Issue with 'test' command and network shares on non-domain network

[cy.20.superconductor@xoxy.net]

Hello all,

I've been seeing a problem with permissions checks using v. 1.5.9 of 
cygwin on network shares on machines which are not part of a domain with 
smbntsec set,  any command that performs an explicit access check seems 
to always think that access  is denied.

I'll pick the 'test' command as an example but it isn't the only command 
that suffers the problem. I have the SIDs of the remote machine's users 
and groups in /etc/passwd and /etc/group, so ls -l shows up meaningful 
file owners and permissions etc. This means I have more than one user 
SID mapped onto the same UID (which doesn't seem to bother cygwin). The 
problem occurs with commands that do an explicit access check like 
'test' and 'rm', these all fail (e.g. rm always thinks files are write 
protected), this is something that didn't use to happen in Cygwin 1.3 
(ish). 

The way Cygwin performs access control checks seems to have changed over 
the past year or two, I've been doing some digging and this is my 
understanding of the problem: in older versions when cygwin wanted to 
perform an permissions check, it used to stat the file, call 
get_nt_attribute, and presumably calculate permissions mapping itself 
using the mapped uid and gid in /etc/passwd and /etc/group, newer 
versions call the win32 function _AccessCheck_ using the process token. 
This is fine for the local machine or another machine on the same 
domain, but doesn't work for machines with a "workgroup" type 
relationship using network shares, because (as far as I can tell) this 
requires a different user token (because I am "logged on" to the remote 
machine via the share using a user on the remote machine) which appears 
to be rather difficult to obtain. Previously this sort of functionality 
could be made to work by filling in the remote machine's SIDs/UIDs in 
the local /etc/passwd.

As a result of this 'test' gives misleading results and 'rm' complains 
it can't delete a file you've just created because it thinks it is 
write-protected. So for example although ls -l will accurately reflect 
the executable bits set for a file, test -x will fail because of the 
failed _AccessCheck_ call. So now it seems I will have to turn smbntsec 
off to stop basic things like being able to delete a file that has just 
been created from going wrong.

Is there anything that can be done to switch to old-style access checks, 
or some way of making the new system work in a non-domain network 
environment ?

Thanks,

Paul




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