From: Casey Schaufler <casey@schaufler-ca.com>
To: Simon McVittie <smcv@collabora.com>
Cc: casey.schaufler@intel.com, jmorris@namei.org,
linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
keescook@chromium.org, john.johansen@canonical.com,
penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com,
sds@tycho.nsa.gov, casey@schaufler-ca.com
Subject: Re: [PATCH 25/27] NET: Add SO_PEERCONTEXT for multiple LSMs
Date: Mon, 29 Jul 2019 08:04:11 -0700 [thread overview]
Message-ID: <53d9e69b-c0f9-aadf-43d1-72167e9876cc@schaufler-ca.com> (raw)
In-Reply-To: <20190729130033.GD2383@horizon>
On 7/29/2019 6:00 AM, Simon McVittie wrote:
> On Fri, 26 Jul 2019 at 16:39:21 -0700, Casey Schaufler wrote:
>> A new option SO_PEERCONTEXT is added to report the
>> security "context" of multiple modules using a "compound" format
>>
>> lsm1\0value\0lsm2\0value\0
>> + /*
>> + * A compound context, in the form lsm='value'[,lsm='value']...
>> + */
> Presumably the commit message (and the implementation) means the comment
> is out of date?
Yup. The curse of incremental development.
>> + /*
>> + * Don't propogate trailing nul bytes.
>> + */
>> + clen = strnlen(cp, clen) + 1;
>> + tlen = llen + clen;
> ...
>> + memcpy(tp + finallen + llen, cp, clen);
> This assumes that cp points to a '\0'-terminated string, with the '\0'
> either inside the span of memory cp[clen]..cp[clen-1], or at cp[clen]
> (which is just outside the range that is obviously safe to access).
> Is that assumption robust?
James Morris, the security subsystem maintainer, says:
"Security labels are strings, so this is implied."
> If an LSM that worked with length-counted
> ("Pascal") strings internally would be allowed to fill the buffer with
> nonzero bytes and not place a '\0' immediately after it, then it would
> be necessary to insert the NUL explicitly:
True enough. I could use an embedded length format:
[<lsmname\0><valuesize-u16><value>]...
but as James is willing to assert that security labels are strings
I don't think we need to go that far.
>
> clen = strnlen(cp, clen);
> tlen = llen + clen + 1;
> ...
> memcpy(tp + finallen + llen, cp, clen);
> tp[finallen + llen + clen] = '\0';
>
> Thanks,
> smcv
next prev parent reply other threads:[~2019-07-29 15:04 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 23:38 [PATCH v5 00/27] LSM: Module stacking for AppArmor Casey Schaufler
2019-07-26 23:38 ` [PATCH 01/27] LSM: Infrastructure management of the sock security Casey Schaufler
2019-07-26 23:38 ` [PATCH 02/27] LSM: Infrastructure management of the key blob Casey Schaufler
2019-07-26 23:38 ` [PATCH 03/27] LSM: Create and manage the lsmblob data structure Casey Schaufler
2019-07-26 23:39 ` [PATCH 04/27] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2019-07-26 23:39 ` [PATCH 05/27] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2019-07-26 23:39 ` [PATCH 06/27] net: Prepare UDS for security module stacking Casey Schaufler
2019-07-26 23:39 ` [PATCH 07/27] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2019-07-26 23:39 ` [PATCH 08/27] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2019-07-26 23:39 ` [PATCH 09/27] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2019-07-26 23:39 ` [PATCH 10/27] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2019-07-26 23:39 ` [PATCH 11/27] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2019-07-26 23:39 ` [PATCH 12/27] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2019-07-26 23:39 ` [PATCH 13/27] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2019-07-26 23:39 ` [PATCH 14/27] LSM: Specify which LSM to display Casey Schaufler
2019-07-29 17:05 ` Kees Cook
2019-07-26 23:39 ` [PATCH 15/27] LSM: Ensure the correct LSM context releaser Casey Schaufler
2019-07-26 23:39 ` [PATCH 16/27] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2019-07-26 23:39 ` [PATCH 17/27] LSM: Use lsmcontext in security_dentry_init_security Casey Schaufler
2019-07-26 23:39 ` [PATCH 18/27] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2019-07-26 23:39 ` [PATCH 19/27] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2019-07-26 23:39 ` [PATCH 20/27] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2019-07-26 23:39 ` [PATCH 21/27] SELinux: Verify LSM display sanity in binder Casey Schaufler
2019-07-26 23:39 ` [PATCH 22/27] Audit: Add subj_LSM fields when necessary Casey Schaufler
2019-07-26 23:39 ` [PATCH 23/27] Audit: Include object data for all security modules Casey Schaufler
2019-07-26 23:39 ` [PATCH 24/27] LSM: Provide an user space interface for the default display Casey Schaufler
2019-07-29 17:15 ` Kees Cook
2019-07-26 23:39 ` [PATCH 25/27] NET: Add SO_PEERCONTEXT for multiple LSMs Casey Schaufler
2019-07-29 13:00 ` Simon McVittie
2019-07-29 15:04 ` Casey Schaufler [this message]
2019-07-26 23:39 ` [PATCH 26/27] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2019-07-29 17:19 ` Kees Cook
2019-07-29 19:22 ` Casey Schaufler
2019-07-29 21:40 ` Kees Cook
2019-07-26 23:39 ` [PATCH 27/27] AppArmor: Remove the exclusive flag Casey Schaufler
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