Re: [PATCH] fscrypt: to make sure the inode->i_blkbits is correctly set

[Xiubo Li]

On 1/27/24 14:37, Eric Biggers wrote:
> On Thu, Jan 25, 2024 at 12:48:25PM +0800, xiubli@xxxxxxxxxx wrote:
> > From: Xiubo Li <xiubli@xxxxxxxxxx>
> >
> > The inode->i_blkbits should be already set before calling
> > fscrypt_get_encryption_info() and it will be used this to setup the
> > ci_data_unit_bits.
> >
> > Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
> > ---
> >   fs/crypto/keysetup.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
> > index d71f7c799e79..909187e52bae 100644
> > --- a/fs/crypto/keysetup.c
> > +++ b/fs/crypto/keysetup.c
> > @@ -702,6 +702,9 @@ int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported)
> >   /**
> >    * fscrypt_prepare_new_inode() - prepare to create a new inode in a directory
> >    * @dir: a possibly-encrypted directory
> >    * @inode: the new inode.  ->i_mode must be set already.
> >    *         ->i_ino doesn't need to be set yet.
> Maybe just change the above to "->i_mode and ->i_blkbits", instead of adding a
> separate paragraph?

Just back from PTO.

Yeah, this sounds much better. I will fix it.

Thanks

- Xiubo


> >    * @encrypt_ret: (output) set to %true if the new inode will be encrypted
> >    *
> >    * If the directory is encrypted, set up its ->i_crypt_info in preparation for
> >    * encrypting the name of the new file.  Also, if the new inode will be
> >    * encrypted, set up its ->i_crypt_info and set *encrypt_ret=true.
> >    *
> >    * This isn't %GFP_NOFS-safe, and therefore it should be called before starting
> >    * any filesystem transaction to create the inode.  For this reason, ->i_ino
> >    * isn't required to be set yet, as the filesystem may not have set it yet.
> >    *
> >    * This doesn't persist the new inode's encryption context.  That still needs to
> >    * be done later by calling fscrypt_set_context().
> >    *
> > + * Please note that the inode->i_blkbits should be already set before calling
> > + * this and later it will be used to setup the ci_data_unit_bits.
> > + *
> >    * Return: 0 on success, -ENOKEY if the encryption key is missing, or another
> >    *	   -errno code
> >    */
> > @@ -717,6 +720,9 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
> >   	if (IS_ERR(policy))
> >   		return PTR_ERR(policy);
> >   
> > +	if (WARN_ON_ONCE(inode->i_blkbits == 0))
> > +		return -EINVAL;
> > +
> Thanks,
>
> - Eric