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From: Miklos Szeredi <mszeredi@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
	lkml <linux-kernel@vger.kernel.org>,
	Linux Containers <containers@lists.linux-foundation.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Alban Crequy <alban@kinvolk.io>,
	Seth Forshee <seth.forshee@canonical.com>,
	Sargun Dhillon <sargun@sargun.me>,
	Dongsu Park <dongsu@kinvolk.io>,
	"Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: [PATCH] fuse: Ensure posix acls are translated outside of init_user_ns
Date: Tue, 29 May 2018 14:55:25 +0200	[thread overview]
Message-ID: <CAOssrKdS9gOsZrNfqJbk_j0Z8-hrqrYWW+=_Z5mUEX1KE-Kw6Q@mail.gmail.com> (raw)
In-Reply-To: <877enmskec.fsf@xmission.com>

On Tue, May 29, 2018 at 2:42 PM, Eric W. Biederman
<ebiederm@xmission.com> wrote:
> ebiederm@xmission.com (Eric W. Biederman) writes:
>
>> ebiederm@xmission.com (Eric W. Biederman) writes:
>>
>>> Ensure the translation happens by failing to read or write
>>> posix acls when the filesystem has not indicated it supports
>>> posix acls.
>>>
>>> This ensures that modern cached posix acl support is available
>>> and used when dealing with posix acls.  This is important
>>> because only that path has the code to convernt the uids and
>>> gids in posix acls into the user namespace of a fuse filesystem.
>>>
>>> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>>> ---
>>
>> ping.
>>
>> Miklos are you around where you can look at this?
>
> Perhaps I got the wrong email address.


No, sorry.  I'll queue this up for 4.18.

Just wanted to finish off overlayfs stuff before getting into fuse.

Thanks,
Miklos

>
>>
>>> Miklos after several attempts to handle this better last cycle.  I
>>> figure we should go with the stupid version for now.  I think I know
>>> how to do better but I don't want that to gate forward progress on
>>> fully unprivileged fuse mounts.  Especially as this is the last known
>>> issue to deal with.
>>>
>>>  fs/fuse/fuse_i.h |  1 +
>>>  fs/fuse/inode.c  |  7 +++++++
>>>  fs/fuse/xattr.c  | 43 +++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 51 insertions(+)
>>>
>>> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
>>> index f630951df8dc..5256ad333b05 100644
>>> --- a/fs/fuse/fuse_i.h
>>> +++ b/fs/fuse/fuse_i.h
>>> @@ -985,6 +985,7 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size);
>>>  int fuse_removexattr(struct inode *inode, const char *name);
>>>  extern const struct xattr_handler *fuse_xattr_handlers[];
>>>  extern const struct xattr_handler *fuse_acl_xattr_handlers[];
>>> +extern const struct xattr_handler *fuse_no_acl_xattr_handlers[];
>>>
>>>  struct posix_acl;
>>>  struct posix_acl *fuse_get_acl(struct inode *inode, int type);
>>> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
>>> index 1643043d4fe5..22c76cf8c2e3 100644
>>> --- a/fs/fuse/inode.c
>>> +++ b/fs/fuse/inode.c
>>> @@ -1100,6 +1100,13 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
>>>          file->f_cred->user_ns != sb->s_user_ns)
>>>              goto err_fput;
>>>
>>> +    /*
>>> +     * If we are not in the initial user namespace posix
>>> +     * acls must be translated.
>>> +     */
>>> +    if (sb->s_user_ns != &init_user_ns)
>>> +            sb->s_xattr = fuse_no_acl_xattr_handlers;
>>> +
>>>      fc = kmalloc(sizeof(*fc), GFP_KERNEL);
>>>      err = -ENOMEM;
>>>      if (!fc)
>>> diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
>>> index 3caac46b08b0..433717640f78 100644
>>> --- a/fs/fuse/xattr.c
>>> +++ b/fs/fuse/xattr.c
>>> @@ -192,6 +192,26 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
>>>      return fuse_setxattr(inode, name, value, size, flags);
>>>  }
>>>
>>> +static bool no_xattr_list(struct dentry *dentry)
>>> +{
>>> +    return false;
>>> +}
>>> +
>>> +static int no_xattr_get(const struct xattr_handler *handler,
>>> +                    struct dentry *dentry, struct inode *inode,
>>> +                    const char *name, void *value, size_t size)
>>> +{
>>> +    return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static int no_xattr_set(const struct xattr_handler *handler,
>>> +                    struct dentry *dentry, struct inode *nodee,
>>> +                    const char *name, const void *value,
>>> +                    size_t size, int flags)
>>> +{
>>> +    return -EOPNOTSUPP;
>>> +}
>>> +
>>>  static const struct xattr_handler fuse_xattr_handler = {
>>>      .prefix = "",
>>>      .get    = fuse_xattr_get,
>>> @@ -209,3 +229,26 @@ const struct xattr_handler *fuse_acl_xattr_handlers[] = {
>>>      &fuse_xattr_handler,
>>>      NULL
>>>  };
>>> +
>>> +static const struct xattr_handler fuse_no_acl_access_xattr_handler = {
>>> +    .name  = XATTR_NAME_POSIX_ACL_ACCESS,
>>> +    .flags = ACL_TYPE_ACCESS,
>>> +    .list  = no_xattr_list,
>>> +    .get   = no_xattr_get,
>>> +    .set   = no_xattr_set,
>>> +};
>>> +
>>> +static const struct xattr_handler fuse_no_acl_default_xattr_handler = {
>>> +    .name  = XATTR_NAME_POSIX_ACL_DEFAULT,
>>> +    .flags = ACL_TYPE_ACCESS,
>>> +    .list  = no_xattr_list,
>>> +    .get   = no_xattr_get,
>>> +    .set   = no_xattr_set,
>>> +};
>>> +
>>> +const struct xattr_handler *fuse_no_acl_xattr_handlers[] = {
>>> +    &fuse_no_acl_access_xattr_handler,
>>> +    &fuse_no_acl_default_xattr_handler,
>>> +    &fuse_xattr_handler,
>>> +    NULL
>>> +};

  reply	other threads:[~2018-05-29 12:55 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-04 16:47 Eric W. Biederman
2018-05-08 13:37 ` Seth Forshee
2018-05-23 16:11 ` Eric W. Biederman
2018-05-29 12:42   ` Eric W. Biederman
2018-05-29 12:55     ` Miklos Szeredi [this message]
2018-05-29 14:02       ` Eric W. Biederman
2018-05-29 14:04         ` [PATCH] fuse: Allow fully unprivileged mounts Eric W. Biederman
2018-05-31 14:45           ` Miklos Szeredi

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