Re: [PATCH v4 05/16] fs-verity: add Kconfig and the helper functions for hashing

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Jun 06, 2019 at 08:51:54AM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
> 
> Add the beginnings of the fs/verity/ support layer, including the
> Kconfig option and various helper functions for hashing.  To start, only
> SHA-256 is supported, but other hash algorithms can easily be added.
> 
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>

Looks good; you can add:

Reviewed-off-by: Theodore Ts'o <tytso@xxxxxxx>

One thought for consideration below...


> +
> +/*
> + * Maximum depth of the Merkle tree.  Up to 64 levels are theoretically possible
> + * with a very small block size, but we'd like to limit stack usage during
> + * verification, and in practice this is plenty.  E.g., with SHA-256 and 4K
> + * blocks, a file with size UINT64_MAX bytes needs just 8 levels.
> + */
> +#define FS_VERITY_MAX_LEVELS		16

Maybe we should make FS_VERITY_MAX_LEVELS 8 for now?  This is an
implementation-level restriction, and currently we don't support any
architectures that have a page size < 4k.  We can always bump this
number up in the future if it ever becomes necessary, and limiting max
levels to 8 saves almost 100 bytes of stack space in verify_page().

						- Ted



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Linux Kernel]     [Linux Kernel Hardening]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux SCSI]

  Powered by Linux