1 files changed, 52 insertions, 11 deletions

diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index ecc604e61d61..40f14e5fed9d 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -12,8 +12,19 @@
 #define _LINUX_FSVERITY_H
 
 #include <linux/fs.h>
+#include <crypto/hash_info.h>
+#include <crypto/sha2.h>
 #include <uapi/linux/fsverity.h>
 
+/*
+ * Largest digest size among all hash algorithms supported by fs-verity.
+ * Currently assumed to be <= size of fsverity_descriptor::root_hash.
+ */
+#define FS_VERITY_MAX_DIGEST_SIZE	SHA512_DIGEST_SIZE
+
+/* Arbitrary limit to bound the kmalloc() size.  Can be changed. */
+#define FS_VERITY_MAX_DESCRIPTOR_SIZE	16384
+
 /* Verity operations for filesystems */
 struct fsverity_operations {
 
@@ -115,29 +126,41 @@ struct fsverity_operations {
 
 static inline struct fsverity_info *fsverity_get_info(const struct inode *inode)
 {
-	/* pairs with the cmpxchg() in fsverity_set_info() */
-	return READ_ONCE(inode->i_verity_info);
+	/*
+	 * Pairs with the cmpxchg_release() in fsverity_set_info().
+	 * I.e., another task may publish ->i_verity_info concurrently,
+	 * executing a RELEASE barrier.  We need to use smp_load_acquire() here
+	 * to safely ACQUIRE the memory the other task published.
+	 */
+	return smp_load_acquire(&inode->i_verity_info);
 }
 
 /* enable.c */
 
-extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg);
+int fsverity_ioctl_enable(struct file *filp, const void __user *arg);
 
 /* measure.c */
 
-extern int fsverity_ioctl_measure(struct file *filp, void __user *arg);
+int fsverity_ioctl_measure(struct file *filp, void __user *arg);
+int fsverity_get_digest(struct inode *inode,
+			u8 digest[FS_VERITY_MAX_DIGEST_SIZE],
+			enum hash_algo *alg);
 
 /* open.c */
 
-extern int fsverity_file_open(struct inode *inode, struct file *filp);
-extern int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr);
-extern void fsverity_cleanup_inode(struct inode *inode);
+int fsverity_file_open(struct inode *inode, struct file *filp);
+int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr);
+void fsverity_cleanup_inode(struct inode *inode);
+
+/* read_metadata.c */
+
+int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg);
 
 /* verify.c */
 
-extern bool fsverity_verify_page(struct page *page);
-extern void fsverity_verify_bio(struct bio *bio);
-extern void fsverity_enqueue_verify_work(struct work_struct *work);
+bool fsverity_verify_page(struct page *page);
+void fsverity_verify_bio(struct bio *bio);
+void fsverity_enqueue_verify_work(struct work_struct *work);
 
 #else /* !CONFIG_FS_VERITY */
 
@@ -161,6 +184,13 @@ static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg)
 	return -EOPNOTSUPP;
 }
 
+static inline int fsverity_get_digest(struct inode *inode,
+				      u8 digest[FS_VERITY_MAX_DIGEST_SIZE],
+				      enum hash_algo *alg)
+{
+	return -EOPNOTSUPP;
+}
+
 /* open.c */
 
 static inline int fsverity_file_open(struct inode *inode, struct file *filp)
@@ -178,6 +208,14 @@ static inline void fsverity_cleanup_inode(struct inode *inode)
 {
 }
 
+/* read_metadata.c */
+
+static inline int fsverity_ioctl_read_metadata(struct file *filp,
+					       const void __user *uarg)
+{
+	return -EOPNOTSUPP;
+}
+
 /* verify.c */
 
 static inline bool fsverity_verify_page(struct page *page)
@@ -200,13 +238,16 @@ static inline void fsverity_enqueue_verify_work(struct work_struct *work)
 
 /**
  * fsverity_active() - do reads from the inode need to go through fs-verity?
+ * @inode: inode to check
  *
  * This checks whether ->i_verity_info has been set.
  *
- * Filesystems call this from ->readpages() to check whether the pages need to
+ * Filesystems call this from ->readahead() to check whether the pages need to
  * be verified or not.  Don't use IS_VERITY() for this purpose; it's subject to
  * a race condition where the file is being read concurrently with
  * FS_IOC_ENABLE_VERITY completing.  (S_VERITY is set before ->i_verity_info.)
+ *
+ * Return: true if reads need to go through fs-verity, otherwise false
  */
 static inline bool fsverity_active(const struct inode *inode)
 {