Re: [PATCH] KEYS: fix length validation in keyctl_pkey_params_get_2()

[Eric Biggers <ebiggers@kernel.org>]

On Sat, Jan 15, 2022 at 11:26:16PM +0200, Jarkko Sakkinen wrote:
> On Sat, Jan 15, 2022 at 11:53:34AM -0800, Eric Biggers wrote:
> > On Sat, Jan 15, 2022 at 08:45:03PM +0200, Jarkko Sakkinen wrote:
> > > On Thu, Jan 13, 2022 at 12:04:54PM -0800, Eric Biggers wrote:
> > > > From: Eric Biggers <ebiggers@google.com>
> > > > 
> > > > In many cases, keyctl_pkey_params_get_2() is validating the user buffer
> > > > lengths against the wrong algorithm properties.  Fix it to check against
> > > > the correct properties.
> > > > 
> > > > Probably this wasn't noticed before because for all asymmetric keys of
> > > > the "public_key" subtype, max_data_size == max_sig_size == max_enc_size
> > > > == max_dec_size.  However, this isn't necessarily true for the
> > > > "asym_tpm" subtype (it should be, but it's not strictly validated).  Of
> > > > course, future key types could have different values as well.
> > > 
> > > With a quick look, asym_tpm is TPM 1.x only, which only has 2048-bit RSA
> > > keys.
> > 
> > The code allows other lengths, as well as the case where the "RSA key size"
> > doesn't match the "public key size".  Probably both are bugs and they should
> > both be 256 bytes (2048 bits) only.  Anyway, that would be a separate fix.
> > 
> > - Eric
> 
> I'm fine with the current commit message. E.g. I have no idea at this
> point whether there should be in future separate asym_tpm2 or all bundled
> to asym_tpm.
> 
> Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
> 

Okay, great.  Just to be clear, I'm expecting either you or David
(maintainer:KEYS/KEYRINGS) to apply this patch.  Acked-by is usually given by a
maintainer when someone else applies a patch.

- Eric