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-rw-r--r--fs/verity/Makefile1
-rw-r--r--fs/verity/read_metadata.c55
2 files changed, 56 insertions, 0 deletions
diff --git a/fs/verity/Makefile b/fs/verity/Makefile
index 570e9136334d..435559a4fa9e 100644
--- a/fs/verity/Makefile
+++ b/fs/verity/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_FS_VERITY) += enable.o \
init.o \
measure.o \
open.o \
+ read_metadata.o \
verify.o
obj-$(CONFIG_FS_VERITY_BUILTIN_SIGNATURES) += signature.o
diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c
new file mode 100644
index 000000000000..43be990fd53e
--- /dev/null
+++ b/fs/verity/read_metadata.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Ioctl to read verity metadata
+ *
+ * Copyright 2021 Google LLC
+ */
+
+#include "fsverity_private.h"
+
+#include <linux/uaccess.h>
+
+/**
+ * fsverity_ioctl_read_metadata() - read verity metadata from a file
+ * @filp: file to read the metadata from
+ * @uarg: user pointer to fsverity_read_metadata_arg
+ *
+ * Return: length read on success, 0 on EOF, -errno on failure
+ */
+int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg)
+{
+ struct inode *inode = file_inode(filp);
+ const struct fsverity_info *vi;
+ struct fsverity_read_metadata_arg arg;
+ int length;
+ void __user *buf;
+
+ vi = fsverity_get_info(inode);
+ if (!vi)
+ return -ENODATA; /* not a verity file */
+ /*
+ * Note that we don't have to explicitly check that the file is open for
+ * reading, since verity files can only be opened for reading.
+ */
+
+ if (copy_from_user(&arg, uarg, sizeof(arg)))
+ return -EFAULT;
+
+ if (arg.__reserved)
+ return -EINVAL;
+
+ /* offset + length must not overflow. */
+ if (arg.offset + arg.length < arg.offset)
+ return -EINVAL;
+
+ /* Ensure that the return value will fit in INT_MAX. */
+ length = min_t(u64, arg.length, INT_MAX);
+
+ buf = u64_to_user_ptr(arg.buf_ptr);
+
+ switch (arg.metadata_type) {
+ default:
+ return -EINVAL;
+ }
+}
+EXPORT_SYMBOL_GPL(fsverity_ioctl_read_metadata);