From: Al Viro <viro@zeniv.linux.org.uk>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Wenbo Zhang <ethercflow@gmail.com>,
bpf@vger.kernel.org, ast@kernel.org.com, daniel@iogearbox.net,
yhs@fb.com, andrii.nakryiko@gmail.com, netdev@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH bpf-next v10 1/2] bpf: add new helper get_file_path for mapping a file descriptor to a pathname
Date: Sat, 23 Nov 2019 04:43:54 +0000 [thread overview]
Message-ID: <20191123044354.GG26530@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20191123031826.j2dj7mzto57ml6pr@ast-mbp.dhcp.thefacebook.com>
On Fri, Nov 22, 2019 at 07:18:28PM -0800, Alexei Starovoitov wrote:
> > + /* After filter unmountable pseudo filesytem, d_path won't call
> > + * dentry->d_op->d_name(), the normally path doesn't have any
> > + * sleepable code, and despite it uses the current macro to get
> > + * fs_struct (current->fs), we've already ensured we're in user
> > + * context, so it's ok to be here.
> > + */
> > + p = d_path(&f->f_path, dst, size);
> > + if (IS_ERR(p)) {
> > + ret = PTR_ERR(p);
> > + fput(f);
> > + goto error;
> > + }
> > +
> > + ret = strlen(p);
> > + memmove(dst, p, ret);
> > + dst[ret++] = '\0';
> > + fput(f);
> > + return ret;
> > +
> > +error:
> > + memset(dst, '0', size);
> > + return ret;
> > +}
>
> Al,
>
> could you please review about code whether it's doing enough checks to be
> called safely from preempt_disabled region?
Depends. Which context is it running in? In particular, which
locks might be already held?
next prev parent reply other threads:[~2019-11-23 4:43 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-19 13:27 [PATCH bpf-next v10 0/2] bpf: adding get_file_path helper Wenbo Zhang
2019-11-19 13:27 ` [PATCH bpf-next v10 1/2] bpf: add new helper get_file_path for mapping a file descriptor to a pathname Wenbo Zhang
2019-11-23 3:18 ` Alexei Starovoitov
2019-11-23 4:43 ` Al Viro [this message]
2019-11-23 4:51 ` Al Viro
2019-11-23 5:19 ` Alexei Starovoitov
2019-11-23 5:35 ` Al Viro
2019-11-23 6:04 ` Alexei Starovoitov
2019-12-13 19:51 ` Brendan Gregg
2019-12-05 4:20 ` [PATCH bpf-next v11 0/2] bpf: adding get_file_path helper Wenbo Zhang
2019-12-05 4:20 ` [PATCH bpf-next v11 1/2] bpf: add new helper get_file_path for mapping a file descriptor to a pathname Wenbo Zhang
2019-12-05 7:19 ` Alexei Starovoitov
2019-12-05 9:47 ` Wenbo Zhang
2019-12-15 4:01 ` [PATCH bpf-next v12 0/2] bpf: adding get_file_path helper Wenbo Zhang
2019-12-15 4:01 ` [PATCH bpf-next v12 1/2] bpf: add new helper get_file_path for mapping a file descriptor to a pathname Wenbo Zhang
2019-12-15 16:05 ` Yonghong Song
2019-12-17 6:26 ` Wenbo Zhang
2019-12-17 6:33 ` Yonghong Song
2019-12-15 16:10 ` Yonghong Song
2019-12-17 6:27 ` Wenbo Zhang
2019-12-16 22:09 ` Brendan Gregg
2019-12-17 4:05 ` Wenbo Zhang
2019-12-17 9:47 ` [PATCH bpf-next v13 0/2] bpf: adding get_fd_path helper Wenbo Zhang
2019-12-17 9:47 ` [PATCH bpf-next v13 1/2] bpf: add new helper get_fd_path for mapping a file descriptor to a pathname Wenbo Zhang
2019-12-17 16:29 ` Yonghong Song
2019-12-17 19:39 ` Daniel Borkmann
2019-12-18 0:11 ` Wenbo Zhang
2019-12-18 0:06 ` Wenbo Zhang
2019-12-18 0:56 ` [PATCH bpf-next v14 0/2] bpf: adding get_fd_path helper Wenbo Zhang
2019-12-18 0:56 ` [PATCH bpf-next v14 1/2] bpf: add new helper get_fd_path for mapping a file descriptor to a pathname Wenbo Zhang
2019-12-18 3:27 ` Yonghong Song
2019-12-19 16:14 ` Daniel Borkmann
2019-12-20 3:35 ` Wenbo Zhang
2020-01-16 8:59 ` Jiri Olsa
2020-02-10 4:43 ` Brendan Gregg
2020-02-11 0:01 ` Daniel Borkmann
2020-02-12 15:21 ` Jiri Olsa
2020-06-01 14:17 ` Wenbo Zhang
2020-06-01 16:38 ` Alexei Starovoitov
2020-06-02 3:04 ` Wenbo Zhang
2020-06-02 8:14 ` Jiri Olsa
2019-12-18 0:56 ` [PATCH bpf-next v14 2/2] selftests/bpf: test for bpf_get_fd_path() from tracepoint Wenbo Zhang
2019-12-18 3:27 ` Yonghong Song
2019-12-17 9:47 ` [PATCH bpf-next v13 " Wenbo Zhang
2019-12-17 16:32 ` Yonghong Song
2019-12-15 4:01 ` [PATCH bpf-next v12 2/2] selftests/bpf: test for bpf_get_file_path() " Wenbo Zhang
2019-12-15 16:24 ` Yonghong Song
2019-12-17 4:01 ` Wenbo Zhang
2019-12-17 4:13 ` Yonghong Song
2019-12-17 9:44 ` Wenbo Zhang
2019-12-05 4:20 ` [PATCH bpf-next v11 " Wenbo Zhang
2019-11-19 13:27 ` [PATCH bpf-next v10 " Wenbo Zhang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191123044354.GG26530@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=alexei.starovoitov@gmail.com \
--cc=andrii.nakryiko@gmail.com \
--cc=ast@kernel.org.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=ethercflow@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=yhs@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).