John A. Sullivan III wrote: > On Mon, 2009-01-26 at 07:26 -0500, John A. Sullivan III wrote: > >> On Mon, 2009-01-26 at 06:28 -0500, John A. Sullivan III wrote: >> >>> On Mon, 2009-01-26 at 20:25 +1100, Declan Mullen wrote: >>> >>>> Hi >>>> >>>> When I ssh into my Linux server, the login succeeds but I notice that I >>>> get the following type of entry appended to the auth.log : >>>> >>>> Jan 26 17:10:45 maxv1 sshd[32624]: error writing /proc/self/oom_adj: >>>> Permission denied >>>> >>>> What are the implications of the sshd not being able to write to the >>>> oom_adj ? Ie Is this error significant or should I just ignore it ? >>>> >>>> The sshd's write is failing because the server I'm logging into is a >>>> VServer guest/virtual server, and the VServer virtualisation technology >>>> places restrictions on what can be written to the /proc filesystem from >>>> within the guest. >>>> >>>> The guest server OS is Debian Lenny and the sshd versions is >>>> "1:5.1p1-5". Within the sshd_config Privilege Separation is turned on. >>>> >>>> The host server's kernel is Lenny's "linux-source-2.6.26" (version >>>> "2.6.26-13") with Lenny's vserver patches applied from >>>> "linux-patch-debian-2.6.26" (version "2.6.26-13"). The host's >>>> util-vserver package is version "0.30.216~r2772-6". The host's >>>> "vserver-debiantools" package is version "0.6.3". >>>> >>> <snip> >>> I'm facing the same issue and would like for the guest to be able to set >>> oom_adj. I would imagine this is done by editing the vprocunhidefiles >>> file However, before doing so, I'd like to ask the list if there is a >>> security issue in doing so. I suppose a savvy guest could make their >>> system a hog - the last one to have any processes shut down in an out of >>> memory condition thus creating an availability problem but I wouldn't >>> imagine it creates a data confidentiality or integrity problem. Is this >>> true? Thanks - John >>> >> Oops! That's not true. OpenSSH appears to want to create this /proc >> entry. vprocunhide doesn't seem to solve that problem! - John >> > > By the way, if one wants to stop the error message, one can > edit /etc/init.d/ssh and comment out the calls to adjust_oom in the > start and restart sections of the init script - John > I have just noticed that in /etc/default/ssh : # OOM-killer adjustment for sshd (see # linux/Documentation/filesystems/proc.txt; lower values reduce likelihood # of being killed, while -17 means the OOM-killer will ignore sshd; set to # the empty string to skip adjustment) SSHD_OOM_ADJUST=-17 I've modified this file to set SSHD_OOM_ADJUST to a null string, and now sshd no longer attempts to write to oom_adj and the error messages no longer occur.