On Tue, Jan 28, 2025 at 04:21:13PM +0100, Christophe Leroy wrote:

Le 28/01/2025 à 10:16, Dmitry V. Levin a écrit :

quoted

PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of
system calls the tracee is blocked in.

This API allows ptracers to obtain and modify system call details
in a straightforward and architecture-agnostic way.

Current implementation supports changing only those bits of system call
information that are used by strace, namely, syscall number, syscall
arguments, and syscall return value.

How do you handle changes related to syscalls that call 
force_successful_syscall_return() ?

I don't see why these syscalls would need any special treatment.
If a tracer wants to set an error status for a syscall that cannot return
an error, it's up to the tracer to face the consequences.
Tracers can do it now via PTRACE_SETREGS* anyway.


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ldv