From 5ed6eae7188f3da17c8805a26c9e3a6f2289329a Mon Sep 17 00:00:00 2001 From: Andrew Clayton Date: Thu, 23 Feb 2023 12:01:14 +0000 Subject: Set a safer umask(2) when running as a daemon. When running as a daemon. unit currently sets umask(0), i.e no umask. This is resulting in various directories being created with a mode of 0777, e.g rwxrwxrwx this is currently affecting cgroup and rootfs directories, which are being created with a mode of 0777, and when running as a daemon as there is no umask to restrict the permissions. This also affects the language modules (the umask is inherited over fork(2)) whereby unless something explicitly sets a umask, files and directories will be created with full permissions, 0666 (rw-rw-rw-)/ 0777 (rwxrwxrwx) respectively. This could be an unwitting security issue. My original idea was to just remove the umask(0) call and thus inherit the umask from the executing shell/program. However there was some concern about just inheriting whatever umask was in effect. Alex suggested that rather than simply removing the umask(0) call we change it to a value of 022 (which is a common default), which will result in directories and files with permissions at most of 0755 (rwxr-xr-x) & 0644 (rw-r--r--). If applications need some other umask set, they can (as they always have been able to) set their own umask(2). Suggested-by: Alejandro Colomar Reviewed-by: Liam Crilly Signed-off-by: Andrew Clayton --- src/nxt_process.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/nxt_process.c b/src/nxt_process.c index fe9349e8..025efe70 100644 --- a/src/nxt_process.c +++ b/src/nxt_process.c @@ -1156,10 +1156,10 @@ nxt_process_daemon(nxt_task_t *task) } /* - * Reset file mode creation mask: any access - * rights can be set on file creation. + * Set a sefe umask to give at most 755/644 permissions on + * directories/files. */ - umask(0); + umask(0022); /* Redirect STDIN and STDOUT to the "/dev/null". */ -- cgit