From 55eed69cc8fd88272860b3409ac83e191330d370 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 23 Dec 2022 12:36:31 -0800 Subject: [PATCH] fsverity: use EFBIG for file too large to enable verity Currently, there is an implementation limit where files can't have more than 8 Merkle tree levels. With SHA-256 and 4K blocks, this limit is never reached, since a file would need to be larger than 2**64 bytes to need 9 levels. However, with SHA-512, 9 levels are needed for files larger than about 1.15 EB, which is possible on btrfs. Therefore, this limit technically became reachable when btrfs added fsverity support. Meanwhile, support for merkle_tree_block_size < PAGE_SIZE will introduce another implementation limit on file size, resulting from the use of an in-memory bitmap to track which Merkle tree blocks have been verified. In any case, currently FS_IOC_ENABLE_VERITY fails with EINVAL when the file is too large. This is undocumented, and also ambiguous since EINVAL can mean other things too. Let's change the error code to EFBIG, which is much clearer, and document it. Signed-off-by: Eric Biggers Reviewed-by: Andrey Albershteyn Tested-by: Ojaswin Mujoo Link: https://lore.kernel.org/r/20221223203638.41293-5-ebiggers@kernel.org --- Documentation/filesystems/fsverity.rst | 1 + fs/verity/open.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst index cb8e757..66cdca3 100644 --- a/Documentation/filesystems/fsverity.rst +++ b/Documentation/filesystems/fsverity.rst @@ -161,6 +161,7 @@ FS_IOC_ENABLE_VERITY can fail with the following errors: - ``EBUSY``: this ioctl is already running on the file - ``EEXIST``: the file already has verity enabled - ``EFAULT``: the caller provided inaccessible memory +- ``EFBIG``: the file is too large to enable verity on - ``EINTR``: the operation was interrupted by a fatal signal - ``EINVAL``: unsupported version, hash algorithm, or block size; or reserved bits are set; or the file descriptor refers to neither a diff --git a/fs/verity/open.c b/fs/verity/open.c index ca8de73..09512da 100644 --- a/fs/verity/open.c +++ b/fs/verity/open.c @@ -92,7 +92,7 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, while (blocks > 1) { if (params->num_levels >= FS_VERITY_MAX_LEVELS) { fsverity_err(inode, "Too many levels in Merkle tree"); - err = -EINVAL; + err = -EFBIG; goto out_err; } blocks = (blocks + params->hashes_per_block - 1) >> -- 2.7.4