[PATCH ghak90 (was ghak32) V4 08/10] audit: add support for containerid to network namespaces

Richard Guy Briggs
2018-07-31T20:07:43Z

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 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 <rgb@redhat.com>
---
include/linux/audit.h | 17 ++++++++++
kernel/audit.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/auditsc.c | 8 ++++-
kernel/nsproxy.c | 4 +++
4 files changed, 114 insertions(+), 1 deletion(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 5580c25..9a02095 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -26,6 +26,7 @@
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <uapi/linux/audit.h>
+#include <linux/refcount.h>

#define AUDIT_INO_UNSET ((unsigned long)-1)
#define AUDIT_DEV_UNSET ((dev_t)-1)
@@ -87,6 +88,12 @@ struct audit_field {
u32 op;
};

+struct audit_contid {
+ struct list_head list;
+ u64 id;
+ refcount_t refcount;
+};
+
extern int is_audit_feature_set(int which);

extern int __init audit_register_class(int class, unsigned *list);
@@ -159,6 +166,9 @@ extern void audit_log_task_info(struct audit_buffer *ab,
struct task_struct *tsk);
extern int audit_log_contid(struct audit_context *context,
char *op, u64 contid);
+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 int audit_update_lsm_rules(void);

@@ -212,6 +222,13 @@ static inline void audit_log_task_info(struct audit_buffer *ab,
static inline int audit_log_contid(struct audit_context *context,
char *op, u64 contid)
{ }
+static inline void audit_netns_contid_add(struct net *net, u64 contid)
+{ }
+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)
+{ }
+
#define audit_enabled AUDIT_OFF
#endif /* CONFIG_AUDIT */

diff --git a/kernel/audit.c b/kernel/audit.c
index fc9f026f..c5fed3b 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -100,9 +100,13 @@
/**
* struct audit_net - audit private network namespace data
* @sk: communication socket
+ * @contid_list: audit container identifier list
+ * @contid_list_lock audit container identifier list lock
*/
struct audit_net {
struct sock *sk;
+ struct list_head contid_list;
+ spinlock_t contid_list_lock;
};

/**
@@ -308,6 +312,86 @@ static struct sock *audit_get_sk(const struct net *net)
return aunet->sk;
}

+/**
+ * audit_get_netns_contid_list - Return the audit container ID list for the given network namespace
+ * @net: the destination network namespace
+ *
+ * Description:
+ * Returns the list pointer if valid, NULL otherwise. The caller must ensure
+ * that a reference is held for the network namespace while the sock is in use.
+ */
+struct list_head *audit_get_netns_contid_list(const struct net *net)
+{
+ struct audit_net *aunet = net_generic(net, audit_net_id);
+
+ return &aunet->contid_list;
+}
+
+spinlock_t *audit_get_netns_contid_list_lock(const struct net *net)
+{
+ struct audit_net *aunet = net_generic(net, audit_net_id);
+
+ return &aunet->contid_list_lock;
+}
+
+void audit_netns_contid_add(struct net *net, u64 contid)
+{
+ spinlock_t *lock = audit_get_netns_contid_list_lock(net);
+ struct list_head *contid_list = audit_get_netns_contid_list(net);
+ struct audit_contid *cont;
+
+ if (!audit_contid_valid(contid))
+ return;
+ spin_lock(lock);
+ if (!list_empty(contid_list))
+ list_for_each_entry(cont, contid_list, list)
+ if (cont->id == contid) {
+ refcount_inc(&cont->refcount);
+ goto out;
+ }
+ cont = kmalloc(sizeof(struct audit_contid), GFP_KERNEL);
+ if (cont) {
+ INIT_LIST_HEAD(&cont->list);
+ cont->id = contid;
+ refcount_set(&cont->refcount, 1);
+ list_add(&cont->list, contid_list);
+ }
+out:
+ spin_unlock(lock);
+}
+
+void audit_netns_contid_del(struct net *net, u64 contid)
+{
+ spinlock_t *lock = audit_get_netns_contid_list_lock(net);
+ struct list_head *contid_list = audit_get_netns_contid_list(net);
+ struct audit_contid *cont = NULL;
+
+ if (!audit_contid_valid(contid))
+ return;
+ spin_lock(lock);
+ if (!list_empty(contid_list))
+ list_for_each_entry(cont, contid_list, list)
+ if (cont->id == contid) {
+ list_del(&cont->list);
+ if (refcount_dec_and_test(&cont->refcount))
+ kfree(cont);
+ break;
+ }
+ spin_unlock(lock);
+}
+
+void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p)
+{
+ u64 contid = audit_get_contid(p);
+ struct nsproxy *new = p->nsproxy;
+
+ if (!audit_contid_valid(contid))
+ return;
+ audit_netns_contid_del(ns->net_ns, contid);
+ if (new)
+ audit_netns_contid_add(new->net_ns, contid);
+}
+
void audit_panic(const char *message)
{
switch (audit_failure) {
@@ -1547,6 +1631,8 @@ static int __net_init audit_net_init(struct net *net)
return -ENOMEM;
}
aunet->sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
+ INIT_LIST_HEAD(&aunet->contid_list);
+ spin_lock_init(&aunet->contid_list_lock);

return 0;
}
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 610c6869..fdf3f68 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -75,6 +75,7 @@
#include <linux/uaccess.h>
#include <linux/fsnotify_backend.h>
#include <uapi/linux/limits.h>
+#include <net/net_namespace.h>

#include "audit.h"

@@ -2165,6 +2166,7 @@ int audit_set_contid(struct task_struct *task, u64 contid)
uid_t uid;
struct tty_struct *tty;
char comm[sizeof(current->comm)];
+ struct net *net = task->nsproxy->net_ns;

task_lock(task);
/* Can't set if audit disabled */
@@ -2186,8 +2188,12 @@ int audit_set_contid(struct task_struct *task, u64 contid)
else if (!(thread_group_leader(task) && thread_group_empty(task)))
rc = -EALREADY;
read_unlock(&tasklist_lock);
- if (!rc)
+ if (!rc) {
+ if (audit_contid_valid(oldcontid))
+ audit_netns_contid_del(net, oldcontid);
task->audit->contid = contid;
+ audit_netns_contid_add(net, contid);
+ }
task_unlock(task);

if (!audit_enabled)
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index f6c5d33..718b120 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -27,6 +27,7 @@
#include <linux/syscalls.h>
#include <linux/cgroup.h>
#include <linux/perf_event.h>
+#include <linux/audit.h>

static struct kmem_cache *nsproxy_cachep;

@@ -140,6 +141,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
struct nsproxy *old_ns = tsk->nsproxy;
struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
struct nsproxy *new_ns;
+ u64 contid = audit_get_contid(tsk);

if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
CLONE_NEWPID | CLONE_NEWNET |
@@ -167,6 +169,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
return PTR_ERR(new_ns);

tsk->nsproxy = new_ns;
+ audit_netns_contid_add(new_ns->net_ns, contid);
return 0;
}

@@ -224,6 +227,7 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
ns = p->nsproxy;
p->nsproxy = new;
task_unlock(p);
+ audit_switch_task_namespaces(ns, p);

if (ns && atomic_dec_and_test(&ns->count))
free_nsproxy(ns);
--
1.8.3.1