Re: [PATCH ghak90 (was ghak32) V4 09/10] audit: NETFILTER_PKT: record each container ID associated with a netNS

Paul Moore
2018-10-19T23:18:54Z

On Sun, Aug 5, 2018 at 4:33 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> Add audit container identifier auxiliary record(s) to NETFILTER_PKT
> event standalone records. Iterate through all potential audit container
> identifiers associated with a network namespace.
>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
> include/linux/audit.h | 5 +++++
> kernel/audit.c | 26 ++++++++++++++++++++++++++
> net/netfilter/xt_AUDIT.c | 12 ++++++++++--
> 3 files changed, 41 insertions(+), 2 deletions(-)

...

> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 9a02095..8755f4d 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -169,6 +169,8 @@ extern int audit_log_contid(struct audit_context *context,
> extern void audit_netns_contid_add(struct net *net, u64 contid);
> extern void audit_netns_contid_del(struct net *net, u64 contid);
> extern void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p);
> +extern void audit_log_netns_contid_list(struct net *net,
> + struct audit_context *context);
>
> extern int audit_update_lsm_rules(void);
>
> @@ -228,6 +230,9 @@ static inline void audit_netns_contid_del(struct net *net, u64 contid)
> { }
> static inline void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p)
> { }
> +static inline void audit_log_netns_contid_list(struct net *net,
> + struct audit_context *context)
> +{ }
>
> #define audit_enabled AUDIT_OFF
> #endif /* CONFIG_AUDIT */
> diff --git a/kernel/audit.c b/kernel/audit.c
> index c5fed3b..b23711c 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -392,6 +392,32 @@ void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p)
> audit_netns_contid_add(new->net_ns, contid);
> }
>
> +void audit_log_netns_contid_list(struct net *net, struct audit_context *context)
> +{
> + spinlock_t *lock = audit_get_netns_contid_list_lock(net);
> + struct audit_buffer *ab;
> + struct audit_contid *cont;
> + bool first = true;
> +
> + /* Generate AUDIT_CONTAINER record with container ID CSV list */
> + ab = audit_log_start(context, GFP_ATOMIC, AUDIT_CONTAINER);
> + if (!ab) {
> + audit_log_lost("out of memory in audit_log_netns_contid_list");
> + return;
> + }
> + audit_log_format(ab, "contid=");
> + spin_lock(lock);
> + list_for_each_entry(cont, audit_get_netns_contid_list(net), list) {
> + if (!first)
> + audit_log_format(ab, ",");
> + audit_log_format(ab, "%llu", cont->id);
> + first = false;
> + }
> + spin_unlock(lock);

This is looking like potentially a lot of work to be doing under a
spinlock, not to mention a single spinlock that is shared across CPUs.
Considering that I expect changes to the list to be somewhat
infrequent, this might be a good candidate for a RCU based locking
scheme.

> + audit_log_end(ab);
> +}
> +EXPORT_SYMBOL(audit_log_netns_contid_list);
>
> void audit_panic(const char *message)
> {
> switch (audit_failure) {
> diff --git a/net/netfilter/xt_AUDIT.c b/net/netfilter/xt_AUDIT.c
> index af883f1..44fac3f 100644
> --- a/net/netfilter/xt_AUDIT.c
> +++ b/net/netfilter/xt_AUDIT.c
> @@ -71,10 +71,13 @@ static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
> {
> struct audit_buffer *ab;
> int fam = -1;
> + struct audit_context *context;
> + struct net *net;
>
> if (audit_enabled == AUDIT_OFF)
> - goto errout;
> - ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
> + goto out;
> + context = audit_alloc_local(GFP_ATOMIC);
> + ab = audit_log_start(context, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
> if (ab == NULL)
> goto errout;
>
> @@ -104,7 +107,12 @@ static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
>
> audit_log_end(ab);
>
> + net = xt_net(par);
> + audit_log_netns_contid_list(net, context);
> +
> errout:
> + audit_free_context(context);
> +out:
> return XT_CONTINUE;
> }
>

--
paul moore