags are passed directly to the utilities unchanged. Possible
39     # flags at the time of writing, taken from /sbin/paxctl, are:
40     #
41     # p: disable PAGEEXEC P: enable PAGEEXEC
42     # e: disable EMUTRMAP E: enable EMUTRMAP
43     # m: disable MPROTECT M: enable MPROTECT
44     # r: disable RANDMMAP R: enable RANDMMAP
45     # s: disable SEGMEXEC S: enable SEGMEXEC
46     #
47     # Default flags are 'PeMRS', which are the most restrictive
48     # settings. Refer to http://pax.grsecurity.net/ for details
49     # on what these flags are all about. There is an obsolete
50     # flag 'x'/'X' which has been removed from PaX.
51     #
52     # If chpax is not installed, the legacy EI flags (which are
53     # not strip-safe, and strictly speaking violate the ELF spec)
54     # will not be set. If paxctl is not installed, it falls back
55     # to scanelf. scanelf is always present, but currently doesn't
56     # quite do all that paxctl can do.
57     # Returns fail if one or more files could not be marked.
58     #
59     #
60     #### list-paxables {<files>}
61     # Prints to stdout all of <files> that are suitable to having PaX
62     # flags (i.e. filter to just ELF files). Useful for passing wild-card
63     # lists of files to pax-mark, although in general it is preferable
64     # for ebuilds to list precisely which executables are to be marked.
65     # Use like:
66     # pax-mark -m $(list-paxables ${S}/{,usr/}bin/*)
67     #
68     #
69     #### host-is-pax
70     # Returns true if the host has a PaX-enabled kernel, false otherwise.
71     # Intended for use where the build process must be modified conditionally
72     # in order to satisfy PaX. Note; it is _not_ intended to indicate
73     # whether the final executables should satisfy PaX - executables should
74     # always be marked appropriately even if they're only going to be
75     # installed on a non-PaX system.
76 kevquinn 1.1
77     inherit eutils
78    
79 kevquinn 1.4 # Default to both EI and PT markings.
80     PAX_MARKINGS=${PAX_MARKINGS:="EI PT"}
81 kevquinn 1.1
82 kevquinn 1.4 # pax-mark <flags> {<ELF files>}
83 kevquinn 1.1 pax-mark() {
84 kevquinn 1.6 local f flags fail=0 failures="" zero_load_alignment
85 kevquinn 1.4 # Ignore '-' characters - in particular so that it doesn't matter if
86     # the caller prefixes with -
87 kevquinn 1.3 flags=${1//-}
88 kevquinn 1.2 shift
89 kevquinn 1.4 # Try chpax, for (deprecated) EI legacy marking.
90     if type -p chpax > /dev/null && hasq EI ${PAX_MARKINGS}; then
91 kevquinn 1.7 elog "Legacy EI PaX marking -${flags}"
92 kevquinn 1.5 _pax_list_files elog "$@"
93 kevquinn 1.4 for f in "$@"; do
94 kevquinn 1.5 chpax -${flags} "${f}" && continue
95 kevquinn 1.3 fail=1
96     failures="${failures} ${f}"
97     done
98 kevquinn 1.1 fi
99 kevquinn 1.4 # Try paxctl, then scanelf - paxctl takes precedence
100     # over scanelf.
101     if type -p paxctl > /dev/null && hasq PT ${PAX_MARKINGS}; then
102     # Try paxctl, the upstream supported tool.
103 kevquinn 1.7 elog "PT PaX marking -${flags}"
104 kevquinn 1.5 _pax_list_files elog "$@"
105 kevquinn 1.4 for f in "$@"; do
106 kevquinn 1.6 # First, try modifying the existing PAX_FLAGS header
107 kevquinn 1.5 paxctl -q${flags} "${f}" && continue
108 kevquinn 1.6 # Second, try stealing the (unused under PaX) PT_GNU_STACK header
109 kevquinn 1.5 paxctl -qc${flags} "${f}" && continue
110 kevquinn 1.6 # Third, try pulling the base down a page, to create space and
111     # insert a PT_GNU_STACK header (works on ET_EXEC)
112 kevquinn 1.5 paxctl -qC${flags} "${f}" && continue
113 kevquinn 1.6 # Fourth - check if it loads to 0 (probably an ET_DYN) and if so,
114     # try rebasing with prelink first to give paxctl some space to
115     # grow downwards into.
116     if type -p objdump > /dev/null && type -p prelink > /dev/null; then
117     zero_load_alignment=$(objdump -p "${f}" | \
118     grep -E '^[[:space:]]*LOAD[[:space:]]*off[[:space:]]*0x0+[[:space:]]' | \
119     sed -e 's/.*align\(.*\)/\1/')
120     if [[ ${zero_load_alignment} != "" ]]; then
121     prelink -r $(( 2*(${zero_load_alignment}) )) &&
122     paxctl -qC${flags} "${f}" && continue
123     fi
124     fi
125 kevquinn 1.3 fail=1
126     failures="${failures} ${f}"
127     done
128 kevquinn 1.5 elif type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
129 kevquinn 1.6 # Try scanelf, the Gentoo swiss-army knife ELF utility
130 kevquinn 1.4 # Currently this sets EI and PT if it can, no option to
131     # control what it does.
132 kevquinn 1.7 elog "Fallback PaX marking -${flags}"
133 kevquinn 1.5 _pax_list_files elog "$@"
134     scanelf -Xxz ${flags} "$@"
135     elif [[ ${PAX_MARKINGS} != "none" ]]; then
136 kevquinn 1.4 # Out of options!
137 kevquinn 1.3 failures="$*"
138 kevquinn 1.2 fail=1
139 kevquinn 1.1 fi
140 kevquinn 1.3 if [[ ${fail} == 1 ]]; then
141     ewarn "Failed to set PaX markings -${flags} for:"
142     _pax_list_files ewarn ${failures}
143     ewarn "Executables may be killed by PaX kernels."
144     fi
145 kevquinn 1.2 return ${fail}
146     }
147    
148 kevquinn 1.4 # list-paxables {<files>}
149     list-paxables() {
150 kevquinn 1.6 file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//'
151 kevquinn 1.4 }
152    
153     # host-is-pax
154     # Note: if procfs is not on /proc, this returns False (e.g. Gentoo/FBSD).
155 kevquinn 1.2 host-is-pax() {
156 kevquinn 1.4 grep -qs ^PaX: /proc/self/status
157     }
158    
159    
160     # INTERNAL FUNCTIONS
161     # ------------------
162     #
163     # These functions are for use internally by the eclass - do not use
164     # them elsewhere as they are not supported (i.e. they may be removed
165     # or their function may change arbitratily).
166    
167     # Display a list of things, one per line, indented a bit, using the
168     # display command in $1.
169     _pax_list_files() {
170     local f cmd
171     cmd=$1
172     shift
173     for f in "$@"; do
174     ${cmd} " ${f}"
175     done
176 kevquinn 1.1 }

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