RE: [PATCH 0/3] [RFC] Write dump into container's filesystem for pipe_type core_pattern

From: Zhao Lei
Date: Tue Apr 26 2016 - 23:03:32 EST


Ping

Thanks
Zhaolei

> From: Zhao Lei [mailto:zhaolei@xxxxxxxxxxxxxx]
> Sent: Friday, April 15, 2016 6:47 PM
> To: linux-kernel@xxxxxxxxxxxxxxx
> Cc: containers@xxxxxxxxxxxxxxxxxxxxxxxxxx; Eric W. Biederman
> <ebiederm@xxxxxxxxxxxx>; Mateusz Guzik <mguzik@xxxxxxxxxx>;
> Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>; Zhao Lei
> <zhaolei@xxxxxxxxxxxxxx>
> Subject: [PATCH 0/3] [RFC] Write dump into container's filesystem for pipe_type
> core_pattern
>
> In current system, when we set core_pattern to a pipe, both pipe program
> and program's output are in host's filesystem.
> But when we set core_pattern to a file, the container will write dump
> into container's filesystem.
>
> For example, when we set following core_pattern:
> # echo "|/my_dump_pipe %s %c %p %u %g %t
> e" >/proc/sys/kernel/core_pattern
> and trigger a segment fault in a container, my_dump_pipe is searched from
> host's filesystem, and it will write coredump into host's filesystem too.
>
> In a privileged container, user can destroy host system by following
> command:
> # # In a container
> # echo "|/bin/dd of=/boot/vmlinuz" >/proc/sys/kernel/core_pattern
> # make_dump
>
> Actually, all operation in a container should not change host's
> environment, the container should use core_pattern as its private setting.
> In detail, in core dump action:
> 1: Search pipe program in container's fs namespace.
> 2: Run pipe program in container's fs namespace to write coredump to it.
>
> I rewrited this patch from origional:
>
> http://www.gossamer-threads.com/lists/linux/kernel/2395715?do=post_view_
> flat
> and changed the impliment way and function detail discussed in:
>
> http://www.gossamer-threads.com/lists/linux/kernel/2397602?nohighlight=1#
> 2397602
>
> Changes against previous impliment:
> 1: Avoid forking thread from the crach process.
> Suggested-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> 2: To keep compatibility with current code, if user hadn't change
> core_pattern in container, the dump file will still write to
> the host filesystem.
> Suggested-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
>
> Zhao Lei (3):
> [RFC] Save dump_root into pid_namespace
> [RFC] Make dump_pipe thread possilbe to select the rootfs
> [RFC] Write dump into container's filesystem for pipe_type
> core_pattern
>
> fs/coredump.c | 19 ++++++++++++++++++-
> fs/fs_struct.c | 25 ++++++++++++++++---------
> include/linux/fs_struct.h | 3 ++-
> include/linux/kmod.h | 4 +++-
> include/linux/pid_namespace.h | 3 +++
> include/linux/sched.h | 5 +++--
> init/do_mounts_initrd.c | 3 ++-
> init/main.c | 4 ++--
> kernel/fork.c | 34 ++++++++++++++++++++--------------
> kernel/kmod.c | 13 ++++++++-----
> kernel/kthread.c | 3 ++-
> kernel/pid.c | 1 +
> kernel/pid_namespace.c | 6 ++++++
> kernel/sysctl.c | 30 ++++++++++++++++++++++++++----
> lib/kobject_uevent.c | 3 ++-
> security/keys/request_key.c | 2 +-
> 16 files changed, 115 insertions(+), 43 deletions(-)
>
> --
> 1.8.5.1