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