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 <[email protected]> --- include/linux/audit.h | 14 ++++++-- kernel/audit.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++--- kernel/audit.h | 8 +++++ 3 files changed, 112 insertions(+), 8 deletions(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index a045b34ecf44..0e6dbe943ae4 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -94,10 +94,18 @@ struct audit_ntp_data { struct audit_ntp_data {}; #endif +struct audit_contobj { + 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_contobj *cont; #ifdef CONFIG_AUDITSYSCALL struct audit_context *ctx; #endif @@ -203,9 +211,9 @@ 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 u32 audit_enabled; diff --git a/kernel/audit.c b/kernel/audit.c index 2d7707426b7d..4bab20f5f781 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -138,6 +138,12 @@ struct auditd_connection { /* Hash for inode-based rules */ struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; +/* Hash for contid object lists */ +struct list_head audit_contid_hash[AUDIT_CONTID_BUCKETS]; +/* Lock all additions and deletions to the contid hash lists, assignment + * of container objects to tasks and refcount changes. There should be + * no need for interaction with tasklist_lock */ +static DEFINE_SPINLOCK(audit_contobj_list_lock); static struct kmem_cache *audit_buffer_cache; @@ -212,6 +218,31 @@ void __init audit_task_init(void) 0, SLAB_PANIC, NULL); } +static struct audit_contobj *_audit_contobj(struct task_struct *tsk) +{ + if (!tsk->audit) + return NULL; + return tsk->audit->cont; +} + +/* audit_contobj_list_lock must be held by caller unless new */ +static void _audit_contobj_hold(struct audit_contobj *cont) +{ + refcount_inc(&cont->refcount); +} + +/* audit_contobj_list_lock must be held by caller */ +static void _audit_contobj_put(struct audit_contobj *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); + } +} + /** * audit_alloc - allocate an audit info block for a task * @tsk: task @@ -232,7 +263,11 @@ 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); + spin_lock(&audit_contobj_list_lock); + info->cont = _audit_contobj(current); + if (info->cont) + _audit_contobj_hold(info->cont); + spin_unlock(&audit_contobj_list_lock); tsk->audit = info; ret = audit_alloc_syscall(tsk); @@ -247,7 +282,7 @@ 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 @@ -267,6 +302,9 @@ 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_contobj_list_lock); + _audit_contobj_put(tsk->audit->cont); + spin_unlock(&audit_contobj_list_lock); info = tsk->audit; tsk->audit = NULL; kmem_cache_free(audit_task_cache, info); @@ -1658,6 +1696,9 @@ 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; @@ -2365,6 +2406,9 @@ int audit_signal_info(int sig, struct task_struct *t) * * Returns 0 on success, -EPERM on permission failure. * + * If the original container owner goes away, no task injection is + * possible to an existing container. + * * Called (set) from fs/proc/base.c::proc_contid_write(). */ int audit_set_contid(struct task_struct *task, u64 contid) @@ -2381,9 +2425,12 @@ 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; @@ -2396,8 +2443,49 @@ 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_contobj *oldcont = _audit_contobj(task); + struct audit_contobj *cont = NULL, *newcont = NULL; + int h = audit_hash_contid(contid); + + rcu_read_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) { + spin_lock(&audit_contobj_list_lock); + _audit_contobj_hold(cont); + spin_unlock(&audit_contobj_list_lock); + newcont = cont; + } else { + rc = -ENOTUNIQ; + goto conterror; + } + break; + } + if (!newcont) { + newcont = kmalloc(sizeof(*newcont), GFP_ATOMIC); + if (newcont) { + INIT_LIST_HEAD(&newcont->list); + newcont->id = contid; + get_task_struct(current); + newcont->owner = current; + refcount_set(&newcont->refcount, 1); + spin_lock(&audit_contobj_list_lock); + list_add_rcu(&newcont->list, &audit_contid_hash[h]); + spin_unlock(&audit_contobj_list_lock); + } else { + rc = -ENOMEM; + goto conterror; + } + } + task->audit->cont = newcont; + spin_lock(&audit_contobj_list_lock); + _audit_contobj_put(oldcont); + spin_unlock(&audit_contobj_list_lock); +conterror: + rcu_read_unlock(); + } 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 -- Linux-audit mailing list [email protected] https://www.redhat.com/mailman/listinfo/linux-audit
