Re: Fwd: Problem with multiple root-users (UID=0)
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On 11/16/11 00:13, Ritesh Raj Sarraf wrote:
> Hello Mike,
>
> Yes, That'd be debian-security@lists.debian.org, Cced with this email.
>
>
> Ritesh
>
> On 11/16/2011 11:15 AM, Mike Christie wrote:
>> Hey Ritesh,
>>
>> Does Debian have some sort of security list? I asked some red hat people
Did you catch (russell@coker.com.au)'s reply?
http://173.79.223.25/?l=debian-security&r=1&b=201111&w=2 Not posted
yet, but it should eventually show up here.
>>
>> and they thought removing the check for "root" and just checking for
>> UID=0 would be ok. They were not 100% sure though since we could not
>> figure out why the original maintainers check explicitly for root. So I
>> have been checking with distro people to make sure it is ok with their
>> security people.
>>
>> Thanks
>>
>> Mike
>>
>>
>>
>>
>> -------- Original Message --------
>> Subject: Problem with multiple root-users (UID=0)
>> Date: Mon, 7 Nov 2011 11:37:29 -0800 (PST)
>> From: Thomas Weichert <thomas@weichert-web.de>
>> Reply-To: open-iscsi@googlegroups.com
>> To: open-iscsi <open-iscsi@googlegroups.com>
>>
>> Hi,
>>
>> in the last few days I encountered a problem on my SLES 11.1 Linux
>> with the open-iscsi package in version 2.0-871 respectively 0.872. I
>> investigated the problem and found out that in my system there are two
>> root users with uid = 0 (sadly, this is required). Therefore I digged
>> deeper and found out that the problem most probably lies in the two
>> code snippets where "root" is defnied explicitely. Those are usr/
>> mgmt_ipc.c around line 549 with:
>>
>> if (!mgmt_peeruser(fd, user) || strncmp(user, "root", PEERUSER_MAX)) {
>> err = MGMT_IPC_ERR_ACCESS;
>> goto err;
>> }
>>
>> as well as usr/statics.c around line 7:
>>
>> static struct passwd root_pw = {
>> .pw_name = "root",
>> }
>>
>> When the Linux command `whoami` returns something different than
>> "root", open-iscsi will not work.
I think you will find that the gentent command more closely matches what
a C/C++ application would see.
It's defiantly erroneous to assume that UID(0)=='root', I can just tell
that some day PCI auditors will insist that any account called 'root'
must not be UID0 if the account exists at all.
I'm not sure what the above code is getting at. As russell pointed out
UID0 does not always mean the same as "Has access to every thing." It
would be more appropriate to create an iscsiadm group and use this to
control access instead, AKL the wheel and sudo groups... However access
to a service IMHO should be controlled with authentication, not ownership.
If instead these checks are done to prevent a future operation from
failing on a permission issue, then it sounds like the test is causing
more problems then removing them *should*. The application should
already gracefully handle any failure, so attempting to pre-discover a
permission issue should generate/assert a warning and not an error.
Thus I'm writing this email to say that your whole question sounds like
it's barking up a tree full of some fairly nasty security issues.
Either it's being to open to grant access based on UID/GID with out
further identifying the user issuing the request as a proper
authentication scheme should, keep in mind that SELINUX would have no
way of limiting access to a service like this and there could be code
run under UID0/SELINUX that's insecure. On the other hand if the code
dosn't gracefully handle failure this could also be used in a privilege
escalation attack. That covers all the reasons for code like the above
that I can think of, though there is still room for something else to be
going on. In the latter case you should be able to safely change the
result of failure here to printing a message indecating so and then
continue as though it passed, or just remove it completely. In the
former case it should be replaced with something else entirely, though
it could be left as to further limit access beyond what authentication
would do.
>>
>> As far as I understand the issue, the function call to mgmt_peeruser()
>> in mgmt_ipc.c sets the variable user to the currently logged in user
>> name and then it is compared to "root". If my root-user is named
>> differently, the strncmp function fails of course. I did not
>> investigate the code in statics.c further, whether it plays a role or
>> not, since a change to mgmt_ipc.c solves my problem.
>>
>> Is there a chance to fix this issue just by checking if the user has
>> sufficient rights, e.g. has uid=0, or is there any special reason for
>> demanding a user named root?
>>
>> Thanks a lot
>> Thomas
>>
>
>
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