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fsverity: optimize fsverity_prepare_setattr() on non-verity files 

Make fsverity_prepare_setattr() an inline function that does the
IS_VERITY() check, then (if needed) calls __fsverity_prepare_setattr()
to do the real work.  This reduces the overhead on non-verity files.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20221214224304.145712-3-ebiggers@kernel.org
This commit is contained in:
Eric Biggers 2022-12-14 14:43:02 -08:00
parent a6528a960b
commit 01d90c07a5
2 changed files with 25 additions and 17 deletions
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16
fs/verity/open.c
View File

@ -337,26 +337,16 @@ int __fsverity_file_open(struct inode *inode, struct file *filp)
}
EXPORT_SYMBOL_GPL(__fsverity_file_open);
/**
* 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
*/
int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr)
int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr)
{
if (IS_VERITY(d_inode(dentry)) && (attr->ia_valid & ATTR_SIZE)) {
if (attr->ia_valid & ATTR_SIZE) {
pr_debug("Denying truncate of verity file (ino %lu)\n",
d_inode(dentry)->i_ino);
return -EPERM;
}
return 0;
}
EXPORT_SYMBOL_GPL(fsverity_prepare_setattr);
EXPORT_SYMBOL_GPL(__fsverity_prepare_setattr);
/**
* fsverity_cleanup_inode() - free the inode's verity info, if present

26
include/linux/fsverity.h
View File

@ -149,7 +149,7 @@ 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);
int __fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr);
void fsverity_cleanup_inode(struct inode *inode);
/* read_metadata.c */
@ -198,10 +198,10 @@ 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)
static inline int __fsverity_prepare_setattr(struct dentry *dentry,
struct iattr *attr)
{
return IS_VERITY(d_inode(dentry)) ? -EOPNOTSUPP : 0;
return -EOPNOTSUPP;
}
static inline void fsverity_cleanup_inode(struct inode *inode)
@ -274,4 +274,22 @@ 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 */