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

From: Richard Guy Briggs
Date: Wed Jun 06 2018 - 13:01:18 EST


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@xxxxxxxxxx>
---
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