lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 26 Jan 2012 19:32:23 +0100 From: Ingo Molnar <mingo@...e.hu> To: Arnaldo Carvalho de Melo <acme@...radead.org> Cc: linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>, David Daney <david.daney@...ium.com>, Frederic Weisbecker <fweisbec@...il.com>, Jan Beulich <jbeulich@...e.com>, Joerg Roedel <joerg.roedel@....com>, Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>, Mike Galbraith <efault@....de>, Namhyung Kim <namhyung.kim@....com>, Paul Mackerras <paulus@...ba.org>, Peter Zijlstra <peterz@...radead.org>, Srikar Dronamraju <srikar@...ux.vnet.ibm.com>, Stephane Eranian <eranian@...gle.com> Subject: Re: Fixing perf top --user shortcoming was: Re: [GIT PULL 0/9] perf/core improvements and fixes * Arnaldo Carvalho de Melo <acme@...radead.org> wrote: > > > ptrace_may_access(task, PTRACE_MODE_READ) fails for some > > > tasks owned by the user because, IIRC, in > > > __ptrace_may_access: > > > Which tasks are these, are they privileged in any sense? > > IIRC one of them was a child of sshd, that runs as root and > then changes the child ownership to the user logging in. It's probably privileged then - or at least not sufficiently deprivileged. Skipping them ought to be the right solution - it's not like such tasks tend to create a lot of overhead worth profiling. They are also not debuggable via gdb so they are not part of the user's development session and such. > I'll continue investigation but probably for now the first > thing to do is to just remove them from the thread_map when > they return -EPERM. Yeah. Maybe warn about them in verbose mode or such. > > If yes and if most of the 'real' tasks a user have can be > > profiled just fine then i think we should just skip the > > privileged tasks and not abort the profiling session? > > Yeah, that can be done, while debugging I'll emit a warning > with the resulting thread_map of "special tasks" to figure out > what makes them special. Ok, sounds great! Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists