2 files changed, 167 insertions, 94 deletions

diff --git a/kernel/audit.h b/kernel/audit.h
index d6a2c899a8db..13abc48de0bd 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -100,7 +100,10 @@ struct audit_proctitle {
 /* The per-task audit context. */
 struct audit_context {
 	int		    dummy;	/* must be the first element */
-	int		    in_syscall;	/* 1 if task is in a syscall */
+	enum {
+		AUDIT_CTX_UNUSED,	/* audit_context is currently unused */
+		AUDIT_CTX_SYSCALL,	/* in use by syscall */
+	} context;
 	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 8dd73a64f921..f3d309b05c2d 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -915,10 +915,80 @@ static inline void audit_free_aux(struct audit_context *context)
 		context->aux = aux->next;
 		kfree(aux);
 	}
+	context->aux = NULL;
 	while ((aux = context->aux_pids)) {
 		context->aux_pids = aux->next;
 		kfree(aux);
 	}
+	context->aux_pids = NULL;
+}
+
+/**
+ * audit_reset_context - reset a audit_context structure
+ * @ctx: the audit_context to reset
+ *
+ * All fields in the audit_context will be reset to an initial state, all
+ * references held by fields will be dropped, and private memory will be
+ * released.  When this function returns the audit_context will be suitable
+ * for reuse, so long as the passed context is not NULL or a dummy context.
+ */
+static void audit_reset_context(struct audit_context *ctx)
+{
+	if (!ctx)
+		return;
+
+	/* if ctx is non-null, reset the "ctx->state" regardless */
+	ctx->context = AUDIT_CTX_UNUSED;
+	if (ctx->dummy)
+		return;
+
+	/*
+	 * NOTE: It shouldn't matter in what order we release the fields, so
+	 *       release them in the order in which they appear in the struct;
+	 *       this gives us some hope of quickly making sure we are
+	 *       resetting the audit_context properly.
+	 *
+	 *       Other things worth mentioning:
+	 *       - we don't reset "dummy"
+	 *       - we don't reset "state", we do reset "current_state"
+	 *       - we preserve "filterkey" if "state" is AUDIT_STATE_RECORD
+	 *       - much of this is likely overkill, but play it safe for now
+	 *       - we really need to work on improving the audit_context struct
+	 */
+
+	ctx->current_state = ctx->state;
+	ctx->serial = 0;
+	ctx->major = 0;
+	ctx->ctime = (struct timespec64){ .tv_sec = 0, .tv_nsec = 0 };
+	memset(ctx->argv, 0, sizeof(ctx->argv));
+	ctx->return_code = 0;
+	ctx->prio = (ctx->state == AUDIT_STATE_RECORD ? ~0ULL : 0);
+	ctx->return_valid = AUDITSC_INVALID;
+	audit_free_names(ctx);
+	if (ctx->state != AUDIT_STATE_RECORD) {
+		kfree(ctx->filterkey);
+		ctx->filterkey = NULL;
+	}
+	audit_free_aux(ctx);
+	kfree(ctx->sockaddr);
+	ctx->sockaddr = NULL;
+	ctx->sockaddr_len = 0;
+	ctx->pid = ctx->ppid = 0;
+	ctx->uid = ctx->euid = ctx->suid = ctx->fsuid = KUIDT_INIT(0);
+	ctx->gid = ctx->egid = ctx->sgid = ctx->fsgid = KGIDT_INIT(0);
+	ctx->personality = 0;
+	ctx->arch = 0;
+	ctx->target_pid = 0;
+	ctx->target_auid = ctx->target_uid = KUIDT_INIT(0);
+	ctx->target_sessionid = 0;
+	ctx->target_sid = 0;
+	ctx->target_comm[0] = '\0';
+	unroll_tree_refs(ctx, NULL, 0);
+	WARN_ON(!list_empty(&ctx->killed_trees));
+	ctx->type = 0;
+	audit_free_module(ctx);
+	ctx->fds[0] = -1;
+	audit_proctitle_free(ctx);
 }
 
 static inline struct audit_context *audit_alloc_context(enum audit_state state)
@@ -928,6 +998,7 @@ static inline struct audit_context *audit_alloc_context(enum audit_state state)
 	context = kzalloc(sizeof(*context), GFP_KERNEL);
 	if (!context)
 		return NULL;
+	context->context = AUDIT_CTX_UNUSED;
 	context->state = state;
 	context->prio = state == AUDIT_STATE_RECORD ? ~0ULL : 0;
 	INIT_LIST_HEAD(&context->killed_trees);
@@ -953,7 +1024,7 @@ int audit_alloc(struct task_struct *tsk)
 	char *key = NULL;
 
 	if (likely(!audit_ever_enabled))
-		return 0; /* Return if not auditing. */
+		return 0;
 
 	state = audit_filter_task(tsk, &key);
 	if (state == AUDIT_STATE_DISABLED) {
@@ -975,14 +1046,10 @@ int audit_alloc(struct task_struct *tsk)
 
 static inline void audit_free_context(struct audit_context *context)
 {
-	audit_free_module(context);
-	audit_free_names(context);
-	unroll_tree_refs(context, NULL, 0);
+	/* resetting is extra work, but it is likely just noise */
+	audit_reset_context(context);
 	free_tree_refs(context);
-	audit_free_aux(context);
 	kfree(context->filterkey);
-	kfree(context->sockaddr);
-	audit_proctitle_free(context);
 	kfree(context);
 }
 
@@ -1489,29 +1556,35 @@ static void audit_log_exit(void)
 
 	context->personality = current->personality;
 
-	ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL);
-	if (!ab)
-		return;		/* audit_panic has been called */
-	audit_log_format(ab, "arch=%x syscall=%d",
-			 context->arch, context->major);
-	if (context->personality != PER_LINUX)
-		audit_log_format(ab, " per=%lx", context->personality);
-	if (context->return_valid != AUDITSC_INVALID)
-		audit_log_format(ab, " success=%s exit=%ld",
-				 (context->return_valid==AUDITSC_SUCCESS)?"yes":"no",
-				 context->return_code);
-
-	audit_log_format(ab,
-			 " a0=%lx a1=%lx a2=%lx a3=%lx items=%d",
-			 context->argv[0],
-			 context->argv[1],
-			 context->argv[2],
-			 context->argv[3],
-			 context->name_count);
-
-	audit_log_task_info(ab);
-	audit_log_key(ab, context->filterkey);
-	audit_log_end(ab);
+	switch (context->context) {
+	case AUDIT_CTX_SYSCALL:
+		ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL);
+		if (!ab)
+			return;
+		audit_log_format(ab, "arch=%x syscall=%d",
+				 context->arch, context->major);
+		if (context->personality != PER_LINUX)
+			audit_log_format(ab, " per=%lx", context->personality);
+		if (context->return_valid != AUDITSC_INVALID)
+			audit_log_format(ab, " success=%s exit=%ld",
+					 (context->return_valid == AUDITSC_SUCCESS ?
+					  "yes" : "no"),
+					 context->return_code);
+		audit_log_format(ab,
+				 " a0=%lx a1=%lx a2=%lx a3=%lx items=%d",
+				 context->argv[0],
+				 context->argv[1],
+				 context->argv[2],
+				 context->argv[3],
+				 context->name_count);
+		audit_log_task_info(ab);
+		audit_log_key(ab, context->filterkey);
+		audit_log_end(ab);
+		break;
+	default:
+		BUG();
+		break;
+	}
 
 	for (aux = context->aux; aux; aux = aux->next) {
 
@@ -1602,14 +1675,15 @@ static void audit_log_exit(void)
 		audit_log_name(context, n, NULL, i++, &call_panic);
 	}
 
-	audit_log_proctitle();
+	if (context->context == AUDIT_CTX_SYSCALL)
+		audit_log_proctitle();
 
 	/* Send end of event record to help user space know we are finished */
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE);
 	if (ab)
 		audit_log_end(ab);
 	if (call_panic)
-		audit_panic("error converting sid to string");
+		audit_panic("error in audit_log_exit()");
 }
 
 /**
@@ -1625,6 +1699,7 @@ void __audit_free(struct task_struct *tsk)
 	if (!context)
 		return;
 
+	/* this may generate CONFIG_CHANGE records */
 	if (!list_empty(&context->killed_trees))
 		audit_kill_trees(context);
 
@@ -1633,7 +1708,8 @@ void __audit_free(struct task_struct *tsk)
 	 * random task_struct that doesn't doesn't have any meaningful data we
 	 * need to log via audit_log_exit().
 	 */
-	if (tsk == current && !context->dummy && context->in_syscall) {
+	if (tsk == current && !context->dummy &&
+	    context->context == AUDIT_CTX_SYSCALL) {
 		context->return_valid = AUDITSC_INVALID;
 		context->return_code = 0;
 
@@ -1648,6 +1724,34 @@ void __audit_free(struct task_struct *tsk)
 }
 
 /**
+ * audit_return_fixup - fixup the return codes in the audit_context
+ * @ctx: the audit_context
+ * @success: true/false value to indicate if the operation succeeded or not
+ * @code: operation return code
+ *
+ * We need to fixup the return code in the audit logs if the actual return
+ * codes are later going to be fixed by the arch specific signal handlers.
+ */
+static void audit_return_fixup(struct audit_context *ctx,
+			       int success, long code)
+{
+	/*
+	 * This is actually a test for:
+	 * (rc == ERESTARTSYS ) || (rc == ERESTARTNOINTR) ||
+	 * (rc == ERESTARTNOHAND) || (rc == ERESTART_RESTARTBLOCK)
+	 *
+	 * but is faster than a bunch of ||
+	 */
+	if (unlikely(code <= -ERESTARTSYS) &&
+	    (code >= -ERESTART_RESTARTBLOCK) &&
+	    (code != -ENOIOCTLCMD))
+		ctx->return_code = -EINTR;
+	else
+		ctx->return_code  = code;
+	ctx->return_valid = (success ? AUDITSC_SUCCESS : AUDITSC_FAILURE);
+}
+
+/**
  * __audit_syscall_entry - fill in an audit record at syscall entry
  * @major: major syscall type (function)
  * @a1: additional syscall register 1
@@ -1672,7 +1776,12 @@ void __audit_syscall_entry(int major, unsigned long a1, unsigned long a2,
 	if (!audit_enabled || !context)
 		return;
 
-	BUG_ON(context->in_syscall || context->name_count);
+	WARN_ON(context->context != AUDIT_CTX_UNUSED);
+	WARN_ON(context->name_count);
+	if (context->context != AUDIT_CTX_UNUSED || context->name_count) {
+		audit_panic("unrecoverable error in audit_syscall_entry()");
+		return;
+	}
 
 	state = context->state;
 	if (state == AUDIT_STATE_DISABLED)
@@ -1691,10 +1800,8 @@ void __audit_syscall_entry(int major, unsigned long a1, unsigned long a2,
 	context->argv[1]    = a2;
 	context->argv[2]    = a3;
 	context->argv[3]    = a4;
-	context->serial     = 0;
-	context->in_syscall = 1;
+	context->context = AUDIT_CTX_SYSCALL;
 	context->current_state  = state;
-	context->ppid       = 0;
 	ktime_get_coarse_real_ts64(&context->ctime);
 }
 
@@ -1711,63 +1818,27 @@ void __audit_syscall_entry(int major, unsigned long a1, unsigned long a2,
  */
 void __audit_syscall_exit(int success, long return_code)
 {
-	struct audit_context *context;
+	struct audit_context *context = audit_context();
 
-	context = audit_context();
-	if (!context)
-		return;
+	if (!context || context->dummy ||
+	    context->context != AUDIT_CTX_SYSCALL)
+		goto out;
 
+	/* this may generate CONFIG_CHANGE records */
 	if (!list_empty(&context->killed_trees))
 		audit_kill_trees(context);
 
-	if (!context->dummy && context->in_syscall) {
-		if (success)
-			context->return_valid = AUDITSC_SUCCESS;
-		else
-			context->return_valid = AUDITSC_FAILURE;
-
-		/*
-		 * we need to fix up the return code in the audit logs if the
-		 * actual return codes are later going to be fixed up by the
-		 * arch specific signal handlers
-		 *
-		 * This is actually a test for:
-		 * (rc == ERESTARTSYS ) || (rc == ERESTARTNOINTR) ||
-		 * (rc == ERESTARTNOHAND) || (rc == ERESTART_RESTARTBLOCK)
-		 *
-		 * but is faster than a bunch of ||
-		 */
-		if (unlikely(return_code <= -ERESTARTSYS) &&
-		    (return_code >= -ERESTART_RESTARTBLOCK) &&
-		    (return_code != -ENOIOCTLCMD))
-			context->return_code = -EINTR;
-		else
-			context->return_code  = return_code;
-
-		audit_filter_syscall(current, context);
-		audit_filter_inodes(current, context);
-		if (context->current_state == AUDIT_STATE_RECORD)
-			audit_log_exit();
-	}
+	/* run through both filters to ensure we set the filterkey properly */
+	audit_filter_syscall(current, context);
+	audit_filter_inodes(current, context);
+	if (context->current_state < AUDIT_STATE_RECORD)
+		goto out;
 
-	context->in_syscall = 0;
-	context->prio = context->state == AUDIT_STATE_RECORD ? ~0ULL : 0;
+	audit_return_fixup(context, success, return_code);
+	audit_log_exit();
 
-	audit_free_module(context);
-	audit_free_names(context);
-	unroll_tree_refs(context, NULL, 0);
-	audit_free_aux(context);
-	context->aux = NULL;
-	context->aux_pids = NULL;
-	context->target_pid = 0;
-	context->target_sid = 0;
-	context->sockaddr_len = 0;
-	context->type = 0;
-	context->fds[0] = -1;
-	if (context->state != AUDIT_STATE_RECORD) {
-		kfree(context->filterkey);
-		context->filterkey = NULL;
-	}
+out:
+	audit_reset_context(context);
 }
 
 static inline void handle_one(const struct inode *inode)
@@ -1919,7 +1990,7 @@ void __audit_getname(struct filename *name)
 	struct audit_context *context = audit_context();
 	struct audit_names *n;
 
-	if (!context->in_syscall)
+	if (context->context == AUDIT_CTX_UNUSED)
 		return;
 
 	n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
@@ -1991,7 +2062,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 	struct list_head *list = &audit_filter_list[AUDIT_FILTER_FS];
 	int i;
 
-	if (!context->in_syscall)
+	if (context->context == AUDIT_CTX_UNUSED)
 		return;
 
 	rcu_read_lock();
@@ -2109,7 +2180,7 @@ void __audit_inode_child(struct inode *parent,
 	struct list_head *list = &audit_filter_list[AUDIT_FILTER_FS];
 	int i;
 
-	if (!context->in_syscall)
+	if (context->context == AUDIT_CTX_UNUSED)
 		return;
 
 	rcu_read_lock();
@@ -2208,7 +2279,7 @@ 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->context == AUDIT_CTX_UNUSED)
 		return 0;
 	if (!ctx->serial)
 		ctx->serial = audit_serial();
@@ -2706,8 +2777,7 @@ void audit_seccomp_actions_logged(const char *names, const char *old_names,
 struct list_head *audit_killed_trees(void)
 {
 	struct audit_context *ctx = audit_context();
-
-	if (likely(!ctx || !ctx->in_syscall))
+	if (likely(!ctx || ctx->context == AUDIT_CTX_UNUSED))
 		return NULL;
 	return &ctx->killed_trees;
 }