We need to continue the traced process even if there is a fatal
error. Otherwise, sudo will appear to hang as the running process
is left in PTRACE_EVENT stop.
Unlike PTRACE_GETREGSET, PTRACE_GETREGS requires that we manually
map registers from 64-bit to 32-bit layouts when running, e.g. a
32-bit binary from a 64-bit sudo process.
We can skip the policy check for the execve(2) of the initial command
since it has already been check. Otherwise, we would log the command
twice. When using fexecve(2) due to a digest check, there should
be no need to skip the initial command since it will be executed
via execveat(2) not execve(2). However, on older kernels without
execveat(2), glibc will emulate fexecve(2) using /proc which will
result in the extra log entry.
This fixes a race condition in ptrace-based intercept mode when
running the command in a pty. It was possible for the monitor to
receive SIGCHLD when the command sent itself SIGSTOP before the
main sudo process did.
