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From:   Florian Weimer <fweimer@redhat.com>
To:     Stephen Smalley <sds@tycho.nsa.gov>
Cc:     apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org,
        selinux@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Security modules and sending signals within the same process
References: <87lg5asilo.fsf@oldenburg.str.redhat.com>
        <e754fa24-899b-f77e-f226-0f070ebad132@tycho.nsa.gov>
Date:   Tue, 11 Dec 2018 11:42:20 +0100
In-Reply-To: <e754fa24-899b-f77e-f226-0f070ebad132@tycho.nsa.gov> (Stephen
        Smalley's message of "Fri, 30 Nov 2018 11:02:15 -0500")
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* Stephen Smalley:

> Looks like commit 065add3941bd ("signals: check_kill_permission():
> don't check creds if same_thread_group()") skipped the uid-based
> checks if the sender and target were in the same thread group, but not
> the security hook call.  One could argue that the security hook call
> ought to be skipped in that case as well using the same rationale
> given in that commit.  Nothing appears to guarantee the property you
> state above for security_task_kill implementations, although none of
> the in-tree users are based on uids or gids so setresuid/setresgid
> shouldn't affect them.

Okay, thanks, so it looks like I don't have to do anything special to
support thread cancellation.

Florian