Add inotify events for extended attributes and splice.

Splice, setxattr and removexattr should generate events. Note that VFS2 already
generates events for extended attributes.

Updates #1479.

PiperOrigin-RevId: 314244261

pkg/sentry/syscalls/linux/sys_splice.go

@@ -80,6 +80,12 @@ func doSplice(t *kernel.Task, outFile, inFile *fs.File, opts fs.SpliceOpts, nonB
 		}
 	}
 
+	if total > 0 {
+		// On Linux, inotify behavior is not very consistent with splice(2). We try
+		// our best to emulate Linux for very basic calls to splice, where for some
+		// reason, events are generated for output files, but not input files.
+		outFile.Dirent.InotifyEvent(linux.IN_MODIFY, 0)
+	}
 	return total, err
 }
 

pkg/sentry/syscalls/linux/sys_xattr.go

@@ -207,7 +207,11 @@ func setXattr(t *kernel.Task, d *fs.Dirent, nameAddr, valueAddr usermem.Addr, si
 		return syserror.EOPNOTSUPP
 	}
 
-	return d.Inode.SetXattr(t, d, name, value, flags)
+	if err := d.Inode.SetXattr(t, d, name, value, flags); err != nil {
+		return err
+	}
+	d.InotifyEvent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 func copyInXattrName(t *kernel.Task, nameAddr usermem.Addr) (string, error) {
@@ -418,7 +422,11 @@ func removeXattr(t *kernel.Task, d *fs.Dirent, nameAddr usermem.Addr) error {
 		return syserror.EOPNOTSUPP
 	}
 
-	return d.Inode.RemoveXattr(t, d, name)
+	if err := d.Inode.RemoveXattr(t, d, name); err != nil {
+		return err
+	}
+	d.InotifyEvent(linux.IN_ATTRIB, 0)
+	return nil
 }
 
 // LINT.ThenChange(vfs2/xattr.go)

pkg/sentry/syscalls/linux/vfs2/splice.go

@@ -187,6 +187,11 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 	if n == 0 {
 		return 0, nil, err
 	}
+
+	// On Linux, inotify behavior is not very consistent with splice(2). We try
+	// our best to emulate Linux for very basic calls to splice, where for some
+	// reason, events are generated for output files, but not input files.
+	outFile.Dentry().InotifyWithParent(linux.IN_MODIFY, 0, vfs.PathEvent)
 	return uintptr(n), nil, nil
 }
 

test/syscalls/linux/inotify.cc

@@ -19,6 +19,7 @@
 #include <sys/inotify.h>
 #include <sys/ioctl.h>
 #include <sys/time.h>
+#include <sys/xattr.h>
 
 #include <atomic>
 #include <list>
@@ -1655,9 +1656,44 @@ TEST(Inotify, EpollNoDeadlock) {
   }
 }
 
-TEST(Inotify, SpliceEvent) {
-  // TODO(gvisor.dev/issue/138): Implement splice in VFS2.
-  SKIP_IF(IsRunningOnGvisor() && !IsRunningWithVFS1());
+// On Linux, inotify behavior is not very consistent with splice(2). We try our
+// best to emulate Linux for very basic calls to splice.
+TEST(Inotify, SpliceOnWatchTarget) {
+  int pipes[2];
+  ASSERT_THAT(pipe2(pipes, O_NONBLOCK), SyscallSucceeds());
+
+  const TempPath dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  const FileDescriptor inotify_fd =
+      ASSERT_NO_ERRNO_AND_VALUE(InotifyInit1(IN_NONBLOCK));
+  const TempPath file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
+      dir.path(), "some content", TempPath::kDefaultFileMode));
+
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDWR));
+  const int dir_wd = ASSERT_NO_ERRNO_AND_VALUE(
+      InotifyAddWatch(inotify_fd.get(), dir.path(), IN_ALL_EVENTS));
+  const int file_wd = ASSERT_NO_ERRNO_AND_VALUE(
+      InotifyAddWatch(inotify_fd.get(), file.path(), IN_ALL_EVENTS));
+
+  EXPECT_THAT(splice(fd.get(), nullptr, pipes[1], nullptr, 1, /*flags=*/0),
+              SyscallSucceedsWithValue(1));
+
+  // Surprisingly, events are not generated in Linux if we read from a file.
+  std::vector<Event> events =
+      ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  ASSERT_THAT(events, Are({}));
+
+  EXPECT_THAT(splice(pipes[0], nullptr, fd.get(), nullptr, 1, /*flags=*/0),
+              SyscallSucceedsWithValue(1));
+
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  ASSERT_THAT(events, Are({
+                          Event(IN_MODIFY, dir_wd, Basename(file.path())),
+                          Event(IN_MODIFY, file_wd),
+                      }));
+}
+
+TEST(Inotify, SpliceOnInotifyFD) {
   int pipes[2];
   ASSERT_THAT(pipe2(pipes, O_NONBLOCK), SyscallSucceeds());
 
@@ -1719,6 +1755,58 @@ TEST(Inotify, LinkOnOtherParent) {
   EXPECT_THAT(events, Are({}));
 }
 
+TEST(Inotify, Xattr) {
+  // TODO(gvisor.dev/issue/1636): Support extended attributes in runsc gofer.
+  SKIP_IF(IsRunningOnGvisor());
+
+  const TempPath file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  const std::string path = file.path();
+  const FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(path, O_RDWR));
+  const FileDescriptor inotify_fd =
+      ASSERT_NO_ERRNO_AND_VALUE(InotifyInit1(IN_NONBLOCK));
+  const int wd = ASSERT_NO_ERRNO_AND_VALUE(
+      InotifyAddWatch(inotify_fd.get(), path, IN_ALL_EVENTS));
+
+  const char* cpath = path.c_str();
+  const char* name = "user.test";
+  int val = 123;
+  ASSERT_THAT(setxattr(cpath, name, &val, sizeof(val), /*flags=*/0),
+              SyscallSucceeds());
+  std::vector<Event> events =
+      ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({Event(IN_ATTRIB, wd)}));
+
+  ASSERT_THAT(getxattr(cpath, name, &val, sizeof(val)), SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({}));
+
+  char list[100];
+  ASSERT_THAT(listxattr(cpath, list, sizeof(list)), SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({}));
+
+  ASSERT_THAT(removexattr(cpath, name), SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({Event(IN_ATTRIB, wd)}));
+
+  ASSERT_THAT(fsetxattr(fd.get(), name, &val, sizeof(val), /*flags=*/0),
+              SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({Event(IN_ATTRIB, wd)}));
+
+  ASSERT_THAT(fgetxattr(fd.get(), name, &val, sizeof(val)), SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({}));
+
+  ASSERT_THAT(flistxattr(fd.get(), list, sizeof(list)), SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({}));
+
+  ASSERT_THAT(fremovexattr(fd.get(), name), SyscallSucceeds());
+  events = ASSERT_NO_ERRNO_AND_VALUE(DrainEvents(inotify_fd.get()));
+  EXPECT_THAT(events, Are({Event(IN_ATTRIB, wd)}));
+}
+
 TEST(Inotify, Exec) {
   const TempPath dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
   const TempPath bin = ASSERT_NO_ERRNO_AND_VALUE(