linux-kernel - Re: [PATCH] bpf: use FS_USERNS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJqdLrrqCxt4iS4m57G6fEEOPBkXsi81hmM_sb1WgQ_96K-qKg@mail.gmail.com>
Date: Thu, 5 Feb 2026 14:57:27 +0100
From: Alexander Mikhalitsyn <alexander@...alicyn.com>
To: Daniel Borkmann <daniel@...earbox.net>
Cc: bot+bpf-ci@...nel.org, ast@...nel.org, andrii@...nel.org, 
	martin.lau@...ux.dev, eddyz87@...il.com, song@...nel.org, 
	yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org, 
	sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, jlayton@...nel.org, 
	brauner@...nel.org, bpf@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, aleksandr.mikhalitsyn@...urfusion.io, 
	martin.lau@...nel.org, clm@...a.com, ihor.solodrai@...ux.dev
Subject: Re: [PATCH] bpf: use FS_USERNS_DELEGATABLE for bpffs

Am Do., 5. Feb. 2026 um 13:49 Uhr schrieb Alexander Mikhalitsyn
<alexander@...alicyn.com>:
>
> Am Do., 5. Feb. 2026 um 13:38 Uhr schrieb Daniel Borkmann
> <daniel@...earbox.net>:
> >
> > Hi Alexander,
> >
> > On 2/5/26 12:27 PM, Alexander Mikhalitsyn wrote:
> > > Am Do., 5. Feb. 2026 um 12:20 Uhr schrieb <bot+bpf-ci@...nel.org>:
> > >>
> > >>> diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
> > >>> index 005ea3a2c..c350857b2 100644
> > >>
> > >> [ ... ]
> > >>
> > >>> @@ -1077,7 +1073,7 @@ static struct file_system_type bpf_fs_type = {
> > >>>        .init_fs_context = bpf_init_fs_context,
> > >>>        .parameters     = bpf_fs_parameters,
> > >>>        .kill_sb        = bpf_kill_super,
> > >>> -     .fs_flags       = FS_USERNS_MOUNT,
> > >>> +     .fs_flags       = FS_USERNS_DELEGATABLE,
> > >>>   };
> > >>
> > >> FS_USERNS_DELEGATABLE does not appear to be defined anywhere in the kernel
> > >> tree. A search of include/linux/fs.h shows only FS_USERNS_MOUNT is defined
> > >> (at line 2268), not FS_USERNS_DELEGATABLE.
> > >>
> > >> The commit message states this flag was "recently introduced", but it is not
> > >> present in this codebase. Will this cause a build failure due to an undefined
> > >> identifier?
> > >
> > > Yeah, this should be applied on top of
> > > https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git/commit/?h=vfs-7.0.misc&id=269c46e936f3b5f2b6b567ca124d5f5ea07a371c
> > > in vfs/vfs-7.0.misc I think.
>
> Hi Daniel,
>
> > If this goes via Christian's vfs tree, it would make sense at least to open a
> > test PR against https://github.com/kernel-patches/bpf to run this through the
> > BPF CI with the vfs branch + your patch on top to make sure the tests don't
> > break.
>
> Sure, https://github.com/kernel-patches/bpf/pull/10970#issue-3901410145

All looks good, except
x86_64 llvm-21 / test (sched_ext, false, 360) / sched_ext on x86_64 with llvm-21
which seems unrelated.

>
> Thanks for suggestion ;-)
>
> Kind regards,
> Alex
>
> >
> > Thanks,
> > Daniel