diff mbox series

[v26,21/25] audit: add support for non-syscall auxiliary records

Message ID 20210513200807.15910-22-casey@schaufler-ca.com (mailing list archive)
State New, archived
Headers show
Series LSM: Module stacking for AppArmor | expand

Commit Message

Casey Schaufler May 13, 2021, 8:08 p.m. UTC 
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>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: linux-audit@redhat.com
To: Richard Guy Briggs <rgb@redhat.com>
---
 include/linux/audit.h |  8 ++++++++
 kernel/audit.h        |  1 +
 kernel/auditsc.c      | 33 ++++++++++++++++++++++++++++-----
 3 files changed, 37 insertions(+), 5 deletions(-)

Comments

Paul Moore May 21, 2021, 8:19 p.m. UTC | #1 
On Thu, May 13, 2021 at 4:31 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>
> 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>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> Cc: linux-audit@redhat.com
> To: Richard Guy Briggs <rgb@redhat.com>
> ---
>  include/linux/audit.h |  8 ++++++++
>  kernel/audit.h        |  1 +
>  kernel/auditsc.c      | 33 ++++++++++++++++++++++++++++-----
>  3 files changed, 37 insertions(+), 5 deletions(-)

At some point I suspect we will need to add filtering for these
"local" records, but that is a problem for another day.

Acked-by: Paul Moore <paul@paul-moore.com>


--
paul moore
www.paul-moore.com
diff mbox series

Patch

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 418a485af114..97cd7471e572 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -289,6 +289,8 @@  static inline int audit_signal_info(int sig, struct task_struct *t)
 				/* Public API */
 extern int  audit_alloc(struct task_struct *task);
 extern void __audit_free(struct task_struct *task);
+extern struct audit_context *audit_alloc_local(gfp_t gfpflags);
+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);
@@ -552,6 +554,12 @@  static inline void audit_log_nfcfg(const char *name, u8 af,
 extern int audit_n_rules;
 extern int audit_signals;
 #else /* CONFIG_AUDITSYSCALL */
++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 int audit_alloc(struct task_struct *task)
 {
 	return 0;
diff --git a/kernel/audit.h b/kernel/audit.h
index 23a85a470121..27ef690afd30 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -99,6 +99,7 @@  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 67da23f6bebd..d4e061f95da8 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -925,11 +925,13 @@  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;
@@ -965,7 +967,8 @@  int audit_alloc(struct task_struct *tsk)
 		return 0;
 	}
 
-	if (!(context = audit_alloc_context(state))) {
+	context = audit_alloc_context(state, GFP_KERNEL);
+	if (!context) {
 		kfree(key);
 		audit_log_lost("out of memory in audit_alloc");
 		return -ENOMEM;
@@ -977,8 +980,27 @@  int audit_alloc(struct task_struct *tsk)
 	return 0;
 }
 
-static inline void audit_free_context(struct audit_context *context)
+struct audit_context *audit_alloc_local(gfp_t gfpflags)
 {
+	struct audit_context *context = NULL;
+
+	context = audit_alloc_context(AUDIT_RECORD_CONTEXT, gfpflags);
+	if (!context) {
+		audit_log_lost("out of memory in audit_alloc_local");
+		goto out;
+	}
+	context->serial = audit_serial();
+	ktime_get_coarse_real_ts64(&context->ctime);
+	context->local = true;
+out:
+	return context;
+}
+EXPORT_SYMBOL(audit_alloc_local);
+
+void audit_free_context(struct audit_context *context)
+{
+	if (!context)
+		return;
 	audit_free_module(context);
 	audit_free_names(context);
 	unroll_tree_refs(context, NULL, 0);
@@ -989,6 +1011,7 @@  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,
@@ -2210,7 +2233,7 @@  EXPORT_SYMBOL_GPL(__audit_inode_child);
 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();