Re: [RFC PATCH V1 01/12] audit: add container id

On 03/15/2018 11:58 PM, Richard Guy Briggs wrote: > On 2018-03-15 16:27, Stefan Berger wrote: > > On 03/01/2018 02:41 PM, Richard Guy Briggs wrote: > > > Implement the proc fs write to set the audit container ID of a process, > > > emitting an AUDIT_CONTAINER record to document the event. > > > > > > This is a write from the container orchestrator task to a proc entry of > > > the form /proc/PID/containerid where PID is the process ID of the newly > > > created task that is to become the first task in a container, or an > > > additional task added to a container. > > > > > > The write expects up to a u64 value (unset: 18446744073709551615). > > > > > > This will produce a record such as this: > > > type=UNKNOWN[1333] msg=audit(1519903238.968:261): op=set pid=596 uid=0 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 auid=0 tty=pts0 ses=1 opid=596 old-contid=18446744073709551615 contid=123455 res=0 > > > > > > The "op" field indicates an initial set. The "pid" to "ses" fields are > > > the orchestrator while the "opid" field is the object's PID, the process > > > being "contained". Old and new container ID values are given in the > > > "contid" fields, while res indicates its success. > > > > > > It is not permitted to self-set, unset or re-set the container ID. A > > > child inherits its parent's container ID, but then can be set only once > > > after. > > > > > > See: https://github.com/linux-audit/audit-kernel/issues/32 > > > > > > > > > /* audit_rule_data supports filter rules with both integer and string > > > * fields. It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > > index 4e0a4ac..0ee1e59 100644 > > > --- a/kernel/auditsc.c > > > +++ b/kernel/auditsc.c > > > @@ -2073,6 +2073,92 @@ int audit_set_loginuid(kuid_t loginuid) > > > return rc; > > > } > > > > > > +static int audit_set_containerid_perm(struct task_struct *task, u64 containerid) > > > +{ > > > + struct task_struct *parent; > > > + u64 pcontainerid, ccontainerid; > > > + pid_t ppid; > > > + > > > + /* Don't allow to set our own containerid */ > > > + if (current == task) > > > + return -EPERM; > > > + /* Don't allow the containerid to be unset */ > > > + if (!cid_valid(containerid)) > > > + return -EINVAL; > > > + /* if we don't have caps, reject */ > > > + if (!capable(CAP_AUDIT_CONTROL)) > > > + return -EPERM; > > > + /* if containerid is unset, allow */ > > > + if (!audit_containerid_set(task)) > > > + return 0; > > I am wondering whether there should be a check for the target process that > > will receive the containerid to not have CAP_SYS_ADMIN that would otherwise > > allow it to arbitrarily unshare()/clone() and leave the set of namespaces > > that may make up the container whose containerid we assign here? > This is a reasonable question. This has been debated and I understood > the conclusion was that without a clear definition of a "container", the > task still remains in that container that just now has more > sub-namespaces (in the case of hierarchical namespaces), we don't want > to restrict it in such a way and that allows it to create nested > containers. I see setns being more problematic if it could switch to > another existing namespace that was set up by the orchestrator for a > different container. The coming v2 patchset acknowledges this situation > with the network namespace being potentially shared by multiple > containers. Are you going to post v2 soon? We would like to build on top of it for IMA namespacing and auditing inside of IMA namespaces.

Stefan