From: "H.J. Lu" <hjl.tools@gmail.com>
To: "Carlos O'Donell" <carlos@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>
Subject: Re: V2 [PATCH] nptl: Zero-extend arguments to SETXID syscalls [BZ #26248]
Date: Fri, 17 Jul 2020 15:31:33 -0700 [thread overview]
Message-ID: <CAMe9rOoYygdrsUShM_vDE+=Rn0UyuMPHy_QX6HaSTHFkXSHoLA@mail.gmail.com> (raw)
In-Reply-To: <20200717222735.GD8268@aurel32.net>
On Fri, Jul 17, 2020 at 3:27 PM Aurelien Jarno <aurelien@aurel32.net> wrote:
>
> On 2020-07-17 12:42, H.J. Lu via Libc-alpha wrote:
> > On Fri, Jul 17, 2020 at 8:02 AM Carlos O'Donell <carlos@redhat.com> wrote:
> > >
> > > On 7/16/20 8:46 AM, H.J. Lu via Libc-alpha wrote:
> > > > On Thu, Jul 16, 2020 at 5:03 AM Florian Weimer <fweimer@redhat.com> wrote:
> > > >>
> > > >> * H. J. Lu via Libc-alpha:
> > > >>
> > > >>> nptl has
> > > >>>
> > > >>> /* Opcodes and data types for communication with the signal handler to
> > > >>> change user/group IDs. */
> > > >>> struct xid_command
> > > >>> {
> > > >>> int syscall_no;
> > > >>> long int id[3];
> > > >>> volatile int cntr;
> > > >>> volatile int error;
> > > >>> };
> > > >>>
> > > >>> /* This must be last, otherwise the current thread might not have
> > > >>> permissions to send SIGSETXID syscall to the other threads. */
> > > >>> result = INTERNAL_SYSCALL_NCS (cmdp->syscall_no, 3,
> > > >>> cmdp->id[0], cmdp->id[1], cmdp->id[2]);
> > > >>>
> > > >>> But the second argument of setgroups syscal is a pointer:
> > > >>>
> > > >>> int setgroups(size_t size, const gid_t *list);
> > > >>>
> > > >>> But on x32, pointers passed to syscall must have pointer type so that they
> > > >>> will be zero-extended.
> > > >>>
> > > >>> Add <setxid-internal.h> to define INTERNAL_SETXID_SYSCALL_NCS and use it,
> > > >>> instead of INTERNAL_SYSCALL_NCS, for SETXID syscalls. X32 override it
> > > >>> with pointer type for setgroups. A testcase is added and setgroups
> > > >>> returned with EFAULT when running as root without the fix.
> > > >>
> > > >> Isn't it sufficient to change the type of id to unsigned long int[3]?
> > > >> The UID arguments are unsigned on the kernel side, so no sign extension
> > > >> is required.
> > > >>
> > > >
> > > > It works. Here is the updated patch. OK for master?
> > > >
> > > > Thanks.
> > > >
> > >
> > > This test should run in a container, and it should attempt two setgroups
> > > calls, one with groups and one empty with a bad address.
> >
> > Fixed.
> >
> > > > From 2af9e56c2306dc9d80a4476fa5b154a26a935557 Mon Sep 17 00:00:00 2001
> > > > From: "H.J. Lu" <hjl.tools@gmail.com>
> > > > Date: Thu, 16 Jul 2020 03:37:10 -0700
> > > > Subject: [PATCH] nptl: Zero-extend arguments to SETXID syscalls [BZ #26248]
> > > >
> > > > nptl has
> > > >
> > > > /* Opcodes and data types for communication with the signal handler to
> > > > change user/group IDs. */
> > > > struct xid_command
> > > > {
> > > > int syscall_no;
> > > > long int id[3];
> > > > volatile int cntr;
> > > > volatile int error;
> > > > };
> > > >
> > > > /* This must be last, otherwise the current thread might not have
> > > > permissions to send SIGSETXID syscall to the other threads. */
> > > > result = INTERNAL_SYSCALL_NCS (cmdp->syscall_no, 3,
> > > > cmdp->id[0], cmdp->id[1], cmdp->id[2]);
> > > >
> > > > But the second argument of setgroups syscal is a pointer:
> > > >
> > > > int setgroups(size_t size, const gid_t *list);
> > > >
> > > > But on x32, pointers passed to syscall must have pointer type so that they
> > > > will be zero-extended. Since the XID arguments are unsigned on the kernel
> > > > side, so no sign extension is required. Change xid_command to
> > > >
> > > > struct xid_command
> > > > {
> > > > int syscall_no;
> > > > unsigned long int id[3];
> > > > volatile int cntr;
> > > > volatile int error;
> > > > };
> > > >
> > > > so that all arguments zero-extended. A testcase is added for x32 and
> > > > setgroups returned with EFAULT when running as root without the fix.
> > > > ---
> > > > nptl/descr.h | 8 ++-
> > > > sysdeps/unix/sysv/linux/x86_64/x32/Makefile | 4 ++
> > > > .../sysv/linux/x86_64/x32/tst-setgroups.c | 67 +++++++++++++++++++
> > > > 3 files changed, 78 insertions(+), 1 deletion(-)
> > > > create mode 100644 sysdeps/unix/sysv/linux/x86_64/x32/tst-setgroups.c
>
> Is there a reason to limit that test to x32? We do not have any other
> getgroups or setgroups test in the GLIBC tree, so that simple test might
> already be able to catch issues. In addition such a test would benefit
> the other ILP32 architectures supported by GLIBC.
>
I can move it to nptl.
--
H.J.
prev parent reply other threads:[~2020-07-17 22:32 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 11:26 [PATCH] nptl: Properly inline setgroups syscall " H.J. Lu
2020-07-16 12:03 ` Florian Weimer
2020-07-16 12:46 ` [PATCH] nptl: Zero-extend arguments to SETXID syscalls " H.J. Lu
2020-07-16 15:57 ` Florian Weimer
2020-07-16 16:00 ` H.J. Lu
2020-07-16 19:38 ` Aurelien Jarno
2020-07-16 19:45 ` Aurelien Jarno
2020-07-16 21:42 ` H.J. Lu
2020-07-17 2:14 ` Carlos O'Donell
2020-07-17 2:46 ` H.J. Lu
2020-07-17 15:01 ` Carlos O'Donell
2020-07-17 15:13 ` Florian Weimer
2020-07-17 15:52 ` Carlos O'Donell
2020-07-17 19:31 ` H.J. Lu
2020-07-17 21:22 ` Carlos O'Donell
2020-07-23 20:03 ` H.J. Lu
2020-07-23 21:11 ` Carlos O'Donell
2020-07-23 21:17 ` Adhemerval Zanella
2020-07-23 21:20 ` Carlos O'Donell
2020-07-27 3:37 ` Carlos O'Donell
2020-07-27 6:00 ` Florian Weimer
2020-07-27 11:55 ` H.J. Lu
2020-07-27 12:20 ` Florian Weimer
2020-07-27 14:29 ` V3 " H.J. Lu
2020-07-27 15:49 ` Florian Weimer
2020-07-27 19:17 ` H.J. Lu
2020-07-20 11:38 ` Florian Weimer
2020-07-17 19:42 ` V2 " H.J. Lu
2020-07-17 22:27 ` Aurelien Jarno
2020-07-17 22:31 ` H.J. Lu [this message]
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='CAMe9rOoYygdrsUShM_vDE+=Rn0UyuMPHy_QX6HaSTHFkXSHoLA@mail.gmail.com' \
--to=hjl.tools@gmail.com \
--cc=carlos@redhat.com \
--cc=fweimer@redhat.com \
--cc=libc-alpha@sourceware.org \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).