From: Casey Schaufler <casey@schaufler-ca.com>
To: Paul Moore <paul@paul-moore.com>, linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org, cj.chengjian@huawei.com,
john.johansen@canonical.com
Subject: Re: [PATCH] proc: prevent changes to overridden credentials
Date: Sun, 21 Apr 2019 10:14:58 -0700 [thread overview]
Message-ID: <51d713f7-8f0d-1181-df45-0530f4c3ab0f@schaufler-ca.com> (raw)
In-Reply-To: <155570011247.27135.12509150054846153288.stgit@chester>
On 4/19/2019 11:55 AM, Paul Moore wrote:
> Prevent userspace from changing the the /proc/PID/attr values if the
> task's credentials are currently overriden. This not only makes sense
> conceptually, it also prevents some really bizarre error cases caused
> when trying to commit credentials to a task with overridden
> credentials.
>
> Cc: <stable@vger.kernel.org>
> Reported-by: "chengjian (D)" <cj.chengjian@huawei.com>
> Signed-off-by: Paul Moore <paul@paul-moore.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
> fs/proc/base.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index ddef482f1334..87ba007b86db 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2539,6 +2539,11 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
> rcu_read_unlock();
> return -EACCES;
> }
> + /* Prevent changes to overridden credentials. */
> + if (current_cred() != current_real_cred()) {
> + rcu_read_unlock();
> + return -EBUSY;
> + }
> rcu_read_unlock();
>
> if (count > PAGE_SIZE)
>
prev parent reply other threads:[~2019-04-21 17:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-19 18:55 [PATCH] proc: prevent changes to overridden credentials Paul Moore
2019-04-19 18:59 ` Paul Moore
2019-04-19 20:26 ` James Morris
2019-04-29 13:57 ` Paul Moore
2019-04-19 19:03 ` John Johansen
2019-04-21 17:14 ` Casey Schaufler [this message]
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