Fix procfs bugs in vfs2.

- Support writing on proc/[pid]/{uid,gid}map
- Return EIO for writing to static files.

Updates #2923.

PiperOrigin-RevId: 318188503

2 files changed, 5 insertions, 5 deletions

diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index 1e66997ce..3fec0d6d6 100644
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -327,7 +327,7 @@ func (fd *DynamicBytesFileDescriptionImpl) pwriteLocked(ctx context.Context, src
 
 	writable, ok := fd.data.(WritableDynamicBytesSource)
 	if !ok {
-		return 0, syserror.EINVAL
+		return 0, syserror.EIO
 	}
 	n, err := writable.Write(ctx, src, offset)
 	if err != nil {
diff --git a/pkg/sentry/vfs/file_description_impl_util_test.go b/pkg/sentry/vfs/file_description_impl_util_test.go
index 5061f6ac9..3b7e1c273 100644
--- a/pkg/sentry/vfs/file_description_impl_util_test.go
+++ b/pkg/sentry/vfs/file_description_impl_util_test.go
@@ -155,11 +155,11 @@ func TestGenCountFD(t *testing.T) {
 	}
 
 	// Write and PWrite fails.
-	if _, err := fd.Write(ctx, ioseq, WriteOptions{}); err != syserror.EINVAL {
-		t.Errorf("Write: got err %v, wanted %v", err, syserror.EINVAL)
+	if _, err := fd.Write(ctx, ioseq, WriteOptions{}); err != syserror.EIO {
+		t.Errorf("Write: got err %v, wanted %v", err, syserror.EIO)
 	}
-	if _, err := fd.PWrite(ctx, ioseq, 0, WriteOptions{}); err != syserror.EINVAL {
-		t.Errorf("Write: got err %v, wanted %v", err, syserror.EINVAL)
+	if _, err := fd.PWrite(ctx, ioseq, 0, WriteOptions{}); err != syserror.EIO {
+		t.Errorf("Write: got err %v, wanted %v", err, syserror.EIO)
 	}
 }