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| -rw-r--r-- | Documentation/filesystems/fsverity.rst | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst index 76e538217868..dacdbc1149e6 100644 --- a/Documentation/filesystems/fsverity.rst +++ b/Documentation/filesystems/fsverity.rst @@ -248,11 +248,17 @@ FS_IOC_READ_VERITY_METADATA The FS_IOC_READ_VERITY_METADATA ioctl reads verity metadata from a verity file. This ioctl is available since Linux v5.12. -This ioctl allows writing a server program that takes a verity file -and serves it to a client program, such that the client can do its own -fs-verity compatible verification of the file. This only makes sense -if the client doesn't trust the server and if the server needs to -provide the storage for the client. +This ioctl is useful for cases where the verity verification should be +performed somewhere other than the currently running kernel. + +One example is a server program that takes a verity file and serves it +to a client program, such that the client can do its own fs-verity +compatible verification of the file. This only makes sense if the +client doesn't trust the server and if the server needs to provide the +storage for the client. + +Another example is copying verity metadata when creating filesystem +images in userspace (such as with ``mkfs.ext4 -d``). This is a fairly specialized use case, and most fs-verity users won't need this ioctl. |