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-rw-r--r--gnu/build/accounts.scm6
-rw-r--r--gnu/build/activation.scm37
2 files changed, 27 insertions, 16 deletions
diff --git a/gnu/build/accounts.scm b/gnu/build/accounts.scm
index c43ce85b60..8687446aa6 100644
--- a/gnu/build/accounts.scm
+++ b/gnu/build/accounts.scm
@@ -51,6 +51,7 @@
group-entry-gid
group-entry-members
+ %password-lock-file
write-group
write-passwd
write-shadow
@@ -224,6 +225,11 @@ each field."
(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
diff --git a/gnu/build/activation.scm b/gnu/build/activation.scm
index cfdf17df0f..c6c7e7fd3b 100644
--- a/gnu/build/activation.scm
+++ b/gnu/build/activation.scm
@@ -22,6 +22,7 @@
#:use-module (gnu build accounts)
#:use-module (gnu build linux-boot)
#:use-module (guix build utils)
+ #:use-module ((guix build syscalls) #:select (with-file-lock))
#:use-module (ice-9 ftw)
#:use-module (ice-9 match)
#:use-module (ice-9 vlist)
@@ -129,22 +130,26 @@ group records) are all available."
;; Allow home directories to be created under /var/lib.
(mkdir-p "/var/lib")
- (let-values (((groups passwd shadow)
- (user+group-databases users groups)))
- (write-group groups)
- (write-passwd passwd)
- (write-shadow shadow)
-
- ;; Home directories of non-system accounts are created by
- ;; 'activate-user-home'.
- (for-each make-home-directory system-accounts)
-
- ;; Turn shared home directories, such as /var/empty, into root-owned,
- ;; read-only places.
- (for-each (lambda (directory)
- (chown directory 0 0)
- (chmod directory #o555))
- (duplicates (map user-account-home-directory system-accounts)))))
+ ;; Take same lock as libc's 'lckpwdf' (but without a timeout) while we read
+ ;; and write the databases. This ensures there's no race condition with
+ ;; other tools that might be accessing it at the same time.
+ (with-file-lock %password-lock-file
+ (let-values (((groups passwd shadow)
+ (user+group-databases users groups)))
+ (write-group groups)
+ (write-passwd passwd)
+ (write-shadow shadow)))
+
+ ;; Home directories of non-system accounts are created by
+ ;; 'activate-user-home'.
+ (for-each make-home-directory system-accounts)
+
+ ;; Turn shared home directories, such as /var/empty, into root-owned,
+ ;; read-only places.
+ (for-each (lambda (directory)
+ (chown directory 0 0)
+ (chmod directory #o555))
+ (duplicates (map user-account-home-directory system-accounts))))
(define (activate-user-home users)
"Create and populate the home directory of USERS, a list of tuples, unless