On Wed, Mar 27, 2019 at 09:12:02PM -0400, Richard Guy Briggs wrote:

On 2019-03-27 23:42, Ondrej Mosnacek wrote:

quoted

On Fri, Mar 15, 2019 at 7:35 PM Richard Guy Briggs [off-list ref] wrote:

quoted

Audit events could happen in a network namespace outside of a task
context due to packets received from the net that trigger an auditing
rule prior to being associated with a running task.  The network
namespace could be in use by multiple containers by association to the
tasks in that network namespace.  We still want a way to attribute
these events to any potential containers.  Keep a list per network
namespace to track these audit container identifiiers.

Add/increment the audit container identifier on:
- initial setting of the audit container identifier via /proc
- clone/fork call that inherits an audit container identifier
- unshare call that inherits an audit container identifier
- setns call that inherits an audit container identifier
Delete/decrement the audit container identifier on:
- an inherited audit container identifier dropped when child set
- process exit
- unshare call that drops a net namespace
- setns call that drops a net namespace

See: https://github.com/linux-audit/audit-kernel/issues/92
See: https://github.com/linux-audit/audit-testsuite/issues/64
See: https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID
Signed-off-by: Richard Guy Briggs <redacted>
---
 include/linux/audit.h | 19 ++++++++++++
 kernel/audit.c        | 86 +++++++++++++++++++++++++++++++++++++++++++++++++--
 kernel/nsproxy.c      |  4 +++
 3 files changed, 106 insertions(+), 3 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index fa19fa408931..70255c2dfb9f 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h

@@ -27,6 +27,7 @@
 #include <linux/ptrace.h>
 #include <linux/namei.h>  /* LOOKUP_* */
 #include <uapi/linux/audit.h>
+#include <linux/refcount.h>

 #define AUDIT_INO_UNSET ((unsigned long)-1)
 #define AUDIT_DEV_UNSET ((dev_t)-1)

@@ -99,6 +100,13 @@ struct audit_task_info {

 extern struct audit_task_info init_struct_audit;

+struct audit_contid {
+       struct list_head        list;
+       u64                     id;
+       refcount_t              refcount;

Hm, since we only ever touch the refcount under a spinlock, I wonder
if we could just make it a regular unsigned int (we don't need the
atomicity guarantees). OTOH, refcount_t comes with some extra overflow
checking, so it's probably better to leave it as is...

Since the update is done using rcu-safe methods, do we even need the
spin_lock?  Neil?  Paul?

Yes, we do.  Rcu-safe methods only apply to read side operations, we still need
traditional mutual exclusion on the write side of the operation.  That is to say
we need to protect the list against multiple writers at the same time, and for
that we need a spin lock.

Neil