From: Aleksa Sarai <cyphar@cyphar.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jeff Layton <jlayton@kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Arnd Bergmann <arnd@arndb.de>,
David Howells <dhowells@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
Eric Biederman <ebiederm@xmission.com>,
Andy Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
Tycho Andersen <tycho@tycho.ws>,
David Drysdale <drysdale@google.com>,
Chanho Min <chanho.min@lge.com>, Oleg Nesterov <oleg@redhat.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Christian Brauner <christian@brauner.io>,
Aleksa Sarai <asarai@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
containers@lists.linux-foundation.org,
linux-alpha@vger.kernel.org, linux-api@vger.kernel.org,
libc-alpha@sourceware.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org
Subject: Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
Date: Wed, 13 Nov 2019 13:44:14 +1100 [thread overview]
Message-ID: <20191113024414.wlmvtjstpnkxa36n@yavin.dot.cyphar.com> (raw)
Message-ID: <20191113024414.trMP_kOyOlwlBF-kJYjmGOe6KO6ATNElBO8K4yfUiQs@z> (raw)
In-Reply-To: <20191113020307.GB26530@ZenIV.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1371 bytes --]
On 2019-11-13, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Tue, Nov 05, 2019 at 08:05:49PM +1100, Aleksa Sarai wrote:
>
> > @@ -2277,12 +2277,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
> >
> > nd->m_seq = read_seqbegin(&mount_lock);
> >
> > - /* Figure out the starting path and root (if needed). */
> > - if (*s == '/') {
> > + /* Absolute pathname -- fetch the root. */
> > + if (flags & LOOKUP_IN_ROOT) {
> > + /* With LOOKUP_IN_ROOT, act as a relative path. */
> > + while (*s == '/')
> > + s++;
>
> Er... Why bother skipping slashes? I mean, not only link_path_walk()
> will skip them just fine, you are actually risking breakage in this:
> if (*s && unlikely(!d_can_lookup(dentry))) {
> fdput(f);
> return ERR_PTR(-ENOTDIR);
> }
> which is downstream from there with you patch, AFAICS.
I switched to stripping the slashes at your suggestion a few revisions
ago[1], and had (wrongly) assumed we needed to handle "/" somehow in
path_init(). But you're quite right about link_path_walk() -- and I'd be
more than happy to drop it.
[1]: https://lore.kernel.org/lkml/20190712125552.GL17978@ZenIV.linux.org.uk/
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
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next prev parent reply other threads:[~2019-11-13 2:44 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 9:05 [PATCH v15 0/9] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 1/9] namei: LOOKUP_NO_SYMLINKS: block symlink resolution Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 2/9] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution Aleksa Sarai
2019-11-13 1:24 ` Al Viro
2019-11-13 1:24 ` Al Viro
2019-11-05 9:05 ` [PATCH v15 3/9] namei: LOOKUP_NO_XDEV: block mountpoint crossing Aleksa Sarai
2019-11-13 1:36 ` Al Viro
2019-11-13 1:36 ` Al Viro
2019-11-14 4:49 ` Aleksa Sarai
2019-11-14 4:49 ` Aleksa Sarai
2019-11-14 5:43 ` Al Viro
2019-11-14 5:43 ` Al Viro
2019-11-14 13:33 ` Aleksa Sarai
2019-11-14 13:33 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 4/9] namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution Aleksa Sarai
2019-11-13 1:55 ` Al Viro
2019-11-13 1:55 ` Al Viro
2019-11-13 7:47 ` Aleksa Sarai
2019-11-13 7:47 ` Aleksa Sarai
2019-11-14 4:57 ` Aleksa Sarai
2019-11-14 4:57 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like " Aleksa Sarai
2019-11-13 2:03 ` Al Viro
2019-11-13 2:03 ` Al Viro
2019-11-13 2:44 ` Aleksa Sarai [this message]
2019-11-13 2:44 ` Aleksa Sarai
2019-11-13 2:59 ` Al Viro
2019-11-13 2:59 ` Al Viro
2019-11-13 3:55 ` Aleksa Sarai
2019-11-13 3:55 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 6/9] namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution Aleksa Sarai
2019-11-13 2:09 ` Al Viro
2019-11-13 2:09 ` Al Viro
2019-11-13 7:52 ` Aleksa Sarai
2019-11-13 7:52 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 7/9] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-13 2:29 ` Al Viro
2019-11-13 2:29 ` Al Viro
2019-11-13 2:35 ` Aleksa Sarai
2019-11-13 2:35 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 8/9] selftests: add openat2(2) selftests Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 9/9] Documentation: path-lookup: mention LOOKUP_MAGICLINK_JUMPED Aleksa Sarai
2019-11-11 13:24 ` [PATCH v15 0/9] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-12 23:01 ` Kees Cook
2019-11-12 23:01 ` Kees Cook
2019-11-12 23:06 ` Christian Brauner
2019-11-12 23:06 ` Christian Brauner
2019-11-13 0:46 ` Aleksa Sarai
2019-11-13 0:46 ` Aleksa Sarai
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