[PATCH 01/11] fs,fsverity: reject size changes on fsverity files in setattr_prepare

Christoph Hellwig
2026-01-22T08:22:32Z

Add the check to reject truncates of fsverity files directly to
setattr_prepare instead of requiring the file system to handle it.
Besides removing boilerplate code, this also fixes the complete lack of
such check in btrfs.

Fixes: 146054090b08 ("btrfs: initial fsverity support")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/attr.c | 12 +++++++++++-
fs/ext4/inode.c | 4 ----
fs/f2fs/file.c | 4 ----
fs/verity/open.c | 8 --------
include/linux/fsverity.h | 25 -------------------------
5 files changed, 11 insertions(+), 42 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index b9ec6b47bab2..e7d7c6d19fe9 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -169,7 +169,17 @@ int setattr_prepare(struct mnt_idmap *idmap, struct dentry *dentry,
* ATTR_FORCE.
*/
if (ia_valid & ATTR_SIZE) {
- int error = inode_newsize_ok(inode, attr->ia_size);
+ int error;
+
+ /*
+ * Verity files are immutable, so deny truncates. This isn't
+ * covered by the open-time check because sys_truncate() takes a
+ * path, not an open file.
+ */
+ if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
+ return -EPERM;
+
+ error = inode_newsize_ok(inode, attr->ia_size);
if (error)
return error;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0c466ccbed69..8c2ef98fa530 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5835,10 +5835,6 @@ int ext4_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
if (error)
return error;

- error = fsverity_prepare_setattr(dentry, attr);
- if (error)
- return error;
-
if (is_quota_modification(idmap, inode, attr)) {
error = dquot_initialize(inode);
if (error)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index d7047ca6b98d..da029fed4e5a 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1074,10 +1074,6 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
if (err)
return err;

- err = fsverity_prepare_setattr(dentry, attr);
- if (err)
- return err;
-
if (unlikely(IS_IMMUTABLE(inode)))
return -EPERM;

diff --git a/fs/verity/open.c b/fs/verity/open.c
index 77b1c977af02..2aa5eae5a540 100644
--- a/fs/verity/open.c
+++ b/fs/verity/open.c
@@ -384,14 +384,6 @@ int __fsverity_file_open(struct inode *inode, struct file *filp)
}
EXPORT_SYMBOL_GPL(__fsverity_file_open);

-int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr)
-{
- if (attr->ia_valid & ATTR_SIZE)
- return -EPERM;
- return 0;
-}
-EXPORT_SYMBOL_GPL(__fsverity_prepare_setattr);
-
void __fsverity_cleanup_inode(struct inode *inode)
{
struct fsverity_info **vi_addr = fsverity_info_addr(inode);
diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h
index 5bc7280425a7..86fb1708676b 100644
--- a/include/linux/fsverity.h
+++ b/include/linux/fsverity.h
@@ -179,7 +179,6 @@ int fsverity_get_digest(struct inode *inode,
/* open.c */

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);

/**
@@ -251,12 +250,6 @@ static inline int __fsverity_file_open(struct inode *inode, struct file *filp)
return -EOPNOTSUPP;
}

-static inline int __fsverity_prepare_setattr(struct dentry *dentry,
- struct iattr *attr)
-{
- return -EOPNOTSUPP;
-}
-
static inline void fsverity_cleanup_inode(struct inode *inode)
{
}
@@ -338,22 +331,4 @@ static inline int fsverity_file_open(struct inode *inode, struct file *filp)
return 0;
}

-/**
- * fsverity_prepare_setattr() - prepare to change a verity inode's attributes
- * @dentry: dentry through which the inode is being changed
- * @attr: attributes to change
- *
- * Verity files are immutable, so deny truncates. This isn't covered by the
- * open-time check because sys_truncate() takes a path, not a file descriptor.
- *
- * Return: 0 on success, -errno on failure
- */
-static inline int fsverity_prepare_setattr(struct dentry *dentry,
- struct iattr *attr)
-{
- if (IS_VERITY(d_inode(dentry)))
- return __fsverity_prepare_setattr(dentry, attr);
- return 0;
-}
-
#endif /* _LINUX_FSVERITY_H */
--
2.47.3