Add a frequency file that teaches the seccomp compiler to weight the
comparison tree in favor of the most frequenctly called syscalls.
This frequency file was created by running strace against vm_conciege's
pid (e.g., "strace -p PID -ff -e raw=all -o /tmp/strace") when
performing a start and stop of a VM, deleting the trace files that
weren't for a crosvm process, passing the files to minijail's
tools/generate_seccomp_policy.py (using the -frequency option), and
combining the results of the frequency file. I rounded the #s to the
nearest multiple of 5 and only retained the syscalls that had at least
10 calls.
BUG=None
TEST=Local build and deploy. Verified that crostini VM still boots and
shuts down properly. Used scmp_bpf_disasm to disassemble a few bpf
files before and after this change to confirm that with the frequency
file the first comparision is "jge 2" (to quickly whitelist syscalls
0 and 1 ['read' and 'write']) instead of a comparison around the middle
of the range of syscall numbers that are used.
Change-Id: Icace2b5cdbcae6e51cfd67a3034a1a17fdb6d59e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2005793
Commit-Queue: Matt Delco <delco@chromium.org>
Commit-Queue: Stephen Barber <smbarber@chromium.org>
Tested-by: Matt Delco <delco@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Auto-Submit: Matt Delco <delco@chromium.org>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
