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From: Al Viro <viro@zeniv.linux.org.uk>
To: Carlos Neira <cneirabustos@gmail.com>
Cc: netdev@vger.kernel.org, yhs@fb.com, ebiederm@xmission.com,
	brouer@redhat.com, bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v10 2/4] bpf: new helper to obtain namespace data from  current task New bpf helper bpf_get_current_pidns_info.
Date: Fri, 6 Sep 2019 17:00:20 +0100
Message-ID: <20190906160020.GX1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190906154647.GA19707@ZenIV.linux.org.uk>

On Fri, Sep 06, 2019 at 04:46:47PM +0100, Al Viro wrote:

> > Where do I begin?
> > 	* getname_kernel() is there for purpose
> > 	* so's kern_path(), damnit
> 
> Oh, and filename_lookup() *CAN* sleep, obviously.  So that
> GFP_ATOMIC above is completely pointless.
> 
> > > +
> > > +	inode = d_backing_inode(kp.dentry);
> > > +	pidns_info->dev = (u32)inode->i_rdev;

In the original variant of patchset it used to be ->i_sb->s_dev,
which is also bloody strange - you are not asking filename_lookup()
to follow symlinks, so you'd get that of whatever filesystem
/proc/self/ns resides on.

->i_rdev use makes no sense whatsoever - it's a symlink and
neither it nor its target are device nodes; ->i_rdev will be
left zero for both.

What data are you really trying to get there?

  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 15:09 [PATCH bpf-next v10 0/4] BPF: New helper to obtain namespace data from current task Carlos Neira
2019-09-06 15:09 ` [PATCH bpf-next v10 1/4] fs/namei.c: make available filename_lookup() for bpf helpers Carlos Neira
2019-09-06 15:09 ` [PATCH bpf-next v10 2/4] bpf: new helper to obtain namespace data from current task New bpf helper bpf_get_current_pidns_info Carlos Neira
2019-09-06 15:24   ` Al Viro
2019-09-06 15:46     ` Al Viro
2019-09-06 16:00       ` Al Viro [this message]
2019-09-06 23:21         ` Yonghong Song
2019-09-07  0:10           ` Al Viro
2019-09-07  6:34             ` Yonghong Song
2019-09-09 17:45               ` Carlos Antonio Neira Bustos
2019-09-10 22:35                 ` Yonghong Song
2019-09-10 23:15                   ` Al Viro
2019-09-11  8:16                     ` ebiederm
2019-09-12  5:49                       ` Yonghong Song
     [not found]                         ` <CACiB22j9M2gmccnh7XqqFp8g7qKFuiOrSAVJiA2tQHLB0pmoSQ@mail.gmail.com>
2019-09-13  2:56                           ` Yonghong Song
2019-09-13 11:58                             ` Carlos Antonio Neira Bustos
2019-09-13 16:59                         ` ebiederm
2019-09-13 17:28                           ` Yonghong Song
2019-09-11  4:32                   ` Carlos Antonio Neira Bustos
2019-09-11  8:17                     ` ebiederm
2019-09-10 22:46   ` Yonghong Song
2019-09-11  4:33     ` Carlos Antonio Neira Bustos
2019-09-06 15:09 ` [PATCH bpf-next v10 3/4] tools: Added bpf_get_current_pidns_info helper Carlos Neira
2019-09-06 15:09 ` [PATCH bpf-next v10 4/4] tools/testing/selftests/bpf: Add self-tests for helper bpf_get_pidns_info Carlos Neira
2019-09-10 22:55   ` Yonghong Song

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