verify framework.

grub-core/commands/verify_helper.c

@@ -0,0 +1,172 @@
+#include <grub/file.h>
+#include <grub/verify.h>
+#include <grub/dl.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+struct grub_file_verifier *grub_file_verifiers;
+
+struct grub_verified
+{
+  grub_file_t file;
+  void *buf;
+};
+typedef struct grub_verified *grub_verified_t;
+
+static void
+verified_free (grub_verified_t verified)
+{
+  if (verified)
+    {
+      grub_free (verified->buf);
+      grub_free (verified);
+    }
+}
+
+static grub_ssize_t
+verified_read (struct grub_file *file, char *buf, grub_size_t len)
+{
+  grub_verified_t verified = file->data;
+
+  grub_memcpy (buf, (char *) verified->buf + file->offset, len);
+  return len;
+}
+
+static grub_err_t
+verified_close (struct grub_file *file)
+{
+  grub_verified_t verified = file->data;
+
+  grub_file_close (verified->file);
+  verified_free (verified);
+  file->data = 0;
+
+  /* device and name are freed by parent */
+  file->device = 0;
+  file->name = 0;
+
+  return grub_errno;
+}
+
+struct grub_fs verified_fs =
+{
+  .name = "verified_read",
+  .read = verified_read,
+  .close = verified_close
+};
+
+static grub_file_t
+grub_verify_helper_open (grub_file_t io, enum grub_file_type type)
+{
+  grub_verified_t verified = 0;
+  struct grub_file_verifier *ver;
+  void *context;
+  grub_file_t ret = 0;
+  grub_err_t err;
+
+  if ((type & GRUB_FILE_TYPE_MASK) == GRUB_FILE_TYPE_SIGNATURE
+      || (type & GRUB_FILE_TYPE_MASK) == GRUB_FILE_TYPE_VERIFY_SIGNATURE
+      || (type & GRUB_FILE_TYPE_SKIP_SIGNATURE))
+    return io;
+
+  if (io->device->disk && 
+      (io->device->disk->dev->id == GRUB_DISK_DEVICE_MEMDISK_ID
+       || io->device->disk->dev->id == GRUB_DISK_DEVICE_PROCFS_ID))
+    return io;
+
+  FOR_LIST_ELEMENTS(ver, grub_file_verifiers)
+    {
+      enum grub_verify_flags flags = 0;
+      err = ver->init (io, type, &context, &flags);
+      if (err)
+	goto fail_noclose;
+      if (!(flags & GRUB_VERIFY_FLAGS_SKIP_VERIFICATION))
+	break;
+    }
+  if (!ver)
+    /* No verifiers wanted to verify. Just return underlying file.  */
+    return io;
+
+  ret = grub_malloc (sizeof (*ret));
+  if (!ret)
+    {
+      goto fail;
+    }
+  *ret = *io;
+
+  ret->fs = &verified_fs;
+  ret->not_easily_seekable = 0;
+  if (ret->size >> (sizeof (grub_size_t) * GRUB_CHAR_BIT - 1))
+    {
+      grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
+		  "big file signature isn't implemented yet");
+      goto fail;
+    }
+  verified = grub_malloc (sizeof (*verified));
+  if (!verified)
+    {
+      goto fail;
+    }
+  verified->buf = grub_malloc (ret->size);
+  if (!verified->buf)
+    {
+      goto fail;
+    }
+  if (grub_file_read (io, verified->buf, ret->size) != (grub_ssize_t) ret->size)
+    {
+      if (!grub_errno)
+	grub_error (GRUB_ERR_FILE_READ_ERROR, N_("premature end of file %s"),
+		    io->name);
+      goto fail;
+    }
+  
+  err = ver->write (context, verified->buf, ret->size);
+  if (err)
+    goto fail;
+
+  err = ver->fini (context);
+  if (err)
+    goto fail;
+
+  ver->close (context);
+
+  FOR_LIST_ELEMENTS_NEXT(ver, grub_file_verifiers)
+    {
+      enum grub_verify_flags flags = 0;
+      err = ver->init (io, type, &context, &flags);
+      if (err)
+	goto fail_noclose;
+      if (flags & GRUB_VERIFY_FLAGS_SKIP_VERIFICATION)
+	continue;
+      err = ver->write (context, verified->buf, ret->size);
+      if (err)
+	goto fail;
+
+      err = ver->fini (context);
+      if (err)
+	goto fail;
+
+      ver->close (context);
+    }
+
+  verified->file = io;
+  ret->data = verified;
+  return ret;
+
+ fail:
+  ver->close (context);
+ fail_noclose:
+  verified_free (verified);
+  grub_free (ret);
+  return NULL;
+}
+
+GRUB_MOD_INIT(verify_helper)
+{
+  grub_file_filter_register (GRUB_FILE_FILTER_VERIFY, grub_verify_helper_open);
+}
+
+GRUB_MOD_FINI(verify_helper)
+{
+  grub_file_filter_unregister (GRUB_FILE_FILTER_VERIFY);
+}