Namjae Jeon <linkinjeon@xxxxxxxxx> writes:
>> I can understand what is doing. I'm asking why there is difference.
>>
>> 1) generic_fh_to_dentry() allows (*_PARENT && fh_len == 2).
>> 2) fat_fh_to_dentry_nostale() doesn't allows (*_PARENT && fh_len == 3).
>>
>> Why does logic has difference?
>
> When we consider the generic routine of encode_fh() and the structure ‘fid’
>
> struct fid {
> struct {
> u32 ino;
> u32 gen;
> u32 parent_ino;
> u32 parent_gen;
> } i32;
> };
>
> fh_len= 2(without parent)
> fh_len=4(with parent)
>
> Condition checking in export_encode_fh()
> {
>
> if (parent && (len < 4)) {
> *max_len = 4;
> return FILEID_INVALID;
> } else if (len < 2) {
> *max_len = 2;
> return FILEID_INVALID;
> }
> ...
> len = 2;
> ...
> if (parent) {
> ..
> len = 4;
> type = FILEID_INO32_GEN_PARENT;
> }
> …
> }
>
> The logic does take care of altering the length for the ‘2’ cases
> with/without parent.
> So, while encoding -> the care has been taken for length checking but
> while decoding(generic_fh_to_dentry) the length check is not put in
> place.
> I think it should be done in the generic routine also.
>
> It should be:
> if ((fh_len != 2 && fh_len != 4) ||
> (fh_type != FILEID_INO32_GEN && fh_type !=
> FILEID_INO32_GEN_PARENT))
> return NULL;
>
> Please share your opinion.
I know encode_fh(). But NFS is network protocol, and network can input
any data, and I guess the userland interface (open_by_handle()?) can be
any too.
And generic_fh_to_dentry()'s input verify choose to check the minimum
length only. But your logic choose the exact length.
I think the both is sane and correct. But I wonder why did you changed it.
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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