mirror of
https://github.com/checkpoint-restore/criu
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c7858ba42b
Add SIGTSTP signal dump and restore. Add a corresponding field in the image, save it only if a task is in the stopped state. Restore task state by sending desired stop signal if it is present in the image. Fallback to SIGSTOP if it's absent. Signed-off-by: Yuriy Vasiliev <yuriy.vasiliev@openvz.org>
123 lines
3.4 KiB
Plaintext
123 lines
3.4 KiB
Plaintext
COMPEL(1)
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==========
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include::footer.txt[]
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NAME
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----
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compel - Execute parasitic code within another process.
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SYNOPSIS
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--------
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*compel* 'hgen' ['option' ...]
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*compel* 'plugins' ['PLUGIN_NAME' ...]
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*compel* ['--compat'] 'includes' | 'cflags' | 'ldflags'
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*compel* ['--compat'] ['--static'] 'libs'
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DESCRIPTION
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------------
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*compel* is a utility to execute arbitrary code, also called parasite code,
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in the context of a foreign process. The parasitic code, once compiled with
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compel flags and packed, can be executed in the context of other tasks. Currently
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there is only one way to load the parasitic blob into victim task using libcompel.a,
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called c-header.
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ARGUMENTS
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----------
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Positional Arguments
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~~~~~~~~~~~~~~~~~~~~
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*hgen*::
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create a header from the .po file, which is the parasite binary.
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*plugins*::
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prints the plugins available.
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*ldflags*::
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prints the ldflags available to compel during linking of parasite code.
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*cflags*::
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prints the compel cflags to be used during compilation of parasitic code.
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*includes*::
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prints list of standard include directories.
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*libs*::
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prints list of static or dynamic libraries that compel can link with.
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OPTIONS
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--------
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*-f*, *--file* 'FILE'::
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Path to the binary file, 'FILE', which *compel* must turn into a header
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*-o*, *--output* 'FILE'::
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Path to the header file, 'FILE', where compel must write the resulting header.
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*-p*, *--prefix* 'NAME'::
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Specify prefix for var names
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*-l*, *--log-level* 'NUM'::
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Default log level of compel.
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*-h*, *--help*::
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Prints usage and exits.
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*-V*, *--version*::
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Prints version number of compel.
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SOURCE EXAMPLES
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----------------
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Parasitic Code
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~~~~~~~~~~~~~~
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*#include <compel/plugins/std.h>*
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*int parasite_trap_cmd(int cmd, void *args);* //gets called by compel_run_in_thread()
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*int parasite_daemon_cmd(int cmd, void *arg);* // gets called by compel_rpc_call() and compel_rpc_call_sync()
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*void parasite_cleanup(void);* //gets called on parasite unload by compel_cure()
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Infecting code
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~~~~~~~~~~~~~~
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The parasitic code is compiled and converted to a header using *compel*, and included here.
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*#include <compel/infect.h>*
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*#include "parasite.h"*
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Following steps are performed to infect the victim process:
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- stop the task: *int compel_stop_task(int pid);*
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- prepare infection handler: *struct parasite_ctl *compel_prepare(int pid);*
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- execute system call: *int compel_syscall(ctl, int syscall_nr, long *ret, int arg ...);*
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- infect victim: *int compel_infect(ctl, nr_thread, size_of_args_area);*
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- cure the victim: *int compel_cure(ctl);* //ctl pointer is freed by this call
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- Resume victim: *int compel_resume_task(pid, orig_state, state)* or
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*int compel_resume_task_sig(pid, orig_state, state, stop_signo).*
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//compel_resume_task_sig() could be used in case when victim is in stopped state.
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stop_signo could be read by calling compel_parse_stop_signo().
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*ctl* must be configured with blob information by calling *PREFIX_setup_c_header()*, with ctl as its argument.
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*PREFIX* is the argument given to *-p* when calling hgen, else it is deduced from file name.
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EXAMPLES
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---------
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To generate a header file(.h) from a parasite binary file(.po) use:
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----------
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compel hgen -f parasite.po -o parasite.h
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----------
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'parasite.po' file is obtained by compiling the parasite source with compel flags and
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linking it with the compel plugins.
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AUTHOR
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------
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The CRIU team.
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