mdw@git.distorted.org.uk Git - distorted-keys/blob - keyfunc.sh.in

   1 ### -*-sh-*-
   2 ###
   3 ### Common key management functions.
   4 ###
   5 ### (c) 2011 Mark Wooding
   6 ###
   7
   8 ###----- Licensing notice ---------------------------------------------------
   9 ###
  10 ### This file is part of the distorted.org.uk key management suite.
  11 ###
  12 ### distorted-keys is free software; you can redistribute it and/or modify
  13 ### it under the terms of the GNU General Public License as published by
  14 ### the Free Software Foundation; either version 2 of the License, or
  15 ### (at your option) any later version.
  16 ###
  17 ### distorted-keys is distributed in the hope that it will be useful,
  18 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ### GNU General Public License for more details.
  21 ###
  22 ### You should have received a copy of the GNU General Public License
  23 ### along with distorted-keys; if not, write to the Free Software Foundation,
  24 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25
  26 quis=${0##*/}
  27
  28 ###--------------------------------------------------------------------------
  29 ### Configuration variables.
  30
  31 ## Automatically configured pathnames.
  32 PACKAGE="@PACKAGE@" VERSION="@VERSION@"
  33 bindir="@bindir@"
  34
  35 ## Read user configuration.
  36 if [ -f $ETC/keys.conf ]; then . $ETC/keys.conf; fi
  37
  38 ## Maybe turn on debugging.
  39 case "${KEYS_DEBUG+t}" in t) set -x ;; esac
  40
  41 ###--------------------------------------------------------------------------
  42 ### Cleanup handling.
  43
  44 cleanups=""
  45 cleanup () { cleanups=${cleanups+$cleanups }$1; }
  46 runcleanups () { for i in $cleanups; do $i; done; }
  47 trap 'rc=$?; runcleanups; exit $rc' EXIT
  48 trap 'trap "" EXIT; runcleanups; exit 127' INT TERM
  49
  50 ###--------------------------------------------------------------------------
  51 ### Utility functions.
  52
  53 reqsafe () {
  54   ## Fail unless a safe directory is set.
  55
  56   err="$quis: (CONFIGURATION ERROR)"
  57   case ${SAFE+t} in
  58     t) ;;
  59     *) echo >&2 "$err: no SAFE directory"; exit 1 ;;
  60   esac
  61   if [ ! -d "$SAFE" ]; then
  62     echo >&2 "$err: SAFE path \`$SAFE' isn't a directory"
  63     exit 1
  64   fi
  65   case "$SAFE" in
  66     [!/]* | *[][[:space:]*?]*)
  67       echo >&2 "$err: SAFE path \`$SAFE' contains bad characters"
  68       exit 1
  69       ;;
  70   esac
  71   ls -ld "$SAFE" | {
  72     me=$(id -un)
  73     read perm _ user stuff
  74     case "$perm:$user" in
  75       d???------:"$me") ;;
  76       *)
  77         echo >&2 "$err: SAFE path \`$SAFE' has bad owner or permissions"
  78         exit 1
  79         ;;
  80     esac
  81   }
  82 }
  83
  84 ## Temporary directory.
  85 unset tmp
  86 rmtmp () { case ${tmp+t} in t) cd /; rm -rf $tmp ;; esac; }
  87 cleanup rmtmp
  88 mktmp () {
  89   ## Make a temporary directory and store its name in `tmp'.
  90
  91   case "${tmp+t}" in t) return ;; esac
  92   reqsafe
  93   tmp="$SAFE/keys.tmp.$$"
  94   rm -rf "$tmp"
  95   mkdir -m700 "$tmp"
  96 }
  97
  98 reqtmp () {
  99   ## Fail unless a temporary directory is set.
 100
 101   case ${tmp+t} in
 102     t) ;;
 103     *) echo >&2 "$quis (INTERNAL): no tmp directory set"; exit 127 ;;
 104   esac
 105 }
 106
 107 parse_keylabel () {
 108   key=$1
 109   ## Parse the key label string KEY.  Set `kdir' to the base path to use for
 110   ## the key's storage, and `kowner' to the key owner's name.
 111
 112   case "$key" in
 113     *:*) kowner=${key%%:*} klabel=${key#*:} ;;
 114     *) kowner=$USERV_USER klabel=$key ;;
 115   esac
 116   checkword "key owner name" "$kowner"
 117   checklabel "key" "$klabel"
 118   kdir=$KEYS/store/$kowner/$klabel
 119   knub=$KEYS/nub/$kowner/$klabel
 120 }
 121
 122 ###--------------------------------------------------------------------------
 123 ### Input validation functions.
 124
 125 nl="
 126 "
 127 check () {
 128   ckwhat=$1 ckpat=$2 thing=$3
 129   ## Verify that THING matches the (anchored, basic) regular expression
 130   ## CKPAT.  Since matching newlines is hard to do portably, also check that
 131   ## THING doesn't contain any.  If the checks fail, report an error and
 132   ## exit.
 133
 134   validp=t
 135   case "$thing" in
 136     *"$nl"*) validp=nil ;;
 137     *) if ! expr >/dev/null "$thing" : "$ckpat\$"; then validp=nil; fi ;;
 138   esac
 139   case $validp in
 140     nil) echo >&2 "$quis: bad $ckwhat \`$thing'"; exit 1 ;;
 141   esac
 142 }
 143
 144 ## Regular expressions for validating input.
 145 R_IDENTCHARS="A-Za-z0-9_"
 146 R_WORDCHARS="-$R_IDENTCHARS!%@+="
 147 R_IDENT="[$R_IDENTCHARS][$R_IDENTCHARS]*"
 148 R_WORD="[$R_WORDCHARS][$R_WORDCHARS]*"
 149 R_WORDSEQ="[$R_WORDCHARS[:space:]][$R_WORDCHARS[:space:]]*"
 150 R_NUMERIC='\(\([1-9][0-9]*\)\{0,1\}0\{0,1\}\)'
 151 R_LABEL="\($R_WORD\(/$R_WORD\)*\)"
 152 R_LINE=".*"
 153
 154 ## Various validation functions.
 155 checknumber () { check "$1" "$R_NUMERIC" "$2"; }
 156 checkident () { check "$1" "$R_IDENT" "$2"; }
 157 checkword () { check "$1" "$R_WORD" "$2"; }
 158 checklabel () { check "$1 label" "$R_LABEL" "$2"; }
 159
 160 ###--------------------------------------------------------------------------
 161 ### Key storage and properties.
 162
 163 getsysprofile () {
 164   profile=$1
 165   ## Write the named system PROFILE to standard output.
 166
 167   $bindir/extract-profile "$profile" $ETC/profile.d/
 168 }
 169
 170 setprops () {
 171   what=$1 prefix=$2; shift 2
 172   ## Set variables based on the NAME=VALUE assignments in the arguments.  The
 173   ## value for property NAME is stored in the shell variable PREFIX_NAME.
 174
 175   for assg in "$@"; do
 176     goodp=t
 177     case "$assg" in
 178       *\=*) name=${assg%%=*} value=${assg#*=} ;;
 179       *) goodp=nil ;;
 180     esac
 181     case "$goodp,$name" in t,*[!0-9A-Za-z_]*=*) goodp=nil ;; esac
 182     case "$goodp" in
 183       nil) echo >&2 "$quis: bad $what assignment \`$assg'"; exit 1 ;;
 184     esac
 185     eval "$prefix$name=\$value"
 186   done
 187 }
 188
 189 checkprops () {
 190   whatprop=$1 prefix=$2; shift 2
 191   ## Check that property variables are set in accordance with the remaining
 192   ## TABLE arguments.  Each row of TABLE has the form
 193   ##
 194   ##    NAME OMIT PAT
 195   ##
 196   ## A table row is satisfied if there is a variable PREFIXNAME whose value
 197   ## matces the (basic) regular expression PAT, or if the variable is unset
 198   ## and OMIT is `t'.
 199
 200   for table in "$@"; do
 201     case "$table" in ?*) ;; *) continue ;; esac
 202     while read -r name omit pat; do
 203       eval foundp=\${$prefix$name+t}
 204       case "$foundp,$omit" in
 205         ,t) continue ;;
 206         ,nil)
 207           echo >&2 "$quis: missing $whatprop \`$name' required"
 208           exit 1
 209           ;;
 210       esac
 211       eval value=\$$prefix$name
 212       check "value for $whatprop \`$name'" "$pat" "$value"
 213     done <<EOF
 214 $table
 215 EOF
 216   done
 217 }
 218
 219 defprops () {
 220   name=$1
 221   ## Define a properties table NAME.
 222
 223   table=$(cat)
 224   eval $name=\$table
 225 }
 226
 227 defprops g_props <<EOF
 228 type                    nil     $R_IDENT
 229 recovery                t       $R_WORDSEQ
 230 random                  t       $R_WORD
 231 nub_hash                t       $R_WORD
 232 nubid_hash              t       $R_WORD
 233 nub_random_bytes        t       $R_NUMERIC
 234 EOF
 235
 236 readprops () {
 237   file=$1
 238   ## Read a profile from a file.  This doesn't check the form of the
 239   ## filename, so it's not suitable for unchecked input.  Properties are set
 240   ## using `setprops' with prefix `kprop_'.
 241
 242   ## Parse the settings from the file.
 243   exec 3<"$file"
 244   while read line; do
 245     case "$line" in "" | \#*) continue ;; esac
 246     setprops "property" kprop_ "$line"
 247   done <&3
 248   exec 3>&-
 249   checkprops "property" kprop_ "$g_props"
 250
 251   ## Fetch the key-type handling library.
 252   if [ ! -f $KEYSLIB/ktype.$kprop_type ]; then
 253     echo >&2 "$quis: unknown key type \`$kprop_type'"
 254     exit 1
 255   fi
 256   . $KEYSLIB/ktype.$kprop_type
 257   checkprops "property" kprop_ "$k_props"
 258 }
 259
 260 readmeta () {
 261   kdir=$1
 262   ## Read key metadata from KDIR.
 263
 264   { read profile; } <"$kdir"/meta
 265 }
 266
 267 makenub () {
 268   ## Generate a key nub in the default way, and write it to standard output.
 269   ## The properties `random', `nub_random_bytes' and `nub_hash' are referred
 270   ## to.
 271
 272   dd 2>/dev/null \
 273     if=/dev/${kprop_random-random} bs=1 count=${kprop_nub_random_bytes-64} |
 274   openssl dgst -${kprop_nub_hash-sha256} -binary |
 275   openssl base64
 276 }
 277
 278 nubid () {
 279   ## Compute a hash of the key nub in stdin, and write it to stdout in hex.
 280   ## The property `nubid_hash' is used.
 281
 282   { echo "distorted-keys nubid"; cat -; } |
 283   openssl dgst -${kprop_nubid_hash-sha256}
 284 }
 285
 286 subst () {
 287   what=$1 templ=$2 prefix=$3 pat=$4
 288   ## Substitute option values into the template TEMPL.  Each occurrence of
 289   ## %{VAR} is replaced by the value of the variable PREFIXVAR.  Finally, an
 290   ## error is reported unless the final value matches the regular expression
 291   ## PAT.
 292
 293   out=""
 294   rest=$templ
 295   while :; do
 296
 297     ## If there are no more markers to substitute, then finish.
 298     case "$rest" in *"%{"*"}"*) ;; *) out=$out$rest; break ;; esac
 299
 300     ## Split the template into three parts.
 301     left=${rest%%\%\{*} right=${rest#*\%\{}
 302     var=${right%%\}*} rest=${right#*\}}
 303     case "$var" in
 304       *-*) default=${var#*-} var=${var%%-*} defaultp=t ;;
 305       *) defaultp=nil ;;
 306     esac
 307
 308     ## Find the variable value.
 309     checkident "template variable name" "$var"
 310     eval foundp=\${$prefix$var+t}
 311     case $foundp,$defaultp in
 312       t,*) eval value=\$$prefix$var ;;
 313       ,t) value=$default ;;
 314       *)
 315         echo >&2 "$quis: option \`$var' unset, used in template \`$templ'"
 316         exit 1
 317         ;;
 318     esac
 319
 320     ## Do the substitution.
 321     out=$out$left$value
 322   done
 323
 324   ## Check the final result.
 325   check "$what" "$pat" "$out"
 326
 327   ## Done.
 328   echo "$out"
 329 }
 330
 331 read_profile () {
 332   profile=$1
 333   ## Read property settings from a profile.  The PROFILE name has the form
 334   ## [USER:]LABEL.  Properties are set using `setprops' with prefix `kprop_'.
 335
 336   reqtmp
 337   case "$profile" in
 338     :*)
 339       label=${profile#:} uservp=nil
 340       ;;
 341     *)
 342       user=$USERV_USER label=$profile uservp=t
 343       ;;
 344     *:*)
 345       user=${profile%%:*} label=${profile#*:} uservp=t
 346       ;;
 347   esac
 348   checkword "profile label" "$label"
 349
 350   ## Fetch the profile settings from the user.
 351   reqtmp
 352   case $uservp in
 353     t)
 354       checkword "profile user" "$user"
 355       userv "$user" cryptop-profile "$label" >$tmp/profile
 356       ;;
 357     nil)
 358       $bindir/extract-profile "$label" $ETC/profile.d/ >$tmp/profile
 359       ;;
 360   esac
 361
 362   ## Read the file.
 363   readprops $tmp/profile
 364 }
 365
 366 ###--------------------------------------------------------------------------
 367 ### General crypto operations.
 368
 369 c_genkey () {
 370   profile=$1 kdir=$2 knub=$3 hook=$4; shift 4
 371   ## Generate a key, and associate it with the named PROFILE (which is
 372   ## assumed already to have been read!); store the main data in KDIR, and
 373   ## the nub separately in the file KNUB; run HOOK after generation, passing
 374   ## it the working key directory and nub file.  Remaining arguments are
 375   ## options to the key type.
 376
 377   ## Set options and check them.
 378   setprops "option" kopt_ "$@"
 379   checkprops "option" kopt_ "$k_genopts"
 380
 381   ## Create directory structure and start writing metadata.
 382   rm -rf "$kdir.new"
 383   mkdir -m755 -p "$kdir.new"
 384   case "$knub" in */*) mkdir -m700 -p "${knub%/*}" ;; esac
 385   cat >"$kdir.new/meta" <<EOF
 386 $profile
 387 EOF
 388
 389   ## Generate the key.
 390   umask=$(umask); umask 077; >"$knub.new"; umask $umask
 391   k_generate "$kdir.new" "$knub.new"
 392   $hook "$kdir.new" "$knub.new"
 393
 394   ## Hash the nub.
 395   nubid <"$knub.new" >"$kdir.new/nubid"
 396
 397   ## Juggle everything into place.  Doing this atomically is very difficult,
 398   ## and requires more machinery than I can really justify here.  If
 399   ## something goes wrong halfway, it should always be possible to fix it,
 400   ## either by backing out (if $kdir.new still exists) or pressing on
 401   ## forwards (if not).
 402   rm -rf "$kdir.old"
 403   if [ -e "$kdir" ]; then mv "$kdir" "$kdir.old"; fi
 404   mv "$kdir.new" "$kdir"
 405   mv "$knub.new" "$knub"
 406   rm -rf "$kdir.old"
 407 }
 408
 409 c_encrypt () { k_encrypt "$@"; }
 410 c_decrypt () {
 411   if k_decrypt "$@" >$tmp/plain; then cat $tmp/plain
 412   else return $?
 413   fi
 414 }
 415 c_sign () { k_sign "$@"; }
 416 c_verify () { k_verify "$@"; }
 417
 418 ## Stub implementations.
 419 notsupp () { op=$1; echo >&2 "$quis: operation \`$op' not supported"; }
 420 k_info () { :; }
 421 k_encrypt () { notsupp encrypt; }
 422 k_decrypt () { notsupp decrypt; }
 423 k_sign () { notsupp sign; }
 424 k_verify () { notsupp verify; }
 425
 426 prepare () {
 427   key=$1 op=$2
 428   ## Prepare for a crypto operation OP, using the KEY.  This validates the
 429   ## key label, reads the profile, and checks the access-control list.  If OP
 430   ## is `-' then allow the operation unconditionally.
 431
 432   ## Find the key properties.
 433   parse_keylabel "$key"
 434   if [ ! -d $kdir ]; then echo >&2 "$quis: unknown key \`$key'"; exit 1; fi
 435   readmeta $kdir
 436   read_profile "$profile"
 437
 438   ## Check whether we're allowed to do this thing.  This is annoyingly
 439   ## fiddly.
 440   case $op in -) return ;; esac
 441   eval acl=\${kprop_acl_$op-!owner}
 442   verdict=forbid
 443   while :; do
 444
 445     ## Remove leading whitespace.
 446     while :; do
 447       case "$acl" in
 448         [[:space:]]*) acl=${acl#?} ;;
 449         *) break ;;
 450       esac
 451     done
 452
 453     ## If there's nothing left, leave.
 454     case "$acl" in ?*) ;; *) break ;; esac
 455
 456     ## Split off the leading word.
 457     case "$acl" in
 458       *[[:space:]]*) word=${acl%%[[:space:]]*} acl=${acl#*[[:space:]]} ;;
 459       *) word=$acl acl="" ;;
 460     esac
 461
 462     ## See what sense it has if it matches.
 463     case "$word" in
 464       -*) sense=forbid rest=${word#-} ;;
 465       *) sense=allow rest=$word ;;
 466     esac
 467
 468     ## See whether the calling user matches.
 469     case "$rest" in
 470       !owner) pat=$kowner list=$USERV_USER ;;
 471       !*) echo >&2 "$quis: unknown ACL token \`$word'" ;;
 472       %*) pat=${rest#%} list="$USERV_GROUP $USERV_GID" ;;
 473       *) pat=$rest list="$USERV_USER $USERV_UID" ;;
 474     esac
 475     matchp=nil
 476     for i in $list; do case "$i" in $pat) matchp=t; break ;; esac; done
 477     case $matchp in t) verdict=$sense; break ;; esac
 478   done
 479
 480   case $verdict in
 481     forbid) echo >&2 "$quis: $op access to key \`$key' forbidden"; exit 1 ;;
 482   esac
 483 }
 484
 485 ###--------------------------------------------------------------------------
 486 ### Crypto operations for infrastructure purposes.
 487
 488 c_sysprofile () {
 489   profile=$1
 490   ## Select the profile in FILE for future crypto operations.
 491
 492   unset $(set | sed -n '/^kprop_/s/=.*$//p')
 493   reqtmp
 494   getsysprofile "$profile" >$tmp/profile
 495   readprops $tmp/profile
 496 }
 497
 498 c_gensyskey () {
 499   profile=$1 kdir=$2 knub=$3; shift 3
 500   ## Generate a system key using PROFILE; store the data in KDIR and the nub
 501   ## in KNUB.  Remaining arguments are options.
 502
 503   c_sysprofile "$profile"
 504   c_genkey "$profile" "$kdir" "$knub" : "$@"
 505 }
 506
 507 c_sysprepare () {
 508   kdir=$1
 509   readmeta "$kdir"
 510   c_sysprofile "$profile"
 511 }
 512
 513 c_sysop () {
 514   op=$1 kdir=$2; shift 1
 515   c_sysprepare "$kdir"
 516   c_$op "$@"
 517 }
 518
 519 c_sysencrypt () { c_sysop encrypt "$1" /dev/null; }
 520 c_sysdecrypt () { c_sysop decrypt "$1" "$2"; }
 521 c_syssign () { c_sysop sign "$1" "$2"; }
 522 c_sysverify () { c_sysop verify "$1" /dev/null; }
 523
 524 ###--------------------------------------------------------------------------
 525 ### Recovery operations.
 526
 527 stash () {
 528   recov=$1 label=$2
 529   ## Stash a copy of stdin encrypted under the recovery key RECOV, with a
 530   ## given LABEL.
 531   checkword "recovery key label" "$recov"
 532   checklabel "secret" "$label"
 533
 534   rdir=$KEYS/recov/$recov/current
 535   if [ ! -d $rdir/store ]; then
 536     echo >&2 "$quis: unknown recovery key \`$recov'"
 537     exit 1
 538   fi
 539   case $label in */*) mkdir -m755 -p $rdir/${label%/*} ;; esac
 540   (c_sysencrypt $rdir/store >$rdir/$label.new)
 541   mv $rdir/$label.new $rdir/$label.recov
 542 }
 543
 544 recover () {
 545   recov=$1 label=$2
 546   ## Recover a stashed secret, protected by RECOV and stored as LABEL, and
 547   ## write it to stdout.
 548   checkword "recovery key label" "$recov"
 549   checklabel "secret" "$label"
 550
 551   rdir=$KEYS/recov/$recov/current
 552   if [ ! -f $rdir/$label.recov ]; then
 553     echo >&2 "$quis: no blob for \`$label' under recovery key \`$recov'"
 554     exit 1
 555   fi
 556   reqsafe
 557   nub=$SAFE/keys.reveal/$recov.current/nub
 558   if [ ! -f $nub ]; then
 559     echo >&2 "$quis: current recovery key \`$recov' not revealed"
 560     exit 1;
 561   fi
 562   mktmp
 563   c_sysdecrypt $rdir/store $nub <$rdir/$label.recov
 564 }
 565
 566 ###--------------------------------------------------------------------------
 567 ### Help text.
 568
 569 defhelp () {
 570   read umsg
 571   usage="usage: $quis${umsg+ }$umsg"
 572   help=$(cat)
 573   case "$KEYS_HELP" in t) help; exit ;; esac
 574 }
 575
 576 help () { showhelp; }
 577 showhelp () {
 578   cat <<EOF
 579 $usage
 580
 581 $help
 582 EOF
 583 }
 584
 585 usage_err () { echo >&2 "$usage"; exit 1; }
 586
 587 ###--------------------------------------------------------------------------
 588 ### Subcommand handling.
 589
 590 version () {
 591   echo "$PACKAGE version $VERSION"
 592 }
 593
 594 cmd_help () {
 595   rc=0
 596   version
 597   case $# in
 598     0)
 599       cat <<EOF
 600
 601 $usage
 602
 603 Options:
 604   -h            Show this help text.
 605   -v            Show the program version number.
 606
 607 Commands installed:
 608 EOF
 609       cd "$KEYSLIB"
 610       for i in $prefix.*; do
 611         if [ ! -x "$i" ]; then continue; fi
 612         sed -n "/<<HELP/{n;s/^/ ${i#$prefix.} /;p;q;}" "$i"
 613       done
 614       ;;
 615     *)
 616       for i in "$@"; do
 617         echo
 618         if [ ! -x "$KEYSLIB/$prefix.$i" ]; then
 619           echo >&2 "$quis: unrecognized command \`$i'"
 620           rc=1
 621           continue
 622         elif ! KEYS_HELP=t "$KEYSLIB/$prefix.$i"; then
 623           rc=1
 624         fi
 625       done
 626       ;;
 627   esac
 628   return $rc
 629 }
 630
 631 dispatch () {
 632   case $# in 0) echo >&2 "$usage"; exit 1 ;; esac
 633   cmd=$1; shift
 634   case "$cmd" in help) cmd_help "$@"; exit ;; esac
 635   if [ ! -x "$KEYSLIB/$prefix.$cmd" ]; then
 636     echo >&2 "$quis: unrecognized command \`$cmd'"
 637     exit 1
 638   fi
 639
 640   unset KEYS_HELP
 641   exec "$KEYSLIB/$prefix.$cmd" "$@"
 642 }
 643
 644 ###----- That's all, folks --------------------------------------------------