Do not watch for post-execve SIGTRAP if PTRACE_O_TRACEEXEC is enabled

If PTRACE_O_TRACEEXEC option is enabled, then post-execve SIGTRAPs are
suppressed and we can safely skip -ENOSYS heuristics.  This partially
reverts commits v4.9-258-g8e398b6 and v4.9-261-gd70c41d.

* syscall.c (syscall_fixup_on_sysenter): Skip if PTRACE_O_TRACEEXEC
flag is set in ptrace_setoptions.  Remove all SECCOMP_RET_ERRNO
workarounds as they are not needed when PTRACE_O_TRACEEXEC is not
supported by the kernel.
1 file changed