syscalls/fanotify22: Validate the generic error info

Implement some validation for the generic error info record emitted by
the kernel.  The error number is fs-specific but, well, we only support
ext4 for now anyway.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v2:
  - check for error record type in autotools (Amir)
Changes since v1:
  - Move defines to header file.

configure.ac

@@ -160,7 +160,8 @@ AC_CHECK_MEMBERS([struct utsname.domainname],,,[
 AC_CHECK_TYPES([enum kcmp_type],,,[#include <linux/kcmp.h>])
 AC_CHECK_TYPES([struct acct_v3],,,[#include <sys/acct.h>])
 AC_CHECK_TYPES([struct af_alg_iv, struct sockaddr_alg],,,[# include <linux/if_alg.h>])
-AC_CHECK_TYPES([struct fanotify_event_info_fid, struct fanotify_event_info_header],,,[#include <sys/fanotify.h>])
+AC_CHECK_TYPES([struct fanotify_event_info_fid, struct fanotify_event_info_header,
+		struct fanotify_event_info_error],[],[],[#include <sys/fanotify.h>])
 AC_CHECK_TYPES([struct file_dedupe_range],,,[#include <linux/fs.h>])
 
 AC_CHECK_TYPES([struct file_handle],,,[

testcases/kernel/syscalls/fanotify/fanotify.h

@@ -181,6 +181,9 @@ typedef struct {
 #ifndef FAN_EVENT_INFO_TYPE_PIDFD
 #define FAN_EVENT_INFO_TYPE_PIDFD	4
 #endif
+#ifndef FAN_EVENT_INFO_TYPE_ERROR
+#define FAN_EVENT_INFO_TYPE_ERROR	5
+#endif
 
 #ifndef HAVE_STRUCT_FANOTIFY_EVENT_INFO_HEADER
 struct fanotify_event_info_header {
@@ -205,6 +208,14 @@ struct fanotify_event_info_pidfd {
 };
 #endif /* HAVE_STRUCT_FANOTIFY_EVENT_INFO_PIDFD */
 
+#ifndef HAVE_STRUCT_FANOTIFY_EVENT_INFO_ERROR
+struct fanotify_event_info_error {
+	struct fanotify_event_info_header hdr;
+	__s32 error;
+	__u32 error_count;
+};
+#endif /* HAVE_STRUCT_FANOTIFY_EVENT_INFO_ERROR */
+
 /* NOTE: only for struct fanotify_event_info_fid */
 #ifdef HAVE_STRUCT_FANOTIFY_EVENT_INFO_FID_FSID___VAL
 # define FSID_VAL_MEMBER(fsid, i) (fsid.__val[i])
@@ -418,4 +429,25 @@ static inline int fanotify_mark_supported_by_kernel(uint64_t flag)
 		fanotify_events_supported_by_kernel(mask, init_flags, mark_type)); \
 } while (0)
 
+struct fanotify_event_info_header *get_event_info(
+					struct fanotify_event_metadata *event,
+					int info_type)
+{
+	struct fanotify_event_info_header *hdr = NULL;
+	char *start = (char *) event;
+	int off;
+
+	for (off = event->metadata_len; (off+sizeof(*hdr)) < event->event_len;
+	     off += hdr->len) {
+		hdr = (struct fanotify_event_info_header *) &(start[off]);
+		if (hdr->info_type == info_type)
+			return hdr;
+	}
+	return NULL;
+}
+
+#define get_event_info_error(event)					\
+	((struct fanotify_event_info_error *)				\
+	 get_event_info((event), FAN_EVENT_INFO_TYPE_ERROR))
+
 #endif /* __FANOTIFY_H__ */

testcases/kernel/syscalls/fanotify/fanotify22.c

@@ -48,14 +48,38 @@ static void trigger_fs_abort(void)
 
 static struct test_case {
 	char *name;
+	int error;
+	unsigned int error_count;
 	void (*trigger_error)(void);
 } testcases[] = {
 	{
 		.name = "Trigger abort",
 		.trigger_error = &trigger_fs_abort,
+		.error_count = 1,
+		.error = ESHUTDOWN,
 	},
 };
 
+int check_error_event_info_error(struct fanotify_event_info_error *info_error,
+				 const struct test_case *ex)
+{
+	int fail = 0;
+
+	if (info_error->error_count != ex->error_count) {
+		tst_res(TFAIL, "%s: Unexpected error_count (%d!=%d)",
+			ex->name, info_error->error_count, ex->error_count);
+		fail++;
+	}
+
+	if (info_error->error != ex->error) {
+		tst_res(TFAIL, "%s: Unexpected error code value (%d!=%d)",
+			ex->name, info_error->error, ex->error);
+		fail++;
+	}
+
+	return fail;
+}
+
 int check_error_event_metadata(struct fanotify_event_metadata *event)
 {
 	int fail = 0;
@@ -78,6 +102,8 @@ void check_event(char *buf, size_t len, const struct test_case *ex)
 {
 	struct fanotify_event_metadata *event =
 		(struct fanotify_event_metadata *) buf;
+	struct fanotify_event_info_error *info_error;
+	int fail = 0;
 
 	if (len < FAN_EVENT_METADATA_LEN) {
 		tst_res(TFAIL, "No event metadata found");
@@ -87,7 +113,16 @@ void check_event(char *buf, size_t len, const struct test_case *ex)
 	if (check_error_event_metadata(event))
 		return;
 
-	tst_res(TPASS, "Successfully received: %s", ex->name);
+	info_error = get_event_info_error(event);
+	if (info_error)
+		fail += check_error_event_info_error(info_error, ex);
+	else {
+		tst_res(TFAIL, "Generic error record not found");
+		fail++;
+	}
+
+	if (!fail)
+		tst_res(TPASS, "Successfully received: %s", ex->name);
 }
 
 static void do_test(unsigned int i)