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d4c02f2eb1
Why should we have self-unmapping code in parasite?
It looks like, we can drop this code using simple sys_unmap()
injection (like that I did for `criu exec` action and for cases where we
failed to insert parasite by some reason, but still need to unmap remotes).
It's an RFC, so just a suggestion - maybe I miss something you have in
mind - please, describe that/those things.
My motivation is:
- less code, defined commands for PIE, one BUG() less, one jump to PIE less
- I'm making one 64-bit parasite on x86 instead of two 32 and 64 bit.
It works (branch 32-one-parasite) with long-jump in the beginning to
64-bit code from 32-bit task.
On parasite curing it sig-returns from 64-bit parasite to 32-bit task,
this point we're trapping in CRIU. After that we command parasite to
unmap itself, so it long-jumps again to parasite 64-bit code, unmaps,
we caught task after sys_unmap and the task is with 64-bit CS.
We can't set 32-bit registers after this - kernel checks that
registers set is the same on PTRACE_SETREGSET:
> > static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
> > struct iovec *kiov)
...
> > if (!regset || (kiov->iov_len % regset->size) != 0)
> > return -EINVAL;
So, to return again to 32-bit task I need sigreturn() again or add
long-jump with 32-bit CS.
I've disable that for 32-bit testing with (in compel_cure_remote):
- if (ctl->addr_cmd) {
+ if (ctl->addr_cmd && user_regs_native(&ctl->orig.regs)) {
And it works. It also works for native tasks, so why should we keep it?
travis-ci: success for compel: kill self-unmap in parasite
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
47 lines
1,011 B
C
47 lines
1,011 B
C
#ifndef __COMPEL_RPC_H__
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#define __COMPEL_RPC_H__
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struct ctl_msg {
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uint32_t cmd; /* command itself */
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uint32_t ack; /* ack on command */
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int32_t err; /* error code on reply */
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};
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#define ctl_msg_cmd(_cmd) \
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(struct ctl_msg){.cmd = _cmd, }
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#define ctl_msg_ack(_cmd, _err) \
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(struct ctl_msg){.cmd = _cmd, .ack = _cmd, .err = _err, }
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/*
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* NOTE: each command's args should be arch-independed sized.
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* If you want to use one of the standard types, declare
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* alternative type for compatible tasks in parasite-compat.h
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*/
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enum {
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PARASITE_CMD_IDLE = 0,
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PARASITE_CMD_ACK,
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PARASITE_CMD_INIT_DAEMON,
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/*
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* This must be greater than INITs.
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*/
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PARASITE_CMD_FINI,
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__PARASITE_END_CMDS,
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};
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struct parasite_init_args {
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int32_t h_addr_len;
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struct sockaddr_un h_addr;
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int32_t log_level;
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uint64_t sigreturn_addr;
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uint64_t sigframe; /* pointer to sigframe */
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futex_t daemon_connected;
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};
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struct parasite_unmap_args {
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uint64_t parasite_start;
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uint64_t parasite_len;
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};
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#endif
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