On 22/05/09 04:40PM, Eric Biggers wrote:
> A couple corrections I'll include in the next version:
Need few clarifications. Could you please help explain what am I missing here?
>
> On Sat, Apr 30, 2022 at 10:08:55PM -0700, Eric Biggers wrote:
> > + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
> > + if (fscrypt_dummy_policies_equal(&sbi->s_dummy_enc_policy,
> > + &ctx->dummy_enc_policy))
> > + return 0;
> > ext4_msg(NULL, KERN_WARNING,
> > - "Can't set test_dummy_encryption on remount");
> > + "Can't set or change test_dummy_encryption on remount");
> > return -EINVAL;
> > }
>
> I think this needs to be 'fc->purpose == FS_CONTEXT_FOR_RECONFIGURE ||
> fscrypt_is_dummy_policy_set(&sbi->s_dummy_enc_policy)', since ext4 can parse
> mount options from both s_mount_opts and the regular mount options.
Sorry, I am missing something here. Could you please help me understand why
do we need the other OR case which you mentioned above i.e.
"|| fscrypt_is_dummy_policy_set(&sbi->s_dummy_enc_policy)"
So maybe to put it this way, when will it be the case where
fscrypt_is_dummy_policy_set(&sbi->s_dummy_enc_policy) is true and it is not a
FS_CONTEXT_FOR_RECONFIGURE case?
Also just in case if I did miss something that also means the comment after this
case will not be valid anymore?
i.e.
/*
* fscrypt_add_test_dummy_key() technically changes the super_block, so
* it technically should be delayed until ext4_apply_options() like the
* other changes. But since we never get here for remounts (see above),
* and this is the last chance to report errors, we do it here.
*/
err = fscrypt_add_test_dummy_key(sb, &ctx->dummy_enc_policy);
if (err)
ext4_msg(NULL, KERN_WARNING,
"Error adding test dummy encryption key [%d]", err);
return err;
>
> > +static void ext4_apply_test_dummy_encryption(struct ext4_fs_context *ctx,
> > + struct super_block *sb)
> > +{
> > + if (!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy))
> > + return;
>
> To handle remounts correctly, this needs to be
> '!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy) ||
> fscrypt_is_dummy_policy_set(&EXT4_SB(sb)->s_dummy_enc_policy)'.
Why?
Isn't it true that in remount we should update EXT4_SB(sb)->s_dummy_enc_policy
only when ctx->dummy_enc_policy is set. If EXT4_SB(sb)->s_dummy_enc_policy is
already set and ctx->dummy_enc_policy is not set, that means it's a remount case with no mount
opts in which case ext4 should continue to have the same value of EXT4_SB(sb)->s_dummy_enc_policy?
Did I miss any case here?
-ritesh
>
> - Eric
>
>
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