Permission problem with luci-base.json when build-system uses "umask 0022"

[torte71]

Targets: System independent (seen on raspberry pi3, gl-ar150 and wr842)
Version: git-head (probably in earlier versions as well)
Module: luci-base

See also here: freifunk-berlin/firmware#431

When building luci-base on a system with a default umask 0022, luci will not be usable for non-root users in the resulting image (non-root access is enabled e.g. in the freifunk package).
For non-root users, it will just display a "500 internal server error", because ubusd requires the file "/usr/share/acl.d/luci-base.json"[1] to be not group-readable[2]. As a result, access to ubus/system/board will not be allowed, leading to a NIL value for the boardinfo object in "/usr/lib/lua/luci/view/themes/bootstrap/header.htm"[3], what causes a crash, when trying to access its "hostname"[4] property.

The reason is, that the "install" section in "luci.mk"[5] does not set the required permission - it just copies the directories, retaining the permissions, that the files have from "git clone". If you are lucky to be compiling on a host with a "umask 0002" setting, the luci-base.json will have rw-r--r-- permission and everything works fine. On a system with "umask 0022" (this is nothing unusual), it will have rw-rw-r-- permissions after the checkout, resulting in a non-usable luci in the final image.

As a workaround, one can issue "umask 0002" before "git clone"ing. To really solve it, luci.mk may use "chmod" or "$(INSTALL_DATA)" on this file to ensure, the file gets installed with the correct permissions.

How to reproduce:

• Build lede/openwrt with these steps:
  • a) With error: "umask 0022 ; git clone https://git.lede-project.org/source.git lede"
  • b) Without error: "umask 0002 ; git clone https://git.lede-project.org/source.git lede"
  • ./scripts/feeds update -a
  • ./scripts/feeds install -a
  • make menuconfig
  • select LuCI/Collections/luci
  • select LuCI/Modules/luci-mod-freifunk - to see luci break - without it, only the ubusd output will show the permission issue
  • make
• Install the image
• With luci-mod-freifunk: Open http://192.168.1.1 to see the 500-internal-server error (and via logread: "Tue Jan 9 23:48:09 2018 daemon.err uhttpd[1009]: A runtime error occured: [string "/usr/lib/lua/luci/view/themes/bootstrap/hea..."]:150: attempt to index local 'boardinfo' (a nil value)")
• Without luci-mod-freifunk: Login via ssh. When running "killall ubusd" on the routers console, you will see following output from "logread -f": "Wed Jan 10 00:13:04 2018 daemon.err ubusd[1644]: /usr/share/acl.d/luci-base.json has wrong permissions"

(Please note, that the Freifunk-module is only used to easily demonstrate the consequences of this issue. The output from restarting ubusd shows, that the permission problem already exists in a vanilla luci-base installation).

[1] affected file "/usr/share/acl.d/luci-base.json"
https://github.com/openwrt/luci/tree/master/modules/luci-base/root/usr/share/acl.d

[2] permission check in ubusd
https://git.lede-project.org/?p=project/ubus.git;a=blob;f=ubusd_acl.c;h=4b72663d25aa983cb65b10fae8ba029b099c7c45;hb=HEAD#l406

[3] NIL value for boardinfo = util.ubus("system", "board")
https://github.com/openwrt/luci/blob/master/themes/luci-theme-bootstrap/luasrc/view/themes/bootstrap/header.htm#L14

[4] crash accessing boardinfo.hostname
https://github.com/openwrt/luci/blob/master/themes/luci-theme-bootstrap/luasrc/view/themes/bootstrap/header.htm#L162

[5] "install" section from luci.mk
https://github.com/openwrt/luci/blob/master/luci.mk#L169

[jow-]

I am unable to verify this problem here.
Compiled this test program:

#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(int argc, char *argv[])
{
	struct stat st;

	if (stat("/usr/share/acl.d/luci-base.json", &st)) {
		printf("stat failed\n");
		return 1;
	}

	if (st.st_uid || st.st_gid) {
		printf("wrong owner\n");
		return 1;
	}

	if (st.st_mode & (S_IWOTH | S_IWGRP | S_IXOTH)) {
		printf("has wrong permissions\n");
		return 1;
	}

	printf("permissions okay\n");
	return 0;
}

Ran it on a target device:

root@jj:~# ls -lh /usr/share/acl.d/luci-base.json
-rw-r--r--    1 root     root          91 Jul  2  2017 /usr/share/acl.d/luci-base.json
root@jj:~# /tmp/test 
permissions okay
root@jj:~# 

[jow-]

You probably swapped your with/without error cases. Builds with umask != 022 are known to be broken, OpenWrt added a prereq check due to this, see https://github.com/openwrt/openwrt/blob/master/include/prereq-build.mk#L25

The problem you raise here is not specific to LuCI and will affect a lot of other packages as well so I am not sure if it makes sense to add workarounds or checks to address this specific arbitrary case.

[torte71]

Oops, indeed I swapped those values.
But looking at the grep from the prereq test: This would return true for 0022 and 0002 (and some more).
That explains, why I never encountered that message.

[jow-]

This needs to be solved in OpenWrt buildroot and/or the host system.