[PATCH ghak90 (was ghak32) V4 05/10] audit: add support for non-syscall auxiliary records

Richard Guy Briggs
2018-07-31T20:07:40Z

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>
Acked-by: Serge Hallyn <serge@hallyn.com>
---
include/linux/audit.h | 8 ++++++++
kernel/audit.h | 1 +
kernel/auditsc.c | 33 ++++++++++++++++++++++++++++-----
3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 4f514ed..1f340ad 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -234,7 +234,9 @@ 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(gfp_t gfpflags);
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);
@@ -495,6 +497,12 @@ static inline int audit_alloc(struct task_struct *task)
{
return 0;
}
+static inline struct audit_context *audit_alloc_local(gfp_t gfpflags)
+{
+ 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/audit.h b/kernel/audit.h
index 1cf1c35..a6d00a5 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -110,6 +110,7 @@ struct audit_proctitle {
struct audit_context {
int dummy; /* must be the first element */
int in_syscall; /* 1 if task is in a syscall */
+ bool local; /* local context needed */
enum audit_state state, current_state;
unsigned int serial; /* serial number for record */
int major; /* syscall number */
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index cdb24cf..7627f21 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -913,11 +913,13 @@ static inline void audit_free_aux(struct audit_context *context)
}
}

-static inline struct audit_context *audit_alloc_context(enum audit_state state)
+static inline struct audit_context *audit_alloc_context(enum audit_state state,
+ gfp_t gfpflags)
{
struct audit_context *context;

- context = kzalloc(sizeof(*context), GFP_KERNEL);
+ /* We can be called in atomic context via audit_tg() */
+ context = kzalloc(sizeof(*context), gfpflags);
if (!context)
return NULL;
context->state = state;
@@ -970,7 +972,8 @@ int audit_alloc(struct task_struct *tsk)
return 0;
}

- if (!(context = audit_alloc_context(state))) {
+ context = audit_alloc_context(state, GFP_KERNEL);
+ if (!(context)) {
tsk->audit = NULL;
kmem_cache_free(audit_task_cache, info);
kfree(key);
@@ -991,8 +994,27 @@ 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(gfp_t gfpflags)
{
+ struct audit_context *context;
+
+ if (!audit_ever_enabled)
+ return NULL; /* Return if not auditing. */
+
+ context = audit_alloc_context(AUDIT_RECORD_CONTEXT, gfpflags);
+ if (!context)
+ return NULL;
+ context->serial = audit_serial();
+ context->ctime = current_kernel_time64();
+ context->local = true;
+ return context;
+}
+EXPORT_SYMBOL(audit_alloc_local);
+
+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);
@@ -1002,6 +1024,7 @@ static inline void audit_free_context(struct audit_context *context)
audit_proctitle_free(context);
kfree(context);
}
+EXPORT_SYMBOL(audit_free_context);

static int audit_log_pid_context(struct audit_context *context, pid_t pid,
kuid_t auid, kuid_t uid, unsigned int sessionid,
@@ -2024,7 +2047,7 @@ void __audit_inode_child(struct inode *parent,
int auditsc_get_stamp(struct audit_context *ctx,
struct timespec64 *t, unsigned int *serial)
{
- if (!ctx->in_syscall)
+ if (!ctx->in_syscall && !ctx->local)
return 0;
if (!ctx->serial)
ctx->serial = audit_serial();
--
1.8.3.1