Bug 974

Summary:	incorrect use of syntax_check() leads to command line verification uncertainity
Product:	Sudo	Reporter:	Endre Szabo <endre.szabo>
Component:	Visudo	Assignee:	Todd C. Miller <Todd.Miller>
Status:	RESOLVED FIXED
Severity:	normal	CC:	endre.szabo
Priority:	low
Version:	1.9.6
Hardware:	All
OS:	All

Description Endre Szabo 2021-04-20 09:17:32 MDT

When things work just fine:

# visudo -sc
/etc/sudoers: parsed OK
/etc/sudoers.d/openvpn: bad permissions, should be mode 0440
/etc/sudoers.d/zfs: parsed OK

When things go bad: (fflag is set)

# visudo -sc -f /etc/sudoers
/etc/sudoers: parsed OK
/etc/sudoers.d/openvpn: parsed OK
/etc/sudoers.d/zfs: parsed OK
# visudo -sc /etc/sudoers
/etc/sudoers: parsed OK
/etc/sudoers.d/openvpn: parsed OK
/etc/sudoers.d/zfs: parsed OK

My guess:

check_syntax() is called with wrong arguments.

check_syntax() function signature is:

check_syntax(const char *file, bool quiet, bool strict, bool oldperms)

how is it called instead:

check_syntax(sudoers_file, quiet, strict, fflag) ? 0 : 1;

note the 'fflag' vs 'oldperms'

Comment 1 Todd C. Miller 2021-04-20 09:23:35 MDT

This is intentional.  The permission check is not performed when the -f option is specified.  The intent of the -f flag is to make it possible to check the syntax of a sudoers file before it is installed.  For example, if sudoers is stored in git or as part of some other configuration management setup.

Comment 2 Endre Szabo 2021-04-20 09:34:26 MDT

Minds blown, thanks for the heads up.