[PATCH ghak90 v10 08/11] audit: add support for containerid to network namespaces

From: Richard Guy Briggs
Date: Mon Dec 21 2020 - 12:00:02 EST

This also adds support to qualify NETFILTER_PKT records.

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

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.

Sample event:
type=NETFILTER_PKT msg=audit(2020-11-26 10:24:47.984:174549) : mark=0x15766399 saddr=127.0.0.1 daddr=127.0.0.1 proto=icmp record=1
type=CONTAINER_ID msg=audit(2020-11-26 10:24:47.984:174549) : record=1 contid=4112973747854606336,1916436506412318720

Please see the github audit kernel issue for contid net support:
https://github.com/linux-audit/audit-kernel/issues/92
Please see the github audit testsuiite issue for the test case:
https://github.com/linux-audit/audit-testsuite/issues/64
Please see the github audit wiki for the feature overview:
https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID
Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Reviewed-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
---
include/linux/audit.h | 17 +++
kernel/audit.c | 229 ++++++++++++++++++++++++++++++++++-----
kernel/nsproxy.c | 4 +
net/netfilter/nft_log.c | 14 ++-
net/netfilter/xt_AUDIT.c | 14 ++-
5 files changed, 249 insertions(+), 29 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 056a7c9a12a2..014f73296fec 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -217,6 +217,12 @@ extern int audit_get_contid_proc(char *tmpbuf, int TMPBUFLEN,

extern int audit_set_contid(struct task_struct *tsk, u64 contid);

+extern void audit_copy_namespaces(struct net *net, struct task_struct *tsk);
+extern void audit_switch_task_namespaces(struct nsproxy *ns,
+ struct task_struct *p);
+extern int audit_log_netns_contid_list(struct net *net,
+ struct audit_context *context);
+
extern u32 audit_enabled;

extern int audit_signal_info(int sig, struct task_struct *t);
@@ -281,6 +287,17 @@ static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
return AUDIT_SID_UNSET;
}

+static inline void audit_copy_namespaces(struct net *net, struct task_struct *tsk)
+{ }
+static inline void audit_switch_task_namespaces(struct nsproxy *ns,
+ struct task_struct *p)
+{ }
+static inline int audit_log_netns_contid_list(struct net *net,
+ struct audit_context *context)
+{
+ return 0;
+}
+
#define audit_enabled AUDIT_OFF

static inline int audit_signal_info(int sig, struct task_struct *t)
diff --git a/kernel/audit.c b/kernel/audit.c
index 300daf2bcb16..8d03f07e7128 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -59,6 +59,7 @@
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
#include <net/netns/generic.h>
+#include <net/net_namespace.h>

#include "audit.h"

@@ -86,9 +87,13 @@ static unsigned int audit_net_id;
/**
* struct audit_net - audit private network namespace data
* @sk: communication socket
+ * @contobj_list: audit container identifier list
+ * @contobj_list_lock audit container identifier list lock
*/
struct audit_net {
struct sock *sk;
+ struct list_head contobj_list;
+ spinlock_t contobj_list_lock;
};

/**
@@ -239,6 +244,16 @@ struct audit_task_info {

static struct kmem_cache *audit_task_cache;

+struct audit_contobj_netns {
+ struct list_head list;
+ struct audit_contobj *obj;
+ int count;
+ struct rcu_head rcu;
+};
+
+static void audit_netns_contid_add(struct net *net, struct audit_contobj *cont);
+static void audit_netns_contid_del(struct net *net, struct audit_contobj *cont);
+
void __init audit_task_init(void)
{
audit_task_cache = kmem_cache_create("audit_task",
@@ -372,11 +387,12 @@ void audit_contobj_put(void **cont, int count)
{
int i;
struct audit_contobj **contobj = (struct audit_contobj **)cont;
+ unsigned long flags;

- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
for (i = 0; i < count; i++)
_audit_contobj_put(contobj[i]);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
}

static inline int audit_hash_contid(u64 contid)
@@ -452,11 +468,24 @@ int audit_alloc(struct task_struct *tsk)
void audit_free(struct task_struct *tsk)
{
struct audit_task_info *info = tsk->audit;
+ unsigned long flags;
+ struct nsproxy *ns = tsk->nsproxy;
+ struct audit_contobj *cont;

+ rcu_read_lock();
+ cont = _audit_contobj_get_bytask(tsk);
+ rcu_read_unlock();
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
+ if (ns) {
+ audit_netns_contid_del(ns->net_ns, cont);
+ _audit_contobj_put(cont);
+ }
+ _audit_contobj_put(cont);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
audit_free_syscall(tsk);
- spin_lock(&_audit_contobj_list_lock);
- _audit_contobj_put(info->cont);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
+ _audit_contobj_put(cont);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
/* Freeing the audit_task_info struct must be performed after
* audit_log_exit() due to need for loginuid and sessionid.
*/
@@ -464,9 +493,9 @@ void audit_free(struct task_struct *tsk)
kmem_cache_free(audit_task_cache, info);
rcu_read_lock();
if (audit_sig_adtsk == tsk) {
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put_sig(audit_sig_cid);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
audit_sig_cid = NULL;
audit_sig_adtsk = NULL;
}
@@ -564,6 +593,145 @@ static struct sock *audit_get_sk(const struct net *net)
return aunet->sk;
}

+void audit_netns_contid_add(struct net *net, struct audit_contobj *cont)
+{
+ struct audit_net *aunet;
+ struct list_head *contobj_list;
+ struct audit_contobj_netns *contns;
+
+ if (!net)
+ return;
+ if (!cont)
+ return;
+ aunet = net_generic(net, audit_net_id);
+ if (!aunet)
+ return;
+ contobj_list = &aunet->contobj_list;
+ rcu_read_lock();
+ spin_lock(&aunet->contobj_list_lock);
+ list_for_each_entry_rcu(contns, contobj_list, list)
+ if (contns->obj == cont) {
+ contns->count++;
+ goto out;
+ }
+ contns = kmalloc(sizeof(*contns), GFP_ATOMIC);
+ if (contns) {
+ INIT_LIST_HEAD(&contns->list);
+ contns->obj = cont;
+ contns->count = 1;
+ list_add_rcu(&contns->list, contobj_list);
+ }
+out:
+ spin_unlock(&aunet->contobj_list_lock);
+ rcu_read_unlock();
+}
+
+void audit_netns_contid_del(struct net *net, struct audit_contobj *cont)
+{
+ struct audit_net *aunet;
+ struct list_head *contobj_list;
+ struct audit_contobj_netns *contns = NULL;
+
+ if (!net)
+ return;
+ if (!cont)
+ return;
+ aunet = net_generic(net, audit_net_id);
+ if (!aunet)
+ return;
+ contobj_list = &aunet->contobj_list;
+ rcu_read_lock();
+ spin_lock(&aunet->contobj_list_lock);
+ list_for_each_entry_rcu(contns, contobj_list, list)
+ if (contns->obj == cont) {
+ contns->count--;
+ if (contns->count < 1) {
+ list_del_rcu(&contns->list);
+ kfree_rcu(contns, rcu);
+ }
+ break;
+ }
+ spin_unlock(&aunet->contobj_list_lock);
+ rcu_read_unlock();
+}
+
+void audit_copy_namespaces(struct net *net, struct task_struct *tsk)
+{
+ struct audit_contobj *cont;
+
+ rcu_read_lock();
+ cont = _audit_contobj_get_bytask(tsk);
+ rcu_read_unlock();
+ audit_netns_contid_add(net, cont);
+}
+
+void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p)
+{
+ struct audit_contobj *cont;
+ struct nsproxy *new = p->nsproxy;
+ unsigned long flags;
+
+ rcu_read_lock();
+ cont = _audit_contobj_get_bytask(p);
+ rcu_read_unlock();
+ if (!cont)
+ return;
+ audit_netns_contid_del(ns->net_ns, cont);
+ if (new)
+ audit_netns_contid_add(new->net_ns, cont);
+ else {
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
+ _audit_contobj_put(cont);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
+ }
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
+ _audit_contobj_put(cont);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
+}
+
+/**
+ * audit_log_netns_contid_list - List contids for the given network namespace
+ * @net: the network namespace of interest
+ * @context: the audit context to use
+ *
+ * Returns 1 for record, 0 for none.
+ *
+ * Description:
+ * Issues a CONTAINER_ID record with a CSV list of contids associated
+ * with a network namespace to accompany a NETFILTER_PKT record.
+ */
+int audit_log_netns_contid_list(struct net *net, struct audit_context *context)
+{
+ struct audit_buffer *ab = NULL;
+ struct audit_contobj_netns *cont;
+ struct audit_net *aunet = net_generic(net, audit_net_id);
+ unsigned int record;
+
+ if (!aunet)
+ return 0;
+ rcu_read_lock();
+ list_for_each_entry_rcu(cont, &aunet->contobj_list, list) {
+ record = 1;
+ if (!ab) {
+ ab = audit_log_start(context, GFP_ATOMIC,
+ AUDIT_CONTAINER_ID);
+ if (!ab) {
+ audit_log_lost("out of memory in audit_log_netns_contid_list");
+ goto out;
+ }
+ audit_log_format(ab, "record=1 contid=%llu",
+ cont->obj->id);
+ } else {
+ audit_log_format(ab, ",%llu", cont->obj->id);
+ }
+ }
+ audit_log_end(ab);
+out:
+ rcu_read_unlock();
+ return record;
+}
+EXPORT_SYMBOL(audit_log_netns_contid_list);
+
void audit_panic(const char *message)
{
switch (audit_failure) {
@@ -1453,6 +1621,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
struct audit_sig_info2 *sig_data2;
char *ctx = NULL;
u32 len;
+ unsigned long flags;

err = audit_netlink_ok(skb, msg_type);
if (err)
@@ -1726,9 +1895,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
sig_data, sizeof(*sig_data) + len);
kfree(sig_data);
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put_sig(audit_sig_cid);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
audit_sig_cid = NULL;
break;
case AUDIT_SIGNAL_INFO2: {
@@ -1769,9 +1938,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
memcpy(sig_data2->data + contidstrlen, ctx, len);
security_release_secctx(ctx, len);
}
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put_sig(audit_sig_cid);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
audit_sig_cid = NULL;
audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO2, 0, 0,
sig_data2, sizeof(*sig_data2) + contidstrlen + len);
@@ -1926,7 +2095,8 @@ static int __net_init audit_net_init(struct net *net)
return -ENOMEM;
}
aunet->sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
-
+ INIT_LIST_HEAD(&aunet->contobj_list);
+ spin_lock_init(&aunet->contobj_list_lock);
return 0;
}

@@ -2475,6 +2645,7 @@ int audit_log_container_id_ctx(struct audit_context *context)
{
struct audit_contobj *contobj;
int record;
+ unsigned long flags;

rcu_read_lock();
contobj = _audit_contobj_get_bytask(current);
@@ -2482,9 +2653,9 @@ int audit_log_container_id_ctx(struct audit_context *context)
if (!contobj)
return 0;
record = _audit_log_container_id(context, contobj);
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put(contobj);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
return record;
}

@@ -2731,6 +2902,7 @@ int audit_signal_info(int sig, struct task_struct *t)
(sig == SIGTERM || sig == SIGHUP ||
sig == SIGUSR1 || sig == SIGUSR2)) {
kuid_t uid = current_uid(), auid;
+ unsigned long flags;

audit_sig_pid = task_tgid_nr(current);
auid = audit_get_loginuid(current);
@@ -2739,9 +2911,9 @@ int audit_signal_info(int sig, struct task_struct *t)
else
audit_sig_uid = uid;
security_task_getsecid(current, &audit_sig_sid);
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put_sig(audit_sig_cid);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
rcu_read_lock();
audit_sig_cid = _audit_contobj_get_sig_bytask(current);
rcu_read_unlock();
@@ -2771,6 +2943,8 @@ int audit_set_contid(struct task_struct *tsk, u64 contid)
struct audit_contobj *cont = NULL, *newcont = NULL;
int h;
struct audit_task_info *info = tsk->audit;
+ unsigned long flags;
+ struct net *net = tsk->nsproxy->net_ns;

/* Can't set if audit disabled */
if (!info) {
@@ -2799,21 +2973,21 @@ int audit_set_contid(struct task_struct *tsk, u64 contid)
goto error;

h = audit_hash_contid(contid);
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
list_for_each_entry_rcu(cont, &audit_contid_hash[h], list)
if (cont->id == contid) {
/* task injection to existing container */
if (current == cont->owner) {
if (!refcount_read(&cont->refcount)) {
rc = -ENOTUNIQ;
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
goto error;
}
_audit_contobj_get(cont);
newcont = cont;
} else {
rc = -ENOTUNIQ;
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
goto error;
}
break;
@@ -2829,13 +3003,17 @@ int audit_set_contid(struct task_struct *tsk, u64 contid)
&audit_contid_hash[h]);
} else {
rc = -ENOMEM;
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
goto error;
}
}
info->cont = newcont;
_audit_contobj_put(oldcont);
- spin_unlock(&_audit_contobj_list_lock);
+ audit_netns_contid_del(net, oldcont);
+ _audit_contobj_put(oldcont);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
+ _audit_contobj_get(newcont);
+ audit_netns_contid_add(net, newcont);
error:
rcu_read_unlock();
task_unlock(tsk);
@@ -2851,9 +3029,9 @@ int audit_set_contid(struct task_struct *tsk, u64 contid)
audit_log_format(ab,
"op=set opid=%d contid=%llu old-contid=%llu",
task_tgid_nr(tsk), contid, oldcont ? oldcont->id : -1);
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put(oldcont);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
audit_log_end(ab);
return rc;
}
@@ -2877,6 +3055,7 @@ void audit_log_container_drop(void)
{
struct audit_buffer *ab;
struct audit_contobj *cont;
+ unsigned long flags;

rcu_read_lock();
cont = _audit_contobj_get_bytask(current);
@@ -2892,9 +3071,9 @@ void audit_log_container_drop(void)
task_tgid_nr(current), cont->id);
audit_log_end(ab);
out:
- spin_lock(&_audit_contobj_list_lock);
+ spin_lock_irqsave(&_audit_contobj_list_lock, flags);
_audit_contobj_put(cont);
- spin_unlock(&_audit_contobj_list_lock);
+ spin_unlock_irqrestore(&_audit_contobj_list_lock, flags);
}

/**
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 12dd41b39a7f..e5ac1f37efd3 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -26,6 +26,7 @@
#include <linux/syscalls.h>
#include <linux/cgroup.h>
#include <linux/perf_event.h>
+#include <linux/audit.h>

static struct kmem_cache *nsproxy_cachep;

@@ -187,6 +188,8 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
}

tsk->nsproxy = new_ns;
+ if (flags & CLONE_NEWNET)
+ audit_copy_namespaces(new_ns->net_ns, tsk);
return 0;
}

@@ -249,6 +252,7 @@ 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);
diff --git a/net/netfilter/nft_log.c b/net/netfilter/nft_log.c
index 57899454a530..383becc41889 100644
--- a/net/netfilter/nft_log.c
+++ b/net/netfilter/nft_log.c
@@ -66,13 +66,19 @@ static void nft_log_eval_audit(const struct nft_pktinfo *pkt)
struct sk_buff *skb = pkt->skb;
struct audit_buffer *ab;
int fam = -1;
+ struct audit_context *context;
+ struct net *net;
+ int record;

if (!audit_enabled)
return;

- ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
+ context = audit_alloc_local(GFP_ATOMIC);
+ net = xt_net(&pkt->xt);
+ record = audit_log_netns_contid_list(net, context);
+ ab = audit_log_start(context, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
if (!ab)
- return;
+ goto errout;

audit_log_format(ab, "mark=%#x", skb->mark);

@@ -98,7 +104,11 @@ static void nft_log_eval_audit(const struct nft_pktinfo *pkt)
if (fam == -1)
audit_log_format(ab, " saddr=? daddr=? proto=-1");

+ if (record)
+ audit_log_format(ab, " record=%d", record);
audit_log_end(ab);
+errout:
+ audit_free_context(context);
}

static void nft_log_eval(const struct nft_expr *expr,
diff --git a/net/netfilter/xt_AUDIT.c b/net/netfilter/xt_AUDIT.c
index 9cdc16b0d0d8..d2c5069745ea 100644
--- a/net/netfilter/xt_AUDIT.c
+++ b/net/netfilter/xt_AUDIT.c
@@ -68,10 +68,16 @@ audit_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
struct audit_buffer *ab;
int fam = -1;
+ struct audit_context *context;
+ struct net *net;
+ int record;

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);
+ net = xt_net(par);
+ record = audit_log_netns_contid_list(net, context);
+ ab = audit_log_start(context, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
if (ab == NULL)
goto errout;

@@ -99,9 +105,13 @@ audit_tg(struct sk_buff *skb, const struct xt_action_param *par)
if (fam == -1)
audit_log_format(ab, " saddr=? daddr=? proto=-1");

+ if (record)
+ audit_log_format(ab, " record=%d", record);
audit_log_end(ab);

errout:
+ audit_free_context(context);
+out:
return XT_CONTINUE;
}

--
2.18.4