Re: [PATCH ghak90 V7 04/21] audit: convert to contid list to check for orch/engine ownership

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(a)redhat.com&gt; --- 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