This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
- From: Aleksa Sarai <cyphar at cyphar dot com>
- To: Al Viro <viro at zeniv dot linux dot org dot uk>
- Cc: Jeff Layton <jlayton at kernel dot org>, "J. Bruce Fields" <bfields at fieldses dot org>, Arnd Bergmann <arnd at arndb dot de>, David Howells <dhowells at redhat dot com>, Shuah Khan <shuah at kernel dot org>, Shuah Khan <skhan at linuxfoundation dot org>, Ingo Molnar <mingo at redhat dot com>, Peter Zijlstra <peterz at infradead dot org>, Christian Brauner <christian dot brauner at ubuntu dot com>, Eric Biederman <ebiederm at xmission dot com>, Andy Lutomirski <luto at kernel dot org>, Andrew Morton <akpm at linux-foundation dot org>, Alexei Starovoitov <ast at kernel dot org>, Kees Cook <keescook at chromium dot org>, Jann Horn <jannh at google dot com>, Tycho Andersen <tycho at tycho dot ws>, David Drysdale <drysdale at google dot com>, Chanho Min <chanho dot min at lge dot com>, Oleg Nesterov <oleg at redhat dot com>, Rasmus Villemoes <linux at rasmusvillemoes dot dk>, Alexander Shishkin <alexander dot shishkin at linux dot intel dot com>, Jiri Olsa <jolsa at redhat dot com>, Namhyung Kim <namhyung at kernel dot org>, Christian Brauner <christian at brauner dot io>, Aleksa Sarai <asarai at suse dot de>, Linus Torvalds <torvalds at linux-foundation dot org>, containers at lists dot linux-foundation dot org, linux-alpha at vger dot kernel dot org, linux-api at vger dot kernel dot org, libc-alpha at sourceware dot org, linux-arch at vger dot kernel dot org, linux-arm-kernel at lists dot infradead dot org, linux-fsdevel at vger dot kernel dot org, linux-ia64 at vger dot kernel dot org, linux-kernel at vger dot kernel dot org, linux-kselftest at vger dot kernel dot org, linux-m68k at lists dot linux-m68k dot org, linux-mips at vger dot kernel dot org, linux-parisc at vger dot kernel dot org, linuxppc-dev at lists dot ozlabs dot org, linux-s390 at vger dot kernel dot org, linux-sh at vger dot kernel dot org, linux-xtensa at linux-xtensa dot org, sparclinux at vger dot kernel dot org
- Date: Wed, 13 Nov 2019 13:44:14 +1100
- Subject: Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
- References: <20191105090553.6350-1-cyphar@cyphar.com> <20191105090553.6350-6-cyphar@cyphar.com> <20191113020307.GB26530@ZenIV.linux.org.uk>
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/>
Attachment:
signature.asc
Description: PGP signature