fsverity: add support for info in fs-specific part of inode (2a7349ad) · Commits · git / linux-net

fs/verity/enable.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -284,9 +284,9 @@ static int enable_verity(struct file *filp,
		/* Successfully enabled verity */

		/*
		* Readers can start using ->i_verity_info immediately, so it
		* can't be rolled back once set. So don't set it until just
		* after the filesystem has successfully enabled verity.
		* Readers can start using the inode's verity info immediately,
		* so it can't be rolled back once set. So don't set it until
		* just after the filesystem has successfully enabled verity.
		*/
		fsverity_set_info(inode, vi);
		}

fs/verity/fsverity_private.h

+5 −4

Original line number	Diff line number	Diff line
		@@ -63,10 +63,11 @@ struct merkle_tree_params {
		* fsverity_info - cached verity metadata for an inode
		*
		* When a verity file is first opened, an instance of this struct is allocated
		* and stored in ->i_verity_info; it remains until the inode is evicted. It
		* caches information about the Merkle tree that's needed to efficiently verify
		* data read from the file. It also caches the file digest. The Merkle tree
		* pages themselves are not cached here, but the filesystem may cache them.
		* and a pointer to it is stored in the file's in-memory inode. It remains
		* until the inode is evicted. It caches information about the Merkle tree
		* that's needed to efficiently verify data read from the file. It also caches
		* the file digest. The Merkle tree pages themselves are not cached here, but
		* the filesystem may cache them.
		*/
		struct fsverity_info {
		struct merkle_tree_params tree_params;

fs/verity/open.c

+12 −11

Original line number	Diff line number	Diff line
		@@ -244,17 +244,17 @@ struct fsverity_info fsverity_create_info(const struct inode inode,
		void fsverity_set_info(struct inode inode, struct fsverity_info vi)
		{
		/*
		* Multiple tasks may race to set ->i_verity_info, so use
		* cmpxchg_release(). This pairs with the smp_load_acquire() in
		* fsverity_get_info(). I.e., here we publish ->i_verity_info with a
		* RELEASE barrier so that other tasks can ACQUIRE it.
		* Multiple tasks may race to set the inode's verity info pointer, so
		* use cmpxchg_release(). This pairs with the smp_load_acquire() in
		* fsverity_get_info(). I.e., publish the pointer with a RELEASE
		* barrier so that other tasks can ACQUIRE it.
		*/
		if (cmpxchg_release(&inode->i_verity_info, NULL, vi) != NULL) {
		/* Lost the race, so free the fsverity_info we allocated. */
		if (cmpxchg_release(fsverity_info_addr(inode), NULL, vi) != NULL) {
		/* Lost the race, so free the verity info we allocated. */
		fsverity_free_info(vi);
		/*
		* Afterwards, the caller may access ->i_verity_info directly,
		* so make sure to ACQUIRE the winning fsverity_info.
		* Afterwards, the caller may access the inode's verity info
		* directly, so make sure to ACQUIRE the winning verity info.
		*/
		(void)fsverity_get_info(inode);
		}
		@@ -350,7 +350,6 @@ int fsverity_get_descriptor(struct inode *inode,
		return 0;
		}

		/* Ensure the inode has an ->i_verity_info */
		static int ensure_verity_info(struct inode *inode)
		{
		struct fsverity_info *vi = fsverity_get_info(inode);
		@@ -395,8 +394,10 @@ EXPORT_SYMBOL_GPL(__fsverity_prepare_setattr);

		void __fsverity_cleanup_inode(struct inode *inode)
		{
		fsverity_free_info(inode->i_verity_info);
		inode->i_verity_info = NULL;
		struct fsverity_info **vi_addr = fsverity_info_addr(inode);

		fsverity_free_info(*vi_addr);
		*vi_addr = NULL;
		}
		EXPORT_SYMBOL_GPL(__fsverity_cleanup_inode);

fs/verity/verify.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -245,7 +245,7 @@ verify_data_blocks(struct folio *data_folio, size_t len, size_t offset,
		unsigned long max_ra_pages)
		{
		struct inode *inode = data_folio->mapping->host;
		struct fsverity_info *vi = inode->i_verity_info;
		struct fsverity_info vi = fsverity_info_addr(inode);
		const unsigned int block_size = vi->tree_params.block_size;
		u64 pos = (u64)data_folio->index << PAGE_SHIFT;

include/linux/fsverity.h

+34 −10

Original line number	Diff line number	Diff line
		@@ -28,6 +28,12 @@

		/* Verity operations for filesystems */
		struct fsverity_operations {
		/**
		* The offset of the pointer to struct fsverity_info in the
		* filesystem-specific part of the inode, relative to the beginning of
		* the common part of the inode (the 'struct inode').
		*/
		ptrdiff_t inode_info_offs;

		/**
		* Begin enabling verity on the given file.
		@@ -124,15 +130,33 @@ struct fsverity_operations {

		#ifdef CONFIG_FS_VERITY

		static inline struct fsverity_info **
		fsverity_info_addr(const struct inode *inode)
		{
		if (inode->i_sb->s_vop->inode_info_offs == 0)
		return (struct fsverity_info **)&inode->i_verity_info;
		return (void *)inode + inode->i_sb->s_vop->inode_info_offs;
		}

		static inline struct fsverity_info fsverity_get_info(const struct inode inode)
		{
		/*
		* 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.
		* Since this function can be called on inodes belonging to filesystems
		* that don't support fsverity at all, and fsverity_info_addr() doesn't
		* work on such filesystems, we have to start with an IS_VERITY() check.
		* Checking IS_VERITY() here is also useful to minimize the overhead of
		* fsverity_active() on non-verity files.
		*/
		if (!IS_VERITY(inode))
		return NULL;

		/*
		* Pairs with the cmpxchg_release() in fsverity_set_info(). I.e.,
		* another task may publish the inode's verity info concurrently,
		* executing a RELEASE barrier. Use smp_load_acquire() here to safely
		* ACQUIRE the memory the other task published.
		*/
		return smp_load_acquire(&inode->i_verity_info);
		return smp_load_acquire(fsverity_info_addr(inode));
		}

		/* enable.c */
		@@ -156,11 +180,11 @@ void __fsverity_cleanup_inode(struct inode *inode);
		* fsverity_cleanup_inode() - free the inode's verity info, if present
		* @inode: an inode being evicted
		*
		* Filesystems must call this on inode eviction to free ->i_verity_info.
		* Filesystems must call this on inode eviction to free the inode's verity info.
		*/
		static inline void fsverity_cleanup_inode(struct inode *inode)
		{
		if (inode->i_verity_info)
		if (*fsverity_info_addr(inode))
		__fsverity_cleanup_inode(inode);
		}

		@@ -267,12 +291,12 @@ static inline bool fsverity_verify_page(struct page *page)
		* 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.
		* This checks whether the inode's verity info has been set.
		*
		* 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.)
		* FS_IOC_ENABLE_VERITY completing. (S_VERITY is set before the verity info.)
		*
		* Return: true if reads need to go through fs-verity, otherwise false
		*/
		@@ -287,7 +311,7 @@ static inline bool fsverity_active(const struct inode *inode)
		* @filp: the struct file being set up
		*
		* When opening a verity file, deny the open if it is for writing. Otherwise,
		* set up the inode's ->i_verity_info if not already done.
		* set up the inode's verity info if not already done.
		*
		* When combined with fscrypt, this must be called after fscrypt_file_open().
		* Otherwise, we won't have the key set up to decrypt the verity metadata.