2:30 p.m.
On 2018-10-19 19:18, Paul Moore wrote:
On Sun, Aug 5, 2018 at 4:33 AM Richard Guy Briggs
<rgb(a)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(a)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.
Would something like this look reasonable?
(This is on top of a patch to make contid list lock and unlock
functions.)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index be5d6eb..9428fc3 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -92,6 +92,7 @@ struct audit_contid {
struct list_head list;
u64 id;
refcount_t refcount;
+ struct rcu_head rcu;
};
extern int is_audit_feature_set(int which);
diff --git a/kernel/audit.c b/kernel/audit.c
index d5b58163..6f84c25 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -106,7 +106,6 @@
struct audit_net {
struct sock *sk;
struct list_head contid_list;
- spinlock_t contid_list_lock;
};
/**
@@ -327,26 +326,6 @@ struct list_head *audit_get_netns_contid_list(const struct net *net)
return &aunet->contid_list;
}
-static int audit_netns_contid_lock(const struct net *net)
-{
- struct audit_net *aunet = net_generic(net, audit_net_id);
-
- if (!aunet)
- return -EINVAL;
- spin_lock(aunet->contid_list_lock);
- return 0;
-}
-
-static int audit_netns_contid_unlock(const struct net *net)
-{
- struct audit_net *aunet = net_generic(net, audit_net_id);
-
- if (!aunet)
- return -EINVAL;
- spin_unlock(aunet->contid_list_lock);
- return 0;
-}
-
void audit_netns_contid_add(struct net *net, u64 contid)
{
struct list_head *contid_list = audit_get_netns_contid_list(net);
@@ -354,10 +333,9 @@ void audit_netns_contid_add(struct net *net, u64 contid)
if (!audit_contid_valid(contid))
return;
- if (audit_netns_contid_lock(net))
- return;
+ rcu_read_lock();
if (!list_empty(contid_list))
- list_for_each_entry(cont, contid_list, list)
+ list_for_each_entry_rcu(cont, contid_list, list)
if (cont->id == contid) {
refcount_inc(&cont->refcount);
goto out;
@@ -367,10 +345,16 @@ void audit_netns_contid_add(struct net *net, u64 contid)
INIT_LIST_HEAD(&cont->list);
cont->id = contid;
refcount_set(&cont->refcount, 1);
- list_add(&cont->list, contid_list);
+ list_add_rcu(&cont->list, contid_list);
}
out:
- audit_netns_contid_unlock(net);
+ rcu_read_unlock();
+}
+
+audit_free_contid_rcu(struct rcu_head *head) {
+ struct audit_contid *contid = container_of(head, struct audit_contid, rcu);
+
+ kfree(contid);
}
void audit_netns_contid_del(struct net *net, u64 contid)
@@ -380,17 +364,16 @@ void audit_netns_contid_del(struct net *net, u64 contid)
if (!audit_contid_valid(contid))
return;
- if (audit_netns_contid_lock(net))
- return;
+ rcu_read_lock();
if (!list_empty(contid_list))
- list_for_each_entry(cont, contid_list, list)
+ list_for_each_entry_rcu(cont, contid_list, list)
if (cont->id == contid) {
- list_del(&cont->list);
+ list_del_rcu(&cont->list);
if (refcount_dec_and_test(&cont->refcount))
- kfree(cont);
+ call_rcu(&cont->rcu, audit_free_contid_rcu);
break;
}
- audit_netns_contid_unlock(net);
+ rcu_read_unlock();
}
void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p)
@@ -418,15 +401,14 @@ void audit_log_netns_contid_list(struct net *net, struct
audit_context *context)
return;
}
audit_log_format(ab, "ref=net contid=");
- if (audit_netns_contid_lock(net))
- return;
- list_for_each_entry(cont, audit_get_netns_contid_list(net), list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(cont, audit_get_netns_contid_list(net), list) {
if (!first)
audit_log_format(ab, ",");
audit_log_format(ab, "%llu", cont->id);
first = false;
}
- audit_netns_contid_unlock(net);
+ rcu_read_unlock();
audit_log_end(ab);
}
EXPORT_SYMBOL(audit_log_netns_contid_list);
@@ -1674,7 +1656,6 @@ static int __net_init audit_net_init(struct net *net)
.flags = NL_CFG_F_NONROOT_RECV,
.groups = AUDIT_NLGRP_MAX,
};
-
struct audit_net *aunet = net_generic(net, audit_net_id);
aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
@@ -1684,8 +1665,6 @@ static int __net_init audit_net_init(struct net *net)
}
aunet->sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
INIT_LIST_HEAD(&aunet->contid_list);
- spin_lock_init(&aunet->contid_list_lock);
-
return 0;
}
> + 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
www.paul-moore.com
- RGB
--
Richard Guy Briggs <rgb(a)redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635