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authorEric Biggers <ebiggers@google.com>2019-07-22 19:26:22 +0300
committerEric Biggers <ebiggers@google.com>2019-07-29 02:59:16 +0300
commit8a1d0f9cacc997bedc017056a94f35dc823394ed (patch)
tree90d55ad08622ed954361629d906d11469919abae /include/linux/fsverity.h
parentc1d9b584e2cf3f0562d8fcf34574c044d17853a1 (diff)
downloadlinux-8a1d0f9cacc997bedc017056a94f35dc823394ed.tar.xz
fs-verity: add data verification hooks for ->readpages()
Add functions that verify data pages that have been read from a fs-verity file, against that file's Merkle tree. These will be called from filesystems' ->readpage() and ->readpages() methods. Since data verification can block, a workqueue is provided for these methods to enqueue verification work from their bio completion callback. See the "Verifying data" section of Documentation/filesystems/fsverity.rst for more information. Reviewed-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'include/linux/fsverity.h')
-rw-r--r--include/linux/fsverity.h56
1 files changed, 56 insertions, 0 deletions
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index cbd0f84e1620..95c257cd7ff0 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -33,6 +33,23 @@ struct fsverity_operations {
*/
int (*get_verity_descriptor)(struct inode *inode, void *buf,
size_t bufsize);
+
+ /**
+ * Read a Merkle tree page of the given inode.
+ *
+ * @inode: the inode
+ * @index: 0-based index of the page within the Merkle tree
+ *
+ * This can be called at any time on an open verity file, as well as
+ * between ->begin_enable_verity() and ->end_enable_verity(). It may be
+ * called by multiple processes concurrently, even with the same page.
+ *
+ * Note that this must retrieve a *page*, not necessarily a *block*.
+ *
+ * Return: the page on success, ERR_PTR() on failure
+ */
+ struct page *(*read_merkle_tree_page)(struct inode *inode,
+ pgoff_t index);
};
#ifdef CONFIG_FS_VERITY
@@ -49,6 +66,12 @@ 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);
+/* 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);
+
#else /* !CONFIG_FS_VERITY */
static inline struct fsverity_info *fsverity_get_info(const struct inode *inode)
@@ -73,6 +96,39 @@ static inline void fsverity_cleanup_inode(struct inode *inode)
{
}
+/* verify.c */
+
+static inline bool fsverity_verify_page(struct page *page)
+{
+ WARN_ON(1);
+ return false;
+}
+
+static inline void fsverity_verify_bio(struct bio *bio)
+{
+ WARN_ON(1);
+}
+
+static inline void fsverity_enqueue_verify_work(struct work_struct *work)
+{
+ WARN_ON(1);
+}
+
#endif /* !CONFIG_FS_VERITY */
+/**
+ * fsverity_active() - do reads from the inode need to go through fs-verity?
+ *
+ * This checks whether ->i_verity_info has been set.
+ *
+ * Filesystems call this from ->readpages() 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.)
+ */
+static inline bool fsverity_active(const struct inode *inode)
+{
+ return fsverity_get_info(inode) != NULL;
+}
+
#endif /* _LINUX_FSVERITY_H */