eclass/fcaps.eclass

   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 root: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='root'
  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