[Bug libc/29771] New: Restore IPC_64 support in sysvipc *ctl functions

[Bug libc/29771] New: Restore IPC_64 support in sysvipc *ctl functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29771

            Bug ID: 29771
           Summary: Restore IPC_64 support in sysvipc *ctl functions
           Product: glibc
           Version: 2.37
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: fweimer at redhat dot com
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---
             Flags: security-

In order to call SHM_STAT_ANY kernel operations through shmctl on older glibc,
it was necessary to pass SHM_STAT_ANY | IPC_64 in the command argument,
otherwise the ipc system call would be invoked without the IPC_64 flag, giving
unexpected results on powerpc64le-linux-gnu at least.

Current glibc no longer supports that because it checks the command argument
for validity without masking the IPC_64 bit.

Patch posted:

[PATCH] Linux: Support __IPC_64 in sysvctl *ctl command arguments
<https://sourceware.org/pipermail/libc-alpha/2022-November/143343.html>

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[Bug libc/29771] Restore IPC_64 support in sysvipc *ctl functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29771

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |fweimer at redhat dot com
             Status|NEW                         |ASSIGNED
                 CC|                            |fweimer at redhat dot com

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[Bug libc/29771] Restore IPC_64 support in sysvipc *ctl functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29771

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=26637

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[Bug libc/29771] Restore IPC_64 support in sysvipc *ctl functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29771

--- Comment #1 from Florian Weimer <fweimer at redhat dot com> ---
Applications cannot simply call the underlying system call directly because
shmctl is not universally supported, and the ipc dispatcher has to be used
instead on certain kernels. I think this is an unnecessary burden on
applications, which is why I think we should keep support for the IPC_64 flag
argument.

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[Bug libc/29771] Restore IPC_64 support in sysvipc *ctl functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29771

--- Comment #2 from Florian Weimer <fweimer at redhat dot com> ---
Fixed in glibc 2.37 via:

commit 22a46dee24351fd5f4f188ad80554cad79c82524
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Nov 8 14:15:02 2022 +0100

    Linux: Support __IPC_64 in sysvctl *ctl command arguments (bug 29771)

    Old applications pass __IPC_64 as part of the command argument because
    old glibc did not check for unknown commands, and passed through the
    arguments directly to the kernel, without adding __IPC_64.
    Applications need to continue doing that for old glibc compatibility,
    so this commit enables this approach in current glibc.

    For msgctl and shmctl, if no translation is required, make
    direct system calls, as we did before the time64 changes.  If
    translation is required, mask __IPC_64 from the command argument.

    For semctl, the union-in-vararg argument handling means that
    translation is needed on all architectures.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

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[Bug libc/29771] Restore IPC_64 support in sysvipc *ctl functions

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29771

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |2.37
             Status|ASSIGNED                    |RESOLVED

--- Comment #3 from Florian Weimer <fweimer at redhat dot com> ---
Backports complete.

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