From d50b66a6c387930377f94c9362343cca8ddc0886 Mon Sep 17 00:00:00 2001 From: Mark Johnston Date: Tue, 6 Apr 2021 14:57:57 -0400 Subject: [PATCH] mount: Disallow mounting over a jail root Discussed with: jamie Approved by: so Security: CVE-2020-25584 Security: FreeBSD-SA-21:10.jail_mount (cherry picked from commit 110ebf0886825227d03d2ab17139a8741272aef5) --- sys/kern/vfs_mount.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index afbb3e313d7..a7db7a3dd9d 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -844,10 +844,10 @@ vfs_domount_first( /* * If the jail of the calling thread lacks permission for this type of - * file system, deny immediately. + * file system, or is trying to cover its own root, deny immediately. */ - if (jailed(td->td_ucred) && !prison_allow(td->td_ucred, - vfsp->vfc_prison_flag)) { + if (jailed(td->td_ucred) && (!prison_allow(td->td_ucred, + vfsp->vfc_prison_flag) || vp == td->td_ucred->cr_prison->pr_root)) { vput(vp); return (EPERM); } -- 2.45.0