Make use of Capsicum to protect kdump(1), as it might be used to parse data
from untrusted sources:
- Sandbox kdump(1) using capability mode.
- Limit stdin descriptor (where opened file is moved to) to only
CAP_READ and CAP_FSTAT rights.
- Limit stdout descriptor to only CAP_WRITE, CAP_FSTAT and CAP_IOCTL.
Plus limit allowed ioctls to TIOCGETA only, which is needed for
isatty() to work.
- Limit stderr descriptor to only CAP_WRITE and CAP_FSTAT. In addition
if the -s option is not given, grant CAP_IOCTL right, but allow for
TIOCGWINSZ ioctl only, as we need screen width to dump the data.
- Before entering capability mode call catopen("libc", NL_CAT_LOCALE),
which opens message catalogs and caches data, so that strerror(3)
and strsignal(3) can work in a sandbox.
Sponsored by: The FreeBSD Foundation
Discussed with: rwatson
16e12aa3c2