file-systems: Allow specifying CIFS credentials in a file.

As files in the store and /etc/fstab are world readable, specifying the
password in the file-system record is suboptimal.  To mitigate this,
`mount.cifs' supports reading `username', `password' and `domain' options from
a file named by the `credentials' or `cred' option.

* gnu/build/file-systems.scm (mount-file-system): Read mount options from the
file specified via the `credentials' or `cred' option if specified.

Change-Id: I786c5da373fc26d45fe7a876c56a8c4854d18532
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
This commit is contained in:
vicvbcun 2024-06-26 14:15:28 +02:00 committed by Ludovic Courtès
parent b631640f3b
commit 2cbdec8bcd
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@ -39,6 +39,7 @@ (define-module (gnu build file-systems)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 regex)
#:use-module (ice-9 string-fun)
#:use-module (system foreign)
#:autoload (system repl repl) (start-repl)
#:use-module (srfi srfi-1)
@ -1187,6 +1188,39 @@ (define (mount-nfs source mount-point type flags options)
(string-append "," options)
"")))))
(define (read-cifs-credential-file file)
;; Read password, user and domain options from file
;;
;; XXX: As of version 7.0, mount.cifs strips all lines of leading
;; whitespace, parses those starting with "pass", "user" and "dom" into
;; "pass=", "user=" and "domain=" options respectively and ignores
;; everything else. To simplify the implementation, we pass those lines
;; as is. As a consequence, the "password2" option can be specified in a
;; credential file with the expected semantics (see:
;; https://issues.guix.gnu.org/71594#3).
(with-input-from-file file
(lambda ()
(let loop
((next-line (read-line))
(lines '()))
(match next-line
((? eof-object?)
lines)
((= string-trim line)
(loop (read-line)
(cond
((string-prefix? "pass" line)
;; mount.cifs escapes commas in the password by doubling
;; them
(cons (string-replace-substring line "," ",,")
lines))
((or (string-prefix? "user" line)
(string-prefix? "dom" line))
(cons line lines))
;; Ignore all other lines.
(else
lines)))))))))
(define (mount-cifs source mount-point type flags options)
;; Source is of form "//<server-ip-or-host>/<service>"
(let* ((regex-match (string-match "//([^/]+)/(.+)" source))
@ -1195,6 +1229,9 @@ (define (mount-cifs source mount-point type flags options)
;; Match ",guest,", ",guest$", "^guest,", or "^guest$," not
;; e.g. user=foo,pass=notaguest
(guest? (string-match "(^|,)(guest)($|,)" options))
(credential-file (and=> (string-match "(^|,)(credentials|cred)=([^,]+)(,|$)"
options)
(cut match:substring <> 3)))
;; Perform DNS resolution now instead of attempting kernel dns
;; resolver upcalling. /sbin/request-key does not exist and the
;; kernel hardcodes the path.
@ -1219,6 +1256,11 @@ (define (mount-cifs source mount-point type flags options)
;; ignores it. Also, avoiding excess commas
;; when deleting is a pain.
(string-append "," options)
"")
(if credential-file
;; The "credentials" option is ignored too.
(string-join (read-cifs-credential-file credential-file)
"," 'prefix)
"")))))
(let* ((type (file-system-type fs))