Re: [PATCH ghak90 V8 12/16] audit: contid check descendancy and nesting

On Tue, Dec 31, 2019 at 2:51 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > Require the target task to be a descendant of the container > orchestrator/engine. > > You would only change the audit container ID from one set or inherited > value to another if you were nesting containers. > > If changing the contid, the container orchestrator/engine must be a > descendant and not same orchestrator as the one that set it so it is not > possible to change the contid of another orchestrator's container. > > Since the task_is_descendant() function is used in YAMA and in audit, > remove the duplication and pull the function into kernel/core/sched.c > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > include/linux/sched.h | 3 +++ > kernel/audit.c | 44 ++++++++++++++++++++++++++++++++++++-------- > kernel/sched/core.c | 33 +++++++++++++++++++++++++++++++++ > security/yama/yama_lsm.c | 33 --------------------------------- > 4 files changed, 72 insertions(+), 41 deletions(-) ... > diff --git a/kernel/audit.c b/kernel/audit.c > index f7a8d3288ca0..ef8e07524c46 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -2603,22 +2610,43 @@ int audit_set_contid(struct task_struct *task, u64 contid) > oldcontid = audit_get_contid(task); > read_lock(&tasklist_lock); > /* Don't allow the contid to be unset */ > - if (!audit_contid_valid(contid)) > + if (!audit_contid_valid(contid)) { > rc = -EINVAL; > + goto unlock; > + } > /* Don't allow the contid to be set to the same value again */ > - else if (contid == oldcontid) { > + if (contid == oldcontid) { > rc = -EADDRINUSE; > + goto unlock; > + } > /* if we don't have caps, reject */ > - else if (!capable(CAP_AUDIT_CONTROL)) > + if (!capable(CAP_AUDIT_CONTROL)) { > rc = -EPERM; > - /* if task has children or is not single-threaded, deny */ > - else if (!list_empty(&task->children)) > + goto unlock; > + } > + /* if task has children, deny */ > + if (!list_empty(&task->children)) { > rc = -EBUSY; > - else if (!(thread_group_leader(task) && thread_group_empty(task))) > + goto unlock; > + } > + /* if task is not single-threaded, deny */ > + if (!(thread_group_leader(task) && thread_group_empty(task))) { > rc = -EALREADY; > - /* if contid is already set, deny */ > - else if (audit_contid_set(task)) > + goto unlock; > + } It seems like the if/else-if conversion above should be part of an earlier patchset.

> + /* if task is not descendant, block */ > + if (task == current) { > + rc = -EBADSLT; > + goto unlock; > + } > + if (!task_is_descendant(current, task)) { > + rc = -EXDEV; > + goto unlock; > + } I understand you are trying to provide a unique error code for each failure case, but this is getting silly. Let's group the descendent checks under the same error code.

> + /* only allow contid setting again if nesting */ > + if (audit_contid_set(task) && audit_contid_isowner(task)) > rc = -ECHILD; Should that be "!audit_contid_isowner()"?

paul moore