Error: Cannot update core dump limit

[Arran Cudbard-Bell]

> On 7 Jul 2016, at 04:20, Jakob Hirsch <jh at plonk.de> wrote:
> 
> Alan DeKok wrote on 2016-07-06 15:13:
>>>> Tue Jul  5 13:16:42 2016 : Error: Cannot update core dump limit: Operation not permitted
>>>> Tue Jul  5 13:16:42 2016 : Info: Core dumps are enabled
>>>> Tue Jul  5 13:16:42 2016 : Info: Debugger not attached
>>> Any idea what's going wrong here?
>>  The server is probably changing UID, and trying to update the core limit after that.
> 
> I guess that's not a problem (since FR does a prctl(PR_SET_DUMPABLE, 1)
> after the UID/GID changes):
> 
>> setgroups(1, [106])                     = 0
>> setgid(106)                             = 0
>> mkdir("/var/log/freeradius", 0700)   = -1 EEXIST (File exists)
>> geteuid()                               = 0
>> setresuid(4294967295, 104, 0)           = 0
>> geteuid()                               = 104
>> setrlimit(RLIMIT_CORE, {rlim_cur=0, rlim_max=0}) = 0
>> open("/var/log/freeradius/radius.log", O_WRONLY|O_CREAT|O_APPEND, 0640) = 3
>> fchown(3, 104, 106)                     = 0
>> prctl(PR_SET_DUMPABLE, 1)               = 0
>> setrlimit(RLIMIT_CORE, {rlim_cur=RLIM_INFINITY, rlim_max=RLIM_INFINITY}) = -1 EPERM (Operation not permitted)
> 
> but FR uses setrlimit() with rlim_max=0, and you can only lower
> rlim_max, but not raise it (unless you have the CAP_SYS_RESOURCE
> capability).

OK... So there's probably an issue there.  Could we get the stack trace so it's clear what logic is being executed.

There's only two calls to setrlimit in the server...

> I don't know what the call setrlimit(RLIMIT_CORE,
> {rlim_cur=0, rlim_max=0}) is good for...

It disables core dumping.

-Arran

Arran Cudbard-Bell <a.cudbardb at freeradius.org>
FreeRADIUS Development Team

FD31 3077 42EC 7FCD 32FE 5EE2 56CF 27F9 30A8 CAA2

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