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Subject[PATCH ghak90 V7 04/21] audit: convert to contid list to check for orch/engine ownership
Date
Store the audit container identifier in a refcounted kernel object that
is added to the master list of audit container identifiers. This will
allow multiple container orchestrators/engines to work on the same
machine without danger of inadvertantly re-using an existing identifier.
It will also allow an orchestrator to inject a process into an existing
container by checking if the original container owner is the one
injecting the task. A hash table list is used to optimize searches.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
include/linux/audit.h | 26 ++++++++++++++--
kernel/audit.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++---
kernel/audit.h | 8 +++++
3 files changed, 112 insertions(+), 8 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index f2e3b81f2942..e317807cdd3e 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -95,10 +95,18 @@ struct audit_ntp_data {
struct audit_ntp_data {};
#endif

+struct audit_cont {
+ struct list_head list;
+ u64 id;
+ struct task_struct *owner;
+ refcount_t refcount;
+ struct rcu_head rcu;
+};
+
struct audit_task_info {
kuid_t loginuid;
unsigned int sessionid;
- u64 contid;
+ struct audit_cont *cont;
#ifdef CONFIG_AUDITSYSCALL
struct audit_context *ctx;
#endif
@@ -203,11 +211,15 @@ static inline unsigned int audit_get_sessionid(struct task_struct *tsk)

static inline u64 audit_get_contid(struct task_struct *tsk)
{
- if (!tsk->audit)
+ if (!tsk->audit || !tsk->audit->cont)
return AUDIT_CID_UNSET;
- return tsk->audit->contid;
+ return tsk->audit->cont->id;
}

+extern struct audit_cont *audit_cont(struct task_struct *tsk);
+
+extern void audit_cont_put(struct audit_cont *cont);
+
extern u32 audit_enabled;

extern int audit_signal_info(int sig, struct task_struct *t);
@@ -277,6 +289,14 @@ static inline u64 audit_get_contid(struct task_struct *tsk)
return AUDIT_CID_UNSET;
}

+static inline struct audit_cont *audit_cont(struct task_struct *tsk)
+{
+ return NULL;
+}
+
+static inline void audit_cont_put(struct audit_cont *cont)
+{ }
+
#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 a36ea57cbb61..ea0899130cc1 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -137,6 +137,8 @@ struct audit_net {

/* Hash for inode-based rules */
struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
+/* Hash for contid-based rules */
+struct list_head audit_contid_hash[AUDIT_CONTID_BUCKETS];

static struct kmem_cache *audit_buffer_cache;

@@ -204,6 +206,8 @@ struct audit_reply {

static struct kmem_cache *audit_task_cache;

+static DEFINE_SPINLOCK(audit_contid_list_lock);
+
void __init audit_task_init(void)
{
audit_task_cache = kmem_cache_create("audit_task",
@@ -231,7 +235,9 @@ int audit_alloc(struct task_struct *tsk)
}
info->loginuid = audit_get_loginuid(current);
info->sessionid = audit_get_sessionid(current);
- info->contid = audit_get_contid(current);
+ info->cont = audit_cont(current);
+ if (info->cont)
+ refcount_inc(&info->cont->refcount);
tsk->audit = info;

ret = audit_alloc_syscall(tsk);
@@ -246,7 +252,7 @@ int audit_alloc(struct task_struct *tsk)
struct audit_task_info init_struct_audit = {
.loginuid = INVALID_UID,
.sessionid = AUDIT_SID_UNSET,
- .contid = AUDIT_CID_UNSET,
+ .cont = NULL,
#ifdef CONFIG_AUDITSYSCALL
.ctx = NULL,
#endif
@@ -266,6 +272,9 @@ void audit_free(struct task_struct *tsk)
/* Freeing the audit_task_info struct must be performed after
* audit_log_exit() due to need for loginuid and sessionid.
*/
+ spin_lock(&audit_contid_list_lock);
+ audit_cont_put(tsk->audit->cont);
+ spin_unlock(&audit_contid_list_lock);
info = tsk->audit;
tsk->audit = NULL;
kmem_cache_free(audit_task_cache, info);
@@ -1657,6 +1666,9 @@ static int __init audit_init(void)
for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
INIT_LIST_HEAD(&audit_inode_hash[i]);

+ for (i = 0; i < AUDIT_CONTID_BUCKETS; i++)
+ INIT_LIST_HEAD(&audit_contid_hash[i]);
+
mutex_init(&audit_cmd_mutex.lock);
audit_cmd_mutex.owner = NULL;

@@ -2356,6 +2368,32 @@ int audit_signal_info(int sig, struct task_struct *t)
return audit_signal_info_syscall(t);
}

+struct audit_cont *audit_cont(struct task_struct *tsk)
+{
+ if (!tsk->audit || !tsk->audit->cont)
+ return NULL;
+ return tsk->audit->cont;
+}
+
+/* audit_contid_list_lock must be held by caller */
+void audit_cont_put(struct audit_cont *cont)
+{
+ if (!cont)
+ return;
+ if (refcount_dec_and_test(&cont->refcount)) {
+ put_task_struct(cont->owner);
+ list_del_rcu(&cont->list);
+ kfree_rcu(cont, rcu);
+ }
+}
+
+static struct task_struct *audit_cont_owner(struct task_struct *tsk)
+{
+ if (tsk->audit && tsk->audit->cont)
+ return tsk->audit->cont->owner;
+ return NULL;
+}
+
/*
* audit_set_contid - set current task's audit contid
* @task: target task
@@ -2382,9 +2420,12 @@ int audit_set_contid(struct task_struct *task, u64 contid)
}
oldcontid = audit_get_contid(task);
read_lock(&tasklist_lock);
- /* Don't allow the audit containerid to be unset */
+ /* Don't allow the contid to be unset */
if (!audit_contid_valid(contid))
rc = -EINVAL;
+ /* Don't allow the contid to be set to the same value again */
+ else if (contid == oldcontid) {
+ rc = -EADDRINUSE;
/* if we don't have caps, reject */
else if (!capable(CAP_AUDIT_CONTROL))
rc = -EPERM;
@@ -2397,8 +2438,43 @@ int audit_set_contid(struct task_struct *task, u64 contid)
else if (audit_contid_set(task))
rc = -ECHILD;
read_unlock(&tasklist_lock);
- if (!rc)
- task->audit->contid = contid;
+ if (!rc) {
+ struct audit_cont *oldcont = audit_cont(task);
+ struct audit_cont *cont = NULL;
+ struct audit_cont *newcont = NULL;
+ int h = audit_hash_contid(contid);
+
+ spin_lock(&audit_contid_list_lock);
+ list_for_each_entry_rcu(cont, &audit_contid_hash[h], list)
+ if (cont->id == contid) {
+ /* task injection to existing container */
+ if (current == cont->owner) {
+ refcount_inc(&cont->refcount);
+ newcont = cont;
+ } else {
+ rc = -ENOTUNIQ;
+ goto conterror;
+ }
+ }
+ if (!newcont) {
+ newcont = kmalloc(sizeof(struct audit_cont), GFP_ATOMIC);
+ if (newcont) {
+ INIT_LIST_HEAD(&newcont->list);
+ newcont->id = contid;
+ get_task_struct(current);
+ newcont->owner = current;
+ refcount_set(&newcont->refcount, 1);
+ list_add_rcu(&newcont->list, &audit_contid_hash[h]);
+ } else {
+ rc = -ENOMEM;
+ goto conterror;
+ }
+ }
+ task->audit->cont = newcont;
+ audit_cont_put(oldcont);
+conterror:
+ spin_unlock(&audit_contid_list_lock);
+ }
task_unlock(task);

if (!audit_enabled)
diff --git a/kernel/audit.h b/kernel/audit.h
index 16bd03b88e0d..e4a31aa92dfe 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -211,6 +211,14 @@ static inline int audit_hash_ino(u32 ino)
return (ino & (AUDIT_INODE_BUCKETS-1));
}

+#define AUDIT_CONTID_BUCKETS 32
+extern struct list_head audit_contid_hash[AUDIT_CONTID_BUCKETS];
+
+static inline int audit_hash_contid(u64 contid)
+{
+ return (contid & (AUDIT_CONTID_BUCKETS-1));
+}
+
/* Indicates that audit should log the full pathname. */
#define AUDIT_NAME_FULL -1

--
1.8.3.1
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