From: Al Viro <viro@zeniv.linux.org.uk>
To: NeilBrown <neil@brown.name>
Cc: Kees Cook <kees@kernel.org>,
Joel Granados <joel.granados@kernel.org>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] proc_sysctl: Fix up ->is_seen() handling
Date: Fri, 13 Jun 2025 02:54:21 +0100 [thread overview]
Message-ID: <20250613015421.GD1647736@ZenIV> (raw)
In-Reply-To: <174977507817.608730.3467596162021780258@noble.neil.brown.name>
On Fri, Jun 13, 2025 at 10:37:58AM +1000, NeilBrown wrote:
>
> Some sysctl tables can provide an is_seen() function which reports if
> the sysctl should be visible to the current process. This is currently
> used to cause d_compare to fail for invisible sysctls.
>
> This technique might have worked in 2.6.26 when it was implemented, but
> it cannot work now. In particular if ->d_compare always fails for a
> particular name, then d_alloc_parallel() will always create a new dentry
> and pass it to lookup() resulting in a new inode for every lookup. I
> tested this by changing sysctl_is_seen() to always return 0. When
> all sysctls were still visible and repeated lookups (ls -li) reported
> different inode numbers.
What do you mean, "name"?
next prev parent reply other threads:[~2025-06-13 1:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-13 0:37 [PATCH] proc_sysctl: Fix up ->is_seen() handling NeilBrown
2025-06-13 1:54 ` Al Viro [this message]
2025-06-13 2:01 ` Al Viro
2025-06-13 2:18 ` NeilBrown
2025-06-13 2:37 ` NeilBrown
2025-06-13 2:41 ` Al Viro
2025-06-13 3:14 ` Al Viro
2025-06-16 8:37 ` [LTP] " kernel test robot
2025-06-16 8:37 ` kernel test robot
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