vidoas.sh

   1 #!/bin/sh
   2
   3 # Copyright (c) 2020 Kimmo Suominen <kim@netbsd.org>
   4 #
   5 # Permission to use, copy, modify, and distribute this software for any
   6 # purpose with or without fee is hereby granted, provided that the above
   7 # copyright notice and this permission notice appear in all copies.
   8 #
   9 # THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
  10 # WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
  11 # WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
  12 # AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  13 # DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
  14 # OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  15 # TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  16 # PERFORMANCE OF THIS SOFTWARE.
  17
  18 # Edit a temporary copy of the doas.conf file and check it for syntax
  19 # errors before installing it as the actual doas.conf file.
  20
  21 set -eu
  22
  23 PATH=/bin:/usr/bin:/usr/local/bin
  24 export PATH
  25
  26 PROG="${0##*/}"
  27
  28 umask 022
  29
  30 DOAS_CONF=@DOAS_CONF@
  31 doas_conf_mode="0600"
  32
  33 die()
  34 {
  35     echo "${PROG}: ${@}" 1>&2
  36     exit 1
  37 }
  38
  39 warn()
  40 {
  41     echo "${PROG}: ${@}" 1>&2
  42 }
  43
  44 get_intr()
  45 {
  46     stty -a \
  47     | sed -En '
  48         /^(.* )?intr = / {
  49             s///
  50             s/;.*$//
  51             p
  52         }
  53     '
  54 }
  55
  56 owner_of()
  57 {
  58     local file
  59     file="${1}"
  60
  61     if stat --version >/dev/null 2>&1
  62     then
  63         stat -c '%U' "${file}"
  64     else
  65         stat -f '%Su' "${file}"
  66     fi \
  67     | awk '{print $1; exit}'
  68 }
  69
  70 set_trap_rm()
  71 {
  72     local file file_list
  73     file_list=
  74     for file
  75     do
  76         file_list="${file_list} '${file}'"
  77     done
  78     if [ -n "${file_list}" ]
  79     then
  80         trap "rm -f ${file_list}" 0 1 2 15
  81     fi
  82 }
  83
  84 usage()
  85 {
  86     cat <<EOF
  87 Usage:  ${PROG} [-n] [file]
  88         ${PROG} -h
  89
  90 Edit a temporary copy of a doas configuration file and check it for
  91 syntax errors before installing it as the actual configuration file.
  92
  93 When no file is named, ${PROG} will edit the default configuration file
  94 for doas(1): @DOAS_CONF@
  95
  96 Options:
  97 -h      Show this usage.
  98 -n      Do not edit the file, just perform prerequisite checks. If this
  99         switch is repeated, all output will be suppressed and the check
 100         result is only indicated by the exit status.
 101 EOF
 102 }
 103
 104 noop=0
 105
 106 while getopts hn opt
 107 do
 108     case "${opt}" in
 109     h) usage; exit 0;;
 110     n) noop=$((${noop} + 1));;
 111     *) usage 1>&2; exit 1;;
 112     esac
 113 done
 114 shift $((${OPTIND} - 1))
 115
 116 case ${#} in
 117 0) ;;
 118 1) DOAS_CONF="${1}";;
 119 *) usage 1>&2; exit 1;;
 120 esac
 121
 122 case ${noop} in
 123 0) noop=false;;
 124 1) noop=true;;
 125 *) noop=true; exec >/dev/null 2>&1;;
 126 esac
 127
 128 case "${DOAS_CONF}" in
 129 -*)
 130     warn "Invalid filename: ${DOAS_CONF}"
 131     die  "Try using './${DOAS_CONF}' instead"
 132     ;;
 133 esac
 134
 135 doas_conf_dir="$(dirname "${DOAS_CONF}")"
 136 doas_conf_base="$(basename "${DOAS_CONF}")"
 137 DOAS_CONF="${doas_conf_dir}/${doas_conf_base}"
 138 doas_lock_file="${DOAS_CONF}.lck"
 139
 140 # These checks are only for producing nicer diagnostic messages to the
 141 # user.  They are not relied on by the rest of the code.
 142
 143 if [ ! -e "${doas_conf_dir}" ]
 144 then
 145     die "${doas_conf_dir} does not exist"
 146 fi
 147
 148 if [ ! -d "${doas_conf_dir}" ]
 149 then
 150     die "${doas_conf_dir} is not a directory"
 151 fi
 152
 153 if [ ! -w "${doas_conf_dir}" ]
 154 then
 155     owner="$(owner_of "${doas_conf_dir}")"
 156     warn "${doas_conf_dir} is not writable"
 157     die "You probably need to run ${PROG} as ${owner:-root}"
 158 fi
 159
 160 tmp_doas="$(mktemp "${DOAS_CONF}.XXXXXXXXXX")" \
 161 || die "You probably need to run ${PROG} as root"
 162 set_trap_rm "${tmp_doas}"
 163
 164 # It is important that the ln(1) command fails if the target already
 165 # exists.  Some versions are known to behave like "ln -f" by default
 166 # (removing any existing target).  Adjust PATH to avoid such ln(1)
 167 # implementations.
 168
 169 tmp_test_ln="$(mktemp "${DOAS_CONF}.XXXXXXXXXX")"
 170 set_trap_rm "${tmp_doas}" "${tmp_test_ln}"
 171
 172 if ln "${tmp_doas}" "${tmp_test_ln}" 2>/dev/null
 173 then
 174     die 'ln(1) is not safe for creating lock files, bailing'
 175 fi
 176
 177 # If a doas.conf file exists, copy it into the temporary file for
 178 # editing.  If none exist, the editor will open with an empty file.
 179
 180 if [ -f "${DOAS_CONF}" ]
 181 then
 182     if [ -r "${DOAS_CONF}" ]
 183     then
 184         cp "${DOAS_CONF}" "${tmp_doas}"
 185     else
 186         die "${DOAS_CONF} is not readable"
 187     fi
 188 fi
 189
 190 if ${noop}
 191 then
 192     if ! doas -C "${DOAS_CONF}"
 193     then
 194         die "${DOAS_CONF} contains syntax errors."
 195     fi
 196     warn 'OK: Prerequisite checks passed'
 197     exit 0
 198 fi
 199
 200 # Link the temporary file to the lock file.
 201
 202 if ln "${tmp_doas}" "${doas_lock_file}"
 203 then
 204     set_trap_rm "${tmp_doas}" "${tmp_test_ln}" "${doas_lock_file}"
 205 else
 206     die "${DOAS_CONF} is already locked"
 207 fi
 208
 209 # Some versions of vi(1) exit with a code that reflects the number of
 210 # editing errors made.  This is why we ignore the exit code from the
 211 # editor.
 212
 213 "${EDITOR:-vi}" "${tmp_doas}" || true
 214
 215 while ! doas -C "${tmp_doas}"
 216 do
 217     warn "Press enter to edit doas.conf again to fix it,"
 218     warn "or interrupt ($(get_intr)) to cancel."
 219     read status
 220     "${EDITOR:-vi}" "${tmp_doas}" || true
 221 done
 222
 223 # Use mv(1) to rename the temporary file to doas.conf as it is atomic.
 224 # Update: No longer use mv as it messes up permissions on the doas.conf file.
 225 # Use install with ownership set to root.
 226
 227 if [ -s "${tmp_doas}" ]
 228 then
 229     if cmp -s "${tmp_doas}" "${DOAS_CONF}"
 230     then
 231         warn "No changes made"
 232         warn "${DOAS_CONF} unchanged"
 233     else
 234         install -o root -m "${doas_conf_mode}" \
 235             "${tmp_doas}" "${DOAS_CONF}" \
 236         && warn "${DOAS_CONF} updated"
 237     fi
 238 else
 239     warn "Not installing an empty doas.conf file"
 240     warn "${DOAS_CONF} unchanged"
 241 fi