Re: [RFC PATCH v3 3/5] UBIFS: ACL: handle ACL through xattr

[Dongsheng Yang <yangds.fnst@cn.fujitsu.com>]

On 09/11/2015 02:18 PM, Sheng Yong wrote:
> Hi, Dongsheng
>
> On 9/11/2015 1:01 PM, Dongsheng Yang wrote:
>> On 09/11/2015 05:09 PM, Sheng Yong wrote:
> [...]
>>
>> Why move it? If you just want to use them before the definitions,
>> Just declare them before using.
>
> OK.
>>>    int ubifs_do_setxattr(struct inode *host, const char *name,
>>>                  const void *value, size_t size, int flags)
>>>    {
>>> @@ -348,7 +462,19 @@ int ubifs_do_setxattr(struct inode *host, const char *name,
>>>            goto out_free;
>>>        }
>>>
>>> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
>>> +    if (size == 0) {
>>> +        ubifs_assert(inode->i_nlink == 1);
>>> +        clear_nlink(inode);
>>> +        err = remove_xattr(c, host, inode, &nm);
>>> +        if (err)
>>> +            set_nlink(inode, 1);
>>> +        iput(inode);
>>> +        goto out_free;
>>> +    }
>>> +#endif
>>
>> Is there a testcase for it?
>
> I test `setfacl -b/-k'. I don't know how setfacl is implemented. But for ACL_TYPE_ACCESS,
> ubifs_setxattr() is called with size = 0 and value = NULL; while for ACL_TYPE_DEFAULT,
> ubifs_removexattr() is called.

I mean, if we don't add the code above, what kind of problem
we would meet?
>
>>>        err = change_xattr(c, host, inode, value, size);
>>> +
>>>        iput(inode);
>>>
>>>    out_free:
>>> @@ -359,6 +485,9 @@ out_free:
>>>    int ubifs_setxattr(struct dentry *dentry, const char *name,
>>>               const void *value, size_t size, int flags)
>>>    {
>>> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
>>> +    const struct xattr_handler *handler;
>>> +#endif
>>>        struct qstr nm = QSTR_INIT(name, strlen(name));
>>>        int type;
>>>
>>> @@ -369,6 +498,16 @@ int ubifs_setxattr(struct dentry *dentry, const char *name,
>>>        if (type < 0)
>>>            return type;
>>>
>>> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
>>> +    if (type == POSIX_ACL_DEFAULT || type == POSIX_ACL_ACCESS) {
>>> +        if (type == POSIX_ACL_DEFAULT)
>>> +            handler = &posix_acl_default_xattr_handler;
>>> +        if (type == POSIX_ACL_ACCESS)
>>> +            handler = &posix_acl_access_xattr_handler;
>>> +        return handler->set(dentry, name, value, size, flags,
>>> +                    handler->flags);
>>> +    }
>>> +#endif
>>
>> What about setting sb->s_xattr and calling generic_setxattr() here?
>
> I have no idea if we should do this :(
> If we do, I think, we should call generic functions for all xattr.

No, only for POSIX_ACL_DEFAULT|POSIX_ACL_ACCESS currently. Then
Something like that:

if (type == POSIX_ACL_DEFAULT || type == POSIX_ACL_ACCESS)
	return generic_setxattr(dentry, name, value, size, flags);

Yang
>
> thanks,
> Sheng
>
>>>        return ubifs_do_setxattr(d_inode(dentry), name, value, size, flags);
>>>    }
>>>
>>> @@ -428,6 +567,9 @@ out_unlock:
>>>    ssize_t ubifs_getxattr(struct dentry *dentry, const char *name,
>>>                   void *value, size_t size)
>>>    {
>>> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
>>> +    const struct xattr_handler *handler;
>>> +#endif
>>>        struct qstr nm = QSTR_INIT(name, strlen(name));
>>>        int type;
>>>
>>> @@ -438,6 +580,16 @@ ssize_t ubifs_getxattr(struct dentry *dentry, const char *name,
>>>        if (type < 0)
>>>            return type;
>>>
>>> +#ifdef CONFIG_UBIFS_FS_POSIX_ACL
>>> +    if (type == POSIX_ACL_DEFAULT || type == POSIX_ACL_ACCESS) {
>>> +        if (type == POSIX_ACL_DEFAULT)
>>> +            handler = &posix_acl_default_xattr_handler;
>>> +        if (type == POSIX_ACL_ACCESS)
>>> +            handler = &posix_acl_access_xattr_handler;
>>> +        return handler->get(dentry, name, value, size,
>>> +                    handler->flags);
>>> +    }
>>> +#endif
>>
>> Ditto
>>
>> Thanx
>> Yang
>>>        return ubifs_do_getxattr(d_inode(dentry), name, value, size);
>>>    }
>>>
>>> @@ -505,95 +657,6 @@ ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
>>>        return written;
>>>    }
>>>
>>> -static int remove_xattr(struct ubifs_info *c, struct inode *host,
>>> -            struct inode *inode, const struct qstr *nm)
>>> -{
>>> -    int err;
>>> -    struct ubifs_inode *host_ui = ubifs_inode(host);
>>> -    struct ubifs_inode *ui = ubifs_inode(inode);
>>> -    struct ubifs_budget_req req = { .dirtied_ino = 2, .mod_dent = 1,
>>> -                .dirtied_ino_d = ALIGN(host_ui->data_len, 8) };
>>> -
>>> -    ubifs_assert(ui->data_len == inode->i_size);
>>> -
>>> -    err = ubifs_budget_space(c, &req);
>>> -    if (err)
>>> -        return err;
>>> -
>>> -    mutex_lock(&host_ui->ui_mutex);
>>> -    host->i_ctime = ubifs_current_time(host);
>>> -    host_ui->xattr_cnt -= 1;
>>> -    host_ui->xattr_size -= CALC_DENT_SIZE(nm->len);
>>> -    host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
>>> -    host_ui->xattr_names -= nm->len;
>>> -
>>> -    err = ubifs_jnl_delete_xattr(c, host, inode, nm);
>>> -    if (err)
>>> -        goto out_cancel;
>>> -    mutex_unlock(&host_ui->ui_mutex);
>>> -
>>> -    ubifs_release_budget(c, &req);
>>> -    return 0;
>>> -
>>> -out_cancel:
>>> -    host_ui->xattr_cnt += 1;
>>> -    host_ui->xattr_size += CALC_DENT_SIZE(nm->len);
>>> -    host_ui->xattr_size += CALC_XATTR_BYTES(ui->data_len);
>>> -    mutex_unlock(&host_ui->ui_mutex);
>>> -    ubifs_release_budget(c, &req);
>>> -    make_bad_inode(inode);
>>> -    return err;
>>> -}
>>> -
>>> -int ubifs_removexattr(struct dentry *dentry, const char *name)
>>> -{
>>> -    struct inode *inode, *host = d_inode(dentry);
>>> -    struct ubifs_info *c = host->i_sb->s_fs_info;
>>> -    struct qstr nm = QSTR_INIT(name, strlen(name));
>>> -    struct ubifs_dent_node *xent;
>>> -    union ubifs_key key;
>>> -    int err;
>>> -
>>> -    dbg_gen("xattr '%s', ino %lu ('%pd')", name,
>>> -        host->i_ino, dentry);
>>> -    ubifs_assert(mutex_is_locked(&host->i_mutex));
>>> -
>>> -    err = check_namespace(&nm);
>>> -    if (err < 0)
>>> -        return err;
>>> -
>>> -    xent = kmalloc(UBIFS_MAX_XENT_NODE_SZ, GFP_NOFS);
>>> -    if (!xent)
>>> -        return -ENOMEM;
>>> -
>>> -    xent_key_init(c, &key, host->i_ino, &nm);
>>> -    err = ubifs_tnc_lookup_nm(c, &key, xent, &nm);
>>> -    if (err) {
>>> -        if (err == -ENOENT)
>>> -            err = -ENODATA;
>>> -        goto out_free;
>>> -    }
>>> -
>>> -    inode = iget_xattr(c, le64_to_cpu(xent->inum));
>>> -    if (IS_ERR(inode)) {
>>> -        err = PTR_ERR(inode);
>>> -        goto out_free;
>>> -    }
>>> -
>>> -    ubifs_assert(inode->i_nlink == 1);
>>> -    clear_nlink(inode);
>>> -    err = remove_xattr(c, host, inode, &nm);
>>> -    if (err)
>>> -        set_nlink(inode, 1);
>>> -
>>> -    /* If @i_nlink is 0, 'iput()' will delete the inode */
>>> -    iput(inode);
>>> -
>>> -out_free:
>>> -    kfree(xent);
>>> -    return err;
>>> -}
>>> -
>>>    static size_t security_listxattr(struct dentry *d, char *list, size_t list_size,
>>>                     const char *name, size_t name_len, int flags)
>>>    {
>>>
>>
>>
>> .
>>
>
> .
>