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236 lines
6.8 KiB
236 lines
6.8 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* fs-verity: read-only file-based authenticity protection |
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* |
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* This header declares the interface between the fs/verity/ support layer and |
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* filesystems that support fs-verity. |
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* |
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* Copyright 2019 Google LLC |
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*/ |
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#ifndef _LINUX_FSVERITY_H |
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#define _LINUX_FSVERITY_H |
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#include <linux/fs.h> |
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#include <uapi/linux/fsverity.h> |
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/* Verity operations for filesystems */ |
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struct fsverity_operations { |
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/** |
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* Begin enabling verity on the given file. |
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* |
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* @filp: a readonly file descriptor for the file |
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* |
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* The filesystem must do any needed filesystem-specific preparations |
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* for enabling verity, e.g. evicting inline data. It also must return |
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* -EBUSY if verity is already being enabled on the given file. |
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* |
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* i_rwsem is held for write. |
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* |
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* Return: 0 on success, -errno on failure |
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*/ |
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int (*begin_enable_verity)(struct file *filp); |
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/** |
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* End enabling verity on the given file. |
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* |
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* @filp: a readonly file descriptor for the file |
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* @desc: the verity descriptor to write, or NULL on failure |
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* @desc_size: size of verity descriptor, or 0 on failure |
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* @merkle_tree_size: total bytes the Merkle tree took up |
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* |
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* If desc == NULL, then enabling verity failed and the filesystem only |
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* must do any necessary cleanups. Else, it must also store the given |
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* verity descriptor to a fs-specific location associated with the inode |
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* and do any fs-specific actions needed to mark the inode as a verity |
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* inode, e.g. setting a bit in the on-disk inode. The filesystem is |
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* also responsible for setting the S_VERITY flag in the VFS inode. |
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* |
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* i_rwsem is held for write, but it may have been dropped between |
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* ->begin_enable_verity() and ->end_enable_verity(). |
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* |
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* Return: 0 on success, -errno on failure |
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*/ |
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int (*end_enable_verity)(struct file *filp, const void *desc, |
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size_t desc_size, u64 merkle_tree_size); |
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/** |
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* Get the verity descriptor of the given inode. |
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* |
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* @inode: an inode with the S_VERITY flag set |
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* @buf: buffer in which to place the verity descriptor |
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* @bufsize: size of @buf, or 0 to retrieve the size only |
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* |
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* If bufsize == 0, then the size of the verity descriptor is returned. |
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* Otherwise the verity descriptor is written to 'buf' and its actual |
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* size is returned; -ERANGE is returned if it's too large. This may be |
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* called by multiple processes concurrently on the same inode. |
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* |
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* Return: the size on success, -errno on failure |
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*/ |
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int (*get_verity_descriptor)(struct inode *inode, void *buf, |
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size_t bufsize); |
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/** |
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* Read a Merkle tree page of the given inode. |
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* |
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* @inode: the inode |
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* @index: 0-based index of the page within the Merkle tree |
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* @num_ra_pages: The number of Merkle tree pages that should be |
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* prefetched starting at @index if the page at @index |
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* isn't already cached. Implementations may ignore this |
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* argument; it's only a performance optimization. |
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* |
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* This can be called at any time on an open verity file, as well as |
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* between ->begin_enable_verity() and ->end_enable_verity(). It may be |
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* called by multiple processes concurrently, even with the same page. |
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* |
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* Note that this must retrieve a *page*, not necessarily a *block*. |
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* |
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* Return: the page on success, ERR_PTR() on failure |
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*/ |
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struct page *(*read_merkle_tree_page)(struct inode *inode, |
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pgoff_t index, |
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unsigned long num_ra_pages); |
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/** |
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* Write a Merkle tree block to the given inode. |
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* |
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* @inode: the inode for which the Merkle tree is being built |
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* @buf: block to write |
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* @index: 0-based index of the block within the Merkle tree |
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* @log_blocksize: log base 2 of the Merkle tree block size |
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* |
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* This is only called between ->begin_enable_verity() and |
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* ->end_enable_verity(). |
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* |
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* Return: 0 on success, -errno on failure |
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*/ |
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int (*write_merkle_tree_block)(struct inode *inode, const void *buf, |
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u64 index, int log_blocksize); |
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}; |
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#ifdef CONFIG_FS_VERITY |
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static inline struct fsverity_info *fsverity_get_info(const struct inode *inode) |
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{ |
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/* |
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* Pairs with the cmpxchg_release() in fsverity_set_info(). |
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* I.e., another task may publish ->i_verity_info concurrently, |
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* executing a RELEASE barrier. We need to use smp_load_acquire() here |
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* to safely ACQUIRE the memory the other task published. |
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*/ |
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return smp_load_acquire(&inode->i_verity_info); |
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} |
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/* enable.c */ |
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int fsverity_ioctl_enable(struct file *filp, const void __user *arg); |
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/* measure.c */ |
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int fsverity_ioctl_measure(struct file *filp, void __user *arg); |
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/* open.c */ |
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int fsverity_file_open(struct inode *inode, struct file *filp); |
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int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr); |
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void fsverity_cleanup_inode(struct inode *inode); |
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/* read_metadata.c */ |
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int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg); |
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/* verify.c */ |
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bool fsverity_verify_page(struct page *page); |
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void fsverity_verify_bio(struct bio *bio); |
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void fsverity_enqueue_verify_work(struct work_struct *work); |
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#else /* !CONFIG_FS_VERITY */ |
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static inline struct fsverity_info *fsverity_get_info(const struct inode *inode) |
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{ |
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return NULL; |
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} |
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/* enable.c */ |
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static inline int fsverity_ioctl_enable(struct file *filp, |
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const void __user *arg) |
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{ |
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return -EOPNOTSUPP; |
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} |
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/* measure.c */ |
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static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) |
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{ |
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return -EOPNOTSUPP; |
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} |
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/* open.c */ |
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static inline int fsverity_file_open(struct inode *inode, struct file *filp) |
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{ |
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return IS_VERITY(inode) ? -EOPNOTSUPP : 0; |
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} |
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static inline int fsverity_prepare_setattr(struct dentry *dentry, |
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struct iattr *attr) |
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{ |
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return IS_VERITY(d_inode(dentry)) ? -EOPNOTSUPP : 0; |
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} |
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static inline void fsverity_cleanup_inode(struct inode *inode) |
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{ |
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} |
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/* read_metadata.c */ |
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static inline int fsverity_ioctl_read_metadata(struct file *filp, |
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const void __user *uarg) |
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{ |
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return -EOPNOTSUPP; |
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} |
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/* verify.c */ |
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static inline bool fsverity_verify_page(struct page *page) |
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{ |
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WARN_ON(1); |
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return false; |
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} |
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static inline void fsverity_verify_bio(struct bio *bio) |
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{ |
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WARN_ON(1); |
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} |
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static inline void fsverity_enqueue_verify_work(struct work_struct *work) |
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{ |
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WARN_ON(1); |
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} |
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#endif /* !CONFIG_FS_VERITY */ |
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/** |
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* fsverity_active() - do reads from the inode need to go through fs-verity? |
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* @inode: inode to check |
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* |
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* This checks whether ->i_verity_info has been set. |
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* |
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* Filesystems call this from ->readpages() to check whether the pages need to |
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* be verified or not. Don't use IS_VERITY() for this purpose; it's subject to |
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* a race condition where the file is being read concurrently with |
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* FS_IOC_ENABLE_VERITY completing. (S_VERITY is set before ->i_verity_info.) |
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* |
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* Return: true if reads need to go through fs-verity, otherwise false |
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*/ |
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static inline bool fsverity_active(const struct inode *inode) |
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{ |
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return fsverity_get_info(inode) != NULL; |
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} |
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#endif /* _LINUX_FSVERITY_H */
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