To support sigreturn with CET enabled parasite must rewind its stack
before calling sigreturn so that shadow stack will be compatible with
actual calling sequence.
In addition, calling sigreturn from top level routine
(__export_parasite_head_start) will significantly simplify the shadow
stack manipulations required to execute sigreturn.
For x86 make fini_sigreturn() return the stack pointer for the signal
frame that will be used by sigreturn and propagate that return value up
to __export_parasite_head_start.
In non-daemon mode parasite_trap_cmd() returns non-positive value
which allows to distinguish daemon and non-daemon mode and properly stop
at int3 in non-daemon mode.
Architectures other than x86 remain unchanged and will still call
sigreturn from fini_sigreturn().
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Previously, __export_parasite_cmd was located in parasite-head.S, and
__export_parasite_args located exactly at the end of the parasite blob.
This is not ideal for various reasons:
1) These two variables work together. It would be preferrable to have
them in the same location
2) This prevent us from allocating another section betweeen the parasite
blob and the args area. We'll need this to allocate a GOT table
This commit changes the allocation of these symbols from assembly/linker
script to a C file.
Moreover, the assembly entry points that invoke parasite_service()
prepares arguments with hand crafted assembly. This is unecessary.
This commit rewrite this logic with regular C code.
Note: if it wasn't for the x86 compat mode, we could remove all
parasite-head.S files and directly jump to parasite_service() via
ptrace. An int3 architecture specific equivalent could be called at the
end of parasite_service() with an inline asm statement.
Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
All those compel functions can fail by various reasons.
It may be status of the system, interruption by user or anything else.
It's really desired to handle as many PIE related errors as possible
otherwise it's hard to analyze statuses of parasite/restorer
and the C/R process.
At least warning for logs should be produced or even C/R stopped.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Providing infect functionality inside std plugin
doesn't look suite for me: the restorer has to define
dummy parasite_daemon_cmd/parasite_trap_cmd/parasite_cleanup
just to be able to compile with it.
So we have to define weak stubs right here in near future.
travis-ci: success for compel: The final infect move and install target
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
