root_as_sibling was used in criu_signals_setup(), but was only defined later
(when forking the root task for the first time). This meant that the
SA_NOCLDSTOP was never masked off, which meant SIGCHLD was never delivered
after ptracing the root task. Thus, when the a child of the root task died
(e.g. from cr_system), the root task sat in PTRACE_STOP, and the restore task
never PTRACE_CONT'd, resulting in a deadlock.

Instead, we only unmask SA_NOCLDSTOP right before we PTRACE_SEIZE, after the
value is defined.

v2: re-work the condition for CLONE_PARENT
v3: move unmasking of SA_NOCLDSTOP to restore_root_task
v4: keep all the comments in the original code
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Since the command line for checkpointing and restoring Docker containers
is very long and there are some manual steps involved before restoring
a container, it's much easier to use a shell script to automate the work.

One would simply do:

$ sudo docker_cr.sh -c
$ sudo docker_cr.sh -r
Signed-off-by: Saied Kazemi <saied@google.com>
Acked-by: Filipe Brandenburger <filbranden@google.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

zdtm.sh with zero iterations of dumping/restoring checks correctness of
tests.

$ bash test/zdtm.sh -i 0 zdtm/inotify00
Output file: /root/git/orig/criu/test/zdtm/live/static/inotify00.out
------------------------------------------------------------------------------
19:16:29.601:  6905: 	unlink 02       : event      0x200 -> IN_DELETE
19:16:29.602:  6905: 	unlink 02       : event      0x200 -> IN_DELETE
19:16:29.602:  6905: 	unlink 02       : event        0x8 -> IN_CLOSE_WRITE
19:16:29.602:  6905: 	unlink 02       : event        0x8 -> IN_CLOSE_WRITE
19:16:29.602:  6905: 	unlink 02       : event      0x400 -> IN_DELETE_SELF
19:16:29.602:  6905: 	unlink 02       : event     0x8000 -> IN_IGNORED
19:16:29.602:  6905: 	unlink 02       : read  6 events
19:16:29.614:  6905: 	after           : event        0x8 -> IN_CLOSE_WRITE
19:16:29.614:  6905: 	after           : read  1 events
19:16:29.614:  6905: FAIL: inotify00.c:217: Unhandled events in emask 0x200 -> IN_DELETE (errno = 11 (Resource temporarily unavailable))
------------------------------------- END -------------------------------------
================================= ERROR OVER =================================

This patch removes logic about linked files, because it's useless.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

BTRFS returns subvolume dev-id instead of superblock dev-id,
in such case return device obtained from mountinfo (ie subvolume0).

v2: fix up devices only for btrfs files.
v3: use phys_stat_dev_match instead of phys_stat_resolve_dev
v4: fix cosmetic whims

Reported-by: Mr Jenkins
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

11: POSIX  ADVISORY  WRITE 1 b6:a4111:136512 0 EOF
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

It turns out that we can't be too strict about
queued events -- criu itself generates a number
of them and there is no clear way yet how to resolve
this situation. So defer "strict" mode for now
but print a warning.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

When service starts page server all the preparations (log, wdir, img dir, etc.)
happen in parent task, then we fork page server.

This is OK for now, but when we will serve several requests per connection, all
these resources would be leaked in parent.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

The problem with several requests is that criu leaks resources after
doing dump/restore. It's OK since process exits anyway, but for
multy requests per connection it's better to audit this thing.

For now -- allow to do requests after the page-server-start one only.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

That's preparation to "several requests per connection" patch.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

It is called from prepare_cgroup_sfd() and cr_restore_tasks().

+ criu restore --file-locks --tcp-established --evasive-devices --link-remap --root /var/lib/vz/root/101 --restore-detached --action-script /usr/local/libexec/vzctl/scripts/vps-rst-env -D /vz/dump/Dump.101 -o restore.log -vvvv --pidfile /var/lib/vzctl/vepid/101
*** Error in `criu': double free or corruption (fasttop): 0x00000000006bcd40 ***

Program terminated with signal 6, Aborted.
Missing separate debuginfos, use: debuginfo-install glibc-2.17-20.fc19.x86_64 libgcc-4.8.3-1.fc19.x86_64 protobuf-c-0.15-7.fc19.x86_64
(gdb) bt
 #0  0x00007ffff72179e9 in raise () from /lib64/libc.so.6
 #1  0x00007ffff72190f8 in abort () from /lib64/libc.so.6
 #2  0x00007ffff7257d17 in __libc_message () from /lib64/libc.so.6
 #3  0x00007ffff725f0b8 in _int_free () from /lib64/libc.so.6
 #4  0x0000000000426971 in cr_restore_tasks () at cr-restore.c:1833
 #5  0x0000000000418426 in main (argc=<optimized out>, argv=0x7fffffffeb38, envp=<optimized out>) at crtools.c:479
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

To show which events are coming and flush events before dump as required by new fsnotify mode.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

If a controller is mounted during dumping processes, criu may fail with error:
Error (cgroup.c:768): cg: Set 3 is not subset of 2

so lets create all test controllers before executing tests.

Reported-by: Mr Jenkins
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Events are not dumped/restored. An idea of ignoring them isn't good.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

There is a potential attack here where if someone is restoring something and
criu write the pid to a file the attacker controls, the attacker can then
re-write that to whatever pid they want. ciru should instead open the file with
O_EXCL so that the restore fails if the file exists.

We don't need O_TRUNC here since we're O_EXCL-ing the file.
Reported-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

If we need to check if current loglevel will suppress
our messagess (say you need to run pr_debug in a cycle)
we can use this helper to eliminate unneded calls.

Like
  if (!pr_quelled(LOG_DEBUG)) {
    ... do something specific to LOG_DEBUG ...
  }
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

All marks are collected in a list and then they are written in
the eventpoll image as a repeated field.

This images merge reduces the amount of image files criu
generates and may simplify the fix of mentioned above issue

v2: save the original order of entries
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

All marks are collected in a list and then they are written in
the fanotify image as a repeated field.

This images merge reduces the amount of image files criu
generates and may simplify the fix of mentioned above issue

v2: don't leak fe.mark_entry
v3: save the original order of marks
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

All watch descriptors are collected in a list and then
they are written in inotify image as a repeated field.

This images merge reduces the amount of image files criu
generates and may simplify the fix of mentioned above issue.

v2: use free_inotify_wd_entry() instead of xfree in dump_one_inotify()
v3: don't leak ie.wd_entry
v4: save the original order of watchers
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

The swrk action is turning out to be a cool thing. We can
spawn criu with swrk action with some FD being open, then
ask for dump/pre-dump/page-server telling it that some
descriptor it needs is "out there".

This patch lets us specify that the page server communication
channel is already in criu's fdtable.

TODO: teach regular service to accept fd via service socket.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Here we define new api to be used in plugins.

 - Plugin should provide a descriptor with help of
   CR_PLUGIN_REGISTER macro, or in case if plugin require
   no init/exit functions -- with CR_PLUGIN_REGISTER_DUMMY.

 - Plugin should define a plugin hook with help of
   CR_PLUGIN_REGISTER_HOOK macro.

 - Now init/exit functions of plugins takes @stage
   argument which tells plugin which stage of criu
   it's been called on dump/restore. For exit it
   also takes @ret which allows plugin to know if
   something went wrong and it needs to cleanup
   own resources.

The idea behind is to not limit plugins authors with names
of functions they might need to use for particular hook.

Such new API deprecates olds plugins structure but to keep
backward compatibility we will provide a tiny layer of
additional code to support old plugins for at least a couple
of release cycles.

For example a trivial plugin might look like

 | #include <sys/types.h>
 | #include <sys/stat.h>
 | #include <fcntl.h>
 | #include <libgen.h>
 | #include <errno.h>
 |
 | #include <sys/socket.h>
 | #include <linux/un.h>
 |
 | #include <stdio.h>
 | #include <stdlib.h>
 | #include <string.h>
 | #include <unistd.h>
 |
 | #include "criu-plugin.h"
 | #include "criu-log.h"
 |
 | static int dump_ext_file(int fd, int id)
 | {
 |	pr_info("dump_ext_file: fd %d id %d\n", fd, id);
 |	return 0;
 | }
 |
 | CR_PLUGIN_REGISTER_DUMMY("trivial")
 | CR_PLUGIN_REGISTER_HOOK(CR_PLUGIN_HOOK__DUMP_EXT_FILE, dump_ext_file)
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

 - use custom multiline comments style
 - ending #endif comment
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

These guys may have pids that are not met in pstree.
This is not the reason for skipping those, try to
resolve flocks anyway.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Criu may re-lock the lock, thus spoiling the pid, so compare
the file inode number instead.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Return 0 in a success case
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

After patches, that dump locks w/o dfds array, we can even
not allocate one when we don't need it.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

If we open a file, lock one, fork, then close and
open the file in parent again, lock should 'slide'
to the child process anyway.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Inherited flock is the one that a task got from its parent.
In case parent closes the corresponding fd, the /proc/locks
still shows the parent pid, while the lock is owned by child.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Shared here means that a flock is visible from two tasks -- the
owner one and its child.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

We have a problem with file locks (bug #2512) -- the /proc/locks
file shows the ID of lock creator, not the owner. Thus, if the
creator died, but holder is still alive, criu fails to dump the
lock held by latter task.

The proposal is to find who _might_ hold the lock by checking
for dev:inode pairs on lock vs file descriptors being dumped.
If the creator of the lock is still alive, then he will take
the priority.

One thing to note about flocks -- these belong to file entries,
not to tasks. Thus, when we meet one, we should check whether
the flock is really held by task's FD by trying to set yet
another one. In case of success -- lock really belongs to fd
we dump, in case it doesn't trylock should fail.

At the very end -- walk the list of locks and dump them all at
once, which is possible by merge of per-task file-locks images
into one global one.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Same reason as for previous patch.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Currently we keep the lock type (posix/flock) till the
time we dump it, then "decode" it into binary value.
I will need the easy-to-check one early, so parse the
kind in proc_parse.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>