virtiofsd: stay below fs.file-max sysctl value (CVE-2020-10717)
The system-wide fs.file-max sysctl value determines how many files can
be open. It defaults to a value calculated based on the machine's RAM
size. Previously virtiofsd would try to set RLIMIT_NOFILE to 1,000,000
and this allowed the FUSE client to exhaust the number of open files
system-wide on Linux hosts with less than 10 GB of RAM!
Take fs.file-max into account when choosing the default RLIMIT_NOFILE
value.
Fixes: CVE-2020-10717
Reported-by: Yuval Avrahami <yavrahami@paloaltonetworks.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <
20200501140644.220940-3-stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>