[RFC PATCH ghak90 (was ghak32) V3 04/10] audit: add support for non-syscall auxiliary records

[Richard Guy Briggs <rgb@redhat.com>]

Standalone audit records have the timestamp and serial number generated
on the fly and as such are unique, making them standalone.  This new
function audit_alloc_local() generates a local audit context that will
be used only for a standalone record and its auxiliary record(s).  The
context is discarded immediately after the local associated records are
produced.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
 include/linux/audit.h |  8 ++++++++
 kernel/auditsc.c      | 25 +++++++++++++++++++++++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index ab50985..f549121 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -232,7 +232,9 @@ struct audit_task_info {
 extern struct audit_task_info init_struct_audit;
 extern void __init audit_task_init(void);
 extern int  audit_alloc(struct task_struct *task);
+extern struct audit_context *audit_alloc_local(void);
 extern void audit_free(struct task_struct *task);
+extern void audit_free_context(struct audit_context *context);
 extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
 				  unsigned long a2, unsigned long a3);
 extern void __audit_syscall_exit(int ret_success, long ret_value);
@@ -493,6 +495,12 @@ static inline int audit_alloc(struct task_struct *task)
 {
 	return 0;
 }
+static inline struct audit_context *audit_alloc_local(void)
+{
+	return NULL;
+}
+static inline void audit_free_context(struct audit_context *context)
+{ }
 static inline void audit_free(struct task_struct *task)
 { }
 static inline void audit_syscall_entry(int major, unsigned long a0,
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index cface9d..81c9765 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -916,8 +916,11 @@ static inline void audit_free_aux(struct audit_context *context)
 static inline struct audit_context *audit_alloc_context(enum audit_state state)
 {
 	struct audit_context *context;
+	gfp_t gfpflags;
 
-	context = kzalloc(sizeof(*context), GFP_KERNEL);
+	/* We can be called in atomic context via audit_tg() */
+	gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
+	context = kzalloc(sizeof(*context), gfpflags);
 	if (!context)
 		return NULL;
 	context->state = state;
@@ -993,8 +996,26 @@ struct audit_task_info init_struct_audit = {
 	.ctx = NULL,
 };
 
-static inline void audit_free_context(struct audit_context *context)
+struct audit_context *audit_alloc_local(void)
 {
+	struct audit_context *context;
+
+	if (!audit_ever_enabled)
+		return NULL; /* Return if not auditing. */
+
+	context = audit_alloc_context(AUDIT_RECORD_CONTEXT);
+	if (!context)
+		return NULL;
+	context->serial = audit_serial();
+	context->ctime = current_kernel_time64();
+	context->in_syscall = 1;
+	return context;
+}
+
+void audit_free_context(struct audit_context *context)
+{
+	if (!context)
+		return;
 	audit_free_names(context);
 	unroll_tree_refs(context, NULL, 0);
 	free_tree_refs(context);
-- 
1.8.3.1