From: Aleksa Sarai <asarai@suse.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Song Liu <songliubraving@fb.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Alexei Starovoitov <ast@kernel.org>,
linux-kernel@vger.kernel.org, David Howells <dhowells@redhat.com>,
linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
containers@lists.linux-foundation.org,
Christian Brauner <christian.brauner@ubuntu.com>,
linux-api@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
Tycho Andersen <tycho@tycho.ws>,
Daniel Borkmann <daniel@iogearbox.net>,
Jiri Olsa <jolsa@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
linux-arm-kernel@lists.infradead.org, Yonghong Song <yhs@fb.com>,
linux-mips@vger.kernel.org, Andrii Nakryiko <andriin@fb.com>,
bpf@vger.kernel.orgl
Subject: Re: [PATCH v16 06/12] namei: LOOKUP_NO_XDEV: block mountpoint crossing
Date: Sun, 17 Nov 2019 04:24:15 +1100 [thread overview]
Message-ID: <20191116172415.brmuonasi3ef6leg@yavin.dot.cyphar.com> (raw)
In-Reply-To: <20191116010144.GY26530@ZenIV.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1589 bytes --]
On 2019-11-16, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Sat, Nov 16, 2019 at 11:27:56AM +1100, Aleksa Sarai wrote:
>
> > @@ -1383,6 +1398,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
> > return -ECHILD;
> > if (&mparent->mnt == nd->path.mnt)
> > break;
> > + if (unlikely(nd->flags & LOOKUP_NO_XDEV))
> > + return -EXDEV;
> > /* we know that mountpoint was pinned */
> > nd->path.dentry = mountpoint;
> > nd->path.mnt = &mparent->mnt;
> > @@ -1397,6 +1414,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
> > return -ECHILD;
> > if (!mounted)
> > break;
> > + if (unlikely(nd->flags & LOOKUP_NO_XDEV))
> > + return -EXDEV;
> > nd->path.mnt = &mounted->mnt;
> > nd->path.dentry = mounted->mnt.mnt_root;
> > inode = nd->path.dentry->d_inode;
>
> I really don't think we should return hard errors from that function.
> Let the caller redo it in refwalk mode.
I suspected as much, though my reason for not changing it was that the
mount_lock check should ensure that the cached status of whether ".." is
a mountpoint crossing is correct. But I guess this is more about being
safe than sorry, rather than an actual bug?
> It's not the fast path, especially for this kind of errors. Matter of
> fact, I'm not sure about -ENOENT returned in another failure case
> there - it's probably OK, but again, -ECHILD would be just as good.
I can switch the -ENOENT too if you like.
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Aleksa Sarai <asarai@suse.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Song Liu <songliubraving@fb.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Alexei Starovoitov <ast@kernel.org>,
linux-kernel@vger.kernel.org, David Howells <dhowells@redhat.com>,
linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
containers@lists.linux-foundation.org,
Christian Brauner <christian.brauner@ubuntu.com>,
linux-api@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
Tycho Andersen <tycho@tycho.ws>,
Daniel Borkmann <daniel@iogearbox.net>,
Jiri Olsa <jolsa@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
linux-arm-kernel@lists.infradead.org, Yonghong Song <yhs@fb.com>,
linux-mips@vger.kernel.org, Andrii Nakryiko <andriin@fb.com>,
bpf@vger.kernel.org, linux-xtensa@linux-xtensa.org,
Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
Jann Horn <jannh@google.com>,
linuxppc-dev@lists.ozlabs.org, dev@opencontainers.org,
Aleksa Sarai <cyphar@cyphar.com>,
Andy Lutomirski <luto@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Namhyung Kim <namhyung@kernel.org>,
David Drysdale <drysdale@google.com>,
Christian Brauner <christian@brauner.io>,
"J. Bruce Fields" <bfields@fieldses.org>,
libc-alpha@sourceware.org, linux-parisc@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, netdev@vger.kernel.org,
Chanho Min <chanho.min@lge.com>, Jeff Layton <jlayton@kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Martin KaFai Lau <kafai@fb.com>
Subject: Re: [PATCH v16 06/12] namei: LOOKUP_NO_XDEV: block mountpoint crossing
Date: Sun, 17 Nov 2019 04:24:15 +1100 [thread overview]
Message-ID: <20191116172415.brmuonasi3ef6leg@yavin.dot.cyphar.com> (raw)
In-Reply-To: <20191116010144.GY26530@ZenIV.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1589 bytes --]
On 2019-11-16, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Sat, Nov 16, 2019 at 11:27:56AM +1100, Aleksa Sarai wrote:
>
> > @@ -1383,6 +1398,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
> > return -ECHILD;
> > if (&mparent->mnt == nd->path.mnt)
> > break;
> > + if (unlikely(nd->flags & LOOKUP_NO_XDEV))
> > + return -EXDEV;
> > /* we know that mountpoint was pinned */
> > nd->path.dentry = mountpoint;
> > nd->path.mnt = &mparent->mnt;
> > @@ -1397,6 +1414,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
> > return -ECHILD;
> > if (!mounted)
> > break;
> > + if (unlikely(nd->flags & LOOKUP_NO_XDEV))
> > + return -EXDEV;
> > nd->path.mnt = &mounted->mnt;
> > nd->path.dentry = mounted->mnt.mnt_root;
> > inode = nd->path.dentry->d_inode;
>
> I really don't think we should return hard errors from that function.
> Let the caller redo it in refwalk mode.
I suspected as much, though my reason for not changing it was that the
mount_lock check should ensure that the cached status of whether ".." is
a mountpoint crossing is correct. But I guess this is more about being
safe than sorry, rather than an actual bug?
> It's not the fast path, especially for this kind of errors. Matter of
> fact, I'm not sure about -ENOENT returned in another failure case
> there - it's probably OK, but again, -ECHILD would be just as good.
I can switch the -ENOENT too if you like.
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Aleksa Sarai <asarai@suse.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Song Liu <songliubraving@fb.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Alexei Starovoitov <ast@kernel.org>,
linux-kernel@vger.kernel.org, David Howells <dhowells@redhat.com>,
linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
containers@lists.linux-foundation.org,
Christian Brauner <christian.brauner@ubuntu.com>,
linux-api@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
Tycho Andersen <tycho@tycho.ws>,
Daniel Borkmann <daniel@iogearbox.net>,
Jiri Olsa <jolsa@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
linux-arm-kernel@lists.infradead.org, Yonghong Song <yhs@fb.com>,
linux-mips@vger.kernel.org, Andrii Nakryiko <andriin@fb.com>,
bpf@vger.kernel.org, l
Subject: Re: [PATCH v16 06/12] namei: LOOKUP_NO_XDEV: block mountpoint crossing
Date: Sun, 17 Nov 2019 04:24:15 +1100 [thread overview]
Message-ID: <20191116172415.brmuonasi3ef6leg@yavin.dot.cyphar.com> (raw)
In-Reply-To: <20191116010144.GY26530@ZenIV.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1589 bytes --]
On 2019-11-16, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Sat, Nov 16, 2019 at 11:27:56AM +1100, Aleksa Sarai wrote:
>
> > @@ -1383,6 +1398,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
> > return -ECHILD;
> > if (&mparent->mnt == nd->path.mnt)
> > break;
> > + if (unlikely(nd->flags & LOOKUP_NO_XDEV))
> > + return -EXDEV;
> > /* we know that mountpoint was pinned */
> > nd->path.dentry = mountpoint;
> > nd->path.mnt = &mparent->mnt;
> > @@ -1397,6 +1414,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
> > return -ECHILD;
> > if (!mounted)
> > break;
> > + if (unlikely(nd->flags & LOOKUP_NO_XDEV))
> > + return -EXDEV;
> > nd->path.mnt = &mounted->mnt;
> > nd->path.dentry = mounted->mnt.mnt_root;
> > inode = nd->path.dentry->d_inode;
>
> I really don't think we should return hard errors from that function.
> Let the caller redo it in refwalk mode.
I suspected as much, though my reason for not changing it was that the
mount_lock check should ensure that the cached status of whether ".." is
a mountpoint crossing is correct. But I guess this is more about being
safe than sorry, rather than an actual bug?
> It's not the fast path, especially for this kind of errors. Matter of
> fact, I'm not sure about -ENOENT returned in another failure case
> there - it's probably OK, but again, -ECHILD would be just as good.
I can switch the -ENOENT too if you like.
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
next prev parent reply other threads:[~2019-11-16 17:24 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-16 0:27 [PATCH v16 00/12] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 01/12] nsfs: clean-up ns_get_path() signature to return int Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 02/12] namei: allow nd_jump_link() to produce errors Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:37 ` Al Viro
2019-11-16 0:37 ` Al Viro
2019-11-16 0:37 ` Al Viro
2019-11-16 18:09 ` Aleksa Sarai
2019-11-16 18:09 ` Aleksa Sarai
2019-11-16 18:09 ` Aleksa Sarai
2019-11-16 18:09 ` Aleksa Sarai
2019-11-16 18:09 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 03/12] namei: allow set_root() " Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 04/12] namei: LOOKUP_NO_SYMLINKS: block symlink resolution Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 05/12] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 06/12] namei: LOOKUP_NO_XDEV: block mountpoint crossing Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 1:01 ` Al Viro
2019-11-16 1:01 ` Al Viro
2019-11-16 1:01 ` Al Viro
2019-11-16 17:24 ` Aleksa Sarai [this message]
2019-11-16 17:24 ` Aleksa Sarai
2019-11-16 17:24 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 07/12] namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 08/12] namei: LOOKUP_IN_ROOT: chroot-like " Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 09/12] namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 09/12] namei: LOOKUP_{IN_ROOT, BENEATH}: " Aleksa Sarai
2019-11-16 0:27 ` [PATCH v16 09/12] namei: LOOKUP_{IN_ROOT,BENEATH}: " Aleksa Sarai
2019-11-16 0:27 ` Aleksa Sarai
2019-11-16 1:03 ` Al Viro
2019-11-16 1:03 ` Al Viro
2019-11-16 1:03 ` Al Viro
2019-11-16 16:38 ` Aleksa Sarai
2019-11-16 16:38 ` Aleksa Sarai
2019-11-16 16:38 ` Aleksa Sarai
2019-11-16 0:28 ` [PATCH v16 10/12] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` [PATCH v16 11/12] selftests: add openat2(2) selftests Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` [PATCH v16 12/12] Documentation: path-lookup: include new LOOKUP flags Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
2019-11-16 0:28 ` Aleksa Sarai
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=20191116172415.brmuonasi3ef6leg@yavin.dot.cyphar.com \
--to=asarai@suse.de \
--cc=alexander.shishkin@linux.intel.com \
--cc=andriin@fb.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.orgl \
--cc=christian.brauner@ubuntu.com \
--cc=containers@lists.linux-foundation.org \
--cc=daniel@iogearbox.net \
--cc=dhowells@redhat.com \
--cc=jolsa@redhat.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-sh@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=shuah@kernel.org \
--cc=songliubraving@fb.com \
--cc=sparclinux@vger.kernel.org \
--cc=tycho@tycho.ws \
--cc=viro@zeniv.linux.org.uk \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.