Date: Sun, 05 Sep 2021 12:29:35 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 258287] [jail] Easily exhaust host kernel's numvnodes or dp_dirty_total in a jail which may cause Dos attack Message-ID: <bug-258287-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D258287 Bug ID: 258287 Summary: [jail] Easily exhaust host kernel's numvnodes or dp_dirty_total in a jail which may cause Dos attack Product: Base System Version: Unspecified Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: 1203405394@qq.com Hello=EF=BC=8Cwe find two underlying jails security issues to exhaust host'= s kernel's resources which may cause Dos attack. The first one is we can easily exhaust the host's `numvnodes` and reach the `maxvnodes` limit in a jail. Thecsecond one is we can keep produce dirty data in a jail and make the `dp_dirty_total` reachs `zfs_dirty_data_max` limit. As a result, other writ= ing request may delay. Reproduction steps: 1. We set up jails following the FreeBSD's handbook. 2. Use `ezjail-admin create` commands to create a normal malicious jail. 3. For numvnodes, we just keep creating directories using `Mkdir` command in the malicious jail. Host's numvnodes will keep rising until it reach the maxvnodes limit. 4. For `dp_dirty_total`, we observed that the `zfs_dirty_data_max` limit is 800Mi, we keep writing data to a file at high speed. As a result, the host's `dp_dirty_total` will reach the `zfs_dirty_data_max` limit and cause other writing request being delayed. Although it seems that there is no serious performance and functional impac= t on host, I wonder if there should be some ways to limit the per-jail `vnodes` = or `dp_dirty_total` like `rctl` which can avoid malicious jails to launch Dos attack. --=20 You are receiving this mail because: You are the assignee for the bug.=
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