linux-ext4 - [PATCH v2 05/10] syscalls/fanotify20: Validate incoming FID in FAN_FS

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Message-Id: <20211026184239.151156-6-krisman@collabora.com>
Date:   Tue, 26 Oct 2021 15:42:34 -0300
From:   Gabriel Krisman Bertazi <krisman@...labora.com>
To:     ltp@...ts.linux.it, jack@...e.com, amir73il@...il.com
Cc:     khazhy@...gle.com, kernel@...labora.com,
        linux-ext4@...r.kernel.org, repnop@...gle.com,
        Gabriel Krisman Bertazi <krisman@...labora.com>
Subject: [PATCH v2 05/10] syscalls/fanotify20: Validate incoming FID in FAN_FS_ERROR

Verify the FID provided in the event.  If the FH has size 0, this is
assumed to be a superblock error (i.e. null FH).

Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

---
Changes since v1:
  - Move defines to header file.
  - Use 0-len FH for sb error
---
 testcases/kernel/syscalls/fanotify/fanotify.h |  4 ++
 .../kernel/syscalls/fanotify/fanotify20.c     | 63 +++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/testcases/kernel/syscalls/fanotify/fanotify.h b/testcases/kernel/syscalls/fanotify/fanotify.h
index 58e30aaf00bc..9bff3cf1a3fe 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify.h
+++ b/testcases/kernel/syscalls/fanotify/fanotify.h
@@ -435,4 +435,8 @@ struct fanotify_event_info_header *get_event_info(
 	((struct fanotify_event_info_error *)				\
 	 get_event_info((event), FAN_EVENT_INFO_TYPE_ERROR))
 
+#define get_event_info_fid(event)					\
+	((struct fanotify_event_info_fid *)				\
+	 get_event_info((event), FAN_EVENT_INFO_TYPE_FID))
+
 #endif /* __FANOTIFY_H__ */
diff --git a/testcases/kernel/syscalls/fanotify/fanotify20.c b/testcases/kernel/syscalls/fanotify/fanotify20.c
index 6074d449ae63..220cd51419e8 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify20.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify20.c
@@ -34,20 +34,61 @@
 #ifdef HAVE_SYS_FANOTIFY_H
 #include "fanotify.h"
 
+#ifndef FILEID_INVALID
+#define	FILEID_INVALID		0xff
+#endif
+
 #define BUF_SIZE 256
 static char event_buf[BUF_SIZE];
 int fd_notify;
 
 #define MOUNT_PATH "test_mnt"
 
+/* These expected FIDs are common to multiple tests */
+static struct fanotify_fid_t null_fid;
+
 static struct test_case {
 	char *name;
 	int error;
 	unsigned int error_count;
+	struct fanotify_fid_t *fid;
 	void (*trigger_error)(void);
 } testcases[] = {
 };
 
+int check_error_event_info_fid(struct fanotify_event_info_fid *fid,
+				 const struct test_case *ex)
+{
+	struct file_handle *fh = (struct file_handle *) &fid->handle;
+
+	if (memcmp(&fid->fsid, &ex->fid->fsid, sizeof(fid->fsid))) {
+		tst_res(TFAIL, "%s: Received bad FSID type (%x...!=%x...)",
+			ex->name, FSID_VAL_MEMBER(fid->fsid, 0),
+			FSID_VAL_MEMBER(ex->fid->fsid, 0));
+
+		return 1;
+	}
+	if (fh->handle_type != ex->fid->handle.handle_type) {
+		tst_res(TFAIL, "%s: Received bad file_handle type (%d!=%d)",
+			ex->name, fh->handle_type, ex->fid->handle.handle_type);
+		return 1;
+	}
+
+	if (fh->handle_bytes != ex->fid->handle.handle_bytes) {
+		tst_res(TFAIL, "%s: Received bad file_handle len (%d!=%d)",
+			ex->name, fh->handle_bytes, ex->fid->handle.handle_bytes);
+		return 1;
+	}
+
+	if (memcmp(fh->f_handle, ex->fid->handle.f_handle, fh->handle_bytes)) {
+		tst_res(TFAIL, "%s: Received wrong handle. "
+			"Expected (%x...) got (%x...) ", ex->name,
+			*(int*)ex->fid->handle.f_handle, *(int*)fh->f_handle);
+		return 1;
+	}
+	return 0;
+}
+
 int check_error_event_info_error(struct fanotify_event_info_error *info_error,
 				 const struct test_case *ex)
 {
@@ -91,6 +132,7 @@ 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;
+	struct fanotify_event_info_fid *info_fid;
 	int fail = 0;
 
 	if (len < FAN_EVENT_METADATA_LEN) {
@@ -109,6 +151,14 @@ void check_event(char *buf, size_t len, const struct test_case *ex)
 		fail++;
 	}
 
+	info_fid = get_event_info_fid(event);
+	if (info_fid)
+		fail += check_error_event_info_fid(info_fid, ex);
+	else {
+		tst_res(TFAIL, "FID record not found");
+		fail++;
+	}
+
 	if (!fail)
 		tst_res(TPASS, "Successfully received: %s", ex->name);
 }
@@ -125,12 +175,25 @@ static void do_test(unsigned int i)
 	check_event(event_buf, read_len, tcase);
 }
 
+static void init_null_fid(void)
+{
+	/* Use fanotify_save_fid to fill the fsid and overwrite the
+	 * file_handler to create a null_fid
+	 */
+	fanotify_save_fid(MOUNT_PATH, &null_fid);
+
+	null_fid.handle.handle_type = FILEID_INVALID;
+	null_fid.handle.handle_bytes = 0;
+}
+
 static void setup(void)
 {
 	REQUIRE_FANOTIFY_EVENTS_SUPPORTED_ON_FS(FAN_CLASS_NOTIF|FAN_REPORT_FID,
 						FAN_MARK_FILESYSTEM,
 						FAN_FS_ERROR, ".");
 
+	init_null_fid();
+
 	fd_notify = SAFE_FANOTIFY_INIT(FAN_CLASS_NOTIF|FAN_REPORT_FID,
 				       O_RDONLY);
 
-- 
2.33.0