guix - Wojtek's customized Guix

diff options
Diffstat (limited to 'tests/guix-repl.sh')
0 files changed, 0 insertions, 0 deletions
69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019, 2021 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu build accounts)
  #:use-module (guix records)
  #:use-module (guix combinators)
  #:use-module (gnu system accounts)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-26)
  #:use-module (ice-9 match)
  #:use-module (ice-9 vlist)
  #:use-module (ice-9 rdelim)
  #:export (password-entry
            password-entry?
            password-entry-name
            password-entry-uid
            password-entry-gid
            password-entry-real-name
            password-entry-directory
            password-entry-shell

            shadow-entry
            shadow-entry?
            shadow-entry-name
            shadow-entry-minimum-change-period
            shadow-entry-maximum-change-period
            shadow-entry-change-warning-time
            shadow-entry-maximum-inactivity
            shadow-entry-expiration

            group-entry
            group-entry?
            group-entry-name
            group-entry-gid
            group-entry-members

            %password-lock-file
            write-group
            write-passwd
            write-shadow
            read-group
            read-passwd
            read-shadow

            %id-min
            %id-max
            %system-id-min
            %system-id-max

            user+group-databases))

;;; Commentary:
;;;
;;; This modules provides functionality equivalent to the C library's
;;; <shadow.h>, <pwd.h>, and <grp.h> routines, as well as a subset of the
;;; functionality of the Shadow command-line tools.  It can parse and write
;;; /etc/passwd, /etc/shadow, and /etc/group.  It can also take care of UID
;;; and GID allocation in a way similar to what 'useradd' does.
;;;
;;; The benefit is twofold: less code is involved, and the ID allocation
;;; strategy and state preservation is made explicit.
;;;
;;; Code:


;;;
;;; Machinery to define user and group databases.
;;;

(define-syntax serialize-field
  (syntax-rules (serialization)
    ((_ entry (field get (serialization ->string string->) _ ...))
     (->string (get entry)))
    ((_ entry (field get _ ...))
     (get entry))))

(define-syntax deserialize-field
  (syntax-rules (serialization)
    ((_ str (field get (serialization ->string string->) _ ...))
     (string-> str))
    ((_ str (field get _ ...))
     str)))

(define-syntax let/fields
  (syntax-rules ()
    ((_ (((name get attributes ...) rest ...) lst) body ...)
     (let ((l lst))
       (let ((name (deserialize-field (car l)
                                      (name get attributes ...))))
         (let/fields ((rest ...) (cdr l)) body ...))))
    ((_ (() lst) body ...)
     (begin body ...))))

(define-syntax define-database-entry
  (syntax-rules (serialization)
    "Define a record data type, as per 'define-record-type*', with additional
information on how to serialize and deserialize the whole database as well as
each field."
    ((_ <record> record make-record record?
        (serialization separator entry->string string->entry)
        fields ...)
     (let-syntax ((field-name
                   (syntax-rules ()
                     ((_ (name _ (... ...))) name))))
       (define-record-type* <record> record make-record
         record?
         fields ...)

       (define (entry->string entry)
         (string-join (list (serialize-field entry fields) ...)
                      (string separator)))

       (define (string->entry str)
         (let/fields ((fields ...) (string-split str #\:))
                     (make-record (field-name fields) ...)))))))


(define number->string*
  (match-lambda
    ((? number? number) (number->string number))
    (_ "")))

(define (false-if-string=? false-string)
  (lambda (str)
    (if (string=? str false-string)
        #f
        str)))

(define (string-if-false str)
  (lambda (obj)
    (if (not obj) str obj)))

(define (comma-separated->list str)
  (string-tokenize str (char-set-complement (char-set #\,))))

(define (list->comma-separated lst)
  (string-join lst ","))


;;;
;;; Database definitions.
;;;

(define-database-entry <password-entry>           ;<pwd.h>
  password-entry make-password-entry
  password-entry?
  (serialization #\: password-entry->string string->password-entry)

  (name       password-entry-name)
  (password   password-entry-password
              (serialization (const "x") (const #f))
              (default "x"))
  (uid        password-entry-uid
              (serialization number->string string->number))
  (gid        password-entry-gid
              (serialization number->string string->number))
  (real-name  password-entry-real-name
              (default ""))
  (directory  password-entry-directory)
  (shell      password-entry-shell
              (default "/bin/sh")))

(define-database-entry <shadow-entry>             ;<shadow.h>
  shadow-entry make-shadow-entry
  shadow-entry?
  (serialization #\: shadow-entry->string string->shadow-entry)

  (name                  shadow-entry-name)       ;string
  (password              shadow-entry-password    ;string | #f
                         (serialization (string-if-false "!")
                                        (false-if-string=? "!"))
                         (default #f))
  (last-change           shadow-entry-last-change ;days since 1970-01-01
                         (serialization number->string* string->number)
                         (default 0))
  (minimum-change-period shadow-entry-minimum-change-period
                         (serialization number->string* string->number)
                         (default #f))            ;days | #f
  (maximum-change-period shadow-entry-maximum-change-period
                         (serialization number->string* string->number)
                         (default #f))            ;days | #f
  (change-warning-time   shadow-entry-change-warning-time
                         (serialization number->string* string->number)
                         (default #f))            ;days | #f
  (maximum-inactivity    shadow-entry-maximum-inactivity
                         (serialization number->string* string->number)
                         (default #f))             ;days | #f
  (expiration            shadow-entry-expiration
                         (serialization number->string* string->number)
                         (default #f))            ;days since 1970-01-01 | #f
  (flags                 shadow-entry-flags       ;"reserved"
                         (serialization number->string* string->number)
                         (default #f)))

(define-database-entry <group-entry>              ;<grp.h>
  group-entry make-group-entry
  group-entry?
  (serialization #\: group-entry->string string->group-entry)

  (name            group-entry-name)
  (password        group-entry-password
                   (serialization (string-if-false "x")
                                  (false-if-string=? "x"))
                   (default #f))
  (gid             group-entry-gid
                   (serialization number->string string->number))
  (members         group-entry-members
                   (serialization list->comma-separated comma-separated->list)
                   (default '())))

(define %password-lock-file
  ;; The password database lock file used by libc's 'lckpwdf'.  Users should
  ;; grab this lock with 'with-file-lock' when they access the databases.
  "/etc/.pwd.lock")

(define (database-writer file mode entry->string)
  (lambda* (entries #:optional (file-or-port file))
    "Write ENTRIES to FILE-OR-PORT.  When FILE-OR-PORT is a file name, write
to it atomically and set the appropriate permissions."
    (define (write-entries port)
      (for-each (lambda (entry)
                  (display (entry->string entry) port)
                  (newline port))
                (delete-duplicates entries)))

    (if (port? file-or-port)
        (write-entries file-or-port)
        (let* ((template (string-append file-or-port ".XXXXXX"))
               (port     (mkstemp! template)))
          (dynamic-wind
            (const #t)
            (lambda ()
              (chmod port mode)
              (write-entries port)

              (fsync port)
              (close-port port)
              (rename-file template file-or-port))
            (lambda ()
              (unless (port-closed? port)
                (close-port port))
              (when (file-exists? template)
                (delete-file template))))))))

(define write-passwd
  (database-writer "/etc/passwd" #o644 password-entry->string))
(define write-shadow
  (database-writer "/etc/shadow" #o600 shadow-entry->string))
(define write-group
  (database-writer "/etc/group" #o644 group-entry->string))

(define (database-reader file string->entry)
  (lambda* (#:optional (file-or-port file))
    (define (read-entries port)
      (let loop ((entries '()))
        (match (read-line port)
          ((? eof-object?)
           (reverse entries))
          (line
           (loop (cons (string->entry line) entries))))))

    (if (port? file-or-port)
        (read-entries file-or-port)
        (call-with-input-file file-or-port
          read-entries))))

(define read-passwd
  (database-reader "/etc/passwd" string->password-entry))
(define read-shadow
  (database-reader "/etc/shadow" string->shadow-entry))
(define read-group
  (database-reader "/etc/group" string->group-entry))


;;;
;;; Building databases.
;;;

(define-record-type* <allocation>
  allocation make-allocation
  allocation?
  (ids            allocation-ids (default vlist-null))
  (next-id        allocation-next-id (default %id-min))
  (next-system-id allocation-next-system-id (default %system-id-max)))

;; Trick to avoid name clashes...
(define-syntax %allocation (identifier-syntax allocation))

;; Minimum and maximum UIDs and GIDs (from find_new_uid.c and find_new_gid.c
;; in Shadow.)
(define %id-min 1000)
(define %id-max 60000)

(define %system-id-min 100)
(define %system-id-max 999)

(define (system-id? id)
  (and (> id %system-id-min)
       (<= id %system-id-max)))

(define (user-id? id)
  (and (>= id %id-min)
       (< id %id-max)))

(define* (allocate-id assignment #:key system?)
  "Return two values: a newly allocated ID, and an updated <allocation> record
based on ASSIGNMENT.  If SYSTEM? is true, return a system ID."
  (define next
    ;; Return the next available ID, looping if necessary.
    (if system?
        (lambda (id)
          (let ((next-id (- id 1)))
            (if (< next-id %system-id-min)
                %system-id-max
                next-id)))
        (lambda (id)
          (let ((next-id (+ id 1)))
            (if (>= next-id %id-max)
                %id-min
                next-id)))))

  (let loop ((id (if system?
                     (allocation-next-system-id assignment)
                     (allocation-next-id assignment))))
    (if (vhash-assv id (allocation-ids assignment))
        (loop (next id))
        (let ((taken (vhash-consv id #t (allocation-ids assignment))))
          (values (if system?
                      (allocation (inherit assignment)
                                  (next-system-id (next id))
                                  (ids taken))
                      (allocation (inherit assignment)
                                  (next-id (next id))
                                  (ids taken)))
                  id)))))

(define* (reserve-ids allocation ids #:key (skip? #t))
  "Mark the numbers listed in IDS as reserved in ALLOCATION.  When SKIP? is
true, start allocation after the highest (or lowest, depending on whether it's
a system ID allocation) number among IDS."
  (%allocation
   (inherit allocation)
   (next-id (if skip?
                (+ (reduce max
                           (- (allocation-next-id allocation) 1)
                           (filter user-id? ids))
                   1)
                (allocation-next-id allocation)))
   (next-system-id
    (if skip?
        (- (reduce min
                   (+ 1 (allocation-next-system-id allocation))
                   (filter system-id? ids))
           1)
        (allocation-next-system-id allocation)))
   (ids (fold (cut vhash-consv <> #t <>)
              (allocation-ids allocation)
              ids))))

(define (allocated? allocation id)
  "Return true if ID is already allocated as part of ALLOCATION."
  (->bool (vhash-assv id (allocation-ids allocation))))

(define (lookup-procedure lst key)
  "Return a lookup procedure for the elements of LST, calling KEY to obtain
the key of each element."
  (let ((table (fold (lambda (obj table)
                       (vhash-cons (key obj) obj table))
                     vlist-null
                     lst)))
    (lambda (key)
      (match (vhash-assoc key table)
        (#f #f)
        ((_ . value) value)))))

(define* (allocate-groups groups members
                          #:optional (current-groups '()))
  "Return a list of group entries for GROUPS, a list of <user-group>.  Members
for each group are taken from MEMBERS, a vhash that maps group names to member
names.  GIDs and passwords found in CURRENT-GROUPS, a list of group entries,
are reused."
  (define gids
    ;; Mark all the currently-used GIDs and the explicitly requested GIDs as
    ;; reserved.
    (reserve-ids (reserve-ids (allocation)
                              (map group-entry-gid current-groups))
                 (filter-map user-group-id groups)
                 #:skip? #f))

  (define previous-entry
    (lookup-procedure current-groups group-entry-name))

  (reverse
   (fold2 (lambda (group result allocation)
            (let ((name         (user-group-name group))
                  (password     (user-group-password group))
                  (requested-id (user-group-id group))
                  (system?      (user-group-system? group)))
              (let*-values (((previous)
                             (previous-entry name))
                            ((allocation id)
                             (cond
                              ((number? requested-id)
                               (values (reserve-ids allocation
                                                    (list requested-id))
                                       requested-id))
                              (previous
                               (values allocation
                                       (group-entry-gid previous)))
                              (else
                               (allocate-id allocation
                                            #:system? system?)))))
                (values (cons (group-entry
                               (name name)
                               (password
                                (if previous
                                    (group-entry-password previous)
                                    password))
                               (gid id)
                               (members (vhash-fold* cons '() name members)))
                              result)
                        allocation))))
          '()
          gids
          groups)))

(define* (allocate-passwd users groups #:optional (current-passwd '()))
  "Return a list of password entries for USERS, a list of <user-account>.
Take GIDs from GROUPS, a list of group entries.  Reuse UIDs from
CURRENT-PASSWD, a list of password entries, when possible; otherwise allocate
new UIDs."
  (define uids
    (reserve-ids (reserve-ids (allocation)
                              (map password-entry-uid current-passwd))
                 (filter-map user-account-uid users)
                 #:skip? #f))

  (define previous-entry
    (lookup-procedure current-passwd password-entry-name))

  (define (group-id name)
    (or (any (lambda (entry)
               (and (string=? (group-entry-name entry) name)
                    (group-entry-gid entry)))
             groups)
        (error "group not found" name)))

  (reverse
   (fold2 (lambda (user result allocation)
            (let ((name         (user-account-name user))
                  (requested-id (user-account-uid user))
                  (group        (user-account-group user))
                  (real-name    (user-account-comment user))
                  (directory    (user-account-home-directory user))
                  (shell        (user-account-shell user))
                  (system?      (user-account-system? user)))
              (let*-values (((previous)
                             (previous-entry name))
                            ((allocation id)
                             (cond
                              ((number? requested-id)
                               (values (reserve-ids allocation
                                                    (list requested-id))
                                       requested-id))
                              (previous
                               (values allocation
                                       (password-entry-uid previous)))
                              (else
                               (allocate-id allocation
                                            #:system? system?)))))
                (values (cons (password-entry
                               (name name)
                               (uid id)
                               (directory directory)
                               (gid (if (number? group) group (group-id group)))

                               ;; Users might change their name to something
                               ;; other than what the sysadmin chose, with
                               ;; 'chfn'.  Thus consider it "stateful".
                               (real-name (if (and previous (not system?))
                                              (password-entry-real-name previous)
                                              real-name))

                               ;; Do not reuse the shell of PREVIOUS since (1)
                               ;; that could lead to confusion, and (2) the
                               ;; shell might have been GC'd.  See
                               ;; <https://lists.gnu.org/archive/html/guix-devel/2019-04/msg00478.html>.
                               (shell shell))
                              result)
                        allocation))))
          '()
          uids
          users)))

(define* (days-since-epoch #:optional (current-time current-time))
  "Return the number of days elapsed since the 1st of January, 1970."
  (let* ((now   (current-time time-utc))
         (epoch (make-time time-utc 0 0))
         (diff  (time-difference now epoch)))
    (quotient (time-second diff) (* 24 3600))))

(define* (passwd->shadow users passwd #:optional (current-shadow '())
                         #:key (current-time current-time))
  "Return a list of shadow entries for the password entries listed in PASSWD.
Reuse shadow entries from CURRENT-SHADOW when they exist, and take the initial
password from USERS."
  (define previous-entry
    (lookup-procedure current-shadow shadow-entry-name))

  (define now
    (days-since-epoch current-time))

  (map (lambda (user passwd)
         (or (previous-entry (password-entry-name passwd))
             (shadow-entry (name (password-entry-name passwd))
                           (password (user-account-password user))
                           (last-change now))))
       users passwd))

(define (empty-if-not-found thunk)
  "Call THUNK and return the empty list if that throws to ENOENT."
  (catch 'system-error
    thunk
    (lambda args
      (if (= ENOENT (system-error-errno args))
          '()
          (apply throw args)))))

(define* (user+group-databases users groups
                               #:key
                               (current-passwd
                                (empty-if-not-found read-passwd))
                               (current-groups
                                (empty-if-not-found read-group))
                               (current-shadow
                                (empty-if-not-found read-shadow))
                               (current-time current-time))
  "Return three values: the list of group entries, the list of password
entries, and the list of shadow entries corresponding to USERS and GROUPS.
Preserve stateful bits from CURRENT-PASSWD, CURRENT-GROUPS, and
CURRENT-SHADOW: UIDs, GIDs, passwords, user shells, etc."
  (define members
    ;; Map group name to user names.
    (fold (lambda (user members)
            (fold (cute vhash-cons <> (user-account-name user) <>)
                  members
                  (user-account-supplementary-groups user)))
          vlist-null
          users))

  (define group-entries
    (allocate-groups groups members current-groups))

  (define passwd-entries
    (allocate-passwd users group-entries current-passwd))

  (define shadow-entries
    (passwd->shadow users passwd-entries current-shadow
                    #:current-time current-time))

  (values group-entries passwd-entries shadow-entries))

context:
space:
mode: