1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
|
# 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 ${PAX_MARKINGS}; then
_pax_list_files einfo "$@"
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} "${f}" && continue
# Second, try creating a PT_PAX header (works on ET_EXEC).
# Even though this is less safe, most exes need it. #463170
paxctl -qC${flags} "${f}" && continue
# Third, try stealing the (unused under PaX) PT_GNU_STACK header
paxctl -qc${flags} "${f}" && continue
fi
# Next try paxctl-ng -> this will not create/convert any program headers.
if type -p paxctl-ng > /dev/null && paxctl-ng -L ; then
einfo "PT PaX marking -${flags} ${f} with paxctl-ng"
flags="${flags//z}"
[[ ${dodefault} == "yes" ]] && paxctl-ng -L -z "${f}"
[[ "${flags}" ]] || continue
paxctl-ng -L -${flags} "${f}" && continue
fi
# Finally fall back on scanelf.
if type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then
scanelf -Xxz ${flags} "$f"
# 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 ${PAX_MARKINGS}; then
_pax_list_files einfo "$@"
flags="${flags//z}"
for f in "$@"; do
# First try paxctl-ng.
if type -p paxctl-ng > /dev/null && paxctl-ng -l ; then
einfo "XT PaX marking -${flags} ${f} with paxctl-ng"
[[ ${dodefault} == "yes" ]] && paxctl-ng -d "${f}"
[[ "${flags}" ]] || continue
paxctl-ng -l -${flags} "${f}" && continue
fi
# Next try setfattr.
if type -p setfattr > /dev/null; then
[[ "${flags//[!Ee]}" ]] || flags+="e" # bug 447150
einfo "XT PaX marking -${flags} ${f} with setfattr"
[[ ${dodefault} == "yes" ]] && setfattr -x "user.pax.flags" "${f}"
setfattr -n "user.pax.flags" -v "${flags}" "${f}" && 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
|
GitWeb