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Message-ID: <CAObL_7ER32AesD6bHk591ss0hTFmp0bjVOKV9oEdhiFwCEVOBA@mail.gmail.com>
Date: Thu, 12 Apr 2012 21:25:27 -0700
From: Andrew Lutomirski <luto@....edu>
To: James Morris <jmorris@...ei.org>
Cc: Will Drewry <wad@...omium.org>, linux-kernel@...r.kernel.org,
linux-man@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-arch@...r.kernel.org, linux-doc@...r.kernel.org,
kernel-hardening@...ts.openwall.com, netdev@...r.kernel.org, x86@...nel.org,
arnd@...db.de, "David S. Miller" <davem@...emloft.net>, hpa@...or.com, mingo@...hat.com,
Oleg Nesterov <oleg@...hat.com>, peterz@...radead.org, rdunlap@...otime.net,
mcgrathr@...omium.org, tglx@...utronix.de, Eric Paris <eparis@...hat.com>,
Serge Hallyn <serge.hallyn@...onical.com>, djm@...drot.org, scarybeasts@...il.com,
indan@....nu, pmoore@...hat.com, Andrew Morton <akpm@...ux-foundation.org>,
Jonathan Corbet <corbet@....net>, eric.dumazet@...il.com, markus@...omium.org,
coreyb@...ux.vnet.ibm.com, Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...capital.net>, Stephen Smalley <sds@...ho.nsa.gov>
Subject: Re: [PATCH v18 01/15] Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve
from granting privs
On Thu, Apr 12, 2012 at 9:16 PM, James Morris <jmorris@...ei.org> wrote:
> On Thu, 12 Apr 2012, Will Drewry wrote:
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index d85b793..0b06685 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -2016,6 +2016,13 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
>> new_tsec->sid = old_tsec->exec_sid;
>> /* Reset exec SID on execve. */
>> new_tsec->exec_sid = 0;
>> +
>> + /*
>> + * Minimize confusion: if no_new_privs and a transition is
>> + * explicitly requested, then fail the exec.
>> + */
>> + if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)
>> + return -EPERM;
>> } else {
>> /* Check for a default transition on this program. */
>> rc = security_transition_sid(old_tsec->sid, isec->sid,
>> @@ -2029,7 +2036,8 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
>> ad.selinux_audit_data = &sad;
>> ad.u.path = bprm->file->f_path;
>>
>> - if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
>> + if ((bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) ||
>> + (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS))
>> new_tsec->sid = old_tsec->sid;
>>
>> if (new_tsec->sid == old_tsec->sid) {
>> --
>
> What about dynamic transitions in SELinux ?
>
What's a dynamic transition?
--Andy
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