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Date: Sun, 11 Dec 2011 15:20:29 -0800 (PST)
From: Hugh Dickins <hughd@...gle.com>
To: Vasiliy Kulikov <segoon@...nwall.com>
cc: Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...iv.linux.org.uk>, Alexey Dobriyan <adobriyan@...il.com>,
kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] proc: fix task_struct infoleak
On Sun, 11 Dec 2011, Vasiliy Kulikov wrote:
> proc_pid_permission() doesn't put task_struct on every /proc/$pid/
> access. A demo from Hugh Dickins:
>
> while :; do ps; grep KernelStack /proc/meminfo; sleep 1; done
>
> Reported-by: Hugh Dickins <hughd@...gle.com>
> Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
Thank you, yes, that fixes it for me:
Tested-by: Hugh Dickins <hughd@...gle.com>
but hopefully akpm will just fold this into the original patch.
Hmm, tiny niggle, but I notice that has_pid_permissions() is
declared, reasonably, as bool; so wouldn't it be better for
has_perms to be declared as bool instead of int? Hardly
worth bothering about, but if you've a mind to respin with
a corrected Subject as Al rightly suggests.
> ---
> This is a patch against a hidepid patchset from -mm.
>
> fs/proc/base.c | 9 +++++++--
> 1 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 8caf5cb..0e5c577 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -646,9 +646,14 @@ static bool has_pid_permissions(struct pid_namespace *pid,
> static int proc_pid_permission(struct inode *inode, int mask)
> {
> struct pid_namespace *pid = inode->i_sb->s_fs_info;
> - struct task_struct *task = get_proc_task(inode);
> + struct task_struct *task;
> + int has_perms;
> +
> + task = get_proc_task(inode);
> + has_perms = has_pid_permissions(pid, task, 1);
> + put_task_struct(task);
>
> - if (!has_pid_permissions(pid, task, 1)) {
> + if (!has_perms) {
> if (pid->hide_pid == 2) {
> /*
> * Let's make getdents(), stat(), and open()
> --
> 1.7.0.4
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