fcaps.eclass (6037B)
1 # Copyright 1999-2015 Gentoo Foundation
2 # Distributed under the terms of the GNU General Public License v2
3 # $Id$
4
5 # @ECLASS: fcaps.eclass
6 # @MAINTAINER:
7 # Constanze Hausner <constanze@gentoo.org>
8 # base-system@gentoo.org
9 # @BLURB: function to set POSIX file-based capabilities
10 # @DESCRIPTION:
11 # This eclass provides a function to set file-based capabilities on binaries.
12 # This is not the same as USE=caps which controls runtime capability changes,
13 # often via packages like libcap.
14 #
15 # Due to probable capability-loss on moving or copying, this happens in
16 # pkg_postinst-phase (at least for now).
17 #
18 # @EXAMPLE:
19 # You can manually set the caps on ping and ping6 by doing:
20 # @CODE
21 # pkg_postinst() {
22 # fcaps cap_net_raw bin/ping bin/ping6
23 # }
24 # @CODE
25 #
26 # Or set it via the global ebuild var FILECAPS:
27 # @CODE
28 # FILECAPS=(
29 # cap_net_raw bin/ping bin/ping6
30 # )
31 # @CODE
32
33 if [[ -z ${_FCAPS_ECLASS} ]]; then
34 _FCAPS_ECLASS=1
35
36 IUSE="+filecaps"
37
38 # We can't use libcap-ng atm due to #471414.
39 DEPEND="filecaps? ( sys-libs/libcap )"
40
41 # @ECLASS-VARIABLE: FILECAPS
42 # @DEFAULT_UNSET
43 # @DESCRIPTION:
44 # An array of fcap arguments to use to automatically execute fcaps. See that
45 # function for more details.
46 #
47 # All args are consumed until the '--' marker is found. So if you have:
48 # @CODE
49 # FILECAPS=( moo cow -- fat cat -- chubby penguin )
50 # @CODE
51 #
52 # This will end up executing:
53 # @CODE
54 # fcaps moo cow
55 # fcaps fat cat
56 # fcaps chubby penguin
57 # @CODE
58 #
59 # Note: If you override pkg_postinst, you must call fcaps_pkg_postinst yourself.
60
61 # @FUNCTION: fcaps
62 # @USAGE: [-o <owner>] [-g <group>] [-m <mode>] [-M <caps mode>] <capabilities> <file[s]>
63 # @DESCRIPTION:
64 # Sets the specified capabilities on the specified files.
65 #
66 # The caps option takes the form as expected by the cap_from_text(3) man page.
67 # If no action is specified, then "=ep" will be used as a default.
68 #
69 # If the file is a relative path (e.g. bin/foo rather than /bin/foo), then the
70 # appropriate path var ($D/$ROOT/etc...) will be prefixed based on the current
71 # ebuild phase.
72 #
73 # The caps mode (default 711) is used to set the permission on the file if
74 # capabilities were properly set on the file.
75 #
76 # If the system is unable to set capabilities, it will use the specified user,
77 # group, and mode (presumably to make the binary set*id). The defaults there
78 # are 0:0 and 4711. Otherwise, the ownership and permissions will be
79 # unchanged.
80 fcaps() {
81 debug-print-function ${FUNCNAME} "$@"
82
83 # Process the user options first.
84 local owner='0'
85 local group='0'
86 local mode='4711'
87 local caps_mode='711'
88
89 while [[ $# -gt 0 ]] ; do
90 case $1 in
91 -o) owner=$2; shift;;
92 -g) group=$2; shift;;
93 -m) mode=$2; shift;;
94 -M) caps_mode=$2; shift;;
95 *) break;;
96 esac
97 shift
98 done
99
100 [[ $# -lt 2 ]] && die "${FUNCNAME}: wrong arg count"
101
102 local caps=$1
103 [[ ${caps} == *[-=+]* ]] || caps+="=ep"
104 shift
105
106 local root
107 case ${EBUILD_PHASE} in
108 compile|install|preinst)
109 root=${ED:-${D}}
110 ;;
111 postinst)
112 root=${EROOT:-${ROOT}}
113 ;;
114 esac
115
116 # Process every file!
117 local file
118 for file ; do
119 [[ ${file} != /* ]] && file="${root}${file}"
120
121 if use filecaps ; then
122 # Try to set capabilities. Ignore errors when the
123 # fs doesn't support it, but abort on all others.
124 debug-print "${FUNCNAME}: setting caps '${caps}' on '${file}'"
125
126 # If everything goes well, we don't want the file to be readable
127 # by people.
128 chmod ${caps_mode} "${file}" || die
129
130 # Set/verify funcs for sys-libs/libcap.
131 _libcap() { setcap "${caps}" "${file}" ; }
132 _libcap_verify() { setcap -v "${caps}" "${file}" >/dev/null ; }
133
134 # Set/verify funcs for sys-libs/libcap-ng.
135 # Note: filecap only supports =ep mode.
136 # It also expects a different form:
137 # setcap cap_foo,cap_bar
138 # filecap foo bar
139 _libcap_ng() {
140 local caps=",${caps%=ep}"
141 filecap "${file}" "${caps//,cap_}"
142 }
143 _libcap_ng_verify() {
144 # libcap-ng has a crappy interface
145 local rcaps icaps caps=",${caps%=ep}"
146 rcaps=$(filecap "${file}" | \
147 sed -nr \
148 -e "s:^.{${#file}} +::" \
149 -e 's:, +:\n:g' \
150 -e 2p | \
151 LC_ALL=C sort)
152 [[ ${PIPESTATUS[0]} -eq 0 ]] || return 1
153 icaps=$(echo "${caps//,cap_}" | LC_ALL=C sort)
154 [[ ${rcaps} == ${icaps} ]]
155 }
156
157 local out cmd notfound=0
158 for cmd in _libcap _libcap_ng ; do
159 if ! out=$(LC_ALL=C ${cmd} 2>&1) ; then
160 case ${out} in
161 *"command not found"*)
162 : $(( ++notfound ))
163 continue
164 ;;
165 # ENOTSUP and EOPNOTSUPP might be the same value which means
166 # strerror() on them is unstable -- we can get both. #559608
167 *"Not supported"*|\
168 *"Operation not supported"*)
169 local fstype=$(stat -f -c %T "${file}")
170 ewarn "Could not set caps on '${file}' due to missing filesystem support:"
171 ewarn "* enable XATTR support for '${fstype}' in your kernel (if configurable)"
172 ewarn "* mount the fs with the user_xattr option (if not the default)"
173 ewarn "* enable the relevant FS_SECURITY option (if configurable)"
174 break
175 ;;
176 *)
177 eerror "Setting caps '${caps}' on file '${file}' failed:"
178 eerror "${out}"
179 die "could not set caps"
180 ;;
181 esac
182 else
183 # Sanity check that everything took.
184 ${cmd}_verify || die "Checking caps '${caps}' on '${file}' failed"
185
186 # Everything worked. Move on to the next file.
187 continue 2
188 fi
189 done
190 if [[ ${notfound} -eq 2 ]] && [[ -z ${_FCAPS_WARNED} ]] ; then
191 _FCAPS_WARNED="true"
192 ewarn "Could not find cap utils; make sure libcap or libcap-ng is available."
193 fi
194 fi
195
196 # If we're still here, setcaps failed.
197 debug-print "${FUNCNAME}: setting owner/mode on '${file}'"
198 chown "${owner}:${group}" "${file}" || die
199 chmod ${mode} "${file}" || die
200 done
201 }
202
203 # @FUNCTION: fcaps_pkg_postinst
204 # @DESCRIPTION:
205 # Process the FILECAPS array.
206 fcaps_pkg_postinst() {
207 local arg args=()
208 for arg in "${FILECAPS[@]}" "--" ; do
209 if [[ ${arg} == "--" ]] ; then
210 fcaps "${args[@]}"
211 args=()
212 else
213 args+=( "${arg}" )
214 fi
215 done
216 }
217
218 EXPORT_FUNCTIONS pkg_postinst
219
220 fi