Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> writes: > On 5/23/24 02:05, Gabriel Krisman Bertazi wrote: >> Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> writes: >> >>> On 5/13/24 00:27, Gabriel Krisman Bertazi wrote: >>>> Eric Biggers <ebiggers@xxxxxxxxxx> writes: >>>> >>>>> On Fri, Apr 05, 2024 at 03:13:26PM +0300, Eugen Hristev wrote: >>>> >>>>>> + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) >>>>>> + return -EINVAL; >>>>>> + >>>>>> + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); >>>>>> + if (!decrypted_name.name) >>>>>> + return -ENOMEM; >>>>>> + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, >>>>>> + &decrypted_name); >>>>>> + if (res < 0) >>>>>> + goto out; >>>>> >>>>> If fscrypt_fname_disk_to_usr() returns an error and !sb_has_strict_encoding(sb), >>>>> then this function returns 0 (indicating no match) instead of the error code >>>>> (indicating an error). Is that the correct behavior? I would think that >>>>> strict_encoding should only have an effect on the actual name >>>>> comparison. >>>> >>>> No. we *want* this return code to be propagated back to f2fs. In ext4 it >>>> wouldn't matter since the error is not visible outside of ext4_match, >>>> but f2fs does the right thing and stops the lookup. >>> >>> In the previous version which I sent, you told me that the error should be >>> propagated only in strict_mode, and if !strict_mode, it should just return no match. >>> Originally I did not understand that this should be done only for utf8_strncasecmp >>> errors, and not for all the errors. I will change it here to fix that. >> >> Yes, it depends on which error we are talking about. For ENOMEM and >> whatever error fscrypt_fname_disk_to_usr returns, we surely want to send >> that back, such that f2fs can handle it (i.e abort the lookup). Unicode >> casefolding errors don't need to stop the lookup. >> >> >>>> Thinking about it, there is a second problem with this series. >>>> Currently, if we are on strict_mode, f2fs_match_ci_name does not >>>> propagate unicode errors back to f2fs. So, once a utf8 invalid sequence >>>> is found during lookup, it will be considered not-a-match but the lookup >>>> will continue. This allows some lookups to succeed even in a corrupted >>>> directory. With this patch, we will abort the lookup on the first >>>> error, breaking existing semantics. Note that these are different from >>>> memory allocation failure and fscrypt_fname_disk_to_usr. For those, it >>>> makes sense to abort. >>> >>> So , in the case of f2fs , we must not propagate utf8 errors ? It should just >>> return no match even in strict mode ? >>> If this helper is common for both f2fs and ext4, we have to do the same for ext4 ? >>> Or we are no longer able to commonize the code altogether ? >> >> We can have a common handler. It doesn't matter for Ext4 because it >> ignores all errors. Perhaps ext4 can be improved too in a different >> patchset. >> >>>> My suggestion would be to keep the current behavior. Make >>>> generic_ci_match only propagate non-unicode related errors back to the >>>> filesystem. This means that we need to move the error messages in patch >>>> 6 and 7 into this function, so they only trigger when utf8_strncasecmp* >>>> itself fails. >>>> >>> >>> So basically unicode errors stop here, and print the error message here in that case. >>> Am I understanding it correctly ? >> >> Yes, that is it. print the error message - only in strict mode - and >> return not-a-match. >> >> Is there any problem with this approach that I'm missing? > > As the printing is moved here, in the common code, we cannot use either of > f2fs_warn nor EXT4_ERROR_INODE . Any suggestion ? Would have to be something > meaningful for the user and ratelimited I guess. > Ah, that is not great, since EXT4_ERROR_INODE does more things like annotating the error in the sb and sending a FAN_FS_ERROR to any watchers. But still, this is a rare error and I'm not really sure we care, nor that it should gate the rest of the series. I'd say just use pr_err and be done with it. -- Gabriel Krisman Bertazi
