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Message-ID: <559E9222.8060604@schaufler-ca.com>
Date: Thu, 09 Jul 2015 08:24:18 -0700
From: Casey Schaufler <casey@...aufler-ca.com>
To: Sergei Zviagintsev <sergei@...v.net>,
Paul Osmialowski <p.osmialowsk@...sung.com>
CC: Paul Moore <pmoore@...hat.com>,
James Morris <james.l.morris@...cle.com>,
"Serge E. Hallyn" <serge@...lyn.com>,
Kees Cook <keescook@...omium.org>,
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
Stephen Smalley <sds@...ho.nsa.gov>,
Neil Brown <neilb@...e.de>,
Mark Rustad <mark.d.rustad@...el.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Daniel Mack <daniel@...que.org>,
David Herrmann <dh.herrmann@...glemail.com>,
Djalal Harouni <tixxdz@...ndz.org>,
Shuah Khan <shuahkh@....samsung.com>,
Al Viro <viro@...iv.linux.org.uk>,
linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
Karol Lewandowski <k.lewandowsk@...sung.com>,
Lukasz Skalski <l.skalski@...sung.com>
Subject: Re: [RFC 4/8] lsm: smack: smack callbacks for kdbus security hooks
On 7/9/2015 3:08 AM, Sergei Zviagintsev wrote:
> Hi,
>
> On Wed, Jul 08, 2015 at 12:25:06PM +0200, Paul Osmialowski wrote:
>> This adds implementation of three smack callbacks sitting behind kdbus
>> security hooks as proposed by Karol Lewandowski.
>>
>> Originates from:
>>
>> git://git.infradead.org/users/pcmoore/selinux (branch: working-kdbus)
>> commit: fc3505d058c001fe72a6f66b833e0be5b2d118f3
>>
>> https://github.com/lmctl/linux.git (branch: kdbus-lsm-v4.for-systemd-v212)
>> commit: 103c26fd27d1ec8c32d85dd3d85681f936ac66fb
>>
>> Signed-off-by: Karol Lewandowski <k.lewandowsk@...sung.com>
>> Signed-off-by: Paul Osmialowski <p.osmialowsk@...sung.com>
>> ---
>> security/smack/smack_lsm.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 68 insertions(+)
>>
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index a143328..033b756 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -41,6 +41,7 @@
>> #include <linux/msg.h>
>> #include <linux/shm.h>
>> #include <linux/binfmts.h>
>> +#include <kdbus/connection.h>
>> #include "smack.h"
>>
>> #define TRANS_TRUE "TRUE"
>> @@ -3336,6 +3337,69 @@ static int smack_setprocattr(struct task_struct *p, char *name,
>> }
>>
>> /**
>> + * smack_kdbus_connect - Set the security blob for a KDBus connection
>> + * @conn: the connection
>> + * @secctx: smack label
>> + * @seclen: smack label length
>> + *
>> + * Returns 0
>> + */
>> +static int smack_kdbus_connect(struct kdbus_conn *conn,
>> + const char *secctx, u32 seclen)
>> +{
>> + struct smack_known *skp;
>> +
>> + if (secctx && seclen > 0)
>> + skp = smk_import_entry(secctx, seclen);
>> + else
>> + skp = smk_of_current();
>> + conn->security = skp;
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * smack_kdbus_conn_free - Clear the security blob for a KDBus connection
>> + * @conn: the connection
>> + *
>> + * Clears the blob pointer
>> + */
>> +static void smack_kdbus_conn_free(struct kdbus_conn *conn)
>> +{
>> + conn->security = NULL;
>> +}
>> +
>> +/**
>> + * smack_kdbus_talk - Smack access on KDBus
>> + * @src: source kdbus connection
>> + * @dst: destination kdbus connection
>> + *
>> + * Return 0 if a subject with the smack of sock could access
>> + * an object with the smack of other, otherwise an error code
>> + */
>> +static int smack_kdbus_talk(const struct kdbus_conn *src,
>> + const struct kdbus_conn *dst)
>> +{
>> + struct smk_audit_info ad;
>> + struct smack_known *sskp = src->security;
>> + struct smack_known *dskp = dst->security;
>> + int ret;
>> +
>> + BUG_ON(sskp == NULL);
>> + BUG_ON(dskp == NULL);
> I am not familiar with the smack code so far, but I see that current
> security/smack/smack_lsm.c contains only one BUG_ON and this patch adds
> another two.
Smack does not use BUG_ON for routine error checking. If there
is reason to expect that these values will not be set the case
should be checked for and handled. Otherwise, I don't believe
in cluttering the code with assertions.
>
>> +
>> + if (smack_privileged(CAP_MAC_OVERRIDE))
>> + return 0;
>> +
>> + smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_NONE);
>> +
>> + ret = smk_access(sskp, dskp, MAY_WRITE, &ad);
>> + if (ret)
>> + return ret;
>> + return 0;
> Three redundant lines here.
>
>> +}
>> +
>> +/**
>> * smack_unix_stream_connect - Smack access on UDS
>> * @sock: one sock
>> * @other: the other sock
>> @@ -4393,6 +4457,10 @@ struct security_hook_list smack_hooks[] = {
>> LSM_HOOK_INIT(inode_notifysecctx, smack_inode_notifysecctx),
>> LSM_HOOK_INIT(inode_setsecctx, smack_inode_setsecctx),
>> LSM_HOOK_INIT(inode_getsecctx, smack_inode_getsecctx),
>> +
>> + LSM_HOOK_INIT(kdbus_connect, smack_kdbus_connect),
>> + LSM_HOOK_INIT(kdbus_conn_free, smack_kdbus_conn_free),
>> + LSM_HOOK_INIT(kdbus_talk, smack_kdbus_talk),
>> };
>>
>>
>> --
>> 1.9.1
>>
>> --
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