Re: [PATCH ghak90 V9 01/13] audit: collect audit task parameters

The audit-related parameters in struct task_struct should ideally be collected together and accessed through a standard audit API. Collect the existing loginuid, sessionid and audit_context together in a new struct audit_task_info called "audit" in struct task_struct. Use kmem_cache to manage this pool of memory. Un-inline audit_free() to be able to always recover that memory. Please see the upstream github issue https://github.com/linux-audit/audit-kernel/issues/81 Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; Acked-by: Neil Horman <nhorman(a)tuxdriver.com&gt; Reviewed-by: Ondrej Mosnacek <omosnace(a)redhat.com&gt; --- include/linux/audit.h | 49 +++++++++++++++++++++++------------ include/linux/sched.h | 7 +---- init/init_task.c | 3 +-- init/main.c | 2 ++ kernel/audit.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++-- kernel/audit.h | 5 ++++ kernel/auditsc.c | 26 ++++++++++--------- kernel/fork.c | 1 - 8 files changed, 124 insertions(+), 40 deletions(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index 3fcd9ee49734..c2150415f9df 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -100,6 +100,16 @@ enum audit_nfcfgop { AUDIT_XT_OP_UNREGISTER, }; +struct audit_task_info { + kuid_t loginuid; + unsigned int sessionid; +#ifdef CONFIG_AUDITSYSCALL + struct audit_context *ctx; +#endif +}; + +extern struct audit_task_info init_struct_audit; + extern int is_audit_feature_set(int which); extern int __init audit_register_class(int class, unsigned *list);

diff --git a/include/linux/sched.h b/include/linux/sched.h index b62e6aaf28f0..2213ac670386 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -34,7 +34,6 @@ #include <linux/kcsan.h> /* task_struct member predeclarations (sorted alphabetically): */ -struct audit_context; struct backing_dev_info; struct bio_list; struct blk_plug; @@ -946,11 +945,7 @@ struct task_struct { struct callback_head *task_works; #ifdef CONFIG_AUDIT -#ifdef CONFIG_AUDITSYSCALL - struct audit_context *audit_context; -#endif - kuid_t loginuid; - unsigned int sessionid; + struct audit_task_info *audit; #endif struct seccomp seccomp;

diff --git a/init/init_task.c b/init/init_task.c index 15089d15010a..92d34c4b7702 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -130,8 +130,7 @@ struct task_struct init_task .thread_group = LIST_HEAD_INIT(init_task.thread_group), .thread_node = LIST_HEAD_INIT(init_signals.thread_head), #ifdef CONFIG_AUDIT - .loginuid = INVALID_UID, - .sessionid = AUDIT_SID_UNSET, + .audit = &init_struct_audit, #endif #ifdef CONFIG_PERF_EVENTS .perf_event_mutex = __MUTEX_INITIALIZER(init_task.perf_event_mutex), diff --git a/init/main.c b/init/main.c index 0ead83e86b5a..349470ad7458 100644 --- a/init/main.c +++ b/init/main.c @@ -96,6 +96,7 @@ #include <linux/jump_label.h> #include <linux/mem_encrypt.h> #include <linux/kcsan.h> +#include <linux/audit.h> #include <asm/io.h> #include <asm/bugs.h> @@ -1028,6 +1029,7 @@ asmlinkage __visible void __init start_kernel(void) nsfs_init(); cpuset_init(); cgroup_init(); + audit_task_init(); taskstats_init_early(); delayacct_init(); diff --git a/kernel/audit.c b/kernel/audit.c index 8c201f414226..5d8147a29291 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -203,6 +203,73 @@ struct audit_reply { struct sk_buff *skb; }; +static struct kmem_cache *audit_task_cache; + +void __init audit_task_init(void) +{ + audit_task_cache = kmem_cache_create("audit_task", + sizeof(struct audit_task_info), + 0, SLAB_PANIC, NULL); +} + +/** + * audit_alloc - allocate an audit info block for a task + * @tsk: task + * + * Call audit_alloc_syscall to filter on the task information and + * allocate a per-task audit context if necessary. This is called from + * copy_process, so no lock is needed. + */ +int audit_alloc(struct task_struct *tsk) +{ + int ret = 0; + struct audit_task_info *info; + + info = kmem_cache_alloc(audit_task_cache, GFP_KERNEL); + if (!info) { + ret = -ENOMEM; + goto out; + } + info->loginuid = audit_get_loginuid(current); + info->sessionid = audit_get_sessionid(current); + tsk->audit = info; + + ret = audit_alloc_syscall(tsk); + if (ret) { + tsk->audit = NULL; + kmem_cache_free(audit_task_cache, info); + } +out: + return ret; +}

+struct audit_task_info init_struct_audit = { + .loginuid = INVALID_UID, + .sessionid = AUDIT_SID_UNSET, +#ifdef CONFIG_AUDITSYSCALL + .ctx = NULL, +#endif +}; + +/** + * audit_free - free per-task audit info + * @tsk: task whose audit info block to free + * + * Called from copy_process and do_exit + */ +void audit_free(struct task_struct *tsk) +{ + struct audit_task_info *info = tsk->audit; + + audit_free_syscall(tsk); + /* Freeing the audit_task_info struct must be performed after + * audit_log_exit() due to need for loginuid and sessionid. + */ + info = tsk->audit; + tsk->audit = NULL; + kmem_cache_free(audit_task_cache, info);

diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 468a23390457..f00c1da587ea 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1612,7 +1615,6 @@ void __audit_free(struct task_struct *tsk) if (context->current_state == AUDIT_RECORD_CONTEXT) audit_log_exit(); } - audit_set_context(tsk, NULL); audit_free_context(context); }